Choking occurs when a foreign object becomes lodged in the throat or windpipe, blocking the flow of air. In adults, a piece of food/ vomit etc often is the culprit because choking cuts off oxygen to the brain, administer first aid as quickly as possible.

The universal sign for choking is hands clutched to the throat. If the person doesn't give the signal, look for these indications:

• Inability to talk Difficulty breathing or noisy breathing Inability to cough forcefully Skin, lips and nails turning blue or dusky Loss of consciousness

If choking is occurring, begin to perform the Heimlich manoeuvre. If you're the only rescuer, perform the Heimlich manoeuvre before calling 911 (or your local emergency number) for help.

If another person is available, have that person call for help while you perform the Heimlich manoeuvre.

To perform the Heimlich manoeuvre on someone else:

• Stand behind the person. Wrap your arms around the waist. Tip the person forward slightly. Make a fist with one hand. Position it slightly above the person's navel. Grasp the fist with the other hand. Press hard into the abdomen with a quick, upward thrust — as if trying to lift the person up. * Repeat until the blockage is dislodged.

To perform the Heimlich manoeuvre on yourself:

• Place a fist slightly above your navel. * Grasp your fist with the other hand and bend over a hard surface — a countertop or chair will do. * Shove your fist inward and upward.

Clearing the airway of an unconscious person:

• Lower the person on his or her back onto the floor. Clear the airway. If there is a visible blockage at the back of the throat or high in the throat, reach a finger into the mouth and sweep out the cause of the blockage. Be careful not to push the food or object deeper into the airway, which can happen easily in young children. If the object remains lodged and the person doesn't respond after you take the above measures, begin cardiopulmonary resuscitation (CPR). The chest compressions used in CPR may dislodge the object. Remember to recheck the mouth periodically.