Argon-Oxygen Mixture as a Multisystem Therapy after Circulatory Arrest: an Experimental Study

Cardiac arrest remains one of the leading causes of death worldwide. Even with successful resuscitation, patient outcomes are often poor due to post-resuscitation syndrome, which includes cerebral hypoxia, myocardial dysfunction, microcirculatory disorders, coagulation abnormalities, and systemic inflammation. Argon, an inert noble gas, has neuroprotective and cardioprotective properties, making it a promising candidate for early post-resuscitation therapy. The aim of the study was to evaluate the organoprotective properties of an argon-oxygen mixture when inhaled in the early post-resuscitation period for 2 hours after asphyxial circulatory arrest in rats. Materials and methods. A prospective randomized controlled experimental study was conducted on male Wistar rats ( n = 43) using an asphyxial circulatory arrest model. The animals were divided into three groups: sham-operated (SO, n = 12), circulatory arrest with resuscitation (CAR, n = 13), and circulatory arrest with resuscitation and two-hour inhalation of a 70%/30% argon-oxygen mixture in the post-resuscitation period (CAR + iAr, n = 18). Hemodynamics, microcirculation, blood gas composition, coagulation (low-frequency piezothromboelastography), neurological status, and biomarkers of organ damage were evaluated. Beclin-1 and caspase-3 expression was analyzed immunohistochemically. Results. Argon inhalation did not have a significant effect on systemic hemodynamics, but it was accompanied by improved tissue oxygenation and metabolism: a decrease in blood lactate ( p = 0.043), an increase in the p/F oxygenation index ( p = 0.001), and stabilization of microcirculation variability (Kv, σ). Statistically significantly increased expression of the Beclin-1 protein in the lungs, myocardium, and hippocampus reflected activation of autophagy. In the CAR + iAr group, there was an improvement in neurological status compared to CAR ( p = 0.02), a decrease in serum neuron-specific enolase ( p = 0.011), and a decrease in the number of caspase-3-positive cells ( p = 0.011), indicating a reduction in apoptosis and damage to the nervous tissue. Argon had a moderate anticoagulant and antiplatelet effect (coagulation drive intensity — CDI, and maximum clot firmness-MCF reduction), while maintaining normal processes of clot retraction and lysis. The electrophysiological parameters of the heart (QRS, QTc) varied within the physiological range, indicating the absence of pro-arrhythmic effects in argon. Conclusion. Early inhalation of argon-oxygen mixture after circulatory arrest has a multisystem protective effect: improves oxygenation and microcirculation, promotes activation of autophagy mechanisms in vital organs, reduces the severity of neuronal damage, and modulates blood clotting in some measure. Argon can be considered a promising therapeutic agent for post-resuscitation syndrome. Further clarification is needed to assess argon’s molecular mechanisms of action and long-term outcomes after its use.