death The patient is susceptible to infection due to lack of granulocytes and because pathogens can readily enter the body across the damaged GI tract lining At dose levels of more than 50 Gy, the cardiovascular/neurovascular syndrome predominates There is almost immediate nausea, vomiting, prostration, hypotension, ataxia, and convulsions The permeability of blood vessels increases and there is brain edema and hypotension caused by the difficulty of maintaining a normal intravascular space Death usually occurs within to days TABLE 90.14 ACUTE RADIATION SYNDROME—SYMPTOMS Prodromal (0–2 a ) Latent (2–20 a ) Fatigue Nausea and vomiting Generally asymptomatic Sepsis Bleeding Diarrhea Diarrhea Headache Dizziness a Days after exposure Manifest illness (21–60 a)