2002 Volume 16 Issue 5 Pages 493-500
We have often experienced that values of respiratory function test (flow-volume curves) differ depending on the posture of the subjects. To investigate which of the postures, standing or sitting, is more appropriate to measure flow-volume curve in order to prospect asthma attacks in children, we measured flow-volume curves during forced expiration in 122 asthma patients who were followed up at our out-patient clinic. The measurements were done three times each in standing position at the out-patient clinic, and sitting position at the respiratory function laboratory for each patient. The equipment used at the laboratory was only for sitting position, while the equipment used at the out-patient clinic was basically for standing position. Then, we estimated %FVC, and FEV1.0%, %v50, and %v25 in each position, and compared the respective parameters in different positions. %FVC and FEV1.0% estimated in standing position were not significantly different from those in sitting position, while %v50 and %v25 in standing position were significantly higher than those in sitting position, respectively. %v50 and %v25 in both standing and sitting position of the patients who had asthma attacks two weeks before and/or after the measurement were significantly lower than those who did not have attacks in those period. However, those parameters estimated in sitting position varied widely from patient to patient. Moreover, they were significantly lower in younger patients than in older patients even in the group without attacks. Thus, we concluded that flow-volume curves measured in standing position were more appropriate as an indicator of the control of pediatric asthma patients than those measured in sitting position, especially in younger patients.
