The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Comparative Study
Short-term variations in oscillatory and spirometric lung function indices among school children.
The aim of this study was to compare immediate, daily and weekly variation in respiratory resistance measured by means of the forced oscillation technique (Rrs,FOT) to spirometric indices in 7-12 year old children with chronic respiratory symptoms. The lung function measurements were performed in 19 children on 4 days, i.e. two consecutive days during two consecutive weeks. On each day, the measurements were carried out at the same time of day and always repeated three times. ⋯ When a reliability index was applied, the immediate variation in Rrs,FOT values was comparable to those of the airflow indices at specified lung volumes. Rrs,FOT was also the most sensitive index in the exercise challenge test, and therefore it seems to be suitable for detection of short-term functional changes in the respiratory system. However, the relatively low repeatability of Rrs,FOT over days and weeks may limit its applicability to longer-term follow-ups.
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Comparative Study
Size and strength of the respiratory and quadriceps muscles in patients with chronic asthma.
There have been few studies of respiratory and limb muscle size and function in middle-aged patients with asthma and persistent airways obstruction. We have compared the forces generated by the respiratory and thigh muscles with their dimensions assessed by ultrasound in nine middle-aged patients with chronic asthma (mean age 56 (SD 8) yrs; functional residual capacity/total lung capacity ratio (FRC/TLC) 60 (10)%), and in nine normal subjects (aged 53 (7) yrs; FRC/TLC 55 (5)%). Diaphragm thickness was measured at the zone of apposition by B-mode ultrasound during relaxation (DiTrelax) and during a maximum-effort inspiratory manoeuvre (DiTpI,max) at FRC. ⋯ Middle-aged patients with chronic asthma and a small increase in functional residual capacity/total lung capacity ratio have preserved limb muscle force and dimensions, modestly impaired inspiratory muscle strength, and slightly increased thickness of the costal diaphragm. Future studies of respiratory muscle function in asthma should be aided by measurement of diaphragm thickness and of limb muscle strength and size. Such studies are required particularly in older patients with severe hyperinflation who are most likely to have impairment of muscle function.