Reversibility of lung function in pre-school children with asthma or asthma-like symptoms

Abstract

Background.

Diagnosing asthma in pre-school children with asthma-like symptoms is a major problem. From a clinical viewpoint, because of the specificity and variability of symptoms, it is currently almost impossible to distinguish the asthmatic from the non-asthmatic child. Since asthma is defined as a reversible airway obstruction reversibility testing could be of additional value.

Aim.

To assess reversibility of lung function in pre-school children with asthma or asthma-like symptoms. Methods. In symptomatic children, included in the ASTERISK (Astma, Symptomen, Therapie En RISiKo factoren) study, airway resistance (pre/post salbutamol) was measured by means of interrupter technique (Rint) and forced oscillation technique (FOT) when possible.

Results.

96 Children were included in the ASTERISK study (69% male; mean age 2.6 (1.2) yr.). Lung function measurements were successful in 53 (55%) and 35 (36%) children (respectively Rint and FOT). The succes rate increases with age (table 1). Lung function significantly improved after salbutamol (table 2).

Table 1. Success rates (%): 5 acceptable measurements.

Age Rint FOT

1-2 yr (n= 38) 16 % 0 %

2-3 yr (n= 21) 71 % 38 %

3-4 yr (n= 19) 74 % 53 %

4-5 yr (n= 18) 100 % 94 %

Table 2. Lung function pre/post salbutamol (mean (S.D.));

Lung function Pre Post

Rint (n=53) Resistance (kPa.s/L) 1.2 (0.6) 0.9 (0.4)^*

FOT (n=35) Resistance (hPa.s/L) 7.8 (1.7) 6.7 (1.6)^*

Resistance at 6Hz (hPa.s/L) 9.7 (2.7) 7.7 (2.0)^*

^* p<0.05 after Wilcoxon U test.

Conclusion.

Reversibility testing in pre-school children with asthma or asthma-like symptoms is possible using Rint and FOT. However, the diagnostic value of this measurement needs to be determined further.