Write a short note on cardiac arrest and cardiopulmonary resuscitation.

Definition

Cardiac arrest is the abrupt cessation of effective cardiac mechanical activity, confirmed by unresponsiveness, absent normal breathing (or only agonal gasps), and absent central pulse. Without immediate intervention, irreversible brain injury begins within 4–6 minutes.

RHYTHMS of Cardiac Arrest

VF is the commonest initial rhythm in out-of-hospital arrest from ischaemic heart disease, and carries the best prognosis — but it degenerates to asystole with time, which is why early defibrillation is the single most important determinant of survival.

REVERSIBLE CAUSES — THE 4 Hs AND 4 Ts

The Chain of Survival

1. Early recognition and call for help

2. Early high-quality CPR

3. Early defibrillation

4. Post-resuscitation care

Basic Life Support

1. Ensure safety of rescuer and victim.

2. Check responsiveness — shake and shout.

3. Open the airway (head tilt–chin lift; jaw thrust if cervical spine injury is suspected) and check breathing for no more than 10 seconds. Agonal gasping is NOT normal breathing and must not delay CPR — this is a common and fatal error.

4. Call for help and get a defibrillator.

Start Chest Compressions Immediately:

• Centre of the chest, lower half of the sternum
• Depth 5–6 cm; rate 100–120 per minute
• Allow FULL chest recoil between compressions
• MINIMISE INTERRUPTIONS — aim for a chest compression fraction above 60–80%
• Change the compressor every 2 minutes to prevent fatigue-related deterioration in quality

6. Compression:ventilation ratio 30:2 for untrained or single rescuers without an advanced airway; continuous compressions with asynchronous ventilation once an advanced airway is placed.

7. Compression-only CPR is acceptable and encouraged for untrained bystanders and where there is reluctance to give mouth-to-mouth — it is far better than no CPR.

Advanced Life Support

Shockable rhythm (VF/pVT):

• Defibrillate immediately — biphasic energy per device recommendation — and resume compressions immediately without a pulse check.
• 2 minutes of CPR, then rhythm check and further shock if indicated.
• Adrenaline after the third shock, then every 3–5 minutes.
• Amiodarone after the third shock (lidocaine as an alternative).
• Continue the 2-minute cycles; treat reversible causes throughout.

Non-shockable rhythm (PEA/asystole):

• Adrenaline as soon as possible, then every 3–5 minutes.
• CPR in 2-minute cycles with rhythm checks.
• Aggressively identify and treat the 4 Hs and 4 Ts — this is where survival lies, since there is no shock to give.

Airway and adjuncts: bag-mask ventilation initially; supraglottic airway or tracheal intubation by a skilled operator without interrupting compressions; waveform capnography — which confirms tube placement, monitors CPR quality (a rising ETCO₂ indicates better perfusion), and provides the earliest sign of return of spontaneous circulation (a sudden rise in ETCO₂).

Access: intravenous, or intraosseous if intravenous access is delayed or impossible.

POST-RESUSCITATION CARE (after return of spontaneous circulation)

• Airway and ventilation: aim for normoxia (SpO2 94–98% — AVOID hyperoxia, which worsens reperfusion injury) and normocapnia.
• Circulation: treat hypotension with fluids, inotropes and vasopressors; 12-lead ECG and urgent coronary angiography with PCI if a coronary cause is suspected.
• Targeted temperature management and strict avoidance of fever — hyperthermia after arrest worsens neurological outcome.
• Control seizures; maintain normoglycaemia; correct electrolytes.
• Neurological prognostication is deferred for at least 72 hours (and longer if sedation or hypothermia has been used) — early pessimism is unreliable and self-fulfilling.
• Identify and treat the underlying cause; consider ICD for survivors of VF/VT arrest not due to a reversible cause.

When to Stop

Decisions consider the duration of arrest, downtime before CPR, the initial rhythm, the response to resuscitation, end-tidal CO₂, comorbidity and the underlying cause. Prolonged resuscitation is justified in hypothermia, drowning, drug overdose, pregnancy and in children — and in thrombolysis for suspected pulmonary embolism, where CPR may be continued for 60–90 minutes.