Comparison of pressure and volume-controlled ventilation in laparoscopic cholecystectomy operations

Laparoscopic cholecystectomy has many advantages such as shorter hospital stay of patients, minimal postoperative pain, rapid recovery after the operation; however, systemic disadvantages because intra-abdominal pressure, position and general anaesthesia may also appear. In this study, pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) modes during laparoscopic cholecystectomy operations were compared in terms of their effects on haemodynamic, respiratory and blood gas parameters.

Patients were randomly assigned to two groups according to the modes of mechanical ventilation, either to the PCV group, group P (35 patients) or to the VCV group, group V (35 patients). A standard electrocardiogram, pulse oximetry, non-invasive blood pressure, end-tidal CO2 , BIS and TOF monitoring were performed. Anaesthesia was induced with propofol, fentanyl and rocuronium. Anaesthesia was maintained with 50% O2  + 50% N2 O, propofol infusion and fentanyl. Haemodynamic data, respiratory parameters, arterial blood gases of the patients were measured. Dynamic compliance of the respiratory system, oxygenation index, alveolar-arterial oxygen gradient and dead space ventilation to tidal volume ratio were calculated.

No difference was detected between the groups in terms of descriptive data, operation, anaesthesia, pneumoperitoneum and recovery period (P > 0.05). Haemodynamic data and blood gas values were compared between the two groups, and no significant difference was found (P < 0.05). After pneumoperitoneum, lung compliance decreased in both groups, more importantly in the Group P (P > 0.05). Tidal volume increased 10 min and 20 min after insufflation in the Group V (P < 0.05). Alveolar dead space ventilation to tidal volume ratio before pneumoperitoneum and alveolar-arterial oxygen gradient after pneumoperitoneum were significantly higher in the Group P compared to the Group V (P < 0.05). Dynamic compliance of the respiratory system was similar in both groups.

In this study, with volume-controlled ventilation anaesthesia in laparoscopic cholecystectomy, higher tidal volume and lower alveolar-arterial oxygen gradient were achieved after pneumoperitoneum. These findings indicated that VCV mode can provide a better alveolar ventilation than PCV mode in laparoscopic cholecystectomy operations.