EFFECTS OF ACUTE-HYPOXIA ON INTRACRANIAL DYNAMICS IN UNANESTHETIZED GOATS

The effects of acute hypoxia on intracranial dynamics were studied in six unanesthetized goats that were subjected to hypobaric hypoxia at a simulated 4,000-m high altitude for 2 h. Another six nonhypoxic goats served as control group for cerebral water content (CWC). In this stu dy, we measured cerebral blood flow (CBF) by electromagnetic flowmeter , intracranial pressure (ICP) through an intraventricular catheter, an d CWC by a wet-to-dry weight technique for a given volume of brain tis sue. Intracranial compliance was calculated from a pressure-volume ind ex derived from the change in intraventricular pressure after a subara chnoid injection of saline. During acute hypoxia CBF increased from 14 6.0 +/- 10.60 to 185.3 +/- 7.83 ml . min-1 . 100 g-1, ICP increased fr om 15.4 +/-1.82 to 27.4 +/- 3.84 cmH2O, and CWC increased from 78.7 +/ - 0.30 to 79.5 +/- 0.16%, but intracranial compliance decreased from 0 .65 +/- 0.28 to 0.36 +/- 0.19 ml/cmH2O. The data suggest that acute hy poxia results in a significant disturbance of intracranial dynamics, w hich may be one of the important pathophysiological mechanisms of high -altitude cerebral edema and acute mountain sickness.