The volume kinetics of the commercially available colloid fluid, Gelofusine 4%, have not been previously studied. Adult patients undergoing open vascular surgery, including femoral and carotid endarterectomy as well as bypass surgery, received general anesthesia. Following the induction of anesthesia, Gelofusine 4% was administered at a dosage of 10 ml/kg over a 30-minute period. Hemoglobin concentration was monitored for up to 180 minutes post-administration to construct a plasma hemodilution profile.

Gelofusine 4% was administered at a dosage of 10 ml/kg over a 30-minute period to adult patients undergoing uncomplicated vascular surgery. Arterial blood samples were taken to measure blood hemoglobin concentration and hematocrit at baseline and at 5-minute intervals up to 60 minutes after the infusion began, followed by 10-minute intervals up to 90 minutes, and then at 30-minute intervals up to 180 minutes. Urine output and total intraoperative blood loss were continuously monitored. The plasma hemodilution data were fitted to a bicompartmental model to derive the intercompartmental kinetics of Gelofusine 4%.

Inclusion Criteria:

• Informed consent.
• Elective open vascular surgery with a minimal risk of perioperative complications.
• Hemodynamic stability before induction (no chest pain, SBP > 100 mmHg, MAP ≥ 60 mmHg, 50 < HR < 100 bpm).

Exclusion Criteria:

• Known allergy to 4% Gelofusine.
• Patient refusal to participate in the study.
• Non-elective/emergency surgical interventions.
• The American Society of Anesthesiologists (ASA) > 3.
• Any preoperative hemodynamic support (mechanical or pharmacological).
• Moderate or severe left ventricular dysfunction (LVEF ≤ 44%).
• Moderate or severe right ventricular dysfunction.
• Diastolic dysfunction of any degree.
• Baseline hypoxemia index < 300 mmHg.

Adult patients aged 18 to 80 years undergoing uncomplicated vascular surgery under general anesthesia.