The effect of Preoperative threshold inspiratory muscle training in adults undergoing cardiac surgery on postoperative hospital stay: a systematic review

Background Systematic reviews have reported benefits of preoperative inspiratory muscle training in adults undergoing cardiac surgery, however there have been inconsistencies with the devices used. Threshold devices generate a constant inspiratory load independent of respiratory rate. Objective To assess the effect of preoperative inspiratory muscle training using threshold devices in adults undergoing cardiac surgery. Methods A literature search was conducted across five electronic databases. Seven randomized controlled trials met the inclusion criteria and were critically appraised. The primary outcome was length of hospital stay. Secondary outcomes included postoperative pulmonary complications, quality of life and mortality. Results Seven eligible randomized controlled trials were identified with a total of 642 participants. One study was a post hoc analysis of one of the included studies. Three out of five studies reported a decrease in length of postoperative hospital stay (p < 0.05). A significant reduction in postoperative pulmonary complications was reported by three studies (p < 0.05). There were concerns with bias across all papers. Conclusions Preoperative threshold inspiratory muscle training has potential to reduce postoperative length of hospital stay and pulmonary complications after cardiac surgery. The evidence on quality of life and mortality is inconclusive. The overall evidence for these conclusions may be influenced by bias.