Prevalence and Implications of Abnormal Respiratory Patterns in Cardiac Surgery: A Prospective Cohort Study.

OBJECTIVE: To investigate the prevalence and impact of abnormal respiratory patterns in cardiac surgery patients.

DESIGN: Prospective cohort study.

SETTING: Tertiary hospital.

PARTICIPANTS: Patients scheduled for elective coronary artery bypass graft surgery.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Pulmonary function tests were performed in 454 patients before surgery. Abnormal respiratory patterns were defined as follows: obstructive (forced expiratory volume in 1 s [FEV1 ]/forced vital capacity [FVC]<0.70), restrictive (FEV1 /FVC≥0.70 and FVC<80% of predicted), and mixed (FEV1 /FVC<0.70 and both FEV1 and FVC<80% of predicted). Of the 31 patients with a history of chronic obstructive pulmonary disease, no abnormal respiratory pattern was confirmed in 5. Of the 423 patients without a history of lung disease, the authors newly identified 57 obstructive, 46 restrictive, and 4 mixed patterns. Therefore, lung disease was reclassified in 24.7% of cases. Independent predictors of obstructive pattern were age, male sex, history of smoking, and chronic obstructive pulmonary disease. Obstructive lung disease was associated with 16 hours or longer ventilation. A reduced FEV1 was associated with a likelihood of atrial fibrillation (1-L decrement, odds ratio: 1.38, 95% confidence interval: 1.01-to-1.90, p = 0.04) and hospitalization time (regression coefficient: 1.23, 95% confidence interval: 0.54-to-1.91, p<0.001).

CONCLUSIONS: Abnormal respiratory patterns are common and often underdiagnosed in the cardiac surgery setting. Pulmonary function tests help reveal patients at risk of complications and may provide an opportunity for intervention.