Gerald M. Loughlin

Determinants of growth in children with the obstructive sleep apnea syndrome.

Failure to thrive is a common complication of childhood obstructive sleep apnea syndrome (OSAS). To further evaluate its cause, we obtained 3-day dietary records, anthropometric measurements, polysomnography, and measurements of energy expenditure during sleep (SEE) in children with OSAS before and after tonsillectomy and adenoidectomy. Fourteen children were studied (mean age, 4 +/- 1 (SD) years). During initial polysomnography, patients had 6 +/- 3 episodes of obstructive apnea/hr, an arterial oxygen saturation nadir of 85% +/- 8%, and peak end-tidal carbon dioxide tension of 52 +/- 6 mm Hg. After surgery, OSAS resolved in all patients. The standard deviation score (z score) for weight increased from -0.30 +/- 1.47 to 0.04 +/- 1.34 (p < 0.005), despite unaltered caloric intake (91 +/- 30 vs 90 +/- 27 kcal/kg per day; not significant). The initial SEE (averaged over all sleep states) was 51 +/- 6 kcal/kg per day; postoperatively, it decreased to 46 +/- 7 kcal/kg per day (p < 0.005). Although SEE decreased during all sleep stages, the greatest decrease occurred during rapid eye movement sleep. The patients with the highest SEE on initial study had the lowest z scores (r = -0.62; p < 0.05). We conclude that SEE decreases and weight improves after resolution of OSAS. We speculate that the poor growth seen in some children with OSAS is secondary to increased caloric expenditure caused by increased work of breathing during sleep.

Sleep-disordered breathing in children with achondroplasia

OBJECTIVEnOur objective was to characterize sleep-disordered breathing in 88 children with achondroplasia aged 1 month to 12.6 years.nnnRESULTSnAt the time of their initial polysomnography, five children had previously undergone tracheostomy, and seven children required supplemental oxygen. Initial polysomnography demonstrated a median obstructive apnea index of 0 (range, 0 to 19.2 apneas/hr). The median number of central apneas with desaturation per study was 0.5 (0 to 49), the median oxygen saturation nadir was 91% (50% to 99%), and the median peak end-tidal pCO2 was 47 mm Hg (36 to 87 mm Hg). Forty-two children (47.7%) had abnormal initial study results, usually caused by hypoxemia. Two children with severe obstructive sleep apnea eventually required continuous positive airway pressure therapy, and three additional children required tracheostomies.nnnCONCLUSIONSn(1) Children with achondroplasia often have sleep-related respiratory disturbances, primarily hypoxemia. (2) The majority do not have significant obstructive or central apnea; however, a substantial minority are severely affected. (3) Tonsillectomy and adenoidectomy decreases the degree of upper airway obstruction in most but not all children with achondroplasia and obstructive sleep apnea. (4) Restrictive lung disease can present at a young age in children with achondroplasia.

Polysomnographic characteristics of patients with Rett syndrome

During wakefulness, patients with Rett syndrome have disordered breathing. To understand further this ventilatory control disorder, we performed polysomnography in 30 patients with Rett syndrome and 30 control subjects (female subjects with primary snoring). The median age was 7 years (range, 1 to 32 years) for Rett syndrome and 6 years (range, 1 to 17 years) for control subjects. During periods of wakefulness, 67% of patients with Rett syndrome had the characteristic pattern of disordered breathing (i.e., episodes of hyperventilation followed by central apnea and desaturation). No such events occurred during sleep. Sleep efficiency and sleep architecture were similar for both groups. During sleep, there was no difference in duration of periodic breathing, number of episodes of central apnea with desaturation, or number of episodes of obstructive apnea or end-tidal carbon dioxide tension between the two groups. Although arterial oxygen saturation during rapid eye movement (REM) sleep was slightly lower in patients with Rett syndrome (nadir, 94% +/- 2% vs 96% +/- 2%), it remained within the normal range. Parental history reflected the awake respiratory findings in most cases. We conclude that patients with Rett syndrome have normal breathing during non-rapid eye movement (NREM) sleep. We speculate that patients with Rett syndrome have normal brain-stem control of ventilation, and that the disordered breathing seen during wakefulness is due to an abnormality of the cortical influence on ventilation.

Pulmonary function in juvenile rheumatoid arthritis

12. Galanello R, Melis MA, Ruggeri R, Addis M, Scalas MT, Maccioni L, Furbetta M, Angius A, Tuveri T, and Cao A: fl~ trait in Sardinian, Hemoglobin 333, 1979. 13. Beaven GH, Ellis M J, and White JC: Studies on human 14. fetal haemoglobin. III. The hereditary haemoglobinopathies and thalassaemias, Br J Haematol 7:169, 1961. Luzzatto L: Genetics of red cells and susceptibility to malaria, Blood 54:961, 1979.

Clinical application of transepithelial potential difference measurements in cystic fibrosis

We studied transepithelial potential difference (PD) in normal persons, patients with chronic disease, and patients with cystic fibrosis (CF), using the technique described by Knowles and co-workers. A maximal PD value (PDmax) and an average PD value (PDmean) were determined for each study of the nasal respiratory epithelium. The voltage response to superfusion of 10(-4) mol/L amiloride onto nasal mucosa was noted. The PD of the palm, wrist, and between two fingertips was also measured. Nasal PDmax and PDmean of the CF group were more negative than the control (P less than 0.01) and chronic disease groups (P less than 0.01). After application of amiloride, the voltage change in nasal PD was greater in the CF group than in the non-CF control groups (P less than 0.01). There were no clinically significant differences in the PD of the palm, wrist, or fingertips of the three groups. These data confirm the observation that patients with CF have hyperpolarized nasal epithelia that demonstrate greater change in response to amiloride than that in non-CF controls. These results indicate a possible role for the use of in vivo nasal PD measurements as a diagnostic test for cystic fibrosis.

Immune-complex-mediated glomerulonephritis and pulmonary hemorrhage simulating Goodpasture syndrome

Two female children whose clinical presentations and renal light-microscopic findings were consistent with Goodpasture syndrome are described. Immunopathologic studies demonstrated granular deposition of immunoglobulins and complement, suggesting that the renal disease was mediated by circulating immune complexes and not by anti-glomerular basement membrane antibody. Anti-GBM antibody was absent in both patients. These patients represent the first report in children of idiopathic nephritis due to immune complexes with associated pulmonary hemorrhage. The findings raise some doubt as to the accuracy of previous reports of Goodpasture syndrome in children, and also demonstrate the diagnostic and therapeutic importance of evaluation the renal immunopathology in the child with nephritis and pulmonary hemorrhage.

Pulmonary function in children with a history of laryngotracheobronchitis1

Baseline, postexercise, and postisoproterenol lung function was studied in 27 children, 8 to 18 years of age, with a past history of laryngotracheobronchitis (croup) and in ten children without such a history. The LTB subjects were divided into two groups, based on the presence or absence of allergies. Baseline flow tests were similar in all groups but small airway function was mildly abnormal in several members of each group. There was no consistent response to isoproterenol inhalation among those who had had croup and normal subjects. Following exercise, however, a significant (P less than 0.05) number of subjects (14 of 27) in both LTB groups demonstrated bronchoconstriction with a greater than 10% drop in peak expiratory flows. From these studies, it appears that children with a past history of croup have a higher prevalence of increased bronchial reactivity, which occurs irrespective of allergy and baseline lung function abnormalities.

Original articlePulmonary function in children with a history of laryngotracheobronchitis1

Baseline, postexercise, and postisoproterenol lung function was studied in 27 children, 8 to 18 years of age, with a past history of laryngotracheobronchitis (croup) and in ten children without such a history. The LTB subjects were divided into two groups, based on the presence or absence of allergies. Baseline flow tests were similar in all groups but small airway function was mildly abnormal in several members of each group. There was no consistent response to isoproterenol inhalation among those who had had croup and normal subjects. Following exercise, however, a significant (P less than 0.05) number of subjects (14 of 27) in both LTB groups demonstrated bronchoconstriction with a greater than 10% drop in peak expiratory flows. From these studies, it appears that children with a past history of croup have a higher prevalence of increased bronchial reactivity, which occurs irrespective of allergy and baseline lung function abnormalities.