The abbreviation IO stands for which route?

• A. Intraosseous
• B. Intravenous
• C. Intramuscular
• D. Subcutaneous

Answer: (A)

IO stands for intraosseous, a route that delivers fluids or medications directly into the bone marrow so they reach the central circulation quickly, especially when venous access is difficult. This is different from intravenous, which delivers into a vein; intramuscular, which goes into muscle tissue; and subcutaneous, which goes into the fatty tissue under the skin. In emergencies, intraosseous access allows rapid administration of drugs and fluids when IV access can't be obtained promptly, typically using sites like the proximal tibia or humerus. Most medications that can be given IV can also be given intraosseously, though this is usually a temporary measure until reliable IV access is established.