title: The wake-effect--emergency vehicle-related collisions.
abstract: BACKGROUND
  Emergency medical vehicle collisions (EMVCs) occurring during initial response and with patient transport have been a long-standing problem for emergency medical services (EMS) systems. Experience suggests "wake-effect" collisions occur as a result of an EMS vehicle's transit, but do not involve the emergency medical vehicle (EMV). Substantiating the existence and magnitude of wake-effect collisions may have major implications regarding the manner of EMV response.
  
  
  OBJECTIVE
  Paramedics will report that wake-effect collisions do occur and that they occur more frequently than do EMVCs.
  
  
  METHODS
  
  
  
  METHODS
  Survey analysis.
  
  
  METHODS
  Thirty paramedics employed by the Salt Lake City (Utah) Fire Department and 45 paramedics employed by Salt Lake County Fire Department. Geographic Area: Service area has population of 650,000 and is urban, suburban, and rural.
  
  
  METHODS
  The survey consisted of three open-ended questions concerning years on the job, EMVCs, and wake-effect collisions.
  
  
  METHODS
  The mean value for the number of EMVCs and wake-effect EMVCs, along with the 0.95 confidence intervals (0.95 CI) were determined.
  
  
  RESULTS
  Seventy-three surveys were analyzed. Sixty EMVCs and 255 wake-effect collisions were reported. Overall, the mean value for the number EMVCs per respondent was 0.82 (0.60-1.05) and for wake-effect collisions 3.49 (2.42-4.55). The mean values for EMVC's for each service were 0.86 (0.50-1.38); 0.80 (0.50-11.0). For wake-effect collisions the mean values were 4.59 (2.83-6.35); and 2.76 (1.46-4.06) respectively.
  
  
  CONCLUSIONS
  This study suggests that the wake-effect collision is real and may occur with greater frequency than do EMVCs. Significant limitations of this study are recall bias and misclassification bias. Future studies are needed to define more precisely wake-effect collision prevalence and the resulting "cost" in regards to injury and vehicle/property damage.
authors.affiliation: Gold Cross Ambulance and Medical Priority Consultants, Salt Lake City, UT 84111, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Clawson
authors.forename: R L
authors.initials: RL
authors.lastname: Martin
authors.forename: G A
authors.initials: GA
authors.lastname: Cady
authors.forename: R F
authors.initials: RF
authors.lastname: Maio
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000552:Ambulances / Q000706:statistics & numerical data*; D003625:Data Collection; D004631:Emergency Medical Service Communication Systems / Q000706:statistics & numerical data*; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D012307:Risk Factors; D013997:Time Factors; D014589:Utah