Introduction
Severe accidental hypothermia, defined as a core body temperature<28°C, is associated with multiple neurologic, cardiac, and metabolic complications.Reference Niehaus, Pechulis, Wu, Frei, Hong, Sandhu and Greenberg 1 Mortality from hypothermia was attributed to 13,419 persons from 2003 through 2013 with an annual rate of 0.3 to 0.5 per 100,000.Reference Sawamoto, Bird and Katayama 2 The most common cause of death from severe hypothermia is cardiac arrest, resulting from slowing of conduction velocity in the myocardium and subsequent ventricular fibrillation (VF); patients who are intubated as part of resuscitative efforts often suffer fibrillatory arrest.Reference Sawamoto, Bird and Katayama 2 The myocardium quickly will recover normal, organized, electrical activity when re-warmed; consequently, aggressive warming techniques should accompany standard cardiopulmonary resuscitation (CPR) in hypothermic cardiac arrest.Reference Meiman, Anderson and Tomasallo 3 While body temperature can be raised 2-4°C using warm saline infusion, increases as high as 12°C per hour have been noted with the use of extracorporeal membrane oxygenation (ECMO).Reference Southwick and Dalglish 4 This report presents three cases of severe accidental hypothermia who were treated with ECMO; by network policy, this series was waived review by the Lehigh Valley Hospital (Allentown, Pennsylvania USA) IRB.
Report
Case 1
A 25-year-old intoxicated female was brought to the emergency department (ED) having been found on New Year’s Day in a wooded area with a core body temperature of 26°C and a Glasgow Coma Scale (GCS) score of 7. The patient arrived via Emergency Medical Services (EMS) in normal sinus rhythm; however, at the time of intubation, deteriorated to a VF cardiac arrest which persisted despite chest compressions, 6 mg epinephrine, three ampules of calcium gluconate, 150 mg of amiodarone, and four attempts at defibrillation. In addition, the patient underwent standard re-warming therapies of warm intravenous fluids, orogastric, bladder, and peritoneal lavages. After 20 minutes, despite these interventions, her core body temperature had risen by only 1°C. She was placed on veno-arterial (VA) ECMO through femoral vessel cannulation for active re-warming and circulatory support. Her core body temperature reached 36°C within 30 minutes and a normal sinus rhythm was spontaneously achieved after 37 minutes of CPR.
She was maintained on ECMO support for the next 10 hours. The patient had a prolonged hospital course secondary to bilateral compartment syndrome, rhabdomyolysis, and frostbite injuries to her feet, and she eventually underwent bilateral transmetatarsal amputations. On day 37, the patient was discharged, with preserved neurologic function, to an acute rehabilitation facility.
Case 2
A 26-year-old intoxicated male was transferred to the ED from an outside facility after being found in a snow bank with a core body temperature of 21.7°C, a GCS of 3, and an asystolic cardiac rhythm. At the time of presentation, he had undergone three hours of continuous CPR. Standard warming therapies were already in place upon arrival and he was cannulated for VA ECMO using his femoral vessels 30 minutes post-presentation. He was re-warmed to 28.8°C 46 minutes later and his cardiac rhythm was noted to be VF. He was defibrillated three times at 150J and achieved a normal sinus rhythm after 265 minutes of CPR. He achieved goal body temperature of 34°C after 90 minutes of ECMO. His resuscitation was complicated by massive pulmonary edema. A right internal jugular dual lumen catheter was placed and the ECMO circuit was converted from VA to veno-venous (VV) to assist with oxygenation. He was maintained on VV ECMO for three days post-arrest.
His hospital course was complicated by acute renal failure, frost bite with transmetatarsal and multiple finger amputations, and tracheostomy and PEG tube placement. On day 57, the patient was discharged, with the ability to follow simple commands, to a long-term care facility.
Case 3
A 21-year-old male presented to the ED as a heroin overdose having been found outside his home with an initial temperature of 27.2°C and a GCS of 6. Standard warming therapies were initiated and he was transferred to the medical intensive care unit 135 minutes post-presentation with a recorded temperature of 29°C. He developed atrial fibrillation and refractory hypotension despite the initiation of four vasoactive medications. Cardioversion was attempted but was unsuccessful. He was cannulated for VV ECMO with a dual lumen right internal jugular catheter 6.5 hours post-presentation and rewarmed to 37°C four hours later. He was weaned from all vasoactive medications 17 hours later and decannulated from ECMO by hospital day five. His hospital course was complicated by aspiration pneumonia, acute respiratory distress syndrome, deep vein thrombosis of the left internal jugular vein, vocal cord dysfunction, and tracheostomy and PEG tube placement. On day 45, he was discharged home with preserved neurologic function.
Discussion
Re-warming therapies are classified as either passive (warm blankets and overhead heaters) or active (infusion of warm fluids and lavage of the peritoneal and thoracic cavities)Reference Freude, Gillen and Ehnert 5 with active methods recommended for severe hypothermia. In hypothermic cardiac arrest, the time to regain normal body temperature is the most influential parameter for a good recovery.Reference Niehaus, Pechulis, Wu, Frei, Hong, Sandhu and Greenberg 1 A recent study found an association between ECMO in CPR and higher survival rates with good neurologic outcomes. 6 In two of these cases, the use of VA ECMO rapidly re-warmed the patients’ core body temperature and provided hemodynamic support in the peri-arrest period. In the third case, VV ECMO was used to re-warm the patient and prevent cardiac deterioration. All three of these cases were young adults with substance use related to their presentation (ethyl alcohol or heroin). The outcomes found may be impacted by this selection bias. The risk of hypothermia is increased by drug ingestion,Reference Stub, Bernard and Pellegrino 7 and particularly with the public health crisis of increasing deaths from overdoses;Reference Soar, Perkins and Abbas 8 it may be worthy to see if earlier ECMO could lead to greater survival rates.
Extracorporeal membrane oxygenation has been shown to have a 6.6-fold higher chance of survival as compared to standard extracorporeal resuscitation. 9 It seems reasonable that ECMO should be considered for re-warming in all patients who present with severe accidental hypothermia and refractory circulatory collapse. Not all cardiothoracic centers have the capacity to provide ECMO support. The triage of hypothermic patients to departments that use this assist device and protocols designed to enhance the preemptive strategy of ECMO has been suggested in cardiothoracic, medicine, and pediatric surgery literature. 9 - Reference Scaife, Connors and Morris 11 However, in the United States, these initiatives have yet to be implemented consistently as standard of care in prehospital EMS practice. Even in systems with protocols for triage to ECMO centers, the dependability is probably impacted by the patient’s presentation. For instance, it is cognitively easier to recognize that a patient with an acute stroke can benefit from care at a stroke center. There are still recognition barriers to assessing the presence of hypothermia in a patient that presents as an unresponsive drug overdose.
While these cases show how the use of ECMO can be a life-saving therapy in patients suffering circulatory collapse due to hypothermia, the recent publication of the CHEER trial has provided evidence to support the use of VA ECMO in other cases of refractory cardiopulmonary collapse. 6 The goal of this report was to encourage continued discussion and education to raise awareness of this important issue for both prehospital and in-hospital providers.
Conclusion
The early transport or transfer of these patients to ECMO-capable centers is important and may be life-saving. Additionally, the hope is that these cases will encourage further research into the utility of ECMO utilization in the ED.
