The Effect of Use of Tranexamic Acid in Percutaneous Nephrolithotomy on Blood Loss and Surgical Visual Clarity

The study was designed as a double-blind, prospective, randomised, controlled study after approval of our Institutional ethics committee (dossier no: 108-2021) and assessed patients scheduled for PCNL after January 2022 for eligibility. After obtaining written informed consent, 75 patients (3 groups; 1:1:1 distribution; n=25) were allocated, and the study was conducted in Haseki Training and Research Hospital until May 2023, with the principles outlined in the Helsinki Declaration.

Study subjects The study population was 18-70 years old and ASA I-III patients scheduled for PCNL surgery. Exclusion criteria were tranexamic acid hypersensitivity, history of subarachnoid haemorrhage, previous cerebrovascular event, a history of arterial-venous embolism or a tendency to thromboembolism, abnormal liver function tests, unstable cardiovascular disease, acute or chronic renal failure, presence of any haematological disease and known colour blindness.

Patient randomization and blindness Randomization was designed as 3 (n= 25) named Groups A, B, and Group C in a 1:1:1 ratio with a computer-based algorithm and sealed in opaque envelopes by the surgeon assigned to the study. The investigative anesthesiologist selected an envelope in the order of numbers on it, and Group A continued with an IV infusion of 10 mg/kg tranexamic acid for 20 minutes just before the surgical incision. In Group B, 10 mg/kg tranexamic acid was placed in the first irrigation solution; in Group C, no drug was given either way. The urologist was blind to the study groups and was the evaluator of an intraoperative visual score. Postoperative Hb and Hct values and complications were followed by the surgeons who were also blinded to the groups, and the decision of blood replacement was made according to the Hct values according to our standard protocol of the urology department.

Anaesthesia and surgical technique All surgeries were performed under general anaesthesia with standard monitorisation and non-invasive MASIMO Hemoglobin (SpHb®) real-time monitoring. After the ureteral catheter was placed, the patient was placed in a prone position. After sequential dilatations were performed under fluoroscopy, a 16.5 Fr or 21 Fr am Platz sheath was placed in the pelvicalyceal system. Ho: YAG Laser lithotripter (Sphinx, Lisa laser, USA) was used to fragment stones. According to the surgeon's decision, a JJ stent and/or a nephrostomy tube were placed at the final of the operation.

Primary outcome The primary outcome was the comparison of changes in haemoglobin and haematocrit values during two postoperative days with changes in intraoperative SpHb values and postoperative need for blood transfusion. SpHb was monitored throughout the surgery; however, the value of change before and immediately after surgery was a major concern. Blood samples were evaluated for Hb and Hct values on the first night and the second morning after surgery. Indications for blood transfusion were below 30% hematocrit level.