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The following is a summary of “Relationship between skin microvascular blood flow and capillary refill time in critically ill patients,” published in the February 2025 issue of Critical Care by Morin et al.
Researchers conducted a retrospective study to explore the relationship between capillary refill time (CRT) and skin blood flow (SBF) as predictors of mortality in individuals with critical illness.
They performed a study at a tertiary teaching hospital, including all individuals over 18 years old admitted to the intensive care unit (ICU) with circulatory failure and measurable CRT and SBF was assessed using laser Doppler flowmetry, and CRT was measured at the fingertip at T0 (within 48 hours of admission) and T1 (4 to 6 hours later). Spearman or Pearson’s correlation formulas were used for analysis.
The results showed that 50 individuals were included, with 54% admitted for sepsis. At baseline, the median CRT was 2.0 [1.1–3.9] seconds, and median SBF was 46 [20–184] Perfusion unit (PU). A strong correlation between SBF and CRT was found at baseline (R2 = 0.89; P < 0.0001, curvilinear), which remained consistent in septic (R2= 0.94; P = 0.0013) and non-septic individuals (R2 = 0.87; P < 0.0001), as well as with or without norepinephrine (R2 = 0.97; P = 0.0035; R2 = 0.92; P < 0.0001). Between T0 and T1, SBF changes correlated significantly with CRT changes (R2 = 0.34; P < 0.0001). The SBF was associated with tissue perfusion, such as arterial lactate levels (P = 0.02), but showed no correlation with cardiac output. Only survivors showed significant improvement in SBF between T0 and T1. The SBF was a strong predictor of 28-day mortality, with AUROC at T0 being 85% [95% CI [76–91]] and at T1 being 90% [95% CI [78–100]].
Investigators concluded that index CRT and SBF were correlated, providing evidence that CRT was a reliable marker of microvascular blood flow.
Source: ccforum.biomedcentral.com/articles/10.1186/s13054-025-05285-y
