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Asthma is increasingly recognized as heterogeneous, characterized by different endotypes, with obesity not only a distinct phenotype but a risk factor for severe asthma.

Asthma is among the most frequent chronic diseases in childhood. Although numerous environmental risk factors have already been identified, the basis for familial occurrence of asthma remains unclear. Previous genome screens for atopy in British/Australian families and for asthma in different American populations showed inconsistent results. We report a sib pair study of a sample of 97 families, including 415 persons and 156 sib pairs. Following an extensive clinical evaluation, all participants were genotyped for 351 polymorphic dinucleotide markers. Linkage analysis for asthma identified four chromosomal regions that could to be linked to asthma: chromosome 2 (at marker D2S2298,P= 0.007), chromosome 6 (around D6S291, lowestP= 0.008), chromosome 9 (proximal to D9S1784,P= 0.007), and chromosome 12 (D12S351,P= 0.010). These linkage regions could be reproduced for all loci by analysis of total or specific immunoglobulin E (minimumPvalues at these regions were 0.003, 0.001, 0.010, and 0.015, respectively).

Changes in respiratory mechanics and timing produced by continuous negative extrathoracic pressure (CNEP) of −0.6 kPa were assessed in 18 infants recovering from neonatal respiratory distress syndrome. The median gestational age was 28 wk (range 24–36 wk). All infants were recruited before discharge from neonatal intensive care and were measured at a median postnatal age of 58 d (range 10–127 d) and a median weight of 2.67 kg (range 1.99–3.77 kg). All had been treated for respiratory distress syndrome; 11 were diagnosed as having chronic lung disease. At the time of the study, all infants were stable breathing room air. There was a significant decrease of the respiratory rate in all but one infant from 63.6 ± 10.0 to 49.3 ± 9.1 breaths per min (mean ± SD) during CNEP. This was predominantly due to a marked prolongation of the expiratory time. Passive respiratory mechanics were assessed using airway occlusion techniques. Whereas respiratory system compliance (Crs) did not change in the infants with a normal baseline measurement, there was a significant improvement of Crsin the 11 infants with low Crsvalues in atmosphere: In the latter, all of whom were very-low-birth-weight infants, Crsassessed by the multiple occlusion technique (mean ± SD) corrected for body weight in-creased from 7.9 ± 1.5 to 9.4 ± 1.9 mL.kPa−1. kg−1in CNEP (p= 0.012). There was no consistent change in respiratory system resistance in this population of 18 infants. These preliminary results suggest that the beneficial effects of CNEP observed in clinical studies may be partially explained by its effects on respiratory mechanics and timing.

ABSTRACT: Changes in respiratory mechanics and timing produced by continuous negative extrathoracic pressure (CNEP) of −0.6 kPa were assessed in 18 infants recovering from neonatal respiratory distress syndrome. The median gestational age was 28 wk (range 24–36 wk). All infants were recruited before discharge from neonatal intensive care and were measured at a median postnatal age of 58 d (range 10–127 d) and a median weight of 2.67 kg (range 1.99–3.77 kg). All had been treated for respiratory distress syndrome; 11 were diagnosed as having chronic lung disease. At the time of the study, all infants were stable breathing room air. There was a significant decrease of the respiratory rate in all but one infant from 63.6 ± 10.0 to 49.3 ± 9.1 breaths per min (mean ± SD) during CNEP. This was predominantly due to a marked prolongation of the expiratory time. Passive respiratory mechanics were assessed using airway occlusion techniques. Whereas respiratory system compliance (Crs) did not change in the infants with a normal baseline measurement, there was a significant improvement of Crsin the 11 infants with low Crsvalues in atmosphere: In the latter, all of whom were very-low-birth-weight infants, Crsassessed by the multiple occlusion technique (mean ± SD) corrected for body weight in-creased from 7.9 ± 1.5 to 9.4 ± 1.9 mL·kPa−1. kg−1in CNEP (p = 0.012). There was no consistent change in respiratory system resistance in this population of 18 infants. These preliminary results suggest that the beneficial effects of CNEP observed in clinical studies may be partially explained by its effects on respiratory mechanics and timing.

The nitrogen washout technique usually involves exposure of the patient to 100% oxygen for several minutes. This may be dangerous in preterm infants who are at risk of retinopathy of prematurity (ROP). We wanted to know whether heliox (79% He, 21% O2) can be used instead of oxygen when determining functional residual capacity (FRC). FRC measurements were made in 14 preterm infants [median (range) gestational age at birth 34 wk (27-37 wk), and at time of study 36 wk (33-40 wk)] who were breathing room air. FRC was measured using a computerized infant pulmonary function system, beginning in random order with either 100% O2followed by heliox or vice versa. There was no systematic difference between the two methods with regard to lung volume measurements: mean (SD) FRC values, corrected for body weight, were 22.9 (7.1) mL/kg for O2and 23.4 (7.0) mL/kg for heliox. We did not observe a systematic influence of the type of washing gas used (heliox or oxygen) on FRC in these infants. Our results suggest that the use of heliox instead of pure oxygen may be a suitable and safer alternative for FRC measurements with the nitrogen washout technique in preterm infants who are breathing low concentrations of inspired oxygen and are still at risk of ROP.

Abnormal weights, e.g. Obesity, has shown strong modifying effect on the association between air pollution exposure and lung function impairment in adults.