Circadian rhythm of peak expiratory flow in asthmatic and normal children.

Henderson, A. J. W.; Carswell, F.

doi:10.1136/thx.44.5.410

Cited by 18 publications

(4 citation statements)

References 7 publications

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“…Most studies have reported greater diurnal variation in PEF both in adults and children with asthma using the (HI-LO)VRB index [12,19,[28][29][30]. However, HENDERSON and CARSWELL [31] found mean values of 8.8% in normal children and 12.5% in asthmatics -a smaller difference than in adults and similar to the low PEF variation in the present study. It may be that PEF variation is less marked in children and young people, and moreover a recent study by FRISCHER et al [30] found PEF variation to have low reproducibility in young children and a low sensitivity for diagnosing asthma.…”

Section: Discussioncontrasting

confidence: 55%

Home recording of PEF in young asthmatics: does it contribute to management?

Uwyyed¹,

Springer²,

Avital³

et al. 1996

Eur Respir J

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The value of home monitoring of peak expiratory flow (PEF) as part of an action plan for asthma management in children and young adults is uncertain. We sought to determine whether home recording of PEF benefited asthma management and whether any contribution was affected by the severity of the asthma.Twenty-eight children and young adults with asthma of different severity (mean age 14 yrs; 95% confidence interval (95% CI) 12-16 yrs) recorded their symptoms, drug consumption and PEF twice daily for a mean of 82 days over a 12 week period, and attended the laboratory every 2 weeks for measurement of lung function.The number of individual patients with significant correlations for laboratory lung function tests compared with ambulatory PEF and diary scores averaged over the preceeding 2 weeks was low in all severity groups. When measured in the laboratory, PEF meter readings correlated poorly with PEF measured by spirometry. The proportion of patients with significant correlations for PEF, symptoms and rescue bronchodilator use on a day-to-day basis was 70-80% in the group of severe asthmatics and significantly less in the mild asthmatics. In a subgroup of 14 patients who were sick on a mean of 19 days, the mean difference in PEF between well and sick days was 14% of predicted. Diurnal PEF variation correlated poorly with other parameters in all groups.It is concluded that PEF monitoring adds little to daily recording of symptoms and bronchodilator use in the management of young patients with severe asthma, and it is too insensitive to register meaningful clinical changes in those with milder asthma.

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Section: Discussioncontrasting

confidence: 55%

Home recording of PEF in young asthmatics: does it contribute to management?

Uwyyed¹,

Springer²,

Avital³

et al. 1996

Eur Respir J

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“…In asthmatic patients, the day-night differences in pulmonary functions were reversed when working the night instead of the day shift (Clark and Hetzel 1977). In healthy children, pulmonary resistance and compliance were found to be higher in the morning than in the afternoon hours in some, although not all, studies (Gaultier et al 1977(Gaultier et al , 1988Henderson and Carswell 1989). As in adults, peak expiratory flows in children were also higher in the afternoon hours (Casale et al 1992).…”

Section: Respiratory Mechanicsmentioning

confidence: 78%

Breathing around the clock: an overview of the circadian pattern of respiration

Mortola

2004

European Journal of Applied Physiology

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This article reviews human and animal studies about the circadian patterns of physiological variables involved with the respiratory function. Some measures reflecting the mechanical properties of the lungs, such as functional residual capacity, forced expiratory volumes and airway resistance, change periodically with the time of the day. Also resting pulmonary ventilation (V(E)), tidal volume, and breathing rate follow circadian patterns. In humans, these patterns occur independently of the daily changes in activity, whereas, to some extent, they are linked to changes in the state of arousal. Differently, in some rodents, the circadian oscillations of the breathing pattern occur independently of the daily rhythms of either activity or state of arousal. Recent measurements of the breathing pattern for unlimited periods of time in undisturbed animals have indicated that the circadian changes occur in close temporal phase with those of oxygen consumption, carbon dioxide production, and body temperature. However, none of these variables can fully explain the circadian pattern of breathing, the origin of which remains unclear. Both in humans and in rats the V(E) responses to hypercapnia or hypoxia differ at various times of the day. In rats, the daily differences in V(E) responses are buffered by changes in metabolic rate, such that, unlike humans, the hyperventilation (defined as the increase in ventilation-metabolism ratio) remains constant throughout the 24 h. The presence of a biological clock is a major advantage in the adaptation to the environment, although it forces some variables to deviate periodically from their mean value. In humans, these deviations become apparent in conditions of hypoxia. Hence, a daily time-window exists in which the respiratory system is less capable of responding to challenges, a factor which may contribute to the findings that some cardio-respiratory symptoms and diseases peak at particular times of the day.

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“…The mean daily PEF and the 08.00 16.00 and 20.00 h PEF means were calculated per 2 week period. Variability of daiiy PEF for each child was estimated by the formula: and the mean variability per 2 week period calculated [31]. Whenever peak flow was recorded, each child also recorded asthma symptoms (wheeze, cough, activity itnpairment and sleep disturbance) and medication use (type and frequency) in a standard diary card Air samples were collected from the bedrooms of the asthmatic children.…”

Section: Methodsmentioning

confidence: 99%