latent, dormant, quiescent, potential mean not now showing signs of activity or existence. latent applies to a power or quality that has not yet come forth but may emerge and develop. dormant suggests the inactivity of something (as a feeling or power) as though sleeping.
However, H1N1 can progress quickly, so it is uncertain if knowing the patient had influenza would have prevented their rapid progression. Vasopressors can cause tissue ischemia if used in high doses, and I have seen necrosis of digits due to vasopressors. That being said, I have never seen limb amputations due to vasopressor use, but it could happen.
Vasopressin is a peptide hormone that increases water permeability of the kidney's collecting duct and distal convoluted tubule by inducing translocation of aquaporin-CD water channels in the plasma membrane of collecting duct cells. It also increases peripheral vascular resistance, which in turn increases arterial blood pressure.