A Study Comparing Carotid Doppler Ultrasound and Echocardiography to Assess Fluid Responsiveness in Septic Patients on Ventilator

June 16, 2026 updated by: Sana Zulfiqar, Pakistan Institute of Medical Sciences

Comparative Evaluation of Common Carotid Artery Blood Flow (CCABF) and Transthoracic Echocardiographic Cardiac Output (TTE-CO) for Assessing Fluid Responsiveness in Septic Patients on Ventilator.

The goal of this clinical trial is to determine whether common carotid artery blood flow measured by bedside Doppler ultrasound can accurately identify fluid responsiveness in mechanically ventilated adults with sepsis. The study will compare this method with transthoracic echocardiography-derived cardiac output, which is a commonly used non-invasive technique for assessing hemodynamic status in critically ill patients. The study also aims to evaluate whether carotid artery ultrasound can provide a faster and more practical bedside assessment during fluid resuscitation in the intensive care unit.

In patients with sepsis, giving too little intravenous fluid may worsen organ perfusion and shock, while excessive fluid administration may lead to complications such as pulmonary edema, worsening oxygenation, prolonged mechanical ventilation, and longer intensive care unit stay. Because of this, clinicians need reliable methods to identify which patients are likely to benefit from fluid administration. This concept is known as fluid responsiveness.

The main questions this study aims to answer are:

  • Can common carotid artery blood flow measured by ultrasound predict fluid responsiveness as accurately as transthoracic echocardiography-derived cardiac output?
  • How closely do changes in carotid artery blood flow correspond to changes in cardiac output during passive leg raising?
  • Can carotid ultrasound provide a quicker and simpler bedside method for assessing fluid responsiveness in critically ill patients receiving mechanical ventilation? Researchers will compare two ultrasound-based methods during a passive leg raising test. Passive leg raising is a temporary bedside maneuver used to simulate a fluid challenge without immediately giving intravenous fluids. During this maneuver, the patient's legs are elevated while the upper body is lowered, allowing blood from the lower limbs to temporarily return to the central circulation. This increases blood flow to the heart and may increase cardiac output in patients who are likely to respond to fluid administration.

The study team will first record baseline measurements of common carotid artery blood flow and transthoracic echocardiographic cardiac output while the patient is in a semi-recumbent position. The passive leg raising maneuver will then be performed, and both measurements will be repeated to evaluate changes in blood flow and cardiac output. If the predefined criteria for fluid responsiveness are met, the participant will receive intravenous crystalloid fluid according to the study protocol.

Participants will:

  • Undergo bedside Doppler ultrasound measurement of common carotid artery blood flow
  • Undergo transthoracic echocardiography to measure cardiac output
  • Have ultrasound measurements recorded before and after passive leg raising
  • Receive intravenous fluid administration if fluid responsiveness criteria are met
  • Continue routine monitoring of blood pressure, heart rate, oxygenation, urine output, and other intensive care parameters during the study period The findings from this study may help determine whether carotid artery ultrasound can be used as a practical bedside tool for fluid assessment in mechanically ventilated patients with sepsis, particularly in settings where rapid and non-invasive monitoring is needed.

Study Overview

Status

Status

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Recruiting

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Detailed Description

This study is being conducted in the intensive care unit to examine a non-invasive ultrasound-based approach for evaluating circulatory response in adults with sepsis who are receiving mechanical ventilation. The investigation focuses on whether Doppler assessment of blood flow in the common carotid artery can provide clinically useful information comparable to cardiac output measurements obtained through transthoracic echocardiography during bedside hemodynamic assessment.

Management of septic patients frequently requires decisions regarding intravenous fluid administration. Both insufficient and excessive fluid therapy may negatively affect patient outcomes. Reliable bedside techniques that identify patients who are likely to benefit from additional fluid remain an important component of critical care practice. Current hemodynamic assessment methods often require specialized expertise, repeated examinations, or technically challenging image acquisition in ventilated patients.

This trial will assess circulatory changes produced by a passive leg raising maneuver. Passive leg raising temporarily increases venous return by transferring blood from the lower limbs toward the thoracic circulation. The maneuver provides a reversible physiologic preload challenge that allows evaluation of cardiovascular response without initially administering intravenous fluid.

Participants enrolled in the study will undergo sequential ultrasound-based hemodynamic assessments performed by trained investigators. Measurements will first be obtained while the participant is positioned with the head elevated. The participant will then undergo passive leg raising with elevation of both lower limbs and adjustment of trunk position according to study protocol. Repeat hemodynamic measurements will be recorded during the maneuver.

For carotid Doppler evaluation, the common carotid artery will be visualized in longitudinal orientation using a high-frequency linear ultrasound probe. Vessel diameter and Doppler flow measurements will be obtained from a standardized location proximal to the carotid bulb. Flow estimation will be derived from Doppler velocity measurements combined with arterial diameter and heart rate.

Cardiac output assessment will be performed separately using transthoracic echocardiography and Doppler evaluation of flow across the left ventricular outflow tract. Measurements will be obtained using standardized echocardiographic views and procedural methods.

Participants who demonstrate predefined hemodynamic changes during assessment may receive crystalloid administration according to the study protocol. Additional measurements may then be performed to evaluate circulatory response after fluid administration.

The primary analysis will evaluate the diagnostic performance of carotid Doppler-derived flow assessment for identifying preload responsiveness in comparison with transthoracic echocardiographic measurements. Agreement between both methods and the ability of carotid Doppler assessment to identify clinically significant hemodynamic change will also be examined.

Additional analyses will assess bedside practicality, including the ease and duration of ultrasound assessment in critically ill ventilated patients. Technical factors affecting image acquisition and measurement reliability will also be documented during the study.

Clinical information and ultrasound findings will be entered into standardized study forms. Data review procedures will include consistency checks, verification of recorded values, and evaluation of incomplete or missing variables before statistical analysis. Statistical methods will include correlation analysis, agreement testing, and calculation of diagnostic performance measures using predefined study thresholds.

This investigation may provide further evidence regarding the role of carotid Doppler ultrasound as a rapid bedside technique for circulatory assessment in mechanically ventilated adults with sepsis managed in the intensive care unit.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
94

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

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Study Contact

Study Contact

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Study Contact Backup

Study Locations

  • Pakistan
    • Federal Area
      • Islamabad, Federal Area, Pakistan, 44000
        • Recruiting
        • Pakistan Institute Of Medical Sciences
        • Contact:

Participation Criteria

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Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • • Adults with sepsis requiring mechanical ventilation in the intensive care unit

    • Patients requiring fluid assessment or fluid resuscitation based on clinical findings, including one or more of the following:

      • Heart rate greater than 100 beats per minute
      • Systolic blood pressure less than 90 mmHg
      • Mean arterial pressure less than 65 mmHg
      • Urine output less than 0.5 mL/kg/hour for at least 2 hours

Exclusion Criteria:

  • Intracranial pathology associated with raised intracranial pressure, including intracerebral hemorrhage or space-occupying lesions
  • Recent neurosurgical procedures or conditions where passive leg raising may increase intracranial pressure
  • Known heart failure
  • Significant cardiac arrhythmias
  • Significant valvular heart disease
  • Status asthmaticus
  • Pulmonary hypertension
  • Pulmonary embolism
  • Pregnancy
  • Lower limb conditions preventing passive leg raising, including fractures
  • Intra-abdominal hypertension
  • Recent abdominal surgery
  • Known carotid artery disease or common carotid artery stenosis greater than 50%

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Mechanically ventilated septic patients undergoing fluid responsiveness assessment
Participants enrolled in this study arm will undergo non-invasive bedside hemodynamic evaluation during passive leg raising. Doppler ultrasound of the common carotid artery and transthoracic echocardiographic assessment of cardiac output will be performed at predefined stages of assessment to examine circulatory changes associated with preload variation. Intravenous crystalloid administration may be provided when study-defined indicators of preload responsiveness are observed, followed by reassessment using the same ultrasound-based methods.
Drug: intravenous crystalloid fluid bolus
Intravenous isotonic crystalloid solution will be administered to participants who demonstrate predefined indicators of fluid responsiveness during hemodynamic assessment. A 500 mL fluid bolus will be infused according to intensive care unit protocol following passive leg raising-associated circulatory changes identified by ultrasound-based monitoring methods. Hemodynamic reassessment will be performed after fluid administration to evaluate changes in circulatory parameters.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Diagnostic Accuracy of Common Carotid Artery Blood Flow- Cardiac Output in predicting fluid responsiveness.
Time Frame: Peri-Procedural
This outcome will evaluate the ability of Doppler-derived common carotid artery blood flow measurements to identify fluid responsiveness in mechanically ventilated adults with sepsis using transthoracic echocardiography-derived cardiac output as the reference method. Diagnostic performance will be assessed through sensitivity, specificity, predictive values, overall accuracy, and agreement analysis during passive leg raising assessment.
Peri-Procedural

Collaborators and Investigators

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Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Pakistan Institute of Medical Sciences

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Chair: Rana Imran SIkander, MBBS, MCPS, FCPS, Pakista Institute of Medical Sciences
  • Study Director: Syed Muneeb Ali, MBBS, MCCM, MD CCM, Pakistan Institute Of Medical Sciences

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 29, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 4, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 17, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 18, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 20-4/AS&RB-M/SZAMU/2025-2378

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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