Cutaneous Ear Lobe P co 2 at 37°C To Evaluate Microperfusion in Patients With Septic Shock

Background Tissue hypercarbia is related to hypoperfusion and microcirculatory disturbances in patients with septic shock. Transcutaneous Pco 2 devices using a heated sensor to arterialize the tissue have been used as an alternative method for estimation of Paco 2 . This study investigates whether a cutaneous sensor attached to an ear lobe and regulated to 37°C could be used to measure cutaneous Pco 2 (Pcco 2 ) and evaluate microperfusion in patients with septic shock. Methods Fifteen stable patients in an ICU were studied as a control group. Forty-six patients with septic shock who were ventilated were enrolled as the study group. The difference of the gradients between Pcco 2 and Paco 2 (Pc-aco 2 ) and between Pcco 2 and end-tidal Pco 2 (Pc-etco 2 ) were evaluated for 36 h. Variations of the Pc-aco 2 and Pc-etco 2 during fluid challenge were compared with microcirculatory skin blood flow (mBFskin) assessed by laser Doppler flowmetry. Results The baseline levels for Pc-aco 2 and Pc-etco 2 were significantly higher in the patients with septic shock than in the control group (14.8 [12.6] vs 6 [2.7] mm Hg and 25 [16.3] vs 9 [3.8] mm Hg, P 2 and Pc-etco 2 for the surviving patients with septic shock decreased significantly compared with the nonsurvivors ( P 2 > 16 mm Hg and a Pc-etco 2 > 26 mm Hg were related to poor outcome. Pc-aco 2 and Pc-etco 2 variations during fluid challenge were inversely correlated with changes in mBFskin ( r 2 = 0.7). Conclusions Ear lobe cutaneous Pco 2 at 37°C represents a noninvasive technique to assess tissue Pco 2 measurement. Pc-aco 2 and Pc-etco 2 were related to outcome and provide continuous information on microperfusion in patients with septic shock.