It has been estimated that approximately 20 per cent of the patients who call 112 search medical help for acute chest pain with suspected acute coronary syndrome, i.e. acute myocardial infarction and unstable angina.. However, acute chest pain is most likely associated with anxiety. Studies on patients with acute myocardial infarction show that pain intensity before arriving to hospital is more apparent than afterwards. This is reason enough to believe that a caring relationship and benzodiazepines in addition to morphine would promote pain relief. However, randomised comparative treatment studies are few. Thus, the overall aim of this study is to reduce the feeling of anxiety as a strong component in acute chest pain. The degree of pain is assessed on a ten-grade scale by the patient. The design is an educational as well as a medical intervention. The educational intervention is a course that aims to increase awareness in ambulance nurses regarding relieving and treating chest pain and anxiety with a caring relationship together with knowledge in cardiology. The medical intervention is Midazolam. The education is conducted in 2007-2010. The collection of data started in May, 2008 and lasted throughout 2010. The project is conducted by an interdisciplinary research group, ambulance doctors and experienced ambulance nurses.

The Lindrastudien tests two hypotheses:

Hypothesis 1: The combination of morphine/midazolam relieves pain better than morphine alone.

Hypothesis 2: Nurses who are specially trained in the care of patients with acute coronary syndrome relieve pain better than nurses who do not have this expertise.

The significance of the study can be described in terms of that a more effective pain management increases patient well-being and may possibly reduce the risk of complications.