Comparison of IV Analgesia Protocols After the Regional Block's Effect Diminishes in Thoracic Surgery

Thoracic surgery is associated with one of the highest incidences of both acute and chronic postoperative pain. Clinical evidence indicates that poorly controlled acute pain in the immediate postoperative period is a primary risk factor for the development of chronic neuropathic pain (post-thoracotomy pain syndrome). Furthermore, severe acute pain triggers a guarding reflex, leading to shallow breathing, impaired coughing, and ultimately compression atelectasis.

In alignment with the 2026 American Society of Anesthesiologists (ASA) guidelines, this study emphasizes a multimodal, opioid-sparing approach to optimize patient recovery. While regional techniques like the Erector Spinae Plane (ESP) block offer effective early analgesia, their effectiveness is typically limited to 8-12 hours. This study evaluates the effectiveness of three different IV Patient-Controlled Analgesia (PCA) regimens initiated specifically to bridge the analgesic gap after the regional block's effect diminishes.

Interventions:

All patients receive a standardized ultrasound-guided ESP block (20 ml 0.25% bupivacaine) at the end of surgery. PCA regimens (Fentanyl, Tramadol, or Ibuprofen) are initiated at the 6th postoperative hour (or earlier on patient demand). Postoperative static and dynamic pain scores (VAS), rescue analgesic requirements and respiratory performance (incentive spirometry volumes) are monitored for 72 hours.

The study hypothesizes that the Ibuprofen-based PCA will maintain comparable analgesia to opioid-based regimens while significantly improving respiratory performance by avoiding opioid-induced respiratory depression.

Study Design and Blinding:

This is a prospective, randomized, single-center trial. Patients are assigned to one of three intervention arms using a centralized randomization system with the sealed envelope method (1:1:1 ratio). The study follows a double-blind (participant and outcomes assessor) protocol. While the primary investigator manages the PCA devices, the patients and the researchers recording the visual analog scale (VAS) scores and incentive spirometry volumes are blinded to the group assignments.

Inclusion criteria

• - Patients aged 18 to 80 years.
• - ASA (American Society of Anesthesiologists) Physical Status Score of I-III.
• - Body Mass Index (BMI) between 18 and 35 kg/m².
• - Undergoing elective thoracic surgery via Video-Assisted Thoracoscopic Surgery (VATS).
• - Voluntary participation confirmed by signing the written Informed Consent Form.

Exclusion criteria

• - Age below 18 or above 80 years.
• - Advanced organ failure (e.g., severe hepatic or renal impairment).
• - ASA physical status > III.
• - History of chronic pain treatment or long-term opioid use.
• - BMI < 18 kg/m² or > 35 kg/m².
• - Pregnancy or breastfeeding.
• - Limited cooperation due to dementia or uncontrolled psychiatric disorders.
• - Communication barriers (inability to communicate in the native language).
• - History of substance or drug abuse.
• - Known allergy or contraindication to the study drugs (Fentanyl, Tramadol, or Ibuprofen).
• - Contraindication to regional block placement (e.g., infection at the injection site).