Cardiac Arrest Management for Paramedics UK

Cardiac Arrest Management for Paramedics: A UK Pre-Hospital Guide

Cardiac arrest is one of the most time-critical emergencies a paramedic will face. In the UK, approximately 30,000 out-of-hospital cardiac arrests (OHCAs) are attended by ambulance services each year. Survival rates remain stubbornly low, but the evidence is clear: high-quality, protocol-driven pre-hospital care significantly improves outcomes. This guide is designed to help UK student paramedics understand the core principles of cardiac arrest management in line with JRCALC guidelines and NHS practice.

The Chain of Survival

Effective cardiac arrest management begins long before the ambulance arrives. The Resuscitation Council UK promotes the Chain of Survival as a framework for understanding where interventions can improve survival:

1. Early recognition and call for help
2. Early bystander CPR
3. Early defibrillation
4. Post-resuscitation care

As a paramedic, you typically enter the chain at step three or four. Your role is to build on whatever has already been done and deliver advanced life support (ALS) without unnecessary interruption to chest compressions.

Initial Scene Assessment and Safety

Before approaching any patient, ensure scene safety. In cardiac arrest scenarios, this includes dynamic risk assessment for hazards such as traffic, structural collapse, or infectious material. A rapid primary survey will confirm unresponsiveness, absence of normal breathing, and absence of a central pulse — all three must be present to confirm cardiac arrest and begin resuscitation.

If bystander CPR is in progress, briefly assess quality and take over if compressions are inadequate. Every second of high-quality CPR matters.

High-Quality CPR: The Foundation of Resuscitation

No drug or advanced intervention compensates for poor CPR. The Resuscitation Council UK and JRCALC guidelines emphasise the following standards:

• Rate: 100–120 compressions per minute
• Depth: 5–6 cm in adults
• Recoil: Allow full chest recoil between compressions
• Interruptions: Minimise pauses — aim for a chest compression fraction (CCF) above 60%
• Ratio: 30:2 until an advanced airway is secured, then continuous compressions at 100–120/min with ventilations at 10/min

Team dynamics are crucial. Rotate the compressor every two minutes to prevent fatigue-related deterioration in quality.

Airway Management in Cardiac Arrest

Airway management strategy should be proportionate to team skill and experience. Options available to UK paramedics include:

• Bag-valve-mask (BVM) with oropharyngeal airway (OPA) — appropriate initial approach
• Supraglottic airway devices (SGAs) such as the i-gel — widely used in UK pre-hospital practice as a first-line advanced airway
• Tracheal intubation — only where the paramedic is trained and proficient, as evidence suggests intubation attempts can cause prolonged CPR interruptions

The AIRWAYS-2 trial, a landmark UK study, found that i-gel insertion was non-inferior to tracheal intubation in OHCA. Many UK ambulance services now recommend SGAs as the preferred advanced airway in cardiac arrest.

Rhythm Recognition and Defibrillation

Attach monitoring electrodes as early as possible. Cardiac arrest rhythms fall into two categories:

Shockable Rhythms

• Ventricular fibrillation (VF)
• Pulseless ventricular tachycardia (pVT)

For shockable rhythms, deliver a single unsynchronised shock as soon as the defibrillator is ready. In adults, biphasic defibrillators typically deliver 150–200J for the first shock and equivalent energy for subsequent shocks — follow your device manufacturer's guidance and local protocol. Resume CPR immediately after the shock without reassessing rhythm or pulse, continuing for two minutes before the next rhythm check.

Non-Shockable Rhythms

• Pulseless electrical activity (PEA)
• Asystole

For non-shockable rhythms, CPR is the primary intervention. Focus shifts to identifying and treating reversible causes.

The 4Hs and 4Ts: Reversible Causes

Identifying and correcting reversible causes is central to successful resuscitation. The 4Hs and 4Ts framework is a useful aide-memoire:

• Hypoxia — ensure effective ventilation and oxygenation
• Hypovolaemia — consider trauma, haemorrhage, or anaphylaxis; establish IV access and fluid resuscitation
• Hypo/hyperkalaemia and metabolic disorders — consider history of renal failure, diabetes
• Hypothermia — assess core temperature; do not confirm death until patient is warm
• Tension pneumothorax — needle decompression if clinically suspected
• Tamponade — cardiac, consider in penetrating trauma
• Toxins — consider overdose; naloxone for opioid toxicity, specific antidotes where indicated
• Thrombosis — pulmonary embolism or acute MI; consider thrombolysis in refractory arrest

Drug Therapy in Cardiac Arrest

According to JRCALC guidelines, the primary drug used in cardiac arrest is adrenaline (epinephrine) 1mg IV/IO. The timing differs by rhythm:

• Non-shockable rhythms: Adrenaline as soon as IV/IO access is established
• Shockable rhythms: Adrenaline after the third shock, then every 3–5 minutes (every other loop)

Amiodarone 300mg IV/IO is given after the third shock in refractory VF/pVT, with a further 150mg dose after the fifth shock if required. Establish IV or IO access early — the intraosseous route is a reliable and fast alternative when IV access is difficult.

Return of Spontaneous Circulation (ROSC)

Signs of ROSC include the return of a central pulse, a sudden rise in end-tidal CO₂ (ETCO₂), and spontaneous movement or breathing. ETCO₂ monitoring during CPR is strongly recommended — a sudden rise above 40 mmHg often indicates ROSC before a pulse can be palpated.

Post-ROSC priorities in the pre-hospital environment include:

• Targeted oxygen therapy — maintain SpO₂ 94–98%
• 12-lead ECG to identify STEMI requiring urgent PCI
• Blood glucose measurement and correction
• Avoid hypotension — target systolic BP above 100 mmHg
• Pre-alert receiving hospital with full handover

When to Terminate Resuscitation

The decision to cease resuscitation in the pre-hospital setting is clinically and ethically significant. JRCALC provides guidance on criteria that may support termination, including prolonged downtime with no bystander CPR, non-shockable rhythm throughout, and no ROSC despite optimal ALS. Always consider the patient's known wishes and any advance decisions to refuse treatment (ADRT). Document your decision clearly and communicate sensitively with bystanders and family present at scene.