Evaluation of transcutaneous CO2 responses following acute changes in PaCO2 in healthy subjects.
OBJECTIVE
Transcutaneous blood gas-monitoring systems with miniaturized SpO(2) (peripheral blood oxygen saturation)/PCO(2) combined sensors (TOSCATM) have been widely used. There are no reports of the inter- and intra-individual variability in transcutaneous measurements of PaCO(2) (PtcCO(2)) in response to acute progressive changes in PaCO(2). This study examined inter- and intra-individual variability of PtcCO(2) measurements under semi-steady-state conditions, and characterized the behaviour of PtcCO(2) in response to acute progressive changes in PaCO(2).


METHODS
Subjects breathed mixed gases through a mouthpiece connected to an automatic arterial blood gas controller. Using end-tidal PCO(2) and PO(2) as guides, PaCO(2) was controlled to increase and/or decrease between baseline and > or = 60 mm Hg, in a stepwise (n = 9) or progressive fashion (n = 6). Arterial blood was sampled when needed.


RESULTS
Intra-individual correlation coefficients between PtcCO(2) and PaCO(2) were excellent in all subjects (0.971-0.989); however, the slope of the regression line varied among subjects (1.040-1.335). Bias and limits of agreement (+/- 2 SD from bias) between PtcCO(2) and PaCO(2) were -1.8 mm Hg and -7.7 to 4.1 mm Hg. Changes in PtcCO(2) in response to acute progressive changes in PaCO(2) also varied among subjects.


CONCLUSIONS
The PtcCO(2) measurement system allows reliable estimation of PaCO(2) in a given subject. However, caution is needed when comparing absolute values between subjects or when acute changes in PaCO(2) occur.
Fuke
Satoshi
S
First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Miyamoto
Kenji
K
Ohira
Hiroshi
H
Ohira
Megumi
M
Odajima
Nao
N
Nishimura
Masaharu
M
D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D001944:Breath Tests / Q000379:methods*; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D045853:Exhalation / Q000502:physiology*; D006801:Humans; D015588:Observer Variation; D010100:Oxygen / Q000378:metabolism; D011659:Pulmonary Gas Exchange / Q000502:physiology; D055815:Young Adult
D002245:Carbon Dioxide; D010100:Oxygen