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- Jon-Émile S Kenny, Igor Barjaktarevic, Andrew M Eibl, Matthew Parrotta, Bradley F Long, Joseph K Eibl, and Frederic Michard.
- Health Sciences North Research Institute, Sudbury ON, Canada.
- Crit Care Explor. 2020 Jan 1; 2 (1): e0072.
ObjectivesDetecting instantaneous stroke volume change in response to altered cardiac preload is the physiologic foundation for determining preload responsiveness.DesignProof-of-concept physiology study.SettingResearch simulation laboratory.SubjectsTwelve healthy volunteers.InterventionsA wireless continuous wave Doppler ultrasound patch was used to measure carotid velocity time integral and carotid corrected flow time during a squat maneuver. The Doppler patch measurements were compared with simultaneous stroke volume measurements obtained from a noninvasive cardiac output monitor.Measurements And Main ResultsFrom stand to squat, stroke volume increased by 24% while carotid velocity time integral and carotid corrected flow time increased by 32% and 9%, respectively. From squat to stand, stroke volume decreased by 13%, while carotid velocity time integral and carotid corrected flow time decreased by 24% and 10%, respectively. Both changes in carotid velocity time integral and corrected flow time were closely correlated with changes in stroke volume (r 2 = 0.81 and 0.62, respectively). The four-quadrant plot found a 100% concordance rate between changes in stroke volume and both changes in carotid velocity time integral and changes in corrected flow time. A change in carotid velocity time integral greater than 15% predicted a change in stroke volume greater than 10% with a sensitivity of 95% and a specificity of 92%. A change in carotid corrected flow time greater than 4% predicted a change in stroke volume greater than 10% with a sensitivity of 90% and a specificity of 92%.ConclusionsIn healthy volunteers, both carotid velocity time integral and carotid corrected flow time measured by a wireless Doppler patch were useful to track changes in stroke volume induced by a preload-modifying maneuver with high sensitivity and specificity.Copyright © 2020 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.
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