Intraoperative dorsal lung ventilation reduction and postoperative pulmonary complications

In a prospective cohort of 91 patients undergoing laparoscopic colorectal cancer surgery, electrical impedance tomography (EIT) quantified the ratio of dorsal ventilation (RDV). A ≥14.5% reduction in RDV from baseline to surgery end (RDV_T0–T3) was associated with higher PPC rates and longer hospital stay. RDV_T0–T3 ≥14.5% was independently associated with PPCs (adjusted OR 11.28; 95% CI 2.58–49.25). These results establish a clinically applicable threshold, supporting EIT-guided individualized lung-protective ventilation strategies.

Postoperative pulmonary complications (PPCs) are prevalent adverse events following major surgery, closely associated with prolonged hospital stay and elevated perioperative morbidity and mortality. Early identification of high-risk patients and precise and effective pulmonary protection remain key challenges in perioperative medicine.

Mechanical ventilation during general anesthesia alters the physiological distribution of pulmonary ventilation. Compared with spontaneous breathing in the awake state, ventilation during anesthesia is redistributed toward the ventral regions of the lung, accompanied by a reduction in ventilation within the dorsal dependent regions. Electrical impedance tomography (EIT) monitoring has also shown that, following endotracheal intubation, tidal ventilation distribution shifts markedly toward the ventral lung regions, whereas aeration within the dorsal dependent lung regions decreases substantially. However, whether this intraoperative heterogeneity in regional lung ventilation is associated with the development of PPCs in surgical patients remains unclear.

A recent prospective cohort study conducted by the team of Professor Xiangming Fang from Zhejiang University School of Medicine, China, and Professor Guohao Xie from the First Affiliated Hospital, Zhejiang University School of Medicine, has established a strong association between intraoperative dorsal lung ventilation reduction and PPCs in patients undergoing laparoscopic colorectal cancer surgery, using EIT for real-time regional ventilation monitoring. Their findings were made available online on August 14, 2026, and will be published in the Chinese Medical Journal on August 14, 2026.

The study enrolled 91 patients undergoing elective laparoscopic colorectal cancer surgery. EIT was applied to measure the ratio of dorsal ventilation (RDV) at four time points: 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). The magnitude of RDV reduction relative to T0 was calculated.

“Data revealed that general anesthesia caused significant ventilation redistribution, with markedly reduced dorsal aeration, which was further aggravated by body position change and pneumoperitoneum,” says Prof. Xie. Patients with a reduction of dorsal lung ventilation at T3 (RDV_T0–T3) ≥14.5% had a 54.8% incidence of PPCs within 7 days postoperatively, compared with only 18.3% in patients with RDV_T0–T3 <14.5%. These patients (RDV_T0–T3 ≥14.5%) also presented lower PaO₂/FiO₂ at T3 and a longer hospital stay. Multivariable logistic regression confirmed that a high reduction of RDV_T0–T3 (≥14.5%) was an independent risk factor for PPCs (adjusted OR 11.28, 95% CI: 2.58–49.25).

“This study demonstrates the ability of non-invasive EIT technology to achieve real-time visualization and quantitative assessment of intraoperative lung ventilation, establishing RDV_T0-T3 ≥14.5% as a critical early warning threshold,” says Prof. Xie. This provides new evidence for early risk stratification and precise perioperative lung management in abdominal surgery. “The findings will support personalized lung-protective ventilation strategies, such as optimized PEEP and recruitment maneuvers, to reduce dorsal atelectasis and improve postoperative outcomes, thereby enhancing postoperative recovery, shortening hospital stays, and demonstrating significant clinical translational value,” says Prof. Fang.

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Reference

DOI:  10.1097/CM9.0000000000004197

About Dr. Guohao Xie from The First Affiliated Hospital, School of Medicine, Zhejiang University, China

Dr. Guohao Xie, M.D., is a chief physician and Deputy Director of the Department of Anesthesiology at the First Affiliated Hospital, Zhejiang University School of Medicine (Yuhang Campus). He also serves as Vice-Chair of the Medical Education Branch of the Chinese Society of Cardiothoracic and Vascular Anesthesia. His research focuses on the clinical and basic science of sepsis and critical illness, as well as perioperative organ protection. He has been the principal investigator for two National Natural Science Foundation of China grants, has authored over 20 SCI‑indexed publications, and has contributed to three medical monographs.

Funding information

This work was supported by the grants from the National Natural Science Foundation of China (Nos. 82102238, U24A20714).