Preoperative pulmonary function in all comers for cardiac surgery predicts mortality†

Objectives: Although reduced lung function and chronic obstructive pulmonary disease (COPD) is associated with higher risk of death following cardiac surgery, preoperative spirometry is not performed routinely. The aim of this study was to investigate the relationship between preoperative lung function and postoperative complications in all comers for cardiac surgery irrespective of smoking or COPD history.

Methods: Preoperative spirometry was performed in elective adult cardiac surgery patients. Airflow obstruction was defined as the ratio of forced expiratory volume in 1 s (FEV1)/forced vital capacity ratio below the lower limit of normal (LLN) and reduced forced ventilatory capacity defined as FEV1 <LLN.

Results: A history of COPD was reported by 132 (19%) patients; however, only 74 (56%) had spirometry-verified airflow obstruction. Conversely, 64 (12%) of the 551 patients not reporting a history of COPD had spirometry-verified airflow obstruction. The probability of death was significantly higher in patients with airflow obstruction (8.8% vs 4.5%, P = 0.04) and in patients with a FEV1 <LLN (8.7% vs 3.7%, P = 0.007). In the multivariate analysis were age [hazard ratio (HR) 1.6, 95% confidence interval (CI) 1.0-2.5; P = 0.04], prolonged cardiopulmonary bypass time (HR 1.2, 95% CI 1.02-1.3; P = 0.03), reduced kidney function (HR 2.5, 95% CI 1.2-5.6; P = 0.02) and FEV1 <LLN (HR 2.4, 95% CI 1.1-5.2; P = 0.03) all independently associated with an increased risk of death.

Conclusions: Preoperative spirometry reclassified 18% of the patients. A reduced FEV1 independently doubled the risk of death. Inclusion of preoperative spirometry in routine screening of cardiac surgical patients may improve risk prediction and identify high-risk patients.

Clinical trial registration number: NCT01614951 (ClinicalTrials.gov).