Routine postoperative noninvasive respiratory support and pneumonia after elective surgery: a systematic review and meta-analysis of randomised trials

Background: Postoperative pulmonary complications, including pneumonia, are a substantial cause of morbidity. We hypothesised that routine noninvasive respiratory support was associated with a lower incidence of pneumonia after surgery.

Methods: Systematic review and meta-analysis of RCTs comparing the routine use of continuous positive airway pressure (CPAP), noninvasive ventilation (NIV), or high-flow nasal oxygen (HFNO) against standard postoperative care in the adult population. We searched MEDLINE (PubMed), EMBASE, and CENTRAL from the start of indexing to July 27, 2021. Articles were reviewed and data extracted in duplicate, with discrepancies resolved by a senior investigator. The primary outcome was pneumonia, and the secondary outcome was postoperative pulmonary complications. We calculated risk difference (RD) with 95% confidence intervals using DerSimonian and Laird random effects models. We assessed risk of bias using the Cochrane risk of bias tool.

Results: From 18 513 records, we included 38 trials consisting of 9782 patients. Pneumonia occurred in 214/4403 (4.9%) patients receiving noninvasive respiratory support compared with 216/3937 (5.5%) receiving standard care (RD -0.01 [95% confidence interval: -0.02 to 0.00]; I²=8%; P=0.23). Postoperative pulmonary complications occurred in 393/1379 (28%) patients receiving noninvasive respiratory support compared with 280/902 (31%) receiving standard care (RD -0.11 [-0.23 to 0.01]; I²=79%; P=0.07). Subgroup analyses did not identify a benefit of CPAP, NIV, or HFNO in preventing pneumonia. Tests for publication bias suggest six unreported trials.

Conclusion: The results of this evidence synthesis do not support the routine use of postoperative CPAP, NIV, or HFNO to prevent pneumonia after surgery in adults.

Clinical trial registration: PROSPERO: CRD42019156741.