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Methods: Lung oxygen consumption was determined in 16 patients undergoing cardiac surgery. During total cardiopulmonary bypass their lungs were ventilated with low minute volumes (tidal volume, 150 ml; rate, 6 min sup -1; inspiratory oxygen fraction, 0.5; positive end-expiratory pressure, 3 mmHg). All expiratory gas was collected and analyzed by indirect calorimetry. As a reference value also, whole-body oxygen consumption of these patients was determined before total cardiopulmonary bypass. In a pilot study of eight additional patients (same ventilatory pattern), the contribution of systemic (bronchial) blood flow to pulmonary gas exchange during cardiopulmonary bypass was assessed. For this purpose, the amount of enflurane diffusing from the systemic blood into the bronchial system was measured.
Results: The human lung consumes about 5-6 ml oxygen per minute at an esophageal temperature of 28 degrees Celsius. Prebypass whole-body oxygen consumption measured at nearly normothermic conditions was 198 +/- 28 ml/min. Mean lung and whole-body respiratory quotients were similar (0.84 and 0.77, respectively). Extrapolating lung oxygen consumption to 36 degrees Celsius suggests that the lung consumes about 11 ml/min or about 5% of total body oxygen consumption. Because the amount of enflurane diffused from the systemic circulation into the bronchial system during cardiopulmonary bypass was less than 0.1%, the contribution of bronchial blood flow to lung gas exchange can be assumed to be negligible. 相似文献
We have used nitric oxide in the treatment of four children admitted to the paediatric intensive care unit with acute, severe respiratory failure. Administration resulted in an improvement in arterial oxygenation range 1.3–18.4 kPa (9.9–140 mmHg): mean 6.7 kPa (51 mmHg) and a reduction in arterial carbon dioxide tension range 0.6–1.2 kPa (4.5–9 mmHg): mean 0.9 kPa (6.8 mmHg). No adverse effects were encountered following administration for a duration of 3–12 days at a dose of 40–64 parts per million. 相似文献