bronchial asthma Flashcards
explain Definition , Epidemiology ,Etiology of asthma
-Definition: Bronchial asthma is defined as chronic inflammatory disease of airways characterized by increased responsiveness of the tracheobronchial tree to a multiplicity of stimuli. It is associated with widespread airway obstruction that is reversible (but not completely in some patients), either spontaneously or with treatment
-Epidemiology:
Asthma is a common disease The prevalence of asthma is rising in different parts of the world.
It can occur at any age; but it usually starts early in life. About 50% of patients develop asthma before the age of 10 and another 35% before the age of 40.
Males are affected twice as common as females in early life; this sex difference equalizes by age 30. Most cases of asthma are associated with personal or family history of allergic disease such as eczema, rhinitis and urticaria.
-Etiology Asthma is a heterogeneous disease and genetic ( atopic ) and environmental factors such as viruses , occupational exposure and allegens contribute to its initiation and continuance
. Atopy is the single most important risk factor for asthma
Asthma can be classified in to 3 types Allergic (atopic) , Nonallergic ( idiosyncratic ) and Mixed
explain Comparison of the two major types of Asthma
—-Allergic (Atopic) asthma :
1-Age of onset : Early in life
2-Family or personal history of allergy : Present
3-Skin test with intradermal injection of allergens : Positive wheal and -flare skin test
4-Serum IgE level : Elevated
5-Response to inhalation provocative test : positive
——— Non Allergic (idiosyncratic) :
1-Age of onset : late in life
2-Family or personal history of allergy : absent
3-Skin test with intradermal injection of allergens : Negative skin test
4-Serum IgE level : Normal
5-Response to inhalation provocative test : Negative
-NB! : Many patients have disease that doesn’t fit into either of the 2 categories, but instead fall into a mixed group with some features from each group. In general asthma which has its onset early in life tends to have strong allergic component, where as asthma that develops late in life tends to be nonallergic or to have mixed etiology.
explain Factors important for the genesis of asthma
1-Genetic factors
1.1Asthma has strong genetic predisposition or familial tendency
2-Stimuli that incite Asthma
2.1 Allergens : Seasonal allergens such as pollen green Non seasonal animal feathers , dust mites , molds
2.2 Pharmacologic stimuli: Aspirin , Tatrazin (coloring agent), Beta blockers such as Propranolol etc
2.3 Environmental and air pollution: in industrial and heavily populated areas. The common pollutants are ozone, nitrogen dioxide and sulfur dioxide.
2.4 Infections: Respiratory infections are the most common of the stimuli that evoke acute exacerbation of asthma. Respiratory viruses are the major factors
2.5 Exercise: is a very common precipitant of acute episodes of asthma
2.6 Emotional stress: psychological factors can worsen or ameliorate asthma
explain Pathophysiology of asthma
Pathophysiology: Asthma results from a state of persistent subacute inflammation of the airways. The airways
obstruction in asthma is due to a combination of factors. The cells thought to play important part in the inflammatory response are mast cells, eosinophils, lymphocytes and airway epithelial
cells.
These cells release inflammatory mediators which may result
Bronchoconstriction (spasm of airways smooth muscles )
Vascular congestion and edema of airways mucosa
Increased mucus production
Injury and desquamation of the airways epithelium and impaired muco-ciliary transport
explain Symptom and Signs
1-The symptoms of each asthmatic patient differ greatly in frequency and degree.
2-Some asthmatics are symptom free, with an occasional episode that is mild and brief; others have mild coughing and wheezing much of the time, punctuated by severe
exacerbations of symptoms following exposure to known allergens, viral infection, exercise etc. Psychological factors particularly those associated with crying, screaming or hard laughing may precipitate symptoms.
3-An attack usually begins acutely with paroxysms of wheezing, coughing, and shortness of breath, or insidiously with slowly increasing manifestations of respiratory distress.
4-The asthmatic first notices dyspnea, tachypnea, cough and tightness in the chest and may even notice audible wheezes.
explain physical examination
1-Varying degrees of respiratory distress tachypnea, tachycardia, and audible wheezes are often present.
2-Dehydration may be present because of sweating and tachypnea.
3-Chest examination shows a prolonged expiratory phase with relatively high pitched wheezes throughout inspiration and most of expiration.
4-In more severe episodes, patients may be unable to speak more than a few words without stopping for breath.
5-Cyanosis is usually a late sign of hypoxia.
6-Confusion and lethargy may indicate the onset of progressive respiratory failure.
7-Less wheezing (silent chest) might indicate mucous plug or patient fatigue with less airflow. And it is a sign of impending respiratory failure.
8-The presence, absence, or prominence of wheezes does not correlate precisely with the severity of the attack.
9-The most reliable clinical signs include the degree of dyspnea at rest, cyanosis, difficulty in speaking and use of accessory muscles of respiration. This is confirmed by arterial blood gas analysis.
10-Between acute attacks, breath sounds may be normal during quiet respiration. However, low grade wheezing maybe heard at any time in some patients, even when they claim to be completely asymptomatic.
explain Complications during an Acute Attack of Asthma
1-Pneumothorax: It may present as sudden worsening of respiratory distress, accompanied by sharp chest pain and on examination, hyperresonant lung with a shift of
mediastinum. Chest x-ray confirms the diagnosis.
2-Mediastinal and subcutaneous emphysema due to alveolar rupture
3-Atelectasis due to obstruction
4-Dilated right heart chambers (Corpulmonale) : from chronic hypoxemia and pulmonary hypertension
5-Respiratory failure
explain Laboratory Findings , Diagnosis , Differential diagnosis
–Laboratory Findings
1-Eosinophilia is a common finding.
2-Sputum is tenacious, rubbery and whitish or may be yellowish; eosinophils are present in the sputum.
3-Chest x-ray: varies from normal to hyperinflation. Atelectasis and pneumothorax may be seen in complicated cases.
4-Pulmonary function tests are valuable in differential diagnosis and in known patients to assess the degree of airways obstruction
–Diagnosis : Asthma should be considered in anyone who wheezes. A family history of allergy, rhinitis or asthma can be elicited in most asthmatics.
–Differential diagnosis includes:
1-In children: foreign body obstruction, viral URTI involving the epiglottis (croup), and bronchiolitis (RSV infection);
2-In adults: COPD, heart failure, endobronchial TB, and malignancies. Physical examination should search for heart failure and signs of chronic hypoxemia (clubbing). Unilateral wheezes usually indicate obstruction by foreign bodies or tumor.
explain the Prevention of attacks
1-The role of environmental factors (e.g. animal dander, dust, airborne moulds, and pollens) in acute exacerbations is clear. Allergens that can be controlled by avoidance should be eliminated.
2-Nonspecific exacerbating factors (e.g. cigarette smoke, odors, irritant fumes, and change in temperature, atmospheric pressure, and humidity) should also be investigated and avoided if possible.
explain Treatment , General principles , Treatment of the Acute Attack ,
-General principles
1-Assessing the severity of the attack is paramount in deciding management
2-Bronchodilators should be used in orderly progression
3-Decide when to start corticosteroids
-Treatment of the Acute Attack: Mild acute asthmatic attack: Most patients can be managed as an outpatient :
1-Salbutamol aerosol (Ventolin®) two puffs every 20 minutes for three doses is the 1st line of treatment.
2-Adrenaline 1:1000 can be given in doses up to a maximum of 0.2 ml in children and 0.3 ml in adults, repeated once or twice in 20 to 30 min (if there is no hypertension or any other contra indication).
3-If the initial treatment fails, Aminophylline 250 mg IV diluted in dextrose in water should be given slowly over 10-15 minutes, once.
4-If the patient does not respond to one dose of aminophylline IV, then the patient is declared to have severe asthma, and should be admitted and managed as in-patient
explain Signs of Severity of acute asthmatic attack , Specific drug Treatment ,Supportive Treatment
-Signs of Severity of acute asthmatic attack
1) Tachycardia HR > 120/min , Tachypnea RR.30 min
2) Presence of pulsus paradoxus
3) Use of accessory muscles of respiration
4) Cyanosis
5) Altered state of consciousness ( confusion , drowsiness )
6) Silent chest
7) Paradoxical movement of the chest and the abdomen
8) Presence of complications : Pneumothorax , atelectasis
9) Unable to finish a sentence with single breath ( frequent interruption of speech to take a breath )
10) Laboratory parameters
o PEFR < 50 % or FEV1 < 60 %
o PaO2 < 60mmof Hg or SaO2 < 90 %
o PaCO2 > 42 mmHg
-Specific drug Treatment
1-Aminoplylline in doses of 1mg/kg/hr in a continuous IV infusion should be given.
2-Corticosteroids should also be given IV e.g. Hydrocortisone 4mg/kg IV every 4 hrs. When the patient improves the hydrocortisone be changed to Prednisolone PO and the
dosage should be tapered up on discharge.
3-Patients who do not respond to aggressive drug therapy are candidates for endotracheal intubation and Mechanical Ventilation for which they should be admitted to an ICU.
4-Respiratory tract infections precipitating acute asthmatic attack are predominantly viral; but if patients expectorate yellowish, green or brown sputum, antibacterial therapy is
indicated. Ampicillin is the first line; alternatives are TTC, erythromycin or cotrimoxazole. Chest x-ray is taken if there is suspicion of pneumonia or complications.
–Supportive Treatment
1-O2 therapy is always indicated for hospitalized patients
2-Fluid and electrolyte balance requires special attention because of frequent occurrence of dehydration during acute asthmatic attack. However, over hydration may cause pulmonary edema and one should be cautious in fluid administration.
3-Anxiety is common in patients with severe acute asthmatic attack. However this can be overcome when underlying hypoxia and feeling of asphyxiation is treated. Health personnel should be considerate and reassure the patient
explain Maintenance Therapy for Asthma (Chronic Treatment)
-Maintenance Therapy for Asthma (Chronic Treatment) :Goal of Therapy: To achieve a stable, asymptomatic state with the best pulmonary function, using the list amount of medication .Drug selection is based upon the severity of illness.
–Step wise approach for managing Asthma in adults :
1-Severity :Mild intermittent
-Symptoms day/night : ≤ 2 days/wk and ≤ 2 nights /month
-Medication : No daily medication needed Treat when there is acute exacerbation
-Alternative treatment in resource limited setting : —–
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2-Severity :Mild Persistent
-Symptoms day/night :> 2days /week but <
1 per day and > 2 nights/month
-Medication :Low dose inhaled steroids
or Cromolyn
-Alternative treatment in resource limited setting : Theophedrine tablets or Salbutamol tabs
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3-Severity :Moderate Persistent
-Symptoms day/night : Daily symptoms and more than 1 night /wk
-Medication :Low-medium does inhaled steroid and long acting
B-agonist inhaler
-Alternative treatment in resource limited setting :
Theophylline sustained release
Salbutamol Tabs
Prednisolone tablets (low dose)
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4-Severity :Sever Persistent
-Symptoms day/night : Continual daily symptoms and frequent night symptoms
-Medication : High dose inhaled steroid and long acting inhaled B-agonists and Oral steroids ( if needed )
-Alternative treatment in resource limited setting :
Theophylline
sustained release
Salbutamol Tabs
Prednisolone tablets (high dose) or
Celestamine tabs
