LUNG-FUNCTION MEASUREMENT IN AWAKE YOUNG-CHILDREN

The aim of the study was to evaluate methods applicable in a clinical setting for monitoring of changes in lung function in awake young chil dren. Impedance measurements by the impulse oscillation technique (ZIO S), respiratory resistance measurements by the interrupter technique ( Rint) and transcutaneous measurements of oxygen tension (Ptc,O-2) were compared with concomitant measurements of specific airway resistance (sRaw) and forced expiratory volume in one second (REV(1)) by whole bo dy plethysmography and spirometry, respectively, during methacholine c hallenge in 21 young children aged 4-6 yrs, with suspected asthma. Mea surements with each technique were repeated after each challenge step. A special face-mask was developed with an integrated mouthpiece which lung function ensured mouth breathing during the measurements. oscill ometry spirometry. The order of sensitivity of the techniques to asses s methacholine-induced changes in lung function was ZIOS > sRaw > Ptc, O-2 > FEV(1) > Rint. ZIOS was significantly more sensitive than all su bsequent methods, and Ptc,O-2 was significantly more sensitive than FE V(1). ZIOS, sRaw and Rint, but not Ptc,O-2 and FEV(1), detected the su bclinical increase in bronchial muscle tone in the children during bas eline, which was revealed by the significantly reduced airway obstruct ion after inhalation of a beta(2)-agonist as compared to baseline. It is concluded that ZIOS, Rint and Ptc,O-2 change in parallel with sRaw and FEV(1) and with a comparable sensitivity during simultaneous measu rements of the response to methacholine in young children aged 4-6 yrs . This implies that ZIos, Rint and Ptc,O-2 provide convenient indices of changes in lung function. Their combined use will be useful for mon itoring airway diseases of young children.