13.1 IV and Intraosseous Access
Key Takeaways
- In cardiac arrest and critical illness, obtain rapid IV or IO access for drugs and fluids—choose the route that can be established most quickly with available expertise.
- IO access is rapid, safe, and effective in infants and children when peripheral IV placement is delayed.
- Prefer IV/IO over the endotracheal route for resuscitation medications; ET delivery is a last resort with less reliable absorption.
- Common emergency IO sites include the proximal tibia (most taught), distal tibia, and proximal humerus when age-appropriate and trained.
- Flush after each medication; never delay high-quality CPR for prolonged IV attempts in a pulseless child.
Why Access Is a Core PALS Skill—Not a Side Task
Pediatric advanced life support algorithms assume you can deliver weight-based medications and volume into the central circulation. High-quality CPR generates limited cardiac output; drugs only help if they actually reach the heart and arteries. On the written exam and megacode, access questions test three linked ideas:
- Speed and reliability beat cosmetic preference for a perfect peripheral IV.
- IV and IO are both acceptable emergency routes; choose based on availability, expertise, and time to success.
- Access never replaces airway support, oxygenation, ventilation, or compressions—and it must not create long hands-off intervals.
Arrest and peri-arrest priorities
| Clinical state | Access expectation |
|---|---|
| Cardiac arrest | Establish IV or IO as soon as feasible during CPR; do not stop compressions for long IV hunts |
| Shock with poor perfusion | Rapid IV/IO so fluid and vasoactive drugs can start without delay |
| Unstable arrhythmia needing meds | Secure working access (preferably proximal) before or while preparing adenosine/antiarrhythmics |
| Stable child with time | Thoughtful peripheral IV with fewer attempts is appropriate |
In arrest, epinephrine timing (Chapter 8) and fluid or antiarrhythmic delivery depend on a working line. A team that spends four minutes on failed hand IVs while the child remains pulseless is off-algorithm—even if everyone "prefers IV."
Decision rule you can recite
Select the vascular access method that can be obtained most rapidly and reliably given the provider’s skill and equipment—then use it. Prefer IV or IO over endotracheal drug administration.
If a skilled provider can place a large-bore peripheral IV in seconds, use it. If peripheral veins are collapsed, burned, or repeatedly missed, go IO immediately. Many high-performance teams assign one role to access so CPR and defibrillation are never paused for needle shopping.
Intraosseous Access: Rapid, Safe, Effective
Intraosseous (IO) cannulation places a rigid needle into the marrow cavity of a long bone. The medullary space connects to the systemic venous circulation, so fluids and nearly all resuscitation drugs given IO behave like intravenous doses for emergency purposes. PALS and pediatric emergency science treat IO as a standard emergency route, not an exotic last resort after every possible IV fails.
Why IO shines in pediatrics
- Speed: Trained providers often achieve IO access in under a minute.
- Reliability in shock/arrest: Peripheral veins may vanish with vasoconstriction; bone marrow does not "collapse" the same way.
- Broad drug and fluid compatibility: Epinephrine, amiodarone, lidocaine, adenosine (with attention to flush technique), crystalloid, blood products (per protocol), and many other agents can be given IO.
- Age range: Manual and powered devices exist for infants through adolescents (and adults).
Common emergency IO sites (exam-level)
| Site | Teaching notes |
|---|---|
| Proximal tibia | Most commonly taught first-line pediatric emergency site; flat anteromedial surface distal to the tibial tubercle/growth-plate landmarks per device training |
| Distal tibia | Alternative when proximal tibia is injured, burned, or previously used |
| Proximal humerus | Useful alternative when lower extremities are unavailable; requires age-appropriate landmark skill |
| Distal femur | Used in some infant protocols when trained; know that local systems may teach it |
Do not place an IO into a fractured bone, a site of infection (cellulitis/osteomyelitis concern), or through a limb with a proximal vascular injury that would prevent drainage to the central circulation. If one site fails or extravasates, choose a different bone.
Technique principles (not a full skills checklist)
- Identify landmarks; stabilize the limb.
- Insert perpendicular to the bone surface with firm pressure until a loss-of-resistance / depth stop indicates marrow entry (device-specific).
- Confirm position: needle stands firmly, aspirate marrow/blood when possible (absence of aspirate does not always mean failure), and flush easily without soft-tissue swelling.
- Secure the needle; protect the site during CPR and transport.
- Infuse under pressure when needed—marrow resistance is higher than a free-flowing vein.
Complications to recognize
Extravasation into soft tissue (compartment syndrome risk), growth-plate injury if landmarks are wrong, infection (rare with short emergency use), fat or bone-marrow embolization (uncommon), and fracture. Continuous site inspection after every push prevents silent infiltration of vasoactive drugs.
IV Access Nuances, Flush Technique, and Why ET Is Last
Peripheral IV in resuscitation
When veins are visible and the provider is skilled, a well-functioning peripheral IV is excellent. Prefer larger, more proximal veins when giving ultrashort-acting drugs such as adenosine. During CPR, veins may be hard to find; limit attempts and escalate to IO. Central venous catheters provide durable multi-lumen access for ICU care but are not the first procedure during active pediatric arrest when IO can deliver drugs faster.
Flush after every medication
Resuscitation drugs given through an IV or IO must be followed by a saline flush large enough to clear the line and propel the drug into central circulation—especially important with IO (higher resistance) and with peripheral IVs far from the heart. Typical team practice:
- Announce the drug and dose (closed-loop).
- Push the drug.
- Immediately flush.
- Continue CPR; note the time for the next interval (e.g., epinephrine every 3–5 minutes).
Without a flush, a calculated perfect milligram dose may sit in the tubing or marrow needle dead space.
Prefer IV/IO over endotracheal administration
Some resuscitation drugs historically had endotracheal (ET) dosing tables. Absorption from the lung during arrest is unpredictable because pulmonary blood flow is low and distribution is uneven. Current PALS teaching prioritizes getting IV or IO access rather than planning an ET pharmacology strategy. If IV/IO truly cannot be obtained, follow current provider materials and medical direction for any residual ET option—but exam correct answers almost always choose establish IV/IO over "give the drug down the tube first."
Do not delay CPR for difficult IV
This rule is absolute in pulseless arrest:
- Compressions start within 10 seconds of recognizing arrest (Chapter 8).
- Access is obtained during CPR by a second provider when possible.
- Failed IV attempts must not produce prolonged pauses or abandoned compressions.
- IO is the tool that makes this rule practical.
Clinical scenarios
Scenario A — Arrest, no line: A 12 kg toddler is pulseless in PEA. CPR is excellent. After two failed peripheral IV attempts in under a minute, the access provider places a proximal tibial IO, flushes, and the team gives epinephrine 0.01 mg/kg IO without stopping compressions. Correct prioritization.
Scenario B — Shock, delayed IV: A 4-year-old with hypovolemic shock has no IV after several minutes in the field. IO is placed; 20 mL/kg isotonic crystalloid is pushed with reassessment (Chapter 5). Waiting for a pediatric center IV specialist while the child remains hypotensive is wrong.
Scenario C — ET temptation: The team has an ETT and no vascular access yet. The correct next access move is still IO/IV during CPR, not defaulting to ET epinephrine as the primary plan.
Bottom line for 13.1: In arrest and critical illness, obtain rapid IV or IO based on speed and skill; treat IO as standard, effective emergency access; use common sites such as the proximal tibia; flush after meds; prefer IV/IO over ET; and never sacrifice CPR quality for a difficult IV.
During pediatric cardiac arrest, which vascular-access principle best matches PALS teaching?
Why is intraosseous access emphasized for critically ill infants and children when peripheral IV placement is delayed?
After giving epinephrine through a newly placed tibial IO during CPR, what immediate step improves drug delivery to the central circulation?