Respiratory Flashcards
(227 cards)
Define aspergillus lung disease
Lung disease associated with Aspergillus fungal infection
Aspergillus infection is usually caused by Aspergillus fumigatus
How can aspergillus affect the lung
- Asthma (atopic)
- Allergic bronchopulmonary aspergillosis
- Aspergilloma (mycetoma)
- Invasive aspergillosis
- Extrinsic allergic alveolitis
Risk factors for aspergillus
ABPA: asthmatics (1-2%) and CF (25%)
Invasive aspergillosis: immunocompromised (see pg. 168)
Brief info about how each type of aspergillus lung disease is caused
- Asthma
- type 1 hypersensitivity rxn to fungal
spores - ABPA
- type 1 and type 3 hypersensitivity rxn to aspergillus fumigatus (early on bronchoconstriction, later bronchiectasis) - Aspergillioma
- Fungus ball within pre-existing cavity (often due to TB/sarcoidosis). Usually asymptomatic. - Invasive aspergillosis
-Invasion of Aspergillus into lung tissue and fungal dissemination
This occurs in immunosuppressed patients (e.g. neutropenia, steroids, AIDS) - Extrinsic allergic alveolitis
- May be sensitivity to aspergillus clavatus (malt workers lung)
Epidemiology of aspergillus lung disease
UNCOMMON
Mainly occurs in the ELDERLY and IMMUNOCOMPROMISED
Presenting symptoms of aspergillus lung disease
ABPA:
-Difficult to control asthma; wheeze; cough; sputum; recurrent pneumonia
Aspergilloma:
-Usually asymptomatic
-Cough, haemoptysis (can be torrential)
lethargy, weight loss
Invasive aspergillosis:
-Dyspnoea, rapid deterioration, septic picture
Signs of aspergillus lung disease
Tracheal deviation (only with very large aspergillomas)
Dullness in affected lung
Reduced breath sounds
Wheeze (in ABPA)
Halo sign (invasive aspergillosis… nodules surrounded by ground-glass appearance)
Cyanosis (possible in invasive aspergillosis)
Investigations for aspergillus lung disease
ABPA:
- CXR
- Aspergillus in sputum
- Aspergillus skin test and/or Aspergillus-specific IgE RAST
- Eosinophilia
- Raised serum IgE
- Positive preciptins
Aspergilloma:
- CXR (rounded opacity within cavity, usually apical… crescent of air)
- Sputum
- strongly positive serum preciptins
- Aspergillus skin test
Invasive aspergillosis
-Aspergillus is detected in cultures or by histological
examination
-Bronchoalveolar lavage fluid or sputum may be used
diagnostically
Pathophysiology of asthma
Asthma risk factors
Inflammaotry disease driven by Th2 cells. 3 processes:
1) Bronchial hyerresponsiveness
2) Bronchial inflammation (symptoms primarily due to inflammation of terminal bronchioles, lined with SM but not cartilage)
3) Endobronchial obstruction
Early phase (up to 1hr): xposure toinhaledallergens inapresensitized individual results in cross-linking of IgE antibodies on the mast cell surface and release of histamine, prostaglandin D2, leukotrienes and TNF-a. These mediators induce smooth muscle contraction (bronchoconstriction), mucous hypersecretion, oedema and airway obstruction.
Late phase (after 6–12h): Recruitment of eosinophils, basophils, neutrophil and Th2 lymphocytes and their products results in perpetuation of the inflammation and bronchial hyper-responsiveness.
Airway remodelling
GENETIC:
Atopy (=tendency for T lymphocytes to drive production of IgE on exposure to allergens)
Family history
ENVIRONMENTAL: House dust mites Pollen Pets Cigarette smoke Viral respiratory tract infections Aspergillus fumigatus spores Occupational allergens
Epidemiology of asthma
Affects 10% of children
Affects 5% of adults
Prevalence appears to be increasing
Asthma presenting symptoms
Episodic history
Wheeze
Breathlessness
Cough (worse in the morning and at night)
IMPORTANT: ask about previous hospitalisation due to acute attacks - this gives an
indication of the severity of the asthma
Precipitating factors for asthma
Cold Viral infection Drugs (e.g. beta-blockers, NSAIDs) Exercise Emotions Check for history of atopic disease (e.g. allergic rhinitis, urticaria, eczema)
Recognise the signs of asthma on physical examination
What is severe attach vs life threatening attack
What about near fatal
Tachypnoea Use of accessory muscles Prolonged expiratory phase Polyphonic wheeze Hyperinflated chest
Severe Attack: PEFR < 50% predicted Pulse > 110/min RR > 25/min Inability to complete sentences
Life-Threatening Attack: PEFR < 33% predicted Silent chest Cyanosis Bradycardia Hypotension Confusion Coma
Near fatal:
And/or requiring mechanical ventilation with raised inflation pressures
Asthma investigation
Acute setting vs diagnosis in chronic setting
1st line and second line test
If unsure of diagnosis?
If SpO2<94%?
What type of respiratory failure occurs in asthma
If you suspect allergic asthma?
Acute:
Peak flow, pulse oximetry, ABG, CXR, FBC (inceased WCC if infective exaerbation), CRP, U&Es, blood and sputum cultures
Chronic:
Diagnosis:
1) Spirometry + bronchodilator test is 1st line for confirming diagnosis.
-Signs of obstructive lung disease:
-FEV1/FVC ratio (<0.8 what is expected. FEV1 after bronchodilator should show at least 200mL and 12% IMPROVEMENT)
2) Methacholine challenge test is second line if pulmonary function testing is non-diagnostic:
- A >20% drop in FEV1 after administration of methacholine is diagnostic
*20% diurnal variation in PEFR on at least 3 days for a number of weeks can also diagnose asthma. An improvement by 20% of PEFR in response to a couple of weeks of asthma treatment is also diagnostic
3) Chest x-ray to exclude other diagnoses like pnuemonia and pneumothorax.
-Signs of pulmonary hyperinflation in cases of severe asthma
Low, flattened diaphragm
Wide intercostal spaces
Barrel chest
Monitoring: PEFR. Often a diurnal variation with a morning ‘dip’.
OTHER LAB
- IF SpO2 is less than 94%, do ABG.
- Initially there is reduced pCO2, raised pH, reduced pO2 so a T1RF
- Ultimately, there’s severe respiratory distress, leading to rising pCO2, low pH, very reduced o2 and T2RF.
Patients with acute asthma exacerbations initially have reduced PCO2 and respiratory alkalosis (raised pH) due to tachypnea. Rising PCO2 is a sign of respiratory fatigue and impending respiratory failure
Allergic asthma:
- Ab testing (total IgE)
- FBC may show eosinohilia
- Skin allergy tests
- Sputum sample (curschmann spirals, charcot-leyden crystals, and creola bodies)
Chronic
Peak flow monitoring - often shows diurnal variation with a dip in the morning Pulmonary function test
Bloods - check:
Eosinophilia
IgE level
Aspergillus antibody titres
Skin prick tests - helps identify allergens
Asthma management (chronic)
STEP 1
Inhaled short-acting beta-2 agonist used as needed
If needed > 1/day then move onto step 2
STEP 2
Step 1 + regular inhaled low-dose steroids e.g. beclamethasone (400 mcg/day)
STEP 3
Step 2 + inhaled long-acting beta-2 agonist (LABA)
If inadequate control with LABA, increase steroid dose (800 mcg/day)
If no response to LABA, stop LABA and increase steroid dose (800 mcg/day)
STEP 4
Increase inhaled steroid dose (2000 mcg/day)
Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2
agonist tablet)
STEP 5
Add regular oral steroids Maintain high-dose oral steroids
Refer to specialist care
Asthma management (acute)
Resuscitate, monitor o2 sats, ABG and PEFR
High-flow oxygen
Salbutamol nebulizer (5 mg, initially continuously, then 2-4 hourly) Ipratropium bromide (0.5 mg QDS)
Steroid therapy (100-200 mg IV hydrocortisone + 40 mg oral prednisolone for 5-7 days)
If no improvement –> IV magnesium sulphate. Consider IV aminophylline infusion
Consider IV salbutamol.
If PCO2 begins to increase, call anaesthetic help.
Ventilation may be needed on severe attacks.
Why is a normal pCO2 bad in an acute asthma episode
This is because during an asthma attack they should be hyperventilating and blowing off their CO2, so PCO2 should be low
A normal PCO2 suggests that the patient is fatiguing
What do you need to look out for with electrolytes during acute asthma treatment
Monitor electrolytes closely because bronchodilators and aminophylline causes a drop in K+
Complications of asthma
What complication of acute asthma treatment do you want to be careful about
Growth retardation Chest wall deformity (e.g. pigeon chest) Recurrent infections Pneumothorax Respiratory failure Death
Bronchodilators and aminophylline reduce potassium, so watch electrolytes closely for hypokalaemia
Define TB
Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person.
It mainly affects the lungs, but it can affect any part of the body, including the tummy (abdomen), glands, bones and nervous system.
Explain aetiology/risk factors for TB
(-names of the species causing it
- do they need o2?
- do they replicate inside or outside cells?
- What cell types does it infect
- How fast do they grow
- Gram stain?
- What staining method is used?
- t/f all those infected with TB develop active disease
Aeritiolgy: -Caused by 4 mycobacterial species, names the Mycobacterium tuberculosis complex (MTb) •Mycobacterium tuberculosis •Mycobacterium bovis •Mycobacterium africanum •Mycobacterium microti.
- These are obligate aerobes (i.e. need o2 to respire) and facultative intracellular pathogens (capable of living and reproducing inside or outside of cells)
- Usually infect mononuclear phagocytes
- Slow growing (12-18hr)
- relatively impermeable and stain only weakly with Gram stain
- they are termed ‘acid-fast bacilli’.
- F: Only a small number of bacteria need to be inhaled for infection to develop but not all those who are infected develop active disease. The outcome of exposure is dictated by a number of factors
Risk:
-Contact w high risk groups (origination/frequent travel to high risk country)
- Immune deficiency: corticosteroids, HIV, chemotherapy, nutritional deficiency, DM, CKD, malnutrition
- Lifestyle factors: drug/alcohol, homelessness, prison inmates
- genetic susceptibility (twin studies of gene polymorphisms)
Summarise epidemiology of TB
1/3 of world population infected
Co-infection with HIV remains a problem
Presenting symptoms of TB
Productive cough,sometimes systemic symptoms (weight loss, fevers, night sweats).
Hoarse voice and severe cough if laryngeal involvement,
Pleuritic chest pain if involving pleura
Signs of TB on physical examination
Pulmonary: Abnormal breath sounds, bronchial breathing, hoarse voice,
Extrapulmonary: confusion, neurological deficit, lymphadenopathy, cutaneous lesions, Weight loss,
Lymphadenopathy usually bilateral