Temporary nerve block for pain management in thermal ablation of the liver

This study is to assess whether a temporary nerve block performed immediately prior to thermal ablation for treatment of hepatic tumors reduces the need for IV medication induced conscious sedation during the ablation. Retrospective study performed between September 2015 and July 2016 during which some patients had received a celiac plexus or hepatic hilar nerve block for periprocedural pain control and others did not, based on operator ease and experience at performing the blocks. All patients having had ablation performed under conscious sedation rather than general anesthesia were included. Use of IV sedation during the procedure is provided by nursing staff following a standard protocol which includes 1 mg midazolam and 50 mcg fentanyl prior to starting the procedure. Exclusion criteria were patients in which IV sedation use was not recorded adequately or was not available. Nerve blocks were performed by the IR just before the thermal ablation. The control group of patients was those that did not receive a block. Consumption of fentanyl and midazolam recorded during the procedure were compared between both groups. 23 patients fit the inclusion and exclusion criteria. 10 did not receive any nerve block and 13 received a nerve block: 7 patients had a celiac plexus block and 6 patients had a hepatic hilum plexus block. Similar average tumor characteristics, Ablation time, and distance from tumor to capsule between groups. The average consumption for midazolam was 1.68 mg ( ± 0,59 SD) in patients who receive a nerve block and 2.55 mg ( ± 0,8 SD) in patients who did not (p = 0.013). The consumption of fentanyl in patients who received a nerve block was 123 μg ( ± 52 SD) and 195 μg ( ± 88 SD) in those who did not (p = 0.035). Only one of the patients who received a block had a self resolving bradycardia with no clinical implication. No major complications occurred in the nerve block group. Within the limits of a retrospective study, data demonstrates that hepatic hilum or celiac plexus blocks are safe and feasible tools to reduce use of IV sedation needed during liver thermal ablation. A prospective study would be needed to confirm this.