Effects of overweight on lung function.

Spirometric data from 1586 healthy children, who did not smoke, were analysed to examine the effects of overweight as measured by the body mass index (weight/height2) on lung function. Overweight (72 boys, 88 girls) was defined as on or above the 90th percentile weight for height. After having controlled for the confounding variables of height and age, there were positive partial correlations between body mass index and lung function in girls whose weight was normal, in overweight girls, and in boys whose weight was normal, but not in overweight boys. In contrast to adults, body mass index has a positive effect on lung function in girls, whatever their weight. No such correlation between body mass index and lung function was seen in overweight boys. The observations may be accounted for by distinct sex dependent patterns of fat distribution in children.

Properties and clinical implications of body mass indices.

The properties of body mass indices were evaluated in a cross sectional study of the weights and heights of 5016 Chinese boys and girls aged between 3 and 18 years. Of the indices examined (weight/height (W/H), weight/height2 (W/H2), weight/height3 (W/H3) and weight/heightp (W/Hp], W/Hp was the only one that consistently showed least correlation with height, and so could be regarded as the optimal body mass index by the criterion of independence of the index from height. The exponent 'p' of W/Hp is, however, highly dependent on age; the value increases steadily between the age of 3 and 7-9 years, and then varies considerably around puberty. Only the age specific exponent ensures a lack of correlation between body mass index (W/Hp) and height. Age specific W/Hp should therefore be used in intrapopulation studies of weight or problems associated with obesity in children. Interpopulation comparison of weight and adiposity by W/H, W/H2, or W/H3 may give misleading results because of their dependence on height. Our results also suggest that the conventional weight for height charts may not be accurate enough for clinical use.

Slow-release terbutaline and theophylline for the long-term therapy of children with asthma: a Latin square and factorial study of drug effects and interactions.

To evaluate the long-term effects of slow-release formulations of theophylline and terbutaline on pulmonary function, clinical symptoms, and side effects, 24 children with stable and moderately severe perennial asthma participated in a prospective double-blind cross-over study. The patients and the treatments were randomized according to the Latin square design to eliminate all possible period/climate biases throughout the protracted study period. The treatments consisted of terbutaline, 5 mg, theophylline, 200 mg, the combination, and placebo, given twice daily orally and crossing over every 28 days. The two drugs, administered alone or in combination, improved lung function and symptoms when compared with placebo. The interaction of theophylline and terbutaline was quantitatively shown by 2 x 2 factorial statistical design to be essentially additive rather than synergistic in the control of asthma. No increase in side effects was noted when the combined therapy was used. These findings suggest therapeutic advantages to combining submaximal oral doses of sustained-release theophylline and terbutaline for the long-term treatment of children with asthma.

Hyperinsulinism in infancy.

Five infants with persistent hypoglycaemia due to hyperinsulinism were reported. Provocative tests for insulin release were unhelpful. Diazoxide was useful in the treatment of three patients but many side-effects were observed. These included petechial rash, hypertrichosis, acute renal failure, fluid retention and cardiac failure. Two patients underwent spontaneous remission. Three patients had nesidioblastosis, two of whom were subjected to 95% pancreatectomy. Postoperatively, recurrence of hypoglycaemia was due to hyperinsulinism in one patient and to presumed glucagon deficiency in the other. Phenytoin effectively corrected the hypoglycaemia in the patient who had postoperative hyperinsulinism. It is recommended that medical therapy with diazoxide (10-15 mg/kg per day) together with a diuretic be commenced once hyperinsulinism is diagnosed. Subtotal pancreatectomy should be performed early in these patients if hypoglycaemia cannot be controlled with medical therapy or if side-effects of treatment are documented.

Pulmonary function in thalassemia major.

Pulmonary function tests were evaluated in 28 Chinese patients with beta-thalassemia major receiving regular transfusions and desferoxamine, and in 34 height-matched normal Chinese children. Comparison of lung function using analysis of covariance with reference to standing height showed that patients with thalassemia had a proportional decrease in forced vital capacity and forced expiratory flow volume in 1 second, whereas their expiratory flow rates, residual volume, and total lung capacity were comparable to those in normal children. The single-breath carbon monoxide diffusion capacity was normal. Our findings suggest that children with thalassemia major have mild restrictive lung disease. The previous controversy regarding the presence of restrictive or obstructive lung disease in patients with thalassemia may be related to the use of inappropriate control values.

Attenuation of exercise-induced asthma by acupuncture.

A prospective randomised single-blind study of the effects of real and sham acupuncture on exercise-induced asthma was conducted in nineteen children. Forced expiratory flow in 1st second (FEV1), forced vital capacity (FVC), and peak expiratory flow rate (PEFR) were measured throughout acupuncture and after treadmill exercise. Neither real nor sham acupuncture affected the basal bronchomotor tone but both, when applied 20 min before exercise, attenuated exercise induced asthma: mean maximum percentage falls in FEV1, FVC, and PEFR were 44.4%, 33.3%, and 49.5% without acupuncture; 23.8%, 15.8%, and 25.9% after real acupuncture; and 32.6%, 26.1%, and 34.3% after sham acupuncture. Real acupuncture provided better protection against exercise-induced asthma than did sham acupuncture (p less than 0.05).