Effect of Paco₂ variation on standard base excess value in critically ill patients

Abstract 

Purpose

The aim of this study was to investigate the impact of acute Paco₂ temporal variation on the standard base excess (SBE) value in critically ill patients.

Methods

A total of 265 patients were prospectively observed; 158 were allocated to the modeling group, and 107 were allocated to the validation group. Two models were developed in the modeling group (one including and one excluding Paco₂ as a variable determinant of SBE), and both were tested in the validation group.

Results

In the modeling group, the mathematical model including SIDai, SIG, l-lactate, albumin, phosphate, and Paco₂ had a predictive superiority in comparison with the model without Paco₂ (R² = 0.978 and 0.916, respectively). In the validation group, the results were confirmed with significant F change statistics (R² change = 0.059, P < .001) between the model with and without Paco₂. A high correlation (R = 0.99, P < .001) and agreement (bias = −0.25 mEq/L, limits of agreement 95% = −0.72 to 0.22 mEq/L) were found between the model-predicted SBE value and the SBE calculated using the Van Slyke equation.

Conclusions

Acute Paco₂ temporal variation is related to SBE changes in critically ill patients.

Keywords: Acidosis, Base excess, Outcomes, Critical care, Strong ion gap