科研之友
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摘要
BACKGROUND: Recent findings suggest that using alveolar P-CO2 (P-ACO2) estimated by volumetric capnography in the Bohr equation instead of P-aCO2 (Enghoff modification) could be appropriate for the calculation of physiological dead space to tidal volume ratio (V-D/V-T Bohr and V-D/V-T Enghoff, respectively). We aimed to describe the relationship between these 2 measurements in mechanically ventilated children and their significance in cases of ARDS. METHODS: From June 2013 to December 2013, mechanically ventilated children with various respiratory conditions were included in this study. Demographic data, medical history, and ventilatory parameters were recorded. Volumetric capnography indices (NM3 monitor) were obtained over a period of 5 min preceding a blood sample. Bohr's and Enghoff's dead space, S2 and S3 slopes, and the S2/S3 ratio were calculated breath-by-breath using dedicated software (FlowTool). This study was approved by Ste-Justine research ethics review board. RESULTS: Thirty-four subjects were analyzed. Mean V-D/V-T Bohr was 0.39 +/- 0.12, and V-D/V-T Enghoff was 0.47 +/- 0.13 (P = .02). The difference between V-D/V-T Bohr and V-D/V-T Enghoff was correlated with P-aO2/F-IO2 and with S2/S3. In subjects without lung disease (P-aO2/FIO2 >= 300), mean V-D/V-T Bohr was 0.36 +/- 0.11, and V-D/V-T Enghoff was 0.39 +/- 0.11 (P = .056). Two children with status asthmaticus had a major difference between V-D/V-T Bohr and V-D/V-T Enghoff in the absence of a low P-aO2/F-IO2. CONCLUSIONS: This study suggests that V-D/V-T Bohr and V-D/V-T Enghoff are not different when there is no hypoxemia (P-aO2/F-IO2 > 300) except in the case of status asthmaticus. In subjects with a low P-aO2/F-IO2, the method to measure V-D/V-T must be reported, and results cannot be easily compared if the measurement methods are not the same.
- 出版日期2017-4
