Is intravenous (IV) access preferred over intraosseous (IO) access in prehospital settings for a general patient population, including adults and children?

IV Access is Preferred Over IO Access in Prehospital Settings

For prehospital vascular access, attempt intravenous (IV) access first, as it is associated with better survival and neurological outcomes compared to intraosseous (IO) access, though IO should be used immediately if IV access is unsuccessful or not feasible. 1

Primary Recommendation

The 2020 International Consensus on Cardiopulmonary Resuscitation provides clear guidance that IV access should be the first-line approach for drug administration during adult cardiac arrest, with IO access reserved as a backup when IV access fails or cannot be obtained 1. This recommendation applies to both out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) settings 1.

Evidence Supporting IV Preference

Mortality and Survival Outcomes

The evidence demonstrates clinically significant differences favoring IV access across critical outcomes 1:

• Survival to hospital discharge: IO access is associated with 20 fewer survivors per 1,000 cardiac arrests compared to IV access (adjusted OR 0.71,95% CI 0.63-0.79) 1

• Survival with favorable neurological outcome: IO access is associated with 19 fewer survivors with good neurological outcomes per 1,000 cardiac arrests (adjusted OR 0.60,95% CI 0.52-0.69) 1

• Return of spontaneous circulation (ROSC): IO access is associated with 61 fewer patients achieving ROSC per 1,000 cardiac arrests (adjusted OR 0.72,95% CI 0.68-0.76) 1

These findings are based on 4 observational studies including over 70,000 adult OHCA patients 1.

Important Caveats and Clinical Context

Evidence Quality Limitations

The certainty of evidence is very low due to risk of bias and inconsistency in observational studies 1. A critical confounder is that patients requiring IO access may inherently be more critically ill or have more difficult vascular access, making direct comparison challenging 1. The guideline task force acknowledged that patients who received IO access may have had worse baseline characteristics that contributed to poorer outcomes 1.

When IO Access Becomes Preferred

IO access should be used immediately without delay if 1:

• Initial IV access attempts are unsuccessful
• IV access is not feasible due to patient factors (severe hypovolemia, shock, obesity, IV drug use)
• Time constraints make IV access impractical

In trauma resuscitation specifically, IO access demonstrates higher first-attempt success rates (46% higher relative risk) and significantly shorter procedure times (5.67 minutes faster on average) compared to IV access 2. For hypotensive trauma patients in severe shock, IO access may be the superior initial choice 2.

Practical Procedure Time Considerations

While the mortality data favors IV access, procedure efficiency data shows conflicting patterns 3, 2, 4:

• IO access requires less time to establish: Mean procedure time of 2.3 minutes for IO versus 9.9 minutes for central venous catheterization 3
• IO has higher first-attempt success rates in emergency settings: 90% for IO versus 60% for central venous access 3
• Time savings are amplified in difficult conditions: IO access saves 20 seconds under normal conditions and 39 seconds when wearing CBRN protective equipment 4

Clinical Algorithm for Prehospital Vascular Access

1. Attempt peripheral IV access first in all patients requiring vascular access during resuscitation 1

2. Switch to IO access immediately if:

   • Peripheral IV cannot be obtained within 1-2 attempts
   • Patient is in profound shock making IV access unlikely to succeed
   • Resuscitation urgency requires immediate vascular access 1

3. Consider IO as first-line for:

   • Severe trauma patients with hemorrhagic shock 2
   • Patients requiring multiple simultaneous life-saving interventions 5
   • Mass casualty or austere environments where time is critical 4

4. Preferred IO sites: Tibial insertion is most commonly documented, though humeral sites may also be used 1. No evidence exists to recommend one IO site over another 1.

Common Pitfalls to Avoid

• Do not delay resuscitation attempting multiple IV access attempts: If initial IV attempts fail, transition to IO access rather than persisting with IV attempts that delay drug administration 1, 3

• Do not assume IO and IV are equivalent: The observational data consistently shows worse outcomes with IO access, even if causality is uncertain 1

• Do not withhold analgesia in IO patients: Evidence suggests lower rates of analgesic administration in patients with IO access, which may represent a quality gap in care 5

• Recognize that IO access indicates higher acuity: Patients receiving IO access have higher injury severity scores and mortality rates, requiring more aggressive overall resuscitation 6, 5