US 12,220,254 B2
Estimating hydration using capillary refill time
Richard Howard Weitzel, Aloha, OR (US); Steven D. Baker, Beaverton, OR (US); Richard Allen Sunderland, Clive, IA (US); Matthew Lee Hansen, Portland, OR (US); and David Clark Sheridan, Beaverton, OR (US)
Assigned to Welch Allyn, Inc., Skaneateles Falls, NY (US); and Oregon Health & Science University, Portland, OR (US)
Filed by Welch Allyn, Inc., Skaneateles Falls, NY (US)
Filed on May 2, 2022, as Appl. No. 17/661,589.
Application 17/661,589 is a continuation of application No. 15/405,412, filed on Jan. 13, 2017, granted, now 11,344,254.
Claims priority of provisional application 62/286,043, filed on Jan. 22, 2016.
Claims priority of provisional application 62/324,941, filed on Apr. 20, 2016.
Prior Publication US 2022/0313160 A1, Oct. 6, 2022
Int. Cl. A61B 5/00 (2006.01); A61B 5/01 (2006.01); A61B 5/024 (2006.01)
CPC A61B 5/4875 (2013.01) [A61B 5/0053 (2013.01); A61B 5/0059 (2013.01); A61B 5/01 (2013.01); A61B 5/02422 (2013.01); A61B 5/6826 (2013.01); A61B 5/6829 (2013.01); A61B 5/7278 (2013.01); A61B 5/742 (2013.01); A61B 5/746 (2013.01)] 20 Claims
OG exemplary drawing
 
18. A method for determining capillary refill time from a waveform, comprising steps of:
measuring, using a pressure sensor, a blanching pressure;
comparing, using a processor, the blanching pressure to a target pressure;
controlling, using the processor, a pressure system to stop increasing the blanching pressure when the target pressure is achieved;
analyzing, using the processor, signal characteristics of the waveform indicating fluctuations in an intensity of light passed through or reflected from tissue during a capillary refill test to determine a time when the blanching pressure is applied;
analyzing, using the processor, the signal characteristics of the waveform to determine a time when the blanching pressure is released;
analyzing, using the processor, the signal characteristics of the waveform that existed prior to the time when the blanching pressure is applied to determine a baseline response;
analyzing, using the processor, the signal characteristics of the waveform after the blanching pressure is released to determine a time when the waveform has returned to baseline; and
calculating, using the processor, a capillary refill time by subtracting the time when the blanching pressure is released from the time when the waveform has returned to the baseline.