Chest
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This study was undertaken to determine whether an infusion of local anesthetic (LA) delivered through an extrapleural tunnel could provide satisfactory control of pain in the postthoracotomy period. Twelve patients undergoing thoracotomy were studied. A T-shaped tunnel was created by elevating the parietal pleura at the posteromedial end of the thoracotomy wound. ⋯ Pain was well controlled in eight patients and satisfactory in four patients. The latter required one dose of opiate analgesia each in the 48-h postoperative period. We conclude that an infusion of bupivacaine into the extrapleural space is an effective means of control of pain after thoracotomy.
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To assess the responsiveness of mixed venous oximetry under conditions of supply-independent and supply-dependent oxygen consumption, we subjected ten pigs to graded isovolemic hemodilution while measuring cardiopulmonary variables, including oxygen consumption (VO2), oxygen delivery (DO2), and mixed venous oxyhemoglobin saturation (SvO2). Supply-dependent VO2 was reached at an average hemoglobin concentration of 3.9 +/- 0.7 g.dl-1, an SvO2 of 38.2 +/- 8.1 percent, and an oxygen extraction ratio of 0.55 +/- 0.10. ⋯ However, the rate of decline in SvO2 in the supply-dependent range was significantly slower than the rate calculated assuming unchanged VO2 (-32.6 +/- 16.3 percent; p less than 0.01). The results indicate that appearance of supply-dependence of VO2 does not render mixed venous oximetry unresponsive to further deterioration of oxygen supply during isovolemic hemodilution.