| History: A complete medical history is obtained, including the presence of typical symptoms (wheezing, shortness of breath, cough, chest tightness, sputum production, decreased exercise tolerance); any patterns associated with symptoms (time of day, season); duration, severity, and frequency of symptoms; age at onset and course of disease (emergency department visits, hospitalizations, ICU admissions, intubations); known precipitating or aggravating factors; other medical conditions; current medications; family history (asthma, allergy, rhinitis, eczema); social history (exposure to smoke); occupational history; and recreational history.
Asthma attacks are typically episodic. Intervals between attacks can be days, months, or years; for some people asthma can be a daily problem. The symptoms of asthma vary and are related to the severity of airway obstruction. Common symptoms during attacks include wheezing, coughing, chest tightness, and shortness of breath. Individuals may only be able to speak in one- to two-word sentences. If severe airway obstruction interferes with the delivery of oxygen to the brain, individuals can become restless and confused. Exercise may precipitate asthma. Between attacks, symptoms are absent or greatly reduced. Any information about events preceding an attack can be useful to determine a possible trigger for the asthma, but in some cases of hyper-reactive airways, it can be difficult to isolate the cause(s).
Symptoms of occupational asthma are the same as nonoccupational asthma and may include wheezing, shortness of breath, chest tightness, and cough. Other associated symptoms may include runny nose, nasal congestion, and eye irritation. The cause may be allergic or nonallergic in nature, and the disease may persist for a lengthy period in some workers, even after they have discontinued exposure to the irritants that triggered their symptoms. Commonly, symptoms worsen through the workweek, improve over the weekend or while on vacation, and recur when the worker returns to the job. Physical exam: Physical examination begins with observation of the patient. Signs of respiratory distress may include increased rapid breathing (tachypnea), a rapid heart rate (tachycardia), using the accessory muscles in the neck to help breathe, sweating (diaphoresis), and a bluish tinge to the skin (cyanosis). Use of a stethoscope to listen to the chest (auscultation) may reveal wheezing that is more prominent on exhalation and decreased breath sounds. The examination of an individual with asthma may be completely normal between attacks.
The nose may be examined for the presence of nasal polyps, any other type of nasal obstruction, and signs of allergic rhinitis. The skin may be examined for signs of atopic dermatitis, eczema, or other allergic skin conditions. Tests: Pulmonary function testing (spirometry) is important in establishing the diagnosis of asthma and should be performed before treatment and after administration of a short-acting bronchodilator. During an acute asthmatic attack, spirometry will show diminished lung capacity and flow rate (peak flow) on exhalation. The diagnosis of asthma cannot be made solely on the basis of spirometry, since many other diseases cause similar findings. Also, pulmonary function may appear normal between asthma attacks. Arterial blood gases and an ECG may be indicated if the asthma attack is severe and/or prolonged.
Peak flow testing is a simple and highly effective tool that can be used at home to monitor response to medications and detect exacerbations early, although it is not a substitute for spirometry. Peak flow should be monitored on arising before use of a bronchodilator.
Methacholine challenge tests can be used in special circumstances to diagnose hyper-reactive airways when pulmonary function tests are normal and asthma is suspected. If asthma is present only on the job, it may be necessary to measure airflow in the workplace with a portable peak flow meter or to have spirometry done before and after work. Qualitative and quantitative tests for possible air and gas triggers may also be performed.
Exercise spirometry with cycle ergometry, treadmill, or free running may be done to evaluate possible EIA. If symptoms and physical signs respond positively to the administration of bronchodilators, partially reversing the airflow measurements, this will confirm a diagnosis of asthma. Pulse oximetry will quickly measure the oxygen level in the blood.
A complete blood count (CBC) with WBC differential may show an increased eosinophil count (greater than 4%) in allergic asthma. A microscopic examination of sputum may be done to determine sputum eosinophil count to monitor therapy or if an infection is suspected. Most allergic asthmatics have an elevated specialized protein (total serum immunoglobulin E, or IgE) level in their blood. Skin testing for allergens may be done in some individuals, or blood radioallergosorbent tests (RAST) may be performed to determine factors involved in precipitating attacks. |