Can Transcutaneous CO2 Tension Be Used to Calculate Ventilatory Dead Space? A Pilot Study.
Dead space fraction (V d/V t) measurement performed using volumetric capnography requires arterial blood gas (ABG) sampling to estimate the partial pressure of carbon dioxide (PaCO2). In recent years, transcutaneous capnography (PtcCO2) has emerged as a noninvasive method of estimating PaCO2. We hypothesized that PtcCO2 can be used as a substitute for PaCO2 in the calculation of V d/V t. In this prospective pilot comparison study, 30 consecutive postcardiac surgery mechanically ventilated patients had V d/V t calculated separately using volumetric capnography by substituting PtcCO2 for PaCO2. The mean V d/V t calculated using PaCO2 and PtcCO2 was 0.48 ± 0.09 and 0.53 ± 0.08, respectively, with a strong positive correlation between the two methods of calculation (Pearson's correlation = 0.87, p < 0.05). Bland-Altman analysis showed a mean difference of -0.05 (95% CI: -0.01 to -0.09) between the two methods. PtcCO2 measurements can provide a noninvasive means to measure V d/V t, thus accessing important physiologic information and prognostic assessment in patients receiving mechanical ventilation.
Section of Pulmonary, Critical Care and Sleep Medicine, Bridgeport Hospital, Yale New Haven Health, 267 Grant Street, Bridgeport, CT 06610, USA.
Pradeep H
0000-0002-6117-3322
PH
Lakshminarayana
Section of Pulmonary, Critical Care and Sleep Medicine, Bridgeport Hospital, Yale New Haven Health, 267 Grant Street, Bridgeport, CT 06610, USA.
Adiba A
AA
Geeti
Yale Cardiac Surgery, Bridgeport Hospital, 267 Grant Street, Bridgeport, CT 06610, USA.
Umer M
UM
Darr
Section of Pulmonary, Critical Care and Sleep Medicine, Bridgeport Hospital, Yale New Haven Health, 267 Grant Street, Bridgeport, CT 06610, USA.
David A
DA
Kaufman
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