Effect of continuous positive airway pressure ventilation during induction of anesthesia on perioperative atelectasis and oxygenation in elderly patients / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of continuous positive airway pressure (CPAP) ventilation during induction of anesthesia on perioperative atelectasis and oxygenation in elderly patients.Methods:Forty-six elderly patients of either sex, aged 65-80 yr, of American Society of Anesthesiologists Physical Status classification Ⅱ or Ⅲ, undergoing elective cerebrovascular intervention surgery under general anesthesia, were divided into 2 groups ( n=23 each) according to the random number table method: control group (group C) and CPAP ventilation group (group CPAP). During induction of anesthesia, CPAP was set at 5 cmH 2O during spontaneous breathing, and PEEP was set at 5 cmH 2O when spontaneous breathing disappeared, and the ventilation mode was changed to pressure-controlled ventilation (PCV) mode in group CPAP. CPAP was not set, and PEEP was set at 0 cmH 2O for PCV when spontaneous breathing disappeared in group C. During anesthesia maintenance, PCV-volume guaranteed mode was used in both groups, and PEEP was set at 5 cmH 2O. Whole lung CT scanning was performed immediately after radial artery catheterization (T 0), at 1 min after endotracheal intubation (T 1), and before tracheal extubation (T 2) at the end of operation to calculate the percentage of atelectasis area at 1 cm above the right diaphragm. At T 0, T 1, T 2 and 30 min after entering postanesthesia care unit (T 3), blood samples from the radial artery were taken to record PaO 2 and PaCO 2 and calculate the oxygenation index (OI). Results:Compared with the baseline at T 0, the percentage of atelectasis area was significantly increased at T 1 and T 2 in two groups ( P<0.05); PaO 2 was significantly increased at T 1 and T 2 and decreased to T 0 level at T 3, OI was decreased at T 1 and T 2 and increased to T 0 level at T 3 in two groups ( P<0.05). Compared with group C, the percentage of atelectasis area was significantly decreased and PaO 2 and OI were increased at T 1 and T 2 in group CPAP ( P<0.05). There was no significant difference in PaCO 2 at each time point between the two groups ( P>0.05). Conclusions:CPAP ventilation during induction of anesthesia can reduce the development of perioperative atelectasis and improve the oxygenation in elderly patients.