5.5 IV/IO Access and Medication Safety

Vascular Access in the Code

Drugs cannot help unless they reach the central circulation, so vascular access is a core resuscitation skill. During arrest, the team establishes IV or IO access while compressions continue — you do NOT stop CPR for a routine access attempt. A large peripheral IV (antecubital or larger) is the first choice; push the drug, then follow with a 20 mL saline flush and elevate the limb to speed central delivery during low-flow CPR.

When a peripheral IV cannot be obtained quickly, intraosseous (IO) access is the preferred alternative. An IO needle is placed into the marrow cavity of the proximal tibia, proximal humerus (humeral head), or distal femur in adults; the marrow is a non-collapsible venous plexus that drains into the central circulation. IO delivers drugs and fluids at rates and systemic concentrations comparable to central venous access, and every ACLS drug — epinephrine, amiodarone, lidocaine, adenosine, calcium, sodium bicarbonate, and crystalloid — can be given IO.

Access route priority

The endotracheal route is no longer recommended because absorption through the tracheobronchial tree is unpredictable and serum levels are erratic. It is a fallback only when IV and IO are both impossible, and only a few lipid-soluble drugs (the "NAVEL" set — naloxone, atropine, vasopressin, epinephrine, lidocaine) can be given that way, at higher doses.

IO contraindications and pitfalls

Avoid placing an IO in a bone that is fractured, has had a prior IO attempt in the last 24-48 hours (the previous hole leaks), is infected/cellulitic at the site, or has hardware such as a prosthetic joint. After insertion, confirm placement (the needle stands upright without support and you can aspirate marrow), then flush briskly to open the marrow space before infusing — IO infusions can be painful in conscious patients, so a small dose of lidocaine into the IO space is often used for awake patients.

These details matter clinically and occasionally appear as distractors that try to get you to place an IO in a fractured or infected limb.

Closed-Loop Communication and Dose Tracking

The most preventable code errors are communication and dosing errors, so the resuscitation team uses closed-loop communication for every order. A complete medication order names the drug, dose, route, and timing, the receiver repeats it back verbatim, and then announces when it has been given.

Closed-loop example

1. Leader: "Give epinephrine 1 milligram IV now, and tell me when it's in."
2. Nurse: "Epinephrine 1 milligram IV — giving it now."
3. Nurse (after administering): "Epinephrine 1 milligram IV is in, time 14:22."
4. Leader: "Thank you — next epi due in 3 to 5 minutes."

This loop prevents the two classic failures: a drug never given because no one confirmed, and a drug double-given because two people each thought they heard the order. The timekeeper/recorder logs every dose and the clock, which is how the team keeps epinephrine on its 3-5 minute cadence and avoids exceeding ceilings like atropine 3 mg or stacking antiarrhythmics.

Medication-safety checklist

• Right rhythm pathway — does the drug match this patient's pulse status and rhythm?
• Right dose and route — confirm against the algorithm, not habit.
• Right timing — has the minimum interval elapsed (e.g., epinephrine q3-5 min)?
• Running total — track cumulative atropine, lidocaine (max ~3 mg/kg), and antiarrhythmic doses.
• Compatibility — avoid combining a second antiarrhythmic without expert consultation.

Keeping CPR Quality While Managing Drugs

Access and pharmacology must never degrade chest-compression fraction. The leader's discipline is to keep hands on the chest while access and drugs happen in parallel. Practical rules:

• Do not pause compressions for IV/IO attempts; assign access to a dedicated team member.
• Pre-draw and label anticipated drugs (epinephrine, amiodarone) so administration is instant at the next rhythm check.
• Give drugs during compressions, not during the brief rhythm/pulse check, so the medication circulates.
• Announce the next dose's due time right after giving one, so the timekeeper can prompt it.

Common traps

• Launching multiple simultaneous IV attempts while no one is compressing.
• Losing track of when epinephrine was last given, leading to early or late redosing.
• Choosing a drug because it is familiar rather than because the rhythm pathway calls for it.
• Defaulting to the endotracheal route when an IO could be placed in seconds.
• Treating drug administration as more urgent than defibrillation or compressions — electricity and CPR come first.

Scenario anchor: In VF arrest, the leader orders "epinephrine 1 mg IV now," the nurse repeats and confirms it is in, and the recorder logs the time so the next dose lands at the 3-5 minute mark — all while compressions never stop and a defibrillator stays charged for the next shock. That coordination, more than any single drug fact, is what the megacode tests.