Arterial blood lactate is a reliable indicator of tissue oxygen debt and is of value in expressing the degree and prognosis of circulatory failure. Compared with arterial measurement, capillary lactate measurement is easier, faster, cheaper and lowers the incidence of arterial puncture complications. Capillary lactate measurement has been already validated to assess fetal well-being. The aim of this study was to compare arterial and capillary lactate in adult shocked patients.
Consecutive shocked patients hospitalized in a university hospital surgical ICU were simultaneously tested for arterial and capillary lactate measurements. Arterial lactate was measured by the usual method described by Marbach and Weil, capillary lactate was measured using a micromethod device (Lactate Pro* LT1710; Arkray, KGK, Japan). Lactate levels were compared by linear regression, calculation of Pearson's correlation coefficient R2 and using a Bland–Altman plot.
In total, 60 simultaneous measurements of capillary and arterial blood lactate concentrations were performed in 16 patients with shock. A good linear correlation was found between capillary lactate (CapL) and arterial lactate (ArtL) concentrations: CapL = 0.85ArtL + 1.61; r = 0.8 (P < 0.0001). The mean difference was 0.78 ± 2.3 mmol/l. See Figure 1.
These preliminary findings suggest that capillary lactate values could be used to assess the severity and guide therapy during shock.