Respiratory sarcopenia: A position paper by four professional organizations

Abstract

We defined respiratory sarcopenia as a coexistence of respiratory muscle weakness and decreased respiratory muscle mass. Although respiratory muscle function is indispensable for life support, its evaluation has not been included in the regular assessment of respiratory function or adequately evaluated in clinical practice. Considering this situation, we prepared a position paper outlining basic knowledge, diagnostic and assessment methods, mechanisms, involvement in respiratory diseases, intervention and treatment methods, and future perspectives on respiratory sarcopenia, and summarized the current consensus on respiratory sarcopenia. Respiratory sarcopenia is diagnosed when respiratory muscle weakness and decreased respiratory muscle mass are observed. If respiratory muscle mass is difficult to measure, we can use appendicular skeletal muscle mass as a surrogate. Probable respiratory sarcopenia is defined when respiratory muscle weakness and decreased appendicular skeletal muscle mass are observed. If only respiratory muscle strength is decreased without a decrease in respiratory function, the patient is diagnosed with possible respiratory sarcopenia. Respiratory muscle strength is assessed using maximum inspiratory pressure and maximum expiratory pressure. Ultrasonography and computed tomography are commonly used to assess respiratory muscle mass; however, there are insufficient data to propose the cutoff values for defining decreased respiratory muscle mass. It was jointly prepared by the representative authors and authorized by the Japanese Society for Respiratory Care and Rehabilitation, Japanese Association on Sarcopenia and Frailty, Japanese Society of Respiratory Physical Therapy and Japanese Association of Rehabilitation Nutrition. Geriatr Gerontol Int 2023; 23: 5-15.

Keywords: diaphragm; muscle; rehabilitation; respiration; sarcopenia.

Figure 1

Interaction of whole‐body sarcopenia, respiratory sarcopenia and respiratory disease. COPD is shown as a typical example of respiratory disease. COPD causes whole‐body sarcopenia and respiratory sarcopenia. Whole‐body sarcopenia causes respiratory sarcopenia. Whether respiratory sarcopenia causes whole‐body sarcopenia is hypothetical (dashed arrow). Aging causes whole‐body sarcopenia and respiratory sarcopenia. COPD causes undernutrition and inactivity. Malnutrition and low activity are associated with whole‐body sarcopenia and respiratory sarcopenia. Smoking causes COPD and whole‐body sarcopenia. Whether smoking causes, respiratory sarcopenia is hypothetical (dashed arrow). Whole‐body and respiratory sarcopenia affect the clinical course and symptoms of COPD. In particular, respiratory sarcopenia may enhance respiratory dysfunction. However, whether whole‐body sarcopenia and respiratory sarcopenia directory affect COPD pathologically is hypothetical (dashed arrow). COPD, chronic obstructive pulmonary disease.

Figure 2

Diagnostic algorithm for respiratory sarcopenia. Diagnosis of “respiratory sarcopenia” is made when low respiratory muscle mass is confirmed in addition to low respiratory muscle strength. If respiratory muscle mass cannot be measured, the diagnosis of “probable respiratory sarcopenia” is made when a low appendicular skeletal muscle mass is confirmed. European Working Group on Sarcopenia in Older People 2, Asian Working Group for Sarcopenia 2019, or other cutoff values can be used to determine the presence of low appendicular skeletal muscle mass. Diagnosis of “possible respiratory sarcopenia” is made when only low respiratory muscle strength is observed without low respiratory function. CT, computed tomography; MEP, maximal expiratory pressure; MIP, maximal inspiratory pressure; US, ultrasound.