Prepulse Inhibition and the Call Alert in Emergency Medical Services

In emergency medical services (EMS), paramedics are most often informed of an emergency call by an audible radio alarm called the call alert. The call alert used by Alberta Health Services Emergency Medical Services (AHS EMS) is loud and sudden, and therefore it likely evokes a startle response in paramedics. The call alert has been identified as a significant source of occupational stress and is associated with sudden cardiac death and disproportionately high rates of heart disease in first responders. While more than 40 years of research have demonstrated that call alerting has detrimental physical and psychological effects on paramedics and other first responders, only two mitigation strategies have been proposed and investigated.

The present study determined if the current AHS EMS call alert was startling and if a novel mitigation strategy, the addition of a prepulse, could make it less so. Fifty paramedics were exposed to two call alerts of each type. Their responses were measured using EMG assessments of blink magnitude, ECG measures of heart rate, and visual analogue scale reports of signal intensity and dislike. The findings were statistically analyzed using ANOVAs and t-tests.

Participants demonstrated significant startle blinks consistent with an acoustic startle response pattern and changes in heart rate suggestive of a cardiac startle and a cardiac defensive response. These findings support the hypothesis that the call alert is startling. The addition of a prepulse to the existing call alert resulted in decreased magnitude startle blinks and reduced perceptions of sound intensity and dislike, suggesting that a prepulse effectively reduces paramedics' startle magnitude.

The current study demonstrates that the AHS EMS call alert causes a psychophysiological response in paramedics and that a prepulse effectively moderates this reaction. Future research may find that less startling call alerts improve paramedics' mental and physical health at a minimal cost. EMS leadership can use the findings of this investigation to make informed choices about how paramedics are alerted of the need to respond.