Asthma Flashcards
What is asthma and what are the characteristics
an inflammatory disease of the respiratory system characterized by 1)bronchial hyperresponsiveness, 2)episodic exacerbations (asthma attacks), 3)reversible airflow obstruction
Types of asthma according to age
Allergic (extrinsic) asthma usually develops during childhood and is triggered by allergens such as pollen, dust mites, and certain foods.
Nonallergic (environmental or intrinsic) asthma usually develops in patients over the age of forty and can have various triggers, such as cold air, medication (e.g., aspirin),
Paediatric asthma epidemiology I
Asthma is the most common chronic disease of childhood
Asthma affects 1 in 13 school-age children and is a leading cause of GP and emergency department visits, hospitalizations, and school absenteeism.
Sex: m>f below 18 reverse above 18
Risk factors for developing asthma
• Family history • History of allergic disorders -eczema • Living in an urban region • Obesity • Immaturity at birth • Frequent acute viral infections in infancy • Smoking at home • Smoker – the child • Early exposure to antibiotics • Breast feeding reduces the risk for asthma!!!
Triggering factors for asthma
Environmental allergens:
pollen, dust mites, domestic animals, mold spores
PP of asthma
3 step process
1) Bronchial hyperresponsiveness
2) Bronchial inflammation
3) Endobronchial obstruction
Allergic asthma
1) Bronchial hyperresponsiveness
IgE-mediated type 1 hypersensitivity to a specific allergen; characterized by mast cell degranulation and release of histamine after a prior phase of sensitization
2) Terminal Bronchial inflammation
- consists of smooth muscle but no cartilage unlike in larger airways
- hypersensitivity Rxn mediates inflammation at the terminal bronchial causing oedema & Sm contrxn
3) Endobronchial obstruction
- oedema And spasm cause bronchiolar collapse
- further perpetuated by increased mucus production
Chronic / persistent sx of asthma
Mild to moderate symptoms Persistent, dry cough worsen: -night, with exercise, trigger exposure wheezes at the end of respiration !! Other atopic diseases! Atopic dermatitis/ rhinitis Dyspnea Chest tightness
Severe symptoms
Severe dyspnea
Pulsus paradoxus
Hypoxemia
Lab tests for asthma
ABG: must be done performed if oxygen saturation (SpO2) is < 94%
Findings
↓ pO2 = type 1 respiratory failure
↓ pO2 and ↑ pCO2 = type 2 respiratory failure
In allergic asthma
ASTHMA ATTACK RF: ↓ PCO2 and ↑ pH due to tachypnea. If these values begin to normalize, it is a sign of respiratory fatigue and impending respiratory failure!
Antibody testing
total IgE (increased)
allergen-specific IgE (increased)
CBC: possibly eosinophilia
Skin allergy tests:
skin prick testing / intradermal skin testing
asthma triggered by infection
elevated inflammatory markers
Sputum sample
What do sputum samples show on
Curschmann spirals :Whorled mucous plugs in sputum that are formed by shed bronchial epithelium
Charcot-Leyden crystals: histopathologic finding in patients with eosinophilic inflammation and/or proliferation (e.g., asthma, parasitic infections).
Creola bodies: desquamated epithelial cells often found in the sputum of asthma patients
Lung evaluation in asthma
Spirometry
Metacholine rest
CXR
First line to confirm dg
Pulmonary function testing(spirometry)
Shows signs of obstructive lung disease with increased airway resistance which are
↓ FEV1,
↓ Tiffeneau index (FEV1/FVC ratio)
Obstruction is reversible w/ bronchodilators which dx from COPD and confirms dg
Metacholine test 2nd line (spirometry insufficient)
Determines airway hyper responsiveness
Metacholine is a bronchoconstricter
Spirometry is done before and after increasing doses of metacholine is inhaled
↓ FEV1 at lower doses shows HYPERREACTIVITY
Chest x-ray in severe asthma to exclude dx
(pneumonia, pneumothorax)
mild cases: moral
Severe: signs of pulmonary hyperinflation (more air)
-Low, flattened diaphragm
-Wide intercostal spaces
-Barrel chest
Explain the lung function parameters
Tidal volume: normal amount you breath in and out
Inspiratory reserve volume: vol of air forcefully/ deeply inspired
Expiratory reserve volume: volume of air forcefully expired
Reserve vol: air that remains in lungs after expiration
Total lung capacity: all of the lung stuff that’s not FEVC stuff (IRV+ERV+TV+RV) 6L In adult Male
Forced residual capacity: ERV + RV
Forced exploratory viral capacity: vol of air forcefully expired after a deep/ forceful inspiration (IRV+ERV) usually measured up to 10 seconds
5L In adult Male
FEV1: is forced expiratory vital capacity in one second 4L in healthy adult Male
FEV1/FEVC ratio is the forced expiratory vital capacity in one second divided by forced expiratory vital capacity.
0.7/ 70% in healthy adult Male
Lung function values in diff diseases
OBSTRUCTIVE
IRV: decreases
Take in less air d/2 instruction
FRC increases:
Damaged alveoli looses elasticity so RV increases and ERV increases to compensate for increased RV
FEV1: decreases
Obstruction and increased RV means it takes longer for air to be forcefully expired
FEV1/FEVC: decreases
FEV1 decreases but FEVC is the same or slightly less cause the expired air eventually reaches around 4L It in a longer time
RESTRICTIVE
Stiff lung means all parameters decreases except
FEV1/FEVC: normal or increased because::
FEVC: has decreased to around 4L
FEV in one second is around 3L so the ratio itself is table even though the volume is less
Paediatric dx of wheezes( basically Dx of asthma)
Before 2 years old -Viral infections/Bacterial infections -immune deficiency -CF – Аsthma (not the no1 cause) – GERD – Cardiac asthma: pulmonary congestion from LHF – BPD? – Compression on bronchus – Hemosiderrhosis
2 years and above – Аsthma: no1 cause – Infections in OLA – TB – Chronic pneumonia – Aspiration of foreign body – LHF – Compression on bronchus – GERD – Hemosiderrhosis
Paediatric signs that that reduce asthma as the dg
Maybe
Prognosis of paediatric asthma
30% of children up to 3 only suffer sx during a viral URTI
Many “grow out” asthma at school age
Kids w/ atopic fam history and intially sx during viral URTI go on to develop chronic asthma LATER
Asthma is frequent and severe in obese children
