A wearable carotid Doppler tracks changes in the descending aorta and stroke volume induced by <scp>end‐inspiratory</scp> and <scp>end‐expiratory</scp> occlusion: A pilot study

Kenny, Jon‐Émile S.; Eibl, Andrew M; Parrotta, Matthew; Long, Bradley F; Eibl, Joseph K.

doi:10.1002/hsr2.190

Cited by 12 publications

(13 citation statements)

References 22 publications

(32 reference statements)

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“…These data are consistent with an earlier feasibility study first describing the DSI using a standardized Valsalva maneuver 7 ; the directional change in carotid Doppler metrics observed during simulated hemorrhage and transfusion was similar to a simulated end‐inspiratory, end‐expiratory occlusion test in healthy volunteers. 21 Although raising intra‐thoracic pressure during a Valsalva maneuver leads to central hypovolemia, the average SV reduction was only about 25% and relatively transient. To better study the effects of moderate‐to‐severe hypovolemia over many minutes, LBNP was employed for the present study.…”

Section: Discussionmentioning

confidence: 99%

“…We observed an “over‐shoot” in the VTI immediately upon release of LBNP in some volunteers, consistent with our observations in standardized Valsalva maneuvers. 21 This might reflect intra‐cerebral vasodilation that occurs with diminished cerebral perfusion. 22 Indeed, as an exploratory analysis, we compared the common carotid artery resistive index from the wearable Doppler across T1, T2, and T3.…”

Section: Discussionmentioning

confidence: 99%

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The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate‐to‐severe central hypovolemia during lower body negative pressure

et al. 2021

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Objective Moderate‐to‐severe hemorrhage is a life‐threatening condition, which is challenging to detect in a timely fashion using traditional vital signs because of the human body's robust physiologic compensatory mechanisms. Measuring and trending blood flow could improve diagnosis of clinically significant exsanguination. A lightweight, wireless, wearable Doppler ultrasound patch that captures and trends blood flow velocity could enhance hemorrhage detection. Methods In 11 healthy volunteers undergoing simulated hemorrhage and resuscitation during graded lower body negative pressure (LBNP) and release, we studied the relationship between stroke volume (SV) and common carotid artery velocity time integral (VTI) and corrected flow time (FTc). We assessed the diagnostic accuracy of 2 variations of a novel metric, the Doppler shock index (ie, the DSI VTI and DSI FTc ), at capturing moderate‐to‐severe central hypovolemia defined as a 30% reduction in SV. The DSI VTI and DSI FTc are calculated as the heart rate divided by either the VTI or FTc, respectively. Results A total of 17,822 cardiac cycles were analyzed across 22 LBNP protocols. The average SV reduction to the lowest tolerated LBNP stage was 40%; there was no clinically significant fall in the mean arterial pressure. Correlations between changing SV and the common carotid artery VTI and FTc were strong ( R 2 of 0.87, respectively) and concordant. The DSI VTI and DSI FTc accurately detected moderate‐to‐severe central hypovolemia with values for the area under the receiver operator curves of 0.96 and 0.97, respectively. Conclusion In a human model of hemorrhage and resuscitation, measures from a wearable Doppler ultrasound patch correlated strongly with SV and identified moderate‐to‐severe central hypovolemia with excellent diagnostic accuracy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate‐to‐severe central hypovolemia during lower body negative pressure

et al. 2021

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“…When using oesophageal Doppler, which has the same precision issues as cardiac ultrasound, the combination of EEO and end-inspiratory occlusion can also be used [ 50 ]. It was recently shown that a portable carotid Doppler tool could also track changes in stroke volume during combined end-inspiratory and end-expiratory occlusions [ 51 ], a result that is interesting but needs confirmation.…”

Section: End-expiratory Occlusion Testmentioning

confidence: 99%

Prediction of fluid responsiveness. What’s new?

Monnet

Shi

Teboul

2022

Ann. Intensive Care

122

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Although the administration of fluid is the first treatment considered in almost all cases of circulatory failure, this therapeutic option poses two essential problems: the increase in cardiac output induced by a bolus of fluid is inconstant, and the deleterious effects of fluid overload are now clearly demonstrated. This is why many tests and indices have been developed to detect preload dependence and predict fluid responsiveness. In this review, we take stock of the data published in the field over the past three years. Regarding the passive leg raising test, we detail the different stroke volume surrogates that have recently been described to measure its effects using minimally invasive and easily accessible methods. We review the limits of the test, especially in patients with intra-abdominal hypertension. Regarding the end-expiratory occlusion test, we also present recent investigations that have sought to measure its effects without an invasive measurement of cardiac output. Although the limits of interpretation of the respiratory variation of pulse pressure and of the diameter of the vena cava during mechanical ventilation are now well known, several recent studies have shown how changes in pulse pressure variation itself during other tests reflect simultaneous changes in cardiac output, allowing these tests to be carried out without its direct measurement. This is particularly the case during the tidal volume challenge, a relatively recent test whose reliability is increasingly well established. The mini-fluid challenge has the advantage of being easy to perform, but it requires direct measurement of cardiac output, like the classic fluid challenge. Initially described with echocardiography, recent studies have investigated other means of judging its effects. We highlight the problem of their precision, which is necessary to evidence small changes in cardiac output. Finally, we point out other tests that have appeared more recently, such as the Trendelenburg manoeuvre, a potentially interesting alternative for patients in the prone position.

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“…To address some of these limitations, a wireless, wearable Doppler ultrasound patch that is easily applied over the common carotid artery has been developed (Fig 1, B and C). 64,[72][73][74][75][76] The device (Flosonics Medical, Sudbury, Ontario, Canada) is cleared by both Health Canada and the US Food and Drug Administration. It uses two continuous-wave, 4-MHz ultrasound beams to transmit and receive; the transducers are housed on a wedge that generates a constant angle of insonation of approximately 60˚.…”

Section: Wearable Doppler Ultrasoundmentioning

confidence: 99%

“…Nevertheless, SV changes induced by squatting, passive leg raising, and simulated end-expiratory inspiratory occlusion maneuvers are captured reliably by the wearable carotid ultrasound patch in healthy subjects. 75 Additionally, novel metrics from the wearable ultrasound, such as the Doppler shock index (DSI, heart rate divided by common carotid VTI), might detect falling SV with greater diagnostic accuracy as compared with traditional vital signs. 74 Although the data accumulated with the ultrasound patch were in healthy volunteers, it agreed with data previously described in various patient populations.…”

Section: Carotid Arterial Dopplermentioning

confidence: 99%

Functional Hemodynamic Monitoring With a Wireless Ultrasound Patch

Kenny

2021

Journal of Cardiothoracic and Vascular Anesthesia

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In this Emerging Technology Review, a novel, wireless, wearable Doppler ultrasound patch is described as a tool for resuscitation. The device is designed, foremost, as a functional hemodynamic monitor-a simple, fast, and consistent method for measuring hemodynamic change with preload variation. More generally, functional hemodynamic monitoring is a paradigm that helps predict stroke volume response to additional intravenous volume. Because Doppler ultrasound of the left ventricular outflow tract noninvasively measures stroke volume in realtime, it increasingly is deployed for this purpose. Nevertheless, Doppler ultrasound in this manner is cumbersome, especially when repeat assessments are needed. Accordingly, peripheral arteries have been studied and various measures from the common carotid artery Doppler signal act as windows to the left ventricle. Yet, handheld Doppler ultrasound of a peripheral artery is susceptible to human measurement error and statistical limitations from inadequate beat sample size. Therefore, a wearable Doppler ultrasound capable of continuous assessment minimizes measurement inconsistencies and smooths inherent physiologic variation by sampling many more cardiac cycles. Reaffirming clinical studies, the ultrasound patch tracks immediate SV change with excellent accuracy in healthy volunteers when cardiac preload is altered by various maneuvers. The wearable ultrasound also follows jugular venous Doppler, which qualitatively trends right atrial pressure. With further clinical research and the application of artificial intelligence, the monitoring modalities with this new technology are manifold.

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A wearable carotid Doppler tracks changes in the descending aorta and stroke volume induced by end‐inspiratory and end‐expiratory occlusion: A pilot study

Cited by 12 publications

References 22 publications

The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate‐to‐severe central hypovolemia during lower body negative pressure

The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate‐to‐severe central hypovolemia during lower body negative pressure

Prediction of fluid responsiveness. What’s new?

Functional Hemodynamic Monitoring With a Wireless Ultrasound Patch

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