Letter to the Editor

The longest persisting ventricular fibrillation with an excellent outcome – 6 h 45 min cardiac arrest

The International Commission for Mountain Emergency Medicine (ICAR MedCom) developed updated recommendations for the management of avalanche victims.

ICAR MedCom created Population Intervention Comparator Outcome (PICO) questions and conducted a scoping review of the literature. We evaluated and graded the evidence using the American College of Chest Physicians system.

We included 120 studies including original data in the qualitative synthesis. There were 45 retrospective studies (38%), 44 case reports or case series (37%), and 18 prospective studies on volunteers (15%). The main cause of death from avalanche burial was asphyxia (range of all studies 65–100%). Trauma was the second most common cause of death (5–29%). Hypothermia accounted for few deaths (0–4%).

For a victim with a burial time ≤ 60 minutes without signs of life, presume asphyxia and provide rescue breaths as soon as possible, regardless of airway patency. For a victim with a burial time > 60 minutes, no signs of life but a patent airway or airway with unknown patency, presume that a primary hypothermic CA has occurred and initiate cardiopulmonary resuscitation (CPR) unless temperature can be measured to rule out hypothermic cardiac arrest. For a victim buried > 60 minutes without signs of life and with an obstructed airway, if core temperature cannot be measured, rescuers can presume asphyxia-induced CA, and should not initiate CPR. If core temperature can be measured, for a victim without signs of life, with a patent airway, and with a core temperature < 30 °C attempt resuscitation, regardless of burial duration.

Several pathophysiologic changes occur due to severe accidental hypothermia (HT) in the cardiovascular system leading to decreased cardiac output, dysrhythmias, cold diuresis, decreased responsiveness of central nervous system, and noncardiogenic pulmonary edema. Cardiac arrest is frequent in severe HT. Extracorporeal life support (ECLS)-assisted cardiopulmonary resuscitation (CPR) can improve survival in every selected patient experiencing cardiac arrest (CA). ECLS is increasingly used with favorable results as organ support and rewarming tool in patients suffering CA in context of accidental HT. In this chapter, we aim to provide an overview of accidental HT pathophysiology and related CA providing guidance on patient selection, neurological prognostication, and treatment, including ECLS. Although the use of ECLS in patients suffering CA from accidental HT is far less frequent than CA from other causes, more patients are likely to benefit from ECLS as access to ECLS improves. A systemic approach to extracorporeal CPR that also includes clear guidance for use of ECLS in context of accidental HT is needed.

La presente revisión narrativa se centra en el diagnóstico, el tratamiento y la gestión de la hipotermia accidental. Si bien todos estos procesos son continuos, en el presente manuscrito las recomendaciones se organizan con fines descriptivos en prehospitalarias y hospitalarias.

En el ámbito prehospitalario se recomienda: a) reanimación de alta calidad de toda víctima en parada cardiaca, independientemente de la temperatura corporal; b) instaurar medidas para detener la pérdida de calor; c) iniciar el recalentamiento; d) prevenir el colapso del rescate y el efecto de recaída (afterdrop) y e) elegir adecuadamente el hospital de referencia de acuerdo con la situación clínica y hemodinámica de la víctima.

El soporte vital extracorpóreo ha revolucionado, con tasas de supervivencia que han llegado al 100%, el recalentamiento de víctimas con inestabilidad hemodinámica o paro cardiaco.

Las nuevas evidencias indican que la gestión de la hipotermia accidental ha evolucionado y ha conseguido mejorar sustancialmente el pronóstico final.

A narrative review is presented on the diagnosis, treatment and management of accidental hypothermia. Although all these processes form a continuum, for descriptive purposes in this manuscript the recommendations are organized into the prehospital and in-hospital settings.

At prehospital level, it is advised to: a) perform high-quality cardiopulmonary resuscitation for cardiac arrest patients, regardless of body temperature; b) establish measures to minimize further cooling; c) initiate rewarming; d) prevent rescue collapse and continued cooling (afterdrop); and (e) select the appropriate hospital based on the clinical and hemodynamic situation of the patient.

Extracorporeal life support has revolutionized rewarming of the hemodynamically unstable victim or patients suffering cardiac arrest, with survival rates of up to 100%.

The new evidences indicate that the management of accidental hypothermia has evolved favorably, with substantial improvement of the final outcomes.

The LINC trial evaluated two ALS-CPR algorithms for OHCA patients, consisting of 3 min' mechanical chest compression (LUCAS) cycles with defibrillation attempt through compressions vs. 2 min' manual compressions with compression pause for defibrillation. The PARAMEDIC trial, using 2 min' algorithm found worse outcome for patients with initial VF/VT in the LUCAS group and they received more adrenalin compared to the manual group. We wanted to evaluate if these algorithms had any outcome effect for patients still in VF/VT after the initial defibrillation and how adrenalin timing impacted it.

Both groups received manual chest compressions first. Based on non-electronic CPR process documentation, outcome, neurologic status and its relation to CPR duration prior to the first detected return of spontaneous circulation (ROSC), time to defibrillation and adrenalin given were analysed in the subgroup of VF/VT patients.

Seven hundred and fifty-seven patients had still VF/VT after initial chest compressions combined with a defibrillation attempt (374 received mechanical CPR) or not (383 received manual CPR). No differences were found for ROSC (mechanical CPR 58.3% vs. manual CPR 58.6%, p = 0.94), or 6-month survival with good neurologic outcome (mechanical CPR 25.1% vs. manual CPR 23.0%, p = 0.50). A significant difference was found regarding the time from start of manual chest compression to the first defibrillation (mechanical CPR: 4 (2–5) min vs manual CPR 3 (2–4) min, P < 0.001). The time from the start of manual chest compressions to ROSC was longer in the mechanical CPR group.

No difference in short- or long-term outcomes was found between the 2 algorithms for patients still in VF/VT after the initial defibrillation. The time to the 1st defibrillation and the interval between defibrillations were longer in the mechanical CPR group without impacting the overall outcome. The number of defibrillations required to achieve ROSC or adrenalin doses did not differ between the groups.