Systemic Asphyxiant Chemical-Warfare Agents By James M Madsen, MD, MPH, U S.Army Medical Research Institute of Chemical Defense (USAMRICD) Reviewed / Revised Jan 2023 View Patient Education Pathophysiology Symptoms and Signs Diagnosis Treatment Systemic asphyxiants are a type of chemical-warfare agent and include Cyanide compounds Hydrogen sulfide Systemic asphyxiants have also been called blood agents because they are systemically distributed via the blood.