Transcutaneous oxygen pressure-related variables as noninvasive indicators of low lactate clearance in sepsis patients after resuscitation

The transcutaneous oxygen challenge test (OCT) is associated with central venous oxygen saturation and cardiac output index, and has predictive value for prognosis. Whether the change of transcutaneous oxygen pressure (P_tcO₂)-related variables can reflect lactate clearance in sepsis patients is worth studying. We conducted a prospective observational study of 79 patients with sepsis or septic shock in the ICU. Immediately after enrollment, P_tcO₂ monitoring was continuously performed for 6 h. The OCT was performed at enrollment (T0) and the sixth hour (T6). The correlation between lactate clearance and P_tcO₂-related variables such as P_tcO₂ at T6, ΔP_tcO₂ (P_tcO₂ at T6 − P_tcO₂ at T0), ΔP_tcO₂ index (P_tcO₂/PaO₂ at T6 − P_tcO₂/PaO₂ at T0), 10 OCT [(P_tcO₂ after 10 min on FiO₂ of 1.0) − (P_tcO₂ at baseline)], Δ10 OCT (10 OCT at T6 − 10 OCT at T0) was analyzed. The difference of P_tcO₂-related variables was compared between the high and low lactate clearance groups. P_tcO₂ at T6 (r = 0.477, p < 0.001), ΔP_tcO₂ (r = 0.592, p < 0.001), ΔP_tcO₂ index (r = 0.553, p < 0.001) and Δ10 OCT (r = 0.379, p = 0.001) were significantly correlated with the lactate clearance. To discriminate low lactate clearance, the area under the ROC curve was largest for ΔP_tcO₂, which was 0.804. P_tcO₂ at T6, P_tcO₂ index, ΔP_tcO₂, ΔP_tcO₂ index and Δ10 OCT were significantly different between the two different lactate clearance groups. Low lactate clearance in the initial 6 h of resuscitation of septic shock was associated to lower improvements in P_tcO₂-related variables.