Key Facts

ALS provides a systematic framework for managing cardiac arrest using a team-based approach. It builds on basic life support (BLS) by adding defibrillation, drug therapy, advanced airway management, and systematic identification and treatment of reversible causes.

Epidemiology

ALS-trained healthcare professionals manage approximately 50,000 cardiac arrests per year in the UK (combined OHCA and IHCA). ALS training is mandatory for most hospital doctors in the UK. Successful resuscitation depends on the entire chain of survival, not any single intervention.

Aetiology

Cardiac arrest may result from primary cardiac causes (acute coronary syndromes, arrhythmias, structural heart disease) or non-cardiac causes (respiratory failure, sepsis, haemorrhage, PE, metabolic derangement, toxins). The approach is the same regardless of cause, with specific attention to identifying and treating reversible factors.

Pathophysiology

The ALS algorithm is based on the principle that early defibrillation is the only intervention proven to improve survival from VF/pVT, while for non-shockable rhythms, treating the underlying cause is paramount. Adrenaline increases coronary and cerebral perfusion pressure during CPR. Amiodarone stabilises the myocardial membrane in refractory VF.

ALS Assessment

• Confirm cardiac arrest: Unresponsive, not breathing normally, no pulse
• Attach defibrillator: Assess rhythm — shockable vs non-shockable
• Begin CPR: 30:2 initially; continuous once advanced airway placed

Shockable Rhythm Protocol

1. Single defibrillation (150-200J biphasic)
2. Immediately resume CPR for 2 minutes
3. Rhythm check — shock again if VF/pVT persists
4. After 3rd shock: Adrenaline 1mg IV + Amiodarone 300mg IV
5. Continue cycle; Adrenaline every 3-5 min; Amiodarone 150mg after 5th shock

Non-Shockable Rhythm Protocol

1. Begin CPR, secure IV access
2. Adrenaline 1mg IV as soon as possible
3. Continue CPR for 2 minutes, then rhythm check
4. Adrenaline every 3-5 min
5. Actively search for and treat reversible causes

Red Flags

• CPR interrupted for >10 seconds — no-flow time increases brain injury
• Failure to recognise PEA with treatable cause — delays definitive treatment
• Team not considering 4Hs/4Ts — missed reversible causes
• Post-ROSC hypoxia and hypotension — worsen neurological outcome

Bedside

• Cardiac rhythm monitoring: Continuous — guide shockable vs non-shockable pathway
• Capnography (ETCO2): Confirms ETT placement; guides CPR quality (target ETCO2 >2.7 kPa); sudden rise = ROSC
• Point-of-care USS: During rhythm check (<10 sec) — cardiac standstill, tamponade, RV dilatation
• Blood gas (ABG/VBG): K⁺, pH, lactate during arrest

Bloods

• ABG: Immediate — potassium, pH, lactate, haemoglobin
• Blood glucose: Hypoglycaemia is a treatable cause
• U&Es: Post-ROSC renal function and electrolytes
• Troponin: Post-ROSC cardiac assessment

Imaging

• 12-lead ECG: Post-ROSC — STEMI diagnosis
• CXR: Post-ROSC — ETT position, complications
• CT: If cause of arrest unclear (head, chest, abdomen)

Special Tests

• Echocardiography: Post-ROSC cardiac function assessment
• Coronary angiography: If ACS suspected
• CT head and EEG: For neuroprognostication (≥72h post-arrest)

Non-pharmacological

• Team leadership: Designated team leader; clear role allocation
• High-quality CPR: Continuous compressions (100-120/min, 5-6cm), rotate compressors every 2 min
• Defibrillation: Biphasic 150-200J; minimise pre-shock pause (<5 sec)
• Advanced airway: ETT or SGA; once placed, continuous compressions (10 ventilations/min)
• IV/IO access: Peripheral IV preferred; IO if IV access fails within 2 min

Pharmacological

• Adrenaline 1mg IV: Non-shockable — immediately; Shockable — after 3rd shock; then every 3-5 min
• Amiodarone 300mg IV: After 3rd shock; 150mg after 5th shock
• Lidocaine 1mg/kg IV: Alternative to amiodarone if unavailable
• Sodium bicarbonate 50mmol (50mL of 8.4%): Consider for severe acidosis, hyperkalaemia, or TCA overdose
• Calcium chloride 10mL 10% IV: For hyperkalaemia, hypocalcaemia, or calcium channel blocker overdose
• Magnesium 2g (8mmol) IV: For torsades de pointes or hypomagnesaemia
• Thrombolysis (alteplase 50mg IV): For suspected massive PE — continue CPR for 60-90 min after

Surgical/Interventional

• Emergency thoracotomy: Penetrating chest trauma with arrest
• Pericardiocentesis: Cardiac tamponade
• Needle decompression → chest drain: Tension pneumothorax
• ECPR (extracorporeal CPR): For refractory cardiac arrest in selected patients

Referral Criteria

• All ROSC patients — ICU for post-resuscitation care
• STEMI post-ROSC — emergency PCI
• Refractory VF — consider ECPR if available
• Survivors — cardiac assessment and ICD consideration

• OHCA VF survival: ~25-30% with bystander CPR and early defibrillation
• OHCA PEA/asystole survival: <5%
• IHCA overall survival to discharge: ~23-25%
• Duration of CPR: Survival decreases with duration but ROSC has been reported after >60 min in hypothermic or toxicological arrests
• Neurological outcome: ~80% of survivors achieve CPC 1-2 (good/moderate outcome)
• Targeted temperature management: TTM2 trial showed no benefit of 33°C over 36°C, but both better than uncontrolled hyperthermia

4Hs and 4Ts — Reversible Causes

ALS Drug Summary