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Cardiac Pressure Changes with Venous Gas Embolism and Decompression
Final rept. Nov 1991-Sep 1993
TEXAS UNIV MEDICAL SCHOOL AT HOUSTON DEPT OF ANESTHESIOLOGY
Pagination or Media Count:
Venous air embolism is reported with decompression to a decreased ambient pressure. With severe decompressions or in cases where an intracardiac septal defect patent foramen ovale exists, the venous bubbles can become arterialized and cause neurological decompression illness. Incidence rates of patent foramen ovale in the general population range from 25-34 and yet aviators, astronauts and undersea divers who have decompression-induced venous bubbles do not demonstrate neurological symptoms at these high rates. This apparent disparity may be attributable to the normal pressure gradient across the atria of the heart that must be reversed for there to the be flow patency. We evaluated the effects of 1 venous air embolism 0.025, 0.05 and 0.15 mlkg -1min-1 for 180 min, 2 hyperbaric decompression, and 3 hypobaric decompression on the pressure gradient across the left and right atria. Left ventricular end-diastolic pressure was used as a measure of left atrial pressure. In a total of 92 experimental evaluations, there were no reported reversals in the mean pressure gradient across the atria, and a total of 3 transient reversals in the peak gradient pressures. This disparity may be due to insufficent amounts of venous gas to cause a pressure and hence flow reversal across the atria.
APPROVED FOR PUBLIC RELEASE