Total Mission Time and Mortality in a Regional Interhospital Critical Care Transport System : A Retrospective Observational Study

Objective: We assessed the mortality risk related to the time for intensive care unit transport in a geographically large regional health care system. Methods: Patient-level data from critical care ambulance missions were analyzed for 2,067 cases, mission time, and relevant patient factors. Mission time was used as a surrogate for the “distance” to tertiary care, and mortality at 7 days and other intervals was assessed. Results: No increased mortality risk was found at 7 days in an unadjusted regression analysis (odds ratio = 1.00; range, 0.999-1.002; P = .66). In a secondary analysis, an increased mortality risk was observed in longer mission time subgroups and at later mortality assessment intervals (> 375 mission minutes and 90-day mortality; adjusted hazard ratio = 1.56; range, 1.07-2.28; P = .02). Negative changes in oxygenation and hemodynamic status and transport-related adverse events were associated with the longest flight times. Measurable but small changes during flight were noted for mean arterial pressure and oxygenation. Conclusion: The main finding was that there was no overall difference in mortality risk based on mission time. We conclude that transport distances or accessibility to critical care in the tertiary care center in a geographically large but sparsely populated region is not clearly associated with mortality risk