Bronchiectasis, CF, Asthma, COPD Flashcards
Pathology in bronchiectasis
Chronic infection of the bronchi and bronchioles leading to permanent dilatation of these airways.
Main organisms: H. influenzae; Strep. pneumoniae; Staph. aureus; Pseudomonas aeruginosa.
Causes of bronhciectasis
Congenital: cystic fibrosis (cf); Young’s syndrome; primary ciliary dyskinesia; Kartagener’s syndrome
Post-infection: measles; pertussis; bronchiolitis; pneumonia; tb; hiv.
Other: Bronchial obstruction (tumour, foreign body); allergic bronchopulmonary aspergillosis; hypogammaglobulinaemia; rheumatoid arthritis; ulcerative colitis; idiopathic.
Sx of Bronchiectasis
Symptoms: persistent cough; copious purulent sputum; intermittent haemoptysis.
Signs: finger clubbing; coarse inspiratory crepitations; wheeze (asthma, copd, abpa).
Complications: pneumonia, pleural effusion; pneumothorax; haemoptysis; cerebral abscess; amyloidosis.
Investigations for bronchiectasis
Sputum culture.
CXR: cystic shadows, thickened bronchial walls (tramline and ring shadows);
HRCT chest: to assess extent and distribution of disease.
Spirometry often shows an obstructive pattern; reversibility should be assessed.
Bronchoscopy to locate site of haemoptysis or exclude obstruction.
Other tests: serum immunoglobulins;
CF sweat test; Aspergillus precipitins or skin-prick test.
Mx for bronchiectasis
• Postural drainage should be performed twice daily. Chest physiotherapy may aid sputum expectoration and mucous drainage. • Antibiotics should be prescribed according to bacterial sensitivities. Patients known to culture Pseudomonas will require either oral ciprofloxacin or iv antibiotics. • Bronchodilators (eg nebulized salbutamol) may be useful in patients with asthma, copd, cf, abpa ([link]). • Corticosteroids (eg prednisolone) for abpa. • Surgery may be indicated in localized disease or to control severe haemoptysis.
Cystic FIbrosis
Epidemiolgy
Mutation
Pathology
One of the commonest life-threatening autosomal recessive conditions (1 : 2000 live births) affecting Caucasians. Caused by mutations in the CF transmembrane conductance regulator (CFTR) gene on chromosome 7 (>800 mutations have now been identified).
This is a Cl- channel, and the defect leads to a combination of defective chloride secretion and increased sodium absorption across airway epithelium.
CLinical features of Cystis Fibrosis
Neonate:
Failure to thrive; meconium ileus; rectal prolapse.
Children and young adults:
Respiratory: cough; wheeze; recurrent infections; bronchiectasis; pneumothorax; haemoptysis; respiratory failure; cor pulmonale.
Gastrointestinal: pancreatic insufficiency (diabetes mellitus, steatorrhoea); distal intestinal obstruction syndrome (meconium ileus equivalent); gallstones; cirrhosis.
Other: male infertility; osteoporosis; arthritis; vasculitis; nasal polyps; sinusitis; and hypertrophic pulmonary osteoarthropathy (hpoa).
Signs: cyanosis; finger clubbing; bilateral coarse crackles.
Diagnosis and tests for CF
Sweat test: sweat sodium and chloride >60mmol/L; chloride usually > sodium.
Genetics: screening for known common cf mutations should be considered. Faecal elastase is a simple and useful screening test for exocrine pancreatic dysfunction.
Tests
Blood: fbc, u&e, lft; clotting; vitamin a, d, e levels; annual glucose tolerance test ([link]).
Bacteriology: cough swab, sputum culture.
Radiology: cxr; hyperinflation; bronchiectasis.
Abdominal ultrasound: fatty liver; cirrhosis; chronic pancreatitis;
Spirometry: obstructive defect.
Aspergillus serology/skin test (20% develop abpa, [link]).
Biochemistry: faecal fat analysis.
Management for CF
Patients with cystic fibrosis are best managed by a multidisciplinary team, eg physician, gp, physiotherapist, specialist nurse, and dietician with attention to psychosocial as well as physical well-being. Gene therapy (transfer of cftr gene using liposome or adenovirus vectors) is not yet possible.
Chest:
Physiotherapy regularly (postural drainage, active cycle breathing techniques or forced expiratory techniques). Antibiotics are given for acute infective exacerbations and prophylactically (po or nebulized). Mucolytics may be useful (eg dnase, ie Dornase alfa, 2.5mg daily nebulized, ohcs p163). Bronchodilators.
Gastrointestinal:
Pancreatic enzyme replacement; fat soluble vitamin supplements (a, d, e, k); ursodeoxycholic acid for impaired liver function; cirrhosis may require liver transplantation.
Other:
Treatment of cf-related diabetes; screening for and treatment of osteoporosis; treatment of arthritis, sinusitis, and vasculitis; fertility and genetic counselling.
Advanced lung disease:
Oxygen, diuretics (cor pulmonale); non-invasive ventilation; lung or heart/lung transplantation.
Prognosis:
Median survival is now over 30yrs.
Ways in which fungi affects the lungs??
_ 1 Asthma:_ Type I hypersensitivity (atopic) reaction to fungal spores, [link].
2 Allergic bronchopulmonary aspergillosis (abpa): This results from a type I and III hypersensitivity reaction to Aspergillus fumigatus. Early on, the allergic response causes bronchoconstriction, but as the inflammation persists, permanent damage occurs, causing bronchiectasis. Symptoms: wheeze, cough, sputum (plugs of mucus containing fungal hyphae,), dyspnoea, and ‘recurrent pneumonia’. Investigations: CXR (transient segmental collapse or consolidation, bronchiectasis); Aspergillus in sputum; positive Aspergillus skin test and/or Aspergillus-specific IgE rast (radioallergosorbent test); positive serum precipitins; eosinophilia; raised serum IgE. Treatment: prednisolone 30–40mg/24h po for acute attacks; maintenance dose 5–10mg/d. Sometimes itraconazole is used in combination with corticosteroids. Bronchodilators for asthma. Sometimes bronchoscopic aspiration of mucous plugs is needed.
- _ 3 Aspergilloma (mycetoma):_* A fungus ball within a pre-existing cavity (often caused by tb or sarcoidosis). It is usually asymptomatic but may cause cough, haemoptysis (may be torrential), lethargy ± weight loss. Investigations: CXR (round opacity within a cavity, usually apical); sputum culture; strongly positive serum precipitins; Aspergillus skin test (30% +ve). Treatment (only if symptomatic). Consider surgical excision for solitary symptomatic lesions or severe haemoptysis. Oral itraconazole and other antifungals have been tried with limited success. Local instillation of amphotericin paste under ct guidance yields partial success in carefully selected patients, eg in massive haemoptysis.
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_ 4 Invasive aspergillosis:_* Risk factors: immunocompromise, eg hiv, leukaemia, burns, Wegener’s, and SLE, or after broad-spectrum antibiotic therapy. Investigations: sputum culture; bal; biopsy; serum precipitins; cxr (consolidation, abscess). Early chest ct and serial serum measurements of galactomannan (an Aspergillus antigen) may be helpful. Diagnosis may only be made at lung biopsy or autopsy. Treatment: Voriconazole is superior to iv amphotericin.Alternatives: iv miconazole or ketoconazole (less effective). Prognosis: 30% mortality.
- 5 Extrinsic allergic alveolitis (eaa)* may be caused by sensitivity to Aspergillus clavatus (‘malt worker’s lung’). Clinical features and treatment are as for other causes of EAA. Diagnosis is based on a history of exposure and presence of serum precipitins to A. clavatus. Pulmonary fibrosis may occur if untreated.
ASTHMA
descritpion and brief pathology
Asthma affects 5–8% of the population. It is characterized by recurrent episodes of dyspnoea, cough, and wheeze caused by reversible airways obstruction. Three factors contribute to airway narrowing: bronchial muscle contraction, triggered by a variety of stimuli; mucosal swelling/inflammation, caused by mast cell and basophil degranulation resulting in the release of inflammatory mediators; increased mucus production.
Symptoms and precipitants
Intermittent dyspnoea, wheeze, cough (often nocturnal) and sputum. Ask specifically about:
Precipitants:
Cold air, exercise, emotion, allergens (house dust mite, pollen, fur), infection, smoking and passive smoking; pollution, nsaids, β-blockers,
SIGNS of asthma
attacks
Tachypnoea; audible wheeze; hyperinflated chest; hyperresonant percussion note; diminished air entry; widespread, polyphonic wheeze.
Severe attack: inability to complete sentences; pulse >110bpm; respiratory rate >25/min; pef 33–50% of predicted.
Life-threatening attack: silent chest; cyanosis; bradycardia; exhaustion; pef <33% of predicted; confusion; feeble respiratory effort.
Tests to be performerd in acute attack
Acute attack: PEF, sputum culture, fbc, u&e, CRP, blood cultures. ABG analysis usually shows a normal or slightly reduced P aO2 and low P aCO2 (hyperventilation). If P aO2 normal but the patient is hyperventilating, watch carefully and repeat the abg a little later.
If P aCO2 is raised, transfer to high-dependency unit or ITU for ventilation, as this signifies failing respiratory effort. cxr (to exclude infection or pneumothorax).
Chronic asthma: pef monitoring : a diurnal variation of >20% on ≥3d a wk for 2wks.
Spirometry: obstructive defect (↓fev 1/fvc, ↑rv ); usually ≥15% improvement in fev 1 following β2 agonists or steroid trial. cxr: hyperinflation. Skin-prick tests may help to identify allergens. Histamine or methacholine challenge. Aspergillus serology.
DIfferentials associated with asthma presentation
Pulmonary oedema (‘cardiac asthma’); copd (may co-exist); large airway obstruction (eg foreign body, tumour); svc obstruction (wheeze/dyspnoea not episodic); pneumothorax; pe; bronchiectasis; obliterative bronchiolitis (suspect in elderly).
BTS guidelines for asthma management
Start at the step most appropriate to severity; moving up if needed, or down if control is good for >3 months. Rescue courses of prednisolone may be used at any time.
Step 1
Occasional short-acting inhaled β2-agonist PRN. If used more than once daily, or night-time symptoms, go to Step 2.
Step 2
Add standard-dose inhaled steroid, eg beclometasone 100–400μg/12h, or start at the dose appropriate for disease severity, and titrate as required.
Step 3
Add long-acting β2-agonist (eg salmeterol 50μg/12h). If benefit—but still inadequate control—continue and ↑dose of beclometasone to 400μg/12h. If no effect of long acting β2-agonist stop it. Review diagnosis. Leukotriene receptor antagonist or oral theophylline may be tried.
Step 4
Consider trials of: beclometasone up to 1000μg/12h; modified-release oral theophylline; modified-release oral β2-agonist; oral leukotriene receptor antagonist (see below), in conjunction with previous therapy. Modified-release β2 agonist tablets.
Step 5
Add regular oral prednisolone (1 dose daily, at the lowest possible dose). Refer to asthma clinic.
Drugs for asthma
β2-adrenoceptor agonists
relax bronchial smooth muscle (↑cAMP), acting within minutes. Salbutamol is best given by inhalation (aerosol, powder, nebulizer), but may also be given po or iv. SE: tachyarrhythmias, ↓K+, tremor, anxiety.
Long-acting inhaled β2-agonist (eg salmeterol, formoterol) can help nocturnal symptoms and reduce morning dips. They may be an alternative to ↑steroid dose when symptoms are uncontrolled; doubts remain over whether they are associated with an increase in adverse events SE: as salbutamol, paradoxical bronchospasm.
Corticosteroids
are best inhaled to minimize systemic effects, eg beclometasone via spacer (or powder), but may be given po or iv. They act over days to ↓bronchial mucosal inflammation. Rinse mouth after inhaled steroids to prevent oral candidiasis. Oral steroids are used acutely (high-dose, short courses, eg prednisolone 40mg/24h po for 7d) and longer term in lower dose (eg 5–10mg/24h) if control is not optimal on inhalers. Warn about ses: [link].
Aminophylline
(metabolized to theophylline) may act by inhibiting phosphodiesterase, thus ↓bronchoconstriction by ↑cAMP levels. Try as prophylaxis, at night, po, to prevent morning dipping. Stick with one brand name (bioavailability variable). It is also useful as an adjunct if inhaled therapy is inadequate. In acute severe asthma, it may be given ivi. It has a narrow therapeutic ratio, causing arrhythmias, gi upset, and fits in the toxic range. Check theophylline levels ([link]), and do ecg monitoring and check plasma levels after 24h if iv therapy is used.
Anticholinergics
(eg ipratropium, tiotropium) may ↓muscle spasm synergistically with β2-agonists but are not recommended in current guidelines for asthma. They may be of more benefit in copd.
Cromoglicate
May be used as prophylaxis in mild and exercise-induced asthma (always inhaled), especially in children. It may precipitate asthma.
Leukotriene receptor antagonists
(eg montelukast, zafirlukast) block the effects of cysteinyl leukotrienes in the airways by antagonising the CystLT1 receptor.
Anti-IgE monoclonal antibody
OmalizumabChest medicine42 may be of use in highly selected patients with persistent allergic asthma. Given as a subcutaneous injection every two to four weeks depending on dose. Specialists only.
standard doses for corticosteroids for asthma
Standard-dose inhaled corticosteroids
Beclometasone dipropionate or budesonide 100–400 micrograms twice dailyFluticasone propionate 50–200 micrograms twice daily;Mometasone furoate 400 micrograms as a single dose in the evening or in 2 divided doses
Acute asthma exacerbation treatment
Severe acute asthma can be fatal and must be treated promptly. All patients with severe acute asthma should be given high-flow oxygen (if available) and an inhaled short-acting beta2 agonist via a large-volume spacer or nebuliser; give 2–10 puffs of salbutamol 100 micrograms/metered inhalation, each puff inhaled separately via a large-volume spacer, and repeat at 10–20 minute intervals or as necessary. If there are life-threatening features, give salbutamol or terbutaline via an oxygen-driven nebuliser every 20–30 minutes or as necessary. In all cases, a systemic corticosteroid (section 6.3.2) should be given. For adults, give prednisolone 40–50 mg by mouth for at least 5 days, or intravenous hydrocortisone (preferably as sodium succinate) 100 mg every 6 hours until conversion to oral prednisolone is possible.
SUMMARY
Oxygen
- Nebulized salbutamol and ipratropium bromide
- Steroids: iv hydrocortisone, followed by oral prednisolone
- Monitor PEFR and ABG
- If no improvement: iv magnesium sulphate. Consider iv aminophylline infusion or iv salbutamol.
- Summon anaesthetic help if patient is getting exhausted (PCO2 increasing)
- Monitor serum K+ daily and supplement as necessary.
- Treat any underlying cause (e.g. infection, pneumothorax). Give antibiotics if there is evidence of chest infection (purulent sputum, abnormal CXR, raised WCC, fever).
INDICATIONS FOR ITU ADMISSION
- Hypoxia (PaO2 <8kPa (60mmHg) despite FiO2 of 60%
- Rising PaCO2 or PaCO2 >6kPa (45mmHg)
- Exhaustion, drowsiness, or coma
- Respiratory arrest
- Failure to improve despite adequate therapy.
