CPR

Question 1

Give some examples of causes of cardio-pulmonary arrest (CPA)

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

Question 2

What does CPA lead to?

Answer 2

Acute failure of cardio-respiratory systems
- Lack of oxygen delivery to tissues (DO2)
- Unconsciousness & systemic cellular death
- Cerebral hypoxia (brain death within 4 to 6 minutes)

Question 3

What are some common signs of CPA

Answer 3

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 4

What is basic life support?

Answer 4

Question 5

What chest compression technique is used in small animals?

Answer 5

Cardiac pump

• Focus on ventricles of 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 6

What chest compression technique is used in larger animals?

Answer 6

Thoracic pump

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

Question 7

Describe internal cardiac compressions

Answer 7

• Trans-diaphragmatic or Lateral-thorax approach.
• Better than external compressions
• Takes time unless already in surgery
• Training required.
• Post arrest care more complex & intensive

Question 8

Describe large animal CPR

Answer 8

Requires many people, exhausting

Methods:
- Conga line technique → people take turns throwing body weight onto caudo-dorsal lung field
- Jump/knee onto chest for 2 minutes

Aim for highest compression rate you can

Animal needs to be in lateral recumbency on solid surface

Question 9

Describe ventilation during CPR

Answer 9

1. Clear airway
   - Manually remove obstructions
   - Suction for blood/vomit if needed
2. Secure airway
   - Orotracheal intubation (ET tube)
   - Emergency Tracheostomy
3. Ventilation techniques
   - Positive Pressure Ventilation (PPV) required
   - ET tube connected to AMBU bag, anaesthetic machine, or demand valve (large animal)
   - Mouth-to-snout/nose/mask (zoonotic risk)

Key parameters:
- Max inspiratory pressure: 40 cmH2O
- Tidal volume: 10 ml/kg
- Ventilation rate: 10 breaths/minute

Question 10

How do you perform an emergency tracheostomy

Answer 10

3-5cm midline incision & blunt dissection

Trachea entered 2-4cm caudal to larynx, ET tube placed between rings

Takes time….

Large Guage Needle with syringe & ET tube connector for instant access

Question 11

What is involved in advanced life support? (after BLS)

Answer 11

Question 12

Describe monitoring during CPR

Answer 12

Capnography (ETCO2):
- Measures perfusion, >18 mmHg = good compressions.

ECG:
- Assesses heart rhythm (shockable vs. non-shockable). - Does not indicate cardiac output

Other methods:
- SPO2% - not very reliable
- Blood gas analysis
* Venous blood gas samples preferred
- Blood pressure – not very reliable

Question 13

What changes are we looking for when monitoring a patient during CPR?

Answer 13

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 14

Describe vascular access during CPR

Answer 14

IV (Cephalic, Saphenous, Jugular):
- First choice
- Difficult during CPR due to movement
- Jugular venous cannula ideal but at risk of thrombophlebitis

Intraosseous (IO):
- Used in small animals, collapsed patients, birds.
- Sites: greater tubercle of humerus, tibial crest, trochanteric fossa (femur)
- as rapid as peripheral veins
- in neonates can be achieved with needle, however in older patients with mature cortex drill is needed

Intratracheal (IT):
- Requires dilution
- Use urinary catheter inserted beyond carina
- chest inflations will distribute drugs
- higher doses needed

Question 15

What reversals (antagonists) can be used during CPR?

Answer 15

Atipamezole → Reverses alpha-2 agonists (e.g. medetomidine).

Naloxone → Reverses opioids (e.g. methadone).

Flumazenil → Reverses benzodiazepines (e.g. midazolam).

Check anaesthetic records before administering

Question 16

Describe what to do in case of a VF or pulseless VT during CPR

Answer 16

Shockable

These rhythms less responsive to BLS

Aim: Convert to asystole or PEA & then carry on with BLS

Methods:
- Defibrillation
- Precordial thump
- Drug therapy:
* Lidocaine (sodium channel blocker)
* Amiodarone (potassium channel blocker)
* Esmolol (beta blocker)

Question 17

What are asystole & PEA

Answer 17

Asystole = flat line.

Pulseless Electrical Activity = can look normal – don’t get caught out.

More responsive to CPR -> drug therapy to augment this.