A randomized comparison of plasma levobupivacaine concentrations following thoracic epidural analgesia and subpleural paravertebral analgesia in open thoracic surgery
2020-02-13T06:41:28Z (GMT) by
Continuous subpleural paravertebral analgesia may be an alternative to thoracic epidural analgesia following open thoracic procedures. Data about the pharmacokinetic profile of levobupivacaine after administration to the subpleural paravertebral space is unknown. This randomized study investigated differences in plasma levobupivacaine levels between thoracic epidural and subpleural paravertebral administrations. Forty-four patients scheduled for lobectomy or pneumonectomy were randomly allocated into two groups. A thoracic epidural catheter was inserted at the T5-T7 level preoperatively in one group, while the other group had a catheter inserted by the surgeon under direct vision in the paravertebral space at the level of the thoracotomy. A bolus of 0.25% levobupivacaine at 0.5 mg per kg of body weight was administered before the closure of the thoracotomy. The primary outcome was the plasma level of levobupivacaine at 30, 60 and 120 mins. Based on these results, pharmacokinetic modeling was performed. Secondary outcomes included the quality of pain relief, the need for additional systemic analgesia, hemodynamic instability, complication rates and mobility of the patients. Levobupivacaine plasma levels were without statistical difference 30 min after administration – 0.389 mg.L-1 in the epidural and 0.318 mg.L-1 in the subpleural group (p=0.11). Plasma levels were significantly lower in the subpleural group at 60 (p=0.026) and 120 mins (p=0.006). Maximum concentrations and areas under the curve were higher in the epidural group. The time to achieve maximum plasma concentration was similar in both groups – 27.6 versus 24.2 minutes. The intensity of pain was higher in the subpleural group only at two hours (p=0.03), while the need for additional systemic analgesia was similar in both groups. There was no difference between the groups in postoperative complications, mobility and the incidence of hypotension. Systemic levels of levobupivacaine were low in both thoracic epidural and subpleural paravertebral analgesia after bolus administration of local anesthetic and no symptoms of systemic local anesthetic toxicity were recorded. Dosage of 0.5 mg.kg-1 should be sufficiently safe and effective for providing postoperative analgesia in open thoracic surgery.