Microcirculatory DiffusionVeMicNCT07052461
Association of Microcirculation, Vexus Score and Femoral Vein Doppler in Patients on the ICU After Non-emergency Cardiac Surgery
An observational study of Microcirculatory Diffusion and Microcirculatory Convection Capacity, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
Trial summary
The aim of the VeMic study is to explore if venous congestion is linked with microcirculatory impairment in elective cardiac surgery patients in the postoperative ICU stay. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Microcirculatory Diffusion, Microcirculatory Convection Capacity, Venous Congestion
- How many people
- 40 participants
- Where
- 1 siteSwitzerland
- Study dates
- 14 Apr 2026to 30 Sep 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Adult, Older adult
Study population: Patients presenting for elective or urgent cardiac surgery. Urgent patients are defined as patients who have not been electively admitted for operation but who require intervention or surgery on the current admission for medical reasons. These patients cannot be sent home without a definitive procedure but do not require immediate emergency surgery.
Who may be able to join
- Age ≥ 18 years
- Elective or urgent (need for definitive procedure during hospitalisation, but not emergency intervention) cardiac surgery
Who cannot join
- Age < 18 years
- Pregnant women
- Known severe chronic kidney disease (estimated glomerular filtration rate <15 mL/min per 1.73 m2 or dialysis)
- Renal or liver transplantation
- Any known condition interfering with Doppler evaluation of the portal system (including known or suspected cirrhosis or portal vein thrombosis or huge abdominal emphysema).
- Inability to consent to study
- Emergency cardiac surgery
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site, 1 recruiting
- Recruiting
University Hospital Basel
Basel, 4031
Gregor Loosen, MD, +41 61 328 40 90, gregormichael.loosen@usb.ch
Alexa Hollinger, MD
About this study
The aim of the VeMic study is to explore if venous congestion is linked with microcirculatory impairment in elective cardiac surgery patients in the postoperative ICU stay.
Read the detailed description
Cardiac surgery is associated with a significant risk of postoperative complications, including organ dysfunction such as acute kidney injury (AKI). Traditionally, clinical management in the intensive care unit (ICU) has focused on monitoring macrocirculatory parameters-such as blood pressure, cardiac output, and central venous pressure (CVP)-to guide treatment. However, adequate systemic perfusion does not always translate into sufficient tissue oxygenation at the microcirculatory level. Microcirculation, which occurs in the smallest vessels such as capillaries, is where oxygen and nutrients are actually delivered to the cells. Impairment in microcirculatory function can occur even when macrocirculatory values appear normal, leading to what is known as loss of hemodynamic coherence. Despite growing evidence of the clinical importance of microcirculation, routine bedside assessment remains limited due to technical challenges and the lack of easily applicable tools.
While elevated CVP and signs of venous congestion have been linked to worse outcomes such as AKI, the underlying mechanisms remain poorly understood. CVP alone is an imperfect marker for venous stasis and does not reliably predict microcirculatory impairment. Newer ultrasound-based tools-such as the Vexus score and femoral vein Doppler (FVD)-are emerging as promising, non-invasive methods to assess venous congestion at the bedside. However, it is currently unclear whether these sonographic signs of venous congestion are actually associated with impaired microcirculatory function. This knowledge gap limits clinicians' ability to interpret ultrasound findings in the context of microvascular health and to make informed decisions about fluid management and organ perfusion.
The VeMic study aims to investigate whether ultrasound-based indicators of venous congestion correlate with objectively measured microcirculatory impairment in patients admitted to the ICU after non-emergency cardiac surgery. By combining ultrasound assessments with advanced analysis of sublingual microcirculation using handheld vital microscopy and automated software, the study seeks to bridge the gap between macro- and microcirculatory monitoring. The findings may help determine whether these easily accessible ultrasound tools can be used to detect early signs of microvascular dysfunction and guide more targeted, physiology-based interventions in the postoperative setting.
- Conditions
- Microcirculatory Diffusion, Microcirculatory Convection Capacity, Venous Congestion, Postoperative Cardiac Surgery, Fluid Management, Haemodynamic Coherence
- Keywords
- vexus score, femoral vein doppler, intensive care unit
- Medical subject headings
- Hyperemia
What is being measured
The primary outcome is the main question the study is designed to answer.
Difference in red blood cell velocity: concested vs non-congested
Difference in red blood cell velocity (RBCv) between patients grouped as congested (Vexus score of 2 and 3) vs. non-congested (Vexus score of 0 and 1).
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in total vessel density: concested vs non-congested
Difference in total vessel density (TVD) between patients grouped as congested (Vexus score of 2 and 3) vs. non-congested (Vexus score of 0 and 1).
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in red blood cell velocity: physiologic femoral vein flow vs. pulsatile pattern
Difference in red blood cell velocity (RBCv) between patients with a physiologic femoral vein flow vs. pulsatile pattern
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in total vessel density between patients with a physiologic femoral vein flow vs. pulsatile pattern
Difference in total vessel density (TVD) between patients with a physiologic femoral vein flow vs. pulsatile pattern
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Secondary outcomes (4)
Difference in RBCv between patients with different Vexus scores
Difference in RBCv between patients with a Vexus score of 0 vs. 1 vs. 2 vs. 3
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference inTVD between patients with different Vexus scores
Difference inTVD between patients with a Vexus score of 0 vs. 1 vs. 2 vs. 3
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in microcirculatory reserve capacity: congested non-congested
Difference in microcirculatory reserve capacity between patients grouped as congested (Vexus score of 2 and 3) vs. non-congested (Vexus score of 0 and 1)
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in microcirculatory reserve capacity: physiologic femoral vein flow vs. pulsatile patern
Difference in microcirculatory reserve capacity between patients with a physiologic femoral vein flow vs. pulsatile patern
Measured: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Jul 2025
- Study start14 Apr 2026
- Primary completionJun 2027 (estimated)
- Study completion30 Sep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Microcirculatory DiffusionStudies of the same condition, open and under way.
- More trials run by University Hospital, Basel, SwitzerlandThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital, Basel, Switzerland
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Martin Siegemund, Prof. MD, Study chair, University Hospital of Basel
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07052461
- Sponsor's protocol ID
- 2025-00579; am24Siegemund
- Other IDs
- 2025
- Acronym
- VeMic
- Status last verified
- Aug 2026
- First submitted
- 26 Jun 2025
- Last updated
- 25 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 25 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Association of Microcirculation, Vexus Score and Femoral Vein Doppler in Patients on the ICU After Non-emergency Cardiac Surgery
- ClinicalTrials.gov ID
- NCT07052461
- Acronym / sponsor ID
- VeMic / 2025-00579; am24Siegemund
- Conditions
- Microcirculatory Diffusion, Microcirculatory Convection Capacity, Venous Congestion, Postoperative Cardiac Surgery, Fluid Management, Haemodynamic Coherence
- Keywords
- vexus score, femoral vein doppler, intensive care unit
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- University Hospital, Basel, SwitzerlandUniversity, hospital or other
- Study start
- 14 Apr 2026 (actual)
- Primary completion
- Jun 2027 (estimated)
- Study completion
- 30 Sep 2027 (estimated)
- First posted
- 4 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The aim of the VeMic study is to explore if venous congestion is linked with microcirculatory impairment in elective cardiac surgery patients in the postoperative ICU stay.
Detailed description
Cardiac surgery is associated with a significant risk of postoperative complications, including organ dysfunction such as acute kidney injury (AKI). Traditionally, clinical management in the intensive care unit (ICU) has focused on monitoring macrocirculatory parameters-such as blood pressure, cardiac output, and central venous pressure (CVP)-to guide treatment. However, adequate systemic perfusion does not always translate into sufficient tissue oxygenation at the microcirculatory level. Microcirculation, which occurs in the smallest vessels such as capillaries, is where oxygen and nutrients are actually delivered to the cells. Impairment in microcirculatory function can occur even when macrocirculatory values appear normal, leading to what is known as loss of hemodynamic coherence. Despite growing evidence of the clinical importance of microcirculation, routine bedside assessment remains limited due to technical challenges and the lack of easily applicable tools.
While elevated CVP and signs of venous congestion have been linked to worse outcomes such as AKI, the underlying mechanisms remain poorly understood. CVP alone is an imperfect marker for venous stasis and does not reliably predict microcirculatory impairment. Newer ultrasound-based tools-such as the Vexus score and femoral vein Doppler (FVD)-are emerging as promising, non-invasive methods to assess venous congestion at the bedside. However, it is currently unclear whether these sonographic signs of venous congestion are actually associated with impaired microcirculatory function. This knowledge gap limits clinicians' ability to interpret ultrasound findings in the context of microvascular health and to make informed decisions about fluid management and organ perfusion.
The VeMic study aims to investigate whether ultrasound-based indicators of venous congestion correlate with objectively measured microcirculatory impairment in patients admitted to the ICU after non-emergency cardiac surgery. By combining ultrasound assessments with advanced analysis of sublingual microcirculation using handheld vital microscopy and automated software, the study seeks to bridge the gap between macro- and microcirculatory monitoring. The findings may help determine whether these easily accessible ultrasound tools can be used to detect early signs of microvascular dysfunction and guide more targeted, physiology-based interventions in the postoperative setting.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Age groups
- Adult, Older adult
- Study population
- Patients presenting for elective or urgent cardiac surgery. Urgent patients are defined as patients who have not been electively admitted for operation but who require intervention or surgery on the current admission for medical reasons. These patients cannot be sent home without a definitive procedure but do not require immediate emergency surgery.
Key inclusion criteria (2 listed)
- Age ≥ 18 years
- Elective or urgent (need for definitive procedure during hospitalisation, but not emergency intervention) cardiac surgery
Key exclusion criteria (7 listed)
- Age < 18 years
- Pregnant women
- Known severe chronic kidney disease (estimated glomerular filtration rate <15 mL/min per 1.73 m2 or dialysis)
- Renal or liver transplantation
- Any known condition interfering with Doppler evaluation of the portal system (including known or suspected cirrhosis or portal vein thrombosis or huge abdominal emphysema).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Difference in red blood cell velocity: concested vs non-congested
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in red blood cell velocity (RBCv) between patients grouped as congested (Vexus score of 2 and 3) vs. non-congested (Vexus score of 0 and 1).
Difference in total vessel density: concested vs non-congested
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in total vessel density (TVD) between patients grouped as congested (Vexus score of 2 and 3) vs. non-congested (Vexus score of 0 and 1).
Difference in red blood cell velocity: physiologic femoral vein flow vs. pulsatile pattern
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in red blood cell velocity (RBCv) between patients with a physiologic femoral vein flow vs. pulsatile pattern
Difference in total vessel density between patients with a physiologic femoral vein flow vs. pulsatile pattern
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in total vessel density (TVD) between patients with a physiologic femoral vein flow vs. pulsatile pattern
4 secondary outcomes
Difference in RBCv between patients with different Vexus scores
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference inTVD between patients with different Vexus scores
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in microcirculatory reserve capacity: congested non-congested
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Difference in microcirculatory reserve capacity: physiologic femoral vein flow vs. pulsatile patern
Time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Aug 2026.
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Martin Siegemund, Prof. MD study chair
University Hospital of Basel
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Microcirculatory Diffusion and Microcirculatory Convection Capacity, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 25 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Gregor Loosen,, MD (+41 61 328 40 90, gregormichael.loosen@usb.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Difference in red blood cell velocity: concested vs non-congested (time frame: 3 measurements:T0 prior surgery, T1 first post-operative day, T2 6 hours after T1). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Aug 2026.