Association of Preoperative Spirometry with Cardiopulmonary Exercise Capacity and Postoperative Outcomes in Surgical Patients

Spirometry and cardiopulmonary exercise testing (CPET) are specialized investigations which help stratify risk for postoperative complications. Prior research has found inconsistent associations between forced expiratory volume in 1 second (FEV1), and the ratio of FEV1 to forced vital capacity (FVC) from spirometry with postoperative complications. This thesis examines the hypothesis that FEV1 and FEV1/FVC are associated with peak oxygen uptake (VO2 peak) and ventilatory efficiency from CPET, which confound the association between FEV1 and outcomes. In a cohort of patients undergoing elective inpatient surgery, FEV1 exhibited a linear association of moderate magnitude with VO2 peak. The association of FEV1 with ventilatory efficiency, and FEV1/FVC with VO2 peak and ventilatory efficiency were weak. Following adjustment for clinical risk factors and VO2 peak or ventilatory efficiency, FEV1 was not associated with postoperative outcomes. Thus, previously observed associations between FEV1 and respiratory complications may be partly explained by confounding related to cardiopulmonary fitness.M.Sc