Transpulmonary Hypothermia with Cooled Oxygen Inhalation Shows Promising Results as a Novel Hypothermia Technique.

Background: Therapeutic hypothermia was showed to improve neurologic outcome but current therapeutic hypothermia techniques have limitations. Novel techniques such as transpulmonary hypothermia with cooled oxygen inhalation may be beneficial.

Aims: To evaluate the performance of transthoracic hypothermia with cooled medical oxygen inhalation as a therapeutic hypothermia method.

Study Design: Animal experimentation.

Methods: A total of 36 adult male Wistar-Hannover rats were used in this research. Rats were randomised into four groups: group 1, Cooled oxygen group; group 2, IV cold fluid group; group 3, Surface cooling group; group 4, control group. No hypothermia method was applied in the control group. Hypothermia techniques were administered in the other three groups until the targeted core temperature was maintained. The target temperature was continued for one hour at 32-34 °C. After that, rats were heated up with hot blankets. Once the rectal temperature reached 38 °C, rats were euthanised. The main outcomes were the rate of temperature decrease (°C per minute) (S) and the time required to reach the target body temperature (T).

Results: All rats survived the study protocol. When compared to the control group, T and S values were better in the cooled medical oxygen inhalation group (p<0.001). The IV cold fluid group had lower S values and higher T values compared to the cooled oxygen group (p<0.001, and p=0.003, respectively). There was no meaningful pathology in the histological samples in any group.

Conclusion: As an easy-to-use and inexpensive method, cooled oxygen inhalation may be a beneficial hypothermia technique.