Lung function measurements in young children with spinal muscle atrophy; across sectional survey on the effect of position and bracing

Background - Spinal muscular atrophy (SIMA) affects respiratory muscles, wh ich in addition to progressive scoliosis leads to respiratory impairment. C hildren with developing scoliosis are usually treated with spinal bracing t o delay the progress. Aims - To assess the impact of body position and application of spinal brac ing on lung function during tidal breathing in children with SMA. Methods - Lung function was determined by tidal flow volume loops and passi ve respiratory mechanics (single breath occlusion technique) in all eight c hildren in southern Norway with SMA type I and II, in both the sitting and supine position. Additional measurements were performed with and without br acing in five children. Muscle strength was assessed by the Brooks scale. Results - Tidal expiratory volume (V,) and compliance of the respiratory sy stem (CRS) tended to be higher in the sitting compared to the supine positi on, but this was not statistically significant. However, applying bracing i n the sitting position significantly reduced V,. The highest values of CRS and V, were found in the sitting position without bracing. Conclusion - Impairment of tidal respiration must be considered when applyi ng spinal bracing in very young children developing scoliosis with SMA.