Abstract 2624: Inducing Hypothermia After Experimental Cardiac Arrest With Intranasal Cooling Alone Or In Combination With Cold Saline Infusion Is Efficient
Introduction: In a previous experimental study we have shown that intranasal cooling is effective to selectively cool the brain during normal circulation. In cardiac arrest, for neuroprotection, hypothermia should be initiated as fast as possible.
Hypothesis: We hypothesized that intranasal cooling alone or in combination with cold saline infusion would effectively reduce the brain and body temperature after cardiac arrest.
Methods: Twenty anesthetized pigs with a weight 26.5 ± 1.35 kg were instrumented and after a period of stabilization cardiac arrest was induced. They were randomized in two groups and subjected to intranasal cooling alone (n=10) or in combination with cold saline infusion (n=10). Bilaterally introduced nasal balloon catheters were perfused with saline cooled by a heat exchanger to 8 –10°C. In the combined group, saline 30 ml/kg, chilled at 4°C was infused at a rate of 1.33 ml/kg/min. After 8 min of cardiac arrest, CPR was started using mechanical chest compressions (LUCAS) and ventilation with 100% O2. After another 9 min defibrillation was performed to achieve restoration to spontaneous circulation. Cooling was started after 1 min of CPR. Brain temperature was measured in both cerebral hemispheres. Body temperature was measured in rectum, esophagus and right atrium.
Results: One animal in each group did not achieve restoration of spontaneous circulation. Brain temperature was lowered after 30 min cooling with a gradient of 1.4 ± 0.5°C (mean ± SEM) using intranasal cooling and 1.7 ± 0.9°C with the combined method. After 3 hours brain temperature was reduced with 3.6 ± 0.3°C using intranasal cooling and 4.3 ± 1.6°C with combined cooling (p=0.001). Body temperature measured in the esophagus was reduced with a gradient of 0.7 ± 0.6 °C after 30 min and 3.4 ± 0.8°C after 3 hrs in the intranasal l cooling group. In the combined group the body temperature was reduced with a gradient of 1.0 ± 0.9°C after 30 min and 4.3 ± 1.5°C after 3 hrs. No significant difference was observed in brain-body temperature gradients between the two groups (p=0.07).
Conclusion: Intranasal cooling is effective in lowering brain and body temperature after restored circulation from cardiac arrest but the combination with cold saline infusion seems to be even more efficient.