New Prospective Evaluation of Intraarterial Lidocaine During UAE
Pain control during the post-procedural period remains one of the persistent challenges of uterine artery embolization (UAE). Noel-Lamy et al present the results of a prospective randomized clinical trial comparing the efficacy of intra-arterial (IA) lidocaine infusion for pain control after UAE. Sixty patients were randomized to three arms, each with 20 patients: group A - 1% lidocaine infused with the first polyvinyl alcohol (PVA) vial during embolization followed by additional PVA vials to the embolization endpoint, group B – 1% lidocaine infused after PVA embolization to the embolization endpoint, and group C – control group for which saline was infused. The primary outcome was pain score using a validated scale at 4 hours post-UAE, which was significantly lower for the IA infusion groups (group A: infusion during PVA embolization, 28.6, SD: 24.5; group B: infusion post PVA embolization 35.8, SD: 22.6) versus control (59.4, SD: 30.3), p=0.001. This significant difference in pain levels dissipated by the 7 hour and 24 hour post-UAE time points, which were secondary outcomes. The in-hospital narcotic dose was significantly less for the lidocaine infusion groups (group A: 8.5 mg, SD: 7.4; group B: 11.1 mg, SD: 7.6) compared to control (17.4 mg, SD: 10.5), p=0.006. The 24-hour narcotic dose was also significantly less for the lidocaine infusion groups (group A: 11.1, SD: 9.6; group B: 16.3, SD: 11.5) compared to control (21, SD: 10.5), p=0.021. No significant difference in time to discharge was observed between groups. On 3-month post-UAE MRI, there was a significantly lower rate of complete infarction in group A (38.9%) versus group B (77.8%) or control (75%), p=0.045. There were no serious adverse events in any of the treatment arms.
This study by Noel-Lamey et al provides a well-designed, prospective evaluation to confirm the efficacy of IA lidocaine infusion for pain control following UAE. The authors used a validated pain scale to provide a more reliable and replicable endpoint measure than previous studies using non-validated pain scores. Their results suggest that IA lidocaine infusion does provide significant analgesic benefit during the immediate post-procedural period, to a degree that is sufficient to reduce the oral narcotic requirement in the first 24 hours. It is important to note that the standard deviations for both the pain scale measures and the narcotic doses were relatively wide, perhaps reflecting inherent differences in pain perception between patients. Interestingly, the degree of analgesia was not significantly different between lidocaine infusion with initial embolization or following embolization, even as the authors acknowledged that most of the infusion likely refluxed from the uterine arteries in the latter approach. Previous studies have shown severe vasospasm with lidocaine infusion during embolization, which was not observed in this study, likely due to usage of a lower lidocaine dose. However, there was a 50% lower percentage of complete fibroid infarction at 3 months post-UAE in the group that received lidocaine with initial embolization versus post embolization, suggesting that distal vasospasm occurred and partially interrupted embolic delivery. Based on these findings, the authors concluded that lidocaine infusion after embolization is preferable to during embolization. Limitations to this study included the lack of investigator blinding to the method of lidocaine injection, narcotic administration by a nurse rather than patient controlled analgesia, and relatively small sample size. Nonetheless, while additional investigation should be done, the study effectively confirms the efficacy and safety of IA lidocaine infusion for UAE pain control and clarifies the optimal infusion timing relative to embolization.
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Noel-Lamy M, Tan KT, Simons ME, Sniderman KW, Mironov O, Rajan DK. Intraarterial Lidocaine for Pain Control in Uterine Artery Embolization: A Prospective, Randomized Study. J Vasc Interv Radiol 2016. Article in press.
Jeffrey Forris Beecham Chick, MD, MPH, DABR
Assistant Professor of Vascular and Interventional Radiology
Vice Quality Assurance and Safety Officer
University of Michigan Health Systems
James X. Chen, MD
Resident in Radiology
Hospital of the University of Pennsylvania