Advanced Life Support (Adult)

Operational Considerations. In the military context, cardiac arrest management must maintain operational credibility. Clear leadership, disciplined communication, visible escalation of appropriate care, and structured debriefing are essential to preserve trust, cohesion, and mission effectiveness. Clinicians should consider the impact of their care on the wider operation.

Advanced Life Support (ALS) is fundamentally an attempt to maintain cerebral and coronary perfusion long enough for defibrillation and correction of reversible causes to succeed. Decades of resuscitation science demonstrate that survival from cardiac arrest is driven primarily by the quality and continuity of chest compressions and timely defibrillation, with drugs and advanced technologies offering incremental benefit at best. This evidence base applies directly to military practice, but its operational implications are magnified when evacuation timelines are prolonged, critical care capability is constrained, and medical events unfold within high-risk environments.

At the centre of modern ALS is not only compression rate and depth, but the proportion of the arrest during which effective chest compressions are delivered. During cardiac arrest, blood flow exists only while the chest is being compressed. Each pause results in a rapid fall in coronary and cerebral perfusion pressure, and several compressions are required to rebuild that pressure. For this reason, the proportion of total arrest time spent actively delivering compressions is strongly associated with return of spontaneous circulation and survival, particularly in shockable rhythms. 

In operational environments, whether maritime platforms, forward medical facilities, austere airfields, or during aeromedical evacuation, interruptions are more likely due to confined spaces, personal protective equipment, environmental hazards, platform movement, or limited personnel. The physiological cost of those interruptions is unchanged, but the margin for recovery may be smaller if definitive post-resuscitation care is delayed. Maintaining a high proportion of time delivering effective chest compressions therefore becomes even more critical in military settings.

Early defibrillation for ventricular fibrillation or pulseless ventricular tachycardia remains the most powerful intervention in ALS. Its effectiveness is closely linked to preceding CPR and minimisation of pauses around shock delivery. Modern evidence emphasises that defibrillation success depends less on technological escalation and more on disciplined execution: charging during ongoing compressions, limiting rhythm check pauses, and immediately resuming compressions after shock delivery. Operationally, this reinforces the importance of equipment accessibility, team rehearsal in constrained environments, and leadership that protects compression continuity.

The role of vasopressors, particularly adrenaline, is defined by large contemporary randomised evidence demonstrating increased return of spontaneous circulation and improved survival to 30 days, but no proportional increase in favourable neurological outcome. This distinction is clinically and operationally significant. Adrenaline improves the likelihood of survival, but not necessarily survival without severe neurological impairment. In deployed settings, where prolonged evacuation or limited intensive care capacity may increase the risk of survival with significant neurological disability, understanding what adrenaline does—and does not—achieve is essential. It remains part of ALS algorithms because it increases survival, but its effect size is modest and must be interpreted realistically.

Similarly, anti-arrhythmic drugs for shock-refractory ventricular fibrillation have not been shown to significantly improve survival to discharge or favourable neurological outcome compared with placebo in large trials. More recent evidence suggests that altering defibrillation strategy in refractory ventricular fibrillation, such as changing shock vectors or using Double Sequential External Defibrillation (DSED) may improve survival in selected systems. However, DSED is not recommended within the 2025 Resuscitation Council (UK) guidelines outside of research. Consultation with the council suggests this is due to limited evidence (early observational studies and a single well-conducted study, the 2022 DOSE-VF trial, having a smaller sample size than planned due to it being halted as a result of the COVID-19 pandemic) and the unknown impact on defibrillators being operating outside of their design. Both vector change and DSED should only be utilised in a well rehearsed team. Where feasible, in well-equipped military medical facility with experienced clinicians, these strategies may be considered, but their benefit depends entirely on preserving compression continuity and avoiding excessive pauses.

Airway management evidence further reinforces the primacy of uninterrupted CPR. Large pragmatic trials comparing supraglottic airway strategies with tracheal intubation have shown no meaningful difference in functional neurological outcomes. In operational contexts—where intubation may be complicated by darkness, noise, reduced manpower, or protective equipment—this evidence supports selecting the airway technique that can be delivered rapidly and reliably without degrading the proportion of time compressions are provided. The most technically advanced airway is of little value if it compromises perfusion by increasing interruptions.

Mechanical chest compression devices have similarly not demonstrated survival advantage when used routinely compared with high-quality manual CPR. Their value in military practice lies in specific logistical circumstances—such as prolonged transport, aeromedical evacuation, or situations with limited personnel—rather than intrinsic superiority. Again, their benefit depends on deployment without prolonged interruption.

Post-resuscitation care has evolved substantially. Large, randomised trials have demonstrated no benefit of routine therapeutic hypothermia compared with controlled normothermia and active fever prevention. The contemporary evidence base supports avoidance of hyperthermia and optimisation of oxygenation, ventilation, haemodynamics, and metabolic parameters as the cornerstone of post-ROSC management. In deployed environments, this is operationally relevant: maintaining normothermia and physiological stability is both evidence-based and achievable, whereas complex cooling protocols may not be.

Whilst Extracorporeal Cardiopulmonary Resuscitation (ECMO) is a useful tool within civilian practice, indicated for patients with witnessed, refractory cardiac arrest, typically with a shockable rhythm and a clear reversible cause, it is generally impractical to deliver on operations. However, it may be considered when operating within countries with a developed ECMO system. 

It is recognised that traumatic cardiac arrest follows a distinct pathophysiological and doctrinal framework and is addressed separately within military guidelines. The ALS evidence discussed here therefore primarily informs management of non-traumatic cardiac arrest on operations, including arrhythmic, hypoxic, immersion-related, or other medical causes.

Beyond its physiological and technical dimensions, cardiac arrest on military operations has a profound impact on the wider team and the collective moral contract between personnel and the medical system that supports them. Sailors, soldiers and aviators must have confidence that if one of their own collapses, every appropriate, evidence-based intervention will be delivered with urgency, competence, and commitment. This belief is fundamental to trust in medical support and to the willingness of individuals to continue operating in high-risk environments.

In this context, the credibility of Advanced Life Support is not derived from indiscriminate escalation, but from clearly recognisable, professional, and determined care that aligns with best available evidence. A well-led resuscitation—characterised by prompt initiation of high-quality CPR, early defibrillation where indicated, timely administration of appropriate drugs, and disciplined team coordination—demonstrates unequivocally that the medical team is doing everything that can reasonably influence outcome. Even when resuscitation is unsuccessful, the visible delivery of ALS to a high standard reassures the wider team that their colleague received full and serious medical care.

Importantly, this reassurance is grounded in evidence-based practice rather than futile or theatrical intervention. Personnel are more likely to retain confidence in medical care when interventions are purposeful, timely, and coherent. The ALS evidence base makes clear that survival is driven primarily by maintaining perfusion—reflected in the proportion of arrest time during which effective chest compressions are delivered—and by timely defibrillation where indicated. Delivering these elements well communicates commitment and competence more convincingly than prolonged escalation that degrades care quality.

Leadership and communication are therefore integral components of ALS on operations. Clear command during the resuscitation, visible coordination of tasks, and calm explanation to non-medical leaders about what is being done reinforce trust. When resuscitation efforts conclude, a clear articulation that all appropriate evidence-based measures were delivered helps the wider team process the outcome and maintain confidence in medical support. This supports operational continuity by reducing uncertainty, moral injury, and loss of trust that could otherwise impair team function.

Taken together, the evidence base for ALS delivers a consistent message across civilian and military contexts. Survival depends predominantly on maintaining perfusion and delivering timely defibrillation, while drugs and advanced interventions offer incremental benefit only when they preserve these fundamentals. In operational environments, where constraints are greater and post-resuscitation care may be delayed, disciplined execution of these core principles is even more critical. Doing everything that is known to work—and doing it well—protects both the individual casualty and the collective effectiveness of the force.

Hypoxia is a very common cause of cardiac arrest with causes including trauma (see Traumatic Cardiac Arrest guidelines), airway obstruction, sedation, drowning, blast or smoke inhalation. Look for history of cyanosis, poor chest rise, difficult ventilation, facial, neck or chest trauma or deteriorating oxygen saturations prior to cardiac arrest.

Apply maximum level of oxygen available (e.g. 15 litres)

Ensure adequate airway management with airway manoeuvres, adjuncts.

Use a two-person technique for bag-valve mask ventilation to ensure a good seal. 

Insert iGel once CPR in progress, with end-tidal CO2 when available. 

Check for bilateral chest rise and exclude tension pneumothorax early, if found, manage as per traumatic cardiac arrest. 

In deployed hospital facilities, progression to a definitive airway is usually appropriate once skilled personnel and equipment are available, particularly where arrest is prolonged, aspiration risk is high, or controlled ventilation is required.

A cuffed endotracheal tube is generally preferred over a supraglottic airway in this setting. Endotracheal intubation provides a sealed airway with improved protection against aspiration, more reliable delivery of ventilation and airway pressures, and more consistent waveform capnography to confirm tracheal placement, monitor CPR quality, and detect ROSC. These advantages become increasingly important during prolonged resuscitation, patient movement, or delayed evacuation.

Supraglottic airways, including the i-gel, remain appropriate as an initial or bridging airway, particularly if immediate intubation would cause a prolonged interruption to chest compressions or the skillset/monitoring for ETT is not present. In line with Resuscitation Council (UK) (RCUK) guidance, airway interventions must not compromise compression quality, and intubation should only proceed when it can be achieved with minimal interruption. 

Airway management should also include exclusion of obstruction or displacement, suctioning of regurgitated material, and assessment for reversible pulmonary pathology. 

Where bronchospasm or refractory hypoxia persists, escalation to salbutamol (3–20 micrograms/min IV with caution to regularly check potassium), ketamine (0.5–2 mg/kg/hour IV) or adrenaline (0.05–0.5 micrograms/kg/min IV replacing bolus doses) infusions may be required.

In non-traumatic cardiac arrest, hypovolaemia most commonly reflects distributive or relative hypovolaemia, such as sepsis or anaphylaxis, rather than haemorrhage. Management should therefore prioritise early circulatory support alongside treatment of the underlying cause.

Commence fluid resuscitation with appropriate fluid (blood products if available for trauma). 

Consider trauma history (assess for massive external bleeding, flat neck veins particularly in a non-shockable rhythm). Consider neurogenic shock if prior to cardiac arrest history of high-cervical/thoracic spinal injury, history of hypotension with inappropriate bradycardia with warm, dry skin. Manage as per traumatic cardiac arrest with additional use of adrenaline if neurogenic shock suspected.. 

Consider history of allergen exposure, especially with bronchospasm / difficult ventilation / presence of urticarial rash, remove any potential allergen (medication, stings etc.) and ensure adrenaline as per standard cardiac arrest treatment. Care should not focus on antihistamine and steroids are not first line treatment of anaphylaxis.

Consider history or signs of infection such as fever or hypothermia, particularly in a non-shockable rhythm. Give broad spectrum antibiotics if easily available. 

Septic cardiac arrest requires early vasopressor support, prompt antimicrobial therapy, and source control where feasible. 

Anaphylaxis requires immediate adrenaline administration, supported by oxygen, intravenous fluids, and adjunctive therapies in line with national guidance.

Where haemorrhage is suspected, management should follow the traumatic cardiac arrest pathway rather than this guideline.

Whilst renal failure is unlikely in Service Personnel, dehydration / rhabdomyolysis due to environmental or physical workload, crush injuries or extensive burns do occur. Living in close proximity to others means GI infections can spread and cause electrolyte loss through diarrhoea and vomiting. Massive transfusion can also raise the patient’s potassium load. 

Check BM and treat any low glucose levels. 

Check pre-arrest ECGs/peri-arrest rhythms on rhythm checks for wide QRS, peaked t-waves, sine wave pattern, or history of progressive bradycardia (hyperkalaemia), flattened t-waves, prominent u-waves, ST depression, prolonged QTc, ventricular irritability (ectopics), atrial tachyarrythmias, polymorphic VT or VF (hypokalaemia). 

If hyperkalaemia suspected, give 10ml 10% calcium chloride to stabilise the myocardium. 

Hyperkalaemia should be treated with immediate intravenous calcium (Calcium gluconate 10% 30 mL peripheral IV or Calcium chloride 10% 10 mL central IV/IO) for membrane stabilisation, followed by intracellular potassium shift using insulin with dextrose (10 units Actrapid with either 50ml of 50% or 125ml of 20% dextrose), sodium bicarbonate, and nebulised beta-agonists. Whilst sodium bicarbonate can also promote a small intracellular shift of potassium by correcting metabolic acidaemia, it should be highlighted that this effect is unreliable and clinically modest so should not be used as first line management. 

Hypokalaemia should be corrected cautiously with intravenous potassium (maximum 20 mmol over 10 minutes) with magnesium replacement (5-10 mmol over 10 minutes) where indicated. 

Adrenaline, which is being given as part of immediate management, may shift potassium from the blood into the cells which will support reduction in hyperkalaemia, but conversely contribute to hypokalaemia. 

Urgent transfer to a facility capable of measuring potassium, with consideration of use of insulin/dextrose  for hyperkalaemia, or magnesium and potassium replacement for hypokalaemia if available on route, on advice of a senior clinician if there is a high index of suspicion. 

Other metabolic causes must not be overlooked. Hypoglycaemia requires prompt intravenous dextrose, while hypocalcaemia—particularly following large-volume blood transfusion—should be corrected with calcium replacement. 

Hypothermia or Hyperthermia are more likely than in civilian practice due to the risks of immersion, exposure to high and low temperatures and workload of military personnel. 

Remove wet clothes (do not just open). 

If the patient feels warm or cool to the touch, ensure measurement of core body temperature (using a rectal thermometer if available). 

If core body temperature greater than 40⁰C, actively cool using ice backs to axillae and groin, cooled fluids, water spraying and fanning. Whole-body cold water immersion is not practical during cardiac arrest.

Hypothermia should be actively excluded and managed, and patients should not be declared dead until rewarmed unless injuries are clearly incompatible with life. Core temperature should be measured using a rectal probe, and active rewarming initiated using forced-air warming and warmed intravenous fluids (or blood products if otherwise indicated), alongside ongoing high-quality CPR.

Defibrillation should not be withheld. However, if the core temperature is below 30 °C, no more than three defibrillation attempts should be delivered, with further shocks deferred until rewarming above 30 °C.

Resuscitation drug administration must be modified in hypothermia, in line with RCUK 2025 guidance. When the core temperature is below 30 °C, adrenaline and other resuscitation drugs should be withheld, as drug metabolism is markedly reduced and accumulation may occur. When the core temperature is between 30 °C and 35 °C, resuscitation drugs may be given but at doubled intervals; for example, adrenaline should be administered every 6–10 minutes rather than every 3–5 minutes. Once the core temperature exceeds 35 °C, standard drug dosing and intervals should be resumed.

Hypothermia should be anticipated in maritime, aviation, cold-weather, or prolonged exposure operations and managed in parallel with ALS.

Although more commonly associated with trauma, tension pneumothorax remains a recognised reversible cause of arrest in medical patients, particularly during positive-pressure ventilation or in severe underlying lung disease.

Other signs are high pressures required to ventilate the patient, reduced breath sounds unilaterally (although bilateral pneumothorax is possible), resonant percussion note on the affected side and a deviated trachea (late sign). 

Ensure minimum interruptions to CPR if suspected. 

Perform a needle decompression, thoracostomy or chest drain as team skill set allows on the affected side. 

Where suspected, treatment should not be delayed for imaging. Immediate decompression should be performed, followed by definitive chest drainage once ROSC or physiological stability is achieved.

Cardiac tamponade should be considered in unexplained pulseless electrical activity or refractory shock. Point-of-care ultrasound may be used during ALS where it does not interrupt chest compressions. Pericardiocentesis may be undertaken as a temporising measure or thoracotomy dependent on local capability and the underlying cause. Follow the Traumatic Cardiac Arrest CGO for suspected tamponade in trauma

Toxicological causes should be actively considered in non-traumatic cardiac arrest. Management is antidote-driven and should proceed in parallel with standard ALS. This includes naloxone for opioid toxicity, sodium bicarbonate for sodium-channel blockade, calcium for calcium-channel blocker toxicity, and lipid emulsion therapy in selected refractory cases. Early airway control and ventilation are frequently required. 

Always reconsider your own safety if a toxic cause is considered. 

Give antidote if immediately available such as Naloxone for suspected opioid overdose.

See toxicology CGOs or utilise other available resources to gather further information, for example TOXBASE, particularly unknown poisoning guidance https://www.toxbase.org/4a24ca/globalassets/upload/toxidromes-july-v-2-2024.pdf

Thrombosis encompasses a blood clot or multiple clots causing a coronary vessel occlusion (Myocardial Infarction) or pulmonary embolism. Consider this as a reversible cause, particularly with a sudden unexplained collapse, recent dehydrating activity or environment, patient history suggestive of risk factors or previous clot or if there is evidence of Deep Vein Thrombosis (DVT).  Typically, coronary thrombus is more likely to cause a shockable rhythm compared to pulmonary embolism for which pulseless electrical activity (PEA), a non-shockable rhythm, is more likely. Thrombolysis is only shown to improve outcome to discharge in PE. 

Focus remains on good quality chest compressions and early defibrillation when indicated for both PE and coronary thrombus.  

If PE is suspected, transfer to a facility capable to delivering thrombolysis if the operational context allows.

Coronary Thrombosis. Acute coronary occlusion remains a leading cause of non-traumatic cardiac arrest. Early defibrillation is central where a shockable rhythm is present, with amiodarone used for refractory ventricular arrhythmias. Following ROSC, prompt ECG assessment is required. Where PCI is unavailable, thrombolysis may be considered if suspicion is high and bleeding risk acceptable. Selected Role 3 facilities may consider extracorporeal CPR in line with local governance.

Pulmonary Thrombosis. Massive pulmonary embolism should be suspected in PEA arrest with relevant risk factors. Thrombolysis during cardiac arrest is appropriate where PE is strongly suspected, recognising that prolonged CPR, often 60–90 minutes, may be required following lysis. Give 50mg bolus Alteplase over 1 to 2 minutes and consider a further 50mg after 15 minutes. Alterplase should be mixed with water for injection of 0.9% sodium chloride, but NOT dextrose as it precipitates. In true cardiac arrest, absolute contraindications are relative, but caution is required if the patient has recent major surgery, intracranial pathology, active bleeding or has a trauma mechanism. 

In a military operational environment, care after Return of Spontaneous Circulation (ROSC) should prioritise prevention of secondary injury while accounting for resource constraints, evacuation timelines, and the tactical situation. A structured ABCDE reassessment should be undertaken, led by the most suitable senior clinician available, with early consideration of evacuation to a higher echelon of care. Clear documentation and early reach-back to critical care or cardiology support should occur where available, particularly if PCI or advanced organ support may be required.

Airway, breathing and circulation should be optimised pragmatically, with tracheal intubation if not already performed during the cardiac arrest for comatose patients  or with the use of sedative medication for those requiring controlled ventilation. Oxygenation should target normal oxygen saturations (i.e. SpO₂ 94–98%), but in oxygen-limited environments the lower end of this range may be acceptable to preserve supply. Ventilation should aim for normocapnia, guided by waveform capnography and formal blood gasses where available. Circulatory management should target a Mean Arterial Pressure (MAP) ≥65 mmHg (individualised where appropriate), using cautious fluids and vasopressors such as noradrenaline when required. A 12-lead ECG should be performed early, and suspected STEMI should trigger urgent evacuation planning or specialist discussion.

Neuroprotection should focus on avoidance of fever, maintenance of physiological stability, and prevention of secondary brain injury. Active temperature monitoring should be instituted; in austere settings this may rely on simple environmental control and antipyretics rather than formal targeted temperature devices. Glucose should be maintained in a pragmatic normoglycaemic range (approximately 7–10 mmol/L) using point-of-care testing. Sedation should be titrated to prevent agitation or shivering where temperature control is attempted. Clinicians should remain vigilant for seizures and treat clinically apparent events promptly, recognising that EEG monitoring is unlikely to be available forward.

A continued search for reversible causes should occur even after ROSC, with particular attention in military contexts to tension pneumothorax, tamponade, toxin or CBRN exposure, electrolyte disturbance, and pulmonary embolism. Point-of-care ultrasound, if available, should support haemodynamic assessment if a suitably competent user is available. If the patient had a shockable rhythm, consider giving 900mg amiodarone infusion of 24 hours. 

Post-event debriefing should occur when operationally possible to support team learning and psychological wellbeing, maintaining confidence that proportionate, evidence-based care was delivered.

Resuscitation can be discontinued when:

• The patient shows clear signs of life i.e. Return of Spontaneous Circulation (ROSC).
• You are directed to cease resuscitation by a senior clinician, following discussion of all of the circumstances of the case, with no realistic reversible cause identified.
• You are unable to gain advice by any means of a senior clinician, the patient has had high quality ALS (i.e. effective CPR, all reversible causes have been actively sought and treated, there has been no ROSC at any point, there are no physiological signs of improvement such as improving end-tidal CO2 and the patient has a minimum of 45 minutes of persistent non-shockable rhythm and the team unanimously agree that continuing is not in the patient’s best interests. See Cessation of Cardiac Arrest Management CGO for further details.
• It becomes unsafe for you to continue. This includes of an evolving situation (for example the spread of fire onboard a ship, nearby kinetic action, concern for an CBRN hazard or severe air turbulence).
• You become too exhausted to continue (for example as a lone provider, without other personnel who can provide chest compressions).