What is Cystic Fibrosis?
What is Cystic Fibrosis?
Cystic fibrosis (CF) is a genetic disease affecting approximately 30,000 children and adults in the United States. Around 1,000 new cases of CF are diagnosed each year. CF occurs in one of every 3,200 live Caucasian births and in one of every 15,000 African-American births. CF is less common in Asians and Native Americans, but is being seen more often in Hispanics. More than 80 percent of patients are diagnosed by age three; however, almost 10 percent of new diagnoses are age 18 or older. About 3 % of patients with CF are diagnosed in adulthood.
In CF, mucus glands do not secrete normal, free-flowing fluid. Instead, a defective gene causes the body to produce abnormally thick, sticky mucus, which blocks ducts and other passageways in the body, particularly in the lungs and intestines interfering with vital functions such as breathing and digestion. In the lungs, these thick secretions clog airways leading to recurrent infections. Thick secretions also obstruct the pancreas, preventing digestion and absorption of fats and fat-soluble vitamins, leading to nutrition deficiencies and intestinal complications.
According to the CF Foundation's National Patient Registry, the median age of survival for a person with CF is 35 years. As more advances have been made in the treatment of CF, the number of patients with CF living into adulthood has steadily grown. Today, nearly 40 percent of the CF population is age 18 and older. Adults may experience additional health challenges including CF-related diabetes and osteoporosis.
Cystic Fibrosis is currently incurable. Ten years ago, the life expectancy of a person with CF was an average of 18 years. Advances in research and treatment have helped extend median survival to greater than 33 years. Early diagnosis, aggressive therapy, continued research, and routine check-ups are essential to patient health. With proper care, many patients with CF are living into adulthood and leading normal, productive lives.
Cystic Fibrosis is not contagious. It is a genetic or inherited disease, beginning at conception from a defect or abnormality of a gene. More than 10 million Americans are unknowing, symptom-free carriers of the defective CF gene. An individual must inherit two defective CF genes -- one from each parent -- to have CF. Each time two carriers conceive, there is a 25 percent chance that their child will have CF; a 50 percent chance that the child will be a carrier of the CF gene; and a 25 percent chance that the child will be a non-carrier.
Symptoms vary from person to person due to the fact that more than 1,000 mutations of the CF gene exist. CF symptoms develop during the first years of life of most patients, although they may not be obvious in young children and blamed initially on other causes. In approximately 10-15% of the cases, the earliest symptom of CF appears at birth in the form intestinal blockage, called meconium ileus, which usually requires surgical removal. The lungs and pancreas produce the most common symptoms, usually respiratory and gastrointestinal complications. The lesser symptoms involve the reproductive tract and sweat glands.
At some time in their lives, patients with CF develop lung disease. The thick mucus produced in CF blocks the airways interfering with normal breathing and eventually leading to lung damage. Respiratory symptoms include recurrent infections such as chronic cough, wheezing, shortness of breath, pneumonia, bronchitis, bronchiectasis; pneumothorax; hemoptysis; digital clubbing; cor pulmonale; sinusitis; nasal polyps; and allergic bronchopulmonary aspergillosis. Your physician and health team will assist you in creating a respiratory treatment plan to help keep your lungs healthy and prevent lung damage.
Pneumonia - lung infection with consolidation, which can be caused by a number of organisms. Patients with CF are at risk for infections as the abnormal mucus and reduced water content in the airways enhances growth of bacteria.
Bronchiectasis – chronic, recurrent respiratory infections lead to permanent lung damage, which is the leading cause of mortality in CF patients. Bronchiectasis is the chronic dilation of the airways allowing them to be filled with mucus, leading to infection, which leads to even more damage.
The pancreas and other organs of the digestive system secrete enzymes into the intestine where they help to break down food, which the body uses for energy, growth, and maintenance. In CF thick, sticky mucus blocks the passageways that carry these enzymes to the intestines. This results in poor digestion and the food eaten cannot be used by the body. Because of the increased metabolic demands on the body by the respiratory disease, added with malabsorption of the food, the individual with CF often has a large appetite, but still may appear under nourished. Symptoms of pancreatic insufficiency are found in 90% of patients with CF. These include an excessive appetite but poor weight gain; and greasy, bulky, foul smelling stools; meconuim ileus; distal intestinal obstruction; gastroesophageal reflux; hyperglycemia; abdominal discomfort; liver disease; and rectal prolapse.
Meconium ileus – meconium refers to a newborn’s first stool, which is thick, sticky, dark green, and odorless. Ileus refers to an obstruction in the intestine. In babies with meconium ileus, the bowel is blocked with very thick meconium prohibiting passing of stool. This occurs in approximately 10-15% of newborns with CF.
Distal intestinal obstruction – similar to meconium ileus, it is a syndrome occurring in children and young adults with CF. It results from improperly digested fats and proteins, which form a mass and block intestines. Symptoms include right lower side pain, loss of appetite, and vomiting.
Hyperglycemia – high blood sugar resulting from insufficient insulin. The pancreas is responsible for producing insulin, which converts sugar (glucose) into energy. A small percentage of patients with CF will have diabetes, but it usually doesn’t appear until 20-30 years of age. Symptoms that might occur are thirst, dry mouth, and frequent urination.
Liver disease (cirrhosis) – liver complications include a fatty liver; biliary fibrosis caused by blocked bile ducts leading to inflammation, leading to fibrosis, leading to development of gallstones.
Reproductive tract complications include delayed puberty in both male and female patients with CF. This is thought to be due to nutritional inadequacies. Most males with CF (more than 95%) are azoospermic due an absence of the vas deferens (tube which carries sperm from testis to urethra) making them sterile, but with new technologies some are becoming fathers. Sexual function is not impaired. About 20% of females are infertile due to effects of chronic lung disease on menstrual cycle and thick mucus on cervix impedes movement of sperm. If a woman wants to get pregnant, she should know the risks. Limited lung function and other health factors may make it difficult to carry a child to term. The added demands of childcare and how it will effect personal health should also be considered. CF alone is not a method of birth control. Sexually active patients should discuss birth control options with their physician. Some antibiotics make oral contraceptives less effective. Some patients may also have liver disease or diabetes that should be considered. Safe sex and protection from STD is vital for all.
The effect of CF on the sweat glands results in a high concentration of salt in perspiration. This is due to the abnormal transport of chloride across the cell membrane. During periods of increased sweating, such as during exercise, elevated temperature, or hot weather, this salt loss can but patient at risk for heat exhaustion and dehydration.
The sweat test is the number one diagnostic test for CF. It is the simplest and most reliable method of diagnosing CF by determining an abnormally high salt content in the sweat. It involves using a chemical and a mild electric current to stimulate skin to sweat, wrapping the stimulated area with plastic and a pad to absorb the sweat, and collecting the sweat for analysis after 45 minutes-1 hour. A concentration of chloride greater than 60 mmol per litre is a positive indication for CF. A sweat test should be performed at a CF Foundation-accredited care center where strict guidelines are followed to ensure accurate results.
Medical history is essential in diagnosing CF, as several symptoms will provide a physician with important clues. Because CF is an inherited disorder, a family history of CF might also suggest the gene might be present.
A genetic test, also called a genotype or mutation analysis, can analyze DNA for presence of one of the several hundred mutations that can cause CF. This test involves collecting a blood sample. This test cannot detect all of the mutations that cause CF, so reliability is around 85%.
Other less common forms of diagnostic testing include Immunoreactive Trypsinogen Test (IRT) and Nasal Potential Difference (NPD) measurement.
IRT may be performed in newborns who can’t produce enough sweat for the sweat test. This is a blood test that evaluates the presence of the protein trypsinogen. If the test is positive, it should be confirmed by a mutation analysis. The combination of these two test is sensitive to 90%-100%. With NPD, a surface electrode measures the electric potential difference (the amount of energy required to move an electrical charge from one point to another) as the Na+ (sodium) and Cl- (chloride) ions move across the cell membranes in the lining of the nasal passages.
Prenatal genetic testing can be performed to determine if the unborn child has CF, although this test is not foolproof. Amniocentesis involves removing cells from the amniotic fluid surrounding the fetus. Chorionic villus biopsy involves sampling tissue that develops into the placenta. Because prenatal genetic screening is expensive and carries some risk to the mother, not all women who are CF carriers choose to have these tests.
Since there is no cure for CF, many different kinds of therapy have been developed to decrease the progression of the disease. The treatment of CF depends upon the stage of the disease and the organs involved. Both symptomatic and preventative treatment is important to fight active infections and maintain pulmonary health. Your healthcare team will assist in developing a treatment plan that is right for you.
Clearing mucus from the lungs is an important part of the daily CF treatment regimen since lung involvement accounts for most of the morbidity and mortality. Thick secretions hinder the method that normally moves mucus out of the lungs (the mucocilliary escalator). If these secretions are not cleared, they can block the airways. The mucus also provides an ideal place for bacteria to grow and multiply resulting in chronic lung infections. Chest physical therapy (CPT) is a form of airway clearance done by vigorous clapping on the back and chest using drainage positions to dislodge the thick mucus from the lungs. 3-5 minutes of clapping over specific areas of the chest combined with drainage positions is essential. Comfortable attire should be worn such as a soft T-shirt. Avoid clapping over buttons and seams. A CPT treatment takes approximately 30-45 minutes. CPT should be performed before meals or at least an hour after a meal. A respiratory therapist will provide you with written and verbal instruction on proper technique as well as demonstration and adherence tips. How often CPT is performed daily will depend on each patient’s individual health.
Alternative methods of airway clearance exist, but depend on age and size of patient, cooperation, and technique. Once a patient reaches age of 2 years and a chest circumference of 20-23 inches, the physician may introduce the The Vest system to replace CPT. The Vest system works by high-frequency oscillation of chest wall to remove secretions. A respiratory therapist will provide you with information on the proper settings and technique of performing The Vest therapy as well as order of inhaled medications used in conjunction with The Vest therapy. Older patients (5 years and up) may be able to perform PEP therapy. PEP works by having patient exhale through a restricted opening creating a build up of backpressure in the lungs. This pressure results in the expansion of the small airways and opens side channels to get behind mucus and move secretions forward to the large airways where they can be coughed out. The patient will perform active cough maneuvers to remove secretions. Some PEP devices have a vibration capability, such as the Acapella or Flutter. This vibration furthers mucus clearance. The key to PEP therapy is proper technique otherwise, treatment is not effective. A respiratory therapist will provide instruction on proper technique. PEP therapy is usually used as an adjunct to CPT or The Vest therapy, instead of a replacement therapy. Most PEP devices are small making device an alternative to take on trips, camp, school, or vacation. Another device that may be used in the hospital is called an Intrapulmonary Percussive Ventilator (IPV). IPV works using percussive bursts of air to maintain a pressure wedge while high speed flows open airways and enhance secretion mobilization. These prolonged percussive intervals will expand the lung, mobilize secretions, and deliver aerosolized medications to the peripheral airways. There are IPV machines available for home use, but these expensive devices are not covered by most insurance policies.
Aerosol therapy will be another part of the daily regimen. The purpose of aerosol therapy is to deliver a fine mist of medication into the lungs. Necessary equipment includes a compressor, which blows air into a nebulizer or “cup” changing liquid medicine into a mist. Aerosol treatments are given to infants with a mask and are given with mouthpiece to older children (6 years and up). A respiratory therapist will help demonstrate how to administer different aerosol medications and provide the proper equipment. There are several different aerosol medications prescribed for a patient with CF. The most common is Albuterol, a bronchodilator that helps open the airways. Albuterol is given prior to or during CPT to aid in secretion clearance. Other types of inhaled medication include Pulmozyme®, a mucus-thinning drug shown to reduce the number of lung infections and improve lung function, can be given prior to CPT or during The Vest therapy; TOBI® (tobramycin solution for inhalation), an aerosolized antibiotic used to treat lung infections should be given after airway clearance therapy; inhaled corticosteroids (Pulmicort Respules, Flovent, Advair), to reduce inflammation and swelling in tissues of airways, should be given after airway clearance and before TOBI®.
Dietary management is important for each patient with CF the goal being to provide enough nutrition ( webmaster - link to nutrition on main page for more information) for maximum growth. This means a balanced diet of high calories, protein, other nutrients, enzymes, and vitamin supplements. A nutritionist will help create a dietary management plan. Sometimes patients cannot eat enough calories in their regular diet to maintain or gain weight. Milkshakes and high-calorie nutritional supplements that come in ready-to-drink preparation, powders to mix as a drink, or sprinkle on food can be prescribed. A few individuals may not be able to take in enough calories orally to maintain or gain weight. In these special cases, calories in the form of a liquid formula can be given to a patient by a feeding tube directly into the stomach or intestine overnight while they sleep. These feeding tubes can be placed in a number of different ways. A nasogastric tube (NG-tube) is inserted nightly through the nose, down the throat, and into the stomach. A gastrostomy tube (G-tube) is surgically placed through the skin in the upper abdomen and into the stomach. A Jejunostomy (J-tube) is similar to gastrostomy except tube is inserted into part of intestine instead of stomach protecting against reflux. The idea of a “tube” of any sort is scary at first, but the dramatic growth results will win out. Many patients and families feel relief when they don’t have to fuss and fight about eating or feel they now have to force themselves to eat so much. Your physician will help decide what is best for you.
Mucus blocks the tiny tubes in the pancreas of people with CF meaning the pancreatic digestive enzymes are not secreted into the intestine. These enzymes are responsible for breaking down fat, starch, and protein that can then be absorbed. 90% of all CF patients benefit from pancreatic enzyme replacement therapy (PERT). The adequacy of pancreatic function can be evaluated by inspecting the stools for greasiness, frothy appearance, foul odor, bulkiness, or by laboratory test calculating fat in stools (fecal fat study). Enzymes should be given prior to each meal and snack. Enzyme preparation and dosage will be determined for each patient based on diet, weight gain, and bowel movements. Dosage will need to be readjusted periodically as patient grows. There are different brands of enzymes including Ultrase, Creon, Pancreacarb, pancrease, and cotazyme. Your nutritionist and physician will assist in selecting your pancreatic enzyme replacement therapy.
Enzymes work best in an alkaline environment, so sometimes even when they reach the intestines the effects are reduced by the high acid content. H2 blockers are a type of drug that helps reduce the stomach acid. They are prescribed for some patients with CF in efforts to create a more alkaline environment so the pancreatic enzymes can do their job. They also can help break up clumps of undigested food that lead to distal intestinal obstruction.
Vitamins A, D, E, and K require fat to be absorbed. Since CF patients have difficulty digesting and absorbing fat, these vitamin levels are often low. Patients will be placed on daily vitamin supplements based on age. This dose is higher than that recommended for persons without CF. To make vitamins easier to absorb, they can be taken with meals when enzymes are supplied. Care should be taken not to leave vitamins and enzymes in the car as the heat can break down medication and make it less effective. Store in a cool environment.
Exercise and physical fitness are important in maintaining muscle strength, endurance, flexibility, and general good health. Exercise should be encouraged in children and young adults with cystic fibrosis as regular exercise will help clear mucus from the lungs, build up respiratory muscles, and improve ability to breathe. We recommend consistent aerobic activity for 30-60 minutes a day, to be added in addition to airway clearance therapy. This can be in the form of running, jumping rope, swimming, or dancing. Extracurricular activity in various sports should be encouraged. Just remember to drink plenty of fluid to prevent dehydration and boost calories to prevent weight loss.