Cystic fibrosis (CF) is caused by a mutation in the cystic fibrosis transmembrane regulator (CFTR) gene, affecting the function of the CFTR protein. This protein is responsible for the movement of chloride ions across cell membranes, in turn building a salt gradient that powers the movement of water across cells.

Disturbances in the workings of the CFTR protein within the mucus-producing cells compromise the transport of water across these cells, and result in the production of thick, sticky, and obstructive mucus. Removing this mucus is very important to preventing infections in the airways, and to making it easier for CF patients to breathe.

Physiotherapy can help with mucus clearance in CF patients. Two common physiotherapy techniques used in CF are described below.

Postural drainage and percussion

Postural drainage and percussion (PD&P) is a two-step procedure. The first step, postural drainage, involves using gravity-assisted methods to facilitate the drainage of mucus from the smaller airways in the lungs. This is accomplished by alternating the patient’s body positions in a manner that allows the flow of mucus towards larger airways, using gravity.

The exercise involves shifting the body in two upright sitting positions, and four positions where the head is positioned below the lungs. These maneuvers loosen out the mucus and help the patients expel out thick sticky mucus by coughing.

The next step involves tapping the patient with gentle but effective and steady percussions, or claps, using the palm of the hand. This creates vibration and aids in loosening the mucus. The percussions should be targeted in the right area, using the palms to tap the person between the collarbones and the top of the shoulder blades. In some cases, the patient may be trained to do these exercises themselves — a process referred to as self-percussion.

Proper training and professional physiotherapy are required for these maneuvers, since percussion wrongly done may lead to injury or organ damage. For example, it is important to avoid areas such as the spine, breastbone, stomach, and the lower ribs or back to prevent injury to the spleen, liver, or the kidneys. It is extremely important that caregivers discuss plans for PD&P a clinician and physiotherapist before trying these methods.

Active cycle of breathing techniques (ACBT)

ACBT are breathing exercises involving three steps that alternate between relaxing the patient’s airways, getting air behind mucus, and forcing the mucus out of the lungs.

The first step is breathing control. It involves breathing in through the nose and then, using little force, gently exhaling through the mouth. This step is repeated about six to eight times in order to relax the patient’s lungs.

Next comes chest expansion exercises (also called thoracic expansion exercises), which involve breathing air in deeply, holding the air in the lungs for three to five seconds, and then breathing out very gently.  The intent of this step is to get air behind the mucus so it can move up the airways and eventually be expelled.

The last step involves huffing (also called a forced expiratory technique), or breathing out inhaled air through an open mouth and throat in a controlled manner. This helps move mucus into larger airways, and a goal is to expel the mucus.

These exercises should be supervised initially. A clinician or physiotherapist can gradually guide and train the patient in doing these exercise independently.

Other airway clearance techniques often used with CF include high-frequency chest wall oscillation, positive expiratory pressure (PEP), oscillating positive expiratory pressure (oscillating PEP), inhaled therapy, oxygen therapy, and the use of inhalers and nebulizer systems.


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