Abstract

Introduction: Postoperative pulmonary complications are common after lung cancer surgery in older adults. Individualised positive end-expiratory pressure may optimise intra-operative lung mechanics, but its effect on postoperative pulmonary complications is uncertain. We hypothesised that individualised positive end-expiratory pressure would reduce the incidence of postoperative pulmonary complications compared with a fixed positive end-expiratory pressure in older patients (age ≥ 60 years) undergoing lung cancer surgery.

Methods: In total, 400 patients were allocated randomly to individualised positive end-expiratory pressure (PEEP_IND group) or a fixed positive end-expiratory pressure of 5 cmH₂O (PEEP₅ group). The primary outcome was the incidence of postoperative pulmonary complications. Secondary outcomes included duration of postoperative hospital stay; extrapulmonary complications; 30-day postoperative complications; driving pressure; and oxygenation index.

Results: Median (IQR [range]) individualised positive end-expiratory pressure was 11 (9-11 [3-13]) cmH₂O during one-lung and 9 (7-9 [3-13]) cmH₂O during two-lung ventilation. Patients allocated to the PEEP_IND group had lower driving pressures during one-lung (12 (11-14 [4-23]) vs. 15 (13-18 [7-24]) cmH₂O, p < 0.001) and two-lung ventilation (9 (7-13 [4-26]) vs. 12 (10-14 [5-26]) cmH₂O, p < 0.001) and a higher oxygenation index during one-lung ventilation (26.7 (20.3-34.4 [6.7-55.9]) vs. 22.7 (16.0-29.3 [8.8-58.9]) kPa, p < 0.001) compared with those allocated to the PEEP₅ group. Despite this, the incidence of postoperative pulmonary complications was similar between groups (PEEP_IND group 54/195 (28%) vs. PEEP₅ group 50/197 (25%), risk ratio 1.09, 95%CI 0.79-1.52, p = 0.60).

Discussion: Electrical impedance tomography-guided individualised positive end-expiratory pressure reduced driving pressures and improved intra-operative oxygenation but did not decrease the incidence of postoperative pulmonary complications in older adults undergoing lung cancer surgery.

Plain language summary

What we did: We studied 400 older people (aged 60 and over) who were having surgery for lung cancer. During their operations, they were put into two groups: one group had their breathing machine set to a pressure chosen specially for them and the other group used the same fixed pressure used for everyone. We then checked how well their lungs worked during surgery and whether they had breathing problems after surgery.

Why did we do it: People often have lung problems after lung cancer surgery, especially older adults. Doctors thought that choosing a breathing pressure that is right for each person might help protect the lungs and stop problems after surgery. We wanted to see if this personalised pressure really made a difference.

What we found: We found that the personalised pressure helped lungs work better during the operation and increased the amount of oxygen in the blood during surgery. However, people in both groups had about the same number of lung problems (such as pneumonia) after surgery. This means that, while personalised breathing pressure helped during the operation, it did not reduce lung problems after surgery in older patients.