asthma Flashcards
what is asthma?
Asthma is a chronic inflammatory disease of the airways characterized by reversible episodes of increased airway hyperresponsiveness resulting in recurrent episodes of dyspnea, coughing, and wheezing.17 The bronchiolar lung tissue of patients with asthma is particularly sensi- tive to a variety of stimuli. Overt attacks may be pro- voked by allergens, upper respiratory tract infection, exercise, cold air, certain medications (salicylates, nonsteroidal antiinflammatory drugs, cholinergic drugs, and β-adrenergic blocking drugs), chemicals, smoke, and highly emotional states such as anxiety, stress, and nervousness.
what are the four categories of asthma triggers?
Many triggers of asthma are recognized; these factors traditionally have been grouped into one of four catego- ries based on pathophysiology: extrinsic (allergic or atopic), intrinsic (idiosyncratic, nonallergic, or non- atopic), drug-induced, and exercise-induced. Today, from a management perspective, the type of trigger is more important than the category.
what’s the most common form of asthma?
Allergic or extrinsic asthma is the most common form and accounts for approximately 35% of all adult cases. It is an exaggerated in ammatory response that is trig- gered by inhaled seasonal allergens such as pollens, dust, house mites, and animal danders. Allergic asthma usually is seen in children and young adults.22 In these patients, a dose-response relationship exists between allergen exposure and immunoglobulin E (IgE)–mediated sensiti- zation, positive skin testing to various allergens, and associated family history of allergic disease.
what happens during an extrinsic asthma attack?
allergens interact with IgE antibodies af xed to mast cells, basophils, and eosinophils along the tracheobron- chial tree. The complex of antigen with antibody causes leukocytes to degranulate and secrete vasoactive auto- coids and cytokines such as bradykinins, histamine, leukotrienes, and prostaglandins.23 Histamine and leu- kotrienes cause smooth muscle contraction (broncho- constriction) and increased vascular permeability, and they attract eosinophils into the airway.24 The release of platelet-activating factor sustains bronchial hyperre- sponsiveness. Release of E-selectin and endothelial cell adhesion molecules, neutrophil chemotactic factor, and eosinophilic chemotactic factor of anaphylaxis is res- ponsible for recruitment of leukocytes (neutrophils and eosinophils) to the airway wall, which increases tissue edema and mucus secretion. T lymphocytes prolong the in ammatory response (late-phase response), and imbal- ances in matrix metalloproteinases and tissue inhibitor metalloproteinases may contribute to brotic changes.
what is intrinsic asthma?
Intrinsic asthma accounts for about 30% of asthma cases and seldom is associated with a family history of allergy or with a known cause. Patients usually are non- responsive to skin testing and demonstrate normal IgE levels. This form of asthma generally is seen in middle- aged adults, and its onset is associated with endogenous factors such as emotional stress (implicated in at least 50% of affected persons), gastroesophageal acid re ux, or vagally mediated responses.24
drugs and food and asthma?
Ingestion of drugs (e.g., aspirin, nonsteroidal antiin- flammatory drugs, beta blockers, angiotensin-converting [ACE] enzyme inhibitors) and some food substances (e.g., nuts, shell fish, strawberries, milk, tartrazine food dye yellow color no. 5) can trigger asthma.25 Aspirin causes bronchoconstriction in about 10% of patients with asthma, and sensitivity to aspirin occurs in 30% to 40% of people with asthma who have pansinusitis and nasal polyps (the so-called “triad asthmaticus”).25 The ability of aspirin to block the cyclooxygenase pathway appears causative. The buildup of arachidonic acid and leukotrienes mediated by the lipoxygenase pathway results in bronchial spasm.25,26
what about exercise induced asthma/
Exercise-induced asthma is stimulated by exertional activity. Although the pathogenesis of this form of asthma is unknown, thermal changes during inhalation of cold air provoke mucosal irritation and airway hyper- activity. Children and young adults are more severely affected because of their high level of physical activity.
what about infectious asthma?
Infectious asthma is a term previously used to describe persons who developed asthma because of the inflam- matory response to bronchial infection. Now it is recognized that several respiratory viral infections during infancy and childhood can result in the development of asthma. Also, causative agents of respiratory infections (bacteria, dermatologic fungi I Trichophyton), and Myco- plasma organisms) can exacerbate asthma. Treatment of the respiratory infection generally improves control of bronchospasm and constriction.
what about the pathophysiology?
In asthma, obstruction of air flow occurs as the result of bronchial smooth muscle spasm, inflammation of bron- chial mucosa, mucus hypersecretion, and sputum plug- ging. The most striking macroscopic finding in the asthmatic lung is occlusion of the bronchi and bronchi- oles by thick, tenacious mucous plugs (Figure 7-7). His- tologic findings are those of inflammation and airway remodeling, including (1) thickening of the basement membrane (from collagen deposition) of the bronchial epithelium, (2) edema, (3) mucous gland hypertrophy and goblet cell hyperplasia, (4) hypertrophy of the bron- chial wall muscle, (5) accumulation of mast cell and inflammatory cell infiltrate, (6) epithelial cell damage and detachment, and (7) blood vessel proliferation and dilation.28 These changes contribute to decreased diam- eter of the airway, increased airway resistance, and dif- culty in expiration.
complications of asthma? what’s the most serious ?
Asthma is relatively benign in terms of morbidity. Most patients can expect a reasonably good prognosis, especially those in whom the disease develops during childhood. In many young children, the condition resolves spontaneously after puberty. In one reported series, however, two thirds of asthmatic children still had symptoms at age 21 years.29 In a small percentage of patients, both young and old, the condition can progress to COPD and respiratory failure, or status asthmaticus,
the most serious manifestation of asthma, may occur. Status asthmaticus is a particularly severe and prolonged asthmatic attack (one lasting longer than 24 hours) that is refractory to usual therapy. Signs include increased and progressive dyspnea, jugular venous pulsation, cya- nosis, and pulsus paradoxus (a fall in systolic pressure with inspiration). Status asthmaticus often is associated with a respiratory infection and can lead to exhaustion, severe dehydration, peripheral vascular collapse, and death. Although death directly attributable to asthma is relatively uncommon, the disease causes more than 4000 deaths per year in the United States. Asthma deaths occur more often in persons older than 45 years of age, are largely preventable, and often are related to delays in delivery of appropriate medical care.29
What is salbutamol and how does it help asthmatics? By what routes should it be administered? what happens if used excessively?
Salbutamol (marketed as Ventolin) is a short acting B2 agonist which is to be used during an acute asthma attack. B2 agonists are the choice for fast relief of acute asthma attacks due to their fast bronchodilatory and smooth muscle relaxation properties. Salbutamol is often administered through use of a metered-dose inhaler, but can also be administered through a nebulizer, a pill, or through an IV route.
The use of B2 agonists can cause tremors and tachycardia, and prolonged use can lead to tolerance of the drug.
what is well controlled for asthma?
As already mentioned, a well controlled asthmatic should not need to use salbutamol more than 4 times in a week.
what can happen in some children that may be getting local anesthetic for the first time?
. Epinephrine containing LA is metabolized by sulfite oxidase. Low metabolic levels of sulfite oxidase will result in an increase in sulfur dioxide build-up in the bronchial tree – the result is an acute asthma attack.
