Cystic Fibrosis Flashcards
What is cystic fibrosis?
Cystic fibrosis (CF) is an incurable, hereditary disease caused by a mutation in the gene for the protein cystic fibrosis transmembrane conductance regulator (CFTR). The mutation causes abnormal transport of chloride, bicarbonate and sodium ions across the epithelium, leading to thick, viscous secretions. The thick mucus affects the lungs, pancreas, liver and intestines, which causes difficulty breathing, lung infections and digestive complications
What is the average life expectancy of someone with cystic fibrosis?
The average life expectancy of a person with CF is 35-40 years with more than 75% of patients being diagnosed by 2 years of age
How is cystic fibrosis diagnosed?
Newborn screening is performed in the US in the first 2-3 days after a baby is born. NBS includes testing for CF and other conditions. If the initial screening identifies a risk of CF, then a sweat chloride test is performed to confirm the diagnosis
What is a sweat test?
The sweat test measures the amount of salt (chloride) in the sweat, which is high in patients with CF
What are the classic symptoms of CF?
The classic symptoms of CF are salty tasty skin, poor growth and poor weight gain, thick and sticky mucus production, frequent lung infections, coughing and shortness of breath. Patients experience obstruction of pancreatic ducts causing steatorrhea (fatty stools) and poor absorption of nutrients. Clubbing of the fingers may be present
What is the goal of therapy for CF?
The primary goals of therapy include preventing/treating lung infections, maintaining adequate nutrition and optimizing quality of life
What medications do CF patients typically receive?
Most patients will receive airway clearance therapies, inhaled antibiotics targeting Pseudomonas aeruginosa and pancreatic enzyme replacement
What is the order for inhaled interventions for CF?
1) Inhaled bronchodilators: opens the airways
2) Hypertonic saline: mobilizes mucus to improve airway clearance
3) Dornase alfa: decreases viscosity of mucus to promote airway clearance
4) Chest physiotherapy: Mobilizes mucus to improve airway clearance
5) Inhaled antibiotics: controls airway infection
What is the importance of inhaled therapies for CF?
Inhaled therapies are the foundations of treatment in CF. The drug is delivered directly to the lungs, resulting in minimal systemic absorption (reducing the risk of toxicity). Although inhaled medications are an effective form of drug delivery, the average patient with CF receives up to 10 doses of inhaled medications daily, which can take 2-3 hours to administer
What are the most common organisms seen early in CF?
The most common organisms seen early in the disease are Staphylococcus aureus and Haemophilus influenzae, followed by Pseudomonas aeruginosa in adolescents and adults
How is acute pulmonary exacerbations characterized?
Acute pulmonary exacerbations are characterized by an increase in cough, sputum production with a change in sputum color (greenish), shortness of breath and a rapid decline in FEV1
What is included in the treatment of acute pulmonary exacerbations?
Treatment often includes an extended course of antibiotics (2-4 weeks) and modalities to increase airway clearance
What medications can be used for infections caused by Pseudomonas aeruginosa?
For infections caused by Pseudomonas aeruginosa, two IV drugs are recommended to provide potential synergy and prevent resistance. These include aminoglycosides, beta-lactams, quinolones and others that cover Pseudomonas aeruginosa
Describe the doses used for treating Pseudomonas in patients with CF.
Doses end to be larger than normal to address altered pharmacokinetics in patients with CF, obtain therapeutic drug concentrations in lung tissue and to overcome reduced susceptibility of the bacteria chronically colonizing the airways
What is recommended for CF patients with chronic Pseudomonas aeruginosa?
Inhaled antibiotics are recommended for patients with chronic Pseudomonas aeruginosa lung infections to reduce the bacterial burden. treatment is cycled with 28 days on therapy, followed by 28 days off
If a patient is given inhaled aztreonam, what is the normal dosing and why is it optimal dosing?
Inhaled aztreonam is dosed TID and should be scheduled as close to every 8 hours as possible. This dosing provides optimal bacterial killing around the clock, while minimizing the time when the antibiotic concentration is low (which can worsen resistance)
How is inhaled tobramycin dosed?
Inhaled tobramycin is dosed every 12 hours and should be scheduled as close to every 12 hours as possible with at least 8 hours in between doses
When can azithromycin be considered for chronic infection of Pseudomonas?
A 6 month trial of oral azithromycin can be considered for patients with chronic infection who are worsening on conventional treatment. Azithromycin has no direct bactericidal activity against Pseudomonas, but disrupts biofilm formation by the bacteria which can improve lung function and decrease exacerbations
What are some examples of inhaled airway clearance therapies?
Bronchodilator, hypertonic saline, dornase alfa (Pulmozyme)
What are some notes about hypertonic saline?
- Hypertonic saline is supplied as small ready-to-use vials that are delivered via a nebulizer
- PulmoSal is buffered to match physiologic pH of airway surface
- Hypertonic saline is a high-alert drug, especially with IV administration
