question: PURPOSE Up to 30% of patients undergoing abdominal surgery suffer from postoperative pulmonary complications. The purpose of this systematic review and meta-analyses was to investigate whether postoperative respiratory interventions and mobilization interventions compared with usual care can prevent postoperative complications following abdominal surgery. METHODS The review was conducted in line with PRISMA and GRADE guidelines. MEDLINE, Embase, and PEDRO were searched for randomized controlled trials and observational studies comparing postoperative respiratory interventions and mobilization interventions with usual care in patients undergoing abdominal surgery. Meta-analyses with trial sequential analysis on the outcome pulmonary complications were performed. Review registration: PROSPERO (identifier: CRD42019133629) RESULTS: Pulmonary complications were addressed in 25 studies containing 2068 patients. Twenty-three studies were included in the meta-analyses. Patients predominantly underwent open elective upper abdominal surgery. Postoperative respiratory interventions consisted of expiratory resistance modalities (CPAP, EPAP, BiPAP, NIV), assisted inspiratory flow modalities (IPPB, IPAP), patient-operated ventilation modalities (spirometry, PEP), and structured breathing exercises. Meta-analyses found that ventilation with high expiratory resistance (CPAP, EPAP, BiPAP, NIV) reduced the risk of pulmonary complications with OR 0.42 (95% CI 0.18-0.97, p = 0.04, I2 = 0%) compared with usual care, however, the trial sequential analysis revealed that the required information size was not met. Neither postoperative assisted inspiratory flow therapy, patient-operated ventilation modalities, nor breathing exercises reduced the risk of pulmonary complications. CONCLUSION The use of postoperative expiratory resistance modalities (CPAP, EPAP, BiPAP, NIV) after abdominal surgery might prevent pulmonary complications and it seems the preventive abilities were largely driven by postoperative treatment with CPAP.