Noninvasive carbon dioxide monitoring during neurosurgical procedures in adults: end-tidal versus transcutaneous techniques.
BACKGROUND
We prospectively compared transcutaneous (TC) versus end-tidal (ET) carbon dioxide monitoring during neurosurgical procedures in adults.


METHODS
After calibration and an equilibration time for the TC-CO2 monitor, arterial blood gas (ABG) values were obtained as clinically indicated. The PaCO2 values were compared with the values recorded by the noninvasive monitors (TC and ET).


RESULTS
The ET-CO2 to PaCO2 difference was 6.1 +/- 5.6 mm Hg, and the TC-CO2 to PaCO2 difference was 3.7 +/- 2.9 mm Hg. The difference between the PaCO2 and ET-CO2 was 3 mm Hg or less in 17 of 57 values, while the difference between the PaCO2 and TC-CO2 was 3 mm Hg or less in 35 of 57 values. Linear regression analysis of ET-CO2 versus PaCO2 revealed a slope of 0.381 +/- 0.007. Linear regression analysis of TC-CO2 versus PaCO2 revealed a slope of 1.17 +/- 0.008.


CONCLUSIONS
Transcutaneous CO2 monitoring provides a more accurate estimate of PaCO2 than ET-CO2 monitoring during neurosurgical procedures.
McBride
D Scott
DS
Department of Child Health, University of Missouri, Columbia 65212, USA.
Johnson
Joel O
JO
Tobias
Joseph D
JD
D000293:Adolescent; D000328:Adult; D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D019635:Neurosurgical Procedures; D010092:Oximetry; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013990:Tidal Volume