Association between venous blood lactate levels and differences in quantitative capillary refill time

Capillary refill time has been widely adopted for clinical assessment of the circulatory status of patients in emergency settings. We previously introduced quantitative capillary refill time and found a positive association between longer quantitative capillary refill time and higher lactate levels in the intensive care units, but not in the emergency department. In this study, we aimed to identify a quantitative and clinically applicable index of circulatory status (ΔA _b) that can be measured with quantitative capillary refill time, then evaluated the linear association between this index and lactate levels in the emergency department.

We undertook a prospective single-center observational study at a university hospital from November 2015 to July 2016. We included 139 patients with endogenous diseases to test the association between quantitative capillary refill time, ΔA _b (measured with a pulse oximeter), and lactate levels.

ΔA _b was independently and significantly associated with high lactate levels (odds ratio [95% confidence interval]: 0.16 [0.05-0.45]).

We introduced ΔA _b, measured using quantitative capillary refill time, as a surrogate index of lactate levels to overcome the shortcomings of capillary refill time. We showed that ΔA _b is a feasible, non-invasive, and rapid assessment of patients with high lactate levels in emergency primary care settings. Future multicenter studies with a longitudinal design should be undertaken to verify our findings.