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Induced hypothermia in post-resuscitation cardiac care

Cardiac arrest and ROSC (return of spontaneous circulation) is a case of whole body ischaemia and subsequent reperfusion injury. Mild hypothermia, defined as core body temperature 32-34 °C has been shown to attenuate and ameliorate deleterious temperature sensitive mechanisms, thereby contributing to protection of the brain and heart. Primary indication (2010th AHA/ACC Guidelines For Cardiopulmonary Resuscitation) is in out-of-hospital cardiac arrest when initial rhythm was ventricular fibrillation or pulseless ventricular tachycardia (Class I, LOE B); in in-hospital cardiac arrest including all other rhythms (asystole and PEA) when, after return of spontaneous circulation, there is no neurologic response (“lack of meaningful response to verbal commands”).

The goal is to achieve IT (induced hypothermia) within 6 hours (starting within 10 min after return of spontaneous circulation) and to maintain it for 12 to 24 hours. Cooling methods: internal- intravenous infusion of 4 °C isotonic saline and external- ice packs, cooling blankets, cooling vests, cold water immersion.

Shivering raises body temperature and must be suppressed. High doses of sedatives must be titrated to suppress shivering (continuous infusion of propofol and fentanyl).

Core body temperature should be closely monitored by esophageal, bladder and rectal temperature probes. After 12-24 hours of maintaining IT the temperature should be raised gradually (at a rate of 0.2-0.25 °C per hour). Rapid rewarming (>0.5° C/hour) eliminates the benefits of IT.

Adverse effects of therapeutic hypothermia are impaired coagulation, increased risk of infection, slowing of cardiac conduction, bradycardia, QT prolongation, “cold diuresis”- hypovolemia, hypokalemia, hypomagnesaemia, hypophosphatemia.

We suggest more prone implementation of induced hypotermia in cardiac ICU due to the ERC statement, “Hypothermia is safe and effective even if there is lack of experience”.

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