The influence of arterial flow on capillary refill in pediatric lower extremity.

This study assesses the relationship between capillary refill time (CRT) and arterial blood flow (ABF) in the lower extremities of pediatric patients to determine if a correlation exists that would demonstrate CRT as an accurate means of monitoring tissue perfusion. The ABF and CRT were evaluated in 20 pediatric patients at four different pressures (0, (1/2) systolic blood pressure [SBP], SBP, and 1(1/2) SBP) using Doppler ultrasound and a stop-frame digital camera. While the mean ABF in the popliteal artery, dorsalis pedis, and posterior tibialis decreased dramatically with the increased pressure, the mean CRT showed only minor increases in duration. The >90% decrease in ABF between 0 and 1(1/2) SBP correlated to only a 0.8925-second change in CRT. Thus, at significantly decreased rates of blood flow, a possible inverse relationship exist between ABF and CRT in the lower extremities of this pediatric population. However, the change in CRT correlating to the decrease in ABF is too small to be considered practically useful for clinically monitoring tissue perfusion.