A significant and potentially severe complication of medication administration
Must consider this scenario any time patient begins complaining of paresthesias or pain distal to IV site
Self-inflicted cases are also being described in patients with IVDA
Obesity
Hypotension
Procedurally difficult situations (ie. agitated patient, back of ambulance)
Aberrant vascular anatomy
Is often multifactorial and dependent upon type of medication administered. Theories include NE induced vasospasm, crystal formation, venous constriction, lipid solubility, direct cytoxicity, endothelial damage and high osmolality.  All pathways suggest the primary mediator of tissue injury is thrombosis
Benzodiazepines
Barbiturates
Propofol
Penicillins
Amphetamines
Phenothiazines
Phenytoin
Heroin
Tubocurarine
Atrcurium
TPN
NaHCO3
Hypertonic Dextrose (D50)
Unintentional intra-arterial injection
Skin and soft tissue infections
Blunt cardiac injury
DVT
Hemorrhage of AV fistula
CT contrast media extravasation
Missile embolism
Allergic reaction