Height is fundamental to assessing growth and nutrition, calculating body surface area, and predicting pulmonary function in childhood. Its measurement is hindered by muscle weakness, joint, or spinal deformity. Arm span has been used as a substitute, but is inaccurate. The objective of the study was to identify a limb measurement that precisely and reproducibly predicts height in childhood. Males (n=1144) and females (n=1199), aged 5 years 4 months to 19 years 7 months, without disability were recruited from Melbourne schools. Height, arm span, ulna, forearm, tibia, and lower leg lengths were measured with a Harpenden stadiometer and anthropometer. Prediction equations for height based on ulna length (U) and age in years (A) were developed using linear regression. Ulna centile charts were developed by the LMS method. For males, height (cm)=4.605U+1.308A+28.003 (R2=0.96); for females, height (cm)=4.459U+1.315A+31.485 (R2=0.94). Intra- and inter-observer variability was 0.41% and 0.61% relative to the mean, respectively. Height prediction equations from tibia, forearm, and lower leg length were calculated. We show that ulna measurement is reproducible and precisely predicts height in school-age children. It appears to be superior to arm span measurement when neuromuscular weakness, joint, or spinal deformity exists. Ulna growth charts should facilitate growth assessment.

Spirometry is used to monitor respiratory progress in children with Duchenne muscular dystrophy (DMD). Mucociliary clearance depends on cough strength, which can be measured by peak cough flow (PCF). It is not routinely measured in most centers. When the PCF falls below 270 l/min, mucociliary clearance is likely to be impaired during viral illnesses, and techniques to assist mucociliary clearance should be taught. There is no known association between spirometry and PCF. Our aim was to assess if PCF relates to spirometry measures, and if spirometry can be used to predict when the PCF <270 l/min. Children with DMD aged 6-19 years were recruited. Spirometry was performed with a Jaeger Masterscope with version 4.60 software. PCF was performed with a Wright peak flow meter. Data were collected into an Access '97 database, and statistics were performed with Stata 7.0. The association between PCF and spirometry was defined with linear regression. Logistic regression was used to predict the probability that the PCF would be <270 l/min for any given forced vital capacity (FVC) or forced expired volume in 1 sec (FEV1). The risk ratios for PCF <270 l/min were calculated for the spirometry parameters. PCF is associated with FVC (R2, 0.72) and FEV1 (R2, 0.69). The likelihood of PCF <270 l/min rises when FVC <2.l and FEV1 <2.l/sec. The risk ratio for PCF <270 l/min when FVC <2.1 l is 4.80 (1.72-13.40) and when FEV1 <2.1 l/sec is 3.94 (1.43-10.85). In children with DMD, PCF should be measured when FVC <2.1 l or FEV1 <2.1 l/sec, so that techniques to assist with mucociliary clearance can be effectively used.

Pulmonary function is important in neuromuscular weakness. In children, height determines normal values. Height measurement is unreliable when neuromuscular weakness or spinal deformity is present. The aim of this study was to accurately predict pulmonary function from a limb segment measurement that is precise and reproducible. Normal males (n = 1,144) and females (n = 1,199), 5.3 to 19.6 years old, were recruited from Melbourne schools. Height, weight, ulna, forearm, tibia, and lower leg lengths were measured using a Harpenden stadiometer and calipers, and electronic scales. Three maximal expiratory maneuvers were performed. Limb measurements were highly reproducible. Linear regression on log-transformed FEV1 and FVC was used to develop prediction equations from limb measurements and age. In males FEV1 = exp (0.071 x U + 0.046 x A - 1.269), r2 = 0.86; FVC = exp (0.77 x U + 0.041 x A - 1.285), r2 = 0.86 and in females FEV1 = exp (0.072 x U + 0.041 x A - 1.272), r2 = 0.84; FVC = exp (0.078 x U + 0.037 x A - 1.315), r2 = 0.83 (U refers to ulna length and A refers to age). Precision is similar to equations using height. Ulna measurement is accessible in wheelchair-bound children. Using ulna length to predict pulmonary function should facilitate respiratory assessment in children whose height is difficult to measure.

IntroductionNusinersen is used in spinal muscular atrophy (SMA) to improve peripheral muscle function; however, respiratory effects are largely unknown.AimTo assess the effects of nusinersen on respiratory function in paediatric SMA during first year of treatment.MethodsA prospective observational study in paediatric patients with SMA who began receiving nusinersen in Queensland, Australia, from June 2018 to December 2019. Outcomes assessed were the age-appropriate respiratory investigations: spirometry, oscillometry, sniff nasal inspiratory pressure, mean inspiratory pressure, mean expiratory pressure, lung clearance index, as well as polysomnography (PSG) and muscle function testing. Lung function was collected retrospectively for up to 2 years prior to nusinersen initiation. Change in lung function was assessed using mixed effects linear regression models, while PSG and muscle function were compared using the Wilcoxon signed-rank test.ResultsTwenty-eight patients (15 male, aged 0.08–18.58 years) were enrolled: type 1 (n=7); type 2 (n=12); type 3 (n=9). The annual rate of decline in FVC z-score prior to nusinersen initiation was −0.58 (95% CI −0.75 to −0.41), and post initiation was −0.25 (95% CI −0.46 to −0.03), with a significant difference in rate of decline (0.33 (95% CI 0.02 to 0.66) (p=0.04)). Most lung function measures were largely unchanged in the year post nusinersen initiation. The total Apnoea–Hypopnoea Index (AHI) was reduced from a median of 5.5 events/hour (IQR 2.1–10.1) at initiation to 2.7 events/hour (IQR 0.7–5.3) after 1 year (p=0.02). All SMA type 1% and 75% of SMA types 2 and 3 had pre-defined peripheral muscle response to nusinersen.ConclusionThe first year of nusinersen treatment saw reduced lung function decline (especially in type 2) and improvement in AHI.

Height is fundamental to assessing growth and nutrition, calculating body surface area, and predicting pulmonary function in childhood. Its measurement is hindered by muscle weakness, joint, or spinal deformity. Arm span has been used as a substitute, but is inaccurate. The objective of the study was to identify a limb measurement that precisely and reproducibly predicts height in childhood. Males (n=1144) and females (n=1199), aged 5 years 4 months to 19 years 7 months, without disability were recruited from Melbourne schools. Height, arm span, ulna, forearm, tibia, and lower leg lengths were measured with a Harpenden stadiometer and anthropometer. Prediction equations for height based on ulna length (U) and age in years (A) were developed using linear regression. Ulna centile charts were developed by the LMS method. For males, height (cm)=4.605U+1.308A+28.003 (R2=0.96); for females, height (cm)=4.459U+1.315A+31.485 (R2=0.94). Intra‐ and inter‐observer variability was 0.41% and 0.61% relative to the mean, respectively. Height prediction equations from tibia, forearm, and lower leg length were calculated. We show that ulna measurement is reproducible and precisely predicts height in school‐age children. It appears to be superior to arm span measurement when neuromuscular weakness, joint, or spinal deformity exists. Ulna growth charts should facilitate growth assessment.

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BackgroundSpinal muscular atrophy (SMA) causes progressive respiratory muscle weakness but respiratory function (RF) in those using noninvasive ventilation (NIV) is not well described.ObjectiveTo describe RF in childhood SMA and assess differences between those using and not using NIV.MethodsA cross‐sectional study of childhood SMA assessed polysomnography (PSG), spirometry, forced oscillation technique (FOT), lung clearance index (LCI), sniff nasal inspiratory pressures, peak cough flow, maximal inspiratory and expiratory pressure, and NIV use and indication.ResultsTwenty‐five children (median age [interquartile range], 8.96 [5.63] years; 10 F) with SMA 1 (n = 3), 2 (n = 15), and 3 (n = 7) were recruited. Spirometry and FOT testing was feasible in children as young as 3 years. Ten (40%) required NIV, 5 for sleep‐disordered breathing (SDB), and 5 initiated during lower respiratory tract infection (LRTI). Children requiring NIV were older (median, 10.52 vs 5.67 years; P < .02) with more abnormal forced vital capacity (FVC) z‐score (−5.70 vs −1.39, P < .02), Rsr8 z‐score (1.97 vs 0.50, P = .04), and LCI (8.84 vs 7.34, P = .01). Two had normal RF and SDB. For FVC z‐score less than −2.5 and LCI greater than 7.5, the odds ratio for NIV was 10.70 (95% confidence interval [CI], 1.39‐82.03) and 2 (95% CI, 0.40‐10.31), respectively. All children with LCI greater than 8 used NIV. FVC z‐score and LCI are associated with maximum transcutaneous carbon dioxide on PSG (r = 0.43, P < .001).ConclusionNIV is common in SMA. Normal RF does not exclude SDB. Children with more abnormal FVC and LCI should be considered at risk of starting NIV during/following an LRTI.