Conflict of Interest Declaration
The ILCOR Continuous Evidence Evaluation process is guided by a rigorous ILCOR Conflict of Interest policy. The following Task Force members and other authors were recused from the discussion as they declared a conflict of interest: none applicable.
The following Task Force members and other authors declared an intellectual conflict of interest and this was acknowledged and managed by the Task Force Chairs and Conflict of Interest committees: Janet Bray and Judith Finn.
Bray J, Finn J, Lockey A, Bhanji F, Bigham B, Duff J, Gilfoyle E Pellegrino J, Monsieurs K, Breckwoldt J, Hsieh M, Iwami T, Okamoto D, Ma M, Yeung J, Greif R on behalf of the EIT Task Forces.
Collaborators: Ziad Nehme, Andrew Nguyen
Emergency Medical Services (EMS) Experience and Exposure to OHCA resuscitation in Adults and Children Consensus on Science with Treatment Recommendations [Internet] Brussels, Belgium: International Liaison Committee on Resuscitation (ILCOR) Education, Implementation and Teams Task Force, 2019 December 24. Available from: http://ilcor.org
Systematic Review: Bray J, Nehme Z, Nguyen A, Lockey A, Finn J, A systematic review of the impact of emergency medical service practitioner experience and exposure to out of hospital cardiac arrest on patient outcomes, Resuscitation (2020), doi:https://doi.org/10.1016/j.resuscitation.2020.07.025
The continuous evidence evaluation process for the production of Consensus on Science with Treatment Recommendations (CoSTR) started with a systematic review (Bray, 2019, PROSPERO -CRD42019153599) conducted by an expert systematic review team with the involvement of clinical content experts. Evidence for adult and pediatric literature was sought and considered by the Education, Implementation and Teams (EIT) Task Force. These data were taken into account when formulating the Treatment Recommendations.
All types of EMS that perform resuscitations were included (Emergency Medical Technicians, Paramedics -Basic and Advanced Life Support, Prehospital physicians). All published definitions of EMS practitioners experience or exposure were accepted.
We identified two main types of comparisons in the literature. The first type examined the exposure and years of career experience of the team performing resuscitation, and the second type examined the exposure and years of career experience of individuals within the team (e.g. team leader or treating paramedic).
There was high heterogeneity among studies. We were unable to perform a meta-analysis, and have conducted a narrative synthesis of the findings. This synthesis is structured around each outcome and reported separately for exposure and experience.
The PICOST (Population, Intervention, Comparator, Outcome, Study Designs and Timeframe)
Population: Adults and children who are in cardiac arrest in the out-of-hospital setting (P).
Intervention: Resuscitation by experienced emergency medical service practitioners or practitioners with higher exposure to resuscitation.
Comparators: Resuscitation by less experienced or lower exposed practitioners.
Outcomes: Survival to hospital discharge/30-days with good neurological outcome, survival to hospital discharge/30-days, survival to hospital (event survival) and prehospital return of spontaneous circulation (ROSC) were ranked as critical outcomes.
Study Designs: Randomized controlled trials (RCTs) and non-randomized studies (non-randomized controlled trials, interrupted time series, controlled before-and-after studies, cohort studies) were eligible for inclusion. All original research articles (both prospective and retrospective) were included with no language restrictions. Unpublished studies (e.g., conference abstracts, trial protocols) were excluded.
Timeframe: All years and all languages were included as long as there was an English abstract. Literature search updated to October 14, 2019.
PROSPERO Registration CRD42019153599
Consensus on Science
Seven studies were included in the narrative synthesis (Bjornsson 2011 64; Dyson 2016 154; Gold 2009 341; Lukic 2016 591; Soo 999 535; Tuttle 2018 654; Weiss 2018 332). The overall quality of evidence was rated as very low for all outcomes primarily due to a very serious risk of bias. The individual studies were all at a critical risk of bias due to confounding. Because of this, and a high degree of heterogeneity, no meta-analyses could be performed.
Studies examining exposure to resuscitation
For the critical outcome of survival with favourable neurologic outcome at discharge/30 days we identified very low quality of evidence (downgraded for risk of bias and imprecision) from one non-RCT (Weiss 2018 332). This study examined exposure for EMS-physicians, and reported unadjusted data with insufficient numbers of events to be confident in the direction of the outcome estimates.
For the critical outcome of survival to discharge/30 days we identified very low quality of evidence (downgraded for risk of bias and imprecision) from three non-RCTs (Bjornsson 2011 64; Dyson 2016 154; Weiss 2018 332). The largest and highest quality non-RCT (Dyson 2016 154) reported adjusted outcomes and examined the whole resuscitating teams’ exposure in the preceding three years. This study found higher team exposure in the preceding three years was associated with increased survival to discharge: compared to ≤6 exposure reference group, >6-11 exposures (AOR 1.26, 95% CI 1.04–1.54), 11 to 17 exposures (AOR 1.29, 95% CI 1.04–1.59), >17 exposures (AOR 1.50, 95% CI 1.22–1.86).
The remaining two non-RCTs (Bjornsson 2011 64; Weiss 2018 332) reported unadjusted outcomes and used the averaged exposure of team leaders to resuscitation over one (Weiss 2018 332) and three year study periods (Bjornsson 2011 64). These studies found no association between exposure to resuscitation, at cut-offs of 5 exposures over three years for EMS-physicians (Bjornsson 2011 64) or 10 exposures over one-year for the lead paramedic (Weiss 2018 332), and unadjusted survival to hospital discharge.
Dyson (2016, 154) also found lower survival to discharge in patients treated by teams who hadn’t had an exposure in the preceding 6-months (AOR 0.70, 95% CI 0.54–0.91) compared to those with recent exposure (<1 month).
For the critical outcome of event survival we identified very low quality of evidence (downgraded for risk of bias and imprecision) from two non-RCTs (Bjornsson 2011 64; Weiss 2018 332). These two studies reported unadjusted outcomes and used the averaged exposure of team leaders to resuscitation over one (Weiss 2018 332) and three year study periods (Bjornsson 2011 64). These studies found no association between exposure to resuscitation, at cut-offs of 5 exposures over three years for EMS-physicians (Bjornsson 2011 64) or 10 exposures over one-year for the lead paramedic (Weiss 2018 332), and unadjusted event survival.
For the critical outcome of ROSC we identified very low quality of evidence (downgraded for risk of bias) from two non-RCTs (Tuttle 2018, 654; Weiss 2018, 332). The largest non-RCT (Tuttle 2018, 654) reported adjusted outcomes and examined the primary treating paramedic’s exposure in the preceding five years. This study found higher exposure of the treating paramedic was associated with increased ROSC: compared to <15 exposure reference group, ≥15 exposures (AOR 1.22, 95% CI 1.11–1.36). The other non-RCT (Weiss 2018, 332) also found an unadjusted association between ≥10 exposures for the lead paramedic over a one-year period and achievement of ROSC (OR 1.30, 95% CI 1.01–1.69).
Studies examining years of career experience
For the critical outcome of survival with favourable neurologic outcome at discharge/30 days we identified no studies.
For the critical outcome of survival to discharge/30 days we identified very low quality of evidence (downgraded for risk of bias and imprecision) from four non-RCTs (Dyson 2016 154; Gold 2009 341; Lukic 2016 591; Soo 1999 535). The largest and highest quality non-RCT (Dyson 2016 154) reported adjusted outcomes and examined the treating teams years of clinical experience and found no association with survival to hospital discharge: median ≤5 career years reference group, 5-8 years AOR=1.17 (0.99-1.39), 8-11 years AOR=1.11 (0.93-1.34), and >11 years AOR=1.09 (0.91-1.29). Two smaller non-RCTs, examined sub-groups of OHCAs, and also found no association with survival to discharge and the experience of the individual treating paramedics or treating EMS team (Gold 2009 341; Lukic 2016 591). The remaining non-RCT reported an association between increased survival to hospital discharge and technicians with >4 years’ experience (AOR 2.58, 95% CI 1.11-6.03, P=0.03) and paramedics with >1 year of experience (AOR 2.68, 95% CI 1.05- 6.82, P=0.04) (Soo 1999 535). However, this study did not fully account for the experience of the paramedics, as it did not include the previous career experience of paramedics as EMTs.
For the critical outcome of event survival we identified no studies.
For the critical outcome of ROSC we identified no studies.
We suggest that EMS systems: 1) monitor their clinical personnel’s exposure to resuscitation and 2) implement strategies, where possible, to address low exposure or ensure that treating teams have members with recent exposure (weak recommendation, very-low certainty of evidence).
Justification and Evidence to Decision Framework Highlights
- In making this recommendation the EIT Task Force prioritized the potential for improved patient outcomes through increased exposure, and with the understanding that knowledge and skills degrade over time and without use. We recognize that the evidence in support of this recommendation comes from observational studies of very low quality.
- Potential strategies to improve exposure include the rotation of EMS personnel through higher OHCA volume areas and ensuring treating teams include EMS personnel with recent exposure. However, the strategies employed are likely to vary between EMS systems.
- The EIT Task Force discussed the maintenance of resuscitation skills through team simulation. Team simulation has found to be effective for maintaining ALS skills in hospital settings, and are associated with improved patient outcomes (Andreatta 2011 33; Knight 2014 243). Such training may be a useful proxy for exposure in low exposure settings and for rare OHCA cases (e.g. pediatrics and neonates).
- The EIT Task Force also discussed the possibility of providing a target level for “ideal exposure”. However, it was decided more evidence is needed before exposure can be more accurately defined as the existing studies are conflicting. Dyson (2016, 154) report a linear relationship between survival and exposure, whereas Tuttle (2018, 654) report a levelling of survival at >15 exposure in the preceding 5 years.
- Only short term outcomes were evaluated, future studies should document neurologically intact survival to hospital discharge/30 days and adjust for potential confounders.
- Limited evidence to define low/ideal exposure to OHCA resuscitation.
- Limited evidence of exposure to OHCA rare cases.
- Interventional studies implementing strategies to improve EMS exposure to resuscitation
Evidence-to-Decision Table: Experience and Exposure
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Soo LH, Gray D, Young T, Skene A, Hampton JR. Influence of ambulance crew’slength of experience on the outcome of out-of-hospital cardiac arrest. Eur HeartJ 1999;20:535–40.
Tuttle JE, Hubble MW. "Paramedic Out-of-hospital Cardiac Arrest Case Volume Is a Predictor of Return of Spontaneous Circulation." The Western Journal of Emergency Medicine 2018; 19(4): 654-659.
Weiss N, Ross E, Cooley C, Polk J, Velasquez C, Harper S, Walrath B, Redman T, Mapp J, Wampler D. Soes Experience Matter? Paramedic Cardiac Resuscitation Experience Effect on Out-of-Hospital Cardiac Arrest Outcomes. Prehospital Emergency Care 2018; 22(3): 332-337.