Register S D, Downs J B, Stock M C, Kirby R R
Crit Care Med. 1987 Jun;15(6):598-601. doi: 10.1097/00003246-198706000-00012.
Pulmonary gas exchange after tracheal extubation was evaluated in 25 patients to determine the effect of 50% oxygen administered during mechanical ventilation following aortocoronary bypass grafting. Twenty-five patients received postoperative mechanical ventilation for 16 to 24 h, 13 with an inspired oxygen fraction (FIO2) of no more than 0.30 and 12 with an FIO2 of 0.50. After tracheal extubation, all patients spontaneously breathed room air (FIO2 0.21). Postextubation the calculated venous admixture of patients who had received 50% oxygen (0.20 +/- 0.03 [SD]) was significantly (p less than .01) greater than that calculated for patients who received lower oxygen concentrations (0.13 +/- 0.04). Consequently, the PaO2 of patients who had received 50% oxygen (60 +/- 5 torr) was significantly (p less than .03) lower than the PaO2 of patients who had received no more than 30% oxygen (66 +/- 7 torr). Thus, administration of 50% oxygen, supposedly nontoxic, to mechanically ventilated patients may cause impairment of pulmonary gas exchange after tracheal extubation. Although high concentrations of supplemental oxygen are sometimes required, unnecessary elevation of FIO2 is not likely to significantly increase oxygen delivery and may contribute to postextubation pulmonary dysfunction.
对25例患者进行气管插管拔管后的肺气体交换评估，以确定在主动脉冠状动脉搭桥术后机械通气期间给予50%氧气的效果。25例患者术后接受机械通气16至24小时，其中13例吸入氧分数（FIO2）不超过0.30，12例FIO2为0.50。气管插管拔管后，所有患者自主呼吸室内空气（FIO2 0.21）。拔管后，接受50%氧气的患者计算出的静脉血掺杂（0.20±0.03[标准差]）显著（p<0.01）高于接受较低氧浓度的患者（0.13±0.04）。因此，接受50%氧气的患者的动脉血氧分压（PaO2）（60±5托）显著（p<0.03）低于接受不超过30%氧气的患者（66±7托）。因此，向机械通气患者给予据认为无毒的50%氧气可能会导致气管插管拔管后肺气体交换受损。虽然有时需要高浓度的补充氧气，但不必要地提高FIO2不太可能显著增加氧输送，且可能导致拔管后肺功能障碍。
