Circulation

Once oxygen can be delivered to the lungs by a clear airway and efficient breathing, there needs to be a circulation to deliver it to the rest of the body.

Non-breathing patients

Circulation is the original meaning of the 'C' as laid down by Jude, Knickerbocker & Safar, and was intended to suggest assessing the presence or absence of circulation, usually by taking a carotid pulse, before taking any further treatment steps.

In modern protocols for lay persons, this step is omitted as it has been proven that lay rescuers may have difficulty in accurately determining the presence or absence of a pulse, and that, in any case, there is less risk of harm by performing chest compressions on a beating heart than failing to perform them when the heart is not beating. For this reason, lay rescuers proceed directly to cardiopulmonary resuscitation, starting with chest compressions, which is effectively artificial circulation. In order to simplify the teaching of this to some groups, especially at a basic first aid level, the C for 'Circulation' is changed for meaning 'CPR' or 'Compressions'.

It should be remembered, however, that health care professionals will often still include a pulse check in their ABC check, and may involve additional steps such as an immediate ECG when cardiac arrest is suspected, in order to assess heart rhythm.

Breathing patients

In patients who are breathing, there is the opportunity to undertake further diagnosis and, depending on the skill level of the attending rescuer, a number of assessment options are available, including:

• Observation of colour and temperature of hands and fingers where cold, blue, pink, pale, or mottled extremities can be indicative of poor circulation
• Capillary refill is an assessment of the effective working of the capillaries, and involves applying cutaneous pressure to an area of skin to force blood from the area, and counting the time until return of blood. This can be performed peripherally, usually on a fingernail bed, or centrally, usually on the sternum or forehead
• Pulse checks, both centrally and peripherally, assessing rate (normally 60-80 beats per minute in a resting adult), regularity, strength, and equality between different pulses
• Blood pressure measurements can be taken to assess for signs of shock
• Auscultation of the heart can be undertaken by medical professionals
• Observation for secondary signs of circulatory failure such as oedema or frothing from the mouth (indicative of congestive heart failure)
• ECG monitoring will allow the healthcare professional to help diagnose underlying heart conditions, including myocardial infarctions
  

source: wikipedia.org