What is the comparison between Intravenous (IV) and Intraosseous (IO) access in terms of Return of Spontaneous Circulation (ROSC) and neurologic outcome in cardiac arrest?

From the Guidelines

In cardiac arrest, IV access is associated with better outcomes in terms of Return of Spontaneous Circulation (ROSC) and neurologic outcome compared to IO access, as evidenced by a recent consensus on cardiopulmonary resuscitation and emergency cardiovascular care science 1.

Key Findings

• The use of IO access is associated with worse outcomes, including lower rates of ROSC and survival to hospital discharge with a favorable neurological outcome, compared to IV access 1.
• The adjusted OR for ROSC with IO access compared to IV access is 0.72 (95% CI, 0.68–0.76), indicating a significant difference in outcomes between the two routes 1.
• The critical outcome of survival to hospital discharge with a favorable neurological outcome also favors IV access, with an adjusted OR of 0.60 (95% CI, 0.52–0.69) for IO access compared to IV access 1.

Recommendations

• IV access should be the preferred route for medication administration in cardiac arrest, with IO access considered only if IV access is difficult or impossible 1.
• If IO access is established, the same medications at identical doses should be administered as for IV access, including epinephrine, amiodarone, and lidocaine, with a 20mL fluid flush after medication administration to ensure drugs reach central circulation.

Rationale

• The physiological basis for the difference in outcomes between IV and IO access is not fully understood, but may be related to the slightly slower onset times of IO access, which can delay the administration of critical medications 1.
• Minimizing delays in medication administration is crucial in cardiac arrest, and the choice of access route should be guided by the need for rapid and reliable drug delivery 1.

From the Research

Comparison of IV and IO Access

• The comparison between Intravenous (IV) and Intraosseous (IO) access in terms of Return of Spontaneous Circulation (ROSC) and neurologic outcome in cardiac arrest has been studied in several research papers 2, 3, 4, 5, 6.
• A study published in the Air Medical Journal in 2019 found that higher ROSC rates were achieved with IV access versus IO access, with 45.1% of patients achieving ROSC with IV access compared to 25.7% with IO access 3.
• However, a prospective, parallel-group, cluster-randomised study published in Resuscitation in 2021 found that there was no significant difference in ROSC, survival to discharge, or survival with good neurological outcome between patients who received IV access only and those who received IV or IO access 5.
• Another study published in BMC Emergency Medicine in 2015 found that strong predictors for survival and favorable neurological outcome were ventricular tachycardia/ventricular fibrillation as initial rhythm, cardiac etiology, and time to ROSC < 20 minutes, but did not specifically compare IV and IO access 4.
• A protocol for a randomized clinical trial published in Resuscitation Plus in 2023 aims to determine whether there is a difference in patient outcomes depending on the type of vascular access attempted during out-of-hospital cardiac arrest, with a primary outcome of sustained return of spontaneous circulation and key secondary outcomes including survival and survival with a favorable neurological outcome at 30 days 6.

Neurologic Outcome

• A study published in the Singapore Medical Journal in 2017 found that targeted temperature management after ROSC confers neuroprotection and leads to improved neurological outcomes, and that interventions such as prompt identification and treatment of the cause of cardiac arrest, treatment of electrolyte abnormalities, and optimization of haemodynamic management via judicious intravenous fluids and vasoactive drugs can potentially lead to more patients being discharged from hospital alive with good neurological function 2.
• The study published in Resuscitation in 2021 found that there was no significant difference in survival with good neurological outcome between patients who received IV access only and those who received IV or IO access 5.
• The protocol for the randomized clinical trial published in Resuscitation Plus in 2023 includes survival with a favorable neurological outcome at 30 days as a key secondary outcome 6.