Cerebral Arterial Air Embolism. 1. Is There Benefit in Beginning HBO Treatment at 6 Bar

摘要

This paper reports one part of our investigations into some of the questions related to pressure and oxygen treatment of arterial gas embolism. The experiments reported were a direct comparison of modified versions of U.S. Navy (USN) Treatment Tables 6 and 6A, two of several treatments in current use. The modification came from consideration of the relative smallness of dogs compared with humans, which suggested the possibility of surfacing directly from 2.8 bar (60 ft) at the end of 90 min. Injection of air into the common carotid artery produces variable effects on electroencephalogram (EEG) and local cerebral blood flow due to a variable distribution of embolic air (22-25). Direct injection into the internal carotid artery with small doses given slowly and flushed with saline produces a more certain effect although it is recognized that not all the air enters the middle cerebral artery. The maximum effect after a small injection of blood foam has been seen at 1 min. The work so far described suggested the best approach to be cannulation of one internal carotid artery through which a small amount of air would be injected. Embolization from this site has the advantage that any observed neurological disturbance only be the result of local events, as no other system is involved. Cortical somatosensory evoked potentials (CEP) were used to provide a quantifiable index of cortical function acutely related to cerebral blood flow.