Difference Between Infiltration and Extravasation in PIVs
The key distinction is based on the type of substance leaked into surrounding tissue: infiltration occurs when a nonvesicant solution or medication leaks into tissue, while extravasation specifically refers to leakage of vesicant medications that have tissue-damaging potential. 1
Core Definitions
Infiltration is the inadvertent administration of a nonvesicant solution or medication into the subcutaneous or subdermal tissues surrounding the IV catheter site. 1
Extravasation is the process by which vesicant drugs accidentally leak into the surrounding tissue, with potential for causing significant tissue damage including necrosis, ulceration, and permanent injury. 2
Critical Clinical Distinction
The fundamental difference lies in the damage potential of the infused substance, not the mechanism of leakage:
Infiltration involves nonvesicant fluids (normal saline, lactated Ringer's, dextrose solutions) that typically cause localized swelling, discomfort, and coolness but rarely result in permanent tissue damage. 1
Extravasation involves vesicant or irritant medications (chemotherapy agents, vasopressors, hypertonic solutions, certain antibiotics) that can cause severe tissue injury through multiple mechanisms including vasoconstriction, pH-mediated damage, osmolar injury, and direct cytotoxic effects. 3
Mechanisms of Tissue Injury in Extravasation
Extravasated agents cause harm through distinct pathophysiologic mechanisms:
Vasoconstriction-mediated injury occurs with vasopressors and calcium-containing solutions, causing tissue ischemia and necrosis. 3
pH-mediated injury results from acidic agents (promethazine, amiodarone, vancomycin) causing cellular desiccation, or basic agents (phenytoin, acyclovir) causing deeper tissue penetration and hydroxide ion damage. 3
Osmolar-mediated injury occurs with hypertonic solutions causing osmotic shifts across cellular membranes and subsequent cellular damage. 3
Cytotoxic mechanisms involve direct cellular destruction by chemotherapeutic agents. 2
Clinical Consequences and Risk Stratification
Both complications can result in serious outcomes, but extravasation carries significantly higher risk:
Infiltration is often viewed as a routine complication but should not be dismissed, as even nonvesicant fluids can cause compartment syndrome, particularly in high-risk patients (ICU admission, intubated/sedated patients). 4, 5
Extravasation may require surgical intervention, result in large scars, cause limitation of function, amputation, or complex regional pain syndrome requiring long-term pain management. 1
Major adverse events (full-thickness injury requiring operative management, compartment syndrome) occurred in 4.4% of infiltration cases, with ICU admission and current intubation status significantly associated with adverse outcomes. 4
Classification of Extravasated Drugs
Extravasated drugs are classified by tissue damage potential:
Vesicants: Cause tissue necrosis and blistering (anthracyclines, vinca alkaloids, nitrogen mustards). 2
Irritants: Cause pain and inflammation without necrosis (oxaliplatin, etoposide). 2
Nonvesicants: Minimal tissue damage potential. 2
Common Pitfall to Avoid
Do not assume infiltration is benign simply because the infused substance is nonvesicant. Large-volume infiltrations, particularly in patients with impaired sensation or communication (intubated, sedated, elderly, pediatric), can progress to compartment syndrome and require surgical intervention. 4, 1 The volume of fluid extravasated and patient-specific risk factors (impaired circulation, coagulation abnormalities, sensory deficits) significantly influence outcomes regardless of whether the event is classified as infiltration or extravasation. 2, 4