Inhaled Gases as Therapies for Post-Cardiac Arrest Syndrome: A Narrative Review of Recent Developments

Authors
Journal
Frontiers in Medicine
Year
DOI
10.3389/fmed.2020.586229
Study Type
clinical
Peer Reviewed
Yes
Country
United States
Health Condition
Post-cardiac arrest syndrome (PCAS)
Body System
Cardiovascular system

TL;DR

When someone's heart stops and they're brought back to life, their brain can still get seriously damaged from the lack of oxygen. Scientists found that breathing in certain special gases like hydrogen, nitric oxide, and xenon can help protect the brain and reduce this damage, which could help more people survive cardiac arrest without permanent brain injury.

Key Finding

Inhaled molecular hydrogen, nitric oxide, and xenon show cytoprotective effects against post-cardiac arrest complications through multiple mechanisms including reduction of oxidative stress and preservation of mitochondrial function.

Summary

This review examined how inhaled gases—including molecular hydrogen, nitric oxide, and xenon—might help treat complications that occur after cardiac arrest and resuscitation. When the heart stops, the brain and body don't get oxygen, and when blood flow is restored, it can cause additional damage through a process called reperfusion injury. The review found that these gases appear to protect cells by reducing harmful oxidative stress (cellular damage from unstable molecules), decreasing inflammation, and helping cells' energy-producing structures (mitochondria) work better. However, the authors note that more research is needed before these treatments can be used in regular patient care.

Practical Takeaway

This is a review article summarizing existing research rather than a new study, and it focuses on inhaled hydrogen gas in a medical emergency setting—not hydrogen water for general wellness. While early evidence suggests these inhaled gases may help protect the brain after cardiac arrest, the authors emphasize that much more research is needed before clinical use. This review does not provide evidence supporting hydrogen water consumption for health purposes.

Abstract

Despite recent advances in the management of post-cardiac arrest syndrome (PCAS), the survival rate, without neurologic sequelae after resuscitation, remains very low. Whole-body ischemia, followed by reperfusion after cardiac arrest (CA), contributes to PCAS, for which established pharmaceutical interventions are still lacking. It has been shown that a number of different processes can ultimately lead to neuronal injury and cell death in the pathology of PCAS, including vasoconstriction, protein modification, impaired mitochondrial respiration, cell death signaling, inflammation, and excessive oxidative stress. Recently, the pathophysiological effects of inhaled gases including nitric oxide (NO), molecular hydrogen (H2), and xenon (Xe) have attracted much attention. Herein, we summarize recent literature on the application of NO, H2, and Xe for treating PCAS. Recent basic and clinical research has shown that these gases have cytoprotective effects against PCAS. Nevertheless, there are likely differences in the mechanisms by which these gases modulate reperfusion injury after CA. Further preclinical and clinical studies examining the combinations of standard post-CA care and inhaled gas treatment to prevent ischemia-reperfusion injury are warranted to improve outcomes in patients who are being failed by our current therapies.