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Updated: Jun 5, 2026

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb
Published on: December 2, 2017
A normal capillary refill time of ≤ 2 seconds is associated with superior vena cava oxygen saturations of ≥ 70%
Patricia L Raimer1, Yong Y Han, Monica S Weber
1Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, C.S. Mott Children's Hospital, Ann Arbor, MI, USA.
Objective:
To test the hypothesis that a normal capillary refill time (CRT) ≤ 2 seconds is associated with superior vena cava oxygen saturation (ScvO₂) ≥ 70% in critically ill children.
Study Design:
Two-year, prospective study in a tertiary-level pediatric intensive care unit. Whenever ScvO₂ measurements were obtained, central (forehead/sternum) and peripheral (finger/toe) CRTs were concomitantly assessed.
Results:
Central and peripheral CRTs ≤ 2 seconds were both associated with ScvO₂ ≥ 70% (P < .01). Sensitivity/specificity analyses revealed that central CRT ≤ 2 seconds demonstrated a sensitivity of 84.4%, specificity of 71.4%, positive predictive value of 93.1%, and negative predictive value of 50.0% in predicting ScvO₂ ≥ 70%. Peripheral CRT ≤ 2 seconds had a sensitivity of 71.9%, specificity of 85.7%, positive predictive value of 95.8%, and negative predictive value of 40.0% in predicting ScvO₂ ≥ 70%.
Conclusions:
A normal CRT ≤ 2 seconds can be predictive of ScvO₂ ≥ 70%. Our study corroborates the recommendations of the Pediatric Advanced Life Support curricula targeting a normal CRT ≤ 2 seconds as a therapeutic endpoint for goal-directed shock resuscitation. This clinical target remains particularly relevant in community hospitals when the ability to obtain central venous catheter access may be limited and ScvO₂ data unavailable.
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