TABLE OF CONTENTS

I. Goals of anesthetic management

II. Preoperative preparation of the patient

III. What to expect when you get to the operating room

IV. Pharmacology of anesthesia

V. Airway management

VI. Induction, maintenance and emergence

VII. Regional anesthesia

VIII. Fluid management

IX. Oxygen therapy

X. Subspecialties

a. Obstetrics

b. Pediatrics

c. Cardiac & Thoracic

d. Neuro

e. Critical Care

f. Pain Management

XI. The crashing patient

GOALS OF ANESTHETIC MANAGEMENT

HISTORY

Surgery

Practiced in many forms in all societies for millennia

Limited by pain, bleeding, infection, wiggling patients

Until recently, limited to amputations, repair of lacerations, war wounds

Speed essential, finesse unheard of

Anesthesia

Practiced in rudimentary form wherever there was surgery

Alcohol, herbal concoctions, ―biting the bullet‖, five strong men and a rope main techniques

Hypothermia, shock used on battle fields

Nerve compression for analgesia

Opium used since 17th

century

Mesmerism used in 18th

century

Goal was to keep patient still

Analgesia literally a dream

Modern era

Diethyl ether used for parties – analgesic properties accidentally discovered

1846 Boston - had first public demonstration of the analgesic properties of ether (Figure 1)

Oliver Wendell Holmes coined the name ―anaesthesia‖, against sensation

1847 England – chloroform used in obstetrics, sanctioned by Queen Victoria

1870’s analgesic properties of cocaine put to use as local anesthetic

1880’s spinal anesthesia discovered

Early 20th

century ushered in monitoring of pulse, BP

1940’s stabilization of ether by fluoride to prevent explosions

Modern inhaled anesthetics are fluorinated ethers (Figure 2)

IDEAL ANESTHETIC (See tables 1 and 2)

Analgesia

Amnesia

Sleep

Supports cardiovascular system

Supports pulmonary system

Muscle relaxation

Minimal metabolism

Non toxic

Easy on/off

GOALS

Review full medical history of patient

Relieve anxiety and pain

Review surgical plan

Using above information, create an anesthetized state appropriate for the surgery, safe for the patient

Monitor the patient’s status continually during the procedure

Return patient safely to preanestetized condition

Follow up with pain relief and monitoring as necessary to the status of the patient (post anesthesia

care/ICU, etc)

TRAINING ANESTHESIOLOGISTS

Four years of college

Four years of medical school

Internship year

Three years of training

Fellowship training if desired for subspecialty work

Work as clinician (OR, ICU, Pain management), teacher, researcher

IDEAL

CHARACTERISTICS

INHALED

DRUGS

OPIOIDS SEDATIVES LOCALS INDUCTION

DRUGS

NEUROMUSCULAR

BLOCKERS

AMNESIA

XX XX XX

ANXIOLYSIS

XX XX XX XX

SLEEP XX

XX X XX

ANALGESIA

XX XXX XXX

MUSCLE

RELAXATION

X XXX XXX

SUPPORTS

VENTILATION

XX XX

SUPPORTS

CARDIOVASCULAR

X XX X XX

NON-TOXIC XX XX X XX X

MINIMAL

METABOLISM

XX

EASY ON/OFF XX X X X X

Table 1: Proximity to ideal of anesthetic drugs

THE FIVE ―A‖s - GOALS OF ANESTHETIC MANAGEMENT

Anesthesia – No cognition or awareness of events

Amnesia - No memory of events

Analgesia - No pain during surgery

Akinesis - No movement during surgery

Autonomic stability and physiologic homeostasis

Table 2.

Figure 1: Robert Hinckley painting, 1882, depicting first public demonstration of the use

of ether anesthesia at Massachusetts General Hospital, 1846.

Figure 2: Modern OR and anesthesia

PREOPERATIVE EVALUATION

The key to a successful anesthetic is in the planning. Planning includes

understanding everything about the patient's basic medical conditions,

understanding the surgical plan and possible problems, and understanding the

anesthetic medications at your disposal. As with everything in medicine, it all

starts with the patient. Unless emergency conditions apply, all patients should

be in their best possible condition before undergoing anesthesia and surgery.

Most medical conditions are not improved by the stress imposed by peri-

operative events. The primary care physicians should optimize heart failure,

COPD, etc. ahead of time. But it remains the responsibility of the anesthesia

team to be sure the patient is in optimal condition before an anesthetic is

initiated. What do we do?

HISTORY

Pertinent medical history

Chronic diseases

Medications

Allergies

Social history

Smoking causes irritable airways

Excess alcohol may mean liver disease, induced P450

system

Recreational drugs may cause tolerance/interactions with

anesthetics

Previous surgeries

May impact on present case, eg

Past tracheostomy may mean difficult intubation

Abdominal adhesions may make surgery more difficult

Previous anesthesia

Prepare for known difficult intubation

Past bad reaction can alter plan

REVIEW OF SYSTEMS

Systematic review solidifies history for anesthesiologist

Start from the top and work down

CNS

CVA’s should be documented for residual weakness

Succinylcholine can have fatal consequences in paraplegic

patients

Increased ICP can be worsened by certain medications

Mental status should be assessed

Incompetent patients cannot consent to surgery

Comatose patients are likely to remain that way at end of

case and cannot consent

Pulmonary

COPD – consider baseline evaluation

PFT’s - do bronchodilators help?

Room air ABG

PCO2>50, PO2<60, serious problems post op

Asthma

Emergency room visits/recent exacerbations

Intubations

Triggers

Upper respiratory infections (URI)

Allergies

Smoking

Medications

Sleep apnea

CPAP at home

Baseline O2 Saturation

Cardiovascular

Functional status is key

Activity level

Recent changes

Disease prevalent in diabetes, smokers

History of MI, angina pattern baseline

Need to ensure optimal control preoperatively

Hypertension

Coronary artery disease

Congestive heart failure

Valvular disease

Rhythm disturbances

Hepatic

Liver responsible for metabolism of most drugs

Function compromised by

Alcohol

Hepatitis

Hepatomas

Evidence of dysfunction

Coagulopathy

Ascites

Can quantify with Child-Pugh classification

Renal

Many drugs cleared through kidneys

Creatinine alone poor measure of function.

Compromise leads to

Acid-base disturbances

Electrolyte abnormalities

Volume disturbances

End stage renal failure

Check dialysis schedule

Platelet count

Uremia causes dysfunction

Hemoglobin level

Endocrine

Diabetes most significant

Medications - insulin

Preoperative glucose levels

End organ diseases

Thyroid disorders

Graves disease may show tachycardia and hypertension

Hypothyroidism may lead to slow awakening

Gastrointestinal system

Aspiration risk

Reflux

Bowel obstruction

"Full stomach"

PHYSICAL EXAM

Anesthesiologists usually perform a directed physical exam, focusing on the

cardiopulmonary systems. If regional anesthesia is to be performed, then that

part of the body should be examined for infection, deformities, etc.

Vital signs

Baseline blood pressure (recognizing an isolated measurement

under stress may be misleading), heart rate, respiratory rate

and oxygen saturation

Irregularities should be controlled before surgery

Airway exam (see airway chapter)

Mouth opening

Loose teeth and dentures

Mallampati classification

Neck extension

Cardiac exam

Listen for murmurs, extra sounds

Valvular disease

may have significant implications for management

May require antibiotic prophylaxis to prevent endocarditis

Pulmonary exam - know baseline levels

Wheezes

Rales

Rhonchi

Congestion

LABORATORY EXAMS

Case specific

Patient specific

Premenopausal women need hemoglobin level

ECG for men over 40, women over 50

Chest X-ray for all over 50

ALLERGIES

Medication allergies with reaction should be documented

Relevant food allergies

Eggs - propofol has egg base

Seafood - iodine based disinfectants

MEDICATIONS

All regularly taken medicines should be documented. Certain

medications interact with anesthetic drugs, possibly leading to lethal

results.

Diuretics

Create hypovolemia

See hypotension with onset of anesthesia

Antidepressants

MAO inhibitors interact with meperidine, causing

hyperthermia and possible death

Tricyclics inhibit activity of certain vasoactive drugs

Lithium

Interferes with sodium/potassium channels

Prolongs duration of muscle relaxants

Pain medications

Chronic opioids may create tolerance

Expect to need higher levels

Methadone should be continued

Nonsteroidal anti-inflammatory medications

Cause decreased platelet activity

Should be stopped days ahead of time

Anticoagulants

In general, should be stopped ahead of time as continuation

may lead to excessive bleeding;

Exact management depends on the indication

Chronic atrial fibrillation

Intra-coronary stents

Thromboembolic disease

Consultation with cardiologist, PCP and surgeon to devise

safest management plan currently recommended

Hypoglycemics

Low glucose levels can lead to brain damage

High glucose levels lead to poor healing

Insulin

Should not be taken

Schedule patient early in the day (1st case)

Check morning glucose levels

Start intravenous line early for glucose if necessary

Oral hypoglycemics

Stop several days ahead of time

Steroids

Chronic dosing within past two years leaves patient at risk for

adrenal suppression

Give "stress dose" steroids to maintain stable hemodynamics

100mg hydrocortisone Q 8 hours times three doses

Herbs

Unregulated by the FDA

Can interact with anesthesia drugs

Ephedra causes dysrhythmias

Vitamin E can cause excess bleeding

NPO STATUS

Nausea a common problem with anesthesia and pain medications

Empty stomachs helps decrease risk of aspiration

Solid foods up to six hours preoperatively

Clear fluids up to two hours preoperatively

Water

Sodas

Apple juice

Black coffee or tea

Patients at high risk for aspiration should keep NPO for everything

for six hours

GI reflux

Obesity

Late pregnancy

Diabetes mellitus

Bowel obstruction (probably shouldn’t be eating at all)

ASA CLASSIFICATION (STRATIFICATION OF

RISK)—technically a classification of “health status” was never

meant to be a risk stratification though it has proven to be useful

that way

ASA I - totally healthy patients

35 year old man coming for hernia surgery

ASA II - patients with mild systemic disease under control

35 year old man with hypertension, controlled on one or two

medications, coming for hernia surgery

ASA III - patients with serious systemic disease which impacts

daily functioning

35 year old man with hypertension and insulin dependant

diabetes, coming for hernia surgery

ASA IV - patients with serious systemic disease that is a constant

threat to life

35 year old man with hypertension, insulin dependant diabetes

and in chronic congestive heart failure coming for hernia

surgery

ASA V - patients who are so ill they are not expected to survive

without? the surgery

35 year old man with hypertension, insulin dependant diabetes

and in uncontrollable congestive heart failure needing a heart

transplant

ASA VI - organ donors

E - Emergency situation that needs to be done right away ( full

work-up not possible)

Any of the above examples with strangulated hernia, eg

ANESTHETIC PLAN

Discuss needs of surgery with surgeon ahead of time

Determine best mode of anesthesia for surgery

Local

Regional

General

Plan special techniques as needed

Awake intubations

Regional techniques

Discuss plan with patient

Get patient preferences if possible

Describe plan to them

Describe common risks relevant to patient, case and chosen

anesthetic

Reassure patient with respect to outcome

Give preoperative medications as necessary

Antihypertensive medications

Cardiac medications

Anxiolytics

Pain medication

IV’s

Usually done in hand or arm

Feet may be used if no arm veins available

Patients on chemotherapy

Bilateral mastectomies

External jugular can be used

Very superficial and reliably located

Flow often depends on head position

Central veins (―central lines‖)

Need to be placed with full gown sterile technique

May also be used for central venous pressure

measurements

Special training required

Internal jugular

Subclavian

Femoral

Equipment

IV bags

50mL to1000mL

Choice based on planned usage

Usually use 1000mL bags in OR

IV tubing

Needles/angiocaths

Large bore in cases of anticipated blood and large

volume replacement (18-14 gauge)

Abdominal surgery

Trauma

Small bore for low anticipated volume replacement

(22-18 Gauge)

D&C

Cystoscopy

Alcohol

Tourniquet

Tapes

Gloves

Learning points

Any size IV that works is better than a large bore IV

that doesn’t

The higher the gauge number, the small the catheter

14>22

Cases

1. A patient with asthma is coming to the operating room for inguinal hernia repair.

What are your anesthetic concerns? What are your anesthetic options?

2. A patient with insulin dependant diabetes mellitus is coming to the operating

room for gall bladder surgery. What are you anesthetic concerns? What are the

anesthetic options?

3. A 65 year old man with high blood pressure is coming to the OR for a colon

resection. He is on an ACE inhibitor and a diuretic for blood pressure control.

How might his hypertension affect his anesthetic management? How might the

medication he is on affect his management?

4. A 70 year old man with coronary artery disease is coming for surgery on his

knee. What are your anesthetic concerns? What are the anesthetic options?

WHAT TO EXPECT WHEN YOU GET TO THE OPERATING ROOM

PERSONNEL

Patient

Center of all OR activity

Treat with respect and care even while anesthetized

Nursing

Circulating nurse –

Main link to the ―outside‖

Free to walk in and out of the room at all times

Prepares the room for surgery

Gets supplies

Prepares the patient

Sometimes helps the anesthesia team in its activities

Scrub Nurse –

Is dressed in a sterile manner

Works directly with the surgeons during the operation, handing them instruments, etc.

Knows operations well and anticipates surgeon’s needs

Surgery

Attending surgeon

Admits patient to the hospital

In charge of the case

Is usually the primary operator

Responsible for follow-up of patient care

Is dressed in sterile manner throughout the case

Assistant surgeons –

Depending on hospital will be

Other attending (private hospitals)

Residents (teaching hospitals – trainees)

Help the primary attending with the case and follow up care

Physicians assistant –

Specially trained lay people who assist

During surgical procedures

Postoperative care

Anesthesia

Attending anesthesiologist –

Responsible for anesthetic care of the patient, including

Plan

Execution

Follow up

Will do entire case in private hospitals

Supervises residents and nurses in other hospitals

Residents –

Trainees who are learning the business

Usually do the case in a teaching hospital

Under attending supervision.

Nurse anesthetist –

Specially trained nurses

Administer anesthesia under the supervision of an attending

Team

All above personnel work in concert to take care of the patient during and after the operation

Professional behavior is a must for best outcome

ENVIRONMENT

Temperature

Operating room kept cool

Sterile gowns keep surgical personnel hot

Operating lights keep area very hot as well

Humidity kept low

Keeps personnel and instruments from ―sweating‖

Discourages bacterial growth

Sounds

Music often played to soothe the working environment (tastes vary)

Alarms and beeps from anesthesia monitors

Alarms and beeps from surgical instruments

Talking amongst OR personnel –

Usually about the case

Don’t be surprised to hear discussions on

Current events

Hospital gossip

Bad jokes

Relieves tension in the room.

Extraneous sounds must be kept to a minimum so team can hear each other about patient conditions

Lighting

Varies with the case

Hot direct operating lights are right over the table –

Can be directed for best use

Darkness preferred for laparoscopic surgery

Monitor image is more easily seen

Sterile Areas

Usually covered with blue drape as a warning

These areas should not be touched by unsterile personnel

Anesthesia

Circulating nurse

Visiting students

Maintaining sterility

Cuts down on infections in the patients

Breaking sterility, even accidentally, is a major faux pas

Tension

All surgery is fraught with risk to the patient

Injurious to patient – may be life threatening

Wrong cuts

Wrong medication

Wrong thoughts

OR personnel are people

Respond to this stress differently

Some better than others

Screaming and yelling is never acceptable behavior, though you’ll see it

This usually gets everyone tense

Often used as a stress reliever by the yeller

―Personalities‖ should be left at the door

Good communication is essential

Helps to combat tension

Everyone knows what’s happening

Excess/anticipated bleeding

Unstable vital signs

Missing instruments, etc.

Patient care is best served

MONITORS

Cardiac

ECG –

Monitored continuously throughout a case, no matter how ―minor‖ the case

Nothing is minor to the patients

BP – blood pressure

Is usually monitored with a cuff, via oscillometric method

Measures the oscillations of blood against the vessel walls

Mean arterial pressure is the point of maximum oscillation

Systolic and diastolic pressures are then derived

Usually measured at least every five minutes

Can be measured every minute

ATERIAL LINE PRESSURE –

An invasive way to monitor blood pressure

Directly measuring the flow pressure of blood

Usually in the radial artery

Used when patients are particularly ill, requiring continuous pressures

Anticipated large blood, fluid loss

Used for ABG’s, other lab work

PULSE OXIMETER –

Measures the hemoglobin saturation of blood

Good non-invasive monitor of cardiopulmonary system

Maintain saturation close to 100%

Very alarming when it falls below 90%

CVP – central venous catheter

Measures right heart responses to fluid changes

This usually mirrors the left heart

Good for large volume infusions

Important for pressor infusion (norepinephrine, eg)

PA catheter – pulmonary artery catheter

Used in patients with significant cardiac disease

Monitors left heart pressures through the lungs

Monitors heart’s response to fluid load changes

TEE – transesophageal echo

Used in patients with severe cardiac disease

Gives good information about wall motion and valvular dysfunction

Pulmonary

ETC02 – end tidal C02

Confirms technical placement of endotracheal tubs

Confirms functioning CV system (exchange of 02/C02)

Temperature

Cold room makes patients cold

Don’t coagulate well

Don metabolize drugs well

Monitoring helps ability to keep them warm

Malignant hyperthermia a threat

Disorder of calcium and muscle function

Triggered by inhaled anesthetics

Dramatic temperature rise

Treatment available but must be instituted quickly

PHARMACOLOGY OF ANESTHESIA

The drugs used in anesthesia are many and varied. The following list is not meant to be exhaustive. It is

merely a review of those most commonly used in today’s operating rooms. The reviews concern

metabolism and excretion, mechanisms of action, and how to go about choosing which to use in a given

patient.

IDEAL ANESTHETIC – No one drug satisfies all characteristics of the ideal anesthetic. By combining

drugs the ideal can be approximated.

Analgesia

Amnesia

Sleep

Supports cardiovascular system

Supports pulmonary system

Muscle relaxation

Minimal metabolism

Non toxic

Easy on/off

INHALED DRUGS

It is unknown how and why inhaled anesthetics actually work, though there are many theories. Since they

have so many different effects, it is probable that more than one mechanism is at work. What is known

about them is listed below.

Close to ideal anesthetic

Highly lipid soluble

Cross membrane barriers easily

Potency related to lipid solubility

Rate of onset/offset related to blood/gas solubility

Low blood/gas solubility > enters air (lungs) quickly > fast rate of onset/offset

MAC (Table 1)

Minimum alveolar concentration

1 MAC = dose required to keep 50% of patients still upon incision

MAC is a function of age

Decreases 6% per decade after age 40

Used to compare potencies of inhaled agents

MAC is different for each agent

MACs are additive

0.5 MAC of one agent + 0.5 MAC of another agent = 1MAC for patient

Use less of each to decrease possible depressant effects

CNS

Analgesia

Amnesia

Sleep

Decreased cerebral metabolic rate

Decreased cerebral blood flow

Cardiovascular system

Depressants

Negative inotropes

Use very carefully in patients with significant heart disease

Vasodilators

Pulmonary system

Bronchodilators

Useful in patients with obstructive lung disease

Upper airway irritants

Increased respiratory rate, characterized by rapid, shallow breathing

Decreased alveolar ventilation

Musculoskeletal system

Muscle relaxation

Metabolism

Minimal

Few adverse effects in patients with liver or kidney disease

Non toxic

In/out through lungs

Drugs

Nitrous oxide

Gas

Very low solubility in blood

Favors air filled spaces

Can enlarge air emboli

Can increase pressure of pneumoperitoneum in laparoscopic surgery

Can increase intraocular air in ophthalmic surgery

Rapid uptake and distribution

Low potency (MAC greater than 100%)

Not used alone for total anesthesia

Combined with other agents

Isoflurane

Vapor

Low solubility in blood

Greatest vasodilator of inhaled drugs

Upper airway irritation

Coughing

Salivation

Lower airway bronchodilation

Desflurane

Vapor

Very low solubility in blood

Sympathetic stimulation with onset

Watch for elevations in heart rate and blood pressure with induction

May be dangerous in patients with coronary artery disease

Upper airway irritant

Lower airway bronchodilation

Sevoflurane

Vapor

Low solubility in blood

Mild cardiac depression

No upper airway irritation

Lower airway bronchodilation

OPIOIDS

Opioids work on specific receptor sites in the CNS, the spinal cord and in the periphery. They mimic the

action of endorphins, and decrease neurotransmission of acetylcholine and substance P release at a

presynaptic level. The primary receptors are mu-1, mu-2, kappa and delta, which are responsible for the

clinical effects seen, both desirable and undesirable.

Analgesia

Increase threshold to pain

Modify perception of noxious stimulus

Work best preemptively

No amnesia

Promote sleep

Support cardiovascular system

Vasodilation through histamine release

Depress ventilation

Shift the CO2 response curve and slope

May cause muscle rigidity

Metabolized via liver and kidneys

Non toxic in normal doses

Side effects

Pruritis

Nausea/vomiting

Urinary retention

Constipation

Rate of onset/offset varies with drug

Drugs - agonists (Table 2)

Opioid agonists are used primarily for their analgesic properties, both during anesthesia and post

operatively for pain relief. Choice of drug depends on duration of action needed, available routes and side

effects.

Morphine

Prototype of all opioids

Naturally occurring from opium poppy

Poorly lipid soluble

Slow onset

Long duration

May be given PO, IV, IM, intrathecal

Dose is route dependant

Side effects

Greatest histamine release of all opioids

Stimulates Sphincter of Oddi spasm in cholelithiasis

Meperidine

Synthetic

Structure similar to atropine

May be given PO, IV, IM

Side effects

Myocardial depression in large doses

Build up of metabolite normeperidine (seizures) in renal failure

Tachycardia

Fentanyl

Synthetic

Very lipid soluble

Rapid onset of action

Short duration of action

May be given IV, transmucosal, transdermal, intrathecal

Side effects

Pruritis

Bradycardia

Sufentanyl

Synthetic analogue of fentanyl

Very lipid soluble

May be given IV

Side effects

Severe bradycardia

Skeletal muscle rigidity

Alfentanyl

Synthetic analogue of fentanyl

Very lipid soluble

Fastest onset of opioids

Relatively rapid offset (17 minutes)

May be given by IV, infusion

Remifentanyl

Synthetic

Very lipid soluble

Fast onset

Extremely rapid offset, due to ester hydrolysis (nine minutes)

May be given by IV, infusion

Side effects

No residual analgesia

Rapid development of tolerance

Drugs - antagonists

These drugs are used primarily to counter bad side effects of opioids, such as respiratory depression and

pruritis. Care must be taken when using them, because rapid reversal of overdose and analgesia can lead to

extreme sympathetic response. This can cause tachycardia, hypertension, pulmonary edema and cardiac

arrest.

Naloxone

Reverses opioid effects rapidly

Short duration of action

Repeat doses may be necessary

Continuous infusion helpful

Nalbuphine

Agonist/antagonist

Used primarily to reverse severe pruritis

NEUROMUSCULAR BLOCKERS

This group of drugs interferes with transmission of impulses at the neuromuscular junction (NMJ) by

blocking the function of acetylcholine. There are two groups of drugs. The depolarizing drugs bind with

post synaptic acetylcholine receptors, causing the muscle to depolarize, but prevent rapid repolarization,

resulting in a flaccid paralysis. They cannot be clinically reversed. The non-depolarizing drugs compete

with acetylcholine and bind to post synaptic receptors. Because of this they can be clinically reversed by

increasing the amount of acetylcholine in the NMJ with cholinesterase inhibitors such as neostigmine. They

don’t cause muscle depolarization but keep acetylcholine from doing so, causing muscle paralysis.

Depolarizing Drugs

Succinylcholine only one used clinically

Rapid onset (60 seconds)

Short duration of action (3-5 minutes)

Metabolized by serum cholinesterases

Body metabolizes most drug before it reaches myoneural junction

Active drug is absorbed and taken away by vasculature

Caveats

Some patients have genetic mutation creating abnormal serum cholinesterase

o Can have long duration of action (hours)

Significant release of potassium with depolarization

o Can cause dysrhythmias in patients with

high potassium

conditions which promote production of extrajunctional receptor site

Burns

Renal failure

Prolonged immobility

Can cause significant parasympathetic stimulation

o Bradycardia in children

o Bradycardia with repeat dosing

Myalgias from fasciculations may be caused by depolarization

o Can cause significant patient distress

o Attenuate by giving small dose of non-depolarizing drug prior to giving

succinylcholine

Non-depolarizing drugs

Curare was the first of these drugs discovered. It has a plant source and is the prototype. Curare is

no longer used but many of its laboratory analogs are in use. Choice of drug is based on side effects

and duration of action desired. Quaternary amine structure prevents their passage across the

blood/brain barrier.

Aminosteroids

Pancuronium is oldest

o Causes tachycardia

o Onset of action 3-5 minutes

o Duration 90 minutes

o Primarily cleared through the kidneys

Can have prolonged effect in renal disease

Vecuronium

o No cardiovascular effects

o Onset of action 3-5 minutes

o Duration of action 30-35 minutes

o Both renal and hepatic excretion

Can have prolonged effect in renal disease

Rocuronium

o No cardiovascular effects

o Onset of action 1-2 minutes

o Duration of action 30-35 minutes

o Hepatic and renal clearance

Can have prolonged effect in renal failure

Benzolisoquinoliniums

Atracuronium

o Significant histamine release causing tachycardia and hypotension

o Onset of action 3-5 minutes

o Duration 20-30 minutes

o Metabolized in serum by Hoffman degradation

Good for patients with hepatic or renal failure

Cisatracurium

o Stereoisomer of atracurium

o No histamine release

o Onset of action 3-5 minutes

o Duration 20-30 minutes

o Metabolized in serum by Hoffman degradation

Good for patients with hepatic or renal failure

Mivacurium

o Mild histamine release

o Onset of action 2-3 minutes

o Duration of action 12-20 minutes

o Metabolized by serum cholinesterase

Reversal of non-depolarizing blockers can be achieved with cholinesterase inhibitors. The effect of

acetylcholine at the neuromuscular junction is terminated by cholinesterase. Cholinesterase inhibitors can

increase available acetylcholine to compete with the neuromuscular blockers. This will terminate the effect

of the paralytic drugs.

Monitoring

Monitoring the level of neuromuscular blockade is important for several reasons. For delicate surgery the

patient must remain paralyzed to prevent movement at inopportune moments. However, too deep a

paralysis prolongs the end of the case. When it is time to reverse paralysis depth must be known to judge

amount of reversal to give. Finally, monitoring tells if the patient is reversed enough to maintain

ventilation and protect the airway from aspiration.

Train-of-four

Ideally measure thumb twitch at junction of ulnar nerve and adductor policis longus

Electrodes are placed on ulnar nerve around the wrist

Four impulses are given and twitching of thumb observed (See Figure 1)

o Ratio of first to fourth twitch is noted

o No twitches = full paralysis

o Fading of twitches, 1> 2 > 3 > 4 shows differing depths of paralysis

Ideal is 1 twitch

With reversal, twitching returns with

Four full twitches means at least 50% of muscle fiber receptors are unblocked

Tetany

Tetanic stimulation is more sensitive than train-of-four

o Fade of tetanic contraction after stimulation suggests incomplete reversal

o Maintenance of tetanic contraction suggests 75% of muscle fiber receptors are unblocked

Patient should be able to breathe on their own

INDUCTION DRUGS

When diethyl ether was the only drug available for anesthesia, inhaled inductions were the norm for all

patients. Because ether irritated upper airways, causing coughing, intravenous drugs were developed to

smooth the induction. Now these drugs are used almost exclusively for induction, the addition of inhaled

drugs coming later for maintenance.

Thiopental

o Thiobarbiturate

o Rapid, smooth onset

o Rapid, smooth offset (5-10 minutes)

Due to redistribution from highly vascular tissues to low vascular tissues

Brain is highly vascular, giving appearance of rapid awakening

Over time drug goes back to highly vascular areas, making patient sleepy again

This can occur about 20 minutes later

o CNS depressant

Decreases seizure activity

Decreases ICP

Causes sleep

NOT analgesic

o CV depressant

Decreased inotropy

Vasodilation > hypotension

o Ventilation

Depresses respiratory drive

Decreases minute ventilation

Bronchoconstriction in sensitive patients

o Hepatic metabolism

o Renal excretion

o Given by IV bolus (3-5 mg/kg)

Propofol

o Alkylphenol

o Rapid, smooth onset

Stings smaller veins on infusion

o Rapid, smooth offset (5-10 minutes)

o CNS depressant

May decrease seizure activity

Decreases ICP

Causes amnesia and sleep

NOT analgesic

o CV depressant

Decreased inotropy

Vasodilation, causing hypotension

o Ventilation

Depresses respiratory drive

Decreases minute ventilation

Bronchodilation in most patients

o Hepatic metabolism

o Renal excretion

o Given by IV bolus (1-2 mg/kg)

o Given by IV infusion

Ketamine

o Phencyclidine derivative

o Rapid, smooth onset

o Rapid, smooth offset (5-10 minutes, IV)

o CNS

Dissociated state

May activate seizure foci

Profound amnesia

Profound analgesia

Unpleasant ―dreams‖

Blocked by benzodiazepines

o CV

Strong stimulant of sympathetic system

Tachycardia

Hypertension

Significant negative inotropy when sympathetic activity is tempered

o Ventilation

Supports ventilation

Stimulates secretions

Bronchodilation

o Hepatic metabolism

o Renal excretion

o Given by IV bolus (1-2 mg/kg)

o Given by IM bolus (2-4 mg/kg)

o Also can be given rectally, orally

Etomidate

o Carboxylated imidazole

o Rapid, smooth onset

o Rapid, smooth offset (3-8 minutes)

o CNS

May activate seizure foci

Myoclonic movements common

Amnesia and sleep

Decreased ICP

NOT analgesic

o CV

Mild, if any depression of inotropy

Mild, if any vasodilation

Cardiac ―stability‖

o Ventilation

Mild depression

o Metabolism by ester hydrolysis

o Renal excretion

o Given by IV bolus (0.2-0.3 mg/kg)

SEDATIVE DRUGS

These drugs are used primarily for anxiolysis and sedation.

Midazolam

o Benzodiazepine

o Water soluble (compared to diazepam)

o Rapid onset

o Relatively rapid offset

15-20 minutes,

significantly prolonged in the elderly

o Can be used for induction at high doses (0.1-0.3 mg/kg)

o CNS

Stimulate GABA receptors

Amnesia

Sleep

NOT analgesic

Block seizure activity

o CV

Little effect on inotropy

Some vasodilation, especially in hypovolemia

o Ventilation

Minimal depression

Can cause depression when combined with opioids

o Hepatic metabolism

o Active metabolites excreted via kidneys

o Given by IV bolus (0.02-0.05 mg/kg)

o Given orally (0.5mg/kg for children)

o May be given by IV infusion

o Activity my be reversed with flumazenil (8-15 µg/kg)

Dexmedetomidine

o α2 – agonist

o Rapid onset

o Rapid offset

o CNS

Hypnosis

Sedation

Sleep

o CV

Mild depression

Some vasodilation

Especially with bolus doses

o Ventilation

Mild depression

o Hepatic conjuation

o Renal excretion

o Given as IV infusion for sedation (0.2-0.7 µ/kg/hour)

LOCAL ANESTHETICS

These drugs are used in regional blocks. Their name defines their primary use. They are used to

anesthetize localized areas in the body instead of the entire patient. They are defined by the ester or amide

linkage found between the aromatic head and the hydrocarbon tail that make up the drugs’ structure.

Whether amide or ester, the drugs all have similar properties. They are all weak bases. They cause

analgesia in the area of injection by blockade of nerve conduction. Lipid solubility determines rate of onset

(the higher, the faster), protein binding determines the duration of action (the more bound, the longer) and

they have minimal toxic effects unless injected intravascularly. Then what is manifest is a rapid

deterioration of the patient, starting with CNS activity (tics > peri-oral numbness > tinnitus > seizures >

coma) followed by cardiovascular collapse. Ester drugs may also lead to allergic reactions as par-amino

benzoic acid (PABA), a well known allergen, is a breakdown product. The most commonly used drugs are

listed below.

Esters

Cocaine is the first and the prototype of the local anesthetics. It is a powerful and useful drug, but because

of its high abuse potential it is rarely used clinically.

Procaine

o First useful injectable drug developed in the laboratory

o Rapid onset

o Poor potency

o Primarily used for

Infiltration

Peripheral blocks

Spinal

o Duration 45 min (infiltration)

o Maximum dose 500 mg (infiltration)

Chloroprocaine

o Rapid onset

o Twice as potent as procaine

o Primarily used for

Infiltration

Peripheral blocks

Epidurals

Spinals

o Duration 30-60 minutes

o Maximum dose for infiltration 600 mg

Amides

Lidocaine

o Rapid onset

o Twice as potent as procaine

o Primarily used for

Topical application

Infiltration

Intravenous regional

Peripheral blocks

Epidurals

Spinals

o Duration 60-120 minutes

o Maximum dose for infiltration 300 mg

Mepivacaine

o Rapid onset

o Twice as potent as procaine

o Primarily used for

Infiltration

Peripheral block

Epidural

Spinal

o Duration 90-180 minutes

o Maximum dose for infiltration 300 mg

Bupivacaine

o Slow onset

o Eight times as potent as procaine

o Primarily used for

Infiltration

Peripheral block

Epidural

Spinal

o Duration 240-480 minutes

o Maximum dose for infiltration 150 mg

o High risk of cardiac toxicity if given intravascularly

Ropivacaine

o Slow onset

o Primarily used for

Infiltration

Peripheral nerve block

Epidural

Spinal

o Duration 240-480 minutes

o Maximum dose for infiltration 200 mg

o Similar to bupivacaine, but less risk of cardiac toxicity

If signs of toxicity occur do the following

Stop infiltration

Protect the airway

o Avoid hypoxemia

o Hyperventilate to decrease cerebral blood flow and toxic drug levels in brain

Give midazolam (2-5 mg) or propofol (50mg) or thiopental (50 mg) to prevent or stop seizure

Supportive treatment for CV system

20% lipid emulsions

o Used in cases of local anesthetic cardiac arrest

Usually from bupivacaine or ropivacaine

o Absorbs local anesthetic

o Dosage

Bolus 1-1.5 mL/kg up to 3mL/kg

Maintenance infusion 0.25-0.l5mL/kg/min

EMERGENCY DRUGS

These drugs are kept readily available in the operating room to treat emergency situation, such as

hypotension, hypertension, tachycardia, bradycardia and dysrhythmias.

HYPERTENSION

Hypertension under anesthesia has a variety of etiologies. Problems include:

Bleeding

Myocardial ischemia

CVA

Most common causes include:

Essential hypertension

Light anesthesia

Pain

Hypercarbia

Malignant hyperthermia (extremely rare)

Pheochromocytoma (extremely rare)

Goal is to keep patient normotensive (for them)

Rule out/treat cause. Then use

ß – blockers

o esmolol

ß1-selective

Rapid onset

Rapid offset

Ester hydrolysis

Use small boluses or infusion (0.1-0.3mg/kg/min)

o Labetolol

ß and α blocker

Rapid onset

Slow offset, compared to esmolol

Hepatic metabolism

Use as bolus (5-10 mg at a time)

o Metoprolol

ß1 selective

duration several hours

Give in 5mg boluses

o Propranolol

Nonselective blocker

Long onset/offset

Vasoldilatorse

o Hydralazine

Onset 15 minutes

Can cause profound hypotension form vasodilation

o Nitroprusside

Arterial and veno dilator

Extremely potent

Use with arterial line monitoring of blood pressure

Titrate to effect

o Nitroglycering

Veno dilator

Particularly useful in myocardial ischemia

Titrate to effect

HYPOTENSION

Hypotension has a variety of etiologies. They include

Too deep anesthesia

Lack of stimulation under anesthesia

Hypovolemia

o Diuretics

o Hemorrhage

o Essential hypertension

o NPO

Shock

o Hypovolemic

o Myocardial

o Septic

Rule out/treat cause using

Volume

Blood

Ephedrine

o Indirect α1and direct ß1 stimulation

o Use 5-10 mg IV

Phenylephrine

o Direct α1 stimulator

o Give IV bolus (40-80µg at a time)

o Give IV infusion (titrate to effect)

Epinephrine

o α and ß stimulation

o Very potent

o Used for

cardiac arrest (0.5-1 mg IV)

anaphylaxis (0.01-0.05mg IV or infusion)

Norepinephrine

o Direct α1 stimulation

o Very potent

o Use as IV infusion

Arterial line blood pressure monitoring

Titrate to effect

DYSRHYTHMIAS

Mild dysrhytmias are common under anesthesia, especially in patients with myocardial disease.

Ventricular premature contractions (VPC’s)

o Light anesthesia

o Hypoxia

o Hypercarbia

o Electrolyte abnormalities

Rule out/treat causes, then use

o Lidocaine 50-100mg IV (up to 3mg/kg)

If proceeds to V-Tach use ACLS protocols

Bradycardia

o Baseline slow heart rhythm

o Tugging on peritoneum by surgeons

o Oculo cardiac reflex in eye surgery

o Drug reaction

ß – blocker overdose

Reflex from hypertension

Cushing’s triad from increased ICP

o Sick sinus syndrome

o Malfunctioning pacemaker

Rule out/treat cause, then use

Glycopyrrolate

o Anti cholinergic

o 0.4mg IV

Atropine

o Anticholinergic

o 0.5-1mg IV

Other dysrhythmias should be treated according to ACLS protocols

COMPARISON OF MINIMUM ALVEOLAR CONCENTRATIONS (MAC)

OF COMMONLY USED INHALED DRUGS (VOL %)

ISOFLURANE SEVOFLURANE DESFLURANE

NITROUS OXIDE

1.15 1.85 6.0

104

Table 1.

RELATIVE POTENCIES OF COMMONLY USED OPIOIDS

MEPERIDINE MORPHINE ALFENTANIL FENTANYL REMIFENTANIL

SUFENTANIL

0.1 1 10-25 75-125 250 500-

1000

Table 2.

TRAIN OF FOUR MONITORING FOR NEUROMUSCULAR BLOCKADE

Chart from J. Viby-Mogensen. Clinical assessment of neuromuscular transmission. British Journal of

Anaesthesia 1982;54:209-223. page 209.

Figure 1.

AIRWAY MANAGEMENT

The first tenet of airway management is to remember that ventilation, not intubation, is paramount. If you

can mask ventilate a patient appropriately (read oxygenate) they have a good chance of surviving. If you

can’t mask ventilate, they will die. The second tenet is preparation. That way you are ready for surprises.

Preparation begins with a detailed exam of the airway.

AIRWAY EXAM

Look for

Normal facies

Good mouth opening

Normal teeth

Full view of tonsillar pillars and uvula in open mouth

Predictors of difficult mask ventilation

Facial appearance

o Very small or large

o Large nose

o Beard

o Obesity

Snoring history

Edentulous

Predictors of difficult intubation

Mouth

o Opening less than 3 cm

o Temperomandibular joint (TMJ) dysfunction

Teeth

o Loose teeth can fall out into airway

o Protruding teeth can impede laryngoscopy

o Caps, dentures

Good teeth are hard to injure

Artificial teeth break more easily

Tongue size

o Large can impede intubation

o Mallampati classification can help (see figure 1-3)

Measures tongue size

The larger the tongue, the more difficult the intubation

Hard to get it out of the way

Class I – full view of soft palate, uvula and tonsillar pillars

Class II – partial view of soft palate, uvula and tonsillar pillars

Class III – base of uvula visible

Class IV – soft plate not visible (very large tongue)

Neck

o ―Bull neck‖ (large neck circumference or muscular neck) can make head hard to position

o Large tumors (eg goiters) can make intubation difficult

o Tracheotomy scar –

Indicator of prior airway difficulty and

Concern for potential sequelae of prior tracheotomy, such as tracheal stenosis or

malacia

PREPARATION FOR MANAGEMENT

Equipment (Figures 5-8)

SALT pneumonic

o Suction – make sure it works

o Ambu (resuscitation) bag

o Laryngoscope with different sized blades

o Tubes – several sizes

Appropriately sized masks

Oxygen source

Several sizes of laryngeal mask airways (LMA)

Nasal pharyngeal airways

Oral pharyngeal airways

Sedation

Unconscious patient will not fight you

All others require sedation to minimize the following complications

o Elevations in heart rate, blood pressure

o Ischemic changes on ECG

o Laryngospasm

o Bronchospasm

o Very unhappy, stressed out patient

IV induction (―sedation‖) is best for adults

Small children and uncooperative adults may get oral or IM sedation

MANAGEMENT

Masking (Figure 9)

Choose appropriate size

o Avoid ventilating eyes

Attach resuscitation-bag to oxygen source turned on to 15L/min

Form ―C‖ with thumb and index finger of left hand on mask

Place narrow end over nose and wide end over mouth

Grasp mandible with other three fingers to raise and lift jaw

Squeeze resusci-bag with right hand

Watch for chest rise and ―pinking‖ of patient (again, is assumption here an emergent airway issue

v. elective induction of GA in the OR?)

Problems

o Obstruction of airway

Usually by tongue

Fix with hand repositioning

Place oral or nasal airway as necessary

o Filling stomach with air

Usually seen with children

Reposition mask and hands

Limit positive pressure to less than 20cm H2O

Empty stomach after airway controlled

o Laryngospasm

Vocal cords close and won’t allow air through

Give continuous positive pressure through mask

Deepen the anesthetic with IV or inhalational agent

Small dose of muscle relaxant (succinylcholine) may be needed

o Secretions or stomach contents in mouth

Suction rapidly to minimize aspiration

Securing the airway (Figure 10)

LMA

o Supraglottic device

Sits above the glottic opening

Especially useful in short case (2 hours)

Especially useful when muscle relaxation is not needed- patient breathes on own

o No laryngoscope needed

Blind placement

Slide in along upper palate and down into position

Cuff anchors in position

o Advantages

Easy to learn

No special tools needed

May be less irritating than an ETT as sits above trachea

Pushes redundant tissues out of the way in sleep apnea patients

o Disadvantages

May not ―protect‖ airway from aspiration

Controversial for use in prone position

Air in stomach during long cases and with positive pressure ventilation

Intubation

o Endotracheal placement

Tube sits in trachea 4cm above carina

Positive pressure ventilation can be applied

Can stay in place for up to two weeks

Subglottic stenosis occurs with longer times

Neuromuscular blockers often used to facilitate placement

o Advantages

Offers best ―protection‖ of the airway from aspiration

Can be used for mechanical ventilation

Patients can be given PEEP and CPAP to help improve oxygenation

Medications can be give through tube (pneumonic LANE)

Lidocaine

Atropine

Naloxone

Epinephrine

o Disadvantages

Irritating to airway

Patients must be sedated to keep in place

Can cause bronchospasm in sensitive patients

Requires special equipment for placement

Laryngoscope and blades

Different sized tubes

Requires training

40 successful attempts needed for basic competency

MALLAMPATI ARWAY CLASSIFICATION

Class I Wide mouth opening

Full view of uvula and tonsillar pillars

Class II Wide mouth opening

Partial view of uvula and tonsillar pillars

ClassIII Wide mouth opening

Only base of uvula visible

Class IV Wide mouth opening

No view of uvula or tonsillar pillars

Figure 1

Class I airway

Figure 2

Class II airway

Figure 3.

Class III airway

Figure 4

Class IV airway

Figure 5 –laryngoscope

Figure 6 Oral pharyngeal airways

Figure 7 Placement of oral pharyngeal airway

Figure 8. Placement of nasal pharyngeal airway

Figure 9. Mask ventilation

Figure 10. Endotracheal tube (ETT) and laryngeal mask airway (LMA)

INDUCTION, MAINTENANCE AND EMERGENCE

There are three phases of the anesthetic process: induction, maintenance and emergence. Each is equally

important in terms of risks to the patient and the necessity for vigilance from the anesthesiologist. Each

phase can radically alter the hemodynamic stability of the patient and must be handled with great care.

Ether was the first anesthetic used for controlled anesthesia. It had a very slow time of onset and four

stages of anesthesia were easily identifiable: I was fully awake and conscious. II was the excitation phase,

emerging because inhibitory reflexes were the first to be anesthetized. Patients often flailed about as they

went under. III was surgical anesthesia, with appropriate hemodynamic control of the patient and

unconsciousness. IV was too deep, where hemodynamic control was compromised. The more rapid onset

of currently utilized anesthetics has led to less of a need to characterize depth of anesthesia in this way and

now we divide the anesthetic into the three phases noted above, induction, maintenance and emergence.

INDUCTION

Initiation of the anesthetized state

Loss of consciousness

o Confirmed with loss of eyelid reflex

Apnea occurs

o It is necessary to breath for the patient

Hemodynamic variations occur

o Hypotension from vasodilation and cardiac depression

o Tachycardia in response to hypotension

o Dysrythmias may occur

Drugs used for induction

Anxiolysis

o Helps calm patient for procedure

o Usually benzodiazepines used

Midazolam 1-2 mg

Analgesia

o Helps reduce any pain the patient may have

o Helps to control hemodynamics

Fentanyl 50 micrograms

Lidocaine 1mg/kg

Also depresses airway reflexes

Sleep

o Drug used depends on goals and patient’s basic condition

Propofol for most basic cases

Etomidate for some patients with significant cardiac disease

Ketamine for patients in shock or significant risk of bronchospasm

High doses of opioids for significant cardiac disease

Will sleep for many hours

Muscle relaxation

o Facilitates intubation

Succinylcholine – works in 60 seconds, lasts 3-5 minutes

Rocuronium – works in 60-90 seconds, lasts 30-40 minutes

All others – longer onset and duration

Inhaled drugs

o Can be used for induction

Usually only for pediatric cases without an IV present first

MAINTENANCE

Maintains the anesthetized state achieved by induction

Goal is to maintain a steady state of analgesia, amnesia and muscle relaxation

Close monitoring of blood pressure, heart rate and rhythm, respirations, temperature and urine

output is ongoing

Continues until surgery is concluded

Drugs used

Inhaled gases and vapors

o Nitrous oxide

o Sevoflurane

o Isoflurane

o Desflurane

Choice depends on

o Duration of case

o Properties of drugs

o Co-morbidities of the patient

Intravenous drugs

o Neuromuscular blockers as needed

o Opioids

o Induction drugs for specific properties

Propofol to decrease nausea and vomiting

Vasoactive drugs

o Used to treat hypo/hypertension

Ephedrine

Phenyhlephrine

Labetolol and esmolol

o Used to treat brady/tachycardia

Atropine

Glycopyrrholate

Lidocaine

o Used to treat disrhythmias

Lidocaine

Labetolol and esmolol

Calcium channel blockers

EMERGENCE

Awakening from anesthesia

o Goal is to revert to pre-anesthetic state

All drugs ―turned off‖

o Inhaled drugs blow off through the lungs

o Intravenous drugs are metabolized and excreted – controlled by patient

o Neuromuscular blockers are reversed and return of full muscle strength is verified

o Opioids and benzodiazepines can be reversed but only when necessary

Can cause severe hypertension and tachycardia

Breathing by patient should be resumed

o Must be able to maintain own airway without assistance

Responsive to stimuli, name

Blood pressure, heart rate, cardiac rhythm and temperature should be normal for patient

Endotracheal tube or LMA is removed

Analgesia for the immediate post-operative period should be assured

On occasion it is necessary to keep a patient asleep after a procedure. Emergence is then delayed

into the post-operative period, either in the Post Anesthesia Care Unit (PACU) or ICU.

POST ANESTHESIA CARE

All patients who have received any sort of anesthetic must be observed until they are fully back to baseline.

This will vary with the type of case, patient status and outcome. Once they are stable in the PACU they are

then evaluated for discharge.

PACU Goals

Control pain

Maintain stable hemodynamics

Make sure patient is oxygenating appropriately

Full recovery from anesthetic drugs

Discharge Goals

Outpatients

o Stable hemodynamics

o Pain free

o Nausea free

o Can drink and eat a light snack

o Can ambulate with minimal assistance

Crutches as necessary

o Blocks have worn off

Sympathetic block may last longer than motor or sensory (dizzy on standing up)

Some upper extremity blocks are meant to last long after discharge

Patients must be taught about risks – weak arm

o Leave in the care of family or friend

Inpatients

o Stable hemodynamics

Vitals followed on floor Q 4 hours

o Maintaining airway

Oxygen as necessary

o Pain controlled

PCA

IM/PO medications ordered

o Nausea free

REGIONAL ANESTHESIA

Regional anesthesia is precisely as the name states. Only a specific region of the body is anesthetized with

a local anesthetic.

LOCAL INFILTRATION

Often used by non-anesthesia personnel for small areas

High volume, low concentration of drug is safest

Examples of use include

o Incision and drainage of small areas

o Suturing lacerations

o Dental work

o Inguinal hernia repair

o Plastic surgery in superficial areas

o Preemptive analgesia

Use before all incisions to decrease postoperative incision pain

Drugs commonly used

o Lidocaine 0.5-1% solution

o Bupivicaine 0.25-0.5% solution

o Procaine

Caveats

o Will not work in areas of inflammation

Low tissue pH prevents entry into affected cells

o Danger of toxicity in areas of high vascularity

Volume more important than concentration

Use high volume, low concentration to minimize toxicity

o Beware of using epinephrine to prolong block in end organ areas

May cause ischemia

Finger

Nose

Penis

Toes

MINOR NERVE BLOCK

Blockade of specific peripheral nerve(s) leading to sensory changes limited to distribution of

target nerve(s) only

Does not affect rest of body unless toxic levels achieved

o Common targets include all terminal nerves or nerve plexuses within the extremities

o Upper extremity

Brachial plexus (interscalene , supraclavicular infraclavicular and axillary

approaches)

Achieves motor and sensory blockade of entire upper extremity

o Terminal nerves of the arm (eg radial, ulnar, median at the level of the wrist or elbow, for

more limited upper extremity numbness)

o Digital block (isolated blockade of finger or toe)

o Lower extremity

Femoral Nerve usually approached in the groin

Sciatic nerve – multiple points of approach along the lower extremity beginning

at the gluteus until the popliteal fossa

Combination of femoral and sciatic achieves near complete lower extremity

motor and sensory blockade

Ankle – targets the terminal distributions of the sciatic and femoral nerves at the

level of the ankle.

Adequate coverage of midfoot to toes only

Common drugs used include

o Lidocaine 0.5-2%

o Bupivicaine 0.25-0.5 %

o Mepivicaine 1.5%

o Ropivicaine 0.25-.5%

o 2-chloroprocaine 2-3%

Caveats

o Toxic levels can occur following inadvertent intravascular injections

o Avoid injections into infected areas

o Duration of block depends on amount of drug used

Concentration

Volume

NEURAXIAL BLOCK

Spinal block

o Subarachnoid placement of local anesthetic

o Bathes spinal cord cephalad and caudad from point of entry

o Usually placed in lumbar region

Spinal cord ends around L2 in adults

Higher placement risks injuring the spinal cord with the needle

Produces a dense motor and sensory block

Sympathetic block is two dermatomes higher than >

Sensory block, which is two dermatomes higher than >

Motor block

o Drugs used include

Bupivicaine 0.75%, 1-2cc

Tetracaine

o Only small amount needed

o Block level depends on

Amount of drug used

Baricity of drug used

Hypobaric (mixed with sterile water) will rise to highest level of body

Isobaric will stay close to where injected

Hyperbaric (mixed with glucose) will travel to lowest point of body

Position of patient (see above)

o Duration of block depends on

Amount of drug used

Vasoconstriction in the area

Block is terminated by absorption of drug into vascular system >

metabolism

Blocks can be prolonged by adding vasoconstrictors – epinephrine,

phenylephrine

o Density of block can be deepened by

Opioid co-administration into subarachnoid space

Fentanyl 5-25micrograms

Morphine 0.3-0.5 mg

Also gives some analgesia after block wears off

o Caveats

High sympathetic block (T4-6) can cause significant hypotension

Inhibition of vasoconstriction

Cervical level causes unconsciousness

Inhibition of cardiac accelerator nerves (T1-4)

Decreased cerebral blood flow from hypotension

Can develop hematomas around spinal cord in patients with coagulopathies

Patients may develop postural headaches from CSF leak out of dural hole.

Risk factors for post dural puncture headache:

Young women

Size of needle hole

Prior History of post-dural puncture headache

Treatment:

o Symptomatic with fluids, caffeine

o ―Blood patch‖ may be necessary for severe or prolonged

symptoms

Blood introduced into epidural space which is

hypothesized to clot around dural puncture and seal

the hole

Epidural block

o Placed in potential space outside of the dura

o Bathes nerves as they exit the spinal cord

o Drugs move cephalad and caudad from point of entry

o Catheter may be left in place for intermittent or continuous dosing of drugs

Labor pain control

Postoperative pain control

o Can be placed anywhere along spinal column

Lumbar and low thoracic for abdominal analgesia

High thoracic for chest analgesia

Cervical for neck pain

o Drugs usually used

Bupivicaine 0.125-0.5%

Ropivicaine 0.125-0.5%

Lidocaine 2%

2-chloroprocaine 2-3%

o Addition of opioid intensifies block

Fentanyl

Morphine

Hydromorphone

o Caveats

Large amount of drug must be used for effectiveness

Increased risk of toxicity

Bad headache usually occurs if dura is punctured with epidural needle

Large hole in dura

Cases

1. An 82 year old man is coming to the OR for debridement of a foot ulcer. You elect to place an

ankle block to cover the surgery. His ankle is red and somewhat edematous in places. After

placing the block the surgery starts. The patient begins to scream in pain. Why isn’t the block

working?

2. A 25 year old nervous man is having repair of an inguinal hernia under spinal block. When you

sit him up to place the spinal he becomes bradycardic and hypotensive. What is happening here?

3. You’ve placed a spinal anesthetic into a patient for leg surgery. Ten minutes after placing the

block you notice the patient is hypotensive and tachycardic. What is happening here?

4. After placing a successful epidural into a young woman having labor pains she suddenly begins to

seize. What is happening here?

FLUID MANAGEMENT

Sometimes it seems that what separates medicine from surgery are fluids. Medical

people are always trying to take fluid off patients. Surgical people are always trying to

put it back into patients or at least stop its outflow. During surgery it is the job of the

anesthesia team to manage the fluids. The goal is to maintain the patient as close to

euvolemia as possible. This is done by calculating fluid needs and replacing them

appropriately.

ASSESSMENT OF FLUID STATUS

Proper preoperative assessment of fluid status is critical to minimize intra-operative

problems.

History

Look for sources of occult fluid losses

o Vomiting

o Diarrhea

o Bleeding

o Fevers

Iatrogenic volume contraction

o Diuretics

o NPO

Co-morbidities

o Hypertension

Volume contracted

o Diabetes Mellitus

Glycosuria > polyuria

o Diabetes insipidus

Polyuria

Hypervolemia

o Congestive heart failure

o Pulmonary edema

o Ascites

o Anasarca

o Can be iatrogenic

Vital signs

Weight in kilograms (kg)

Blood pressure findings suggestive of intravascular volume depletion

o SBP <90mmHg

o Decreased pulse pressure (systolic-diastolic)

o Orthostatic changes

BP decreases from supine to standing position

Heart rate rises >10 bpm from supine to standing

ECG

o HR >100bpm

o Dysrythmias and PVC’s

o Weak peripheral pulses

Respirations

o >25 /minute

o May be labored

Urine output

o <0.5cc/kg/hr

o Dark color consistent with concentration

Physical exam

Mental status

o May be anxious

o Comatose if severely hypovolemic

Poor perfusion

o Dizziness may indicate hypovolemia

Mucous membranes

o Dry

o Pale

Skin

o Turgor

Loose

o Color

Pale

Grey

(Pediatrics)

o Sunken fontanelles

o No tears when crying

o Dry diaper for > 8hours

Lab values

High hematocrit

o Falsely elevated from volume contraction

Electrolytes

BUN/creatinine ratio > 20

o Suggests prerenal physiology

Anesthetic/surgical issues that can exacerbate hypovolemia

NPO status of patients

Drugs

o IV induction drugs

All cause vasodilation

o Inhaled drugs

Vasodilation

o Neuromuscular blockers

Histamine release

o Opioids

Histamine release

Techniques

o Neuraxial block (spinals and epidurals)

Sympathetic blockade

Environment

o Cold, dry rooms

o Hot lights

Evaporative losses

Third space loss

o Fluid drawn into interstitial space

Wound edges trauma

Bowel resection

CALCULATING FLUID REQUIREMENTS

Fluids requirements are usually calculated on a 24 hour basis. Since few operations

actually last 24 hours, requirements are calculated on an hourly basis in the operating

room.

Maintenance

Replacement of Fluid lost daily through insensible losses

o Evaporation

o Sweating

o Mucous membranes

4,2,1 rule. Weight in kg*

o 1st 10 kg – 4cc/kg/hr

o 2nd

10 kg – 2 cc/kg/hr

o Rest of weight – 1 cc/kg/hr

Deficit

Maintenance x number of hours NPO

May need to increase because of known problems

o Bleeding

o GI losses

Replacement

Evaporative losses

o From skin of naked patients cleaned with cold disinfectant

o Vasodilation of patient

Blood to periphery

Loss of heat

o Bowel surface exposed to the air

Third space losses

o Traumatized tissue

o Depends on area being traumatized*

Foot – 2cc/kg/hr

Thorax – 5cc/kg/hr

Bowel – 10cc/kg/hr

Blood loss

o Replace only as necessary to optimize oxygen transport.

o Targets controversial. Generally:

Young, otherwise healthy – allow hct in low 20’s

Cardiac disease – maintain hct over 30%

o Watch vitals and lab values for signs of inadequate intravascular volume

and perfusion

Tachycardia

Hypotension

Acidosis (negative base excess)

Ischemia on ECG

Low mixed venous SPO2

o Allowable blood loss can be estimated as follows:

Body weight (kg) x Estimated Blood Volume x (starting Hct –

lowest acceptable Hct/Hct average*

REPLACEMENT FLUIDS

Crystalloids

Hypotonic – used for maintenance

o D5W

o D5-1/2NS

o D5-1/4NS

Isotonic – used for intravascular losses

To replace blood give in a 3:1 ratio, fluid to blood loss

o Normal Saline (NS)

Sodium, chloride

o Lactated Ringers (LR)

Sodium, chloride, calcium, potassium

Be careful in patients with renal failure (potassium)

Avoid using during blood transfusions

Banked blood has calcium citrate which binds to calcium in

fluid

Colloids – maintain oncotic balance in vascular space

Expensive compared with crystalloids

Blood – used when oxygen transport is compromised

o Packed red blood cells (RBC)

Hct about 60%

Use in ratio 2:1 blood to loss

o Albumin

o Blood products – used for coagulopathies

Fresh frozen plasma (FFP)

Platelets

Cryoprecipitate (fibrinogen)

Artificial – may cause bleeding diatheses when used in excess

o Dextran

o Hetastarch

*What is the maintenance requirement for a 78kg man coming to the OR for abdominal

surgery?

1st 10 kg – 4 x 10 = 40cc

2nd

10 kg – 2 x 10 = 20cc

Rest of kg – 1 x 58 = 58cc

118cc/hr

*What is the allowable blood loss for a 65 kg woman who is otherwise healthy and starts

with Hct of 37?

Allowable blood loss = estimated blood volume x (starting Hct – lowest acceptable

Hct/Hct average

[65kg x70ml/kg] x (37- 24/30) =

4550

OXYGENATION: EVALUATION AND TREATMENT MODALITIES

As anesthesia grew as a specialty and surgical cases became more complex, it was discovered that many

patients did not fare well. Research discovered that the single most important factor associated with

anesthesia morbidity and mortality was lack of oxygen. Since that time many safety precautions have been

instituted, with an associated significant drop in morbidity and mortality. How do we evaluate a patient for

hypoxemia?

PATIENT EVALUATION

Systems to be reviewed during acute hypoxemia

Pulmonary

Cardiac

Skin

CNS

Ventilation

Is there breathing?

o If not, breath for them

What is the rate?

o Normal 12-16

Is the breathing labored?

o Use of accessory muscles

Is the rhythm regular? Abnormal rhythms include

o Kusmaul -,deep, slow, gasping and labored associated with severe metabolic acidosis

o Cheyne-Stokes – cycles of tachypnea alternating with apnea associated with deep coma

What is the depth of ventilation?

o Very deep usually associated with slow rate

o Very shallow usually associated with fast rate

Are there ―noises‖

o Stridor

Upper airway partial glottic obstruction

Usually on inspiration

o Wheezing

Lower – small airway partial closure

Usually on expiration

Cardiac

Is there a pulse?

o If not, do CPR with chest compressions

What is the rate?

o Normal 60-100

o Most stressed patients have tachycardia

o Less than 60 may be normal

Athletes

Beta blockade

o Bradycardia after tachycardia during resuscitation is an ominous sign

Heart can last a long time during hypoxemia

Brain lasts 3-5 minutes

What is the rhythm?

o Irregular rhythms may be cause or result of hypoxemia

What is the blood pressure?

o Normal 100-140/60-85

o Most stressed patients are hypertensive

o Hypotension may be the cause or result of hypoxemia

Skin

Color

o ―Pink‖ considered normal

Check mucous membranes in dark skinned people

o Grey, white, blue (cyanosis) are abnormal

o Bright red may be a sign of carbon monoxide poisoning

Temperature

o Warm considered normal

o Cold comes from vasoconstrictive stress response

Moisture

o Dry is normal

o Wet (―clammy‖) comes from sympathetic stress response

CNS

Mental status

o Changes can signify hypoxemia to the brain

Particularly true in the elderly

New agitation or somnolence can be a sign

CONFIRMATION OF HYPOXEMIA

Rapid test

Pulse oximetry

o Measures oxygen saturation of hemoglobin

o Works by the differential absorption of red and infra-red light by oxygenated and

deoxygenated hemoglobin

o Advantages: Quick, reliable and non-invasive

o Disadvantages: Does not work in

Cold patients

Low flow states

Poor perfusion

No pulse situations

Gold standard

Arterial blood gas

o pH, PaCO2 and PaO2 are measured values

o Other values are derived

o Normal

pH 7.4

PaCO2 38-42

PaO2 90-100mHg

o PaCO2

Inversely proportional to respiratory rate or alveolar minute ventilation

< 12, results in higher levels

>16, results in lower levels

o PaO2 affected by FiO2

What should the PO2 be?

PAO2 – PaO2 = A-a gradient

PAO2 = (PB-PH2O) x FiO2 – PaCO2 *

R

*

PAO2 = alveolar partial pressure of O2

PaO2 = arterial partial pressure of O2

PaCO2 = arterial partial pressure of CO2

PB = barometric pressure

PH2O = water vapor pressure

R = respiratory quotient

(For every molecule of O2 consumed there is 0.8 molecule of CO2

produced)

**See examples for calculations

Hemoglobin saturation by oxygen related to but not the same as PAO2

**See figure of oxy-hemoglobin dissociation curve (Figure 1)

Curve affected by

o [H+] or pH

o CO2

o Temperature

o 2,3-dpg

Curve shifts

o To the right with elevations in the above factors

o To the left with decreases in the above factors

True key to adequacy of oxygenation is oxygen content of blood

o Content: CaO2=(Hb x 1.39)%HbSat + PaO2(0.003)

o CvO2=(Hb x 1.39)%HbSat +PvO2(0.003)

o Oxygen consumption = (CaO2 – CvO2) x CO

CaO2 = arterial oxygen content

CvO2 = venous oxygen content

1.39 = oxygen bound to hemoglobin

CO = cardiac output

Five broad causes of hypoxemia

V/Q mismatching

Decreased FRC

Mild pneumonia

Shunting

o Blood going directly from right heart to left heart without oxygenation

Ventricular or atrial septal defects

Pneumonia

Severe atelectasis

Pulmonary edema

Pulmonary embolism

o Differentiate between V/Q and shunting problems by response to supplemental O2

V/Q will correct

Shunting will not correct

Hypoventilation

o Defined as PaCO2 greater than 40mmHg

o Can be caused by

Bradypnea

Parenchymal disease such as COPD

Decreased FiO2

o High altitude

Diffusion problems

Oxygen supplementation

Important therapy or treatment for all hypoxemic states

Amount (FiO2) depends on severity of illness and hemodynamic stability of patient

o Young, healthy patients better able to tolerate short periods of hypoxia than elderly sick

ones

Nasal cannula (Figure 2)

o Well tolerated

o Creates reservoir of 100% O2 in nasopharynx

o Room air then entrained around nasal prongs

o At a maximum of approximately 6 l/min capable of producing FiO2 of 35%

Simple face mask (Figure 3)

o Covers nose and mouth

o Larger reservoir so less room air entrained > higher FiO2 than nasal cannula

Face mask with reservoir bag (Figure 4)

o Highest FiO2 of all adjuncts for oxygenation

o Reservoir has valve which prevents CO2 from entering bag, maintaining high O2 content

Caveats

o Adjuncts must be placed on patient appropriately

Not on cheeks, chin or forehead

o Adjuncts must be appropriately connected to an oxygen source which is turned on and

not empty

Oxygen tanks

Sized A-H

Sizes D and E are most commonly used for hospital transport (Figure 5)

All oxygen tanks are filled to a pressure of 2000 pounds per square inch (psi)

There is a direct relationship between the pressure in the tank and the volume in the tank

o 2000 psi = full

o 1000 psi = ½ full

o 500 psi = ¼ full

A full D tank of oxygen holds 400L

A full E tank of oxygen holds 650L

Safety considerations

o Oxygen tanks are generally made of iron and therefore magnetic

DO NOT take them into an MRI suite

Special aluminum tanks are available for this

o Tanks are heavy and unstable

Always carry in special cradle or lie it down

Falling tanks are injurious

Falling tanks can explode

Question:

An E oxygen tank is reading 1000psi. How long will the oxygen last if the flow rate is

10L per minute?

A D oxygen tank is reading 2000psi. How long will the oxygen last if the flow is 4L per

minute?

Figure 1: Oxyhemoglobin dissociation curve

Figure 2a: Nasal cannula

Figure 2b: Nasal cannula in place

Figure 3a: Simple face mask

Figure 3b: Simple face mask in place

Figure 4a: Non-rebreather mask

Figure 4b: Non-rebreather mask in place

SUBSPECIALTIES

There are several subspecialty fields in anesthesia. All anesthesiologists are trained to perform in these

areas, but it is possible to spend extra fellowship time in them for bench or clinical research, as well as

advanced clinical training. At the present time cardiac, pain and intensive care (ICU) have separate,

additional board certification

OBSTETRICS

Labor and delivery

European anesthetics started here

o Goal was to relieve pain of labor and delivery

o Chloroform was drug of choice

o Women were anesthetized

Cognitive and physical participation in delivery was impaired

Pushing through stage 2 of labor was compromised with full anesthesia

Partial (―twilight sleep‖) enabled woman to push

Neonate was anesthetized as well

Modern general anesthesia

o Used for Cesarean section

Usually for ―stat‖ situations

Also when regional is contraindicated

coagulopathy

o Mother asleep

o Mother at risk for aspiration during induction

―full stomach‖

Difficult airway

o Sedation of neonate

All inhaled and IV drugs cross placenta

Regional anesthesia

o Epidurals allow an awake mother

o Pain control could last for many hours

o Little to no anesthesia of neonate

Small amounts used in mother

Very small amounts get to fetus

o Epidural level can be raised for Cesarean sections

o Spinals usually used for Cesarean sections

Profound analgesia

Awake mother

No sedation of neonate

High risk pregnancies

Early involvement of anesthesia team – days to weeks prior to delivery – can significantly reduce morbidity

and mortality of mother and child

Pre-eclampsia

o Monitoring of mother’s vital signs

Arterial lines

CVP lines

o Control of blood pressure via

IV drugs

Epidurals

Eclampsia

o Help control seizures

o Monitor mother and child vital signs

o Anesthesia for Cesarean sections

Usually cures the problem

Cardiac abnormalities of mother

o Often unmasked by pregnancy

o Mitral stenosis

o Aortic stenosis

o Congenital defects

o Transplanted hearts

Pulmonary abnormalities of mother

o Pulmonary hypertension

o Severe asthma

o Cystic fibrosis

Renal disease in mother

o Blood pressure control

o Dialysis issues

Remember, in obstetrics two patients are involved. Care of the mother usually improves the outcome of the

fetus.

PEDIATRICS

Children are not just small adults. Aside from the obvious differences in size, there are physiologic

differences between children and adults which are most pronounced before age eight. Extra training is

most important for the less common, more serious problems, such as congenital issues and transplantations

Neonates

o Cardio-pulmonary physiology radically changes in first minutes of life

In utero vs. at the time of birth and for the next few weeks

Intra cardiac shunts persist for several weeks

Lungs are not fully developed

o Head is large compared to rest of body

Soft fontanels don’t protect the brain well

Positioning problems

Airway issues

Short airway

Small airways

Increased airway resistance

o Especially with edema or inflammation

o Hepatic and renal function is immature

Drug metabolism differs

Fluid balance must be carefully controlled

o Hemoglobin F is prominent

Oxygenation may be compromised

Gradually reduces over three months

Relative anemia at that time

o Poor temperature control mechanisms

Cannot shiver

Healthy babies have some capacity for non-shivering thermogenesis

Body surface area is large compared to size

Must keep externally warm

o Congenital abnormalities may be present

Meningomylocele

Gastroschisis

Tracheo-esophageal fistulas

Diaphragmatic hernia

Many more

Infancy – 0-12 months

o Normal children continue to grow – may require

Hernia repair

Orchiopexy

Orthopedic problems

o Congenital abnormalities require repair

Tetralogy of Fallot

Pulmonary atresia

Transposition of great vessels

Hypoplastic left heart syndrome

Duodenal atresia

Anal atresia

Some abnormalities may appear late

1 year >

o Abnormalities may appear late

Myopathies

o ENT issues

Hypertrophied tonsils and adenoids

Ear infections

Chronic URI

o Orthopedics

Bone fractures

Congenital abnormalities

o General

Appendicitis

Hernias

Transplantation

o Common in large centers

Kidney

Liver

Heart

Abdominal organs

CARDIAC & THORACIC

Cardiac surgery has become quite common and successful. This is due to significant advances in surgical

techniques and to highly sophisticated methods of anesthesia induction, monitoring and maintenance.

Extra training enhances the outcome of the particularly difficult cases.

Patients

o Often quite ill

Cardiac problems

Coronary artery disease

Valvular problems

Cardiomyopathies

Conduction and rhythm abnormalities

Major aortic disease

o Aneurysm

o Dissection

Cardiac tumors

Pericardial disease and tamponade

Cardiac trauma

Pulmonary embolisms

Congenital abnormalities

Pulmonary problems

Pulmonary hypertension

Tumor surgery

Congenital abnormalities

Lung disease requiring transplant

Thoracic sympathectomy

Lung volume reduction surgery

Lung trauma

Multi-organ failure as a result of the above

Often elderly

Anesthesia

o Advanced methods of induction and maintenance of anesthesia

o Monitoring includes

Arterial lines

Pulmonary artery catheters

Intra operative echocardiography

Cardio-pulmonary bypass

Adult extracorporeal membrane oxygenation

Cerebral oximetry

o Emergence may be over hours or days (in ICU)

o May use thoracic epidurals for post op pain control

o Close communication with surgical team

o Lung isolation techniques

Univent tubes

Double lumen tubes

Bronchial blockers

Jet ventilation

Procedures

o Coronary artery bypass (CABG)

o Valve repair/replacement

o Percutaneous valve replacements

o Arrhythmia ablation

o Transplantation

Hearts

Lungs

Both

o Implantation of assist devices, pacemakers

o Pneumonectomy

o Esophagectomy

o Lobectomy

o Rib resection

o Reflux surgery

NEURO

Neuro surgery remains very delicate and time consuming. The brain is probably the least forgiving of

organs with respect to trauma and oxygen deprivation.

Patients

o Can often be healthy except for neuro disease

Brain compartment is isolated from rest of body

Communication may be compromised due to mental status

o Tumors

o Aneurysms

o A-V malformations

o Strokes

Anesthesia

o Maintain cerebral oxygenation, blood flow (CBF) and perfusion (CPP)

o Decrease cerebral metabolic rate (CMVO2)

Decreases ischemia in compromised tissue

o CPP = MAP–ICP

ICP = closed compartment pressure

Affected by

Tissue mass

Blood volume

Cerebral spinal fluid (CSF)

Control by decreasing

Tissue mass – diuresis

Blood volume – hyperventilation

o ↓CO2 > cerebral vasoconstriction

CSF – spinal drain

o Careful induction and maintenance to maintain CPP

Most anesthetics ↓ CMVO2

o Hemodynamics may be altered by patient status/surgical manipulation

Cushings’s Syndrome – ↑ ICP >

Hypertension

Bradycardia

Brain herniation – from ↑ ICP

Hemorrhage

↓ BP

o Careful emergence

Need awake patient immediately to evaluate mental status

o Close communication with surgical team

Procedures

o Tumor resection

o A-V malformation repair

o Aneurysm clipping

o Brain mapping for seizure control

o Trauma repair

Hematomas

CRITICAL CARE

Historically, ICU’s were conceived and put together by anesthesiologists who were trying to optimize care

of patients requiring mechanical ventilation. This has evolved into a complex specialty caring for critically

ill patients after general, neuro and cardiac surgery, as well as non-surgical patients from medicine,

coronary and neurology units and pediatric patients. Presently intensivists from anesthesia are primarily

involved in the care of post-surgery patients in all the specialty areas.

Patients

o All types of surgery

o Single organ issues (neuro, eg)

o Multi-organ failure

Trauma

Critically ill prior to surgery

Dramatic events during surgery

Postoperative complications

o Presumption of survival

Anesthesia - intensivist

o Coordinates all care

Medications and support

Hemodynamic monitoring

Ventilation parameters

Necessary procedures, eg

PA lines

CVP lines

Thoracentesis

Pericardiocentesis

Paracentesis

Surface ultrasonography

Transesophageal echocardiography

Bronchoscopy

o Confers with surgeons about disposition

Possible returns to the OR

Post ICU care

o Confers with patients, family about prognosis

Includes Do Not Resuscitate orders

Futility assessment

Post ICU care

Studies support the fact that patients have better outcomes when intensivists coordinate care.

PAIN MANAGEMENT

Pain management is a natural outcropping of anesthesia care. Anesthesiologists manage pain issues

intraoperatively and in the Post Anesthesia Care Unit (PACU). Over the years this has expanded to

consulting and managing pain issues in post op patients, non surgical patients and chronic, out-of-hospital

pain.

Why manage pain?

Major discomfort for patient

o Anxiety

o Stress

Leads to physiologic derangements

o CV

Hypertension

Tachycardia

Myocardial ischemia

Dysrhythmias

o Pulmonary

Hyperventilation

Hypocapnea

Atelectasis

Hypoxemia

o Stress response trigger

Coagulation cascade

Blood clots

o Post Traumatic Stress Disorder (PTSD)

Mechanism of pain

o Tissue damage activates nociception

o Peripheral nociceptors send signals to dorsal horn of spinal cord

o Spinal cord afferents send signals to contralateral thalamus

o Signals then go to sensory cortex and other areas of the brain

Interruption of pain pathways

o Anti-inflammatory drugs block peripheral nociceptors

o Spinals and epidurals block spinal cord responses

o Opioids block central and peripheral pain responses

Post operative pain

o Acute, usually short lived pain – symptom of injury

Outpatients

Should be tolerating pain prior to discharge

IV medications need converting to oral

Short acting opioids and nonsteroidal and anti-inflammatory drugs are

mainstays

o Fentanyl 25-50 µg IV

o Vicodin®

o Percocet®

o Tylenol®

o ketorolac®

Nerve blocks with local anesthetics

o Most useful for upper extremity surgery

o Allows for prolonged pain relief

Warn patients about lack of sensation and motor

block

Inpatients

Can titrate longer acting opioids

IM, IV, intrathecal routes

Patient Controlled Analgesia (PCA)

o Patient self-medicates via IV or epidural catheter

o Steady state infusion can also be given

o Removes anxiety and stress from patient waiting for

medication

o Ultimately use less drug

Intrathecal opioids

o Placed intraoperatively

o Can last for many hours

Continuous epidurals

o Allows early ambulation

o Allows for physical therapy after orthopedic procedures

Peripheral nerve blocks

o All extremities can be blocked

o Pleural and intercostals blocks

Good for fractured ribs

Good for chest tubes

Chronic pain

o A disease in itself

o Usually from previous trauma that never gets controlled

o Emotional and functional disability involved

o Requires treatment of functional, emotional, behavioral and cognitive issues

o Most common syndromes include

Low back pain

Headache

Cancer pain

Neuropathic pain

Abdominal pain

o Treatments is multimodal

Consultations with

Neurology

Phychiatry

Surgery

Pain medications

Nerve blocks

Anti depressant drugs

Counseling

Physical therapy

o End stage cancer pain requires adequate palliation

o Goal is to get patients back as close to original functional status as possible

THE CRASHING PATIENT

The crashing patient requires immediate attention. Regardless of the cause certain steps must be taken to

support the patient while the underlying problem is identified and treated. The initial steps are the simple

ones that many people forget in the heat of the moment. The algorithms below will help you stay

organized and focused until you can sort out the cause of the problem. Good team work also improves

patient survival and outcome.

Assess ABC’s

Airway

o Make sure it is patent

o May be obstructed by

Tongue

Trauma

Edema

Blood

Foreign body

Breathing

o Is the patient breathing?

o Is the patient breathing adequately?

Normal rate is12-16/minute

<12 may be due to

o drug effect

o CNS depression

>16

o Sympathetic activation

o Anxiety

o Pain

o Hypoxia

o Hypercarbia

o Acidosis

o Sounds

Wheezing

Expiratory phase

Lower airway partial obstruction

Stridor

Inspiratory phase

Upper airway partial obstruction

Circulation

o Check pulse in several locations

Carotid, femoral best

Radial may not be palpable

Vasoconstriction

o Heart rate

Normal 60-100

<60

Beta blockers

Athlete with high vagal tone

Ischemia

Cardiac failure

Conduction abnormalities

>100

Sympathetic stimulation

Anxiety

Pain

Hypovolemia

Fever/sepsis

o Nature of pulse

Weak, thready

Hypovolvemia?

Bounding

Sepsis?

Irregular

Dysrhythmias

o Blood pressure

Normal 100-140/60-85

<100

Normal?

Hypovolemia

Heart failure

Peripheral vasodilation

o Sepsis

o Anaphylaxis

>140

Sympathetic stimulation

Anxiety

Pain

Hypervolemia

Secure airway if at risk

Intubate if necessary

o Poor or no gag reflex

o PaO2 < 60 mmHg on 100% O2

o PaCO2 > 50 mmHg

Administer supplemental oxygen (generally 100%)

Requires non-rebreather face mask.

o Simple face mask and nasal cannula inadequate

Low perfusion states benefit from supplemental O2

o Increases O2 content of blood

Always give 100% except in three special situations

o COPD with CO2 retention

May be dependant on hypoxic drive to breathe

o Neonates

High O2 may cause blindness

o Bleomycin chemotherapy

Causes pulmonary fibrosis

High O2 accelerates this

Start IV’s

For administration of fluids and medications

Antecubital is easiest and best

o Away from chest in case compressions are necessary

In Chest trauma

o Avoid neck and chest lines

o May have ruptured vessels there

In Abdominal trauma

o Avoid femoral lines

o May have ruptured vessels there

18 gauge minimum

o Flow is inversely proportional to catheter diameter.

o 18G and smaller considered ―large bore‖ catheters and thus capable of rapid fluid

administration

12>14>16>18

Resuscitative fluid options

Crystalloids have a half-life of several hours in the intravascular space

o Lactated Ringers (LR)

Isotonic

Contains sodium, chloride, calcium and small amount of potassium

Avoid in hyperkalemia

Avoid with blood products

o Calcium binds with preservative

Can lead to metabolic acidosis

o Normal Saline (0.9%)

Isotonic

Contains sodium and chloride

Can lead to hyperchloremia and metabolic acidosis

Good for infusing with blood products

o Plasmalyte

Isotonic

Contains sodium, potassium, chloride and magnesium

Avoid in hyperkalemia

Good for infusing with blood products

o Glucose

Hypotonic

Causes

Hyperosmolality

Osmotic diuresis

Cerebral ischemia

Acidosis

Avoid unless patient has hypoglycemia

Colloids

o Have large molecules which keep fluids intravascular

Increase oncotic pressure

o May be preferred over crystalloids if intravascular volume depletion is primary problem

o Examples include:

Blood and blood products

Albumin

Half-life is 16 hours in plasma

Hydroxyethyl starch

Half-life is 17 days

Dextran

Half-life several days

Attach monitors

ECG

o Monitors heart rhythm, and rate

Pulse oximeter

o Pulse

o Hemoglobin saturation by oxygen

o May not work in very low flow states

Automated blood pressure

o Frees up hands

o Machines set at pulse of 40

May not work in severe bradycardia

Assess vital signs at least every five minutes

o Every intervention may cause change

Review history

Family members, prior caregivers, chart

85% of diagnosis comes from history

Most likely cause of problem is probably the right one

Perform focused physical examination

Next 10% of diagnosis comes from physical exam

Focus on most like causes first

o Admitting dx rule out MI?

Check for MI

o Admitting dx GI bleed?

Check for bleeding

o Admitting dx gunshot wound?

Looks for wounds all over

Order 12-lead ECG

Gives view of the heart from 12 different angles

More accurate than monitor

Hard copy for study

Order portable chest X-ray

Rules in/out pulmonary pathology

Checks placement of endotracheal tube, chest tube, access lines, etc.

Order labs

ABG for pH, PCO2, PO2,

CBC for hemoglobin and plateletes

Metabolic panel for electrolytes

Others based on history

What is the nature of the problem?

Blood pressure determined by vascular tone (SVR) and cardiac output. As such, alterations in blood

pressure fall into one of 3 categories:

Rate problems

Volume problems

Pump problems (heart)

Rate

Too fast—

o Impair venous filling and stroke volume suffers

Diastolic time shortened

Heart fills during diastole

o Sinus tachycardia

o Atrial flutter

o Paroxysmal supraventricular tachycardia (PSVT)

o Ventricular tachycardia

Too slow

o Sinus bradycardia

o Type I and II second degree AV block

o Third degree heart block

o Pacemaker failures

Treat according to American Heart Association protocols

Volume problems

Volume loss

o Hemorrhage

o GI loss

Diarrhea

Vomiting

o Renal losses

o Insensible loss

Fevers

o Adrenal insufficiency

Aldosterone

Vascular resistance

o Third space loss

o Sepsis

o Drugs that alter tone

Spinal anesthesia

o Central nervous system injury

o Spinal cord injury

o Adrenal insufficiency (cortisol)

Evaluating volume loss

o See chart 1

Evaluating response

o See chart 2

Vasopressors

o Used to help maintain BP until adequate fluid resuscitation has occurred

Ephedrine (bolus 5-10 mg Q five minutes)

Phenylephrine (bolus or infusion)

Epinephrine (infusion)

Norepinephrine (infusion)

Vasopressin (infusion)

Pump problems

Primary

o MI/ischemia

o Myocarditis

o Ruptured chordae

o Acute papillary muscle dysfunction

o Acute aortic insufficiency

o Prosthetic valve dysfunction

o Ruptured intraventricular septum

Secondary

o Drugs that alter function (beta blocker overdose)

o Cardiac tamponade

o Pulmonary embolus (PE)

o Atrial myxomata

o Superior vena cava syndrome (SVC)

o Pulmonary edema

How to treat?

o Assess blood pressure

Systolic BP < 70 with signs and symptoms of shock (chest pain, altered

consciousness, cold, clammy extremities)

Norepinephrine 0.5-20 µg/min

Dopamine 5-20 µg/kg/min

Systolic BP 70-100 with signs and symptoms of shock

Dopamine 2.5-20 µg/kg/min

Add norepinephrine if dopamine is >20 µg/kg/min

Systolic BP 70-100 with no signs or symptoms of shock

Dobutamine 2-20 µg /kg/min

o Primary problems

Cath lab>thrombolytics>cardiac surgery as needed

o Secondary problems

Supportive therapy

Pericardiocentesis for tamponade

Thrombolytics for PE

Surgery to remove myxoma

Radiation for lung tumors causing SVC syndrome

Pulmonary edema

Furosemide

o Increase venous capacitance for fluid

o Diuresis of excess fluid

Nitroglycerine

o Increase venous capacitance for fluid

o Dilates coronary arteries in ischemia

Morphine sulfate

o Increase venous capacitance

o Analgesia

o Anxiolysis

EVALUATING VOLUME LOSS

Class I Class II Class III Class IV

Blood Loss (ml) Up to 750 750-1500 1500-2000 >2000

Blood Loss

(%BV)

Up to 15% 15-30 % 30-40% >40%

Pulse Rate <100 >100 >120 >140

Blood Pres Normal Normal Decreased Decreased

Pulse Pres Normal or ↑ Decreased Decreased Decreased

Resp Rate 14-20 20-30 30-40 >35

Urine ml/hr >30 20-30 5-15 negligible

Mental status Slightly anxious Mildly anxious Anxious and

confused

Confused/

lethargic

Fluid(3:1) Crystalloid Crystalloid Crystalloid/

blood

Crystalloid/

blood

Chart 1. Look at vital signs and mental status to estimate volume loss. Based on results, appropriate

volume resuscitation can be instituted.

EVALUATING PATIENT RESPONSE

TO VOLUME TREATMENT

Rapid Response Transient Response No Response

Vital Signs Return to normal Transient

improvement

Remain abnormal

Est. Blood Loss Minimal (10-20%) Moderate/ ongoing

(20-40%)

Severe (>40%)

Need for more

Crystalloid

Low High High

Need for Blood Low Moderate/high Immediate

Blood Prep Type and cross Type-specific Emergency blood

release

Operative

Intervention

Possibly Likely Highly likely

Surgical Consult Yes Yes Yes

Chart 2. Use isotonic solutions such as Ringer’s Lactate or Normal Solution for resuscitation. Use blood

as necessary.