The Annals of thoracic surgery
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In an experimental study using 6 pigs, the clinical situation of accidental air embolism was mimicked by introducing a known amount of pure nitrogen into the aortic perfusion line during standard hypothermic cardiopulmonary bypass. The treatment after embolization consisted of 15 minutes of perfusion flow reversal. A special device was built to enable quantitative assessment of the amount of gas that escaped through the aortic cannula during venoarterial perfusion. ⋯ However, microscopic and histological examinations of the brain of each pig one week post-operatively did not reveal trapped gas or ischemic tissue damage. It is concluded that hyperbaric treatment after a clinical accident involving air embolism should be used if the embolus has reached the periphery before flow reversal can be effected. Since over 50% of the amount of gas introduced into the vasculature may remain behind even after prolonged venoarterial perfusion, ischemic damage of organs is still possible.
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We studied both experimentally and clinically the efficacy of partial bypass techniques in maintaining spinal cord blood flow and physiological function during surgical procedures on the thoracoabdominal aorta. We attempted to define the level of distal aortic pressure required to safely ensure normal neurological function in the absence of critical intercostal occlusion. Six dogs underwent left thoracotomy with baseline measurements of spinal cord blood flow and spinal cord impulse conduction (somatosensory evoked potentials). ⋯ We conclude that maintenance of a distal aortic pressure greater than 60 to 70 mm Hg will uniformly preserve spinal cord blood flow in the absence of critical intercostal exclusion. Should distal aortic pressure be inadequate, early reversible changes in the somatosensory evoked potential will alert the surgeon. Failure to institute measures to reverse these changes may result in paraplegia.