Lung mechanics during video-assisted abdominal surgery in Trendelenburg position: a cross-sectional propensity-matched comparison between classic laparoscopy and robotic-assisted surgery

Background Video-assisted surgery has become an increasingly used surgical technique in patients undergoing major thoracic and abdominal surgery and is associated with significant perioperative respiratory and cardiovascular changes. The aim of this study was to investigate the effect of intraoperative pneumoperitoneum during video-assisted surgery on respiratory physiology in patients undergoing robotic-assisted surgery compared to patients undergoing classic laparoscopy in Trendelenburg position. Methods Twenty-five patients undergoing robotic-assisted surgery (RAS) were compared with twenty patients undergoing classic laparoscopy (LAS). Intraoperative ventilatory parameters (lung compliance and plateau airway pressure) were recorded at five specific timepoints: after induction of anesthesia, after carbon dioxide (CO 2 ) insufflation, one-hour, and two-hours into surgery and at the end of surgery. At the same time, arterial and end-tidal CO 2 values were noted and arterial to end-tidal CO 2 gradient was calculated. Results We observed a statistically significant difference in plateau pressure between RAS and LAS at one-hour (26.2 ± 4.5 cmH 2 O vs. 20.2 ± 3.5 cmH 2 O, p = 0.05) and two-hour intervals (25.2 ± 5.7 cmH 2 O vs. 17.9 ± 3.1 cmH 2 O, p = 0.01) during surgery and at the end of surgery (19.9 ± 5.0 cmH 2 O vs. 17.0 ± 2.7 cmH 2 O, p = 0.02). Significant changes in lung compliance were also observed between groups at one-hour (28.2 ± 8.5 mL/cmH 2 O vs. 40.5 ± 13.9 mL/cmH 2 O, p = 0.01) and two-hour intervals (26.2 ± 7.8 mL/cmH 2 O vs. 54.6 ± 16.9 mL/cmH 2 O, p = 0.01) and at the end of surgery (36.3 ± 9.9 mL/cmH 2 O vs. 58.2 ± 21.3 mL/cmH 2 O, p = 0.01). At the end of surgery, plateau pressures remained higher than preoperative values in both groups, but lung compliance remained significantly lower than preoperative values only in patients undergoing RAS with a mean 24% change compared to 1.7% change in the LAS group ( p = 0.01). We also noted a more significant arterial to end-tidal CO 2 gradient in the RAS group compared to LAS group at one-hour (12.9 ± 4.5 mmHg vs. 7.4 ± 4.4 mmHg, p = 0.02) and two-hours interval (15.2 ± 4.5 mmHg vs. 7.7 ± 4.9 mmHg, p = 0.02), as well as at the end of surgery (11.0 ± 6.6 mmHg vs. 7.0 ± 4.6 mmHg, p = 0.03). Conclusion Video-assisted surgery is associated with significant changes in lung mechanics after induction of pneumoperitoneum. The observed changes are more severe and longer-lasting in patients undergoing robotic-assisted surgery compared to classic laparoscopy.