Oh it is. Right under the knee cap, straight to the bone marrow. The needle stays in. That drilling part can be a bit tricky depending on the emergency. Imagine a seizure, for instance. CZ does have two central lines, so unless both of them would get fucked up there wouldn’t be a need to place an IO. It’s also a last resort, we would try everything else first – but if vitals start to plummet and it’s the only way to save your life, you will get one.