Cold simple intravenous infusions preceding special endovascular cooling for faster induction of mild hypothermia after cardiac arrest—a feasibility study

Abstract

Objective: Mild therapeutic hypothermia has shown to improve neurological outcome after cardiac arrest. Our study investigated the efficacy and safety of cold simple intravenous infusions for induction of hypothermia after cardiac arrest preceding further cooling and maintenance of hypothermia by specialised endovascular cooling. Methods: All patients admitted after cardiac arrest of presumed cardiac aetiology were screened. Patients enrolled received 2000 ml of ice-cold (4 °C) fluids via peripheral venous catheters. As soon as possible endovascular cooling was applied even if the cold infusions were not completed. The target temperature was defined as 33 ± 1 °C. All temperatures recorded were measured via bladder-temperature probes. The primary endpoint was the time from return of spontaneous circulation to reaching the target temperature. Secondary endpoints were changes in haemodynamic variables, oxygenation, haemoglobin, clotting variables and neurological outcome. Results: Out of 167 screened patients 26 (15%) were included. With a total amount of 24 ± 7 ml/kg cold fluid at 4 °C the temperature could be lowered from 35.6 ± 1.3 °C on admission to 33.8 ± 1.1 °C. The target temperature was reached 185 ± 119 min after return of spontaneous circulation, 135 ± 112 min after start of infusion, and 83 ± 85 min after start of endovascular cooling. Except for two patients showing radiographic signs of mild pulmonary edema no complications attributable to the infusions could be observed. Thirteen patients (50%) survived with favourable neurological outcome. Conclusion: Our results indicate that induction of mild hypothermia with infusion of cold fluids preceding endovascular cooling is safe and effective.