Sublingual capnography: a clinical validation study.
OBJECTIVE
To compare sublingual PCO(2) (PslCO(2)) measurements with gastric intramucosal PCO(2) (PimCO(2)) as well as with the traditional indexes of tissue oxygenation in hemodynamically unstable ICU patients.


METHODS
A prospective, validation study.


METHODS
The medical and coronary ICUs of a community teaching hospital.


METHODS
Consecutive patients with severe sepsis, septic shock, or cardiogenic shock requiring pulmonary artery catheterization for hemodynamic management.


METHODS
During the first 24 h of ICU admission, the PslCO(2), PimCO(2), and blood lactate concentrations as well conventional hemodynamic and oxygenation parameters were recorded every 4 to 6 h. The PslCO(2)-PaCO(2) and PimCO(2)-PaCO(2) differences were used as indexes of tissue dysoxia. These variables were correlated with each other as well as with the traditional markers of tissue oxygenation.


RESULTS
Seventy-six data sets were obtained on 22 patients. Fifteen patients had severe sepsis/septic shock, and 7 patients did not have sepsis. A patient with ischemic bowel who had a large PimCO(2)-PslCO(2) difference (60.2 mm Hg) was excluded. The initial PslCO(2) and PimCO(2) measurements were 43.5 +/- 10.4 mm Hg and 42.8 +/- 10.9 mm Hg, respectively (correlation coefficient [r] of 0.86; p < 0.001). The mean PslCO(2) and PimCO(2) for the entire data set were 48.0 +/- 13.4 mm Hg and 46.1 +/- 12.3 mm Hg, respectively (r = 0.78; p < 0.001). Ten patients died. The initial PslCO(2)-PaCO(2) difference was 9.2 +/- 5.0 mm Hg in the survivors and 17.8 +/- 11.5 mm Hg in the nonsurvivors (p = 0.04). The initial PimCO(2)-PaCO(2) difference was 8.4 +/- 4.8 mm Hg in the survivors and 16.1 +/- 13.7 mm Hg in the nonsurvivors (p = 0.08, not significant). The initial PslCO(2)-PaCO(2) difference correlated with the initial mixed venous-arterial CO(2) gradient (r = 0.66; p = 0.001), but correlated poorly with the initial blood lactate concentration (r = 0.38), mixed venous PO(2) (r = 0.05), and systemic oxygen delivery (r = - 0.39).


CONCLUSIONS
In this study, sublingual capnometry yielded measurements that correlated well with those of gastric tonometry. PslCO(2) may serve as a technically simple and noninvasive clinical measurement of tissue dysoxia in critically ill and injured patients.
Marik
P E
PE
Critical Care Medicine, The Mercy Hospital of Pittsburgh, Pittsburgh, PA 15219-5166, USA. pmarik@zbzoom.net
D000138:Acidosis / Q000175:diagnosis*; D000368:Aged; D019296:Capnography; D016638:Critical Illness; D005260:Female; D005745:Gastric Acidity Determination; D006439:Hemodynamics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011446:Prospective Studies; D018805:Sepsis / Q000503:physiopathology*; D012770:Shock, Cardiogenic / Q000503:physiopathology*; D012772:Shock, Septic / Q000503:physiopathology*