Sublingual capnometry: A new noninvasive measurement for diagnosis and quantitation of severity of circulatory shock

Objective: To investigate the feasibility and predictive value of sublingua l Pco(2) (P(SL)co(2)) measurements as a noninvasive and early indicator of systemic perfusion failure. Design:A prospective, criterion study. Setting: Emergency department and medical and surgical intensive care units of an urban community medical center. Participants and Patients: Five normal human volunteers and 46 patients wit h acutely life-threatening illness or injuries. Interventions: Intra-arteri al or automated cuff blood pressure and arterial blood lactate (LAC) were m easured concurrently with P(SL)co(2). Results: P(SL)co(2) in five healthy volunteers was 45.2 +/- 0.7 mm Hg (mean +/- so). Twenty-six patients with physical signs of circulatory shock and LAC >2.5 mmol/L had a P-SL co(2) of 81 +/- 24 mm Hg. This contrasted with p atients admitted without clinical signs of shock and LAC of <2.5 mmol/L who had a P(SL)co(2) of 53 +/- 8 mm Hg (p < .001), The initial P(SL)co(2) of 1 2 patients who died before recovery from shock was 93 +/- 27 mm Hg, and thi s contrasted with 58 +/- 11 mm Hg (p < .001) in hospital survivors, Increas es in P(SL)co(2) were correlated with increases in LAC (r(2) = .84; p < .00 1). When P(SL)co(2) exceeded a threshold of 70 mm Hg, its positive predicti ve value for the presence of physical signs of circulatory shock was 1.00, When it was <70 mm tig, it predicted survival with a predictive value of 0. 93, Conclusion: P(SL)co(2) may serve as a technically simple and noninvasive cl inical measurement for the diagnosis and estimation of the severity of circ ulatory shock states.