Reference values for peak flow and FEV₁ variation in healthy schoolchildren, using home spirometry

¹ Princess Amalia Children's Clinic, Isala klinieken, Zwolle, the Netherlands; and University of Groningen/University Medical Center, Beatrix Children's Hospital, Dept of paediatric Pulmonology, Groningen, the Netherlands
² Princess Amalia Children's Clinic, Isala klinieken, Zwolle, the Netherlands; and Presently at St Anna Zorggroep, Geldrop, the Netherlands
³ University of Groningen/University Medical Center, Beatrix Children's Hospital, Dept of paediatric Pulmonology, Groningen, the Netherlands
⁴ Princess Amalia Children's Clinic, Isala klinieken, Zwolle, the Netherlands

^* To whom correspondence should be addressed. E-mail: brouwerafj{at}bkk.umcg.nl.

	Abstract

Current reference values for diurnal peak flow variation in healthy children (median 8.2%; 95^th centile 31%) are so high that considerable overlap exists with asthmatic children. These values have been obtained with written peak flow diaries, which are unreliable.

To obtain reliable reference values of peak flow variation and forced expiratory volume in the 1^st second (FEV₁) variation in healthy schoolchildren using home spirometry with electronic data storage.

Two-hundred-and-four healthy schoolchildren (100 boys), 6–16 years of age, measured peak flow and FEV₁ twice daily for two weeks using an electronic home spirometer. Variation of peak flow and FEV₁ were calculated as diurnal amplitude as a percentage of the day's mean.

Mean peak flow variation was 6.2% (95%CI 5.8 to 6.7%; 95^th centile 12.3%) and mean FEV₁ variation was 5.7% (95%CI 5.4 to 6.1%; 95^th centile 11.8%).

Using home spirometry with electronic data storage, healthy schoolchildren show considerably less peak flow and FEV₁ variation than previously reported with written peak flow diaries. Being the 95^th centiles of the distributions in healthy children, we suggest using 12.3% for peak flow variation and 11.8% for FEV₁ variation as cut-off values for disease when using home spirometry.