Abstract Body: Background: Patients requiring interfacility transfer (IFT) after out-of-hospital cardiac arrest (OHCA) are at risk for poor outcomes due to delays in care and other factors. Identifying differences between patients with and without IFT following OHCA may better inform systems of care.

Research Question: What differences exist among patients with and without IFT following OHCA?

Aims: Identify demographics, clinical characteristics, and outcomes that differ between patients transported to versus presenting directly to MaineHealth Maine Medical Center (MHMMC).

Methods: This IRB-approved study (#99884-25) compared OHCA patients with and without IFT after OHCA between 2017 and 2025. Univariate analysis included demographics, pre-existing comorbidities, OHCA variables (including witnessed, bystander CPR, time to CPR (TTCPR), time to return of spontaneous circulation (TTROSC), and etiology of OHCA), illness severity at hospital admission, targeted temperature control (TTC) parameters, and outcomes. Data are presented as median (IQR) and a p-value < 0.05 was significant.

Results: Of 636 OHCA patients screened, 352 (55.3%) required IFT and 284 (44.7%) did not. Demographic data, rates of witnessed arrest, bystander CPR, initial rhythm, TTROSC, and TTCPR were similar between groups, but patients without IFT more often had peripheral vascular disease (n=29 vs n=16, p<0.009). IFT patients had lower lactate (4.6 mmol/L [2.6, 7.8] vs 8.3 mmol/L [4.2, 12.0], p<0.001), blood glucose (199 mg/dL [144, 277] vs 256 mg/dL [180, 318], p<0.001), and better pH (7.26, [7.16, 7.32] vs 7.17 [7.04, 7.27], p<0.001) at admission. IFT patients had TTC initiated prior to admission more frequently (n=64 vs n=2, p<0.001), but had a longer time from OHCA to target temperature (513 min [355, 672], vs 340 min [217,480], p<0.001). Among patients with IFT, IFT duration was shorter among survivors to ICU discharge (4 hours [3, 6], vs 5 hours [4, 7], p=0.003). There were no differences in shock at admission, complications during ICU treatment, clinical outcomes, or functional outcomes at hospital discharge. The ICU survival rate after OHCA was 44% among patients with IFT and 43% among patients without IFT (p=0.918).

Conclusion: IFT patients had less severe laboratory abnormalities with no differences in clinical outcomes compared to those admitted directly. Further study is needed to investigate the effect of IFT on OHCA outcomes.