Two Bupivacaine Concentrations for Erector Spinae Plane Block in Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy (PNL) is the standard treatment for large and complex renal stones. Despite its minimally invasive nature, postoperative pain remains an important clinical concern and may adversely affect recovery, mobilization, and patient satisfaction. Ultrasound-guided thoracic erector spinae plane block (ESPB) has been increasingly incorporated into multimodal analgesia protocols because of its simplicity, safety profile, and effectiveness in reducing postoperative pain.

The optimal concentration of bupivacaine for ESPB in patients undergoing PNL remains unclear. This study was designed to compare the effects of two different concentrations of bupivacaine (0.25% and 0.375%) administered during ultrasound-guided thoracic ESPB on postoperative pain control and inflammatory response following PNL.

Adult patients scheduled for elective PNL were enrolled. ESPB was performed at the T10 vertebral level under ultrasound guidance before surgery. Participants received 20 mL of either 0.25% or 0.375% bupivacaine. Standard perioperative anesthetic and postoperative analgesic protocols were applied to all participants.

The primary outcome was postoperative pain intensity assessed using Visual Analog Scale (VAS) scores at predefined postoperative time points. Secondary outcomes included intraoperative fentanyl consumption, postoperative tramadol consumption, patient-controlled analgesia requirements, postoperative nausea and vomiting, patient satisfaction, and perioperative changes in inflammatory biomarkers, including the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR).

Demographic characteristics, stone-related variables, operative data, and perioperative hemodynamic parameters were recorded. Statistical analyses were performed to compare postoperative pain outcomes, analgesic requirements, and inflammatory biomarker responses between the study groups.

Inclusion criteria

• Age between 18 and 70 years.
• Scheduled to undergo elective percutaneous nephrolithotomy (PNL).
• American Society of Anesthesiologists (ASA) physical status I-III.
• Received ultrasound-guided thoracic erector spinae plane block (ESPB) before surgery.
• Willing and able to provide written informed consent.

Exclusion criteria

• Inability to assess pain using the Visual Analog Scale (VAS).
• Advanced cardiovascular disease.
• Coagulopathy or bleeding disorders.
• Opioid use disorder.
• Body mass index (BMI) ≥ 40 kg/m².
• Infection at the planned injection site.
• Known allergy or hypersensitivity to bupivacaine, other local anesthetics, or study-related medications.
• Withdrawal of consent during the study period.