Discordance Between Capillary Refill Time and Oxygen Extraction Ratio in Septic Shock

Condition(s) studied

Investigational drug(s) / intervention(s)

Capillary refill time (CRT): Non-invasive, standardized bedside measurement of capillary refill time on the right index finger.

Oxygen extraction ratio (O₂ER) assessment: Oxygen extraction ratio calculated as (SaO₂ - ScvO₂)/SaO₂ from routinely obtained arterial and central venous blood gases.

Study summary

In septic shock, restoring large-vessel (macrocirculatory) perfusion-reflected by a normal capillary refill time (CRT)-does not always mean that oxygen use at the tissue level has recovered. This mismatch, sometimes called loss of hemodynamic coherence, may be detectable by comparing CRT with the oxygen extraction ratio (O₂ER), a marker of how much oxygen the tissues are extracting from the blood. Patients whose CRT has normalized but whose O₂ER remains abnormal-either too high (suggesting oxygen delivery that is insufficient for demand) or too low (suggesting microcirculatory shunting)-are considered to have a "discordant" perfusion phenotype.

This prospective, single-center, observational cohort study aims to determine how often this CRT-O₂ER discordance occurs at the 6th hour of resuscitation in adult patients with septic shock, and whether it is associated with 28-day mortality. Approximately 100 consecutive adult patients diagnosed with septic shock (with pre-existing central venous and arterial catheters) will be followed. Clinical and laboratory measurements-including CRT, O₂ER, lactate, mottling score, and organ dysfunction scores-will be recorded at hours 0, 6, 12, and 24, with the main phenotype grouping performed at hour 6. The study is purely observational: CRT is a painless, non-invasive bedside measurement, and O₂ER is calculated from blood gas samples already drawn as part of routine care, so no additional interventions or blood draws are performed for research purposes.

Eligibility

Primary outcome measure(s)

• Prevalence of the discordant CRT-O₂ER phenotype — At hour 6 of resuscitation (6 hours after vasopressor initiation)
  Proportion of patients classified as having a discordant perfusion phenotype (normalized CRT ≤3 s with an abnormal O₂ER, i.e., \>30% or \<20%; combined Group 2a + Group 2b) at hour 6, reported with 95% confidence interval.
• 28-day all-cause mortality — 28 days from Hour 0 (vasopressor initiation)
  All-cause mortality at 28 days, and its association with the hour-6 perfusion phenotype.

Trial sites (1)

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