Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Intensive Care Medicine Experimental

David C. Mackenzie¹  Igor Barjaktarevic²  Jon-Émile S. Kenny³  Matthew Parrotta³  Andrew M. Eibl³  Bradley F. Long⁴  Joseph K. Eibl⁴ 

[1] Department of Emergency Medicine, Maine Medical Center, Portland, ME, USA;Tufts University School of Medicine, Boston, MA, USA;Division of Pulmonary and Critical Care, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA;Health Sciences North Research Institute, P3E 2H2, Sudbury, ON, Canada;Health Sciences North Research Institute, P3E 2H2, Sudbury, ON, Canada;Northern Ontario School of Medicine, Sudbury, ON, Canada;

关键词: Carotid artery;    Corrected flow time;    Fluid responsiveness;    Hemodynamics;    Stroke volume;   

DOI  :  10.1186/s40635-020-00339-7

来源: Springer

【 摘 要 】

BackgroundChange of the corrected flow time (Ftc) is a surrogate for tracking stroke volume (SV) in the intensive care unit. Multiple Ftc equations have been proposed; many have not had their diagnostic characteristics for detecting SV change reported. Further, little is known about the inherent Ftc variability induced by the respiratory cycle.Materials and methodsUsing a wearable Doppler ultrasound patch, we studied the clinical performance of 11 Ftc equations to detect a 10% change in SV measured by non-invasive pulse contour analysis; 26 healthy volunteers performed a standardized cardiac preload modifying maneuver.ResultsOne hundred changes in cardiac preload and 3890 carotid beats were analyzed. Most of the 11 Ftc equations studied had similar diagnostic attributes. Wodeys’ and Chambers’ formulae had identical results; a 2% change in Ftc detected a 10% change in SV with a sensitivity and specificity of 96% and 93%, respectively. Similarly, a 3% change in Ftc calculated by Bazett’s formula displayed a sensitivity and specificity of 91% and 93%. FtcWodey had 100% concordance and an R2 of 0.75 with change in SV; these values were 99%, 0.76 and 98%, 0.71 for FtcChambers and FtcBazetts, respectively. As an exploratory analysis, we studied 3335 carotid beats for the dispersion of Ftc during quiet breathing using the equations of Wodey and Bazett. The coefficient of variation of Ftc during quiet breathing for these formulae were 0.06 and 0.07, respectively.ConclusionsMost of the 11 different equations used to calculate carotid artery Ftc from a wearable Doppler ultrasound patch had similar thresholds and abilities to detect SV change in healthy volunteers. Variation in Ftc induced by the respiratory cycle is important; measuring a clinically significant change in Ftc with statistical confidence requires a large sample of beats.

【 授权许可】

CC BY