Abstract
Background: Cardiovascular diseases are the main cause of mortality and morbidity in Portugal, with coronary artery bypass grafting (CABG) being one of the most performed surgeries in cardiothoracic centers. After cardiac surgery, patients often experience a decrease in physical capacity, which results in an increased risk of mortality or hospitalization expenditures. The objective of this systematic review was to characterize changes in respiratory function in patients undergoing CABG. Methods: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Web of Science, Pubmed, SCOPUS, and Sport Discus were searched using a predefined research strategy to identify relevant original studies published until August 2025. To be included, studies must have assessed adult patients submitted to CABG who evaluated the respiratory function before and after cardiac surgery. Studies that reported other types of cardiac surgery were excluded. The Risk of Bias in Non-randomized Studies-of-Exposure and the Cochrane risk-of-bias tool for randomized trials were used to analyze the risk of bias of the selected studies. Results: After screening 1184 potential articles, six studies met the inclusion criteria. The studies included participants who underwent CABG (n = 324), with a mean age ranging from 54.05 ± 13.6 to 67 ± 10 years. Conclusions: All included studies reported significant postoperative reductions in respiratory function following CABG, including forced vital capacity, forced expiratory volume in one second, maximal inspiratory pressure, and maximal expiratory pressure. Although these findings consistently indicate a decline in pulmonary function, the limited number of available studies limits the strength of the conclusions. This systematic review suggests that monitoring respiratory impairments after CABG may be clinically relevant to improve health-related quality of life.