• The tongue
• Swelling of the throat
• Food
• Vomit
• Foreign objects

• Noisy, laboured breathing
• A bluish colouration of the skin, lips or nails (Cyanosis)
• Flaring of the nostrils
• Reversed movement of the chest while breathing, i.e. the chest wall will suck in as the casualty breathes out
• Drawing in of the chest wall between the ribs and the soft spaces above the collar bones and breastbone

If the casualty is unconscious, open the airway - lie the casualty on his back and tilt his head back - check breathing and pulse and be prepared to resuscitate. If the airway is blocked there are different ways of removing the obstruction:

• Finger sweep - On an unconscious casualty incline the head to one side and under direct vision sweep the object out with one finger. DO NOT attempt just to feel the object. If you cannot see it try something else. DO NOT attempt to put your fingers into the mouth of a conscious casualty, it will cause great distress and may push the object further down the throat.

• Back Slaps - Conscious and unconscious casualties can benefit from this procedure. A child or infant can be placed over the knee to aid the process. Unconscious casualties should be put into the prone position.

• Aspirator - Where the airway is blocked by blood, vomit or other fluids use the aspirator to remove it. Before inserting the aspirator, line up the tube alongside the casualty's face. Place the end of the tube level with the ear lobe and put your thumb and forefinger on the tube where it's level with the corner of the mouth. Keeping your thumb and forefinger on the tube insert it into the casualty's mouth no further than your thumb and forefinger and repeatedly squeeze the trigger. Be sure not to point the back of the aspirator at you or anyone else!

1. If the casualty is breathing, encourage him to cough, as this will help to dislodge the obstruction. Check the mouth and remove obvious obstructions if possible.
2. If the casualty seems to be weakening, or stops coughing or breathing, stand to the side and slightly behind him, remove obvious obstructions from the mouth and give five sharp slaps to his back, between the shoulder blades. Check the mouth again.
3. If the back slap fails, you need to give five abdominal thrusts (The Heimlich Manoeuvre). Stand behind the casualty and place your arms around his abdomen, bend him slightly forwards and put your clenched fist just below the base of the breastbone. Put your other hand on top and pull sharply inwards and upwards five times. Listen for the obstruction being dislodged. Check the mouth again.
4. If the blockage does not clear repeat steps 2 & 3 three times.
5. If the above fails call 999.

This video illustrates the above sequence very well.