COMPARİSON OF THE EFFECTS OF ULTRASOUND-GUİDED ERECTOR SPİNAE PLANE BLOCK AND INTRAMUSCULAR NONSTEROİDAL ANTİ-INFLAMMATORY DRUG ADMİNİSTRATİON ON INTRAOPERATİVE ANALGESİA AND PATİENT SATİSFACTİON DURİNG EXTRACORPOREAL SHOCK WAVE LİTHOTRİPSY

Extracorporeal shock wave lithotripsy (ESWL) is a widely used, non-invasive first-line treatment for urinary stones. Despite advances in lithotripter technology, ESWL still causes discomfort in a large proportion of patients, and analgesia is required in most cases. Pain during ESWL is considered to be cutaneous, somatic and visceral in origin (skin at the coupling site, periosteum, paraspinal muscles and renal capsule) and is mediated by the lower thoracic segments. The erector spinae plane block (ESPB), first described in 2016, delivers local anesthetic into the fascial plane between the transverse process and the erector spinae muscle, from where it spreads to the ventral and dorsal rami of the spinal nerves. It is used for analgesia in thoracic and abdominal surgery and has been reported to relieve renal colic. Its role during ESWL has been examined in only a few studies, and direct comparisons with intramuscular nonsteroidal anti-inflammatory drug (NSAID) regimens, which remain standard practice in many centres, are scarce. The study hypothesis is that ultrasound-guided ESPB provides lower intraoperative pain scores than intramuscular NSAIDs.

Design:

Prospective, randomized, open-label, three-arm, single-centre controlled trial conducted at the Stone Fragmentation Unit of the Urology Clinic, Harran University Hospital, Şanlıurfa, Türkiye. Approved by the Harran University Faculty of Medicine Clinical Research Ethics Committee (decision no. 2022/21/32, 31 October 2022). Written and verbal informed consent is obtained from all participants, and the study is conducted in accordance with the Declaration of Helsinki.

Participants:

Adult patients aged 18-60 years, ASA physical status I-II, scheduled for ESWL for urinary stone disease. Exclusion criteria: refusal to participate, contraindication to intramuscular NSAIDs or to ESPB, inability to cooperate, advanced renal or hepatic insufficiency, and ASA III-V.

Randomization and blinding:

Ninety patients are allocated into three equal groups (n = 30 each) using a computer-free random number table; the allocation is concealed in sealed envelopes opened on the patient's arrival at the unit. Because all blocks are performed by the same anesthesiologist, who also records the intraoperative pain scores, patients and this investigator are not blinded. Postprocedural data (analgesic requirement and satisfaction) are collected by a separate investigator blinded to group allocation.

Interventions:

• Group E (ESPB): With the patient prone and without premedication, a single-injection, unilateral, ultrasound-guided ESPB is performed at the level of the T7 transverse process on the side of the treated kidney. A total of 20 mL of local anesthetic (10 mL 0.5% bupivacaine + 5 mL 2% lidocaine + 5 mL 0.9% saline; final concentrations 0.25% bupivacaine and 0.5% lidocaine; total 50 mg bupivacaine and 100 mg lidocaine) is injected deep to the erector spinae muscle. Patients are observed for 30 minutes before transfer to the procedure room.
• Group N (IM NSAID): 75 mg diclofenac sodium is given intramuscularly 30-45 minutes before ESWL.
• Group K (control): No analgesic premedication, in accordance with the routine practice of the ESWL unit.

There is no intraprocedural rescue analgesia protocol; the session is stopped at the patient's request if pain is not tolerated, and the patient is rescheduled. Analgesics are given on request after the procedure, and this requirement is recorded as an outcome. All patients fast for 6-8 hours and are taught how to use the Visual Analog Scale (VAS) before the procedure.

Outcome assessments:

• Primary outcome: Intraoperative pain intensity on the VAS (0-10), self-reported at the first shock wave (0 min) and at 5, 10, 15, 20, 25 and 30 minutes until the end of the session. For each patient, the mean intraoperative VAS score is calculated by averaging all scores recorded during the procedure.
• Secondary outcomes: Hemodynamic variables (mean arterial pressure, heart rate, SpO2, ECG) monitored throughout and recorded at baseline and at 5, 10, 15, 20, 25 and 30 minutes; postprocedural analgesic requirement at 0, 2, 4, 8, 12 and 24 hours; patient satisfaction on a five-point Likert scale; complications related to the interventions.

Demographic data (age, sex, BMI), smoking status, ASA class, comorbidities and ESWL duration are also recorded.

Sample size:

Calculated with G*Power 3.1 from the VAS difference reported in a previous study of ultrasound-guided fascial plane blocks during ESWL (Yayık et al.). With 80% power and a two-sided alpha of 0.05, at least 27 patients per group are needed; this is increased to 30 per group (90 in total) to allow for dropouts.

Statistical analysis:

Analyses are performed with NCSS 2020. Normality is assessed with the Shapiro-Wilk test and box plots. Three-group comparisons use one-way ANOVA with Bonferroni post hoc testing, or the Kruskal-Wallis test with Dunn-Bonferroni post hoc testing, as appropriate. Within-group changes over time are analysed with repeated-measures analysis. Categorical variables are compared with the chi-square or Fisher-Freeman-Halton tests. The mean intraoperative VAS score is compared among groups with one-way ANOVA (effect size: eta squared), with the Kruskal-Wallis test as a sensitivity analysis. No values are imputed, and all randomized patients are included. Statistical significance is set at p \< 0.05.