Impact of drains positioning on pulmonary function after coronary artery bypass grafting: an observational study

INTRODUCTION: Coronary artery bypass grafting (CABG) is a procedure associated with a decline in pulmonary function. Among the main causes is the presence of the drain that is usually positioned in the intercostal or subxiphoid region. OBJECTIVE: To measure the interference of drains positioning on pulmonary function in patients undergoing CABG. METHODS: Observational study that assessed preoperative pulmonary function through vital capacity (VC), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and peak expiratory flow (PEF). These variables were evaluated in three different moments: in the presence of two drains, when removing one, and after removing all drains. RESULTS: We evaluated 45 patients with a mean age of 62 ± 7 years with male prevalence of 29 (64%) individuals. The insertion of drains caused a decline in pulmonary function after surgery by reducing MIP by 48%, MEP by 11%, VC by 39%, and PEF by 6%. CONCLUSION: This study has demonstrated that drains positioning after CABG surgery may produce weakness of the respiratory muscles, change ventilatory mechanics, and impair normal pulmonary function postoperatively.