Effect of post-extubation high-flow nasal cannula combined with respiratory training versus conventional oxygen therapy on postoperative pulmonary complications in patients after major abdominal surgery: Protocol for a single-centre randomised controlled trial

Background: Nearly 234 million patients undergo surgery each year, and 1.3 million develop complications. The risk of postoperative pulmonary complications (PPCs) remains high, especially in major upper abdominal surgery. The occurrence of PPCs seriously affects the outcomes of surgical patients, and the risk of death is significantly increased. This could have a serious impact on the prognosis of patients if no effective prevention or timely intervention is carried out. High-flow nasal cannula (HFNC) is increasingly used in postoperative patients and is confirmed to be as effective as noninvasive ventilation (NIV) in preventing postoperative hypoxaemia and respiratory failure. In our clinical study, we observed faster recovery with combined HFNC and respiratory training (using PEP Acapella Choice) in patients with postoperative atelectasis. These two interventions have a theoretical benefit in the prevention of PPCs, but no relevant prospective randomised controlled studies have been conducted. Could HFNC combined with respiratory training reduce the incidence of PPCs compared to conventional oxygen therapy (COT) in postoperative patients? Could these combined interventions reduce mortality or improve the long-term prognosis? The answers to these questions remain unknown. In this randomised controlled trial, we hypothesise that HFNC combined with respiratory training will reduce the incidence of PPCs and mortality and improve the long-term prognosis in this cohort. Methods This is a randomised controlled single-centre trial. A total of 328 patients who undergo major abdominal surgeries will be included. Subjects will be randomised to receive HFNC combined with Acapella or COT alone immediately after extubation. Our primary endpoint is the incidence of PPCs within 7 days, and the secondary outcome measures include 28-day mortality, reintubation, length of hospital stay, and all-cause mortality within 1 year. Discussion This trial would help provide evidence of the preferred effect of HFNC combined with Acapella on COT in patients after major abdominal surgery. The objective of this study is to determine the optimal choice for improving the prognosis of patients undergoing surgery. Trial registration: ChiCTR2100047146. Registered on 8 June 2021. Retrospectively registered.