The purpose of this observational study is to examine whether Endotheliopathy of Trauma (EoT) is present in severely burned patients and how it is affected by burn debridement surgery.

The main questions it aims to answer are:

• Do severely burned patients present with EoT before undergoing burn debridement surgery?
• Does the surgical intervention worsen EoT, leading to increased postoperative syndecan 1 (sdc 1) levels compared to preoperative levels?

Participants will:

• Undergo debridement surgery where the total area of debrided and donor sites covers 20% or more of the Total Body Surface Area (TBSA).
• Have their sdc 1 levels measured before and after surgery.
• Have perioperative factors analyzed to assess their impact on endothelial damage and glycocalyx functionality.

This study aims to provide insight into how surgical resuscitation affects the endothelial glycocalyx in severely burned patients.

The endothelial glycocalyx is a protective layer of glycoproteins, glycosaminoglycans, and proteoglycans that lines the luminal surface of blood vessels and plays a critical role in regulating vascular permeability and coagulation. The syndecan family, consisting of four members (syndecan 1-4), is the main proteoglycan. Of particular interest, sdc 1 is a marker of endothelial damage, with elevated levels (>40 ng/ml) being linked to EoT. This condition is characterized by increased transfusion requirements, prolonged hospital stays, and higher morbidity and mortality rates.

Early burn debridement (from the fifth day onward) has been associated with improved outcomes in severely burned patients. The purpose of this surgical intervention is to mitigate the inflammatory response triggered by the burned (and potentially infected) skin. However, this surgery presents significant challenges for anesthesiologists, as it typically involves massive blood loss and may exacerbate the shock that these patients frequently experience. To counteract hemorrhagic shock induced by the surgical trauma, fluid and blood product administration is critical. The state of the endothelial glycocalyx may influence the effectiveness of surgical resuscitation. When damaged, the glycocalyx heightens the risk of postoperative pulmonary edema, prolonged mechanical ventilation, abdominal or limb compartment syndrome, and deepened burns due to poor perfusion. These complications increase the likelihood of sepsis, multi-organ failure, and elevated mortality.

This study aims to evaluate whether EoT is present in severely burned patients before surgery and assess whether the surgical intervention exacerbates this condition. Investigators will conduct a two-year prospective observational cohort study at the Burn Unit of Vall d'Hebron University Hospital, from March 2024 to March 2026. The study will include patients undergoing burn debridement surgery involving 20% or more of their TBSA. Plasma sdc 1 levels will be measured preoperatively and postoperatively to assess glycocalyx disruption. Additionally, investigators will analyze perioperative factors to determine their relationship with endothelial damage.

The literature on severely burned patients and the endothelial glycocalyx is limited, with no studies to date specifically addressing its role in surgical resuscitation. Quantifying perioperative sdc 1 levels will help provide a clearer understanding of the status and function of the glycocalyx in these patients. This insight could contribute to strategies aimed at protecting the endothelial glycocalyx, potentially reducing postoperative complications related to fluid therapy and positively impacting the morbidity and mortality of severely burned patients.

Inclusion Criteria:

• Patients over 18 years old with burned TBSA greater than or equal to 20%.
• Patients who will undergo debridement of at least 20% of the burned TBSA (including the debrided area and the donor site).

Exclusion Criteria:

• Under 18 years old.
• Pregnant women.
• Patient refusal.
• Polytraumatized patients.
• Electrical or chemical burns.
• Patients with any of the following pre-burn conditions: complicated heart disease*, renal disease on hemodialysis/hemofiltration or with Glomerular Filtration Rate (GFR) < 30 ml/min/1.73m², and liver cirrhosis (Child A, B, and C).

(* Definition of complicated heart disease: decompensated heart failure (NYHA class IV), Left Ventricular Ejection Fractio < 40%, or severe valvular disease).

• Patients with a history of chronic inflammatory diseases (autoimmune disease).
• Patients on chronic treatment with corticosteroids or immunosuppressants.
• Patients requiring reintervention for debridement surgery who have already been included in the study during their first surgery.

Patients admitted to the Burn Unit of Vall d'Hebron University Hospital with burned TBSA ≥ 20% who undergo debridement surgery (total area between the debrided and donor sites ≥ 20% of TBSA).

De-identified individual participant data that will be shared include:

• Demographic data (e.g., age, sex, weight, height,)
• Clinical data (e.g., medical history, burn characteristics, TBSA, type of burn)
• Outcome measures (e.g., syndecan-1 levels, postoperative complications, survival rates)

The IPD and supporting information will be available starting 6 months after the final study results are published and will remain available for 5 years.

Qualified researchers affiliated with academic, medical, or scientific institutions will be able to access the IPD and supporting information. They will be able to access de-identified individual participant data, including demographic information, clinical data, and outcome measures. Researchers can request access to the data by submitting a data-sharing proposal to Vall d'Hebron University Hospital and signing a data use agreement. Requests will be evaluated on a case-by-case basis.