Cardiac arrest is the term used to describe any sudden cessation of the heart, characterized by absence of pulse and breathing. Cardiac arrest may be the result of severe heart attack, anaphylactic shock (see p.450), electric shock, poisoning (including drug overdose), hypothermia or suffocation.
During cardiac arrest, the brain and heart muscle are completely starved of oxygen, a state that can be tolerated for only a few minutes before permanent damage results. It is vital, therefore, that resuscitation procedures are instigated immediately.
Cardiac Arrest Resuscitation
Resuscitation is the emergency action required when there is sustained interruption of the oxygen supply to the brain. In order that this vital oxygen supply may be restored, three vital conditions must be met:
A. The airway must be clear in order to permit oxygen-rich air to enter the lungs.
B. There must be adequate breathing taking place in order that the oxygen can enter the bloodstream.
C. The blood must be pumped around the body providing effective circulation to the brain and all body tissues.
When presented with an unconscious casualty, it is important to assess his or her condition quickly before attempting resuscitation. It is therefore important to ask the following questions:
1. Is the casualty unconscious with no evidence of pulse or breathing? If so, dial 999 for an ambulance and carry out artificial ventilation and chest compression until the ambulance arrives.
2. Is the casualty unconscious and not breathing but with the pulse still present? If so, give 10 breaths of artificial ventilation and dial 999 for an ambulance. Continue artificial ventilation until the ambulance arrives or spontaneous breathing is resumed. Check the pulse frequently.
3. Is the casualty unconscious but breathing with pulse present? If so, treat any obvious injuries, dial 999 for an ambulance and place the casualty in the recovery position.
A Open the Airway
1. Remove any visible obstructions from the mouth.
2. Placing two fingers under the casualty's chin, gently raise the jaw. Simultaneously, tilt the casualty's head well back by applying gentle pressure to the forehead with your other hand. Sometimes the airway may be blocked by the tongue as a result of loss of muscular control during unconsciousness, and this man oeuvre will lift the tongue clear.
B Check for Breathing
Place your face close to the casualty's mouth and listen and feel for breathing for a full ten seconds. At the same time look along the chest and the abdomen for signs of movement.
C Check the circulation
If the heart is not beating adequately, there will be an absence of movement and breathing and the casualty may have an abnormal color. Check the casualty's condition for ten seconds before commencing resuscitation.
Mouth to mouth or artificial ventilation
If the casualty is not breathing then breathing the exhaled air from your lungs into his or hers may keep them adequately ventilated until help arrives.
- Place the casualty flat on the back and ensure the airway is open. Remove any obvious obstructions from the mouth. (Broken or loose dentures should be removed, but well fitting dentures should remain in place).
- Pinch the casualty's nose “between” the index finger and thumb. Take a deep breath then form a seal around the casualty's mouth with your lips.
- Blow steadily into the mouth until the chest rises. Each full inflation should take about two seconds.
Remove your lips from the casualty's and allow the chest to 'exhale', or fall, fully before giving a subsequent breath.
If the chest fails to rise
- Check that the head is tilted back correctly.
- Ensure that your lips are forming a proper seal around the casualty's mouth.
- Check that air is not escaping from the nostrils.
- Check that the airway is not blocked by vomit or blood. If an airway obstruction is suspected then finger sweeps may be performed on an adult. Keep the casualty's head tilted back and sweep your finger round the mouth and hook out any obstruction but do not extend the fingers into the casualty's throat. (This man oeuvre is not suitable for children).
- The first aider should administer a further three breaths and check the casualty again. If this is not effective and no one else is available to call an ambulance then give ventilation for a full minute before going to contact medical help.