[A new device for measuring occlusion pressure]

Mouth pressure in the first 100 ms of inspiration with the airway occluded (P0.1) is an indirect measure of central airways activity. Few adequately validated devices are available on the market for measuring this variable automatically, impeding wider use of this measurement. Our aim was to determine the validity and precision of a new automatized manometer for measuring P0.1 and compare the device to the apparatus normally used in our laboratory. The newly manufactured device consisted of a semiconductor type pressure transduce connected to an analog-to-digital converter. The usual apparatus used was constructed in our laboratory from a Honewell transducer, an analog-to-digital card (Data Translation DT2801) for an IBM-compatible PC and a standard spread sheet program. Both devices recorded a continuous signal at a sample frequency of 100 Hz. To determine linearity, accuracy, sensitivity and precision, two columns of 5 and 25 cmH2O were used. For clinical assessment, 33 patients scheduled for lung function analysis were tested. Five measurements of P0.1 were performed on each. The sensitivity of the new device was 0.1 cmH2O; precision expressed as a variation coefficient was 0%, and linearity expressed as a correlation coefficient was r = 0.999 between the two columns. The mean difference between the two devices was 0.11 (0.46) cmH2O (p < 0.0001). Analysis of concordance confirmed a reading bias for the new device in comparison with the usual one, although the difference was not clinically significant (0.08 to 0.14 cmH2O). We conclude that the new device gives good results and its availability on the market may allow more frequent clinical application of occlusion pressure measurement.