Transcutaneous arterial carbon dioxide pressure monitoring in critically ill adult patients.
OBJECTIVE
To evaluate the accuracy of transcutaneous PCO(2) (PtcCO(2)) as a surrogate for arterial PCO(2) (PaCO(2)) in a cohort of adult critically ill patients in a medical intensive care unit (ICU).


METHODS
Prospective observational study comparing paired measures of transcutaneous and arterial PCO(2).


METHODS
A 26-bed medical ICU.


METHODS
Fifty ICU patients monitored with a SenTec Digital Monitor placed at the ear lobe over prolonged periods.


RESULTS
A total of 189 paired PCO(2) measures were obtained. Twenty-one were excluded from analysis, because profound skin vasoconstriction was present (PCO(2) bias =-10.8+/-21.8 mmHg). Finally, 168 were analysed, including 137 obtained during mechanical ventilation and 82 under catecholamine treatment. Body temperature was below 36 degrees C for 27 measurements. Mean duration of monitoring was 17+/-17 h. The mean difference between PaCO(2) and PtcCO(2) was -0.2+/-4.6 mmHg with a tight correlation (R(2)=0.92, p>0.01). PCO(2) bias did not significantly change among three successive measurements. Changes in PaCO(2) and in PtcCO(2) between two blood samples were well correlated (R(2)=0.78, p>0.01). Variations of more than 8 mmHg in PtcCO(2) had 86% sensitivity and 80% specificity to correctly predict similar changes in PaCO(2) in the same direction. Catecholamine dose or respiratory support did not affect PtcCO(2) accuracy. Hypothermia has only a small effect on accuracy. No complication related to a prolonged use of the sensor was observed


CONCLUSIONS
Transcutaneous PCO(2) provides a safe and reliable trend-monitoring tool, provided there is no major vasoconstriction.
Rodriguez
Pablo
P
Faculté Médicine, Université Paris XII, 94010, Créteil Cedex, France.|Service de Réanimation Médicale et INSERM U 651, AP-HP, Hôpital Henri Mondor, 94010, Créteil Cedex, France.
Lellouche
François
F
Faculté Médicine, Université Paris XII, 94010, Créteil Cedex, France.|Service de Réanimation Médicale et INSERM U 651, AP-HP, Hôpital Henri Mondor, 94010, Créteil Cedex, France.
Aboab
Jerome
J
Faculté Médicine, Université Paris XII, 94010, Créteil Cedex, France.|Service de Réanimation Médicale et INSERM U 651, AP-HP, Hôpital Henri Mondor, 94010, Créteil Cedex, France.
Buisson
Christian Brun
CB
Faculté Médicine, Université Paris XII, 94010, Créteil Cedex, France.|Service de Réanimation Médicale et INSERM U 651, AP-HP, Hôpital Henri Mondor, 94010, Créteil Cedex, France.
Brochard
Laurent
L
Faculté Médicine, Université Paris XII, 94010, Créteil Cedex, France. laurent.brochard@hmn.aphp.fr.|Service de Réanimation Médicale et INSERM U 651, AP-HP, Hôpital Henri Mondor, 94010, Créteil Cedex, France. laurent.brochard@hmn.aphp.fr.
D000328:Adult; D000704:Analysis of Variance; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D002245:Carbon Dioxide / Q000097:blood*; D016638:Critical Illness; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve
D002245:Carbon Dioxide