Lipid Emulsion as a Treatment for Non-Local Anesthetic Poisoning in Animals: A Systematic Review and Meta-Analysis of Survival and Neurological Outcomes

A prior scoping review indicates that veterinarians use intravenous lipid emulsion (ILE) to treat poisoned animals, especially animals exposed to suspect neurotoxicants. The benefit of ILE in these cases remains uncertain. We conducted a systematic review and post hoc meta-analysis examining the use of ILE therapy in experimental animal models of neurotoxicosis and survival. We evaluated the relative risk of mortality using a random effects model. Neurological outcomes, including neuropathology, neurological signs, behavior, and anesthetic recovery, were assessed qualitatively. Of 3937 references screened, 38 met criteria for inclusion. In the global meta-analysis considering all toxicants and animal species, ILE treatment was associated with a lower risk of death (RR = 0.67; 95% CI, 0.48–0.93; p = 0.007). Possible publication bias was detected (Egger’s test, p = 0.005), and between-study heterogeneity was high (I2 = 74.5%). In a subgroup analysis excluding swine studies, ILE treatment was associated with reduced mortality (RR = 0.52; 95% CI, 0.33–0.82; p = 0.005); however, possible publication bias and high heterogeneity were present. A qualitative evaluation of neurological outcomes revealed heterogeneous results, incomplete reporting of studies resulting in risk of bias concerns in multiple domains, and small sample sizes. Exploratory meta-analysis of ILE demonstrated a reduction in mortality. Results were characterized by high heterogeneity, possible publication bias, methodological limitations, and very low certainty of evidence. Larger, adequately powered controlled clinical studies in naturally poisoned veterinary patients are needed.