Excess dilation of vessels.
Anaphylactic Shock (chemicals causing vasodilation during an allergic rxn)
Septic Shock (hypotension unresponsive to fluids, metabolic acidosis, acute encephalopathy oliguria, and/or coag probs)
Neurogenic Shock (disruption in the nervous system affects the vasomotor center in the medulla, disrupting sympathetic nerve impulses. This causes vasodilation.)