There is evidence that an accelerated heart rate is linked to increased illness. In ambulance personnel there appears to be an increased post-traumatic risk. Previous studies of stress related to the ambulance profession have focused on personal estimation or the measurement of blood pressure.
One study has shown that the alarm itself is a stressor, or strain, which increases the heart rate of ambulance personnel.

The study Is heart rate an equally accurate marker of stress as salivary cortisol? tests the hypothesis that the heart rate of ambulance personnel correlates to cortisol in saliva.

A pilot study will be conducted. All the personnel at an ambulance station will be asked to participate. Five persons will be selected at random. The subjects will wear a pulse monitor for continuous measurement of their heart rate. Two salivary cortisol series will be submitted at a priority 1 alarm. Each series includes four cortisol tests:

1.  at an alarm
2. when the patient is moved into an ambulance
3. after the handover report at the hospital and
4. on return to the station.

As a reference, two control samples will be taken on two different days off at the same time as the alarm (once at home and once at work). In addition to this, each participant will submit diurnal urine for the measurement of urinary cortisol levels (one day at home and one day at work).

The study is important for shedding light on the degree of stress that ambulance personnel are exposed to. In the longer term, these studies are planned to encompass in-depth interviews to further evaluate adverse reactions in ambulance personnel in connection with priority 1 assignments. The longer term envisages the possibility of mental training.