A dynamic elastance-based protocol to guide intra-operative fluid management in major abdominal surgery

BACKGROUND: Arterial hypotension during major surgery is related to postoperative complications and mortality. Both fluids and vasopressors increase blood pressure (BP) by inducing different physiological response. We devised a protocol which relies on dynamic arterial elastance (Ea dyn ) to guide BP optimisation during major abdominal surgery, and tested its effectiveness on tissue perfusion. OBJECTIVE: To explore if an Ea dyn -based optimisation protocol could affect lactate levels, fluid administration, and postoperative clinical complications. DESIGN: Randomised open-label clinical trial. SETTING: High-volume tertiary care centre for pancreatic surgery. PATIENTS: From 58 patients scheduled for cephalic duodenopancreatectomy 46 were eligible for the study. MAIN OUTCOMES AND MEASURES: The primary endpoint was the lactate value one hour after extubation. Secondary endpoints were fluid balance, intra-operative hypotension and postoperative complications. In the control group, hypotension (mean arterial pressure < 65 mmHg) was treated based on stroke volume variation (SVV) while in the experimental group the treatment was based on assessment of dynamic arterial elastance (Ea dyn group). Patient demographic and pre-operative laboratory data were recorded. All haemodynamic data, including oxygen delivery and consumption, were recorded at four time points: after intubation (T0), after fascia opening (T1), after fascia closing (T2) and one hour after extubation (T3). RESULTS: The patients were 70 [63 to 76] years and 15 (33%) were ASA 3. Lactate levels at T3 were similar between the control and Ea dyn groups. Oxygen consumption was higher in the Ea dyn group at T3, and lactate had a significant percentage decrease from T2 to T3: median [IQR], -24.5 [-30 to -14] vs. 0 [-24 to 7.6]%, P = 0.004). Those in Ea dyn group received more vasopressors and had a lower fluid balance at T3: 2700 [2100 to 3800] vs. 2200 [1060 to 3000] ml, P = 0.020). There were no significant differences either in postoperative complications or hospital stay. CONCLUSIONS: A protocol including Ea dyn to treat hypotension did not reduce lactate after major abdominal surgery, but it was associated with a significant reduction in fluid balance and increase in oxygen consumption. TRIAL REGISTRATION: ClinicalTrials.gov NCT05187273.