When is intraosseous access preferred over IV in a deployed setting?

• A. When IV access is difficult or time-consuming due to shock or poor peripheral veins; IO is rapid and reliable in austere conditions
• B. When skilled personnel available
• C. Only after IV success
• D. In all patients regardless

Answer: (C)

In a deployed, austere setting the main reason to choose intraosseous access is when IV access is difficult or time-consuming due to shock or poor peripheral veins. In severe blood loss or shock, vessels constrict and veins can collapse, making repeated IV attempts slow and often futile. The intraosseous route taps into the bone marrow's venous sinusoids, giving rapid, reliable access to the central circulation without depending on peripheral veins. This allows fluids and medications to be delivered quickly, which is crucial when every second matters in resuscitation.

This approach is not about having more skilled personnel or waiting until an IV attempt has succeeded. It is about avoiding delays by opting for a fast, dependable route as soon as IV access is unlikely or time-consuming. It’s not used universally for all patients; there are situations where IO isn’t appropriate (injury to the bone, infection at the insertion site, or specific contraindications), but in austere, time-critical scenarios, it’s the preferred option whenever IV access would be slow or unreliable.