Introduction• Asthma is a syndrome characterized by airflow obstruction that varies markedly, both spontaneously and with treatment. Asthmatics harbor a special type of inflammation in the airways that makes them more responsive than nonasthmatics to a wide range of triggers, leading to excessive narrowing with consequent reduced airflow and symptomatic wheezing and dyspnea. Narrowing of the airways is usually reversible, but in some patients with chronic asthma there may be an element of irreversible airflow obstruction. The increasing global prevalence of asthma, the large burden it now imposes on patients, and the high health care costs have led to extensive research into its mechanisms and treatment.
Prevalence• Asthma is one of the most common chronic diseases globally and currently affects approximately 300 million people worldwide. The prevalence of asthma has risen in affluent countries over the last 30 years but now appears to have stabilized, with approximately 10–12% of adults and 15% of children affected by the disease. In developing countries where the prevalence of asthma had been much lower, there is a rising prevalence, which is associated with increased urbanization. The prevalence of atopy and other allergic diseases has also increased over the same time, suggesting that the reasons for the increase are likely to be systemic rather than confined to the lungs. This epidemiologic observation suggests that there is a maximum number of individuals in the community, who are likely to be affected by asthma, most likely by genetic predisposition. Most patients with asthma in affluent countries are atopic, with allergic sensitization to the house dust mite Dermatophagoides pteronyssinus and other environmental allergens.• Because asthma is both common and frequently complicated by the effects of smoking on the lungs, it is difficult to be certain about the natural history of the disease in adults. Asthma can present at any age, with a peak age of 3 years. In childhood, twice as many males as females are asthmatic, but by adulthood the sex ratio has equalized. The commonly held belief that children "grow out of their asthma" is justified to some extent. Long-term studies that have followed children until they reach the age of 40 years suggest that many with asthma become asymptomatic during adolescence but that asthma returns in some during adult life, particularly in those with persistent symptoms and severe asthma. Adults with asthma, including those with onset during adulthood, rarely become permanently asymptomatic. The severity of asthma does not vary significantly within a given patient; those with mild asthma rarely progress to more severe disease, whereas those with severe asthma usually have severe disease at the onset.
Histopathology of a small airway in fatalasthma
KEY INDICATORS FOR CONSIDERING A DIAGNOSIS OF ASTHMA? Wheezing—high-pitched whistling sounds when breathing out—especially in children. (Lack of wheezing and a normalchest examination do not exclude asthma.)? History of any of the following:— Cough, worse particularly at night— Recurrent wheeze— Recurrent difficulty in breathing— Recurrent chest tightness
KEY INDICATORS FOR CONSIDERING A DIAGNOSIS OF ASTHMA? Symptoms occur or worsen in the presence of:— Exercise— Viral infection— Animals with fur or hair— House-dust mites (in mattresses, pillows, upholstered furniture, carpets)— Mold— Smoke (tobacco, wood)— Pollen— Changes in weather— Strong emotional expression (laughing or crying hard)— Airborne chemicals or dusts— Menstrual cycles? Symptoms occur or worsen at night, awakening the patient.
Assess for the following• Vital signs• Patient’s ability to speak in sentences• Accessory muscle use• Lung sounds
Normal BronchovesicularNormal sounds heard in the peripheryof all lung fields.
Normal BronchialNormal sounds heard toward thecenter of the chest over the largerairways.
Wheezes―Musical‖ sounds heard when there isa constriction of the bronchioles.In general the higher the pitchthe tighter the bronchioles.A “quiet” chest is the worstcase scenario
Other Causes of Wheezing• Aspiration• Certain drugs• Chronic obstructive pulmonary disease• Endobronchial tumors• Endotracheal tumors• Inhaled irritants• Tracheal stenosis• Viral tracheobronchitis• Vocal cord dysfunction• Pulmonary edema (CHF)
Diagnosis• Lung Function Tests• Simple spirometry confirms airflow limitation with a reduced FEV1, FEV1/FVC ratio, and PEF. Reversibility is demonstrated by a >12% and 200-mL increase in FEV1 15 minutes after an inhaled short-acting 2-agonist or in some patients by a 2 to 4 week trial of oral corticosteroids (OCS) (prednisone or prednisolone 30–40 mg daily). Measurements of PEF twice daily may confirm the diurnal variations in airflow obstruction. Flow-volume loops show reduced peak flow and reduced maximum expiratory flow. Further lung function tests are rarely necessary, but whole body plethysmography shows increased airway resistance and may show increased total lung capacity and residual volume. Gas diffusion is usually normal, but there may be a small increase in gas transfer in some patients.
• Stepwise approach to asthma therapy according to the severity of asthma and ability to control symptoms
QUICK-RELIEF MEDICATIONSInhaled SABA:Albuterol Levalbuterol PirbuterolAnticholinergics :Ipratropium bromide• Usual Adult Dose for Asthma - AcuteMetered-dose inhaler: 2 puffs every 4 to 6 hours as needed.Inhalation capsules: 200 mcg inhaled every 4 to 6 hours.May increase to 400 mcg inhaled every 4 to 6 hours, if necessary.Nebulizer: 2.5 mg every 6 to 8 hours as needed. (2.5 to 5 mg oncefollowed by 2.5 mg every 20 minutes for acute bronchospasm).
LONG-TERM CONTROL MEDICATIONS• Corticosteroids (Glucocorticoids)Inhaled (ICS):Beclomethasone dipropionateBudesonide, FlunisolideFluticasone propionateMometasone furoateTriamcinolone acetonideSystemic:Methylprednisolone , Prednisolone , PrednisoneAdults: Dosage is determined by the condition being treated and your response tothe drug. Typical starting doses can range from 5 milligrams (mg) to 60 mg a day.Once you respond to the drug, your doctor will lower the dose gradually to theminimum effective amount.
Aspirin-Sensitive AsthmaA small proportion (1–5%) of asthmatics become worse with aspirin and otherCOX inhibitors, although this is much more commonly seen in severe cases and inthose patients with frequent hospital admission. Aspirin-sensitive asthma is a welldefined subtype of asthma that is usually preceded by perennial rhinitis and nasalpolyps in nonatopic patients with a late onset of the disease. Aspirin, even in smalldoses, characteristically provokes rhinorrhea, conjunctival irritation, facialflushing, and wheezing. There is a genetic predisposition to increased productionof cysteinyl-leukotrienes with functional polymorphism of cys-leukotriene Csynthase. Asthma is triggered by COX inhibitors, but is persistent even in theirabsence. All nonselective COX inhibitors should be avoided, but selective COX2inhibitors are safe to use when an anti-inflammatory analgesic is needed. Aspirin-sensitive asthma responds to usual therapy with ICS. Although antileukotrienesshould be effective in these patients, they are no more effective than in allergicasthma. Occasionally, aspirin desensitization is necessary, but this should only beundertaken in specialized centers.
Asthma in the ElderlyAsthma may start at any age, including in elderly patients.The principles of management are the same as in otherasthmatics, but side effects of therapy may be a problem,including muscle tremor with 2-agonists and more systemicside effects with ICS. Comorbidities are more frequent in thisage group, and interactions with drugs such as 2-blockers,COX inhibitors, and agents that may affect theophyllinemetabolism need to be considered. COPD is more likely inelderly patients and may coexist with asthma. A trial of OCSmay be very useful in documenting the steroid responsivenessof asthma.
PregnancyApproximately one-third of asthmatic patients who are pregnant improveduring the course of a pregnancy, one-third deteriorate, and one-third areunchanged. It is important to maintain good control of asthma as poorcontrol may have adverse effects on fetal development. Compliance maybe a problem as there is often concern about the effects of antiasthmamedications on fetal development. The drugs that have been used formany years in asthma therapy have now been shown to be safe andwithout teratogenic potential. These drugs include short-acting 2-agonists,ICS, and theophylline; there is less safety information about newer classesof drugs such as LABAs, antileukotrienes, and anti-IgE. If an OCS isneeded, it is better to use prednisone rather than prednisolone as it cannotbe converted to the active prednisolone by the fetal liver, thus protectingthe fetus from systemic effects of the corticosteroid. There is nocontraindication to breast-feeding when patients are using these drugs.