Single breath tracing for carbon dioxide in septic patients with tissue hypoxia.
We investigated whether tissue hypoxia in sepsis produces substantial modifications of convective airway washout and consequently of CO2 transit time. Single breath tracing for carbon dioxide (SBT-CO2) was analysed in 18 ICU septic patients. Nine patients had tissue hypoxia events. Using the Hill formula, all tracings were analysed point by point to obtain the time required for CO2 to achieve 50% maximal value and the Fractional Expiratory Time 50 (FET0.5). Hypoxic patients FET0.5 and CO2 clearance were compared with non-hypoxic patients data. In hypoxic group CvCO2, CO2 clearance and FET0.5 values were higher than in non hypoxic group. During the recovery from hypoxia capnographic parameters did not differ from those recorded in the hypoxic period. CO2 clearance, but not FET0.5, correlated with arterial lactate and base excess either in hypoxic or in recovery period. In conclusion in septic patients tissue hypoxia influences CO2 elimination, modifying SB-CO2 tracing and lengthening FET0.5.
Zatelli
Renzo
R
Dept. of Anesthesia and Intensive Care, University of Ferrara, 44100 Ferrara, Italy.
D000368:Aged; D019296:Capnography / Q000379:methods*; D002245:Carbon Dioxide / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008875:Middle Aged; D018805:Sepsis / Q000378:metabolism*
D002245:Carbon Dioxide