Conceptual Overview

Obtaining vascular access in a critically ill or injured child is one of the most challenging procedural skills in emergency medicine. Pediatric veins are smaller, deeper, and surrounded by more subcutaneous fat than adult veins. Dehydrated, hypothermic, or shocked children have even less visible vasculature.

The key principle: don't delay resuscitation for IV access. If peripheral IV cannot be obtained within 90 seconds or 2 attempts, move directly to intraosseous (IO) access. IO access is fast, reliable, and can deliver any medication, fluid, or blood product that an IV can deliver.

PALS guidance: In cardiac arrest, the IO should be the first-line access — not something you try after failing IV. Every minute without access is a minute without epinephrine. Go IO early and go IO often.
Peripheral IV Access

Preferred Sites by Age

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Age Group Primary Sites Catheter Size Tips
Neonate (0-28 days) Dorsal hand, dorsal foot, scalp veins, antecubital 24G Scalp veins lack valves; use transilluminator
Infant (1-12 months) Dorsal hand, antecubital, saphenous, scalp 24G-22G Saphenous is anterior to medial malleolus — very reliable
Toddler/preschool (1-5 yr) Dorsal hand, antecubital, saphenous, forearm 22G-20G Consider topical anesthetic (LMX/EMLA) if not emergent
School age (6-12 yr) Antecubital, forearm, dorsal hand 22G-20G Approaching adult-like access; AC preferred for resuscitation
Adolescent (13+ yr) Same as adult: AC, forearm, hand, EJ 20G-18G Adult-sized veins; can use standard adult technique
The saphenous vein is your secret weapon: The greater saphenous vein is located 1 cm anterior and superior to the medial malleolus. It's reliably located even when you can't see it, and it's accessible even in chubby infants. When hands and AC fail, go to the ankle. Palpate the medial malleolus, move 1 cm anterior, insert at 15-30° angle.

Technique Tips for Difficult Access

  • Transillumination: Place a bright light underneath the extremity to illuminate veins — particularly useful in infants and neonates
  • Warm compresses: Vasodilate superficial veins (2-3 minutes of warm towel application)
  • Ultrasound guidance: For deeper veins (brachial, basilic) when surface veins are not visible; increasingly standard in pediatric EDs
  • Tourniquet technique: Use a rubber band or small tourniquet; in neonates, an assistant's finger wrapped around the extremity works as a tourniquet
  • Gravity: Lower the extremity below the heart level to engorge veins
Intraosseous (IO) Access

IO access is the most important procedural skill for pediatric resuscitation. It provides access to the non-collapsible venous plexus within bone marrow. Flow rates are excellent, and anything you can give IV can be given IO — including fluids, vasopressors, blood products, antibiotics, and sedating agents.

IO Sites

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Site Landmark Age Preference Notes
Proximal tibia (primary) 1 cm below tibial tuberosity, medial flat surface All ages (first choice) Flat surface, easy landmark; avoid growth plate — insert slightly medial and distal to tuberosity
Distal tibia 1-2 cm above medial malleolus, midline on flat surface All ages (alternative) Thinner cortex; less soft tissue overlay; good alternative when proximal site compromised
Distal femur 1-2 cm above lateral condyle, midline of anterior surface All ages (alternative) More soft tissue; slightly harder to stabilize; avoid in femur fractures
Proximal humerus Greater tubercle, arm internally rotated Older children/adolescents Higher flow rates; used with powered IO (EZ-IO); less common in small children

IO Insertion Technique

  1. Identify landmarks: Palpate tibial tuberosity. Mark insertion site 1 cm below and slightly medial.
  2. Stabilize the leg: Place a rolled towel behind the knee. Do NOT place your hand behind the leg — the needle can pass through thin infant bone.
  3. Prep the site: Chlorhexidine or betadine if time permits.
  4. Insert the needle: Aim 90° to the bone surface (or slightly caudal to avoid growth plate). If using manual needle, use a twisting motion with steady pressure. If using EZ-IO, engage the drill and advance until loss of resistance ("give").
  5. Confirm placement:
    • Needle stands upright without support
    • Aspiration of marrow (in ~60% of cases)
    • Flush without subcutaneous infiltration
    • Easy infusion of fluids
  6. Flush and infuse: Connect to standard IV tubing. For flow, use pressure bag (300 mmHg) or syringe push technique.
IO pain management: IO infusion in a conscious patient is painful. Before any fluid or medication push, slowly administer lidocaine 2% (preservative-free) 0.5 mg/kg IO (max 20 mg). Allow 60 seconds to take effect. Then flush with 2-5 mL NS. Forgetting this causes significant distress — the child will scream during every push. Don't forget the lidocaine.

IO Needle Sizing

Device Size Patient Weight
EZ-IO Pink 15mm needle 3-39 kg
EZ-IO Blue 25mm needle ≥ 40 kg
Manual IO (Cook, Jamshidi) 16-18 gauge Any (technique-dependent)

IO Contraindications

  • Fracture of the target bone (fluid will extravasate through the fracture site)
  • Previous IO attempt in the same bone within 24-48 hours
  • Overlying infection or burn at insertion site
  • Osteogenesis imperfecta or severe osteopetrosis
  • Prosthetic limb or prior surgical hardware at the site
IO is not just a backup plan: In pediatric cardiac arrest, AHA recommends IO as equivalent to IV access. Many experienced pediatric providers go straight to IO in any critically ill child under 6 years old because it's faster and more reliable than hunting for peripheral veins in a sick, vasoconstricted child. First-attempt IO success rate is >90%. First-attempt IV success rate in critically ill children is <50%. The math speaks for itself.
Umbilical Venous Catheter (UVC)

In neonates (first 7-14 days of life), the umbilical vein provides rapid, reliable vascular access. The umbilical stump contains two arteries (small, thick-walled) and one vein (large, thin-walled, usually at the 12 o'clock position).

Insertion Technique

  1. Cut the cord: Trim the umbilical stump to 1-2 cm above the skin using a scalpel. Control bleeding with umbilical tape tied loosely around the base.
  2. Identify the vein: The umbilical vein is the single large, thin-walled vessel (usually at 12 o'clock). The two arteries are smaller with thicker walls.
  3. Insert the catheter: Pre-flush a 3.5 or 5 Fr umbilical catheter with saline. Gently insert into the vein, angling toward the right shoulder. Advance 2-4 cm until blood return is obtained.
  4. Confirm position: Aspirate blood freely. If resistance is met (likely in a false passage or the liver), withdraw slightly and redirect.
  5. Secure: Suture or tape in place. Confirm position radiographically (tip should be at the IVC-RA junction).

Depth of Insertion

UVC depth formula: Insertion depth (cm) = (Birth weight in kg × 1.5) + 5.5 cm
Alternatively: Insert until free blood return, typically 2-5 cm in term neonates.
Emergency depth: Insert just until blood return (usually 2-4 cm) — do not advance deep without radiographic confirmation.
Do NOT advance a UVC against resistance: Forced advancement can create a false track into the liver parenchyma, causing hemorrhage or hepatic laceration. In an emergency, you only need the catheter tip just inside the vein — enough for drug delivery. Deep placement (for TPN/prolonged use) requires radiographic confirmation.
Central Venous Access

Central venous catheterization in children uses the same anatomic principles as in adults, but with smaller structures and higher risk of complications. Ultrasound guidance is strongly recommended for all pediatric central line placements.

Site Comparison

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Site Advantages Disadvantages Catheter Size
Femoral vein Easiest landmark, compressible, no pneumothorax risk Higher infection rate, impedes CPR leg positioning 4-5 Fr (<10 kg), 5-7 Fr (>10 kg)
Internal jugular US-guided: high success rate, reliable anatomy Pneumothorax risk (low with US), difficult with cervical collar 4-5 Fr (<10 kg), 5-7 Fr (>10 kg)
Subclavian Lowest infection rate, comfortable for patient Highest pneumothorax risk, not compressible, technically difficult in small children 4-5 Fr (<10 kg), 5-7 Fr (>10 kg)
Femoral is the typical emergency choice: In a pediatric emergency, the femoral vein is usually the go-to site for central access. It has easy landmarks (medial to the femoral artery pulse, below the inguinal ligament), no pneumothorax risk, and doesn't require Trendelenburg positioning. The infection rate is manageable when the line is placed with sterile technique and removed as soon as possible.
Quick Reference

Access Algorithm

  1. Attempt peripheral IV — 2 attempts or 90 seconds max
  2. Go to IO — proximal tibia first choice; EZ-IO pink for <39kg, blue for ≥40kg
  3. Consider central line — femoral preferred in emergencies
  4. Neonates: Consider UVC in first 7-14 days of life

IO Insertion Checklist

  • Site: 1 cm below and medial to tibial tuberosity
  • Angle: 90° to bone (slightly caudal to avoid growth plate)
  • Confirm: Needle stands alone, aspirate marrow, flush without infiltration
  • If conscious: Lidocaine 0.5 mg/kg IO before medications
  • Use pressure bag or syringe push for adequate flow rate

PIV Catheter Sizing

  • Neonate: 24G
  • Infant: 24-22G
  • Toddler/preschool: 22-20G
  • School age: 22-20G
  • Adolescent: 20-18G
Clinical Pearls
The 90-second rule: In a critically ill or arresting child, you have 90 seconds to establish peripheral IV access before moving to IO. This isn't arbitrary — it's based on data showing that delayed epinephrine in pediatric cardiac arrest worsens outcomes. Every minute without access is a minute without life-saving medications. Don't waste time on a third or fourth IV attempt.
IO flow rates can be improved: Gravity alone produces ~10-15 mL/min through an IO. This is inadequate for resuscitation. Use a pressure bag at 300 mmHg (increases to ~40-80 mL/min) or the syringe push-pull technique (fastest method — a 60 mL syringe with stopcock can push 60 mL in seconds). For boluses, always use active pressure.
External jugular (EJ) vein - the overlooked option: The EJ is a large, superficial vein that runs from the angle of the mandible to the mid-clavicle. In children, it's often visible with Trendelenburg positioning and can accommodate a 20-22G catheter. It's peripheral access (not central), but it's fast and provides good flow. Place the child head-down, turn the head away, and the EJ typically pops up.
Compartment syndrome from IO: IO-related compartment syndrome is rare but devastating. It occurs when the needle perforates through the posterior cortex or when fluid extravasates through a fracture or previous IO site. Monitor the calf circumference during IO infusion. If the leg begins to swell, the IO is mispositioned or has dislodged. Remove it, apply pressure, and establish access at a different site (different bone).
References
  1. Ralston M, Hazinski MF, et al. Pediatric Advanced Life Support (PALS) Provider Manual. American Heart Association; 2020.
  2. Tobias JD, Ross AK. Intraosseous infusions: a review for the anesthesiologist with a focus on pediatric use. Anesth Analg. 2010;110(2):391-401.
  3. Neuhaus D, Weiss M, Engelhardt T, et al. Semi-elective intraosseous infusion after failed intravenous access in pediatric anesthesia. Paediatr Anaesth. 2010;20(2):168-171.
  4. de Caen AR, Berg MD, Chameides L, et al. Part 12: Pediatric Advanced Life Support: 2015 AHA Guidelines Update. Circulation. 2015;132(18 Suppl 2):S526-S542.
  5. Tintinalli JE, Stapczynski JS, Ma OJ, et al. Tintinalli's Emergency Medicine. 9th ed. McGraw-Hill; 2020.
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