Postural drainage and chest percussion are often used together to help loosen and remove mucus from the lungs. These airway clearance techniques help people who have a spinal cord injury, cystic fibrosis, or another condition that makes it hard for mucus to drain from the lungs. When mucus collects in your lungs, it increases your risk for lung infections.
Postural drainage uses gravity to help drain mucus into the mouth by placing the body in specific positions. Each position drains different areas (lobes) of the lung. The mucus can then be spit or coughed out.
Chest percussion (chest physiotherapy) uses clapping of the chest with a cupped hand to vibrate the airways in the lungs. This vibration moves the mucus from smaller airways into larger ones where it can be coughed up. Chest percussion is done with the help of a partner, special electronic devices designed to vibrate the chest, or other instruments that a person can use to vibrate the chest safely.
A doctor or respiratory therapist will recommend how often to do these techniques. They usually need to be done at least once a day. It is important to do them exactly as you are instructed.
Morning can be a good time to do postural drainage, to help clear mucus that has built up during the night. When postural drainage is done just before bedtime, it may help decrease coughing at night. Do not do it soon after a meal, because this may raise your chance of reflux or vomiting.
See pictures that show where to clap: