Lancet
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Randomized Controlled Trial Clinical Trial
Prevention of atelectasis during general anaesthesia.
Atelectasis is an important cause of impaired gas exchange during general anaesthesia; it causes pulmonary shunting. We studied the effects of gas composition on the formation of atelectasis and on gas exchange during the induction of general anaesthesia. In 12 adult patients, the lungs were ventilated with 30% oxygen in nitrogen during anaesthesia induction, and in another 12, a conventional technique was used (100% oxygen during induction and 40% oxygen in nitrogen thereafter). ⋯ In subgroup B, the shunt increased from 2.6 (5.2)% to 9.8 (5.7)% of cardiac output. These results suggest that the composition of inspired gas is important in atelectasis formation during general anaesthesia. Use of a lower oxygen concentration than is now standard practice might prevent the early formation of atelectasis.