Capacity of the Pectoralis Major Muscle May Be a Prognostic Factor for Aspiration Pneumonia

Abstract

Objective: Aspiration pneumonia is thought to be caused by a decline in respiratory and swallowing function. We aimed to clarify whether the pectoralis major muscle and the rectus abdominis muscles are prognostic factors for aspiration pneumonia and to investigate the relationships between these muscles and nutritional status, swallowing function and sarcopenia, Methods: Medical records of 139 Japanese patients hospitalized for aspiration pneumonia between December 2010 and December 2014 were reviewed retrospectively. The volume and thickness of the pectoralis major muscle, the crosssectional area and thickness of the rectus abdominis muscles, and cross-sectional area of the psoas major muscle were measured using computed tomography. Swallowing function, nutritional status, activities of daily living, and prognosis also were evaluated. Results: The volume [Median: (left) 4713.2 mm3 vs. 4232.6 mm3 (right) 4981.7 mm3 vs. 4362.6 mm3 p < 0.05] and thickness [Median: (left) 6.9 mm vs. 4.6 mm (right) 7.3 mm vs. 5.7 mm p < 0.01] of the pectoralis major muscle and thickness of the right rectus abdominis muscles [Median: 7.3 mm vs. 5.8 mm p < 0.05] were significantly larger, while Mini-Nutritional Assessment Short Form (MNA-SF) [Median: 6.0 vs. 4.0 p < 0.01] and Functional Oral Intake Scale (FOIS) [Median: 3 vs. 1 p < 0.01] scores were significantly higher in patients who survived. The volume [Median: (left) 5789.1 mm3 vs. 3706.5 mm3 (right) 5650.3 mm3 vs. 4003.7 mm3 p < 0.01] and thickness [Median: (left) 7.1 mm vs. 5.9 mm p < 0.05] of the pectoralis major muscle and cross-sectional area of the psoas major muscle (left and right) [Median: (left) 500.1 mm2 vs. 432.0 mm2 (right) 563.5 mm2 vs. 446.3 mm2 p < 0.01] were significantly larger, while albumin levels [Median: 3.8 g/dl vs. 3.4g/dl p < 0.01] and MNA-SF [Median: 6.0 vs. 5.0 p < 0.01] and FOIS [Median: 4 vs. 1 p < 0.01] scores were significantly higher in patients with coexisting diseases. Conclusion: The capacity of the pectoralis major muscle may be an independent factor in the prognosis of elderly patients with aspiration pneumonia as a primary disease.