TABLE 1.

Definitions for EMS Event Intervals

EMS Event IntervalDecision Rule
Discovery intervalEstimated time last seen to time EMS notified (dispatch called)
Call-response intervalTime EMS unit notified (dispatch called) to time of BLS or ALS arrival at scene
Scene-intervalTime of BLS or ALS arrival at scene to time EMS unit left scene
Minutes to CPRIf the arrest is witnessed and with bystander CPR or the arrest occurs in the presence of EMS, then minutes to CPR = 0
If arrest is witnessed and without bystander CPR, minutes to CPR = time EMS unit notified (dispatch called) to time BLS or ALS arrived at scene
If arrest is unwitnessed and without bystander CPR, minutes to CPR = estimated time last seen to arrival of BLS or ALS at scene
If arrest is unwitnessed and with bystander CPR on discovery, minutes to CPR = time patient last seen to time EMS unit notified (dispatch called)
Start-stop CPR intervalIf bystander CPR present, start-stop CPR interval = the time EMS unit notified (dispatch called) to time of ROSC or death
If patient arrested in presence of EMS providers or there is no bystander CPR, start-stop CPR interval = time of EMS unit arrival to time of ROSC or death
Transport intervalTime EMS unit left scene to time of arrival in ED
Sustained ROSCIf known ROSC >20 min or ROSC in the field or in the ED that results in the patient being admitted to the hospital alive
  • BLS, indicates basic life support; ALS, advanced life support.