CPR Flashcards
Give some examples of causes of cardio-pulmonary arrest (CPA)
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
What does CPA lead to?
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)
What are some common signs of CPA
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)
What is basic life support?
What chest compression technique is used in small animals?
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
What chest compression technique is used in larger animals?
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.
Describe internal cardiac compressions
- Trans-diaphragmatic or Lateral-thorax approach.
- Better than external compressions
- Takes time unless already in surgery
- Training required.
- Post arrest care more complex & intensive
Describe large animal CPR
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
Describe ventilation during CPR
- Clear airway
- Manually remove obstructions
- Suction for blood/vomit if needed - Secure airway
- Orotracheal intubation (ET tube)
- Emergency Tracheostomy - 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
How do you perform an emergency tracheostomy
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
What is involved in advanced life support? (after BLS)
Describe monitoring during CPR
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
What changes are we looking for when monitoring a patient during CPR?
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
Describe vascular access during CPR
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
What reversals (antagonists) can be used during CPR?
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
Describe what to do in case of a VF or pulseless VT during CPR
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)
What are asystole & PEA
Asystole = flat line.
Pulseless Electrical Activity = can look normal – don’t get caught out.
More responsive to CPR -> drug therapy to augment this.
What is adrenaline/epinephrine & how does it work?
Adrenergic agonist (α & β receptors)
Effects:
- Positive inotrope (contractility) & chronotrope (HR).
- Increases myocardial oxygen demand.
- Vasopressor effect (α receptors): shunts blood to heart, brain, lungs
What are the adrenaline dosage guidelines in cardiac arrest?
Low dose: 0.01 mg/kg (recommended)
Given every 3–5 min (every other 2-min CPR cycle)
High dose (0.1 mg/kg): no longer recommended
Avoid initially in VFib/VTach (pro-arrhythmic risk)
What is Vasopressin & how does it work during cardiac arrest?
Causes peripheral vasoconstriction without increasing myocardial oxygen demand
May be preferable to adrenaline in VFib/VTach
Similar efficacy to adrenaline in dogs
Human meta-analyses show no clear advantage
More expensive than adrenaline, but price has decreased
What is atropine and how is it used in cardiac arrest?
Parasympatholytic (blocks vagal tone)
No clear benefit for repeat dosing in cardiac arrest
Theoretically useful for patients with high vagal tone (common in vet med)
Not recommended in rabbits due to natural atropinase enzyme, which breaks it down
When is fluid therapy recommended or not recommended in cardiac arrest?
Not recommended in euvolemic patients (reduces coronary perfusion)
Only considered in patients with known hypovolemia
What are the key considerations for bicarbonate therapy in CPA?
Metabolic acidosis is common in CPA
Mixed evidence in studies, so only used in prolonged CPA
Suggested for cases of known hyperkalemia
When is calcium (calcium gluconate/chloride) recommended in cardiac arrest?
Not for routine use (no clear benefit)
Consider in known/suspected hyperkalemia
Suggested for known hypocalcemia
Why are glucocorticoids (steroids) not recommended in CPR?
May worsen perfusion, including cerebral perfusion
Only suggested in hypoadrenocorticism or vasopressor-resistant hypotension before death (CIRCI)
What are the key considerations for open-chest CPR?
More effective than external compressions
Resource-intensive, requiring significant effort during CPR & recovery
Considered for intra-thoracic pathology (e.g., tension pneumothorax, pericardial effusion) or if patient is already in surgery
What is ROSC
Return of Spontaneous Circulation
What are the key indicators of ROSC?
Capnography: Sudden increase in ETCO₂
ECG: Normal rhythm may not indicate ROSC (e.g., PEA)
Return of consciousness, movement, or reflexes
What is the key concern in post-ROSC care?
Many patients re-arrest
What is the goal of respiratory optimization in post-ROSC care?
Supportive oxygen +/- ventilation if needed
Target PaO₂ 80-100 mmHg or SpO₂ 94-98%
Beware hyperoxia & oxidative damage from reperfusion.
What cardiovascular considerations are important post-ROSC?
Hypotension is common.
Avoid fluid overload → Use vasopressors if needed
How is hypothermia managed post-ROSC & why?
Can improve cardiac & neurologic outcomes
Rewarm slowly at 0.5°C/hour to avoid complications
What is the post-ROSC algorithm
Designed to reduce stress & allow for sensible decisions
If you are panicking or unsure on what to do next: stop, breathe & read algorithm. This applies during CPR as well
