Cardiac Arrest Management for Paramedics (UK Guide)

Cardiac Arrest Management for UK Paramedics

Cardiac arrest remains one of the most time-critical and high-stakes presentations a paramedic will face in pre-hospital practice. With out-of-hospital cardiac arrest (OHCA) survival rates in the UK averaging around 8–10%, every intervention must be deliberate, evidence-based, and executed with minimal interruption to compressions. This guide outlines the core principles of cardiac arrest management aligned with JRCALC guidelines and UK NHS pre-hospital practice.

Recognition and Scene Safety

Effective cardiac arrest management begins before you touch the patient. On arrival, ensure the scene is safe, don appropriate PPE, and gather a rapid history from bystanders where possible. The key to early recognition is assessing responsiveness and breathing simultaneously — an unresponsive patient with absent or only agonal respirations should be treated as a cardiac arrest until proven otherwise.

Agonal breathing is a common source of confusion for students and newly qualified paramedics. It can present as irregular, noisy gasps and may persist for the first few minutes after cardiac arrest. Do not mistake this for normal breathing — if in doubt, start CPR.

High-Quality CPR: The Foundation of Survival

No drug or advanced intervention has been shown to independently improve neurologically intact survival from cardiac arrest. High-quality CPR remains the single most important intervention you can perform. JRCALC and the Resuscitation Council UK align closely on the key parameters:

• Compression rate: 100–120 per minute
• Compression depth: 5–6 cm in adults
• Chest recoil: Allow full recoil between compressions — avoid leaning
• Compression fraction: Aim for >80% of resuscitation time in compressions
• Ratio: 30:2 until an advanced airway is in place, then asynchronous ventilations at 10 breaths/minute

Rotate compressors every two minutes to maintain quality. Fatigue sets in quickly and significantly degrades compression depth and rate — even when the provider is unaware of it.

Rhythm Recognition and Defibrillation

As soon as your monitor-defibrillator is attached, pause briefly to analyse the rhythm. Cardiac arrest rhythms fall into two categories:

Shockable Rhythms

• Ventricular Fibrillation (VF): Chaotic, disorganised electrical activity with no discernible complexes
• Pulseless Ventricular Tachycardia (pVT): Regular broad-complex tachycardia with no palpable pulse

For shockable rhythms, defibrillation is the definitive treatment. Deliver a single shock, then immediately resume CPR for two minutes without checking the rhythm. Minimise pre-shock and post-shock pauses — each additional second of hands-off time reduces the probability of defibrillation success.

Non-Shockable Rhythms

• Pulseless Electrical Activity (PEA): Organised electrical activity with no palpable pulse
• Asystole: Absent or near-absent electrical activity — always check lead connections before confirming

For non-shockable rhythms, focus shifts to identifying and treating reversible causes while maintaining high-quality CPR.

The 4Hs and 4Ts: Reversible Causes

A structured approach to reversible causes is essential, particularly in PEA arrest where an underlying treatable pathology is often present. Use the 4Hs and 4Ts as your mental checklist:

• Hypoxia — Ensure effective ventilation and oxygenation
• Hypovolaemia — Consider haemorrhage, sepsis, or fluid loss
• Hypo/Hyperkalaemia and metabolic disorders — Relevant in renal patients or those with known electrolyte disturbances
• Hypothermia — "Not dead until warm and dead"; continue resuscitation in drowning or exposure cases
• Tension Pneumothorax — Needle thoracostomy is a key paramedic skill; look for absent breath sounds, tracheal deviation, and preceding trauma
• Tamponade — Rare pre-hospital but consider in penetrating chest trauma
• Toxins — Opioid overdose causing arrest responds to naloxone; other toxidromes require specific consideration
• Thrombosis — Both pulmonary embolism and acute MI can precipitate cardiac arrest; LUCAS or manual CPR facilitates some thrombus dissolution

Advanced Airway Management

Airway management in cardiac arrest is a balancing act. Current Resuscitation Council UK guidance de-emphasises early intubation in favour of supraglottic airway devices (SGAs) such as the i-gel, particularly where intubation would cause prolonged interruptions to CPR. The i-gel is now widely used by UK paramedics as a first-line advanced airway in cardiac arrest due to its ease of insertion and acceptable seal pressures.

Once an advanced airway is in place, ventilate at 10 breaths per minute with continuous, uninterrupted chest compressions. Waveform capnography should be attached as soon as possible — an ETCO2 reading of <10 mmHg despite good CPR suggests poor cardiac output or incorrect airway placement, while a sudden rise in ETCO2 is often the first indicator of return of spontaneous circulation (ROSC).

Drug Therapy in Cardiac Arrest

Intravenous or intraosseous access should be established without interrupting CPR. JRCALC-aligned drug therapy includes:

• Adrenaline (Epinephrine) 1mg IV/IO: Given every 3–5 minutes. In VF/pVT, administer after the third shock. In PEA/asystole, give as soon as access is available.
• Amiodarone 300mg IV/IO: Given after the third shock in refractory VF/pVT. A further 150mg dose may be given after the fifth shock.

While adrenaline increases the likelihood of ROSC, evidence from the PARAMEDIC2 trial suggests it does not significantly improve neurologically intact survival. This context is important for paramedic students to understand when critically evaluating evidence.

Return of Spontaneous Circulation (ROSC)

Signs of ROSC include a sudden rise in ETCO2, visible pulse on the waveform monitor, and spontaneous movements. Once ROSC is achieved, your priorities shift to post-resuscitation care:

• Maintain SpO2 94–98% — avoid hyperoxia
• Target systolic BP >100 mmHg
• Obtain a 12-lead ECG to identify STEMI requiring emergent catheterisation
• Avoid hyperthermia; targeted temperature management may be initiated in-hospital
• Provide a clear and concise ATMIST/SBAR handover to the receiving team

When to Terminate Resuscitation

Decisions to terminate resuscitation pre-hospital are guided by JRCALC criteria and local clinical guidelines. Factors such as unwitnessed arrest with prolonged downtime, asystole throughout, absence of reversible causes, and valid Do Not Attempt Resuscitation (DNAR) documentation are all considered. These are challenging decisions that require clinical judgement, compassion, and effective communication with bystanders and family members.