Association of VO₂max With Postoperative Respiratory Complications in Patients Undergoing Lung Resection Surgery: An Exploratory Study.

INTRODUCTION: Preoperative risk assessment is important in patients undergoing lung resection, as postoperative respiratory complications and early mortality remain significant concerns. Cardiopulmonary exercise testing provides an integrated assessment of functional capacity, and maximum oxygen consumption (VO₂max) reflects overall cardiopulmonary reserve. It may therefore help identify patients at increased perioperative risk. OBJECTIVE: The primary aim of the study was to predict early postoperative respiratory complications using preoperative VO₂max in subjects undergoing lung resection. The secondary aim was to assess 90-day postoperative mortality. METHODOLOGY: This prospective observational study was conducted in the department of pulmonary medicine, in collaboration with the department of cardiothoracic and vascular surgery and surgical oncology at a tertiary care center from January 2024 to November 2025. A total of 46 subjects were included for evaluation for lung resection. All subjects underwent preoperative spirometry and cardiopulmonary exercise testing. Postoperative respiratory complications were assessed during the early postoperative period, and mortality was recorded till 90 days. RESULTS: The median preoperative VO₂max was 8.91 mL/kg/minute in the postoperative complication group compared with 16.34 mL/kg/minute in subjects without complications (P = 0.002). Postoperative respiratory complications (pneumonia with respiratory failure and pleural effusion) occurred in 4 (8.7%) of the 46 subjects. The 90-day postoperative mortality was 3 (6.5%) of the 46 subjects. Subjects who died had a median VO₂max of 7.8 mL/kg/minute, whereas survivors had a median value of 16.21 mL/kg/minute (P = 0.007). CONCLUSIONS: Lower preoperative VO₂max was observed in subjects who developed early (within 14 days) postoperative respiratory complications and in those who died within 90 days after lung resection. These findings suggest that preoperative VO₂max may help predict postoperative respiratory complications and mortality within 90 days.