Last Updated Oct 2012
Cystic fibrosis (CF; mucoviscidosis) is a genetic disease affecting all organs lined by an epithelium. In fact, the name cystic fibrosis is derived from the characteristic scarring and cyst formation within the pancreas initially recognized in the 1930s.
While these patients present multiple symptoms including sinus infection, diabetes, distal intestinal obstruction, poor growth and infertility, lung complications remain the major causes of morbidity and mortality. They experience frequent shortness of breath, coughing and chest infection due to their inability to clear abnormally thick and adhesive secretions.
This inherited disease is caused by mutations in the ion channel, named cystic fibrosis transmembrane regulator (CFTR), which is essential for proper hydration of airway surfaces. More than 1,400 mutations of the CFTR gene have been identified, and the most common (delF508) accounts for 90% of all cases in USA. Over 30,000 Americans carry CFTR mutations, and both parents must be a carrier for their child to have CF.
The following are what respiratory therapy, along with research, can do to help treat CF.
- Couples planning a pregnancy may undergo genetic testing to assess the risk that their child will be born with CF.
Mucociliary clearance is a critical defense mechanism against airway infection. Mucin is continuously secreted by the epithelium, hydrated by CFTR activity and moved upward with entrapped bacteria by coordinated cilia beating. In CF, the dehydrated surfaces lack the ability to unfold the long mucin strands, which form an adhesive viscoelastic mesh ideal for bacterial colonization. While several pathogens invade the airways, the first appearance of Pseudomonas aeruginosa represents a turning point in the disease. This bacterium has the unique ability to form a biofilm shielding the colony against host defenses. Excessive inflammatory responses mounted against this infection attack the integrity of the airway wall, causing a progressive decline in lung function. Eventually, breathing support may become necessary during sleep to maintain blood oxygen levels. A bilevel positive airway pressure ventilator pushes air into their lungs through a mask.
- In CF, disease severity is correlated with the age of P. aeruginosa acquisition.
Despite notable progress in antibiotic/antiinfective treatments, it remains impossible to eradicate pseudomonas aeruginosa infection. This is why preventive therapies aiming to delay the acquisition of P. aeruginosa in young CF patients are so important. A number of airway clearance therapies (ACTs) have been developed to dislodge mucin and encourage its expectoration, thereby preventing the accumulation of excess secretion which fosters bacterial colonization. In the hospital, respiratory therapists generally perform chest physiotherapy (CPT) by percussion/postural drainage or positive expiratory pressure (PEP). They also teach CF patients how to perform breathing exercises, including active cycles of breathing technique and autogenic drainage. The Cystic Fibrosis Foundation commissioned a review of all ACTs to establish comprehensive guidelines. To their surprise, they all provided comparable, but partial, relief of airway obstruction.
- Scientists and practitioners are working together to improve ACTs
A new generation of ACTs is now emerging based on scientific breakthroughs in our understanding of their effects on the airway wall. Studies showed that mechanical stress induces the release of ATP from the epithelia, which acts as a signaling molecule to stimulate clearance through an alternate ion channel capable of hydrating airway surfaces. Furthermore, we now know that mechanical stimulation must be rhythmic (oscillatory) to be efficient, such as tidal breathing. Based on this discovery, scientists and engineers joined forces to improve the efficiency of ACTs for CF patients. Daily percussion/postural drainage is being replaced by high frequency chest wall oscillation (HFCWO), a better-tolerated alternative to CPT which delivers vigorous, yet comfortable airway clearance treatment for CF patients. More importantly, HFCWO treatments are now available in the form of user-friendly portable airway clearance systems, namely the SmartVest® (Electromed, MN, USA) and the Vest® (Hill-Rom; CA, USA). While these vests are fairly expensive, they are now approved for reimbursement by over 900 insurance companies and 250 government-funded payers including Medicare part B.
This technological breakthrough reduces hospitalization and delays the acquisition of P. aeruginosa through regular and efficient HFCWO within the comfort of their home.
Over the past 20 years, the phenomenal progress in respiratory therapies addressing airway obstruction in CF is a testimony to the critical importance of maintaining active communications between clinicians, scientists and the Biotech/Pharma industry.
Just like some of the respiratory diseases such as bird flu, bronchitis, chronic obstructive pulmonary disorder, emphysema, influenza, common cold, tubercolosis, and whooping cough, cystic fibrosis may also be treated through respiratory therapy.
Click Here to read more about author Dr. Maryse Picher, Ph.D.
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