Prac Class 1 - Greencross Vets · luer lock 3-way stopcock or lure ... catheter with hep saline Slide the catheter up ... Total peripheral resistance

Goals Nasal oxygen catheter

Difficult intubation: alternative techniques

Alveolar recruitment manoeuvers

Management of oesophageal reflux

Venous cut-down

Arterial catheterisation & arterial blood sampling

Using anaesthetic monitors

Estimating fluid responsiveness: Dynamic measures of Systemic venous filling pressure (Not CVP)

History tracheotomy was portrayed on Egyptian tablets dated back to 3600 BC

1543 Vesalius passed a reed into the trachea of a dying animal whose thorax had been opened, and maintained ventilation by blowing into the reed intermittently.

1546, the Italian physician Antonio Brasavola reintroduced tracheostomy in humans by performing the first documented case of a successful tracheostomy (Fig. 4) in a patient with tonsillar obstruction.

1733 Hales: First direct blood pressure measurement (horse)

1828 Poiseuille won the gold medal of the Royal Academy of Medicine for his doctoral dissertation on the use of a mercury manometer for the measurement of direct arterial blood pressure.

1863 First systemic study, description and interpretation of intracardiac pressure recordings (horse)

1952 Clinical use of CV Catheter in man

1970 Dr Swan & Ganz: Balloon catheters to measure RAFP, LVPWP, CO

Nasal oxygen catheters

Place a few drops of lidocaine 2% in one of the nostrils

Measure and mark a soft thin catheter the distance from the nose to the medial canthus

Open the external nares by holding the nasal plannum dorsally

Introduce the catheter ventrally and medially along the floor of the nose

Secure the catheter to the side of the nose with superglue, tissue glue, skin staple or suture

100-150 ml/kg/min O2 via nasal oxygen

catheter will provide 30%-50%

humidified O2

Treatment of Ventilatory Failure

Effect of enriching inspired oxygen concentration during hypoventilation in man

From Nunn’s Applied Respiratory Physiology

5th Edit Lumb AB

A small increase in FIO2 will maintain a normal PAO2

even with large falls in ventilation

Difficult intubation

Strategies in management of respiratory emergencies

- identification of miss intubation

- facilitation of intubation

- alternative routes for intubation

- emergency airway access

Identification of miss intubation

- Lack of humidification within ET tube on expiration

- Absence of normal sound from ET tube with chest

compression

- Failure to inflate chest on positive pressure breath

- ETCO2

Managing Difficult intubation

- Key is to minimising complications

- Maintenance of oxygenation

- Prevention of trauma

- Alternative or backup plan

- Termination of the procedure

- Managing difficult intubations

expected difficult intubation - ability to prepare

unexpected difficult intubation - always be prepared


Expected difficult intubation

Brachycephalic breed, obesity

Mass/swelling obstructing the pharynx

Macroglossia

Trismus


Pre-oxygenate everything possible (without undue stress)

Appropriate laryngoscope for species, breed and size

Experienced assistant to extend the head and neck

Protocol for reflux or vomiting

Use of stylet or boogie

Endoscopically assisted

Tracheal catheter oxygenation

Invasive retrograde intubation

Emergency tracheotomy



Stylet intubation


Stylet intubation


Transtracheal catheter

For emergency oxygenation

Place a 14G IV catheter over the needle straight into the

trachea

Withdraw needle and connect O2 to the catheter

Cannot ventilate the patient but will maintain oxygenation

whilst a better alternative is implemented


Retrograde

intubation

South Tamworth Animal Hospital

Rabbits

Weight: 1.5-5 kg

Life span: 5-10 yrs

Temperature: 38 - 40 oC

Heart rate: 200-300 beats/min

Blood volume: 60 ml/Kg

Tidal volume: 4-6 ml/kg

Resp rate: 32-65/min


Rabbits

Pre-anaesthesia:

Wrap the rabbit

Clip fur from ears

artery central

veins marginal


Rabbits

Apply EMLA

cream & leave

for 15-30 min


Rabbits

Catheterise ear vein

24-22 g Optiva catheter


Rabbits

Attach bung


Rabbits

Catheterise ear vein

24-22 g Optiva catheter

Attach bung

Tape to folded ear


Rabbits

Midazolam

0.25 - 0.5 mg/kg IV

0.5 - 2 mg/kg SC


Rabbits

Pre-oxygenate


Rabbits

Give induction drug IV

slowly “to effect”

Alfaxalone 4mg/kg (in

syringe) or

Propofol 8 mg/kg (in

syringe)


Rabbits

Tracheal intubation

Equipment:

otoscope & specula

4% topical lignocaine

Cass needle

2.5,3.0,3.5mm ETTubes

plain forceps

4FG infant feeding tube

scissors

cloth tape


Rabbits

Tracheal intubation

Position in sternal

recumbency

loop around upper incisors

Grasp tongue and draw

forward


Rabbits

Tracheal intubation

Visualise larynx with

otoscope (may need to

displace soft palate)


Rabbits

Tracheal intubation

Visualise larynx (may need

to displace soft palate)

Spray larynx with 0.2 ml 4%

lignocaine (Cass needle)


Rabbits

Tracheal intubation

Visualise larynx (may need

to displace soft palate)

Spray larynx with 0.2 ml 4%

lignocaine (Cass needle)

Re-apply facemask for

30 sec.


Rabbits

Tracheal intubation

Cut luer end from

feeding tube

Intubate trachea with

rounded end of

feeding tube


Rabbits

Tracheal intubation

“Railroad” ET tube

over the feeding

tube and gently

manipulate through

the larynx


Rabbits

Tracheal intubation

“Railroad” ET tube over the feeding tube and gently manipulate through the larynx

Confirm correct placement of ET tube (capnography, air movement or chest inflation)

Connect to Humphrey’s ADE, Bain or “T” piece patient breathing system

What are your management options to maintain

oxygenation during surgery: Alveolar

recruitment manoeuver

Alveolar recruitment manoeuver

Downside atelectasis occurs quickly

Progressive deterioration in gas exchange

Venous admixture, increasing shunt fraction, ↓ SpO2

Alveolar recruitment manoeuver

ARM: 30-40cm H2O for 20-30 secs

Reflux Gastro-oesophageal reflux during anaesthesia in the dog: the effect of

preoperative fasting and premedication.

AD Galatos & D. Raptopoulos Vet Record 1995;137:479-483

Lower oesophageal reflux was monitored in 240 anaesthetised dogs.

The incidence of gastro-oesophageal reflux was 16.3 %

Most of the reflux episodes occurred shortly after the induction of anaesthesia.

The refluxate was nearly always acid (pH < 4.0),

In 10.3% of the cases it was alkaline (pH > 7.5)

Gastric contents of pH below 2.5 were refluxed on 19 occasions (7.9%)

Regurgitation occurred in only one dog.

Prolonging preoperative fasting was associated with an increased incidence of reflux and increased gastric acidity.

Regurgitation

Regurgitation

o Head down tilt

o Check cuff is inflated correctly

o Ideally check pH with urine Dipstix

o Clean pharynx with gauze swabs

o Place oesophageal tube

o Irrigate oesophagus with 0.3M Na Citrate 1-3ml/kg

whilst slowly extracting the stomach tube

o Repeat clean pharynx

Regurgitation

Head down tilt

Oesophageal tube and

0.3M Na Citrate

Technique for venous cut down

1

Expose

2

2 loops

3

Incise

transversely

4

Insert

cannula

5

Suture

& secure

Direct arterial catheterisation

Dr. Bob Stein

Veterinary Anesthesia & Analgesia

Support Group

Practical Information for the

Compassionate Veterinary Practitioner


Basic needs for arterial blood

pressure monitoring include freshly

mixed heparinized saline, IV

catheters (20 GA, 22 GA, 24 GA),

luer lock 3-way stopcock or lure

lock T-port, small diameter

pressure tubing, and pressure

transducer.

In addition, you will need a direct

blood pressure monitor and the

appropriate cable for the

transducer used.


This is the basic

sequence; what

connects to what.


Remove the catheter end-cap and flush the stylet within the catheter with hep saline

Slide the catheter up the stylet to flush the inner catheter wall and facilitate catheter advancement once introduced into the artery


Flush the

3-way

stopcock

filling both

arms.


Next fill the transducer with hep saline making sure no air bubbles are present. Initially flush through the perpendicular arm of the 3-way stopcock


Then attach the pressure tubing to the stopcock and transfer the hep saline syringe to that perpendicular port. Rotate the valve to direct flow into the tubing and flush with hep saline. Now you are ready to place the arterial catheter. Keep all ports and fittings covered with sterile caps.


The most common

site for canine direct

arterial blood

pressure monitoring

is the dorsal pedal

artery. This artery is

usually palpable

over the dorsum of

the metatarsal area


A small area

is clipped and

prepped over

the arterial

site.


The 3-way

stopcock and

tubing are

attached and

secured into

place. .


The opposite end of the tubing is attached to the pressure transducer which should already be secured to the monitor cable. If the patient connections are not adequately secured large volume blood loss can occur in a short period of time. This is especially concerning as this site is usually tucked away under draping out of site.


Now zero the arterial pressure trace by:

Rotate the valve to expose the transducer chamber to normal atmospheric pressure (simultaneously occluding the arterial line.

The transducer should be zeroed and maintained at heart base level.


Then press the zero button

The display should read zero.

Attach a hep saline syringe to the open 3-way valve port at the transducer, rotate the valve to close flow to the transducer and flush the tubing and catheter. Then rotate the 3 way valve to allow continuity between transducer chamber and the arterial catheter.

Direct arterial catheterisation The transducer should be zeroed and maintained at heart base

level (sternum level if in lateral, point of the shoulder if in dorsal or

ventral recumbancy) for the most accurate results.

The fluid line needs to be flushed periodically (and whenever the

pulse wave dampens) to avoid clot development at the catheter site.

If the flush fluid flows easily but very low pressures register

immediately check the arterial catheter site for poor

connections/haemorrhage.

Be conscious of hep saline fluid volumes administered during

flushing - especially in smaller or CV compromised patients.

Indirect BP measurement

Blood pressure measurement

Direct BP vs Indirect BP (NIBP)

o Gold standard" for accuracy vs. Good accuracy (<+6mmHg) depending on technique and provided no extremes of hypertension and particularly hypotension

o Continuous measurement vs. Intermittent measurement

o Requires surgery to place catheter vs. No surgery required

o Periodic flushing of catheter required vs. Periodic inflation/deflation of cuff required

Blood pressure measurement

Provides information about

Adequacy of blood volume in relation to the size of the

vascular bed (but not always)

Cardiac Output (but not always)

Total peripheral resistance (but not always)

Magnitude of hypo & hypertension

Depth of anaesthesia

Pulse oximeter

SpO2 the % oxyhaemoglobin in arterial blood

SpO2 is determined by adequacy of both

respiratory function & circulatory function

Only processes pulsatile signal, hence gives PR

Often false alarm

Plethysmograph to quickly assess signal quality

Non-invasive, quick and simple to use

Greatest advance in patient monitoring

Interpretating SpO2 Step 1 = check signal quality

If SpO2 = 90 there is a serious problem

If SpO2 = 80 there is a critical problem

Provided the [Hb] is normal,

in the range of SpO2 80-90

the O2 content has not fallen

that much.

But the PO2 has fallen

seriously, thus also the

diffusion gradient driving O2

into tissues

= serious hypoxia

SpO2 plethysmograph trace

Capnography

Provides an accurate measurement of the adequacy

of ventilation

Hence,

Hyperventilation results in low ETCO2

Underventilation results in high ETCO2

And

Rebreathing CO2 means the base line

does not return to 0

Anaesthetic agent monitoring

Temperature

Documents

Prac Class 1 - Greencross Vets · luer lock 3-way stopcock or lure ... catheter with hep saline Slide the catheter up ... Total peripheral resistance