Single And Repeated Intrapleural Ropivacaine Administration: A Plasma Concentration And Pharmacodynamics Study

Background: Intrapleural analgesia has been increasingly recommended for postoperative analgesia after thoracic surgery. However, the analgesic effect provided by a single intrapleural administration is time limited. This study reports the efficacy and safety of repeated intrapleural 0.75% ropivacaine administration after thoracoscopic surgery.Methods: Twenty patients were randomly divided into two groups: a single administration group receiving a single intrapleural injection of 0.75% ropivacaine 15 mL (single administration group, SA group), and a repeated administration group with an intrapleural injection of 0.75% ropivacaine 15 mL every 4h for 4 doses (repeated administration group, RA group). The primary outcomes of this study were the peak plasma concentration of ropivacaine and 24h morphine consumption. The secondary outcomes were pain score, patient satisfaction, extubation time, hospital length of stay, and adverse reactions.Results: In SA group, the highest plasma concentration after intrapleural administration of 0.75% ropivacaine 15 mL was 1345 +/- 364 mu g/L. The highest plasma concentration in RA group after the fourth administration was 1864 +/- 492 mu g/L. The 24h morphine consumption in RA group was significantly less than that in SA group (9.0 +/- 5.66 vs 15.9 +/- 3.48 mg, P=0.004). The NRS scores at rest and while coughing of patients in RA group were significantly lower than those in SA group at 5, 9, 13, 17 and 24h after operation. The patients in RA group had higher satisfaction than those in SA group. There was no significant difference in postoperative adverse events, drainage tube placement days and hospital length of stay between the two groups.Conclusion: Repeated intrapleural administration with 0.75% ropivacaine, 15 mL every 4h for 4 doses after video-assisted thoracoscopic lobectomies, can provide a more durable and more effective analgesic effect than single intrapleural administration. Repeated intrapleural administration of ropivacaine is an effective postoperative method of analgesia resulting in higher patient satisfaction. Moreover, it was also able to keep the plasma concentration of ropivacaine within a possible safe range.