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.