The following definitions are taken from the glossary of the 2011 Infusion Nursing Standards of Practice.
- Vesicant. An agent capable of causing blistering, tissue sloughing, or necrosis when it escapes from the intended vascular pathway into surrounding tissue.
- Irritant. An agent capable of producing discomfort or pain along the internal lumen of the vein.
These definitions indicate a major difference of where the damage is taking place. For a vesicant, the damage is occurring in the subcutaneous tissue OUTSIDE of the vein. For irritants, the damage is occurring to the vein wall INSIDE the lumen.
Vesicants cause tissue damage that may OR may not require surgical intervention. Notice in the definition the use of the word “or” – blistering, tissue sloughing OR necrosis. Blistering and tissue sloughing are tissue damage but necrosis may not be present. Time is required to heal the area, hopefully without any permanent tissue destruction. Necrosis requires surgical debridement and maybe even skin grafting to allow for complete healing. Vesicants produce this entire range of tissue injury with the damage occurring to the subcutaneous tissue at or near the point of where the fluid is escaping from the vein. This can be at the point of vein puncture or the catheter’s tip location or both.
Irritants cause phlebitis (vein inflammation) and thrombophlebitis (thrombus plus inflammation), so the damage is occurring inside the vein lumen. This inflammatory process can produce severe edema but there is no infusing fluid leaking from the vein into the subcutaneous tissue. When peripheral catheters are used for infusion, this is occurring in superficial veins, thus the diagnosis of superficial thrombophlebitis. When it occurs with a PICC or other CVAD, it is most often a deep vein thrombophlebitis.
The term, “extravasation” is referring to the leakage of vesicant fluid/medications into the subcutaneous tissue. But this term is not used when the event is from an irritant inside the vein lumen.
Signs and symptoms often overlap between these 2 complications. It may be difficult for staff nurses to distinguish the difference and this is where the knowledge and skill of an infusion nurse is required.