Comparison Of Pressure-controlled And Volume-controlled Lung Protective Ventilation In Elderly Patients Undergoing General Anesthesia For Major Abdominal Laparoscopic Surgery

Objective To investigate the effects of different models of lung protective ventilation in elderly patients undergoing general anesthesia for major abdominal laparoscopic surgery.Methods One hundred patients (aged 65-85yr) undergoing general anesthesia for major abdominal laparoscopic surgery(with operation time ranging 2hrs-8hrs) were assigned in this prospective randomized controlled trial. Patients were randomly divided into pressure-controlled ventilation group (PCV, n=50) or volume-controlled ventilation group (VCV, n=50). The hemodynamics and respiratory mechanics index were measured at different time intervals including heart rate(HR)?mean arterial pressure(MAP)?the peak and mean airway pressure(Ppeak,Pmean)?respiratory rates(RR) and end-tidal expiration carbon dioxide(PetCO2). Arterial blood gas analysis was tested at pre-intubation (T1),after surgery began (T3),2 hr of surgery(T5),and after extubation(T7). Time of activity, removing gastric tube and catheter, as well as aerofluxus, defecation and diet after the operation were recorded. Pulmonary and extrapulmonary complications during hospitalization were recorded. The pulmonary complications included hypoxemia, need for invasive ventilation, pneumonia, acute respiratory injury or acute respiratory distress syndrome(ALI/ARDS) and pleural effusion in the perioperative period. The extrapulmonary complications included systemic inflammatory response syndrome(SIRS); postoperative shivering;unexpected need for admission to the intensive care unit (ICU); extrapulmonary infection; cardiovascular events; and surgical complications, including intraabdominal abscess, anastomotic leakage, and unplanned reoperation.Results Five patients were excluded and 95 patients remained in this trial including 47 patients for PCV group and 48 patients for VCV group. The general information showed no statistical difference between two groups. The PaO2 and the PaO2/FiO2-ratio after the surgery in both groups were significantly lower than that of preoperative,and the PaO2 and the PaO2/FiO2-ratio at T3,T5,T7 in PCV group were significantly higher than that in VCV group (P<0.05); Compared with preoperative,intraoperative HR and MAP were significantly lower in both groups, but there were no significant differences between two groups. Group PCV needed less colloidal fluid than group VCV. The level of Ppeak and Pmean were significantly higher after establishing pneumoperitoneum in each group, and the level of Ppeak in PCV group was significantly lower than that in VCV group (P<0.05). The major pulmonary complications occurred in 10 patients (21.2%) in the group PCV, as compared with 11(22.9%) in the VCV group. The incidence of pulmonary and extrapulmonary complications showed no statistical difference between the two groups during the hospitalization after surgery (P>0.05).Conclusions As compared with VCV, the use of PCV on elderly patients undergoing general anesthesia for major laparoscopic abdominal surgery can lead to lower airway pressure and higher PaO2 and the PaO2/FiO2-ratio. Thus, PCV may benefit for elderly patients undergoing major laparoscopic abdominal surgery.