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Abstract
Background Capillary refill time (CRT) is widely used in paediatrics to assess cardiovascular status, especially during the early phase of shock when skin perfusion is reduced, but is prone to marked variability (Pickard 2011). CRT is used in early warning scores aimed at identifying and quantifying severity of illness and effectiveness of resuscitation efforts (APLS 2011). CRT is one of the most sensitive predictors of dehydration and bacterial infection in children, and it correlates with markers of end organ perfusion (Tibby 1999, Craig 2010). Automating CRT using photoplethysmography (PPG) with a pressure application system may improve its accuracy and reliability.
Aim Establish if a green light PPG and a pressure application system could detect an increase in CRT after skin cooling.
Methods Healthy children (aged 5–18 years) underwent selective arm cooling as a model of reduced skin blood flow through the microcirculation (Roustit and Cracowski 2013). An automated green light PPG CRT device was attached to their forearm and their arm was then placed into a refrigeration device at 4°C for 20 min. Using 7 min rolling averages, the trough (early phase) and peak (late phase) CRT values were compared. Ethical approval was given.
Results Participants (n = 16) demonstrated a significant increase in CRT (as assessed by green PPG) in 15 of the 16 cases (P < 0.001)(see Figure).
Conclusions It is feasible to measure changes in the microcirculation of children using an automated device that mimics CRT testing. Further work in clinical settings is needed to establish if this has clinical utility.
