Volume Responsiveness By Ultrasound Of Carotid Blood Flow In Patients With Cardiogenic Shock

Study Overview
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Brief Summary
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Resuscitation of critically ill patients has changed since the advent of goal directed therapy. Today, practitioners providing fluid resuscitation are attentive of the danger associated with volume depletion while being aware of the morbidity of volume overload. Fluid resuscitation must be rapid, precise, and individually tailored to each patient based on reliable data obtained by various means inside ICU setting. There is no non-invasive method that can reliably and accurately identify fluid responsiveness. As such, in patients with undifferentiated shock, treatment often involves empiric fluid administration, in the hopes that volume expansion will increase preload, which will then serve to increase cardiac output (CO). However, for patients on the flat portion of the Starling curve, aggressive fluid administration results in no appreciable increase in CO and may be detrimental to hemodynamically unstable patients.

Detailed Description
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Study location and population: Alexandria Main University Hospitals ICU, Alexandria Egypt. Approval of the Medical Ethics Committee of Alexandria Faculty of Medicine was obtained before the start of the study. Sample size was estimated using PASS version 20 program. The minimal hypothesized total sample size of 40 cardiogenic shock patients of both sexes is needed to determine the sensitivity and specificity of cardiac output measurement using either bedside ultrasound on carotid artery and TTE (Standard) while assessing volume responsiveness with 95 % confidence level and 80 % power using z-test. Study procedures: All enrolled patients were subjected on admission to thorough history taking including age, sex, date of ICU admission and preexisting underlying disease (Diabetes Mellitus, hypertension), presence of sepsis, smoking, analgesic abuse. Full clinical examination. Severity of illness was assessed by Acute Physiological And Chronic Health Evaluation-ΙΙ (APACHE ΙΙ). ICU length of stay (LOS) and final outcome were recorded. Noninvasive measurement of Systolic arterial pressure, diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), and temperature were recorded upon admission and after PLR. Fluid challenge: A PLR was performed, Transferring a patient to the passive leg raising (PLR) position (in which the lower limbs are elevated at 45_ while the trunk is lying supine) transfers venous blood from the legs to the intrathoracic compartment and increases cardiac preload around 300-500 mL. Carotid ultrasonography and Echocardiogram: Stroke volume is the amount of blood ejected from the ventricle with each cardiac cycle. It can be readily calculated by subtracting the end-systolic volume from the end-diastolic volume. Multiplying the stroke volume by the heart rate yields the cardiac output, typically reported in liters per minute. Stroke volume can be estimated by using a combination of 2D and Doppler imaging. HR was recorded before and after PLR test then CO is calculated by equation of: CO = π × (LVOTd)2/4 × VTI LVOT × HR Percent change is [(cardiac output after passive leg raising - cardiac output before passive leg raising)/cardiac output after passive leg raising] × 100%. A greater than 10% increase in cardiac output would predict volume responsiveness and constitute an indication for a 500-mL fluid bolus. Measurements were repeated as needed, and fluid resuscitation continued until no further response to passive leg raising was noted. Changes (%) =100 X (post-FC value - baseline value)/ baseline value Patients were divided into 2 groups: Responder is defined by an increase of 10% or more. Non responder is less than 10%. The Common Carotid artery is a large superficial accessible artery so carotid doppler flow imaging would be simple, non-invasive method to assess volume responsiveness. Use of Velocity Time Integral of flow through the Common Carotid artery (Carotid VTI) and Passive Leg Raising (PLR) described as a marker of volume responsiveness in hemodynamically unstable patients. Carotid flow is measured during the passive leg raising maneuver by using a linear array transducer positioned in the long axis over the CCA, after procuring a longitudinal view of the common carotid artery, pulsed Doppler analysis at 2 cm from the bifurcation was performed. The CCA diameter is measured from opposing points of the vessel's intimal wall, with the velocity time integral determined automatically using spectral Doppler envelopes and the sample obtained from the center of the artery. Common carotid artery blood flow per minute is calculated by the equation CBF= π × (CCA diameter)2/4 × CCA velocity time integral × heart rate This parameter is measured both before and after the passive leg raising to determine the percent change in CCA blood flow. An increase in CCA flow with passive leg raising only occurs in patients with shock, and an increase of greater than 20% is highly predictive of volume responsiveness. HR is recorded before and after PLR then CBF was calculated by the following equation: CBF = π × (CCA diameter)2/4 × VTI CCA × HR Patients was divided into 2 groups: Responder is defined by an increase of 20% or more. Non responder is less than 20%. After fluid challenge we remeasured Systolic arterial pressure, diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR) to assess clinical response to the fluid challenge.

Official Title
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Assessment Of Volume Responsiveness By Ultrasound Parameters Of Carotid Blood Flow In Patients With Cardiogenic Shock

Conditions
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Cardiogenic Shock, Volume Responsiveness, Ultrasound

Intervention / Treatment
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* Other: Transthoracic echocardiography and Carotid artery doppler (PHILIPS HD11 XE ultrasound device) before and after PLR test.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 18 Y. Cardiogenic shock. Exclusion Criteria: Age < 18 Y. Pregnant females. All types of shock state other than cardiogenic. Peripheral arterial disease. Non consenting patients. Unable to tolerate passive leg raise (PLR). Common carotid artery stenosis greater than 50 % (systolic peak velocity >182 cm/s and/or diastolic velocity >30 cm/s by Doppler ultrasound.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cardiogenic Shock Patients<br>Cardiac output and Carotid Blood flow is measured before & after PLR test, then percent change is calculated were increase in cardiac output with 10 % or more is considered volume responder. Measurements can be repeated as needed, and fluid resuscitation continues until no further response to passive leg raising is noted. | Other: Transthoracic echocardiography and Carotid artery doppler (PHILIPS HD11 XE ultrasound device) before and after PLR test.<br>* VTI-LVOT was measured by echo by placing the pulsed wave Doppler sample gate in the LVOT diameter in apical-5-chamber window. VTI-LVOT was obtained by manually tracing the Doppler velocity spectrum. LVOT velocity time integral was recorded before and after PLR test within 2 minutes. Carotid blood flow was measured by using two-dimensional image, the optimal image of the long-axis view was obtained at the common carotid artery. The sample volume was placed on the center of the lumen, 2 cm proximal to the bulb, and a pulsed wave Doppler examination,The angle correction cursor was placed parallel to the direction of blood flow. A PLR will be performed in 2 sequential steps, first step patient is seated in the semi recumbent position (45°) then using an automatic bed elevation technique, the lower limbs will be then raised to a 45° angle while the patient's trunk will be lowered in supine position. Thus, the angle between the trunk and the lower limbs will remain unchanged (135°).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percent Change in Carotid Blood Flow after PLR test. | The common carotid artery will be scanned in transverse and longitudinal planes. Spectral Doppler tracings will be then obtained by placing a 0.5 mm sample gate through the center of vessel, within 2-3 cm proximal to the carotid bulb in the longitudinal plane, in accordance to standard guidelines. The angle correction cursor will be placed parallel to the direction of blood flow. A PLR will be performed in 2 sequential steps, first step patient is seated in the semi recumbent position (45°) then using an automatic bed elevation technique, the lower limbs will be then raised to a 45° angle while the patient's trunk will be lowered in supine position. Thus, the angle between the trunk and the lower limbs will remain unchanged (135°). Percent change is [(cardiac output after passive leg raising - carotid blood flow before passive leg raising)/carotid blood flow after passive leg raising] × 100%. A greater than 20% increase in carotid blood flow would predict volume responsiveness. | Change in carotid blood flow within 2 minutes after PLR. | 
| Percent Change in Cardiac Output after PLR test. | Cardiac output is measured using pulsed Doppler imaging where phase-array transducer positioned just proximal to the aortic valve. The velocity time integral is measured by tracing the modal velocity then stroke volume is calculated.CO is SV multiplied by HR. A PLR will be performed in 2 sequential steps, first step patient is seated in the semi recumbent position (45°) then using an automatic bed elevation technique, the lower limbs will be then raised to a 45° angle while the patient's trunk will be lowered in supine position. Thus, the angle between the trunk and the lower limbs will remain unchanged (135°). Percent change is [(cardiac output after passive leg raising - cardiac output before passive leg raising)/cardiac output after passive leg raising] × 100%. A greater than 10% increase in cardiac output would predict volume responsiveness. | Change in cardiac output within 2 minutes after PLR. | 
| Blood Pressure before and after PLR test. | Measure Blood Pressure and record reading in mmHg before and after PLR test. | Change in blood pressure 1 minute after PLR. | 
| Heart rate before and after PLR test. | Record Heart Rate readings on monitor in BPM (beat per minute) before and after PLR test. | Change in heart rate 1 minute after PLR. |