A Study of Pain Reduction After Pulmonary Resection by RATS-TT, RATS-OTC, and Hybrid RATS.

Chronic Pain After Thoracic Surgery: Towards a New Standard? A Comparative Prospective Study of Pain Reduction After Pulmonary Resection by RATS-TT, RATS-OTC, and Hybrid RATS.

Pulmonary resections are key in treating lung neoplasms, with techniques adapted to tumor size and location. Minimally invasive approaches like VATS have replaced open thoracotomy, but intercostal trocar placement can lead to nerve injury and chronic pain.

Robotic-assisted thoracic surgery (RATS) is usually done via a transthoracic (RATS-TT) approach using intercostal trocars. A newer "out of cage" method (RATS-OTC), using subcostal or subxiphoid ports, avoids intercostal access, potentially reducing nerve damage. A French study showed less opioid use and acute pain with RATS-OTC, but chronic pain outcomes are still unknown.

At CHUM, a hybrid RATS technique (RATS-TTH) is also used-intercostal for instruments, but with out-of-cage specimen extraction-to limit intercostal trauma.

Pulmonary resections play a crucial role in the treatment of lung neoplasms, with procedures tailored to the size and location of the tumors. The minimally invasive approach, particularly via video-assisted thoracoscopic surgery (VATS), has replaced traditional thoracotomy by allowing access to the thoracic cavity through surgical trocars inserted between the ribs. However, these trocars, placed near the intercostal nerves, can cause nerve injury and chronic pain.

Robotic-assisted thoracic surgery (RATS) is typically performed via a transthoracic approach (RATS-TT), using intercostal trocars similar to those in VATS. Recently, a robotic approach known as "out of cage" (RATS-OTC) has been described, which involves the use of subcostal or subxiphoid trocar insertion. This method avoids the passage of instruments through the intercostal space, thus theoretically eliminating the risk of intercostal nerve injury. Compared to the transthoracic approach, a French team reported a reduction in opioid use and decreased intensity of acute postoperative pain with the RATS-OTC approach. However, due to the novelty of this technique, chronic pain outcomes have yet to be compared with those observed in RATS-TT or VATS.

At the CHUM, a modified transthoracic RATS technique-called the hybrid approach (RATS-TTH)-is also used. In this method, trocars are placed intercostally, but the extraction of large pulmonary specimens is performed through an out-of-cage route to minimize potential intercostal trauma related to specimen removal. Pain associated with this approach has also not been described in the literature.

Postoperative pain significantly affects recovery and long-term quality of life. Although the VATS approach reduces the severity of acute pain, chronic pain remains common and impactful. In fact, in the CRYO-VATS study conducted at CHUM between 2023 and 2025, the incidence of chronic pain following pulmonary resection via VATS (without cryoanalgesia) was 30% at 3 months and 17.5% at 6 months.

The aim of this study is to describe the incidence of chronic pain at 3 and 6 months for the three surgical approaches used at CHUM:

RATS-OTC (robotic, completely spares the intercostal space),

RATS-TT (robotic, intercostal passage of instruments and pulmonary specimen),

RATS-TTH (robotic, hybrid technique with intercostal instrument passage but out-of-cage extraction of the pulmonary specimen).

The investigators hypothesize that the RATS-OTC approach will reduce the incidence of chronic pain by completely eliminating intercostal trauma. Currently, no study has reported on chronic pain outcomes comparing the RATS-TTH and RATS-OTC approaches. Simultaneous data collection from patients undergoing RATS-TT will serve as a comparison baseline. These preliminary data will provide the foundation for a randomized controlled trial to validate the potential chronic pain benefits of these innovative surgical approaches.

Inclusion Criteria:

• Patients aged 18 years and older
• American Society of Anesthesiologists (ASA) score 1-3

Exclusion Criteria:

• Language barrier, psychiatric, physical or mental condition making pain assessment impossible despite prior education
• Patient refusal to participate
• Patients reoperated by VATS or thoracotomy in the postoperative period in the context of the occurrence of complications