Effect of Positive Expiratory Pressure Therapy on Lung Volumes and Health Outcomes in Adults with Chest Trauma: A Systematic Review and Meta-Analysis.

PEP therapy is a safe intervention with very low-level evidence showing improvements in forced vital capacity, forced expiratory volume in 1 second, respiratory muscle strength, and incidence of pneumonia. It does not improve arterial blood gases, atelectasis, or hospital length of stay. As the evidence is very low level, more rigorous physiological and dose-response studies are required to understand the true impact of PEP on the lungs after chest trauma.