Using peripheral perfusion index and venous-to-arterial CO(2) difference/arterial-central venous O(2) difference ratio to assess lactate clearance in septic patients after resuscitation

Abstract

Objective: The relationship of venous-to-arterial CO(2) difference(Pv-aCO(2))/arterial-central venous O(2) difference (Ca-vO(2)) ratio, peripheral perfusion index(PI) and lactate clearance(LC) were investigated during resuscitation in septic patients. And, the meaning of the combination PI and Pv-aCO(2)/Ca-vO(2) ratio to interpret incoherence of lactate clear was explored. Methods: The patients with sepsis were prospectively observed, who admitted to critically care medicine department of Peking Union Medical College Hospital. The hemodynamic parameters, simultaneous arterial and central venous blood gas analysis and PI were obtained at the enrollment (T0) and 8 hours (T8) during resuscitation. The lactate clearance was defined as 8h-LC≥10% and non-lactate clearance was defined as 8h-LC ≤ 10%. Additionally, the patients were divided as three sub-groups according to the PI value at T8: the normalized PI group with PI≥1.4,the mild impaired PI with 1.4<PI<0.6 and severe impaired PI with PI≤0.6. Results: A total of 84 patients were enrolled in this study. There was no significant difference in Pv-aCO(2)/Ca-vO(2) ratio in the three groups. However, the PI≤0.6 group had a significantly higher Pv-aCO(2) than other groups. Moreover, the patients with non-lactate clearance (13/32) had a higher Pv-aCO(2)/Ca-vO(2) ratio than the patients with lactate clearance in PI≥1.4 group (1.9±0.7 vs. 1.3±1.0, P=0.01). Multivariate analysis showed both Pv-aCO(2)/Ca-vO(2) ratio [Exp(B) 2.235, 95% CI 1.232-4.055, P=0.008] and acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) [Exp (B) 1.087, 95%CI 1.022-1.156, P=0.008] were independent risk factor of non-lactate clearance. 8h-PI was significantly negative correlated with the 8 h Pv-aCO(2) gap (r=-0.311, P=0.004), but not significantly with Pv-aCO(2)/Ca-vO(2) ratio (r=-0.094, P=0.385). Conclusions: Both high Pv-aCO(2)/Ca-vO(2) ratio and low PI were related to non-lactate clearance after resuscitation in sepsis. Combined PI and Pv-aCO(2)/Ca-vO(2) ratio could interpret incoherence of latacte clearance after resuscitation.