Multimodal assessment of peripheral perfusion in critically ill patients: a pilot study

Impaired peripheral perfusion is linked to poor outcomes in critically ill patients, but the relationships among common bedside assessment tools remain unclear. This study aimed to evaluate whether these parameters provide overlapping or complementary prognostic information across ICU subgroups. Adult ICU patients with an expected stay ≥ 3 days were included. On day 1, six peripheral perfusion parameters were simultaneously measured: Peripheral Perfusion Index (PPI), Mottling Score (MS), Capillary Refill Time (CRT), central-to-peripheral temperature gradient (ΔT), Skin Blood Flow at basal temperature (SBF BT ), and forearm tissue oxygenation (rSO₂). The primary outcome was correlation between parameters; secondary outcomes included subgroup consistency and associations with ICU mortality. Fifty-five patients were included (median age 64; 65.5% male). Circulatory shock (36.4%) was the leading admission cause, followed by acute brain injury (ABI; 29.1%) and acute respiratory failure (ARF; 25.4%). Strong correlations were found between PPI, CRT, SBF BT , and ΔT, while rSO₂ showed no significant associations. Correlations were strongest in circulatory shock, weaker in ABI and ARF subgroups. CRT had the highest predictive value for ICU mortality (AUC = 0.75, p = 0.007), followed by MS (AUC = 0.72), SBF BT , and PPI. ΔT showed limited performance, and rSO₂ was the weakest predictor. Most bedside peripheral perfusion parameters were strongly interrelated, particularly PPI, SBF BT , and ΔT. In contrast, rSO₂ appeared poorly correlated and less predictive. CRT emerged as the most reliable marker of ICU mortality.