Anesthesia Pharmacology

Clinical Pharmacology of Anesthetic drugs

Dr. Waddah H. Awad

PSHM – Anesthesiologist

pshm.edu@hotmail.com

General Anesthesia

• Definition – Induced, Reversible, controlled, loss of sensation

• Components:

1. Analgesia

2. Muscle relaxation

3. Amnesia

4. Suppression of excessive autonomic

responses

Practical Conduct :

• Pre Anesthetic check up• Just preoperative monitoring • Induction • Maintenance• Recovery• Post operative Care

Monitoring

Maintenance

Induction Recovery

Pre op. Check Post op. Care

Anesthesiologist Tools

Drugs : Hypnotics, Analgesics, Muscle

relaxants & others

Gases : Oxygen, Nitrous Oxide

Vapors: Halothane, Isoflurane, Sevoflurane

Equipments : Anesthetic Machine - Breathing

Circuits, Monitors…….

Others: iv access, Infusion fluid, Airway

equipments……..,…..

Premedication

Reasons for administration of pre-medications

1. Reduction of fear and anxiety

2. Reduction of saliva secretion

3. Prevention of vagal reflexes (caused by surgical stimulation like squint op., stretching of anal sphincter, or associated with medication e.g. β-blockers

4. As part of anesthetic technique e.g. use of narcotics

5. To produce amnesia

- Hyoscine ( Scopolamine)

- Benzodiazepines - anterograde amnesia

- Diazepam -hyoscine – in 75% pts complete amnesia

6. For specific therapeutic effects

- Transdermal glyceryl nitrate patches for angina pts,

- Steroids

- βblockers

Premedication

Drugs :

1. Anxiolysis\ Amnesia: BNZ, Hyosc., Antihist. (H1 Blochers) 2. Analgesia: Opiates

3. Adjuvant to GA : BNZ & Ketamine

4. Anti-emetic : Metoclopramide, Antihist.

5. Antacids : H2 blockers, Antihist., Na Citrate

6. Antihist. : Promethazine,Diphinhydramine

7. Antivagal / Antisialagogues: Atrop, Hyos.,AntiH

8. Antitromb. / Anticoag.: Heparin, Stockings

9. Antibiotics: Infective Endocarditis Prophylaxis

10: Attention to pre-existing medications:

Continue: unless otherwise

Stop : MAOI, Contraceptive pills

Change : Insulin, oral hypogly., Steroids

Drugs :

Common Premadications

Drug Dose Route TimingDiazepam 5-15 mg oral 1-2 hrLorazepam 1-3 mg oral preop.

Morphine 5-15 mg IM Hyoscine 0.2-0.4 mg IM 1hr pre

Pathedine 50-100mg IM preopPromethazine 12.5-25mg IM Midazolam 2.5-5 mg IM

Children

Drug Dose Route Timing

Diazepam Syrup 0.2mg\kg oral 1 hr Medazolam 70-100 mcg\kg IM preop

Promethazine2-5yr 10-20mg oral 1hr preop5-10 yr 20-25 mg 1\2dose for IM Morphine 0.1-0.2mg\kg IMHyoscine 5mcg\kg IM

Side effect of premadications :

Delayed recovery and interaction of Specific drugs

Opioids

Act on opioid receptors located through out CNS

• Identified as mu - mu1 & mu2

keppa (k)

delta (d)

sigma • Most effective as producing analgesia• They provide some degree of sedation

IV opiates

Drugs Dose Onset Duration

Morphine 0.1-0.2mg\kg slowest long

Pathedine 1-2 mg\kg slow long

Fentanyl 1-2mcg\kg rapid short

Alfentanil 10-20mcg\kg v. rapid v. short

Sufentanil 0.2-0.4mcg\kg rapid short

Induction

Check: pt \ machine\ Monitors

Monitoring:

Basic Monitoring:

Anesthetics, clinical, Airway, EKG,NIBP,SpO2, Capenography

Add.: PNS\Temp.\ CVP

Agent for induction : IV vs. Inhalational

Analgesia: Opiates

IV Induction Agents

• The ideal intrav. Agent reliably and pleasantly induces full anesthesia within one arm-brain circulation time

- is free of side effects

- completely wears off in a few minutes

- it must be capable of infusion to maintain

anesthesia without problems.

I.V. anesthetic agents may be used for

1. Induction of anesthesia

2. As a sole agent for operation (TIVA)

3. To supplement volatile anesthesia or regional anesthesia

4. For sedation

IV Induction Agents

Propofol – - Mechanism of action – facilitation of inhibitory

neurotransmission mediate by GABA - Not water soluble- 1% solution aqueous solution is available for IV

use as an oil-in-water emulsion containing - soybean oil - egg lecithin - glycerol

• Only for IV administration

• Rapid on set ( one arm brain circulation time)- 1\2 life 2-8 min. ( recovery rapid, no hangover)- high clearance rate( 10 time that of thiopentone)

• Conjugation in liver results in inactive metabolites

• Excretion – in urine

• Can be used in Chr. Renal F, hepatic ds.

Thiopent. Propofol Ketamine barbiturate phenol phencyclidine

Pain - - + - -

Phleb. Less more less

Rapid onset ++ +++ +

BP decrease decrease increase

Analgesia -- -- +

Bronch ppt Asthma -- +

Mech. of act. GABA GABA Desociat.

Recovery Hang over clean headed Emerg. Delir.

PONV + - Antiemetic + antipruritic

Duration 10 min 10 min < 10min

Route iv i.v i.v \ i.m

Life Support During Induction

A. Airway : Support: manual \ Atrif. Airway

B. O2 FM + circuit +- An. Agent

Chest expansion\ bag \ monitor

C. Circulatory Support

D. Definitive Airway : Guedel`s Airway

Laryngeal Mask Airway

ETT MR + Circuit + IPPV

MAINTENANCE

Anesthesia ( Tetrad) :

Unconsciousness : Inhal. Vs TIVA

Analgesia : N2O + Opioids / LA

Relaxation : M.R.

Autonomic : Pares. : Anticholin.

: Symp. : GA

Opioids

CVS drugs

Inhalational Anesthetics

• The greater the uptake of anesthetic agent, the greater the difference b\w the inspired and alveolar conc. And slower the rate of induction.

• Three factors affect anesthetic uptake

1. Solubility in the blood

2. Alveolar blood flow

3. partial pressure difference b\w alveolar gas

and venous blood.

• The relative solubility's of an anesthetic in air, blood, and tissues are expressed as Partition Coefficients

Partition Coefficients• N2O 0.47 ( insoluble in blood)

• Halothane 2.4• Isoflurane 1.4• Desflurane 0.42• Sevoflurane 0.65 (Factors that speed induction also speed recovery)

• MAC – the alveolar conc. of an inhalational anesthetic

that prevents movement in 50% in response to

surgical stimulus.

- a measure of potency

Agent MAC%

Nitrous oxide 105

Halothane 0.75

Isoflurane 1.2 Sevoflurane 2.0

Desflurane 6.0

Inhalation Agents

• ISOFURANE – dilates coronary arteries ( but less potent than nitroglycerine or adenosine).

- Can cause (coronary steal syndrome) regional myocardial ischemia)

• DESFLURANE – Low solubility of desflurane in blood and tissues causes a very rapid wash in and wash out of anesthetic.

• SEVOFLURANE – Excellent choice for rapid and smooth inhalational induction.

( b\c of non pungency and rapid increases in alveolar anesthetic conc.)

VOLATILE ANESTHETICS

Halothane Isoflurane Sevoflurane

Pleasant Smell + + - - + -

MAC 0.75% 1.2% 2%

HR ↓ arrhythmia ↑ or no change minimal

SVR + - - - - -

Contractility - minimal - minimal

BP - - - - -

CO ↓ + or minimal + or minimal

Catachol. sensitisation + + + - -

Bronchi Dilatation less less

Uterus Relaxation less less

Hepatic Tox. + - - - -

Renal Tox. - - - +

• Neuromuscular Blocking Agents( Ms relaxants) ( no anesthesia, amnesia or analgesia)

• Depolarizing Nondepolarizing Acetyl-choline competitive antagonist receptor agonistNondepolarizing Muscle relaxants are not significantly

metabolized ( except mivacurium metabolized by pseudocholinestrase & atracurium – metabolized by hofmann elimination and ester hydrolysis )

Need reversal agents ( Cholinesterase inhibitors) that inhibit acetylecholinesterase enzyme activity.

Reversal Agents

• Cholinesterase inhibitors ( Anticholinesterse)

• Characteristics of cholinergic receptors

Nicotinic Muscarinic• Location Autonomic Ganglia Glands ( Lacrimal

Sympathetic & salivary, gastric)

parasympathetic Smooth muscle

ganglia (Bronchial, GIT,

Skeletal muscle bladder, bld vessels)

Heart(SA node,AV node)• Agonists Acetylcholine Acetylcholine

Nicotine Muscarine• Antagonist N D P M relaxants Antimuscarinics

( Atropine, Scopolamine,

Glycopyrrolate)pshm.edu@hotmail.com

• RECOVERY :

Titrate : Reversal : (Muscle relaxant)

Atropine + Neostegmine

opiate : Nalaxone

Benzodiazepine : flumazinil

Extubation \ Airway

oxygenation

Consciousness

Pharmacological character of anticholinerg. Dg

Atropine Scopolamine Glycopyrrolate

Tachycardia +++ + ++

Bronchodilat. ++ + ++

Sedation + +++ 0

Antisialagogue ++ +++ +++

effect

Post- Operative Care :

R. Room : A. Airway, recovery position

C. CVS : Consciousness

Analgesia

MONITORING

COMPLECATION IN THE RECOVERY ROOM HYPOTENTION-HYPERTENSION-ARRHYTHMIA

RESPIRATORY : Airway Obstruction, Hypoxia, Hypoventilation

Delayed recovery

Complication in recovery room

CVS : Hypotension – hypertension – arrhythmia

Respiratory : Airway obstruction, Hypoxia,

Hypoventilation

Delayed Recovery

RECOVERY :

Stop Anaesthesia

# Titrate : Reversal : MR : Prostig. + Atropine. Opioids : naloxone

A. Extubation \ Airway B. O2 C. Consciousness

Thank you

Anesthesia Pharmacology

Documents

Basic Principles of Pharmacology · The basic principles of pharmacology are fundamental to an anesthesia provider’s knowledge base. The aim of . this chapter is to provide an overview

13236530 Anesthesia Pharmacology

Oral Surgeon Fee Schedule - Arkansas · 2019-10-01 · 00100 Anesthesia $0.00 00102 Anesthesia $0.00 00103 Anesthesia $0.00 00140 Anesthesia $0.00 00160 Anesthesia $0.00 00162 Anesthesia

Acupuncture Main Channels or Meridians: Visible Surfacesa deeply inserted acupuncture needle, the Research Group of Acupuncture Anesthesia, Institute of Medicine and Pharmacology of

Practical Pharmacology in Regional Anesthesia · PDF file5 Practical Pharmacology in Regional Anesthesia 123 Local Anesthetics Chemical Structure Local anesthetic molecules are comprised

Advanced Cardiovascular Pharmacology Update · Theory evolving regarding ... neurotransmitter acetylcholine on heart rate leading to tachycardia ... during anesthesia and SCIP. Metoprolol

Pharmacology General pharmacology

CLINICAL PHARMACOLOGY REVIEW...OCP Division Division of Clinical Pharmacology II OND Division Anesthesia, Analgesia and Rheumatology Products Sponsor Pfizer, New York, NY Relevant

Surgical Pharmacology and Anesthesia

Pharmacology - Weeblymrskreisel.weebly.com/.../17_pharmacology_wkbk._07.doc · Web view3. Regional anesthesia B. Response to local anesthetic 1. Skin veins dilate 2. Brief sense of

Pharmacology for Anesthesia I Introduction. What is a Drug?

Pharmacology of Local Anesthesia Part I

Cerebral Pharmacology and Anesthesia for Supratentorial Craniotomy

MUSC, D.N., Anesthesia Practice, Post-Baccalaureate, Program … · 2013-06-28 · Advanced Pharmacology: Anesthetic Drugs (4cr) Advanced Principles of Anesthesia Practice (3c1')

Books for Anesthesia and Intensive Careassets.cambridge.org/isbn13/97805219/80203/full... · Pharmacology for Anaesthesia and Intensive Care Third edition Tom E. Peck Royal Hampshire

Essentials of Pharmacology for Anesthesia, Pain Medicine ...978-1-4614-8948-1/1.pdf · Alan vid Da Kaye Adam M. Kaye Richard D. Urman Editors Essentials of Pharmacology for Anesthesia,

Latin American Anesthesiology Congress XX of ... 2017 - Preliminar Program 1… · Regional Anesthesia Spine Pain Symposium Education Airway Workshop TIVA Workshop Clinical Pharmacology

GERERAL ANESTHESIA AND PHARMACOLOGY OF GENERAL ANESTHETICS Amir B. Channa FFARCS,DA(ENG) Department of Anesthesia & Intensive Care King Khalid University

Pharmacology for Anesthesia I

Web viewAmerican Society for Pharmacology and ... Ciceri DP: “Nephrology Consultation”, in Manual of Clinical Anesthesia, 2. nd. ... 25.McLeskey CH, Meyer T