Assessment of respiratory muscles and motor function in children with SMA treated by nusinersen.

INTRODUCTION: Nusinersen is associated with an improvement in motor function in children with spinal muscular atrophy (SMA) but data on respiratory muscles strength are scarce. Respiratory muscles performance and lung function were evaluated in children with SMA 1c and 2 after six injections of nusinersen (M14). Results from patients with SMA2 were compared with data of age-matched historical controls. Motor function tests (MFM and HINE-2) were assessed at baseline and M14 in the treated patients. RESULTS: Sixteen children (2 SMA Type 1c and 14 SMA Type 2), mean age 9.4 ± 2.3 years, were included. The data of 14 historical SMA 2 controls (mean age 9.3 ± 1.9 years) were gathered. The strength of the global inspiratory muscles of SMA 2 treated with nusinersen, assessed on maximal static inspiratory pressure, forced vital capacity, and esophageal pressure during a maximal sniff was significantly better compared with historical controls (p < .05). A significant improvement in MFM and HINE-2 was observed in the patients with 16 SMA treated with nusinersen after 14 months as compared with baseline. CONCLUSION: In children with SMA Type 2, respiratory muscle performance was significantly better after six injections of nusinersen as compared with age-matched SMA Type 2 historical controls.

Intravenous or nebulised magnesium sulphate versus standard therapy for severe acute asthma (3Mg trial): a double-blind, randomised controlled trial.

BACKGROUND: Previous studies suggested intravenous or nebulised magnesium sulphate (MgSO(4)) might improve respiratory function in patients with acute asthma. We aimed to determine whether intravenous or nebulised MgSO(4) improve symptoms of breathlessness and reduce the need for hospital admission in adults with severe acute asthma. METHODS: In our double-blind, placebo-controlled trial, we enrolled adults (aged ≥16 years) with severe acute asthma at emergency departments of 34 hospitals in the UK. We excluded patients with life-threatening features or contraindication to study drugs. We used a central randomisation system to allocate participants to intravenous MgSO(4) (2 g in 20 min) or nebulised MgSO(4) (three 500 mg doses in 1 h) alongside standard therapy including salbutamol, or placebo control plus standard therapy alone. We assessed two primary outcome measures in all eligible participants who started treatment, according to assigned treatment group: the proportion of patients admitted to hospital within 7 days and breathlessness measured on a 100 mm visual analogue scale (VAS) in the 2 h after initiation of treatment. We adjusted for multiple testing using Simes's method. The trial stopped before recruitment was completed because funding expired. This study is registered, number ISRCTN04417063. FINDINGS: Between July 30, 2008, and June 30, 2012, we recruited 1109 (92%) of 1200 patients proposed by the power calculation. 261 (79%) of 332 patients allocated nebulised MgSO(4) were admitted to hospital before 7 days, as were 285 (72%) of 394 patients allocated intravenous MgSO(4) and 281 (78%) of 358 controls. Breathlessness was assessed in 296 (89%) patients allocated nebulised MgSO(4), 357 (91%) patients allocated intravenous MgSO(4), and 323 (90%) controls. Rates of hospital admission did not differ between patients treated with either form of MgSO(4) compared with controls or between those treated with nebulised MgSO(4) and intravenous MgSO(4). Change in VAS breathlessness did not differ between active treatments and control, but change in VAS was greater for patients in the intravenous MgSO(4) group than it was in the nebulised MgSO(4) group (5·1 mm, 0·8 to 9·4; p=0·019). Intravenous or nebulised MgSO(4) did not significantly decrease rates of hospital admission and breathlessness compared with placebo: intravenous MgSO(4) was associated with an odds ratio of 0·73 (95% CI 0·51 to 1·04; p=0·083) for hospital admission and a change in VAS breathlessness of 2·6 mm (-1·6 to 6·8; p=0·231) compared with placebo; nebulised MgSO(4) was associated with an odds ratio of 0·96 (0·65 to 1·40; p=0·819) for hospital admission and a change in VAS breathlessness of -2·6 mm (-7·0 to 1·8; p=0·253) compared with placebo. INTERPRETATION: Our findings suggest nebulised MgSO(4) has no role in the management of severe acute asthma in adults and at best suggest only a limited role for intravenous MgSO(4) in this setting. FUNDING: UK National Institute for Health Research Health Technology Assessment Programme.

Magnesium sulphate in acute severe asthma in children (MAGNETIC): a randomised, placebo-controlled trial.

BACKGROUND: Little evidence is available for the effect of nebulised magnesium sulphate (MgSO(4)) in acute asthma in children. We assessed the effect of MgSO(4) treatment in children with severe acute asthma. METHODS: In this randomised placebo-controlled, multi-centre, parallel trial, we enrolled children (aged 2-16 years) with severe acute asthma who did not respond to standard inhaled treatment from 30 hospitals in the UK. Children were randomly allocated (1:1) to receive nebulised salbutamol and ipratropium bromide with either 2·5 mL of isotonic MgSO(4) (250 mmol/L; 151 mg per dose; MgSO(4) group) or 2·5 mL of isotonic saline (placebo group) on three occasions at 20-min intervals. Randomisation was done with a computer-generated randomisation sequence, with random block sizes of two to four. Both patients and researchers were masked to treatment allocation. The primary outcome measure was the Yung Asthma Severity Score (ASS) at 60 min post-randomisation. We used a statistical significance level of p<0·05 for a between-group difference, but regarded a between-group difference in ASS of 0·5 as the minimal clinically significant treatment effect. Analysis was done by intention to treat. This trial is registered with controlled-trials.com, number ISRCTN81456894. FINDINGS: Between Jan 3, 2009, and March 20, 2011, we recruited and randomly assigned 508 children to treatment: 252 to MgSO(4) and 256 to placebo. Mean ASS at 60 min was lower in the MgSO(4) group (4·72 [SD 1·37]) than it was in the placebo group (4·95 [SD 1·40]; adjusted difference -0·25, 95% CI -0·48 to -0·02; p=0·03). This difference, however, was not clinically significant. The clinical effect was larger in children with more severe asthma exacerbation (p=0·03) and those with symptoms present for less than 6 h (p=0·049). We detected no difference in the occurrence of adverse events between groups. INTERPRETATION: Overall, nebulised isotonic MgSO(4), given as an adjuvant to standard treatment, did not show a clinically significant improvement in mean ASS in children with acute severe asthma. However, the greatest clinical response was seen in children with more severe attacks (SaO(2)<92%) at presentation and those with preceding symptoms lasting less than 6 h. FUNDING: National Institute for Health Research Health Technology Assessment Programme.

Assessment of neuromuscular blockade produced by atracurium in the rat diaphragm preparation. Measurements of tetanic fade, depression and recovery profile.

The effect of atracurium, a relatively new muscle relaxant, on neuromuscular transmission, in the rat diaphragm preparation, was studied, by analysing the characteristic features of tetanic fade and recovery pattern following a blocking concentration of atracurium (10 microns). Tetanic fade (TF) and peak tetanic tension (Tp) and its depression by atracurium, were analysed and the results were interpreted in terms of atracurium action at the neuromuscular junction. Atracurium reduced the sustained tetanic tension, elicited at 50 Hz for 0.5 s duration, and produced a marked tetanic fade in 38 s. Atracurium also reduced the peak tetanic tension by 40%, of the control value, in 38 s. Maximum tetanic tension was 5.7 g tension, and the time taken to completely block the tetanus was 4.75 +/- 0.15 min (means +/- SE, n = 8). Recovery from atracurium-induced blockade occurred in 30s (tetanic fade) and in 3-4 min (peak tetanic tension). It was concluded that atracurium produces a profound tetanic fade, at a time when the peak tetanic tension is reduced by only 40%. The data presented indicate that atracurium has a rapid onset of blockade, intermediate duration and a quick recovery profile at the rat neuromuscular junction.