In Situ Exploration of Vascular Function in Vasoplegic Shock Following Cardiac Surgery With Cardiopulmonary Bypass

The goal of this observational study is to assess in situ vascular function, glycocalyx and microcirculation in postoperative vasoplegic shock following cardiac surgery with cardiopulmonary bypass.

The main question is to investigate the relationship between NO-dependent vasomotor reserve and the presence of vasoplegic shock following cardiac surgery with cardiopulmonary bypass.

Participants will have two visits, during which a number of non-invasive examinations will be carried out to study glycocalyx, microcirculation and vascular function. Biological and morphological data will be collected up to 3 months after inclusion, as well as information on treatments administered and outcome.

Researchers will compare a group of patients with vasoplegic shock against a group without vasoplegic shock in order to study possible alterations in function in the vasoplegic shock group.

Objective : the primary objective of this study is to explore in situ the glycocalyx, the microcirculation and vascular function in postoperative vasoplegic shock following cardiac surgery with CPB. Secondary objectives are to study links between vascular function and damage to the glycocalyx and microcirculation and patient prognosis, in particular their impact on fluid balance.

Method :

Constitution of a single-centre prospective cohort study of 124 patients. Patients hospitalised in the cardiac intensive care unit after cardiac surgery with CPB will be consecutively included from 4 to 24 hours after surgery: 62 patients with vasoplegic shock (noradrenaline \> 0.05µg/kg/min for at least 4 hours and after correction of any hypovolaemia), 62 patients without vasoplegic shock.

Endothelial function will be assessed using the flow-mediated dilation (FMD) method to test brachial artery vasodilation mediated by nitric oxide (NO) after induced ischemia. Microcirculation and glycocalyx will be evaluated using GlycoCheck, providing several measurements of microcirculation and glycocalyx using Sidestream Dark Field technology (mucosal illumination by a green LED and continuous x20 magnification video recording at the sublingual mucosa level). Various endothelial and inflammatory markers will also be measured (VCAM-1, syndecan, endothelin, interleukin-6).

Each patient will be assessed at inclusion and 48 hours using GlycoCheck, FMD, and endothelial measurements, then followed through their medical records for 90 days, where a follow-up call will be conducted to assess outcomes. Collected information will include routine care data (morphological data, vital signs, laboratory tests, fluid balance, scores, treatments, surgical data).

Both groups will be compared using statistical tests, and risk factors for developing vasoplegic shock will be explored through logistic regression. Univariable analysis followed by multivariable logistic regression with backward data inclusion will then be performed to identify risk factors for vasoplegic syndrome within the entire cohort (necessarily including FMD and GlycoCheck). A p-value \<0.05 will be considered statistically significant.

Eligibility Criteria:
Inclusion Criteria:

* Patients aged between 18 and 80 years old
* Patient undergoing cardiac surgery with cardiopulmonary bypass
* Hospitalised in a cardiac surgical unit, between 4 and 24 hours after the end of cardiopulmonary bypass, after volemic optimisation

Exclusion Criteria:

* Sepsis at inclusion
* Cardiac transplant
* Circulatory assistance
* Known alteration of the microcirculation
* Any condition contraindicating measurement via Glycocheck or flux mediated dilatation measurement
* New surgery within 48 hours of the operation
* Person deprived of liberty by an administrative or judicial decision or person placed under legal protection / sub-guardianship or guardianship
* Patient refusal