Comparison of Paravertebral Versus Epidural Block for Post-thoracotomy Pain Control

This is a randomized, assessor-blinded, non-inferiority clinical trial conducted at Hospital de Clínicas de Porto Alegre, Brazil, in adult patients undergoing elective open thoracotomy with one-lung ventilation. The objective is to compare the analgesic efficacy of continuous thoracic paravertebral block (BPV) versus continuous thoracic epidural block (BPD) for postoperative pain control during the first 48 hours after surgery.

Patients will be randomly allocated to two groups (40 per group). In the BPV group, the paravertebral catheter is inserted at the end of surgery under direct thoracoscopic vision (without ultrasound), using a bolus of ropivacaine 0.375% (15 mL fractionated) followed by continuous infusion of bupivacaine 0.125% at 0.10 mL/kg/h. In the BPD group, the epidural catheter is inserted at the beginning of surgery using the loss-of-resistance technique with the same bolus and infusion regimen. The target dermatomal level is T5-T7 (or T5-T9).

The primary outcome is the mean pain score at rest measured by the Numeric Verbal Scale (NVS 0-10) at 6, 12, 24, and 48 hours postoperatively. Secondary outcomes include pain on movement, total opioid consumption (converted to morphine equivalents), block-related complications (hypotension, urinary retention, technical failure, motor block), clinically significant pulmonary and cardiovascular complications, length of hospital stay, and patient satisfaction with analgesia.

Randomization is centralized using variable block sizes and sealed numbered envelopes. Outcome assessors are blinded to allocation. Both groups receive identical multimodal analgesia and a standardized rescue protocol. The sample size of 80 participants was calculated to demonstrate non-inferiority with a margin of 1 point on the NVS (expected SD = 1.5; 80% power; one-sided α = 0.025).

The study was approved by the Research Ethics Committee of HCPA (Opinion No. 8.544.882; CAAE 98467026.8.0000.5327) and will be conducted in accordance with the Declaration of Helsinki and current Brazilian regulations.

Inclusion criteria

• Patients aged 18 years or older;
• Elective thoracic surgeries requiring open thoracotomy;
• American Society of Anesthesiologists (ASA) physical status I to III.

Exclusion criteria

• Pregnancy or lactation;
• Urgent or emergency surgeries;
• Contraindications to epidural catheter insertion or neuraxial anesthesia;
• Infection at the proposed block site;
• Patient refusal to undergo the study blocks;
• Video-assisted thoracic surgeries;
• Anticipated need for invasive mechanical ventilation in the postoperative period;
• Chronic opioid use (daily use for more than 3 months of ≥10 mg oral morphine equivalent);
• Severe vertebral deformities or previous thoracic spine surgery that prevent safe performance of the blocks;
• Known allergy to local anesthetics, opioids, or study medications;
• Body mass index > 35 kg/m²;
• Advanced liver or kidney failure (Child-Pugh C or estimated glomerular filtration rate < 50 mL/min/1.73 m²);
• Severe cognitive impairment that prevents understanding of instructions or pain assessment.