CASE SERIES OF SEVERE ACCIDENTAL HYPOTHERMIC CARDIAC ARREST TREATED SUCCESSFULLY WITH CARDIOPULMONARY BYPASS IN A UNIVERSITY HOSPITAL IN UNITED KINGDOM

Abstract

Introduction Accidental hypothermia is unintentional decrease in body temperature below 35°C. Severe hypothermia is when temperature drops below 28°C and have a high mortality rate. Methods Case 1 A 48 year old man suspected CVA fall into freezing canal. He was clinging on the side of canal. He developed cardiac arrest when retrieved by crew. Three unsuccessful shocks administered. His temperature was 21° C in ED. A midline sternotomy performed and CPB achieved. He was slowly rewarmed and acidosis corrected. When temperature was 27.5° C,internal DC Cardioversion delivered, reverted him to sinus rhythm. He was successfully weaned of CPB. Total CPB time was 4 hours and 38 min. The patient was extubated next day. He had mild dysarthria and expressive dysphasia. He was discharged to stoke unit on day 3 and improved after stroke rehabilitation. Case 2 A 53 year old female, with previous history of mental illness, found unresponsive adjacent to reservoir, with weighted bag and ankles tied with chains and padlocks. She had cardiac arrest and temperature recorded as 14.1°C. She was airlifted to ED. Initial ABG pH 7.23, Lactate 2.5 and K of 4.0. No shockable rhythm achieved. She was profoundly coagulopathic with INR>10, APTT ratio>5 and Fibrinogen level A femoro-femoral bypass was done. She was slowly rewarmed, coagulopathy and acidosis corrected. She was severely vasoplegic and developed pulmonary oedema. At temperature of 28°C, developed sinus rhythm. She was successfully weaned off CPB after six hours with high doses of vasopressors. She developed TRALI and was ventilated for 12 days. She was confused, withdrawn and non-engaging with staff, with no focal neurological signs and a normal EEG. She received mental health support and rehabilitation and was discharged to a mental health unit on day 30. Results Severe accidental hypothermia is associated with high mortality rate ranging from 30-80% [1]. The neurological outcomes of the survivors are usually good, when the reason for cardiac arrest is not asphyxia. There are retrospective observational studies suggesting prognostic indicators which may predict survival on admission to hospital. Hyperkalemia, pH 400, increased ammonia levels and raised PaCO2 are bad prognostic indicators. A study by Eich et al showed that early initiation of basic life support, hypokalemia, female gender and slow rewarming to be indicators of superior outcomes. CPB is recommended for hypothermic patients in arrest and for patients with core temperatures lower than 25°C. CPB and ECMO has encouraging survival rate of unto 63%. CPB ensures controlled gradual increase in core body temperature and adequate tissue oxygenation. Discussion This case series demonstrates successful recovery with good neurological outcome from severe accidental hypothermic cardiac arrest with CPB in our institution over one year period. For severe hypothermia, CPB is extremely useful treatment device. The prognostic indicators are unclear and more evidence is required.