Endovascular catheter as a rewarming method for accidental hypothermia

Accidental Hypothermia: 2021 Update

Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient arrests, continuous cardiopulmonary resuscitation (CPR) should be performed. In hypothermic patients, the chances of survival and good neurological outcome are higher than for normothermic patients for witnessed, unwitnessed and asystolic cardiac arrest. Mechanical CPR devices should be used for prolonged rescue, if available. In severely hypothermic patients in cardiac arrest, if continuous or mechanical CPR is not possible, intermittent CPR should be used. Rewarming can be accomplished by passive and active techniques. Most often, passive and active external techniques are used. Only in patients with refractory hypothermia or cardiac arrest are internal rewarming techniques required. ECLS rewarming should be performed with extracorporeal membrane oxygenation (ECMO). A post-resuscitation care bundle should complement treatment.

Endovascular rewarming in the emergency department for moderate to severe accidental hypothermia

BACKGROUND

Endovascular temperature control catheters can be utilized for emergent rewarming in accidental hypothermia. The purpose of this study was to compare patients with moderate to severe hypothermia rewarmed with an endovascular temperature control catheter versus usual care at our institution.

METHODS

We conducted a retrospective, observational cohort study of patients with moderate to severe accidental hypothermia (core body temperature less than 32°C) in the Emergency Department of an urban, tertiary care medical center. We identified the rewarming techniques utilized for each patient, including those who had an endovascular temperature control catheter placed (Quattro© or Icy© catheter, CoolGuard© 3000 regulation system, Zoll Medical). Rewarming rates and outcomes were compared for patients with and without the endovascular temperature control catheter. We systematically screened for procedural complications.

RESULTS

There were 106 patients identified with an initial core temperature less than or equal to 32°C; 52 (49%) patients rewarmed with an endovascular temperature control catheter. Other methods of rewarming included external forced-air rewarming (85, 80%), bladder lavage (17, 16%), gastric lavage (10, 9%), closed pleural lavage (6, 6%), and peritoneal lavage (3, 3%). Rate of rewarming did not differ between the groups with and without catheter-based rewarming (1.3°C/h versus 1.0°C/h, difference 0.3°C, 95% confidence interval [CI] of the difference 0-0.6°C) and neither did survival (70% versus 71%, difference 1%, 95% CI -17 to 20%). We did not identify any significant vascular injuries resulting from endovascular catheter use.

CONCLUSION

The endovascular temperature control system was not associated with an increased rate of rewarming in this cohort with moderate to severe hypothermia; however, this technique appears to be safe and feasible.

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.