Xenon and Argon as Neuroprotective Treatments for Perinatal Hypoxic-Ischemic Brain Injury: A Preclinical Systematic Review and Meta-Analysis.

Xenon and argon are currently being evaluated as potential neuroprotective treatments for acquired brain injuries. Xenon has been evaluated clinically as a treatment for brain ischemia with equivocal results in small trials, but argon has not yet undergone clinical evaluation. Several preclinical studies have investigated xenon or argon as treatments in animal models of perinatal hypoxic-ischemic encephalopathy (HIE). A systematic review of MEDLINE and Embase databases was performed. After screening of titles, abstracts, and full text, data were extracted from included studies. A pairwise meta-analysis of neuroprotective efficacy was performed using a random effects model. Heterogeneity was investigated using subgroup analysis, funnel plot asymmetry, and Egger's regression. The protocol was prospectively registered on PROSPERO (CRD42022301986). A total of 21 studies met the inclusion criteria. The data extracted included measurements from 1591 animals, involving models of HIE in mice, rats, and pigs. The meta-analysis found that both xenon and argon had significant (P < .0001) neuroprotective efficacies. The summary estimate for xenon was 39.7% (95% confidence interval [CI], 28.3%-51.1%) and for argon it was 70.3% (95% CI, 59.0%-81.7%). The summary effect for argon was significantly (P < .001) greater than that of xenon. Our results provide evidence supporting further investigation of xenon and argon as neuroprotective treatments for HIE.