Asthma Flashcards
What is asthma?
a disease characterized by recurrent attacks of breathlessness and wheezing which vary in severity and frequency from person to person
- asthma affects all age groups but usually starts in childhood
What causes asthma?
due to inflammation of the air passages in the lungs and affects the sensitivity of the nerve endings in the airways so they become easily irritated
- in an attack the lining of the passages swell causing the airways to narrow and reducing the flow of air in and out of the lungs
Epidemiology?
- Affects around 300 million people worldwide
- Half of patients with childhood asthma will not continue to have symptoms in adulthood (”grow out of it”)
- Prevalence in Africa: 13% (and rising), Malawi: unknown
- But according to WHO: 3 people die each day in Malawi from asthma
> Underdiagnosed and underrecognized.
> Most recorded deaths are in adults >45 years
Pathogenesis?
- Airflow limitation/obstruction
- Airway hyperresponsiveness
- Inflammation of the bronchi
- Airway wall remodelling; &
epithelial damage
Pathogenesis of airflow obstruction in acute asthma?
- Bronchoconstriction
- Airway edema
- Mucous plugs (take weeks to resolve)
- Hyperinflation
Airflow obstrction in chronic asthma?
- Chronic mucous plugging, & long standing inflammation → airway remodeling with excess narrowing
- Epithelial damage → more susceptible to infection and allergens.
Airway hyperresponsiveness?
Airway response to exogenous and endogenous stimuli
1. Exogenous are direct stimulation (allergens etc)
2. Endogenous include activator substances secreted from mast cells and sensory neurons
Asthmatic attack triggers?
- exercise
- pollen
- bugs in the home
- chemical fumes
- cold air
- fungus spores
- dust
- smoke
- strong odors
- pollution
- anger/stress
- pets
- medication e.g. NSAIDS, beta blockers
- viral infections
- GERD
Etiology of asthma?
- Extrinsic (atopy) vs intrinsic (no identified causative agent).
- Atopy
- asthma, eczema, allergy
Ig E-antibody production is influenced by genetic and environmental factors. - Hygiene theory
- exposure to bacteria/viruses/fungi in childhood directs the immune and inflammatory response away from the allergic pathways (uncertain)
Symptoms of asthma?
classic triad
1. breathlessness
2. cough
3. wheeze (sometimes only nightly cough)
Important history questions?
- Symptoms & Severity
- Previous hospitalizations (frequency, last)
- Medication history
- What do they take? How is adherence?
- Exposures > allergens (“triggers”), smoking, method of cooking
- Clues to other possible etiologies
- Infectious symptoms, TB contacts, weight loss, etc.
Physical exam in asthma?
- VITALS (count the RR)
- Wheezing
- Differential diagnosis, target your physical exam to exclude other pathologies
- Inspiratory or expiratory? - Signs of atopy
Note: Approach depends on the severity (ABCD in severe exacerbation)
Ddx for wheezing?
- heart failure
- vocal cord dysfunction
- viral infections in children
- tracheal lesions
- foreign body aspiration
Note:
- In mild asthma may only be expiratory
- in more moderate severe inspiratory and expiratory
- In very severe, lungs may be too clamped down to have any wheezing
Signs of atopy?
- Allergic shiners
- transverse crease on nose from allergic rhinitis
- atopic dermatitis (eczema; 25% has Dennie Morgan lines)
- Nasal crease: caused by re[eated nose rubbing (allergic rhinitis)
Clinical diagnosis of asthma?
- history taking
- physical examination
- trial of bronchodilators
Diagnosing asthma with a trial of bronchodilators?
- Peakflow meter
- Measure FEV1 (forced expiratory volume in the first second)
- FEV1 reduces in case of obstructed airway, but in case of Asthma is mostly reversible after bronchodilators - Spirometry;
- FEV1/FVC before and after bronchodilators
- improvement of FEV1 >12% and >200ml after bronchodilator
Ddx of acute dyspnea and their exam findings?
- Acute heart failure > bilateral basal crepitations
- Pneumothorax > diminished breath sounds
- Pulmonary embolism > normal chest auscultation
- Upper airway obstruction > wheezing
- Massive pleural effusion > absent breath sounds
- Severe pneumonia > crepitation
Asthma clinical clues?
- onset before 20 years
- associated hay fever, eczema, allergic conjuctivitis, allergies
- intermittent symptoms with normal breathing in between
- symptoms worse at night, early morning, with cold or stress
- patient or family have a history of asthma
COPD clinical clues?
- onset after 40 years age
- symptoms are persistent and worsen over time
- cough with sputum starts long before difficult breathing
- patient is or was a heavy smoker
- previous doctor diagnosis of COPD
Diagnosis of severe/life threatening asthma?
- Silent chest
- Central cyanosis
- Tachypnea (>30 RR), exhaustion, inability to complete sentences
- Persistent tachycardia (110 bpm), bradycardia, hypotension, pulsus paradoxes
- Use of accessory breathing muscles
- Confusion, agitation, coma
- Peak flow < 33%
Mangement of severe asthma attack?
- O2 (until sat > 95%)
- Salbutamol 5mg (<4 yrs 2,5mg) + Ipratropium 0,5mg via nebulizer (if not available via spacer)
- Start with 3 back-to-back.
- Repeat every 20 min (1st hour)
- Observer 24h after symptoms have relieved
- Discharge on 2-4 puff every 3-4 h with tapering schedule - Prednisolone 40 mg p.o. OD for 3 days (paeds 1-2mg/kg)
OR Hydrocortisone 100mg i.v. OD (<5 yrs 50mg)
OR dexamethasone 0,6 mg/kg OD (max 10mg). - No improvement: magnesium sulphate 40 mg/kg i.v. (diluted to at least 10%) over 20 min
OR Aminophylline 5mg/kg i.v. (diluted, max 25 mg/ml) (max 300mg) over 20 min
Who not to give aminophylline to?
patients with recent hx of MI or tachy-arythmia
- because it cases QT prolongation
Consequences of too quick of an infusion of aminophylline?
- seizures
- severe vomiting
- tachycardia/arrythmia.
Clinical signs of mild asthma attack?
wheeze, no respiratory distress, feeding well, spO2 >92% (no moderate signs)
