RCT: No Significant Difference Between Intraosseous and Intravenous Vascular Access in Out-of-Hospital Cardiac Arrest Outcomes

Background: Out-of-hospital cardiac arrest (OHCA) is a major global health concern, resulting in high mortality rates despite advancements in emergency care. In Denmark alone, approximately 5,000 cases occur annually, with a 30-day survival rate of only about 14%. Rapid vascular access during cardiopulmonary resuscitation (CPR) is crucial for administering medications like epinephrine, as recommended by international guidelines. Both intraosseous (IO) and intravenous (IV) routes are routinely used, but their comparative effectiveness remains unclear. Current guidelines favor IV access for initial attempts, yet this recommendation is based on very low-certainty evidence, highlighting the need for well-designed clinical trials.

Objective: To compare the effectiveness of initial intraosseous versus intravenous vascular access on sustained return of spontaneous circulation (ROSC) in adults experiencing nontraumatic OHCA.

Methods: This randomized, parallel-group superiority trial was conducted across all five regions of Denmark, covering 5.9 million inhabitants. Adults aged 18 years or older with nontraumatic OHCA requiring vascular access during CPR were randomized to receive either initial IO or IV access. The IO group was further randomized to humeral or tibial access for a secondary comparison. The primary outcome was sustained ROSC, defined as no need for chest compressions for at least 20 minutes. Key secondary outcomes included 30-day survival and survival with favorable neurologic outcome (modified Rankin scale score of 0–3). Procedural outcomes such as success rates of vascular access within two attempts, time to successful access, and time to first epinephrine administration were also assessed.

Results: Among 1,479 patients included in the primary analysis (731 in the IO group and 748 in the IV group), successful vascular access within two attempts was achieved in 92% of the IO group versus 80% of the IV group. Despite the higher success rate with IO access, the time to first successful access and time to first epinephrine dose were similar between groups. Sustained ROSC occurred in 30% of patients in the IO group and 29% in the IV group (risk ratio [RR], 1.06; 95% confidence interval [CI], 0.90–1.24; P=0.49). At 30 days, survival rates were 12% in the IO group and 10% in the IV group (RR, 1.16; 95% CI, 0.87–1.56), with favorable neurologic outcomes observed in 9% and 8% of patients, respectively (RR, 1.16; 95% CI, 0.83–1.62). No significant differences were found in procedural times, adverse events, or quality-of-life measures among survivors.

Conclusions: In adults with nontraumatic OHCA, initial intraosseous vascular access did not result in a significant difference in sustained ROSC compared to intravenous access. Both methods yielded comparable survival rates and neurologic outcomes at 30 days, suggesting that the choice of vascular access route may not critically impact immediate resuscitation success.

Implications for Practice: These findings indicate that emergency medical services can opt for either intraosseous or intravenous vascular access during resuscitation based on provider expertise, patient anatomy, and situational considerations without adversely affecting patient outcomes. Emphasizing flexibility in vascular access approach may facilitate quicker access and streamline resuscitation efforts in the prehospital setting.

Study Strengths and Limitations: Strengths include the randomized design, large sample size, and nationwide implementation, enhancing generalizability. Limitations involve potential crossover between groups, lack of blinding among clinicians, and the study being underpowered to detect small differences in long-term outcomes.

Future Research: Further studies are needed to assess long-term survival and neurologic outcomes, and to explore whether specific patient subgroups may benefit more from one vascular access method over the other during cardiac arrest resuscitation.

Reference: Vallentin MF, Granfeldt A, Klitgaard TL, et al. Intraosseous or Intravenous Vascular Access for Out-of-Hospital Cardiac Arrest. New England Journal of Medicine. 2024 Oct 31; DOI: http://doi.org/10.1056/NEJMoa2407616