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.
However, there are different ways cancer can cause SVCS. A tumor in the chest may press on the superior vena cava. A tumor may grow into the superior vena cava, causing a blockage. If cancer spreads to the lymph nodes surrounding the superior vena cava, the lymph nodes may enlarge and press on or block the vein.