Cystic fibrosis Flashcards
What is the genetics of cystic fibrosis?
Autosomal recessive disorder
If both parents are carriers what are the chances that children will have CF, not have and be a carrier of CF?
1 in 4 chance child has CF
2 in 4 chance child is a carrier
1 in 4 chance child is unaffected
Why does CF occur?
CF occurs due to mutation in the transmembrane conductance regulator protein (CFTR) which is coded in chromosome 7.
What does a defected CFTR protein result in?
Abnormal transport of chloride and sodium causing:
- Reduced airway surface liquid (dehydrates mucous layer)
- Thick sticky mucous
- Shearing
- Impaired bacterial killing via neutrophils
How is CF tested for?
Antenatal testing
Neonatal screening
Sweat test
What does antenatal testing involve?
Pre-implantation genetic diagnosis
Chorionic villous sampling
Amniocentesis
- Amniotic fluid removed and tested
What does neonatal screening involve?
Newborn heal prick on day 5
Guthrie test
- If positive refer for clinical assessment and sweat test
What does a sweat test measure and the results in CF patients?
Measures concentration of chloride excreted in sweat.
In CF patients this is elevated
(>60 millimoles per litre is abnormal)
What effect does CF have on the body?
Makes all fluid in the body thicker
(mucous, semen, tears etc.)
How does CF affect the lungs?
Infection and bronchiectasis
Haemoptysis
Pneumothorax
Asthma fungal infection
Respiratory fatigue
Cor pulmonale
What effect does CF have on nutrition?
Increased energy need with a reduced intake
- leads to difficulty gaining and keeping weight on
Vitamin deficiency
What effect does CF have on the reproductive system?
Male infertility
Pregnancy
Delayed puberty
What effect does CF has on the GI and liver?
Pancreatic insufficiency
Diabetes
Liver disease
Meconium Ileus
Cirrhosis, portal HT
Malabsorption
GI dysmotility
Distal intestinal obstruction
Reflux
Coeliac disease
What are some other effects of CF?
Vasculitis
Arthropathy
Osteoporosis
Clubbing
Psychological
Sinusitis/polyps
How is the pancreas effected?
The CFTR mutation causes the pancreas to insufficiently produce enzymes that digest food.
What does pancreatic insufficiency result in?
Malabsorption
Abnormal stools - pale, offensive, float
Failure to thrive (grow)
How many classes of CF disease are there?
6 classes
1-3 = severe disease
4-6 = milder disease
How many levels of pancreatic function are there in CF patients and what are they?
6
1-3 = pancreatic insufficient
4-6 = some pancreatic function
What recurrent chest infections are more likely?
Pneumonia
Bronchiectasis
Abscess
What happens in bronchiectasis?
Airways become dilated and thickened
- become stiff and cant clear mucous
Mucous then becomes infected and impairs O2 exchange.
Why does pulmonary infection occur?
The CFRT abnormality causes:
- Abnormal electrolyte transport across cell membrane.
- Dehydration of airway surface layer (water later which allows mucous to slide easily up airway to be coughed up)
- Decreased mucociliary clearance
- Mucous sticks to mucosal surface of causes shearing damage
- Increased bacterial adherence
- Decreases bacterial killing
- Result = more prone to chest infections
What is the circle of events leading to recurrent chest infections in those with CF?
Bacterial colonisation
»> Inflammation, mucus plugging, airway ulceration, airway damage
»> Bronchiectasis
»> Decreased mucocillary clearance, increased bacterial adherence, decreased endocytosis of bacteria
»> Bacterial colonisation
What occurs in progressive respiratory decline?
Progressive bronchiectasis = chronic sputum production
Recurrent respiratory tract infections
Progressive airflow obstruction
Respiratory failure
What is progressive airflow obstruction?
Increasing exertional dyspnoea
Survival is related to FEV1
Multiple drugs
What is the difference between type 1 and type 2 respiratory failure?
Type 1 = Decreased PaO2
Type 2 = Decreased PaO2 and increased PaCO2
How is respiratory failure treated?
Oxygen
Nocturnal NIV
Lung transplant in some
What does a CXR look like in a CF patient?
Lungs aren’t clear
Fluffy/marshmallowy patches
What does a CT scan look like in a CF patient?
Tramlines = thickened dilated airways that cant clear mucous
Signet ring = cross section of a tramline
Mucous plugging
Consolidation (infection)
What is a peripheral sign of CF and why does it occur?
Finger clubbing
- Result of low O2 in blood
- Can be familial
What are the different types of diabetes and which is most common in CF patients?
Type 1 = No insulin is made
Type 2 = Not enough insulin from pancreas or insulin is not working properly
CF = Type 2
What are some issues specific to CF diabetes?
Compliance with diet
- Need high calorie diet unlike non-CF diabetics
Insulin is of benefit
How is osteoporosis related to CF?
Bone mineral density falls in patients with CF
- Slower gain and a faster loss
What are the effects of osteoporosis in CF?
Increased risk of fractures
May exclude lung transplant
- After transplant youre given a high dose of steroids which further thin your bones
What are some treatments for osteoporosis?
Bone protection drugs
Weight baring exercise
How does pneumothorax relate to CF?
Affects 3-4% of CF patients during their lifetime
- Greater occurrence in older more severe obstructive lung disease
Why does haemoptysis occur in CF?
Due to bronchial wall destruction
What would major haemoptysis look like?
Large amount of blood over a short period of time
May be preceded by gurgling in chest
How is a major haemoptysis treated?
Admit to hospital, resuscitate
May need bronchial angiogram and embolization (look for source of bleeding and block it off)
What are some risk factors for haemoptysis?
Severity of CF
High number of exacerbations
Fungal lung infections
Liver disease, vit K deficiency or on anticoagulant (all can thin blood)
Name some people involved in the MDT care of a CF patient?
Physician
Nurse specialist
Physiotherapist
Dietician
Psychologist
Pharmacist
Lung function physiologist
Microbiologist
Gastroenterologist
Diabetes
Primary care
How do you treat pancreatic insufficiency in CF?
Replace enzymes with Creon capsules
- Have to take 40/50 a day
Diet
- High energy plus high calorie supplement drinks
- Not low fat
Nutritional supplements
- Fat-soluble vitamin and mineral supplements
What different aspects of CF are treated?
Mucous obstruction inflammation
Infection
Increased inflammation
Fibrosis/scarring/bronchiectasis
How is mucous obstruction inflammation treated?
Airway clearance via physiotherapy
Mucolytics
- Make mucous thinner and easier to cough up
- Nebulised hypertonic saline/pulmosine
- Inhaled broncho Tol
Bronchodilators
- Inhalers e.g. salbutamol
How do you treat infections in CF?
Antibiotics
How do you treat increased inflammation in CF?
Azithromycin
- Can be used at low dose long term
- Reduces the number of infective exacerbations of CF
How do you treat fibrosis/scarring/bronchiectasis in CF?
Supportive treatment and management of symptoms
- Oxygen
- Home ventilation NIV
- Psychological support
- benefits/social issues
What is the social, educational and economic impact on children and family of CF?
Barriers to making friends
- Cough
- Missing school
- Different dietary requirements
- Taking drugs
Increased anxiety/depression
Low adherence to time-consuming treatments
Siblings
Increased cost to the family
- Time off work/hospital attendances
- Financial costs
What is the social, educational and economic impact on adults with CF?
Transition from child care team to adult
Restriction on careers and hobbies
Transport costs
Large number of drugs - compliance
Missing work
Cross infection
Co-morbitities
Psychological
- Aware of prognosis
- Promise (and cost) of new drugs
- Media/social media pressure and misinformation
What is the drug burden of a CF patient like?
Very high
- Roughly 37 types of drugs
- 30-40 capsules of Creon a day
- Nebulising treatment; 30min-1hr, done more than once a day
- Airway clearance; 15-20mins done 2/3 times a day
What are the indications a patient needs a transplant?
Rapidly deteriorating lung function
FEV1 <30% predicted
Life threatening exacerbations
Estimated survival <2years
What is the role of a lung transplant in CF patients?
A measure to prolong survival and improve quality of life (not a miracle cure)
What are some factors that would prevent a patient receiving a lung transplant?
Other organ failure
Malignancy within past 5 years
Significant peripheral vascular disease
Drug, nicotine, alcohol dependency
Active systemic infection
Microbiological issue
What factors would you have to use clinical judgement on when deciding whether to give a lung transplant or not?
Other organ dysfunction
Non-compliance
Steroids >20mg daily
Absence of recognised social support
Osteoporosis
Low or high BMI
Surgical risks (previous thoracic surgery)
Psychological instability
How can type of bacteria affect median survival?
If colonised = median survival falls
If not colonised = median survival is around 40
Why has median survival for CF improved?
CF centres
MDT
Physiotherapy
Nutrition/enzymes
Antibiotics
Aggressive approaches
Annual flu/pneumococcal vaccine
What can be done to improve the quality of life of a patient with CF?
Oxygen and NIV
Exercise
Support (physical, mental, social, financial, alternative therapies)
Advanced care plans
DNAR discussions
