Aim

Early downward temperature drift is a common event of pre-hospital extracorporeal cardiopulmonary resuscitation (e-CPR), since prehospital extracorporeal membrane oxygenation (VA-ECMO) circuits often lack heat-exchangers. However, whether this core body temperature evolution could be detrimental or beneficial compared to strict normothermia in this context remains unclear. Accordingly, in a swine model of refractory cardiac arrest, we compared e-CPR with heat-exchanger-assisted active maintenance of normothermia versus e-CPR with no temperature regulating device.

Methods and results

Female pigs underwent ventricular fibrillation with 15 min of no-flow and subsequent e-CPR using VA-ECMO. Animals were randomized (n = 6 per group) to receive either active normothermia (with heat-exchanger connected to the VA-ECMO circuit) or no temperature control (without heat-exchanger). Fluids and vasopressor requirements, hemodynamics, ECMO parameters, blood gases, and ultra early impact on target organs biomarkers were monitored for 120 min after return of spontaneous beating (ROSB). Core temperature was significantly lower in the group without heat-exchanger use (36.1 ± 0.3 vs. 37.5 ± 0.3 °C, p = 0.0002). However, fluid requirements, vasopressor doses, heart rate, arterial pressure, intracranial pressure and ECMO flow were similar between groups. Blood gases and biomarkers (including troponin I, creatinine, ALAT and Protein S100β) showed no relevant differences.

Conclusions

Withholding active temperature regulation during early VA-ECMO after refractory cardiac arrest resulted in lower core temperatures but did not significantly affect macrohemodynamics, ECMO flow, fluids/vasopressor needs, or ultra early impact on target organs biomarkers. The short use of simplified ECMO circuits without active temperature management does not appear to result in severe hypothermia or major early hemodynamic instability over a clinically realistic transport like timeframe.