SUMMARY Lung function was recorded in a cohort of 130 age specific children of low birth weight (under 2000 g) and a reference population of 120 unselected local schoolchildren at 7 years of age. Children of the cohort were similar in height and forced vital capacity to the reference group, but had significantly reduced forced expiratory volume in 0-75 second and expiratory flow indices. Although neonatal respiratory illness was associated with reduced airway function, we were unable to confirm that this was a consequence of oxygen treatment or mechanical ventilation. Low birth weight, however, was closely associated with poor airway function independent of neonatal respiratory illness. Other factors of importance included the male gender and maternal smoking. The reduction in airway function observed in the low birthweight children was associated with cough but not wheeze. The disparity between the relatively well preserved vital capacity and reduced airway function suggests that very low birth weight, and hence prematurity, has its greatest effect on the subsequent growth of airway function.

SUMMARY Twenty two boys with Duchenne muscular dystrophy were entered into a randomised double blind crossover trial to compare respiratory muscle training with a Triflow II inspirometer and 'placebo' training with a mini peak flow meter. Supine posture was associated with significantly impaired lung function, but respiratory muscle training showed no benefit.The fundamental respiratory problem in Duchenne muscular dystrophy is progressive intercostal and diaphragmatic muscle weakness often complicated by scoliosis. In practice the absolute lung volumes and forced expiratory flow measurements increase up to the age of 10-12 years, after which they fail to improve further with age, producing a fall in spirometric indices in late teenage life with deterioration in blood gas concentrations and eventual death.One potential method of improving lung function in Duchenne muscular dystrophy is respiratory muscle training. Such a method would be useful as a means of preparing the child for surgery. Martin et a12 and Houser et a13 have claimed benefit from respiratory muscle training, but neither used a control period of placebo training. We performed a double blind, placebo controlled, crossover study to evaluate the effect of short term respiratory muscle training on lung function. Patients and methodsTwenty two boys with Duchenne muscular dystrophy aged 9-14 years (mean 11.6) were recruited from two special schools where they received daily physiotherapy. They were randomised to receive either respiratory muscle training using a Triflow IL Inspirometer (Cheseborough Ponds) to a total of 20 inspirations/day, or 'placebo' training using a mini peak flow meter to a total of 10 expirations/day, administered by the school physiotherapists. To compare the effect of Triflow and placebo training we applied a standard crossover analysis that permits the treatment to be compared by paired t test among all subjects if the order of administration does not alter the treatment effect.6 ResultsOf the 22 children recruited to the study two were withdrawn because of illness during the study period. Eleven children started with 'placebo' respiratory muscle training using the mini peak flow meter, and crossed over to the Triflow inspirometer during the second three week period (group 1). Nine children performed the training in the reverse order (group 2). There was a significant fall in FVC when spirometry was performed in the supine position on 10 May 2018 by guest. Protected by copyright.

SUMMARY In a prospective study on a cohort of 7 year old children of low birth weight (under 2000 g at birth), we observed an increased prevalence of airway responsiveness to histamine compared with a reference population of unselected, local schoolchildren. The airway responsiveness to histamine was significantly related to a history of asthma in first degree relatives (natural parents and siblings) in both groups of children, but not to that of the mothers. There was no increase in the prevalence of maternal asthma, a family history of asthma, or airway responsiveness in the mothers of low birthweight children. We were unable to find evidence to support the hypothesis that maternal smooth muscle irritability (uterine and airway) has a causative role in the premature labour in the mothers and in subsequent bronchial hyperresponsiveness in their prematurely born children.

SUMMARY Effects of posture and spinal bracing on lung function were studied in 40 children with neuromusclar disease, 20 of whom had scoliosis and were non-ambulant. Change from sitting to supine position had little effect on lung function in ambulant children, but caused a significant 12% reduction in forced vital capacity in a group of 16 non-ambulant children with scoliosis, suggesting diaphragmatic weakness in some. Spinal bracing, using a rigid supporting jacket, resulted in a significant reduction in mean vital capacity of 22%. The degree of impairment in forced vital capacity was proportional to the severity of the scoliosis (as measured by the Cobb's angle), to the amount of correction achieved by the brace, and to the degree of diaphragmatic weakness. Spinal bracing in a child with established severe scoliosis causes appreciable respiratory impairment, and this may explain why it is less likely to be tolerated than early prophylactic bracing.

Eighteen infants were entered into a randomized, placebo-controlled trial of dexamethasone therapy for chronic lung disease. Initial ventilation requirements were similar in the two groups, although all infants were in headbox oxygen on entry to the trial. The dexamethasone-treated infants showed a significantly more rapid improvement during the 1st week of treatment, although the overall duration of oxygen therapy was similar in both groups. Cranial ultrasound examination revealed new periventricular abnormalities in three out of the five dexamethasone-treated infants who had previously normal scans, compared with none of four similar placebo-treated infants. A large trial, focussing on potential complications, is now needed.