RESPIRATORY-FUNCTION AFTER CARDIAC-SURGERY

Study Objective: Cardiac surgery is complicated by decreased postopera tive respiratory muscle strength and spirometry with accompanying incr eased atelectasis. The specific respiratory symptoms attributable to t hese physiologic changes are unknown, and this study looked at the sym ptoms and underlying physiology.Design: Convenience sampling of observ ational cohort. Setting: Tertiary care university hospital. Patients: One hundred thirty-eight patients undergoing elective surgery were enr olled. Interventions: Changes from admission to 8-week postoperative v alues in atelectasis, pleural effusions, spirometry (forced vital capa city and forced expiratory volume in one second), and respiratory musc le strength (negative inspiratory pressure) were measured. These physi ologic changes were compared with changes in respiratory symptoms of c ough, wheeze, phlegm, and dyspnea on walking up a slight hill noted fr om admission to 8-week follow-up by stepward logistic regression. Meas urements and Results: Spirometry and negative inspiratory pressure dec reased and atelectasis increased from admission to discharge. These di sturbances had only incompletely resolved at 8-week follow up. Some pa tients reported fewer symptoms of cough (11%), phlegm (9%), wheeze (35 %), and dyspnea (46%) at 8 weeks follow-up. Other patients reported in creased symptoms of cough (15%), phlegm (10%), wheeze (6%), and dyspne a (4%) at 8 weeks follow-up. Residual atelectasis at 8 weeks was predi ctive of fewer symptoms of dyspnea (odds ratio [OR] 0.335, p = 0.199; 95% confidence interval [CI] 0.188, 0.597), increased symptoms of dysp nea (OR 855, p = 0.006; 95% CI 6.6, 11052), and increased symptoms of cough (OR 260, p = 0.023; 95% CI 2.13, 31829). Negative inspiratory pr essure at 8 weeks was predictive of fewer symptoms of dyspnea (OR 1.05 , p = 0.032; 95% CI 1.02, 1.09) and increased symptoms of wheeze (OR 0 .7, p = 0.45; 95% CI 0.533, 0999). Forced vital capacity at 8 weeks wa s predictive of increased symptoms of wheeze (OR 0.005; p = 0.015; 95% CI 0.0060, 0.775). Conclusions: Postoperative changes in respiratory muscle strength and spirometry can persist up to at least 8 weeks post operatively. Many patients report a change in respiratory symptoms of cough, phlegm, dyspnea, or wheeze. The change in respiratory symptoms at 8 weeks is correlated with residual respiratory muscle weakness, de crease in spirometry, and residual atelectasis. Copyright (C) 1996 by W.B. Saunders Company