Flow dependence of specific airway resistance and diagnostic of asthma in children

Abstract

Panting majors turbulent flow and contribution of larger airways to the measurement of specific airway resistance (sRaw). The hypothesis was tested that the difference between asthmatic and healthy children is enhanced by narrowing the flow interval to compute sRaw. sRaw was measured during panting in 40 asthmatic and 25 healthy children and computed using all data points (full scale flow) and limited to the flow intervals ± 1L/sec and ± 0.5 L/sec. sRaw was not different between asthmatics (0.87 ± 0.20 kPa.s) and controls (0.80 ± 0.25 kPa.s) when computed full scale, while it was significantly larger in asthmatics than controls within ± 1L/sec (0.77 ± 0.16 kPa.s vs 0.65 ± 0.15 kPa.s, P < 0.004) or ± 0.5 L/sec (0.77 ± 0.21 kPa.s vs 0.61 ± 0.17 kPa.s, P < 0.002). On the other hand, the within subject coefficient of variation was significantly larger when sRaw was computed within ± 1L/sec (13.7 ± 7.2%) or ± 0.5 L/sec (28.3 ± 18.1%) than full scale (11.0 ± 6.7%), respectively P < 0.002 and P < 0.0001. It is concluded that narrowing the flow interval to compute sRaw is associated with better discrimination between asthma and health in children, although the short term variability of sRaw is increased.

A Calibration Device to Compare Body Plethysmographs Among Pediatric Lung Function Laboratories

“…Nevertheless these figures are within those reported for sRaw in non-naïve adult subjects, i.e., 10% variability and 20% between day repeatability ( Peslin et al, 1987 ). Also, the estimated short term coefficient of variation for either sRa here is well within those reported for clinical measurements of sRaw – about 10% – in healthy or asthmatic children ( Bisgaard and Klug, 1995 ; Klug and Bisgaard, 1997 ; Coutier et al, 2015 ; Ioan et al, 2016 ). The between session repeatability was within 5% for all analog parameters, an important result in the context of between laboratory equipment comparison, while the between day variability in healthy adult subjects was reported to be respectively, about 6% for thoracic gas volume and 20% for sRaw ( Peslin et al, 1987 ).…”

Specific airway resistance in preschool children: why not panting after all?

“…Furthermore, the larger variability observed with sRtot compared with sRaw 0.5 was also expected, especially during panting, as the ventilatory effort is likely to vary from one breath to another, resulting in variable flow amplitude and contribution of nonlinearities throughout the acquisition. Hence, computation over a limited flow interval as reported in adults should be recommended [12], with the recent indication of better separation of children with asthma from controls based on sRaw 0.5 [13]. However, it should be kept in mind that, in preschool children where ΔVpleth and flow signals are small, computation of sRaw within a limited flow range may compromise the signal-to-noise ratio.…”

Relationship between baseline and post-bronchodilator interrupter resistance and specific airway resistance in preschool children

“…In our study, measurement during tidal breathing was chosen for its feasibility with ease among our younger population (3-6 yo) compared to that of Coutier et al (6.5-11.5 yo). 26 The agreement between Rint and sRaw was fair (Cohen Kappa coefficient = 0.33) in positive BDR but higher than that in baseline z-scores. This was consistent with other works reporting that BDR is better than resistance baseline zscores to highlight bronchial hyper reactivity and hence leading to better prevention, diagnosis and management of asthma in children.…”