Association between prehospital physician involvement and survival after out-of-hospital cardiac arrest: A Danish nationwide observational study

33 Systematic review of the effectiveness of prehospital critical care following out-of-hospital cardiac arrest

“…Of the six observational studies included, three studies demonstrated an association between prehospital critical care and improved outcomes after OHCA. [22][23][24] The other three studies did not demonstrate any difference in patientcentred outcomes after OHCA when comparing prehospital critical care with ALS. 17,20,21 We believe that the conflicting findings can be at least partially explained by study design and the logistics of prehospital care for OHCA.…”

“…29 In this review, in all publications that compare prehospital critical care with ALS in the same EMS, the critical care group had better prognostic factors. 17,[21][22][23][24] While all of these publications use statistical methods to adjust for this imbalance, there is a strong possibility that unmeasured residual confounding factors bias the results in favour of prehospital critical care.…”

“…17 In Hamilton et al's study from Denmark, 39.3% of cases attended by prehospital physicians occur within a metropolitan area, compared to 14.8% in the non-physician group. 23 Patients receiving prehospital critical care in these studies are therefore more likely to receive early coronary angiography, targeted temperature management and treatment in high volume centres, all of which have been linked to better outcomes. [30][31][32] Finally, the training, experience and governance structure of EMS providers needs to be considered when comparing prehospital critical care and ALS for OHCA.…”

“…33 Prehospital critical care providers will be highly experienced in the care of critically ill patients, including OHCA, through their practice in hospital or as a result of targeted dispatch to cases of severe illness or injury. 17,23 In addition, prehospital critical care providers often have the support of advanced clinical governance structures with regular case reviews and quality improvement projects, which might not be available to the cohort of ALS providers. 34 Finally, prehospital critical care providers potentially have more freedom to select destination hospitals, such as cardiac or trauma centres, as appropriate for each patient.…”

“…17 All of these aspects make it possible that prehospital providers can achieve better outcomes for an individual patient following OHCA. [22][23][24] …”