Comparison of the effects of liberal and restrictive fluid management on the endothelial glycocalyx layer during the perioperative period in major urological surgeries

Objective: To compare the effects of liberal and restrictive fluid therapies applied during the intraoperative period on ANP release and endothelial glycocalyx layer in major urological surgeries. Our primary hypothesis in this study is that ANP and the endothelial damage markers (heparan sulfate, hyaluronan and syndecan 1) will be significantly higher in the group which we applied liberal fluid therapy. Materials and Methods: The study is completed with 39 ASA II-III patients, over the age of 18 who underwent radical cystectomy ileal loop/orthotopic bladder operation, following the approval of the ethics committee and patient consents. The patients were randomized by the closed envelope method and divided into two groups, liberal and restrictive fluid therapy. ECG, pulse oximetry, invasive artery monitoring and central venous cannulation were performed in all patients. Arterial cannulas were integrated into the hemodynamic monitoring system with a special transducer and advanced cardiac hemodynamic values were recorded throughout the operation. In the Restrictive group, 2ml/kg/hour Ringer's lactate infusion and 2 mcg/kg/hour norepinephrine infusion were initiated. In case of hypotension, the norepinephrine dose was increased up to 8mcg/kg/hour. 250 ml Ringer's lactate bolus was administered to patients whose mean arterial pressure was below 65 mmHg although the norepinephrine dose was 8 mcg/kg/hour. In the Liberal group, fluid resuscitation was intiated with Ringer's lactate at a dose of 10ml/kg/hour. 250 ml Ringer's lactate bolus was administered to patients whose mean arterial pressure was below 65 mmHg. If hypotension persists, 250 ml fluid boluses were repeated up to 10 times. Blood samples were taken twice, preoperatively and postoperatively to evaluate the levels of ANP and glycocalyx degredation products, heparan sulfate, hyaluronan and syndecan 1. Results: There was no significant difference between the two groups in terms of demographic and intraoperative hemodynamic parameters of the patients (p>0.05). The amount of crystalloid and colloid replaced in the intraoperative period and the urine output on the 1st and 2nd day postoperatively were significantly higher in the Liberal group, compared to the Restrictive group (p<0.0001, p=0.013, p=0.002, p<0.0001). The number of patients using vasopressor was found significantly higher in the Restrictive group, compared to the Liberal group (p<0.0001). In the Liberal group, postoperative ANP, hyaluronan and syndecan 1 levels were found significantly higher than in the preoperative period (p=0.004, p=0.034). Postoperative ANP, hyaluronan and syndecan 1 levels were significantly higher in the Liberal group compared to the Restrictive group (p=0.003, p=0.047, p=0.048). Conclusions: Measurement of serum ANP, hyaluronan and syndecan 1 levels can be used as an indirect measurement method to show endothelial glycocalyx damage and intraoperative hypervolemia in major urological surgeries. Liberal fluid therapy may cause damage to the endothelial glycocalyx layer by increasing ANP in patients undergoing major urological surgery. Restrictive fluid therapy applied with preemptive norepinephrine infusion in major surgeries does not cause any visible impairment in the macrocirculation and preserves the microcirculation without disturbing the integrity of the vessel endothelium.