Correlation between plethysmographic airway resistance and the interrupter technique in children

We evaluate correlations among airway resistance measured by the interrupter method with a new device (Microlab 4000, Micromedical) with those of standard pletismography. Twenty-two healthy children (mean age 10 +/- 3 yrs) without any remote or recent history of lung disease were enrolled in this study. All baseline values of lung function were within normal limits confirming health conditions. A highly significant degree of linear correlation was found between inspiratory (Rint-i) resistance of the interrupter method and all the pletismographic measurments (Raw-i r = 0.74, Raw-e r = 0.82, Raw-t r = 0,81, s-Gaw r = 0,73) and to a lesser extent with flows (FEV1 r = 0,61, FEF50 r = 0,73). A similar correlation was found with reciprocal of Rint, Gint-i except for FEV1; in contrast no statistical correlations were found between expiratory resistance (Rint-e) and pletismographic parameters except for Raw-i (r = 0,64); on the contrary Gint-e shows significant correlations with all parameters measured except for s-Gaw. These results,obtained in normal healthy well collaborating children, allow us to conclude that eventhough more and larger studies are necessary to better standardize the interrupter technique, this new device is able to bring new informations about the lung function in children.