Relation Between Low Pulmonary Function and Skeletal Muscle Index in Burn Patients with Major Burn Injury and Smoke Inhalation: A Retrospective Study

This report is to evaluate the relation between pulmonary function, respiratory muscle strength, and skeletal muscle index (SMI) in patients with major burn injury and smoke inhalation. A total of 54 inhalation burn patients were analyzed. Appendicular skeletal muscle mass (ASM) is a sum of the muscle mass of both arms and legs. SMI is adjusting for body size using body mass index (ASM/BMI). Spirometry was performed to evaluate pulmonary function. Pulmonary function tests included peak cough flow (PCF), forced vital capacity (FVC), 1-s forced expiratory volume (FEV1), forced expiratory flow rate between 25 and 75% of the FVC (FEF 25–75), FEV1/FVC ratio expressed as a percentage (FEV1/FVC %), peak expiratory flow (PEF), and maximum voluntary ventilation. Expiratory and inspiratory muscle strengths were measured. The relations between pulmonary function, respiratory muscle strength, and SMI were investigated. SMI showed significant correlations with PCF (r = 0.34 and P = 0.02), FVC (r = 0.55 and P < 0.001), FEV1 (r = 0.45 and P = 0.001), and PEF (r = 0.35 and P = 0.01). In multiple regression analysis including age, TBSA, duration of mechanical ventilation, and postburn days studied, SMI was significantly related to FVC, PCF, FEV1, FEV1/FVC, and PEF (P < 0.001, P = 0.02, P = 0.001, P = 0.04, and P = 0.03). Pulmonary function tests are significantly related to SMI in patients with major burn injury and smoke inhalation. Intensive treatment on muscle wasting in patients with burn injury has been proven to be important for improving pulmonary functions.