Asthma is a predispositionto chronic inflammation of the lungs in which the airways(bronchi)are reversibly narrowed. During asthmaattacks (exacerbations of asthma), the smooth muscle cells in thebronchi constrict, the airways become inflamed and swollen, and breathingbecomes difficult. This is often referred to as a tight chest and is a sign toimmediately take medication.
Asthma is a chronic obstructive pulmonary disease;however, in contrast to the other disorders in the COPD definition—bronchiectasis,chronic bronchitis, and emphysema—theairway obstruction in asthma is reversible. In contrast to emphysemaand bronchiectasis,asthma affects the bronchi, not the alveoli.
Asthma exists in two states: the steady-state of chronic asthma, and theacute state of an acute asthma exacerbation. The symptoms are differentdepending on what state the patient is in.
Common symptoms of asthma in a steady-state include: night time coughing,shortness of breath with exertion but no dyspneaat rest, a chronic 'throat-clearing' type cough, and complaints of a tightfeeling in the chest. Severity often correlates to an increase in symptoms.Symptoms can worsen gradually and rather insidiously, up to the point of anacute exacerbation of asthma. It is a common misconception that all people withasthma wheeze—some never wheeze, and their disease may be confused with anotherchronic obstructive pulmonary diseasesuch as emphysemaor chronic bronchitis.
An acute exacerbation of asthma is commonly referred to as an asthma attack. The cardinal symptomsof an attack are shortness of breath (dyspnea),wheezing,and chest tightness.Although the former is often regarded as the primary symptom of asthma, somepatients present primarily with coughing, and in the late stages of an attack, air motion maybe so impaired that no wheezing may be heard. When present the cough maysometimes produce clear sputum. The onset may be sudden, with a sense of constrictionin the chest, as breathing becomes difficult and wheezing occurs (primarilyupon expiration, but sometimes in both respiratory phases). It is important tonote inspiratory stridorwithout expiratory wheezehowever, as an upper airway obstruction may manifest with symptoms similar toan acute exacerbation of asthma, with stridor instead of wheezing, and willremain unresponsive to bronchodilators.
Signsof an asthmatic episode include wheezing, prolonged expiration, a rapid heartrate (tachycardia),and rhonchouslung sounds (audible through a stethoscope).During a serious asthma attack, the accessory muscles ofrespiration (sternocleidomastoid and scalene muscles of the neck) may be used,shown as in-drawing of tissues between the ribs and above the sternumand clavicles,and there may be the presence of a paradoxicalpulse (a pulse that is weaker during inhalation and stronger duringexhalation), and over-inflation of the chest.
During very severe attacks, an asthma sufferer can turn bluefrom lack of oxygen and can experience chest painor even loss of consciousness. Just before loss ofconsciousness, there is a chance that the patient will feel numbness in thelimbs and palms may start to sweat. The person's feet may become cold. Severeasthma attacks which are not responsive to standard treatments, called status asthmaticus, are life-threatening andmay lead to respiratory arrest and death.
Though symptoms may be very severe during an acute exacerbation, betweenattacks a patient may show few or even no signs of the disease.