Effects of different mechanical ventilation methods on respiratory function in elderly patients in the steep Trendelenburg position under general anesthesia / 中华老年医学杂志

ABSTRACT

Objective:To investigate the effects of different mechanical ventilation methods on respiratory function in elderly patients in the steep Trendelenburg position undergoing general anesthesia.Methods:This was a randomized controlled study.Sixty patients scheduled for elective laparoscopic radical prostatectomy in the steep Trendelenburg position under general anesthesia were randomly divided into the lung protective ventilation strategy group(the P group)and the traditional ventilation strategy group(the T group)(n=30, each group). The setting for the P group included FiO 2 at 50%, tidal volume at 6 ml/kg, respiratory rate at 14-16/min, positive end expiratory pressure(PEEP)at 5 cmH 2O, with sustained lung inflation by pressure control every 30 min and the pressure at 30 cmH 2O for 30 s. The setting for the T group included FiO 2 at 50%, tidal volume at 10 ml/kg, and respiratory rate at 10-12/min.Anesthesia was maintained by sevoflurane, remifentanil and cis-atracurium.Driving pressure(DP), mean airway pressure(P mean)and end-tidal carbon dioxide(EtCO 2)were recorded at T1(5 mins after intubation), T2(after pneumoperitoneum), T3(30 mins after pneumoperitoneum), T4(1h after pneumoperitoneum), T5(2h after pneumoperitoneum), T6(3h after pneumoperitoneum)and T7(end of surgery). Arterial blood partial pressure of carbon dioxide(PaCO 2), alveolar-arterial oxygen partial pressure difference[P(A-a)O 2]and oxygenation index(OI)were recorded at T0(entering the operating room), T1, T3, T4, T5, T6, T8(after extubation)and T9(24h after operation). Arterial-end-tidal carbon dioxide partial pressure difference[P(a-et)CO 2]was recorded at T3, T4, T5 and T6. Results:DP in the P group was lower than in the T group at each time point( P<0.01). The P mean in the P group at each time point was higher than in the T group( P<0.01). EtCO 2 was higher in the P group than in the T group at T1( t=0.751, P<0.01)and T2( t=2.830, P<0.01). PaCO 2 was higher in the P group than in the T group at T1( t=1.435, P<0.01), T3( t=2.469, P<0.01)and T4( t=1.359, P<0.05). There were no statistic differences in P(A-a)O 2, OI and P(a-et)CO 2 between the two groups at any time point( P>0.05). Conclusions:Compared with the traditional ventilation strategy, the lung protective ventilation strategy has lower DP and higher P mean during laparoscopic radical prostatectomy, while it has no advantage in lung oxygenation.The lung protection ventilation strategy can be safely used in laparoscopic radical prostatectomy in the steep Trendelenburg position under general anesthesia.