Corrected Flow Time in the Carotid Artery as a Predictor of Fluid Responsiveness in Mechanically Ventilated Patients With Low Tidal Volume in the Intensive Care Unit

Study Overview
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Brief Summary
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The purpose of this study is to evaluate predictability of carotid corrected flow time for fluid responsiveness in mechanically ventilated patients with low tidal volume in the intensive care unit.

Official Title
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Corrected Flow Time in the Carotid Artery as a Predictor of Fluid Responsiveness in Mechanically Ventilated Patients With Low Tidal Volume in the Intensive Care Unit

Conditions
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Hypovolemic

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 with age more than 19 Undergoing postoperative mechanical ventilation with low tidal volume Clinically diagnosed with hypovolemic status If one of follow criteria is satisfied 1) Systolic blood pressure <90mmHg 2) Mean arterial pressure(MBP)<70mmHg or fall more than 20% from baseline 3) Heart rate >100bpm 4) Urine output <0.5mg/kg/hr more than 1 hour 5) Arterial lactate >2mmol/L 6) Capillary refilling time >3secs Exclusion Criteria: Body mass index <40 or >15 kg/m2 Medical history of carotid artery stenosis >50% or diagnosed while examination Cardiac arrhythmia other than normal sinus rhythm Moderate or severe valvular heart disease, intracardiac shunt, heart failure, pulmonary hypertension Moderate or severe chronic obstructive pulmonary disease Increased intracranial pressure Using vasopressor Pregnancy

Ages Eligible for Study
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Minimum Age: 19 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>Mechanically ventilated patients with low tidal volume in the intensive care unit whom clinician decided to provide fluid for correction of hypovolemia | Device: Ultrasonographic measurement of corrected flow time in carotid artery<br>* Corrected carotid artery flow time is measured using 6-13 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 |
| --- | --- | --- |
| Corrected carotid artery flow time during low tidal volume ventilation | Area under the receiver operating curve of Corrected carotid artery flow time for fluid responsiveness in low tidal volume ventilator setting before fluid resuscitation | Procedure (During low tidal volume ventilation before fluid resuscitation) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pulse pressure variation during low tidal volume ventilation | Area under the receiver operating curve of pulse pressure variation for fluid responsiveness in low tidal volume ventilator setting before fluid resuscitation | Procedure (During low tidal volume ventilation before fluid resuscitation) |