A Phase 3 interventional study of Аrgon-oxygen breathing mixture and Nitrogen-oxygen breathing mixture in Carotid Artery Disease and Carotid Artery Stenoses, sponsored by Negovsky Reanimatology Research Institute. Recruiting at 2 sites in Russia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-18.
Sponsored by Negovsky Reanimatology Research Institute · Phase 3, Interventional, and Prevention
Currently, over 400,000 reconstructive surgeries on carotid arteries are performed annually worldwide, including carotid endarterectomy (CEA) and carotid stenting. These interventions have proven effective in preventing ischemic stroke in patients with hemodynamically significant carotid artery stenoses. However, even following a technically successful procedure, the risk of perioperative ischemic brain injury persists. According to meta-analyses, one in five patients exhibits covert ("silent") strokes after reconstructive interventions, with their frequency being ten times higher than that of clinically manifest events. Such lesions are associated with cognitive decline and an increased risk of dementia. An additional risk factor is the "no-reflow" phenomenon-an impairment of microcirculatory reperfusion that occurs even after the restoration of macrovascular blood flow, thereby limiting the effectiveness of surgical revascularization.
Cognitive disorders and postoperative delirium, observed in 15-30% of patients after CEA, adversely affect rehabilitation and long-term prognosis. To date, there are no reliable pharmacological strategies to prevent these complications.
In this context, inert gases have attracted significant interest as potential neuroprotective agents. Xenon, despite its proven efficacy, is limited by high cost and challenges in industrial production. Argon, in contrast, is accessible, safe, and technologically straightforward to administer. In preclinical models of stroke and ischemia-reperfusion, argon has demonstrated pronounced anti-apoptotic, anti-inflammatory, and antioxidant effects, mediated through the regulation of TLR2/4-, ERK1/2-, Nrf2-, and NF-κB-dependent signaling pathways. Its ability to suppress microglial activation towards the M1 phenotype and inhibit the NLRP3 inflammasome has been noted, which reduces neuroinflammation and decreases the volume of secondary neuronal damage. Short-term argon inhalation in healthy volunteers has shown a favorable safety profile with no adverse effects on cerebral hemodynamics.
Thus, it is highly relevant to clinically test the hypothesis that perioperative inhalation of an argon-containing gas mixture can reduce the incidence of ischemic brain injuries and cognitive impairments in patients undergoing CEA.
248 studies on the registry are indexed under Carotid Artery Diseases; 56 are open to participants now.
This study's planned enrollment of 100 is below the median of 120 across 118 interventional studies indexed under Carotid Artery Diseases.
Browse Carotid Artery Diseases studies →Negovsky Reanimatology Research Institute is the lead sponsor of 10 studies on the registry; 2 are open to participants now.
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Exclusion Criteria:
Perioperative inhalation of an argon-oxygen mixture (70% argon, 30% oxygen)
Drug: Аrgon-oxygen breathing mixture
Perioperative inhalation of an nitrogen-oxygen mixture (70% nitrogen, 30% oxygen)
Drug: Nitrogen-oxygen breathing mixture
Patients receive a course of inhalations with an argon-oxygen mixture according to the following protocol: 60 minutes on day 1 prior to surgery, 60 minutes one hour before being transferred to the operating room, and 60 minutes on the first postoperative day
Patients receive a course of inhalations with an nitrogen-oxygen mixture according to the following protocol: 60 minutes on day 1 prior to surgery, 60 minutes one hour before being transferred to the operating room, and 60 minutes on the first postoperative day
Incidence of postoperative delirium
Number of patients with even one positive confusion assessment method for the intensive care unit or 3-minute confusion assessment method
Time frame: 30 days
Incidence of emergence delirium
Number of patients with positive the confusion assessment method for the intensive care unit as soon as they reach Aldrete score of 9 points
Time frame: 30 days
Incidence of postoperative agitation
Richmond agitation-sedation scale more or equal +2 evaluated from the end of volatile anesthetic supply to the moment when a patient reaches Aldrete score of 9 points Richmond agitation-sedation scale: minimum value = -5 (Unarousable - no response to voice or physical stimulation) maximum value = +4 (Combative - overtly combative or violent; immediate danger to staff) Adequate patients have the results of Richmond agitation-sedation score equal 0 (Alert and calm; Spontaneously pays attention to caregiver)
Time frame: 30 days
Duration of postoperative delirium
30 days - number of days in which patient had positive confusion assessment method for the intensive care unit or 3-minute confusion assessment method
Time frame: until 1 month after surgery
Incidence of cognitive dysfunction
reduction of ≥1 standard deviation in the Montreal Cognitive Assessment (MoCA) total z-score compared to the preoperative assessment
Time frame: 30 days
Incidence of overt stroke
Number of overt strokes
Time frame: 30 days
Incidence of covert stroke
Number of covert strokes
Time frame: 30 days
Length of stay in the intensive care unit
Number of days in intensive care unit
Time frame: 30 days
Length of hospitalization
Number of days in hospital
Time frame: 30 days
Serum level of S100 beta protein
Serum level of S100 beta protein
Time frame: 2 days after surgery
Serum level of neuron-specific enolase
Serum level of neuron-specific enolase
Time frame: 2 days after surgery
Serum level of interleukin-6
Serum level of interleukin-6
Time frame: 2 days after surgery
Plan to share: No — Decision of the local ethics committee
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Negovsky Reanimatology Research Institute