Spirometer Calibration Check Procedures

drastically displaced. From our side, this has lead to an intelligent analytical procedure that we call “InCAP,” which groups waveforms into clusters.3 The cluster that most closely agrees with the normal capnogram is used for calculating PETCO2. This analysis system provides considerably better agreement between the data from cluster 1 and the PaCO2 value. The problematic nature of the conventional analysis of capnometers for the PETCO2 value is underscored by the form and number of capnograms recorded during spontaneous respiration. Table 1 shows the improved agreement, represented by the curves after grouping into 5 clusters (taken from 3). Furthermore, it is clear that the gas sampling is more effective with Oridion’s oral/nasal cannula system than with a face mask. This effect could not be deduced from the data we presented.4 We stress that the analysis of gas samples is much more complex for patients breathing spontaneously than for patients undergoing artificial ventilation. Here one should not so much push the technique to the forefront, but should rather point out that alternative assessment procedures should be offered. We thank Dr Lain for bringing this subject to the discussion table. Hartmut Gehring MD on behalf of the all authors Department of Anesthesiology University Clinic of Schleswig-Holstein Luebeck, Germany