Applying hospital evidence to paramedicine: issues of indirectness, validity and knowledge translation.

The practice of emergency medicine (EM) has been intertwined with emergency medical services (EMS) for more than 40 years. In this commentary, we explore the practice of translating hospital based evidence into the prehospital setting. We will challenge both EMS and EM dogma-bringing hospital care to patients in the field is not always better. In providing examples of therapies championed in hospitals that have failed to translate into the field, we will discuss the unique prehospital environment, and why evidence from the hospital setting cannot necessarily be translated to the prehospital field. Paramedicine is maturing so that the capability now exists to conduct practice-specific research that can inform best practices. Before translation from the hospital environment is implemented, evidence must be evaluated by people with expertise in three domains: critical appraisal, EM, and EMS. Scientific evidence should be assessed for: quality and bias; directness, generalizability, and validity to the EMS population; effect size and anticipated benefit from prehospital application; feasibility (including economic evaluation, human resource availability in the mobile environment); and patient and provider safety.