Intraoperative dorsal lung ventilation reduction and postoperative pulmonary complications after laparoscopic...

Postoperative pulmonary complications (PPCs) remain common following surgery and contribute substantially to postoperative morbidity. Reduced ventilation in the dorsal lung regions, reflecting dorsal atelectasis during mechanical ventilation after anesthesia induction, may increase the risk of PPCs. This study aimed to investigate the association between intraoperative reduction in dorsal lung ventilation and the development of PPCs.

Patients undergoing laparoscopic colorectal cancer surgery were enrolled, and intraoperative regional lung ventilation was assessed using electrical impedance tomography. The ratio of dorsal ventilation (RDV) was measured at spontaneous breathing in the awake state (T0), after anesthesia induction and endotracheal intubation (T1), after body position change and pneumoperitoneum (T2), and at the end of surgery (T3). Using T0 as the baseline reference, the proportion of reduced dorsal ventilation was calculated and defined as RDVT0-T1, RDVT0-T2, and RDVT0-T3. Demographic, intraoperative, and postoperative data were collected, and PPCs occurring within 7 days after surgery were recorded. The predictive performance of reduced dorsal ventilation for PPCs was evaluated using receiver operating characteristic (ROC) curve analysis, and group allocation was determined using the optimal cut-off value derived from the Youden index. Clinical outcomes, including the incidence of PPCs and postoperative length of hospital stay, were compared between groups. Logistic regression analysis was performed to identify factors independently associated with PPCs.

A total of 91 patients from the First Affiliated Hospital, School of Medicine, Zhejiang University were included in the final analysis (median age 67.0 years, median body mass index 22.6 kg/m2, 33.0% of women). Relative to RDVT0-T1 and RDVT0-T2, RDVT0-T3 exhibited maximal area under the ROC curve. Patients were therefore classified into two groups: group 1 (higher reduction of RDVT0-T3, RDVT0-T3 ≥14.5%) and group 2 (lower reduction of RDVT0-T3, RDVT0-T3 <14.5%). Group 1 had a higher incidence of PPCs (54.8% vs. 18.3%, P <0.001), and a lower ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) at T3 (365.2 ± 93.3 mmHg vs. 404.5 ± 56.5 mmHg, P = 0.040) than group 2. The median postoperative length of hospital stay was also longer in group 1 (median 9.0, interquartile range [IQR] [7.8-11.0] days vs. median 8.0, IQR [7.0-9.0] days, P = 0.006). In multivariable logistic regression analysis, a high reduction of RDVT0-T3 remained independently associated with the development of PPCs (adjusted odds ratio, 11.28; 95% confidence interval [CI], 2.58-49.25; P = 0.001).

A high reduction of RDVT0-T3 is independently associated with the development of PPCs in patients undergoing laparoscopic colorectal cancer surgery.

https://clinicaltrials.gov/, NCT06662799.