Life Span Development and Patients with Special Challenges

1. Age changes where the access goes

Start with the vein. A vein in a young child or a fragile older adult is not the same target as a vein in a healthy adult. So the catheter you pick has to follow the vein, not the protocol. A fragile or pediatric vein takes a smaller-bore catheter. Large-bore is for volume resuscitation, and hanging the right fluid through a catheter the vein cannot tolerate is still a failed line. Sizing itself lives in IV Therapy and Fluid Administration — this lesson is about which site you're allowed to use and why.

Older adults' veins are thin, mobile, and sit in loose tissue. So expect the vein to roll while you're cannulating it, and expect the site to infiltrate more readily once you're moving. That's why you reassess the site more often in this patient than you would in a younger one.

Intraosseous access works differently. You're not picking a vein — you're picking a bone, and a bone can carry contraindications you can see and feel before you ever place the needle. A fracture at the site rules it out. An infection at the site rules it out. And prior orthopedic hardware, like a prosthetic joint, rules it out too — the needle can't seat in bone that's been replaced with metal.

Memory cue — before an IO, ask what is already in that bone. A break, an infection, or hardware means the other leg.

Any of those three redirects you to another site, most often the contralateral limb. The wrong response is trying the same site anyway at a reduced flow rate — a contraindicated site doesn't get safer because you go slower.

One more site rule, and this one's about scope, not anatomy. The access already in the patient is not yours to use. Long-term vascular access devices, implanted ports, central lines, and dialysis access are Paramedic-level to access or monitor under the national scope model. So you establish your own line instead of using theirs. The scope boundary itself is covered in Specialized Transport Considerations, and the dialysis fistula arm gets its own rule in Abdominal, Gastrointestinal, and Renal Emergencies.