Equivalence study of vital capacity in children with neuromuscular disorders

Abstract

Introduction/Aim: Vital capacity is a valuable predictor of susceptibility to infection and need for respiratory support in children with neuromuscular disorders (NMD). It is determined by inspiratory muscle strength, lung and chest wall compliance. It can be reliably measured in most weak subjects by using a slow manoeuvre. Forced manoeuvres are routinely performed on NMD patients. This equivalent study aimed to determine if significant differences in measurement of lung volumes-by forced (FVC) or slow (SVC) manoeuvres exist. Patient preference was also assessed. Method: Subjects (n = 45) were prospectively recruited sequentially from neuromuscular and sleep outpatient appointments. The study was powered at 0.8 with significance set at 0.05, a clinically significant variation was considered 0.2 L for the sample size calculation. Standard clinic spirometry (forced manoeuvre) was performed. The slow manoeuvre was then performed after a period of rest in the same session and subjects were asked their preference. Results: A paired t-test compared FVC and SVC measures (litres and z-score). Mean (SD), 95% CI and p-values are reported in Table 1. No statistically significant difference was found between the measures. A Pearson's χ2 test compared patient's technique preference (FVC, SVC, no preference) and VC result. We found statistically significant differences in technique preferences between patients with a normal versus abnormal VC. Regardless of VC results, subjects tended to prefer SVC. Conclusion: The FVC and SVC measures are equivalent. The paediatric neuromuscular population could follow their preference in performing either the forced or slow manoeuvre. (Table Presented).L6377946242022-04-25 <br />