Cardiac Arrest Management for Paramedics

Cardiac Arrest Management for UK Paramedics

Cardiac arrest remains one of the most time-critical emergencies a paramedic will face in pre-hospital practice. With approximately 30,000 out-of-hospital cardiac arrests (OHCAs) occurring in the UK each year, the ability to deliver a slick, well-coordinated resuscitation response is a core clinical competency. This article walks through the key principles of cardiac arrest management in line with current UK Resuscitation Council and JRCALC guidelines — from initial scene assessment through to post-ROSC care.

Scene Safety and Initial Assessment

Before approaching any cardiac arrest patient, ensure scene safety. Consider hazards such as moving traffic, electrical risks, or potential violence. Once safe, confirm the patient is unresponsive and not breathing normally — agonal gasps should be treated as cardiac arrest. Shout for help and begin your resuscitation sequence immediately.

As the paramedic crew arrives, rapidly assign roles. One clinician leads compressions and airway management, while the other operates the defibrillator, gains IV or IO access, and prepares medications. Clear role allocation reduces cognitive load and improves the efficiency of the overall resuscitation effort.

High-Quality CPR: The Foundation of Resuscitation

High-quality CPR is the single most important intervention in cardiac arrest. No drug or advanced airway will compensate for poor compressions. Follow these key parameters:

• Rate: 100–120 compressions per minute
• Depth: 5–6 cm in adults
• Recoil: Allow full chest recoil between compressions
• Ratio: 30:2 until an advanced airway is placed, then continuous compressions with asynchronous ventilation at 10 breaths/minute
• Interruptions: Minimise all pauses — keep peri-shock pauses to under 5 seconds

Rescuer fatigue significantly degrades compression quality within 2 minutes. Rotate the compressor role every 2 minutes, ideally timed with rhythm checks to avoid additional pauses.

Rhythm Recognition and Defibrillation

As soon as the defibrillator is attached, identify the underlying rhythm. Cardiac arrest rhythms fall into two categories:

Shockable Rhythms

• Ventricular Fibrillation (VF): Chaotic, disorganised electrical activity with no coordinated contraction
• Pulseless Ventricular Tachycardia (pVT): A regular, fast, broad-complex rhythm with no cardiac output

For shockable rhythms, deliver a single shock as rapidly as possible, then immediately resume CPR for 2 minutes before the next rhythm check. For biphasic defibrillators — standard in UK pre-hospital practice — use the manufacturer-recommended energy level, typically 150–200 J for the first shock, then 150–360 J for subsequent shocks.

Non-Shockable Rhythms

• Pulseless Electrical Activity (PEA): Organised electrical activity without a palpable pulse
• Asystole: Absence of electrical activity, or P-wave only asystole

Non-shockable rhythms require a focus on CPR quality and identifying reversible causes — the 4 Hs and 4 Ts.

The 4 Hs and 4 Ts: Reversible Causes

A structured approach to reversible causes should run in parallel with resuscitation efforts. This is particularly critical in PEA, where an underlying treatable cause is likely:

• Hypoxia — Ensure airway patency and adequate ventilation
• Hypovolaemia — Consider in trauma, GI bleed, or anaphylaxis; treat with IV fluids
• Hypo/Hyperkalaemia and metabolic disorders — Review history, consider calcium chloride in suspected hyperkalaemia
• Hypothermia — Core temperature below 30°C warrants prolonged resuscitation; "not dead until warm and dead"
• Tension Pneumothorax — Decompress with needle thoracocentesis or finger thoracostomy
• Tamponade — Consider in penetrating trauma; requires hospital-level intervention
• Toxins — Review history for overdose; consider naloxone for opioid toxicity
• Thrombosis — Pulmonary embolism or acute MI; consider thrombolysis if PE is suspected

Airway Management in Cardiac Arrest

Airway management should not interrupt CPR. Begin with basic airway adjuncts — OPA or NPA — alongside bag-valve-mask ventilation. Once skilled personnel are available, supraglottic airway devices (SGAs) such as the i-gel are recommended as the first-line advanced airway in UK pre-hospital cardiac arrest, in line with JRCALC guidance. Tracheal intubation remains an option for appropriately trained and credentialed paramedics but should not cause significant interruption to chest compressions.

Once an advanced airway is in place, use waveform capnography (EtCO2) to confirm placement and monitor CPR quality. An EtCO2 reading above 10 mmHg suggests effective compressions. A sudden rise in EtCO2 may indicate return of spontaneous circulation (ROSC) and should prompt a rhythm and pulse check.

Medications in Cardiac Arrest

Drug therapy plays a supportive role in resuscitation. Current JRCALC guidance for adult cardiac arrest includes:

• Adrenaline 1 mg IV/IO: Given every 3–5 minutes. In non-shockable rhythms, administer as soon as access is gained. In VF/pVT, give after the third shock.
• Amiodarone 300 mg IV/IO: Given after the third shock in refractory VF/pVT. A further 150 mg dose can be given after the fifth shock.

Obtain IV or IO access early, but do not compromise CPR quality to do so. The intraosseous route is reliable and effective when IV access is difficult — common sites include the proximal tibia, proximal humerus, and sternal manubrium.

Return of Spontaneous Circulation (ROSC) and Post-Resuscitation Care

ROSC is confirmed by a palpable central pulse, a sustained rise in EtCO2, or spontaneous movement. Immediately following ROSC:

• Obtain a 12-lead ECG — identify and act on ST-elevation MI (STEMI) for direct cath lab activation
• Target SpO2 94–98% and avoid hyperoxia
• Target EtCO2 35–45 mmHg to avoid hypocapnia
• Manage hypotension with fluid and vasopressors if available
• Aim for normoglycaemia
• Provide a structured pre-alert to the receiving hospital using ATMIST or SBAR

Pre-alert the receiving emergency department early to ensure the appropriate team is ready — this is a critical step in the overall chain of survival that is too often underemphasised in clinical training.

When to Cease Resuscitation

The decision to terminate resuscitation efforts is one of the most challenging in pre-hospital care. JRCALC and local trust protocols provide criteria to guide this decision, including duration of resuscitation, presenting rhythm, and clinical context. Clear documentation and sensitive communication with bystanders and family members are essential professional responsibilities.