Asthma Flashcards
Asthma
A chronic inflammatory disorder of the airways characterized by:
- recurring symptoms
- airway obstruction (reversible spontaneously or with treatment)
- bronchial hyper-responsiveness to stimuli
Most common chronic childhood illness
Major cause of school absenteeism, visits to emergency, and hospital admissions
Incidence
1-2 kids in 10 children
More common in boys (until adolescence), then trend reverses
80-90% have symptoms before 4-5 years
2 main types
- recurrent wheezing in early childhood; usually precipitated by viral infections (RSV)
- chronic asthma associated with allergy persisting into later childhood & often adulthood
Classification of Asthma, ages 5-11 years: Step 1
Intermittent Asthma:
- symptoms < 2 days/week
Classification of Asthma, ages 5-11 years: Step 2
Mild Persistent Asthma
- symptoms > 2 times/week, but < once/day
Classification of Asthma, ages 5-11 years: Step 3 or 4
Moderate Persistent Asthma
- daily symptoms
Classification of Asthma, ages 5-11 years: Step 5 or 6
Severe persistent Asthma
- symptoms several times a day
Purpose of Step Classification for Asthma
provides stepwise approach to pharmacologic management, environmental control & educational interventions needed at each step
Etiology
Multifactorial - biochemical, genetic, immunologic, environmental, infectious, endocrine, & psychological factors
Allergy influences persistence& severity of disease -> atopy (IgE - mediated respones to common aeroallergens) is strongest identifiable predisposing factor for developing asthma
BUT: 20-40% have no evidence of any allergic disease and still acquire asthma
Risk Factors (8)
atopy (including hx of allergies or atopic dermatitis)
heredity (e.g., parent/sibling)
Gender (boys > girls until adolescence then girls > boys)
Smoking or exposure to second-hand smoke
Maternal smoking during pregnancy
Ethnicity (african-american at greatest risk)
Low birthweight
Being overweight
Examples of Triggers
Allergens - trees, shrubs, grasses, pollens, air pollution, dust mites, dust, pollens, mould, smoke, sprays
Occupational chemicals
Physical exercise
Cold air
Weather or temperature changes
Environmental change
Cold & infections - viral or bacterial
Animals - cats, dogs, rodents, horses
Medications - aspirin, NSAIDS, antibiotics
Strong emotion - fear, anger, laughing, crying
Foods - nuts, milk, diary
Conditions - GER, TEF
Endocrine factors - menses, pregnancy, thyroid disease
Pathophysiology
Initial release of inflammatory mediators from bronchial mast cells, macrophages, & epithelial cells
Migration & activation of other inflammatory cells
Alterations in epithelial integrity & autonomic neural control of airway tone
Increase in airway smooth muscle responsiveness -> wheezing, dyspnea, & eventual obstruction
Mast cells release histamine which leaks into the airway and then the more severe reaction starts -> brochospasm, airway is getting close and mucus is being produced
Pathophysiology - Obstructive Symptoms
Inflammation & edema of mucous membranes
Accumulation of tenacious secretions from mucous glands
Spasm of smooth muscle of bronchi & bronchioles -> decreases caliber of bronchioles
Could be mucus plugging the alveoli
Two mainstays of treatment: first one deals with diameter of the airway - something to relax the bronchospasm (beta 2 agonist - salbutamol or ventolin)
second one: anticholinergic to clear the mucus (atrovent or ipratropium)
What causes an asthmatic episode?
some asthma triggers are exercise, infection, and allergies. Asthma obstructions airflow through bronchoconstriction and inflammatory changes, narrowing the airway and thus increasing production of mucus. Alveoli may become hyperinflated or collapse because of obstruction, leading to impaired gas exchange.
Pathophysiology: immunologic factors
Allergy is strongest epidemiologic risk factor for chronic asthma morbidity & mortality -> IgE is most active antibody in allergic reactions. Mediates hypersensitive reaction in bronchial mucosa -> specific tissue binding
Immunologic Factors: Release of chemical mediators
Histamine, leukotrienes, platelet-activating factor, prostaglandins, serotonin
Major effect:
- increased permeability of blood vessels
- contraction of smooth muscle
- stimulation of mucous secretion
Pathophysiology: Vagal Stimulation
Balance of vagal & sympathetic nerve influences maintenance of tone of bronchial smooth muscle -> irritant receptors react to triggers & stimulate reflex bronchospasm -> normal response but in asthma this is abnormally severe
Pathophysiology: Ventilation
Increased airway resistance -> forced expiration -> air trapping -> increased WOB: fatigue, decreased respiratory effectiveness, increased O2 consumption, decreased effectiveness of cough, dyspnea, cyanosis, tachypnea
Pathophysiology: Gas exchange
Depends on ratio of poorly ventilated & hyperextended alveoli to well-ventilated alveoli
-> as severity of obstruction increases -> reduced alveolar ventilation: CO2 retention, hypoxemia, respiratory acidosis, respiratory failure
Pathophysiology - Exacerbations
Episodes of progressively worsening SOB, cough, wheezing, chest tightness
Decreases in expiratory airflow: airways narrow because of bronchospasm, mucosal edema, & mucous plugging -> air trapped behind narrowed airways
Hyperventilation -> keeps airways open & permits gas exchange
Hypoxemia -> ventilation/perfusion mismatch
Clinical Manifestations: Classic
Dyspnea
Wheezing
Coughing
Clinical Manifestations other
prodromal itching (frontal neck or upper part of back)
breathing changes -> wheezing
mood changes -> feeling uncomfortable or irritable & increasingly restless
headache, feeling tired or chest feels “tight”
Hacking, paroxysmal, irritative & non-productive cough which becomes productive as secretions accumulate
coughing in absence of resp infection esp at night (interferes with sleep)
Getting worse (8)
SOB, prolonged expiratory phase, audible wheezing, increased RR & HR, shallow breathing
Pale -> cyanosis
Restless & apprehensive -> anxious facial expression; irritability
listlessness
Sweating
position
Voice changes - short, panting, broken phrases
Retractions
Pediatric Respiratory Assessment Measure (PRAM)
puts the assessment into the objective data category
done on patient with asthma symptoms and done before they get treatment and after they get treatment
want low scores
PRAM Criterions (WOSSA)
O2 sat
Suprasternal retractions
Scalene muscle contraction
Air entry
Wheezing
Inpatient Asthma Management pathway
want to know if it is working. do PRAM score after administration
Asthma diagnosed after 3 wheezing episodes
Complications
Increased susceptibility to infections
Atelectasis
Emphysema
Pneumothorax
Status asthmaticus
Diagnostic Evaluation
Clinical manifestations, history, physical examination, & lab tests
Pulmonary function tests
Peak expiratory flow rate
- green, yellow, or red zone based on personal best value (do it three times and record highest number)
Skin testing -> allergies
CBC, CXR
Detailed History
Current symptoms - medications, triggers
History of attacks - seasonal, with colds (hospitalizations, intubated)
Family History - asthma or allergies
Paint the picture (compare attacks, look at differences)
Chest Assessment
Observation: colour, tachypnea, rhythm, cough, wheezing, difficulty, accessory muscles, indrawing, irritable, tachycardia, posture, fever, cold s/s
Auscultation: air entry, breath sounds, crackles, wheezes, movement of air. changes with coughing, medications
Tests: CXR, PEFR, ABGs, O2 sats
Therapeutic Management
Allergen control: house dust mites, cockroach
Drug therapy
Breathing exercises & physical training
Hypo-sensitization
Exercise
Supportive Care
Maintain patent airway - humidified O2; positioning (raise HOB)
Rest & stress reduction - group care; quiet environment
Fluids - warm, may need IV
Medications
Avoidance of triggers
Reassurance - child and family
Discharge planning & teaching
Medications: Corticosteroids - anti-inflammatories
inhaled - preventors: fluticasone (flovent), budesnide (pulmicort), beclomethasone (beclovent)
Oral: prednisone, prednisolone, dexamethasone
IV: Methylprednisolone
Discharged home on and take regularly. 1 puff twice a day
Medications: Beta2 agonists - “rescuers” or “relievers”
Salbutamol (ventolin), salmeterol (serevent), terbutaline (bricanyl)
have this during asthma attacks or exacerbations
Medications: Anticholinergics
Ipratropium (atrovent)
Medications: magnesium sulphate
Rescuer - bronchodilator: used for severe or life-threatening exacerbations
- given IV. monitor for hypotension, arrhythmias, do cardiorespiratory monitoring and BP monitoring every 5 min
Methylxanthines
Rescuers
Aminophylline
used primarily in emergency department when unresponsive to other therapy
Mast Cell Inhibitors
Preventors
Cromolyn sodium, nedocromil sodium
Leukotriene receptor antagonists
Preventors
Zafirlukast, Montelukast sodium
