Ultrarapid Induction of Hypothermia Using Continuous Automated Peritoneal Lavage With Ice-Cold Fluids: Final Results of the Cooling for Cardiac Arrest or Acute ST-Elevation Myocardial Infarction Trial.

OBJECTIVES: Hypothermia (32-34 °C) can mitigate ischemic brain injury, and some evidence suggests that it can reduce infarct size in acute myocardial infarction and acute ischemic stroke. For some indications, speed of cooling may be crucial in determining efficacy. We performed a multicenter prospective intervention study to test an ultrarapid cooling technology, the Velomedix Automated Peritoneal Lavage System using ice-cold fluids continuously circulating through the peritoneal cavity to rapidly induce and maintain hypothermia in comatose patients after cardiac arrest and a small number of awake patients with acute myocardial infarction.

DESIGN: Multicenter prospective intervention study.

SETTING: Intensive care- and coronary care units of multiple tertiary referral centers.

MEASUREMENTS AND MAIN RESULTS: Access to the peritoneal cavity was gained using a modified blunt dilating instrument, followed by catheter placement. Patients were cooled to a temperature of 32.5 °C, maintained for 24 hours (cardiac arrest) or 3 hours (acute myocardial infarction) followed by controlled rewarming. Forty-nine patients were enrolled, and 46 patients completed treatment. One placement was unsuccessful (abdominal wall not breached), two patients were ultimately not cooled, and only safety data are reported. Average catheter insertion time was 2.3 minutes. Mean time to temperature less than 33 °C was 10.4 minutes (average cooling rate, 14 °C/hr). Median infarct size in patients who had coronary interventions was 16% of LV. No cases of stent thrombosis occurred. Survival in cardiac arrest patients with initial rhythm of ventricular tachycardia/ventricular fibrillation was 56%, of whom 82 had a complete neurologic recovery. This compares favorably to outcomes from previous studies.

CONCLUSION: Automated peritoneal lavage system is a safe and ultrarapid method to induce and maintain hypothermia, which appears feasible in cardiac arrest patients and awake patients with acute myocardial infarction. The shivering response appeared to be delayed and much reduced with this technology, diminishing metabolic disorders associated with cooling and minimizing sedation requirement. Our data suggest that ultrarapid cooling could prevent subtle neurologic damage compared with slower cooling. This will need to be confirmed in direct comparative studies.