SUMMARY
Pain after thoracotomy is very severe, probably the most severe pain experienced after surgery. It is also unique as this pain state has multiple implications, including respiratory failure due to splinting; inability to clear secretions by effective coughing, with resulting pneumonia; and facilitation of the often incapacitating chronic pain: the post-thoracotomy pain syndrome. A thoracotomy requires a very painful incision, involving multiple muscle layers, rib resection, and continuous motion as the patient breathes.
Treatment of acute post-thoracotomy pain is particularly important not only to keep the patient comfortable but also to minimize pulmonary complications. Many methods of pain management, each with attendant problems, have been tried with varied success, for example: intercostal nerve block, intrapleural analgesia, cryo-analgesia, lumbar epidural, thoracic epidural, paravertebral block, IV narcotics, intrathecal or epidural narcotics, NSAIDS and transcutaneous nerve stimulation. There are different analgesic modalities for management of post-thoracotomy pain. There are systemic methods which includes infusion and patient-controlled analgesia (PCA) or regional techniques that mainly rely on epidural, intrathecal or paravertebral blocks. Other techniques range from intercostal nerve block to cryoprobeneurolysis .
Intercostal nerve blockade is used routinely at some centers either by single injection of local anesthetics in multiple intercostal nerves before closure of thoracotomy incision or catheter infusion. However, single-shot intercostal nerve blocks with local anesthetic generally do not provide effective long-term analgesia and frequently have to be repeated.
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Summary
The thoracic paravertebral block is another technique for management of post-thoracotomy pain by injecting local anesthetic in the vicinity of the thoracic spinal nerves emerging from the intervertebral foramen with the resultant ipsilateral somatic and sympathetic nerve blockade. The resultant anesthesia or analgesia is conceptually similar to a "unilateral" epidural anesthesia.
The addition of adjunctive analgesics, such as fentanyl and clonidine, to local anesthetics has been shown to enhance the quality and duration of sensory neural blockades, and decrease the dose of local anesthetic and supplemental analgesia.
Dexmedetomidine is a highly selective α2-adrenorceptor agonist recently introduced to anesthesia; it produces a dose-dependent sedation, anxiolysis, and analgesia (involving spinal and supraspinal sites) without respiratory depression. |
