Quantity and quality of antigravity muscles in patients undergoing living-donor lobar lung transplantation: 1-year longitudinal analysis using chest computed tomography images

BACKGROUND: Skeletal muscle dysfunction is a common feature in patients with severe lung diseases. Although lung transplantation aims to save these patients, the surgical procedure and disuse may cause additional deterioration and prolonged functional disability. We investigated the postoperative course of antigravity muscle condition in terms of quantity and quality using chest computed tomography. METHODS: 35 consecutive patients were investigated for 12 months after living-donor lobar lung transplantation (LDLLT). The erector spinae muscles (ESMs), which are antigravity muscles, were evaluated, and the cross-sectional area (ESM(CSA)) and mean attenuation (ESM(CT)) were analysed to determine the quantity and quality of ESMs. Functional capacity was evaluated by the 6-min walk distance (6MWD). Age-matched living donors with lower lobectomy were evaluated as controls. RESULTS: Recipient and donor ESM(CSA) values temporarily decreased at 3 months and recovered by 12 months post-operatively. The ESM(CSA) of recipients, but not that of donors, surpassed baseline values by 12 months post-operatively. Increased ESM(CSA) (ratio to baseline ≥1) may occur at 12 months in patients with a high baseline ESM(CT). Although the recipient ESM(CT) may continuously decrease for 12 months, the ESM(CT) is a major determinant, in addition to lung function, of the postoperative 6MWD at both 3 and 12 months. CONCLUSION: The quantity of ESMs may increase within 12 months after LDLLT in recipients with better muscle quality at baseline. The quality of ESMs is also important for physical performance; therefore, further approaches to prevent deterioration in muscle quality are required.