Carotid Artery Corrected Flow Time Measured by Ultrasonography as a Predictor of Hypotension After Induction of General Anesthesia

Study Overview
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Brief Summary
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Hypotension often happens immediately after anesthetic induction. Particularly in 5-10 minutes after anesthetic induction it is reported to happen more frequently. Patients may have preexisting hypovolemia resulting from dehydration and impaired compensatory responses, which increase the risk. However, it is still challenging to assess intravascular volume status in spontaneously breathing patients before anesthetic induction. 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. The aim of this study is to evaluate whether corrected carotid artery flow time as determined by ultrasonography in spontaneously breathing patients before general anesthesia can predict hypotension after induction.

Official Title
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Carotid Artery Corrected Flow Time Measured by Ultrasonography as a Predictor of Hypotension After Induction of General Anesthesia

Conditions
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General Anesthesia Induction for Elective Surgery

Intervention / Treatment
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* Procedure: ultrasonographic measurement of corrected flow time(FTc) 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 surgery under general anesthesia Exclusion Criteria: mean blood pressure < 70 mmHg before induction of general anesthesia Patients who have currently taken angiotensin-converting enzyme inhibitor Patients who have currently taken angiotensin receptor blocker the presence of carotid artery stenosis > 50% cardiac rhythm other than sinus unstable angina a left ventricular ejection fraction of < 40% severe vascular disease implanted pacemaker/cardioverter autonomic nervous system disorders anticipated difficult airway 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 |
| --- | --- |
| Hypotension after anesthetic induction group<br>Patients with hypotension after anesthetic induction | Procedure: ultrasonographic measurement of corrected flow time(FTc) 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. 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). The blood pressure was taken before anesthetic induction and every two minutes after anesthetic induction till ten minutes after endotracheal intubation.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| corrected flow time (FTc) in carotid artery | the area under the receiver operating characteristics curve of corrected flow time in carotid artery measured by ultrasonography to predict hypotension after anesthetic induction | 10 minutes before induction of general anesthesia. |