Background: Positive expiratory pressure (PEP) therapy increases lung volumes and clears secretions for respiratory conditions. Following acute chest trauma there is potential for PEP to improve health outcomes, however the efficacy and safety of PEP therapy is not clear.

Aims: To determine the effect of PEP therapy on lung volumes and health outcomes, and confirm safety, following acute chest trauma.

Methods: A search was conducted across six healthcare databases from inception to 2019. Randomised controlled trials comparing PEP therapy with usual care or other physiotherapy interventions in adults with any form of chest trauma were included. Outcomes of lung volumes, incidence of pneumonia, hospital length of stay and number of adverse events were meta-analysed. The Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to downgrade the evidence.

Results: Eleven studies (n=661) of fair methodological quality were included. Devices and dosages varied among the studies. There is very low-level evidence that PEP improves forced vital capacity (SMD -0.50, 95% CI -0.79 to -0.21), forced expiratory volume at 1 second (SMD -0.38, 95% CI: -0.62 to -0.13), and reduces the incidence of pneumonia (RR 0.16, 95%C CI 0.03 to 0.85). No significant adverse events were reported.

Conclusion: PEP therapy is a safe intervention that may be used to improve lung volumes and reduce the incidence of pneumonia in patients with chest trauma. As the evidence is very low level, routine use of PEP therapy cannot yet be recommended.