[Progress in the protocolized application of automated capillary refill time in septic shock resuscitation]

Resuscitation in septic shock has traditionally relied mainly on macrocirculatory indicators, such as mean arterial pressure and urine output, and metabolic indicators, such as lactate. However, macrocirculation and microcirculation/peripheral perfusion are often dissociated. In addition, lactate decline may be delayed, or lactate may be elevated for reasons unrelated to hypoperfusion, owing to impaired clearance and catecholamine-related metabolic alterations. Capillary refill time (CRT), a classic bedside sign, can reflect cutaneous microcirculatory reperfusion to some extent. In recent years, automated capillary refill time (aCRT), based on standardized compression and objective optical signal analysis, has reduced operator-related variability and enabled frequent trend monitoring, thereby providing a technical basis for the protocolized use of peripheral perfusion endpoints. An international multicenter randomized controlled trial comparing CRT-guided with lactate-guided resuscitation showed that CRT-targeted resuscitation was associated with less organ dysfunction at 72 hours in patients with septic shock, and a subsequent Bayesian reanalysis indicated a high probability of benefit. More recently, an individualized hemodynamic resuscitation strategy has integrated CRT endpoints with hemodynamic phenotyping, suggesting that combining peripheral perfusion endpoints with phenotype-guided interventions may improve the individualization and generalizability of resuscitation strategies. This review systematically summarizes the physiological basis of CRT and its automated measurement, key issues in measurement and standardization, and pivotal clinical evidence. It further proposes a closed-loop workflow centered on "withholding further fluid administration and triggering reassessment", aiming to facilitate the translation of aCRT into an actionable, quality-controlled, and traceable bedside decision-support tool in emergency and critical care practice.