Abstract 100: Feasibility of Selective Brain Cooling during Cardiac Arrest: A Novel Nasopharyngeal Approach
Introduction: In patients with cardiac arrest, selective brain cooling may improve neurological outcome, especially if applied prior to reperfusion. Thus it is important to develop practically feasible, non-invasive cooling methods for out-of-hospital use.
Purpose: Pilot study to test whether a novel nasopharyngeal cooling device leads to selective brain cooling during cardiac arrest.
Methods: Domestic swine (35 kg) were anesthetized and routine respiratory and cardiovascular parameters were monitored and recorded. Temperature data were collected from various sites including the forebrain and rectum. After preparation, the cooling device was activated for a duration of 60 minutes. The device consists of two capped plastic tubes that are advanced through the nostrils so that the tip is located in the nasopharynx. A mixture of oxygen (40 L/min) and perfluorocarbon (0.28 ml/L oxygen) is conducted through the tubes and escapes through small openings in the nasopharyngeal area as perfluorocarbon mist. Rapid evaporation of the perfluorocarbon leads to cooling of the area. Thermokinetic properties of the device were examined in two animals during stable anesthesia and in one animal during untreated cardiac arrest.
Results: In the animal with cardiac arrest, the brain temperature decreased by 4.82°C within 60 minutes, while rectal temperature decreased only by 0.37°C. In the two animals with intact circulation a comparable decrease in brain temperature (4.86°C and 4.66°C) with a more marked drop in the rectal temperature (2.66°C and 2.78°C) were achieved. The brain cooling rate remained constant in the animal with cardiac arrest (−0.08°C/min), but was biphasic in the animals with intact circulation: rapid during the first 5 minutes (−0.29°C/min; −0.31°C/min), slower thereafter (−0.04°C/min; − 0.05°C/min).
Conclusion: Initial data from this pilot study examining a novel non-invasive cooling method in an experimental setting suggests that cooling of the brain in large animals with cardiac arrest is possible. The cooling process is expected to be preferential to the brain in the no-flow condition, while mild systemic hypothermia may be achieved during normal blood flow. Further testing of this method is warranted and will be conducted in our laboratory.