Evaluation of Corrected Carotid Artery Flow Time as a Predictor of Fluid Responsiveness in Spontaneous Breathing Patients

Study Overview
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Brief Summary
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It is still challenging to assess intravascular volume status in spontaneously breathing patients. Recently, the measurement of corrected flow time in carotid artery was introduced as quite useful, simple and noninvasive for the evaluation of circulating blood volume change. The aim of this study is to evaluate whether corrected carotid artery flow time as determined by ultrasonography can be a predictor of fluid responsiveness in spontaneously breathing patients before induction of general anesthesia.

Conditions
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Brain Tumor

Intervention / Treatment
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* Device: ultrasonographic measurement of corrected flow time in carotid artery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: adult patients (19-80 years of age) who were scheduled to undergo elective neurosurgery for brain tumor Exclusion Criteria: BMI > 35 or < 15 kg/m2 the presence of carotid artery stenosis > 50% systolic blood pressure > 160 mmHg cardiac rhythm other than sinus intracardiac shunt 6. valvular heart disease a left ventricular ejection fraction of < 50% right ventricular dysfunction 9 chronic obstructive pulmonary disease pulmonary hypertension chronic kidney disease (eGFR < 60 mL/min/1.73m2) pregnancy

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 80 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 |
| --- | --- |
| Fluid loading group<br>Spontaneously breathing patients before induction of general anesthesia who receive fluid loading | Device: ultrasonographic measurement of corrected flow time in carotid artery<br>* Corrected carotid artery flow time is measured using 10-5 MHz linear probe on a portable ultrasound machine. On the two-dimensional image, the optimal image of the long-axis view is obtained at the left common carotid artery. The sample volume is placed on the center of the lumen, 2 cm proximal to the bulb, and a pulsed wave Doppler examination was performed while the Doppler beams were adjusted to ensure < 60° of angle for the best signal. Then, cardiac cycle time and carotid flow time is measured. Carotid flow time is measured between the upstroke of the flow tracing and the dicrotic notch, and it is corrected for pulse rate by dividing flow time by the square root of the cardiac cycle time to calculate corrected carotid artery flow time (flow time/√cycle time).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ultrasonographic measurement of corrected flow time in carotid artery | The ultrasonographic measurement of corrected flow time in carotid artery will be performed before fluid loading. | right before fluid loading | 
| ultrasonographic measurement of corrected flow time in carotid artery | The ultrasonographic measurement of corrected flow time in carotid artery will be performed 5 minutes after fluid loading. | 5 minutes after fluid loading |