**2. Clinical assessment: physical examination and medical history**

The signs and symptoms of asthma vary widely among every individual, as well as over time. This reversible airway obstruction pulmonary disease is characterized by the presence of several symptoms including nonproductive cough, chest tightness, episodic wheezing and dyspnea usually brought spontaneously or after exposures of

identified triggers or stimuli and relieved or improved with the use of bronchodilator therapy. Diagnosis is often difficult, as clinical presentation is nonspecific and my overlap with other comorbidities. The diagnosis of asthma involves a careful and detailed process of history taking, physical examination, laboratory studies and diagnostic studies which demonstrate variable expiratory airflow obstruction [ 14 ]. Asthma can affect any age, but is more common during childhood years, till many patients may have a remission of the disease during puberty with recurrence of the disease once day enter adulthood. Most cases of adult-onset asthma are usually related to occupational exposure, associated with aspirin induced or described as an eosinophilic type of asthma [ 15 ]. When evaluating a patient with suspected asthma; history taking should focus on aspects such as the presence of symptoms, the pattern and frequency of such symptoms, what are some precipitating factors and the existence of atopy, among other risk factors. There are some physical examination findings ( **Figure 6** ), which increase the likelihood of asthma and include the presence of nasal secretions, nasal swelling, and presence of nasal polyps, which are common in patients with allergic asthma. Cough may be dry or productive, where sputum have a pale yellowish discoloration which is secondary to presence of eosinophils and usually worsen at night. Chest tightness is most like band like, with feeling of heavy chest compression. Atopic dermatitis and eczemas are the most common skin manifestation noted in patients with asthma.

 Chest examination may be normal between exacerbation, but during exacerbations there is limited airflow to cause wheezing, for which patients present with reduced breath sounds with prolonged expiration. Tripod position, use of accessory muscle of respiration and prolonged expiration (defined as decreased I: E ratio), are also noted during acute asthma exacerbations.

 There are several risk factors that are involved in the development of asthma and many of them are an interaction between both host and environmental factors. Several studies have identified genetic factors that predispose to asthma, but these interact with other environmental factors such as indoor allergens such as furred

#### **Figure 6.**

 *Common clinical features in difficult to treat asthma that relates to environmental and occupational exposures.* 

*Environmental and Occupational Factors; Contribution and Perspectives on Difficult to Treat… DOI: http://dx.doi.org/10.5772/intechopen.108605*

animals, dusts, rodents, mold and cockroaches, as well as outdoor allergens as mols, pollen, air pollution, fumes, occupational exposure, and viral infections. History of tobacco smoking, second hand smoking exposure and commodities such as obesity, are also important risk factors. A personal history or family history of atopy may be present, characterized by seasonal allergies, atopic dermatitis and conjunctivitis, is common. There are cases, where patients have sensitivity to aspirin, presence of nasal polyps and wheezing, commonly known as the "asthmatic triad". This specific asthma symptoms, can be further recognized and attributed to specific situations were an environmental or occupation factors is present. When dealing with environmental exposures one of the most common symptoms that patients will be expressing is sneezing, rhinitis, and shortness of breath that can be divided in to dry cough or chest tightness, that most of the time will lead to increase in asthma regimens. Most of the patients will have some kind of relieve when they completely avoid this exposures such as vacation times or time off at home, however most of the environmental factors present at work place environmental can be found at home.

#### **2.1 Diagnostic modalities**

Establishing the diagnosis of asthma requires evaluation with a pulmonary function test (PFT). Other test such as laboratory testing, chest x-rays and allergy testing are mainly used to identify the different phenotypes of asthma. Arterial blood gas examination is also use and help to identify those patients with respiratory acidosis or increase CO2 that are in impending respiratory failure and may require mechanical ventilation as part of their treatment. In severe exacerbation, patients may present with hypoxemia and increase alveolar to arterial oxygen gradient, requiring oxygen supplementation. The PFT determines the degree and reversibility of airflow obstruction. Spirometry prior and after bronchodilation therapy is used for proper evaluation of the forced expiratory volume in one second (FEV1, forced vital capacity (FVC) and FEV1/FVC ratio. These measurements aid in the determination of airflow obstruction and reversibility of the disease. Airflow obstruction is defined as a ratio of FEV1 to FVC less than 0.70 or less than lower limit of normal. Severity of the disease is determined by the degree of reduction in the FEV1 below normal values. Patient with a FEV1 more than 70% predicted are classify as mild obstruction, a FEV1 between 50 to 69% predicted have moderate obstruction and FEV1 less than 50% predicted have severe obstruction [16]. Reversibility is determined by an increase of 12% or more than 200 ml in the FEV1 or FVC after the use of inhaled bronchodilators. Diagnostic modalities such as peak flow meters can be used when specific environmental factors are present and it will lead to variability of flow at this situations, and disappearance of this reduction in flows when not at contact.

In patients where spirometry is not diagnostic, a bronchial provocation testing with methacholine or histamine is used to diagnose asthma. A positive testing is defined as a reduction in the FEV1 of 20% or more or 8 mg/ml. When patient have a negative result there is 95% chance of ruling out asthma as the diagnosis, due to this testing high negative predictive value. Another important tool that is used to monitor or quantify asthma severity is the Peak Flow. This serves as an objective tool used by clinicians and patients, to monitor flow variability and response to medical treatment. Peak flow depends on patient's height, weight and age but these are poorly standardized markers and measurement tends to vary as the day goes by. It is recommended that peak flow be used early in the morning after the use of bronchodilator therapy and in the afternoon. Patients that have a change of 20% or more from morning

measurements or from day to day, suggest that patients have an uncontrolled asthma and required medication adjustments. If there is less than 200 L/min then there is severe airflow obstruction [16].

Imaging studies are not routinely done, as most patient have normal chest X ray. Some patients may show hyperinflation, diminished peripheral vasculature and bronchial thickening. Chest imaging are usually done when other superimpose conditions are suspected such as pneumonia or pneumothorax are suspected. Skin testing in combination with serum IgE leves is sometimes used together to better evaluate patients with atopy and aeroallergens, which in some cases will provide clinically relevant information. Absolute eosinophil count is requested for evaluation of eosinophilic asthma which benefit from anti IlL5 monotherapy. Finally, evaluation of the paranasal sinus and esophagus is done to rule out gastroesophageal reflux disease or paranasal sinus disease as a possible cause for refractory or persistent asthma.
