In-Hospital Cardiac Arrest / ALS

Cardiac arrest requires immediate CPR and defibrillation for shockable rhythms (VF/pulseless VT). Follow the ALS algorithm: assess rhythm every 2 minutes, treat reversible causes (4Hs and 4Ts), and give adrenaline 1mg IV every 3–5 minutes…

Resuscitation Council UK ALS Algorithm 2021

The pathway

1 · Confirm cardiac arrest and call arrest team

Unresponsive, not breathing normally → call 2222 (in-hospital)
Start chest compressions immediately: 100–120/min, depth 5–6cm, full recoil
Attach defibrillator as soon as available
Assign roles: compressor, airway, drugs, team leader

2 · Assess rhythm — shockable or non-shockable?

Shockable: VF or pulseless VT → defibrillate immediately (200J biphasic)
Non-shockable: PEA or Asystole → continue CPR, treat reversible causes
Minimise hands-off time — pause only to assess rhythm and deliver shocks
Reassess rhythm every 2 minutes

3 · Shockable rhythm — VF/pVT

Shock 1: 200J biphasic → immediately resume CPR (2 min)
Shock 2: 200J → resume CPR
Shock 3: 200J → resume CPR
After Shock 3: Adrenaline 1mg IV + Amiodarone 300mg IV
Continue: shock → CPR cycle every 2 minutes
Adrenaline 1mg every 3–5 minutes (alternate loops)
Amiodarone 150mg after Shock 5 if refractory VF
Still in VF after 3 consecutive shocks: check pad placement, then change the vector — fresh pads antero-posterior at the next rhythm check. RCUK 2025 does not recommend routine dual sequential defibrillation

4 · Non-shockable rhythm — PEA/Asystole

CPR continuously, interrupt only for rhythm checks
Adrenaline 1mg IV as soon as IV access secured, then every 3–5 minutes
Treat the 4Hs: Hypoxia, Hypovolaemia, Hypo/Hyperkalaemia, Hypothermia
Treat the 4Ts: Tension pneumothorax, Tamponade, Toxins, Thrombosis (PE or MI)

5 · Airway management

Bag-valve-mask (two-person technique) until experienced airway provider available
Supraglottic airway (i-gel) or tracheal intubation once available
Once intubated: continuous compressions + 10 breaths/min
Waveform capnography: confirm tube position and monitor CPR quality (ETCO₂ >10mmHg = adequate compressions)

6 · IV/IO access and drugs

Large-bore IV access immediately
IO access if IV fails — use tibial or humeral route
All drugs flushed with 20ml 0.9% NaCl
Do NOT routinely give calcium, sodium bicarbonate or corticosteroids during arrest (RCUK 2025)
Bicarbonate needs a specific indication — hyperkalaemia or tricyclic overdose. Arrest duration and acidosis alone are not indications

7 · Reversible causes — 4Hs and 4Ts

Hypoxia: ensure effective ventilation with high-flow O₂
Hypovolaemia: IV fluid bolus, MHP if haemorrhage
Hypo/Hyperkalaemia and metabolic: check ABG, calcium gluconate for hyperkalaemia
Hypothermia: warm patient, warm IV fluids
Tension pneumothorax: needle decompression (4th–5th ICS anterior axillary line preferred, or 2nd ICS MCL) then chest drain. Where the skill is available, open thoracostomy is more reliable in an arrest
Cardiac tamponade: pericardiocentesis or thoracotomy
Toxins: specific antidotes — naloxone (opioids), lipid emulsion (local anaesthetic toxicity)
Thrombosis (PE): consider thrombolysis (alteplase 50mg IV); continue CPR for 60–90 minutes post-lysis

8 · Post-resuscitation care (ROSC)

SpO₂ 94–98%, avoid hyperoxia
ETCO₂ target 4.5–6.0 kPa (normocapnia)
SBP ≥100mmHg: IV fluids, vasopressors (noradrenaline) if needed
12-lead ECG: check for STEMI → activate cath lab
Temperature: actively prevent fever — keep ≤37.5°C for at least 72h in patients who stay comatose. Routine cooling to 33°C is no longer recommended (TTM2); what matters is that they do not become pyrexial
ITU transfer for monitoring and organ support
Glucose 6–10 mmol/L: treat hypo/hyperglycaemia

Drugs

Drug	Dose	Route	Notes
Adrenaline (epinephrine)	1mg IV	IV/IO	Every 3–5 minutes (alternate 2-min loops). Shockable: after 3rd shock. Non-shockable: immediately. Flush with 20ml NaCl.
Amiodarone	300mg IV	IV/IO	After 3rd shock in VF/pVT. Second dose 150mg after 5th shock if refractory. Dilute in 5% dextrose.
Sodium bicarbonate 8.4%	50ml IV	IV	Not routine in arrest (RCUK 2025). Specific indications only: hyperkalaemia-induced arrest, or tricyclic overdose. Arrest duration and acidosis alone are not indications.
Calcium chloride 10%	10ml IV	IV	The preferred calcium salt in arrest and peri-arrest (UKKA 2023). For hyperkalaemia, hypocalcaemia, or calcium channel blocker toxicity. Outside arrest use calcium gluconate 10% 30ml over 10 min.
Alteplase	50mg IV	IV	Suspected massive PE causing arrest. Continue CPR 60–90 min post-thrombolysis. Give heparin after.
Noradrenaline	0.05–1 mcg/kg/min	IV infusion (ITU)	Post-ROSC vasopressor. Target MAP ≥65mmHg / SBP ≥100mmHg. Central line preferred.

When to escalate

Refractory VF (>3 shocks) — change the defibrillation vector to antero-posterior pads; amiodarone; correct reversible causes,Suspected PE causing arrest — thrombolysis (alteplase 50mg IV); continue CPR 60–90 min,Post-ROSC STEMI — emergency cath lab activation, cardiology consult,Post-ROSC coma — ITU for temperature control (prevent fever, target ≤37.5°C) and neuroprognostication,Prolonged arrest / ROSC with haemodynamic instability — ITU + vasopressors + organ support,Arrest in pregnancy — consider perimortem caesarean section at 4 minutes if ≥20/40 gestation

Reference: Resuscitation Council UK ALS Guidelines 2021 / ERC Guidelines 2021

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