Asthma Flashcards
What is asthma?
- Condition of atopy characterised by chronic inflammatory airway disease
- A disease of small airways with expiratory airflow limitation
- Inflammation is usually reversible
What causes inflammation of the small airways?
- Smooth muscle constriction
- Hypertrophy
- Mucus production
What is the pathophysiology of asthma?
- Chronic inflammatory process
- Susceptibility
- Variable airflow obstruction
- Airway hyper-responsiveness
- Reversibility
What happens in asthma?
- Airway smooth muscle: hyperresponsiveness, constriction, thickening
- Sub-epithelial inflammation and fibrosis
- Mucus hypersecretion and impaired mucus clearance
- Increased eosinophils and/or neutrophils in airway lumen
What is the immediate response in asthma?
- Type 1 hypersensitivity reaction
- IgE antibodies recognise antigens
- Mast cell degranulation
- Leads to smooth muscle contraction and bronchoconstriction
What is the late phase response in asthma?
- Type 4 hypersensitivity reaction
- Chronic inflammation
- Caused by eosinophils, mast cells, lymphocytes, neutrophils
- Ultimately leads to: sub-epithelial inflammation/fibrosis, mucus hypersecretion, airway remodelling
What is the typical presentation of asthma?
- Dry cough, worse at night
- Wheeze
- Breathlessness
- Chest tightness
- Symptoms triggered by precipitating factors
- PMH of atopy
What might you find on examination of a patient with asthma?
- Wheeze (expiratory)
- Rapid respiratory rate
- Low oxygen saturations
- Use of accessory muscles
- Signs of atopy e.g. eczema
What is atopy?
- A pre-disposition to an immune response and allergy
- E.g. hay fever, eczema, asthma
What are some triggers of asthma?
- Allergens - pollen, pets
- Dust
- Cigarette smoke
- Cold weather
- Exercise
- Infection
What are the options for investigating asthma?
- Test for airway obstruction: spirometry and bronchodilator reversibility
- Test for variability: reversibility, PEF charting, challenge tests
- Test for eosinophilic inflammation or atopy: FeNO, blood eosinophils, skin-prick test, IgE
What is peak flow?
- Most common, easiest and cheapest way to investigate asthma
- Get patient to breathe as hard and fast as they can
- Based on age, height, gender
- Lower peak flow in asthmatics due to narrow airways
- Harder to breathe out (small airways collapse on expiration)
What is FEV1 in spirometry?
- Total volume of air you can breathe out in one second after maximum inspiration
What is forced vital capacity?
- Total volume of air you can exhale from maximal expiration
What is seen in spirometry in asthmatics?
- Reduced expiratory flow rate and volume
- Descent is not linear (scalloped out)
- Reversible i.e. improves after salbutamol is given
What is FeNO?
- A breathing test looking at the level of nitric oxide in a single exhaled breath
- NO is a marker for eosinophilic inflammation in the lungs
- ROS produced by eosinophils
What is a positive score for FeNO in asthmatics?
->40 ppb
What are the similarities between asthma and COPD?
- Wheeze
- Obstructive pattern
What are the differences between asthma and COPD?
- Dry cough vs productive cough
- Atopy history vs smoking history
- Children/young people vs adults
- Good reversibility vs poor reversibility
What is a non-medical treatment for asthma?
- Remove triggers
- Avoid culprit foods
- Stop smoking
- Keeping away from hair shedding pets
What is the medical treatment for asthma?
- Stepwise approach - patients can move up and down ladder to improve control as needed
- Pt moves up a step if using blue inhaler 3+ times per week
- Given preventer treatments +/- add-on therapy
What are the management options for asthma emergencies?
- Oxygen
- Nebulised salbutamol/ipratropium
- Steroids
- Magnesium infusion
- Theophylline
What investigations might you do for a patient having an asthma attack?
- Oxygen saturations
- RR
- HR
- Auscultation
- ABG
What would make you worried in a patient having an asthma attack?
- If their CO2 gets raised
- Pt is getting tired
- Silent chest
- Acidosis
