Continuous Thoracic Paravertebral Analgesia for Video-assisted Thoracoscopic Surgery

Postoperative Pain

This study is designed to assess: * The impact of continuous thoracic paravertebral nerve blockade compared to intercostal nerve blockade on the intensity of postoperative pain following VATS in subjects having a Patient Controlled Analgesia (PCA) device as their primary analgesic modality. * The impact of continuous thoracic paravertebral analgesia on length of stay, opioid intake, respiratory function, incidence of side-effects and postoperative complications. The basic hypothesis of this study is that continuous thoracic paravertebral nerve blockade will provide superior postoperative analgesia following VATS when compared to intercostal nerve blockade in patients having a PCA device as their primary analgesic modality. Superior quality of analgesia should contribute to preserve pulmonary function, reduce opioid intake and related side-effects and shorten the hospital stay.

Appropriate postoperative analgesia is crucial in fast-track surgery, which is a multimodal therapeutic strategy that aims toward enhanced postoperative recovery and shortened hospital stay. Although VATS is considered a minimally invasive procedure, patients have reported moderate to severe pain of variable duration following surgery. The ideal postoperative analgesia regimen for VATS has not been elucidated. Systemic opioids given through patient-controlled devices (PCA) are routinely used after these procedures but their analgesic effect can be limited and undesirable side-effects may occur. Intercostal nerve blockade is also widely used to alleviate pain following VATS and can be used as an adjunct to systemic opioids. Paravertebral nerve blockade is an interesting alternative for analgesia following VATS. The duration of pain relief associated with paravertebral nerve blockade may vary from 4 to 48 hours. However, the duration of the analgesic effect can be prolonged using a continuous infusion of local anesthetics. This study will compare the efficacy of continuous ambulatory paravertebral analgesia to intercostal analgesia. All patients will have a PCA device as their primary analgesic modality. Methods: Seventy patients will be randomized to receive either continuous paravertebral analgesia or intercostal analgesia. Anesthetic technique and monitoring will be standardized. On arrival in the recovery room, each patient will have a PCA device installed. PCA doses will be standardized. All patients will also receive acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDS) as co-analgesia. PCA will be removed 24 hours after surgery and oral opioids will then be administered as needed. From their arrival in the recovery room, patients in the paravertebral analgesia group will be administered a bupivacaine 0.0625% infusion through a conventional infusion pump at a rate of 10 mL/h. Before discharge from the hospital on the day following surgery or at the latest on the morning of the second day, the bupivacaine infusion will be transferred to a portable elastomeric pump. The infusion will continue for the next 30 hours at a rate of 10 mL/h. During the first 72 hours following surgery, the following information will be recorded: intensity of pain, opioid intake, side-effects attributable to analgesia and patient's level of satisfaction towards pain management. The occurence of pulmonary complications will be noted. Lung function will be measured using a peak flow meter. Length of stay in the recovery room, in the intermediate intensive care unit and in the hospital will be recorded. Time to reach post-anesthesia discharge criteria will be recorded. Patients will be contacted by telephone 2 times a day if hospital discharge occurs before 72 hours after surgery to assess their level of pain and analgesic intake, the presence of side-effects or complications and their satisfaction level towards pain management. This trial will also include a sub-study to be performed on ten human cadavers. The goal of the sub-study will be to assess the impact of the orientation of the bevel of the paravertebral block needle on the ease of insertion and positioning of the paravertebral catheter using ultrasound imaging.

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