Intranasal selective brain cooling in pigs
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Background: Special clinical situations where general hypothermia cannot be recommended but can be a useful treatment demand a new approach, selective brain cooling. The purpose of this study was to selectively cool the brain with cold saline circulating in balloon catheters introduced into the nasal cavity in pigs. Material and methods: Twelve anaesthetised pigs were subjected to selective cerebral cooling for a period of 6 h. Cerebral temperature was towered by means of bilaterally introduced nasal balloon catheters perfused with saline cooled by a heat exchanger to 8-10 degrees C. Brain temperature was measured in both cerebral hemispheres. Body temperature was measured in rectum, oesophagus and the right atrium. The pigs were normoventilated and haemodynamic variables were measured continuously. Acid-base and electrolyte status was measured hourly. Results: Cerebral hypothermia was induced rapidly and within the first 20 min of cooling cerebral temperature was lowered from 38.1 +/- 0.6 degrees C by a mean of 2.8 +/- 0.6 to 35.3 +/- 0.6 degrees C. Cooling was maintained for 6 h and the final brain temperature was 34.7 +/- 0.9 degrees C. Concomitantly, the body temperature, as reflected by oesophageal temperature was decreased from 38.3 +/- 0. 5 to 36.6 +/- 0.9 degrees C. No circulatory or metabolic disturbances were noted. Conclusions: Inducing selective brain hypothermia with cold saline via nasal balloon catheters can effectively be accomplished in pigs, with no major disturbances in systemic circulation or physiological variables. The temperature gradients between brain and body can be maintained for at least 6 h.