CPR

Question 1

list causes of cardio-pulmonary arrest

Answer 1

• anaesthetic complications
• severe trauma
• severe electrolyte disturbances
• hypovolemia
• vagal stimulation
• cardiac arrhythmias
• cardiorespiratory disorders
• debilitating or end-stage diseases
• Myocardial hypoxia
• Drugs and toxins
• pH abnormalities
• Electrolyte disturbances
• Temperature problems
• lack of oxygen delivery to tissues
• unconciousness and systemic cellular death
• cerebral hypoxia (brain dead within 4-6 mins)

Question 2

list signs of cardiopulmonary arrest

Answer 2

• Loss of consciousness
• Apnoea or agonal gasping
• No corneal reflex or palpebral reflex
• No heart sounds
• No palpable pulse
• Central eye position
• Pupils fixed and dilated
• Bleeding stops at surgical site
• Mucous membrane grey/blue/white
• CRT altered (can be normal!)
• Dry cornea
• General muscle flaccidity
• ECG arrhythmias (VF, VT, Asystole, PEA/EMD

Question 3

outline the CPR initial assessment algorithm

Answer 3

Question 4

what does basic life support entail

Answer 4

• chest compressions
• ventilation

Question 5

outline the CPR algorithm

Answer 5

Question 6

what kind of chest compressions do you do in cats, small dogs and keel chested dogs

Answer 6

cardiac pump

Question 7

how do you do chest compressions

Answer 7

Question 8

where do you do chest compressions on large dogs

Answer 8

widest part of chest

Question 9

how do you perform cardiac pump

Answer 9

• You are focusing on the ventricles of the heart, wrapping your hands around.
• Ventral 1/3 thorax, ribs 3-6.
• 100-120 bpm for 2 minutes.
• Less effective with obesity, pericardial effusion, pneumothorax.

Question 10

how do you perform thoracic pump

Answer 10

• Focus on the thorax, not the heart.
• Works through changing intrathoracic pressures.
• Lateral recumbency - widest part of the chest, compress to 1/3-1/2 the width.
• In Dorsal recumbency – ¼ width.
• 100-120 bpm for 2 minutes.

Question 11

how do you perform intrathoracic pump

Answer 11

Trans-diaphragmatic or Lateral-thorax approach.
Better than external compressions
55% cardiac output vs 22%
Better survival in experimental studies (dogs)
Takes time unless already in surgery.
Training required.
Post arrest care more complex and intensive

Question 12

how do you perform CPR on large animals

Answer 12

• Need LOTS of people.
• Exhausting!
• Aim for the highest compression rate you can.
• Two potential options:
• All compressors line up then -> throw whole body onto caudo-dorsal lung field and immediately switch with the next person.
• i.e. a conga line of compressions!
• Or
• One person at a time for two minutes jumping up and down/kneeing the horse in the chest.
• Horse needs to be in lateral recumbency on solid surface
• Success reported in the literature is limited:
• Three persons (weighting 60, 80, and > 90 kg, respectively) rotated every 2 min to perform the external massage. The third heavier operator performed massage by rhythmically and energetically sitting on the horse’s thorax.

Question 13

how will you secure an airway

Answer 13

First assess the airway:
* May need to clear this manually e.g a tennis ball
* Or with suction e.g. blood or vomit

Then secure control:
* Orotracheal intubation with ET tube.
* Or
* Emergency Tracheostomy
* 3-5cm midline incision and blunt dissection.
* Trachea entered 2-4cm caudal to larynx, ET tube placed between rings.
* Takes time….
* Large Guage Needle with a syringe and ET tube connector for instant access.

Question 14

how do you ventilate during CPR

Answer 14

Positive Pressure Ventilation (PPV) is required:

ET tube connected to AMBU Bag, Anaesthetic machine or a demand valve (Large Animal).
Or
Mouth-to-snout/nose/mask ventilation.
Be careful – possible zoonotic risk

Be careful – you are in full control of the lungs -> maximum inspiratory pressure of 40cmH2O

Tidal volume – approx. 10ml/kg
Iatrogenic barotrauma, pulmonary haemorrhage or pneumothorax is easy to do.

Ventilation rate – 10 breaths per minute

10 in 10

Question 15

advanced life support includes:

Answer 15

• monitoring
• obtaine vascular access
• administer reversals

Question 16

what should be monitored during CPR

Answer 16

• capnography
• ECG
• SPO2
• Blood gas analysis
• blood pressure

Clinical changes:
* Pulses – but difficult to palpate!
* Mucous membrane colour
* Eye position changes (central  ventromedial)
* Pupil changes size
* Palpebral, corneal, gag reflex may be noticed
* Breathing or chest movements (twitches) resume
* Lacrimation
* Animal regains consciousness

Question 17

good compressions are indicated by a reading of what on a capnograph

Answer 17

> 18 mmHg

Question 18

what does a capnograph measure during CPR

Answer 18

perfusion, movement of carbon dioxide from the tissues to the lungs

Question 19

what EtCO2 do you expect in a live animal

Answer 19

40mmHg

Question 20

what does ECG tell you during CPR

Answer 20

Allows rhythm assessment – is it a shockable rhythm or not – VF/pulselessVT
Does NOT tell you about perfusion/cardiac output

Question 21

what are the options for vascular access curing CPR

Answer 21

Cephalic, Saphenous or Jugular (IV)
* Route of choice for drugs & fluids
* Tricky during CPCR because of the movement
* Jugular venous canula is ideal for administration but risk of thrombophlebitis, other veins not as effective but you can ‘flush’ the drug centrally

Intraosseous route (IO)
* As rapid as peripheral veins
* Useful in small animals, very collapsed animals and birds
* Sites used include the greater tubercle of the humerus, tibial crest or trochanteric fossa of the femur
* In neonates can be achieved with a needle, however, in older patients with a mature cortex, a drill is often needed.

Intratracheal (IT)
* Dilute and use urinary catheter inserted beyond carina
* Chest inflations will distribute the drugs
* Higher doses are needed

Question 22

youve given medetomidine and need to reverse it during an emergency. what will you use

Answer 22

atipamezole

Question 23

youve given methadone but need to reverse it during an emergency. what do you use

Answer 23

naloxone

Question 24

youve given midazolam but need to reverse it in an emergency. what do you use

Answer 24

flumazenil

Question 25

how do you convert VF and pulseless VT to a rhythm you can manage with BSL

Answer 25

* Defibrillation * Pre-cordial thump * Medical conversion Sodium channel blocker – lidocaine Potassium channel blocker – amiodarone Beta blocker - esmolol

Question 26

what is PEA

Answer 26

pulseless electrical activity (can look normal)

Question 27

what drugs can be given if the patient has asystole of PEA and why

Answer 27

Adrenergic agonist – α and β receptors. * Positive inotrope and chrono trope. * Increases myocardial oxygen demand. * α adrenergic effects include peripheral vasoconstriction (vasopressor) * ‘Shunts’ blood from the periphery to the heart, brain and lungs. * Low dose adrenaline is recommended (0.01mg/kg) * Given every 3-5 minutes i.e. every other 2-minute cycle * High dose is no longer recommended (0.1mg/kg) * Pro-arrythmic so avoid initially in VFib/VTach. Vasopressin * Causes peripheral vasoconstriction without deleterious effects on myocardial oxygen demand * Therefore, may be preferable to adrenaline in VFib/VTach * Similar efficacy to adrenaline in dogs (small studies) * Meta-analyses in humans have failed to demonstrate an advantage * More expensive than adrenaline but less than it used to be Atropine * Parasympatholytic * Evidence does not show a clear benefit for repeat dosing now * Theoretically good for patients with high vagal tone – common in veterinary patients * Rabbits can have atropinase as a naturally occurring enzyme so not recommended.

Question 28

how do you know the patient has ROSC

Answer 28

* Capnography – sudden increases in ETCO2 are associated with ROSC * ECG – Return of a normal rhythm is not necessarily supportive – PEA * Return of consciousness/movement/reflexes

Question 29

what do you do post ROSC

Answer 29

* Many patients re-arrest * Respiratory optimisation * Supportive oxygen +/- ventilation if required * Target PaO2 80-100mmHg or SpO2 94-98% * Beware hyperoxia and oxidative damage with reperfusion * Cardiovascular optimisation * If hypotensive – beware fluid overload, so use of vasopressor therapy is sensible * Hypothermia * Can be beneficial to cardiac and neurologic outcomes – re-warm slowly 0.5oC/h

Question 30

outline the post ROSC algorithm

Answer 30