Subpleural block is less effective than thoracic epidural analgesia for post-thoracotomy pain

Abstract

Thoracic epidural and paravertebral blocks provide adequate analgesia for postoperative thoracotomy pain. Both procedures are usually performed percutaneously with considerable failure rates. A subpleural catheter placed in the space posterior to the parietal pleura and alongside the paravertebral area may provide superior postoperative pain relief. To compare subpleural analgesia with thoracic epidural analgesia in patients undergoing thoracotomy. Randomised, double-blind study. A tertiary care University Medical Centre between 26 June 2008 and 21 March 2011. Forty-two patients scheduled for elective posterolateral thoracotomy. Patients with American Society of Anesthesiologists physical status ≥4, with a previous history of thoracotomy, on chronic pain medications or with a contraindication to receiving local anaesthetics or thoracic epidural block were excluded from the study. Patients were randomised to receive either subpleural analgesia or thoracic epidural analgesia for 24-h post-thoracotomy pain control. A visual analogue scale was used to assess pain at rest and on coughing during the first 24 h postoperatively and the incidence of hypotension was recorded. Patients who received subpleural analgesia had higher visual analogue scores at rest and on coughing than those who received thoracic epidural analgesia. Seven patients who started with subpleural analgesia were treated with thoracic epidural analgesia at a mean (SD) of 3.9 (4.8) h. The remaining 14 patients had a median (IQR [range]) visual analogue score of 5 cm (4-5 [3-6]) at rest and were maintained on subpleural analgesia until the end of the study. The visual analogue score at rest was <7 cm in all 21 patients who received thoracic epidural analgesia and none was switched to subpleural analgesia during the study. None of the patients in the subpleural analgesia group experienced hypotension compared with five of the 21 patients in the thoracic epidural analgesia group (P=0.047). Thoracic epidural analgesia is superior to subpleural analgesia in relieving post-thoracotomy pain.