[Respiratory resistance measured by interrupter technique in asthmatic children. Correlation with spirometry]

Abstract

Respiratory resistance measured by the interrupter technique (Rocc) is very attractive in young children because minimal comprehension and coordination are needed. It is feasible in children below 5 years of age, in children with acute asthma and the device is simple, small sized, and relatively cheap. The objective of this study was to determine the correlation between Rocc and spirometry in co-operative children with asthma. We studied patients with asthma old enough to perform spirometry. The spirometric parameters evaluated were forced vital capacity (FVC), forced expiratory flow in 1 second (FEV1), peak expiratory flow (PEF), and maximal expiratory flow at 50% of vital capacity (MEF50). Respiratory resistance was measured during normal breathing, with a nose clip, with the neck in slight extension. The maneuver was repeated until 5 relatively constants values were obtained. The mean value was evaluated. We analyzed the results by the Pearson correlation quotient. Thirty-four children were tested (20 boys) with a mead age of 8,91 years (limits: 4-18 years), a mean height of 135.88 cm (106-173 cm), a mean weight of 33.95 kg (17-66 kg). Rocc correlated well with FVC (r = -0.81; p < 0.05), with FEV1 (r = -0.79; p < 0.05), with PEF (r = -0.76; p < 0.05), and with MEF50 (r = -0.76; p < 0.05). In conclusion, Rocc values correlated well with the main spirometric parameters, and this method (Rocc) could be used as a substitute of spirometry in young children, who cannot perform forced expiratory maneuvers.