The effect of intravenosus lipid emulsion treatmenton motor block duration in rats with sciatic nerve block

Objective: Peripheral nerve blocks are used effectively in both surgical anesthesia management and multimodal analgesia strategies. Intravenous lipid emulsion (ILE), which is used to treat local anesthetic toxicity, may shorten the duration of local anesthesia-induced blockade. In this experimental study, we aimed to compare the effects of intravenously administered ILE and Normal Saline (NS) on motor block duration in rats undergoing sciatic nerve block via a percutaneous technique.Methods: This experimental study was conducted in a randomized, double-blind manner at Ondokuz Mayıs University Experimental Animals Research and Application Center (DEHAM). Twenty male Wistar Albino rats underwent unilateral sciatic nerve block. After randomization, the rats were divided into two groups: ILE (Group L) and Normal Saline (Group S). Group S received 7.5 ml/kg intravenous normal saline, while Group L received 7.5 ml/kg of a 20% lipid solution. Motor, sensory, and deep sensory block durations were assessed at 0, 1, 5, and 10 minutes post-procedure, and then every 10 minutes until the block resolved, by a blinded investigator. The primary outcome of this study was the time to reversal of motor block. Additionally, sensory and deep sensory block durations were evaluated as secondary outcomes.Results: A total of 20 male Wistar Albino rats with an average weight of 355 grams and normal motor activity were included in the study (Group S: 10, Group L: 10). The time to motor function recovery after sciatic nerve block was 94 ± 6.9 minutes in Group S and 36 ± 8.4 minutes in Group L. There was a statistically significant difference between the two groups regarding the time to reversal of the sciatic block (P < 0.05). The mean sensory block duration was 104 ± 5.1 minutes in Group S and 45 ± 9.7 minutes in Group L, while the mean deep sensory block duration was 104 ± 11.7 minutes in Group S and 43 ± 11.5 minutes in Group L. A statistically significant difference was also found between the two groups in terms of sensory and deep sensory block resolution times (P < 0.05).Conclusion: In this study, we observed that ILE administration shortened the motor block duration in rats undergoing sciatic nerve block via a percutaneous approach. Additionally, ILE administration also reduced sensory and deep sensory block durations. Although the data suggest that ILE shortens block duration in peripheral nerve blocks, more comprehensive randomized controlled trials are needed to guide clinical applications.