Dialling 999 (Medical Priority Dispatch System):


The Medical Priority Dispatch System (MPDS) is a medically approved system used by the NHS Ambulance Services of the UK to dispatch the most appropriate medical resource to the person making the call. (MPDS) requires the ambulance call handler to ask you a systemised series of key questions.


These questions allow the system to categorize the call by the chief complaint (What is wrong with the patient). The 999 call is then automatically categorized as to the level of response by the ambulance service.


Emergency 999 calls to the ambulance service are prioritised in two categories to ensure that life-threatening cases receive the quickest response. For this reason 999 should only be used for a genuine emergency.


You will be asked a series of questions and it is important that you do not hang up until they tell you that they have all the information they need. They may also talk you through how to give first aid until the ambulance arrives.


Guidelines when making 999 Call

You will be asked the following:


1. Case Entry:

  • Telephone number and location of incident. The Emergency Medical Dispatch (EMD) will ask you to verify these to ensure they have the correct information and an ambulance can be dispatched at this point in order to save time).
  • What is wrong (i.e. the 'chief complaint')?
  • Age of the patient.
  • Are they conscious?
  • Are they breathing?


2. Key Questions:

  • These are questions relevant to the chief complaint of the patient. If you are unsure or do not know the answer it is not a problem and will not delay the ambulance.


3. In case of illness (over 35 years):

  • Is there any chest pain?


4. In cases of accident or injury:

  • Is there any severe bleeding?


5. Post dispatch Instructions:

  • These are given if appropriate at the end of the call to advise the caller what they can do to help the patient if they are not a qualified First Aider or Medical Professional.


6. Pre-arrival Instructions:

  • These are protocol driven instructions given for life-threatening emergencies until the arrival of the ambulance.


The EMD will also require a rendezvous point from you where the ambulance will be met and directed to the patient.



We hope you find this article useful. This is one in an alphabetical series of articles addressing various symptoms and their first aid treatments. If you would like more information on related resuscitation and first aid training, please get in touch.


You might also be interested in our blog 'When is it appropriate to call an ambulance' by Clive Haddrell.


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