Post-thoracotomy regional analgesia
April 19, 2010 1 Comment
Blog Post by Dr Darcy M Pearson FRCA, Specialty Trainee in Anaesthesia & Intensive Care, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK and Dr Stephen T Webb MB BCh BAO FRCA EDIC, Consultant in Anaesthesia & Intensive Care Medicine, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK
Inadequate postoperative pain relief after thoracotomy increases the risk of respiratory complications and chronic post-surgical pain. A number of regional analgesic techniques may be used for post-thoracotomy analgesia including intercostal,intrapleural, extrapleural, paravertebral, intrathecal and epidural analgesia. Extrapleural and paravertebral techniques may be performed by percutaneously or under direct vision and may involve single injections or continuous infusions.
Thoracic epidural analgesia (TEA) is the most commonly used technique for post-thoracotomy analgesia. In comparison to systemic opioid analgesia, TEA has been shown to provide improved pain relief, reduced surgical stress response and earlier mobilization. A large meta-analysis of 141 trials comparing central neuraxial blockade with systemic opioid analgesia for general, orthopaedic, urological and vascular surgical procedures showed a reduction in stroke, myocardial infarction, pulmonary embolism, pneumonia and 30 day mortality. However, two subsequent multicentre randomized controlled trials have failed to reproduce these benefits. The incidence of technical failure for TEA is not insignificant and complications include hypotension, urinary retention, motor block, dural puncture, infection, bleeding and nerve injury. The recent Royal College of Anaesthetists 3rd National Audit Project ‘Major complications of central neuraxial block’ estimated the incidence of permanent harm related to perioperative epidural analgesia to be between approximately 1 in 5,800 and 1 in 12,000.
Extrapleural analgesia is an alternative to thoracic epidural analgesia and may be particularly useful if sepsis or coagulopathy prevents epidural insertion. The technique involves surgical placement of a catheter into an extrapleural pocket created between the parietal pleura and chest wall and tunnelling of the catheter into the paravertebral space. The paravertebral space contains the ventral primary rami, intercostal nerves, dorsal rami and sympathetic chain. The delivery of local anaesthetic through the extrapleural catheter into the paravertebral space produces unilateral chest wall analgesia.
Large trials comparing the efficacy and safety of paravertebral analgesia and TEA are lacking however a meta-analysis including over 500 patients showed a lower incidence of pulmonary complications, nausea, vomiting, urinary retention and hypotension with paravertebral analgesia, without any differences in pain scores or the need for supplementary analgesia. In addition, the incidence of technical failure with paravertebral analgesia was found to be lower than with TEA. An adequately powered randomised controlled trial to compare the efficacy and safety of the two techniques is awaited.
For more information, please see Core Topics in Cardiac Anaesthesia, 2nd edition, edited by Joseph Arrowsmith and Jonathan Mackay, and Core Topics in Thoracic Anesthesia, edited by Cait P. Searl, and Sameena T. Ahmed, published by Cambridge University Press.