Soman respiratory arrest

The effectiveness of pyridostigmine pretreatment may not be conclusive evidence against the importance of central mechanisms in respiratory arrest it appears that there is at least partial permeability of the blood-brain barrier to polar compounds such as pyridostigmine, specifically in the regions of the fourth ventricle and brainstem, where respiratory centers are located. In addition, an increase in blood-brain barrier permeability occurs rapidly after soman administration.1314 The key observation... 

The principal nerve agents. Sarin (GB), Soman (GD), Tabun (GA) and V-agents, are all organophosphorus compounds that inhibit the enzyme cholinesterase which is responsible for breaking down acetylcholine, a neurotransmitter. Nerve agents are toxic both by inhalation and by absorption through the skin. Symptoms include droohng, dilated pinhead pupils, headache, involuntary defecation, and a runny nose. Death is caused by cardiac arrest or respiratory failure. 

---