In situ exploration of endothelial function in vasoplegic syndrome after cardiac surgery with cardiopulmonary bypass: protocol for a single-centre prospective cohort study - the Vasoshock study.
This paper describes a protocol for a prospective cohort study (the Vasoshock study) designed to compare endothelial function via allometrically corrected brachial artery flow-mediated dilation between patients with and without vasoplegic syndrome 48 hours after cardiac surgery with cardiopulmonary bypass.
Key Findings
Methods
Vasoplegic syndrome after cardiac surgery with cardiopulmonary bypass is defined operationally in this protocol as requiring norepinephrine bitartrate ≥0.05 µg/kg/min for at least 4 hours to maintain mean arterial pressure ≥65 mm Hg after CPB weaning.
The definition requires haemodynamic optimisation and exclusion of a predominant low-cardiac-output phenotype or another cause of shock before classifying a patient as having VS.
VS is characterised clinically by vasodilation, hypotension and vasopressor dependence.
The protocol distinguishes VS from other shock phenotypes, including low cardiac output states.
Methods
The study will enrol 124 adults aged 18-80 years undergoing cardiac surgery with cardiopulmonary bypass, comprising 62 patients with vasoplegic syndrome and 62 patients without vasoplegic syndrome.
This is a prospective, single-centre observational cohort study conducted at a single centre.
Participants must be adults aged 18-80 years.
The two groups (VS and non-VS) are planned to be of equal size at 62 participants each.
The study is registered under ClinicalTrials.gov identifier NCT06318689.
Methods
The primary outcome is allometrically corrected brachial artery flow-mediated dilation (FMD) compared between VS and non-VS patients at 48 hours after cardiopulmonary bypass weaning.
The primary statistical comparison will use multiple linear regression for corrected FMD at 48 hours with prespecified covariate adjustment.
FMD measurements will also be performed at 4-8 hours after CPB weaning in addition to the 48-hour primary timepoint.
Allometric correction of FMD is specified, reflecting methodology intended to account for baseline arterial diameter effects.
Methods
The study combines flow-mediated dilation, sublingual side-stream dark-field imaging, and biomarkers to assess postoperative vascular phenotyping across two timepoints.
Sublingual side-stream dark-field (SDF) imaging will be used to assess microcirculation.
Both FMD and SDF imaging will be assessed at 4-8 hours and at 48 hours after CPB weaning.
Secondary and exploratory analyses will assess SDF-derived parameters, biomarkers, and associations across modalities.
The rationale for combining modalities is that endothelial dysfunction, dysregulated nitric oxide signalling, inflammation, and glycocalyx injury may each contribute to vasoplegic syndrome.
Methods
The study received ethical approval from the Comité de Protection des Personnes Sud-Méditerranée III and follows French law requirements for non-interventional routine-care studies.
French law for this non-interventional routine-care study requires prior oral and written information and absence of opposition rather than written informed consent.
Absence of opposition will be documented for each participant.
Results are planned to be published in peer-reviewed journals and presented at scientific conferences.
Background
Endothelial dysfunction, dysregulated nitric oxide signalling, inflammation, and glycocalyx injury are identified as potential contributors to vasoplegic syndrome after cardiac surgery with cardiopulmonary bypass.
The abstract highlights these mechanisms as the biological rationale for studying endothelial function in this population.
The study aims to improve understanding of postoperative vascular phenotyping by examining these pathways.
No quantitative data on these mechanisms are reported, as this is a study protocol paper.
What This Means
This paper describes the design and protocol for a clinical study called the Vasoshock study, which has not yet reported results. The study is investigating a serious complication called vasoplegic syndrome (VS) that can occur after heart surgery using a heart-lung bypass machine. Vasoplegic syndrome causes the blood vessels to relax too much, leading to dangerously low blood pressure that requires medications to keep it under control. Researchers suspect that damage to the inner lining of blood vessels (the endothelium) plays a key role, and this study is designed to test that hypothesis.
The study plans to enrol 124 adult patients undergoing cardiac surgery — 62 who develop vasoplegic syndrome and 62 who do not — and compare how well their blood vessels function at two timepoints after surgery: 4-8 hours and 48 hours after coming off the bypass machine. The main measurement will be a non-invasive ultrasound test called flow-mediated dilation, which measures how well blood vessels can widen in response to increased blood flow. The researchers will also look at the tiny blood vessels under the tongue using a special camera and measure various blood markers related to blood vessel health.
This research suggests that understanding the blood vessel abnormalities underlying vasoplegic syndrome could lead to better ways to identify which patients are affected and potentially guide treatment decisions. By combining multiple ways of measuring blood vessel function at the same time, the study aims to build a more complete picture of what goes wrong in the vascular system after heart surgery with bypass. The protocol itself has been ethically approved, and the study findings, once collected, will be shared through scientific publications and conferences.
Ferry N, Renard D, Gillibert A, Clavier T, Tamion F, Abedi A, et al.. (2026). In situ exploration of endothelial function in vasoplegic syndrome after cardiac surgery with cardiopulmonary bypass: protocol for a single-centre prospective cohort study - the Vasoshock study.. BMJ open. https://doi.org/10.1136/bmjopen-2026-122692