Study design and participants
chronic pain, infections, cardiovascular or respiratory diseases
CHRONIC PAIN, INFECTIONS, BLEEDING DISORDERS, PROXIMAL URETERAL STONE
In this randomized clinical trial conducted between April 2021 and June 2021, patients with proximal ureteral stones less than 15 mm who were candidates for transurethral lithotripsy (TUL) at Razi Educational Hospital in Rasht were prospectively enrolled. Patients aged between 15 and 65 years, of both genders, with ASA Class I/II, were included. Patients were excluded if they had a recent history of opioid analgesic use just before surgery, bleeding disorders, chronic pain conditions, cardiovascular or respiratory diseases, infections at the site of block injection, pregnancy, or a known allergy to bupivacaine and fentanyl. Additionally, individuals requiring supplementary anesthesia due to an unsatisfactory block or those with absolute or partial prohibitions for intrathecal injection were not included. Considering an error protection of 0.05, a power of 0.8, an effect size of 83%, and assuming a dropout rate of 10%, the sample size required per group was 27 to achieve the desired statistical significance for the alternative hypothesis, i.e., adequate spinal anesthesia when adding fentanyl.