Respiratory Flashcards
Define asthma
Chronic inflammatory airway disease characterised by intermittent reversible airway obstruction, bronchial hyper-responsiveness and inflammation
What is the aetiology of asthma?
Multi-gene association interacting with environmental exposure
- Initial trigger leads to the release of inflammatory mediators
- Activation and migration of other inflammatory cells.
- Th2 lymphocytic response - release of interleukins, chemokines etc.
- Inflammatory cells move to the airway, causing changes in the epithelium, airway tone, hyper-secretion of mucus, mucociliary function alteration and increased smooth muscle responsiveness.
Acute: SM contraction leading to bronchoconstriction Mucus hypersecretion Oedema Airway obstruction
Chronic:
Proliferation of SM cells and fibroblasts causing airway remodelling
What are the risk factors of asthma?
Family history Atopic history - eczema, dermatitis, allergic rhinitis Obesity GORD Nasal polyposis
Exposure to allergens/precipitants: Cats Dogs Cockroaches Dust mites Fungal spores Tobacco smoke Fumes from chemicals eg bleach Pollen from trees, weeds, and grass. Viral infections - rhinovirus, influenza Bacterial infections - Mycoplasma pneumoniae, chlamydia pneumoniae Cold Exercise Extreme emotion
Summarise the epidemiology of asthma
Affects 10% of adults and 5% of children
Prevalence is increasing
Highest hospitalisation rates and asthma deaths were amongst black patients
What are the presenting symptoms of asthma?
Cough
Wheeze
SOB/dyspnoea precipitated by allergen exposure
Chest pain/tightness
Nocturnal symptoms
Worse at night
Variation in symptoms (episodic history) - sometimes fine and sometimes symptomatic
Previous hospitalisation for asthma
What are the signs on physical examination of asthma?
Nasal polyps/congestion Polyphonic high-pitched expiratory wheeze Tachypnoea Prolonged expiratory phase Hyperinflated chest Chest may be silent in severe asthma
What are the appropriate investigations for asthma?
Forced Expiratory Volume in 1 second/Forced Vital Capacity - <80% of predicted
FEV1 <80% of expected
PEFR - variation >20% over 3 days a week over several weeks. >20% increase following bronchodilator therapy
ACUTE: Peak flow Pulse oximetry ABG CXR - to exclude other diagnoses (e.g. pneumonia, pneumothorax). Normal or hyperinflated. May show signs of infection. FBC - raised WCC if infective exacerbation CRP U&Es Blood and sputum cultures
CHRONIC:
Peak flow monitoring - often shows diurnal variation with a dip in the morning
Pulmonary function test
Bloods - Eosinophilia, IgE level, Aspergillus antibody titres
Skin prick tests - identify allergens
What is the management of an acute exacerbation of asthma?
ABCDE and necessary resuscitation
Monitor O2 sats, ABG, PEFR and U&Es (K+ lowered by bronchodilators)
High-flow oxygen (get to 94-98%)
Salbutamol nebulizer (5 mg initially continuously, then 2-4 hourly)
Nebulised Ipratropium bromide (0.5 mg QDS)
Steroid therapy: 100-200 mg IV hydrocortisone. THEN, 40 mg oral prednisolone for 5-7 days
If no improvement - IV magnesium sulphate
Consider IV aminophylline infusion
Consider IV salbutamol
May need ITU and ventilation if fatiguing.
- Normal PCO2 is a BAD SIGN as they should be hyperventilating and blowing off their CO2 (PCO2 should be low)
Treat underlying cause (e.g. antibiotics if it is an infective exacerbation)
DISCHARGE when: PEF > 75% predicted Diurnal variation < 25% Inhaler technique checked Stable on discharge medication for 24 hours Patient owns a PEF meter Patient has steroid and bronchodilator therapy Arrange follow-up
What is the management of chronic asthma?
Start on the step that matches the severity of the patient’s asthma
- Inhaled short-acting beta-2 agonist used as needed eg SALBUTAMOL
If needed > 1/day then move onto step 2 - SABA + regular inhaled low-dose steroids (400mcg/day)
- SABA + low-dose steroids + inhaled long-acting beta-2 agonist
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) - Increase inhaled steroid dose (2000 mcg/day)
Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet) - Add regular oral steroids
Maintain high-dose oral steroids
Refer to specialist care
What are the possible complications of asthma?
Exacerbations Airway remodelling Oral candidiasis secondary to incorrect use of inhaled corticosteroids Growth retardation Chest wall deformity – Harrison’s sulcus Recurrent infections Pneumothorax Respiratory failure Death
What is the prognosis of asthma?
Patients with well-controlled asthma have the same life expectancy as patients without
Many children improve as they get older
Adult-onset asthma is usually chronic
Define COPD
A chronic progressive lung condition that is characterised by irreversible airflow obstruction which encompasses emphysema and chronic bronchitis.
What is emphysema and describe its aetiology?
Pathological diagnosis of permanent destructive enlargement of air spaces distal to the terminal bronchioles
Destruction and enlargement of alveoli due to elastin breakdown, causing loss of the elastic traction that keeps small airways open in expiration.
What is chronic bronchitis and describe its aetiology?
Chronic cough and sputum production on most days for at least 3 months per year over 2 consecutive years
Narrowing of the airways due to bronchiole inflammation and bronchi with mucosal oedema, mucous hypersecretion (increased goblet cell size and number) and squamous metaplasia
What are the causes/risk factors of COPD?
CIGARETTE SMOKING Advanced age White ancestry Air pollution Occupational exposure (dust, traffic fumes, sulphur dioxide) Male sex Developmentally abnormal lung Genetic disorders eg alpha-1 antitrypsin deficiency (common cause in young, non-smokers)
Summarise the epidemiology of COPD
More common in those over 65 years old
Slightly higher prevalence in men
Very common - prevalence up to 8%
What are the presenting symptoms of COPD?
Chronic cough and white frothy sputum production (often in morning) Progressively worsening SOB Fatigue Wheeze Reduced exercise tolerance History of smoking
What are the signs on physical examination of COPD?
Barrel chest Hyper-resonance on auscultation Quiet breath sounds, prolonged expiration, crepitations Wheeze Coarse crackles Tachypnoea Tchycardic Asterixis Cyanosis Clubbing Use of accessory muscles Bounding pulse
In late stages, signs of right heart failure i.e. raised JVP, ankle oedema, RV heave
What are appropriate investigations for COPD?
Spirometry - FEV1/FVC <0.7
Pulse oximetry - low O2 sats (88-90%)
CXR - hyperinflation (>6 anterior ribs visible, flat hemidiaphragms)
ECG - risk factors for COPD similar to those of IHD
Alpha-1 antitrypsin
Acute presentation:
ABG - PaCO2 >50mmHg +/- PaO2 <60mmHg suggests respiratory insufficiency
FBC - increased WCC and haematocrit, raised Hb (secondary polycythaemia)
Sputum culture
What is the management of an acute exacerbation of COPD?
Short acting bronchodilator
Systemic corticosteroid which is transferred to inhaled corticosteroid
Airway clearance techniques (respiratory physio to clear sputum)
Supplementary O2 - 24% via non-variable flow Venturi Mask (aim for 88-92% O2 sats)
Antibiotics if infectious exacerbation
Non-invasive positive pressure ventilation if respiratory insufficiency (BiPAP)
Prevent infective exacerbations: pneumococcal & influenza vaccination
What is the management of COPD?
Short or long-acting bronchodilator (SABA or LABA, anti-cholinergics eg ipratropium bromide via inhaler or nebs)
If LABAs used >2 exacerbations per year - use steroids (oral eg prednisolone or inhaled eg budesonide)
Patient education and prophylactic vaccination
Smoking cessation
Pulmonary rehabilitation
Long term O2 therapy
What are possible complications of COPD?
Cor pulmonale - R sided heart failure secondary to long-standing COPD (chronic hypoxia - pulmonary vasoconstriction - pulmonary hypertension) Recurrent pneumonia Pneumothorax Respiratory failure Anaemia Secondary polycythaemia
What is the prognosis of COPD?
Variable prognosis dependent on genetic predisposition, environmental exposure, comorbidities
High level of morbidity
Three-year survival rate 90% if <60 years old, FEV1>50% predicted
Three-year survival rate 75% if >60 years old and FEV1 40-49% predicted.
Define acute respiratory distress syndrome
Syndrome of acute and persistent lung inflammation with increased vascular permeability due to non-cardiogenic pulmonary oedema.