Journal Article

57 Is single breath count a reliable surrogate marker for forced vital capacity in myasthenia gravis?

Aslanyan, Aram, Boardman, Jeremy, B Lilleker James, Mohanraj, Rajiv, Sussman, Jon, C Dodd Katherine, Glass, Hannah, Rizvi, Khaizer

2025

Overview

Bedside forced vital capacity (FVC) monitoring is the gold standard in detecting impending respiratory failure in patients with neuromuscular disease. However, bedside spirometry is often unavailable, especially in resource-limited settings, and facial muscle weakness can lead to unreliable measurements. In these settings the single breath count (SBC) is a potential alternative as it does not require specialised equipment nor is it affected by facial muscle weakness.However, uncertainties remain about its reliability in assessing patients with neuromuscular diseases such as myasthenia gravis in clinical practice.We compared SBC and FVC in 43 healthy adult volunteers and in 15 patients with seropositive myasthenia gravis in the outpatient setting. The myasthenic cohort, who were all anti-acetylcholine receptor antibody positive, had varying degrees of neuromuscular (bulbar and limb) weakness. Using linear regression, we showed a positive correlation between FVC and SBC in both healthy volunteers (R = 0.73, p<0.001) and myasthenia gravis patients (R= 0.59. P< 0.002). These results provide further evidence that SBC is a reliable and reproducible alternative FVC in settings where spirometry is [e-mail]

• Publisher: BMJ Publishing Group LTD
• Subject: Myasthenia gravis / Spirometry