Objective:To evaluate the lung protection of pressure-controlled ventilation volume guaranteed (PCV-VG) in elderly patients undergoing laparoscopic surgery in Trendelenburg position.Methods:Sixty patients of American Society of Anesthesiologists physical status Ⅰ-Ⅲ, aged 65-80 yr, with body mass index of 19-27 kg/m 2, scheduled for elective laparoscopic radical prostatectomy or laparoscopic radical cystectomy, were allocated into 2 groups ( n=30 each) by a random number table method: VCV group (group V) and PCV-VG group (group P). Tracheal intubation was performed after induction of anesthesia.The anesthesia machine was connected to perform mechanical ventilation with tidal volume of 7 ml/kg (corrected body weight), positive end-expiratory pressure at 5 cmH 2O, inspiratory/expiratory ratio 1∶2, fraction of inspired oxygen 50%, fresh gas flow at 2 L/min and respiratory rate 12-15 breaths/min in two groups.Recruitment maneuver was performed with a pressure of 30 cmH 2O, lasting for 30 s, starting from 5 min before the end of administration.The airway peak pressure (P peak), airway plateau pressure (P plat), driving pressure (DP), and dynamic lung compliance (Cdyn) were measured at 5 min after intubation (T 1), 5 min after changing position (T 2), 5, 30, 60, 90 and 120 min of pneumoperitoneum (T 3-7) and 5 min after restoring the supine position and after the end of pneumoperitoneum (T 8). Blood samples were collected from the radial artery for blood gas analysis at T 1, T 4 and T 6 and when modified Aldrete score reached 10 in postanesthesia care unit, and pH value, partial pressure of arterial oxygen (PaO 2), partial pressure of arterial carbon dioxide (PaCO 2), arterial oxygen saturation (SaO 2) and alveolar-arterial oxygen gradient (P A-aO 2) were recorded.Blood samples were collected from the radial artery before induction of anesthesia and at the end of surgery for determination of concentrations of Clara cell protein (CC-16), interleukin-6 (IL-6) and neutrophil elastase (NE) in serum by enzyme-linked immunosorbent assay.The development of pulmonary complications was recorded within 7 days after surgery. Results:Compared with group V, P peak was significantly decreased at T 1-8, P plat and DP were decreased at T 5-7, Cdyn was increased at T 2-7, P A-aO 2 was decreased at T 1, 4, 6, serum CC-16, IL-6 and NE concentrations were decreased at the end of surgery ( P<0.05), and no significant change was found in the incidence of pulmonary complications within 7 days after surgery in group P ( P>0.05). Conclusion:PCV-VG can produce lung protection to some extent in elderly patients undergoing laparoscopic surgery in Trendelenburg position.