This double-blinded randomized controlled trial aims to investigate the effect of intraoperative dexmedetomidine administration on early flap viability and microvascular integrity in cancer patients undergoing elective microvascular reconstructive surgery. The primary outcome is clinical flap viability within 48 hours postoperatively, assessed using a standardized scoring system based on flap color, temperature, capillary refill time, and tissue turgor. Secondary outcomes include the evaluation of biomarkers related to endothelial glycocalyx degradation (syndecan-1), oxidative stress (SOD-1), inflammation (IL-6, IL-10), thrombosis (PAI-1), and angiogenesis (VEGF), as well as microcirculatory assessment using Sidestream Dark Field (SDF) imaging. The study is designed to determine whether dexmedetomidine improves early surgical outcomes by modulating pathophysiological processes involved in microvascular flap success.

Microvascular reconstructive surgery is commonly performed in cancer patients following tumor excision to restore both form and function. However, flap failure remains a major postoperative complication, particularly in oncologic patients who are more susceptible to inflammation, endothelial injury, thrombosis, and impaired tissue perfusion. Recent evidence suggests that anesthetic agents may play a role in modulating microvascular and endothelial responses during surgery, providing opportunities to enhance surgical outcomes.

Dexmedetomidine is a selective alpha-2 adrenergic receptor agonist known for its sedative, analgesic, sympatholytic, and anti-inflammatory properties. In addition to its hemodynamic stability profile, dexmedetomidine has demonstrated protective effects on the endothelium and glycocalyx, along with potential benefits in preserving tissue perfusion and reducing inflammatory and thrombotic responses. However, its clinical impact on microvascular flap outcomes in cancer patients undergoing reconstructive surgery has not been well established.

This study is a double-blinded randomized controlled trial involving 60 adult cancer patients (aged 18 to 65 years) undergoing elective microvascular reconstructive surgery. Participants will be randomized into two groups: an intervention group receiving intravenous dexmedetomidine, and a control group receiving normal saline. Both infusions will be prepared in identical syringes to maintain allocation concealment.

The primary outcome of this study is flap viability within the first 48 hours postoperatively, assessed using a standardized clinical scoring system. This scoring incorporates four key parameters: flap color, surface temperature, capillary refill time, and tissue turgor. Each parameter is evaluated to provide an integrated assessment of early microvascular flap function.

The secondary outcomes include exploratory analysis of biological processes related to microvascular integrity and function. These outcomes include the evaluation of biomarkers indicative of endothelial glycocalyx degradation (syndecan-1), oxidative stress (SOD-1), inflammatory activity (IL-6 and IL-10), prothrombotic state (PAI-1), and angiogenesis (VEGF). These markers will be analyzed from plasma and/or flap tissue at defined perioperative time points to better understand the physiological impact of dexmedetomidine.

Furthermore, real-time assessment of tissue microcirculation will be performed using Sidestream Dark Field (SDF) imaging, a non-invasive technique that enables visualization of capillary density and flow quality in the reconstructed flap area. This provides an objective and dynamic measure of tissue-level perfusion and complements the clinical viability scoring.

All patients will undergo general anesthesia induced with fentanyl 2 µg/kg and propofol 1-2 mg/kg. In the intervention group, dexmedetomidine will be administered with a loading dose of 1 µg/kg over 10 minutes, followed by a continuous infusion at 0.4 µg/kg/hour until 48 hours after surgery. The control group will receive a matched volume of normal saline according to the same timeline.

This study is expected to provide new insights into the role of dexmedetomidine in enhancing microvascular outcomes in cancer patients undergoing reconstructive surgery, potentially offering a simple yet impactful strategy to improve flap success and postoperative recovery.

Inclusion Criteria:

1. Adult patients (aged 18-65 years) diagnosed with cancer who are scheduled to undergo microsurgical flap reconstruction.
2. Patients within the age range of 18 to 65 years at the time of enrollment.
3. Patients who provide written informed consent to participate in the study.

Exclusion Criteria:

1. Patients with a history of uncontrolled diabetes mellitus.
2. Patients diagnosed with chronic kidney disease.
3. Patients with known liver failure.
4. Patients receiving corticosteroid therapy prior to surgery.
5. Patients with uncontrolled hypertension.
6. Patients with a history of chemotherapy or radiotherapy prior to surgery.
7. Patients diagnosed with preoperative sepsis.
8. Patients requiring perioperative vasopressor support.
9. Patients with a history of prior surgery in the same operative field.
10. Patients who decline to participate in the study.

Individual participant data (IPD) will not be shared due to concerns regarding patient confidentiality and the limited scope of data use as outlined in the informed consent. The collected data will be used solely for the purposes of this specific clinical study and will not be made publicly available.

This trial employs a double-blind masking design in which both participants and clinical staff, including surgeons and outcome assessors, are blinded to the treatment allocation. The dexmedetomidine and placebo infusions will be prepared and administered by an independent pharmacist or designated unblinded personnel not involved in patient care or data collection, ensuring unbiased assessment of outcomes.