Cystic Fibrosis


Article Author:
Elaine Yu


Article Editor:
Sandeep Sharma


Editors In Chief:
David Wood
Andrew Wilt
Hajira Basit


Managing Editors:
Avais Raja
Orawan Chaigasame
Khalid Alsayouri
Kyle Blair
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beenish Sohail
Hajira Basit
Phillip Hynes
Sandeep Sekhon


Updated:
3/13/2019 5:54:21 PM

Introduction

Since ancient times, children around the world have been afflicted with cystic fibrosis that leads to shortened lifespans. In medieval Europe, these children were believed to be cursed by witches and doomed to die. The curse that became folklore pronounced, “Woe to the child who tastes salty from a kiss on the brow, for he is cursed and soon will die.” Salty skin was a sign of an impending illness without cause or cure.  Until relatively modern times, cystic fibrosis was poorly understood. In 1949, Lowe et al. postulated that cystic fibrosis must be caused by a genetic defect from the autosomal recessive pattern of inheritance of the disease. High levels of salt in the sweat of patients with cystic fibrosis suggested an abnormality in electrolyte transport from the sweat gland. Quinton postulated that sweat ducts in these patients were impermeable to chloride. Further studies led to the hypothesis that the faulty chloride channel must be situated in the apical membranes of the lung surface or glandular epithelium to explain the respiratory and systemic organ failure associated with cystic fibrosis.  Researchers now know that cystic fibrosis is an autosomal recessive disorder of exocrine gland function most commonly affecting persons of Northern European descent at a rate of 1:3500.  It is a chronic disease that frequently leads to chronic sinopulmonary infections and pancreatic insufficiency. The most common cause of death is end-stage lung disease.[1][2][3][4]

Etiology

CF is caused by a genetic mutation in a gene on chromosome 7 that codes for a protein transmembrane conductance regulator (CFTR) protein which functions as a transmembrane cAMP-activated chloride channel. Both copies of the gene are mutated in clinical disease.

There are over 2000 different mutations in the CFTR gene that can cause disease. These mutations are divided into 5 classes:

  1. Defective protein synthesis
  2. Defective protein processing
  3. Disordered regulation
  4. Defective chloride conductance
  5. Accelerated channel turnover[5]

Epidemiology

The most common mutation is delta F508 which is found in 70% of American Caucasian CF patients and two-thirds of all cases worldwide. This mutation is a class 2 mutation of abnormal folding of the CFTR protein, leading to premature destruction within the Golgi apparatus. The delta F508 mutation commonly leads to exocrine pancreatic insufficiency and a higher likelihood of meconium ileus.[6]

Pathophysiology

Class 1 dysfunction is the result of nonsense, frameshift, or splice-site mutation which leads to premature termination of the mRNA sequence. This fails to translate the genetic information into a protein product with a subsequent total absence of CFTR protein, and approximately 2% to 5% of cystic fibrosis cases result.

Class 2 dysfunction results in abnormal post-translational processing of the CFTR protein. This step in protein processing is essential for the proper intracellular transit of the protein. As a result, CFTR is unable to be moved to the correct cellular location.

Class 3 dysfunction is characterized by diminished protein activity in response to intracellular signaling. The result is a fully formed protein channel in the cellular membrane that is non-functional.

Class 4 dysfunction is when the protein is produced and correctly localized to the cell surface. However, the rate of chloride ion flow and the duration of channel activation after stimulation is decreased from normal.

Class 5 dysfunction is the net decreased concentration of CFTR channels in the cellular membrane as a result of rapid degradation by cellular processes. It includes mutations that alter the stability of mRNA and others that alter the stability of the mature CFTR protein.

The result of all mutations is decreased secretion of chloride and consequently increased resorption of sodium into the cellular space. The increased sodium reabsorption leads to increased water resorption and manifests as thicker mucus secretions on epithelial linings and more viscous secretions from exocrine tissues. Thickened mucus secretions in nearly every organ system involved result in mucous plugging with obstruction pathologies. The most commonly affected organs include the sinuses, lungs, pancreas, biliary and hepatic systems, intestines, and sweat glands.

Sinus disease occurs when secretion viscosity increases which obstruct the sinus ostia. Additional processes often exist here. These include ciliary dysfunction, increased inflammatory mediators, and increased bacterial colonization with pathogens such as Pseudomonas aeruginosa. The result of this syndrome is impaired sinus secretion clearance. Subsequently, chronic sinusitis occurs and secondary structural damage may occur.

Lung disease occurs as a spectrum obstruction from thickened mucous secretion. It is important to note that the lungs of a CF patient are normal in utero, at birth, and after birth. Disease results as a cascade effect following infection and the subsequent inflammatory process. Mucus plugging in the bronchioles results in an obstructive lung disease clinical picture. As a result of obstruction, an environment optimal for bacterial growth is created within the airways. Bronchiectasis and further thick purulent sputum production occur.  Part of the inflammatory reaction includes the production of the neutrophil interleukin-8 from epithelial cells which functions as a secretagogue increasing mucous secretion, thereby creating a positive feedback loop of mucous secretion with persistence of inflammation, infection, and structural damage. The result of this cascade is obstruction of the airways with resulting failure of ventilation of the lung. Poorly managed pulmonary manifestations are the primary cause of death in CF patients.

Pancreatic manifestations of CF are due in large part to obstruction of the pancreatic ductules by thickened secretions. On the passage of gastric contents into the proximal duodenum, the pancreatic exocrine glands are triggered to excrete pancreatic enzymes into the luminal space of the small intestines. However, increased viscosity of excretions and obstruction of the pancreatic ductules inhibits this process. The net pH of the secretions lessens due to decreased sodium bicarbonate composition lending to a lesser neutralization of the acidic stomach chyme. The lower pH chyme effectively degrades what pancreatic enzymes reach the intestinal lumen.  As a result, intestinal chyme is not enzymatically processed in the intestines resulting in the pathognomonic greasy stools, colicky abdominal pain, and malabsorption of nutrients from foods. Specifically, fat-soluble vitamins A, D, E, and K are notably deficient. Furthermore, autodigestion of the pancreas may occur as these enzymes target the pancreatic tissues.  This results in pancreatitis. In severe, chronic cases this can lead to endocrine pancreatic failure when the islets of Langerhans begin to be digested by trapped pancreatic enzymes. The lasting impacts of this spectrum of disease mimic type-1 diabetes mellitus.

Increased secretion viscosity does not spare the biliary and hepatic systems. The biliary ductules may be plugged with secretions. Obstructive cirrhosis and post-hepatic hyperbilirubinemia can occur. Secondary to this, esophageal varices, splenomegaly, and hypersplenism may occur as a result of increased hepatic portal vein pressures. Gallbladder disease is more likely to occur as a spectrum of this manifestation of CF with up to 15% of those with cystic fibrosis having gallstones.

Intestinal involvement is typically seen in children with meconium ileus at birth and intestinal obstruction later in life. The cause of meconium ileus is multifactorial. Likely, it is due to increased fluid absorption as a result of the faulty CFTR channel with dehydration of the intestinal contents leading to constipation coupled with a change in luminal contents from normal secondary to pancreatic insufficiency as discussed above.  Mechanical obstruction chronically leads to inflammation and eventual scarring and stricture formation. This may lead to further intestinal obstruction by fecal impaction or intussusception later in life.

Sweat glands offer an interesting contrast to all other tissues containing CFTR channels in that the flow of chloride is reversed.  Normally, sweat glands move chloride from the extracellular space into the intracellular space. Thus, sodium and water are reabsorbed from the sweat gland tissues into the body. However, failure of the chloride channel to reabsorb chloride leads to a loss of sodium onto the skin surface and a subsequent fluid loss. This causes the pathognomonic salty skin seen with cystic fibrosis. In prolonged or warm environments or more severe cases, this may lead to hyponatremic dehydration.

In addition to acting as a chloride transport protein, other interactions of CFTR have been postulated. In the apical plasma membrane, CFTR is part of a multiprotein assembly where three of its amino acids, threonine, arginine, and leucine, act to root the protein to a region known as PDZ-type receptors. These PDZ regions have been observed to occur in multiple intracellular signaling proteins associated with the plasma membrane as well. This also roots CFTR closely to other transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements. These interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and in vivo. It seems that these close associations may allow for CFTR to play an important role in epithelial cells beyond as an ion channel. While not yet fully understood, modulation of CFTR in animal studies proved that inflammatory responses, maturational processing, non-chloride ion transport, and intracellular signaling are related to its function. These other interacting proteins are potential modifiers of the cystic fibrosis phenotype and may help explain the substantial differences in clinical severity between similar genotypic CF patients.[7][8][9]

History and Physical

Newborns with CF may present with meconium ileus, prolonged neonatal jaundice, or early lung infection. Infants and children with CF may present with failure to thrive and poor weight gain, anemia, undescended testicles in boys, recurrent sinopulmonary infections, and a distal intestinal obstructive syndrome with or without pancreatic insufficiency. The median age of diagnosis is 6 to 8 months; although, individuals may not exhibit clinical signs and symptoms until later.

Adults with CF often present with exacerbations of one or more symptoms. Lung manifestations of CF include chronic bronchitis, abnormal pulmonary function tests, bronchiectasis, atypical asthma, allergic bronchopulmonary aspergillosis, and colonization with P. aeruginosa. Sinus manifestations of CF include chronic rhinosinusitis, chronic post-nasal drip, nasal polyposis, and panopacification of the paranasal sinuses. Pancreatic manifestations include pancreatic insufficiency, recurrent pancreatitis, and early-onset diabetes. Hepatobiliary manifestations include focal biliary cirrhosis, cholelithiasis, periportal fibrosis, liver cirrhosis, portal hypertension, and variceal bleeding. Musculoskeletal manifestations include kyphoscoliosis, osteopenia/osteoporosis, and arthropathy. Hematologic manifestations include iron-deficiency anemia or anemia of chronic disease leading to splenomegaly. Nephrogenic manifestations include nephrolithiasis, nephrocalcinosis, hyperoxaluria, and hypocitraturia. Dermatologic manifestations include “salty sweat,” digital clubbing, and cyanosis. Additional dermatologic conditions due to malabsorption include acrodermatitis enteropathica due to zinc deficiency and scaly dermatitis associated with fatty acid deficiency. Finally, males may be infertile due to an absent vas deferens while females have reduced fertility due to thickened cervical mucus.

Evaluation

In the United States, newborns are screened for CF as part of a standard newborn screening panel. Some cases of CF are discovered on prenatal ultrasound which may demonstrate meconium peritonitis, bowel dilation, or absent gallbladder. Such findings often lead to prenatal CF carrier screening.[10][11][12][13]

To diagnose CF, the following criteria must be met:

Suspicion for Cystic Fibrosis

  1. Sibling with cystic fibrosis
  2. Positive newborn screen
  3. Clinical symptoms consistent with CF in 1 or more organ systems
  • Chronic sinopulmonary disease
  • Gastrointestinal or nutritional abnormalities
  • Salt loss syndromes
  • Obstructive azoospermia

Evidence of CFTR Dysfunction

  1. Elevated sweat chloride 2 than 60 mEq/L on two occasions
  2. Two disease-causing CFTR mutations
  3. Abnormal nasal potential difference

The diagnostic pathway starts with a sweat chloride test. If normal but still symptomatic, a repeat sweat chloride test is indicated. If the test is abnormal, DNA testing is indicated. If 1 or less CFTR mutations are found, expanded DNA analysis is indicated. However, the finding of 2 CF-related mutations confirms the diagnosis of cystic fibrosis.

The test for immunoreactive trypsinogen (IRT), a pancreatic enzyme, increases sensitivity and specificity in screening newborns with meconium ileus for CF. IRT monitoring can be correlated with the severity of CF and when it drops below detectable levels can indicate the need to start pancreatic enzyme replacement.

Additional diagnostics may be indicated depending on the presenting symptoms. A chest x-ray may help identify hyperinflation, bronchiectasis, abscesses, or atelectasis. Sinus radiography may demonstrate panopacification of the paranasal sinuses. Abdominal radiology may be helpful in neonates who present with meconium ileus. Bronchoalveolar lavage typically shows many neutrophils, and microbiology is commonly positive for Haemophilus influenza, Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia, Escherichia coli, or Klebsiella pneumonia.

Pulmonary function testing is a major tool for evaluating and monitoring disease state and progression in CF. Spirometry is the commonly used pulmonary function test. It measures the volume of air exhaled during a forceful and complete exhalation after a maximal inhalation. The total exhaled volume, known as the forced vital capacity (FVC), the volume exhaled in the first second, known as the forced expiratory volume in one second (FEV1), and their ratio (FEV1/FVC) are the most important variables reported. These values allow for interpretation of the status of the lung ventilation function. These values are compared to an expected normal for age, height, and gender to generate an expected normal value. The measured value is then calculated as a percent of normal where normal equals 100%. A normal or high FEV1 and/or a low FVC may indicate restrictive lung disease. A low FEV1 with a high FVC indicate obstructive lung disease with airway trapping. Cystic fibrosis can be expected to show air trapping patterns with low FEV1 values proportional to the severity of the disease.[14]

Treatment / Management

Cystic fibrosis is a systemic illness that has broad implications for both quality and quantity of life when poorly controlled. Therefore, treatment should focus on optimizing function to avoid acute illness events. This should target maintaining lung function by aggressively controlling respiratory infection and clearing airways of mucus, optimizing nutritional status with pancreatic enzyme supplements and multivitamins, and finally by managing any other health complications that may arise. This is best performed when using a team approach of specialists who are experienced in managing cystic fibrosis.[15][16][17][18][15]

As stated previously, pulmonary disease is the most common cause of mortality in cystic fibrosis. As such, it is extremely vital to have a low threshold for diagnosis and intervention in pulmonary illness exacerbations. A pulmonary exacerbation is the worsening of lung function due to an infection. Often this is characterized by shortness of breath, fatigue, productive cough, and fever. Pulmonary function testing will worsen from baseline during an exacerbation. Any acute illness should prompt admission to a hospital facility familiar with cystic fibrosis management.

Pulmonary illness should be managed with 2 primary goals: treat the infection and improve oxygenation. P. aeruginosa typically induces infectious etiologies, and antibiotic therapy should have spectrum coverage against this pathogen. However, sputum culture should be obtained and a sensitivity profile obtained for the pathogens present. CF guidelines recommend at least 1 antibiotic to cover each pathogenic bacteria cultured from respiratory secretions and 2 antibiotics for P. aeruginosa infections. Mild exacerbations may be amenable to oral antibiotics, but more severe exacerbations require intravenous medication use. Inhaled antibiotics are not recommended whenever an intravenous alternative is possible. Ventilation and oxygenation should be supported through the use of inhaled bronchodilators including albuterol and ipratropium bromide. Agents such as inhaled dornase alfa or inhaled hypertonic saline are prescribed to promote airway secretion clearance in conjunction with chest physiotherapy. Anti-inflammatory medicines such as glucocorticoids are also used to assist in opening airways to relieve the obstruction. The work of breathing should be optimized utilizing nasal cannula oxygen when appropriate. BiPAP ventilation may be necessary to overcome airway trapping. Intubation with mechanical ventilation is an option but should be avoided whenever possible and used only when respiratory failure is imminent.

Chronic, supportive therapy for patients with CF includes regular pancreatic enzymes, fat-soluble vitamins (A, D, E, K), mucolytics, bronchodilators, antibiotics, and anti-inflammatory agents.

A new class of medications known as CFTR modulator therapies is designed to correct the dysfunction by improving production, intracellular processing, or function of the CFTR protein caused by the mutated gene. Each medication is targeted at a specific dysfunction caused by specific gene mutation. Ivacaftor is used in the treatment of class 3 dysfunctions where a mutation at G551D is the primary aberration. It acts by binding the defective CFTR protein at the cell surface and opening the chloride channel, thus restoring the proper function of the protein. This was the first medication to directly impact the protein channel rather than treating the effects of CF.  Dosing for patients older than six years is 150 mg by mouth every 12 hours. Younger patients should receive weight-based dosing where those with less than 14 kg body weight receive 50 mg by mouth every 12 hours and those with greater than 14 kg body weight should receive 75 mg by mouth every 12 hours. Lumacaftor is a chaperone molecule that was designed to move the defective CFTR protein from the intracellular organelles where it is processed and onto the cell surface. As such, it is effective in delta F508 homozygous mutation genotypes. Clinically, this medicine has no benefit when given alone. However, when combined as lumacaftor/ivacaftor has been shown in the 92-week PROGRESS study to have modest benefits for patients who tolerate the medicine in both pulmonary function testing and body mass index (BMI). This medicine combination was subsequently approved for use in a patient older than 6 years old. Dosing is 2 tablets containing lumacaftor 200 mg/ivacaftor 125 mg taken orally every 12 hours. Another medication combination currently in clinical trials is tezacaftor/ivacaftor. Tezacaftor as a medicine is very similar to lumacaftor in that it is a CFTR protein chaperone that improves the intracellular processing and trafficking of CFTR. Likewise, its clinical efficacy is only seen when placed in combination with ivacaftor. This medicine is showing a good safety profile and preliminary EVOLVE and EXPAND trials are indicating less side effect profiles compared to lumacaftor/ivacaftor.

Despite major advancements in medical therapies for CF, the disease process still continues to advance, and the lungs will ultimately fail prematurely from the disease burden without surgical intervention. Lung transplant is the treatment of choice for end-stage lung disease. The timing of transplant is multifactorial. The International Society of Heart and Lung Transplantation published a list of conditions to be used when considering transplant referral and takes into consideration the 5-year predicted survival of less than 50%, the FEV1 that has fallen to 30% of predicted values, rapidly falling FEV1 despite optimal therapy, a 6-minute walk distance of less than 400 meters, the development of pulmonary hypertension in the absence of a hypoxemic exacerbation, clinical decline characterized by increasing frequency of exacerbations including acute respiratory failure requiring noninvasive ventilation, a pattern of poor clinical recovery from successive exacerbations, worsening nutritional status despite supplementation, pneumothorax, or life threatening hemoptysis despite bronchial artery embolization.  Virtually all lung transplants for CF will need replacement of both lungs. This is because a native, diseased lung would act as a source of infected secretions which would threaten the transplanted lung and possibly induce respiratory failure. It is important to note that transplantation is not a cure for CF, but it confers a prolongation of life and offers significant symptomatic relief.

Diet and Exercise

Individuals with CF are encouraged to consume a high-fat diet with supplemental fat-soluble vitamins to compensate for malabsorption. Additionally, patients living with CF are encouraged to consume a high-calorie diet to maintain a healthy weight and combat the chronic inflammation and frequent infections that are commonly encountered. According to the Cystic Fibrosis Foundation, women should consume 2500 to 3000 calories a day, while men should consume 3000 to 3700 calories a day. Those living in hot climates or who participate in activities that cause sweating are encouraged to consume additional sodium in their diet. Oral feedings are preferred, however, if intake does not meet metabolic demand as determined by continued decreases in BMI, enteral (tube) feedings should be considered. These are typically in the form of gastric tube feedings or jejunal tube feedings. Multiple control studies of enteral nutrition in CF patients have shown benefit in the form of improved, or neutral lung function following exacerbations of illness that directly correlate with BMI. With that noted, however, no randomized studies of enteral nutrition have been performed in patients with CF to date. Parenteral nutrition may be considered only when oral or enteral nutrition is not meeting metabolic needs. Parenteral nutrition has been linked to increased risk for sepsis events and should be used sparingly. Regular exercise is encouraged in patients with CF to maintain and support lung function.

Differential Diagnosis

  • Asthma
  • Bronchiolitis
  • Bronchiectasis
  • Celiac disease
  • Nutritional considerations in failure to thrive
  • Pediatric Aspergillosis
  • Primary ciliary dyskinesia
  • Sinusitis

Prognosis

CF patients are estimated to live until about the fourth decade of life before requiring lung transplantation. Lung transplantation confers a median survival of 8.5 years.

Enhancing Healthcare Team Outcomes

Cystic fibrosis is a systemic illness that has broad implications for both quality and quantity of life when poorly controlled. Therefore, treatment should focus on optimizing function to avoid acute illness events. This should target maintaining lung function by aggressively controlling respiratory infection and clearing airways of mucus, optimizing nutritional status with pancreatic enzyme supplements and multivitamins, and finally by managing any other health complications that may arise. This is best performed when using a team approach of specialists who are experienced in managing cystic fibrosis. Lung infections continue to have the highest mortality rates. For children who undergo a lung transplant, survival is increased for 6-8 years but without a lung transplant, most children are dead within a few years.


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Cystic Fibrosis - Questions

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An eight-year-old patient with cystic fibrosis is scheduled for postural drainage. Which of the following will loosen secretions and thin airway mucus?



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What is the cause of death in the majority of patients with cystic fibrosis?



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What is the median survival in patients with cystic fibrosis (CF)?



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Which of the following radiological features is a strong indication that a patient may have cystic fibrosis?



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A 24-year-old male has a long history of respiratory tract infections. He and his wife have fertility problems. Semen analysis reveals obstructive azoospermia. What is the most likely diagnosis?



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Findings of which of the following organisms in the sputum support the diagnosis of cystic fibrosis (CF) in children?



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Patients with cystic fibrosis usually develop which condition?



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Genetic counseling is sought by a white couple, both of whom have a sibling who has cystic fibrosis. What method should be used to screen the couple?



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Cystic fibrosis (CF) screening uses polymerase chain reaction (PCR) to identify relevant regions of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. PCR DNA polymerase is highly resistant to which of the following?



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Which of the following is the most probable etiology in the case of a young adult male with a chronic productive cough, recurrent pulmonary infections, diabetes, and chronic diarrhea who is diagnosed with bronchiectasis on chest x-ray?



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The cystic fibrosis CFTR gene is located on which chromosome?



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In a 4-month-old with rectal prolapse, the sweat chloride reveals a concentration of 57 meq/L (normal is less than 60 mEq/L). What test should be performed next?



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Which screening test is used to check for cystic fibrosis (CF) in newborns?



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Genetic counseling is sought by a white couple, both of whom have a sibling with cystic fibrosis. What method should be used to screen the couple?



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What is the most common serious inherited recessive disease in children in North America?



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Which part of the respiratory system is mainly involved in cystic fibrosis causing excess production of viscous mucus?



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A young adult male with recurrent pulmonary infections, diabetes, and chronic diarrhea presents with a productive cough. He noticed a few streaks of blood as he coughs up sputum. A chest radiograph is performed. The image is provided below. Which of the following is the most probable etiology for this patients presentation?

(Move Mouse on Image to Enlarge)
  • Image 1685 Not availableImage 1685 Not available
    Contributed by Scott Dulebohn, MD
Attributed To: Contributed by Scott Dulebohn, MD



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What is the main occupational therapy focus in a child with cystic fibrosis?



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When is the best time to perform chest percussion in an infant with cystic fibrosis?



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Which of the following will be elevated in the sweat of a patient with cystic fibrosis?



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What level of sweat chloride is suggestive of cystic fibrosis?



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What type of inheritance does cystic fibrosis exhibit?



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What is the probability that an infant will develop cystic fibrosis (CF) when both parents have the trait?



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What is the probability that a child will be a carrier when both parents have the trait of cystic fibrosis?



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Which is a common feature of cystic fibrosis in children?



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Which feature is often seen in patients with cystic fibrosis (CF)?



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Which is a common therapy in patients with cystic fibrosis (CF)?



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A newborn does not pass meconium and starts vomiting all feedings. She develops abdominal distention but the anus is patent. Radiograph of the abdomen reveals no free air or luminal distension. Bubbly feces are seen. Select the most likely diagnosis.



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Which of the following tests would be most useful in the evaluation of an infant with failure to thrive, recurrent respiratory infections, and diarrhea in whom you suspect cystic fibrosis?



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A 6-month-old infant presents with rectal prolapse. Which of the following tests is best to diagnose the infant's condition?



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A 6-month-old patient with rectal prolapse with suspected cystic fibrosis has a sweat chloride test concentration of 58 mEq/L. What test should be done next?



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Which of the following vitamins is expected to be deficient in cystic fibrosis patients?



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Which of the following vitamins are most likely to be deficient in cystic fibrosis (CF)?



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Select the organism least likely to be cultured from the sputum of an individual with cystic fibrosis.



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A 40-year-old male complains of a chronic cough despite treatment with albuterol and fluticasone inhalers. He has been treated with numerous antibiotics with improvement lasting only a short time. His symptoms started about 20 years ago. The patient's vital signs are normal, but the lung exam shows dullness to percussion over the upper lobes and bilateral wheezing. There is mild clubbing but no other findings. Pulmonary functions show an obstructive pattern. Chest radiograph shows bilateral upper lobe infiltrates, and sputum culture grows Pseudomonas aeruginosa. Which of the following will most likely lead to the diagnosis?



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A child with a history of a chronic cough and meconium ileus as a neonate in the developing world presents to you. He most likely also suffers from which of the following?



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Which of the following is true regarding cystic fibrosis?



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Which test is used to diagnose cystic fibrosis?



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Which condition can be treated with chest physiotherapy?



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A child with a history of recurrent pneumonia is referred for evaluation when she is found to have 2 CFTR mutations and a sweat chloride of 64 mmol/L on a pilocarpine iontophoresis. These results are most consistent with which of the following?



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Which is the most common, lethal, genetic disease in whites?



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Which of the following populations has the highest prevalence of cystic fibrosis in the United States?



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What is true of respiratory secretions in patients with cystic fibrosis?



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A 6-year-old girl is admitted with pneumonia and has physical findings of rhonchi, wheezes, and digital clubbing. The patient has a history of thick mucus, frequent respiratory infections, and pancreatic insufficiency. What is the most likely underlying condition?



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Which of the following is the etiology of cystic fibrosis?



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Which of the following is true of cystic fibrosis?



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Which of the following describes the defective process that occurs in cystic fibrosis (CF)?



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Which of the following organs is most affected by the thick mucous produced in cystic fibrosis?



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Which of the following is an accurate statistic concerning cystic fibrosis?



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Which of following is the most predominant cause of death in cystic fibrosis?



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Which of the following is a focus of treatment for patients with cystic fibrosis?



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Which of the following is true regarding cystic fibrosis?



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Which of the following have the highest incidence of cystic fibrosis?



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A gram-negative organism is found in unusually high numbers in the mucus of a cystic fibrosis patient. Which of the following virulence factors is most important in colonization and maintenance of the organism in the lungs?



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A one-day-old female infant develops bilious emesis and abdominal distention. The plain radiograph shows dilated loops of small bowel without air fluid levels and bubbly intestinal contents noted in the right lower quadrant. Diatrizoate enema shows microcolon. Which of the following is the most likely diagnosis?



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A 9-month-old male has had several episodes of pneumonitis and has a persistent cough. There has been poor weight gain and the mother reports large foul-smelling stools. Select the best diagnostic test.



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A 3-month-old is not gaining weight and has fatty stools. The laboratory cannot obtain enough sweat to make the diagnosis of cystic fibrosis. What test should be ordered?



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Which of the following diseases presents with meconium ileus?



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What percentage of patients with cystic fibrosis (CF) have developed liver disease by young adulthood?



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Which of the following is least functionally affected by cystic fibrosis?



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The most frequent imaging finding in patients with cystic fibrosis is which of the following?



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A 3-day-old male is found to have a positive cystic fibrosis screen on his newborn exam. Along with respiratory distress, it is found that his digestive enzymes are likely not to be converted into their active forms for proper digestion and absorption. Which of the following organ-enzyme associations is expected to be involved later in his life due to this disease process?



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A 38 -year-old man with chronic pancreatitis presents with unintentional weight loss and diarrhea. Analysis of a 24-hour stool sample shows 30 g of fat, leading to the conclusion that the man has fat malabsorption. The man is also infertile and has suffered multiple episodes of respiratory infections starting from childhood. Which of the following vitamins is most likely deficient in this man?



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Cystic fibrosis causes difficulty with absorption of which one of the following?



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Which of the following usually needs to be supplemented in patients with cystic fibrosis?



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The mother of a patient with cystic fibrosis comes in for a refill of her son's pancreatic enzymes prescription. The exact formulation/brand they have been getting is on manufacturer back-order. In order to do a therapeutic substitution to an agent with a slightly different formulation, which enzyme of equivalent dose should be prescribed?



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Which of the following is true regarding cystic fibrosis? Select all that apply.



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A nurse is caring for a male infant with meconium ileus, neonatal jaundice, and pneumonia. The sweat chloride test is positive. What are the potential complications associated with the infant's condition? Select all that apply.



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A nurse is responsible for the care of a client with cystic fibrosis. Which of the following are appropriate supportive measures and are included in client and caregiver education? Select all that apply.



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Which of the following is a potential complication of cystic fibrosis? Select all that apply.



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A child with cystic fibrosis was recently admitted to the pediatric unit with wheezing and copious airway secretions. What are critical nursing interventions to implement in the plan of care for this patient? Select all that apply.



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A client with cystic fibrosis is likely to develop a deficiency of which vitamin? Select all that apply.



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In a patient with cystic fibrosis, which gastrointestinal tract manifestations can occur? Select all that apply.



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A child has just been diagnosed with cystic fibrosis. Which of the following respiratory tract manifestations will likely occur? Select all that apply.



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Cystic Fibrosis - References

References

Lyamin AV,Ismatullin DD,Zhestkov AV,Kondratenko OV, [The laboratory diagnostic in patients with mucoviscidosis: A review.] Klinicheskaia laboratornaia diagnostika. 2018;     [PubMed]
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