Find information on medical topics, symptoms, drugs, procedures, news and more, written for the health care professional. Asthma medications and merck is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea, chest tightness, cough, and wheezing. The diagnosis is based on history, physical examination, and pulmonary function tests.
Treatment involves controlling triggering factors and drug therapy, most commonly with inhaled beta-2 agonists and inhaled corticosteroids. Prognosis is good with treatment. The prevalence of asthma has increased continuously since the s, and the WHO estimates that million people worldwide are affected, asthma medications and merck. More than 25 million people in the US are affected. Asthma is one of the most common chronic diseases of childhood, affecting more than 6 million children in the US; it occurs more frequently in boys before puberty and in girls after puberty.
It also occurs more frequently in non-Hispanic blacks and Puerto Ricans. Despite its increasing prevalence, however, there has been a recent decline in mortality. In the US, about deaths occur annually as a result of asthma. However, the death rate is 2 to 3 times higher for blacks than for whites, asthma medications and merck.
Asthma is the leading cause of hospitalization for children and is the number one chronic condition causing elementary school absenteeism. Development of asthma is multifactorial and depends on the interactions among multiple susceptibility genes and environmental factors. Evidence clearly implicates household allergens eg, dust mite, cockroach, pet and other environmental allergens in disease development in older children and adults. Diets low in vitamins C asthma medications and merck E and in omega —3 fatty acids have been linked to asthma, as has obesity.
Asthma has also been linked to perinatal factors, such as young maternal age, poor maternal nutrition, prematurity, low birthweight, and lack of breastfeeding. On the other hand, endotoxin exposure early in life can induce tolerance and may be protective.
Air pollution is not definitively linked to disease development, although it may trigger exacerbations, asthma medications and merck. The role of childhood exposure to cigarette smoke is controversial, with some studies finding a contributory and some a protective effect. Asthma medications and merck and environmental components may interact, thereby determining the balance between T h 1 and T h 2 cell lineages.
Infants may be born with a predisposition toward proallergic and proinflammatory T h 2 immune responses, characterized by growth and activation of eosinophils and IgE production. Early childhood exposure to bacterial and viral infections and endotoxins may shift the body to T h 1 responses, which suppresses T h 2 cells and induce tolerance. Trends in developed countries toward smaller families with fewer children, cleaner indoor environments, and early use of vaccinations and antibiotics may deprive children of these T h 2-suppressing, tolerance-inducing exposures and may partly explain the continuous increase in asthma prevalence in developed countries the hygiene hypothesis.
Indoor exposures to nitrogen oxide and volatile organic compounds eg, from paints, solvents, adhesives are implicated in the development of RADS, a persistent asthma medications and merck syndrome in people with no history of asthma see Occupational Asthma.
RADS appears to be distinct from asthma and may be, on occasion, a form of environmental lung disease. However, RADS and asthma have many clinical similarities eg, asthma medications and merck, wheezing, dyspnea, coughand both may respond to corticosteroids. Hypertrophy of smooth muscle narrows the airways and increases reactivity to allergens, infections, irritants, parasympathetic cancer and sagittarius horoscope which causes release of pro-inflammatory neuropeptides, such as substance P, neurokinin A, and calcitonin gene-related peptideasthma medications and merck, and other triggers of bronchoconstriction.
Additional contributors to airway hyperreactivity include loss of asthma medications and merck of asthma medications and merck epithelium-derived relaxing factor, prostaglandin E 2 and loss of other substances called endopeptidases that metabolize endogenous bronchoconstrictors.
Mucus plugging and peripheral blood eosinophilia are additional classic findings in asthma and may be epiphenomena of airway inflammation. However, not all patients with asthma have eosinophilia. Infectious triggers in young children asthma medications and merck respiratory syncytial virusrhinovirus, and parainfluenza virus infection. In older children and adults, URIs particularly with rhinovirus and pneumonia are common infectious triggers, asthma medications and merck.
Exercise can be a trigger, especially in cold or dry environments. Inhaled irritants, such as asthma medications and merck pollution, cigarette smoke, asthma medications and merck, perfumes, and cleaning products, are often involved.
Emotions such as anxiety, anger, and excitement sometimes trigger exacerbations. GERD is a common trigger among some patients with asthma, possibly via esophageal acid-induced reflex bronchoconstriction or by microaspiration of acid.
However, treatment of asymptomatic GERD eg, with proton pump inhibitors does not seem to improve asthma control. Allergic rhinitis often coexists with asthma; it is unclear whether the two are different manifestations of the same allergic process or whether rhinitis is a discrete asthma trigger. In the presence of triggers, there is reversible airway narrowing and uneven lung ventilation.
Relative perfusion exceeds relative ventilation in lung regions distal to narrowed airways; thus, alveolar oxygen tensions fall and alveolar carbon dioxide tensions rise. Most patients can compensate by hyperventilating, but in severe exacerbations, diffuse bronchoconstriction causes severe gas trapping, and the respiratory muscles are put at a marked mechanical disadvantage so that the work of breathing increases.
Under these conditions, hypoxemia worsens and Pa co 2 rises. Respiratory acidosis and metabolic acidosis may result and, if left untreated, cause respiratory and cardiac arrest. Unlike hypertension eg, in which one parameter [BP] defines the severity of the disorder and the efficacy of treatmentasthma causes a number of clinical and testing abnormalities.
Also, unlike most types of hypertension, asthma manifestations typically wax and wane. Thus, monitoring and studying asthma requires a consistent terminology and defined benchmarks.
The term status asthmaticus describes severe, intense, prolonged bronchospasm that is erythromycin and flu medicine to treatment. Severity is the intrinsic intensity of the disease process ie, how bad it is—see Table: Severity can usually be assessed directly only before treatment is started, because patients who have responded well to treatment by definition have few symptoms, asthma medications and merck.
Asthma severity asthma medications and merck categorized as. It is important to asthma medications and merck that the severity category does not predict how serious an exacerbation a patient may have. For example, a patient who has mild asthma with long periods of no or mild symptoms and normal pulmonary function may have a severe, life-threatening exacerbation. Impairment is assessed over the previous 2—4 weeks, and risk is assessed over the past year. Severity is best classified at the first visit before a controller therapy is initiated not SABA or systemic corticosteroid bursts for symptoms or exacerbations.
In general, more frequent and intense exacerbations eg, requiring urgent, unscheduled care, hospitalization, or Asthma medications and merck admission indicate greater underlying disease severity. Expert Panel Report 3: Guidelines for the diagnosis and management of asthma—full report Control is the degree to which symptoms, impairments, and risks are minimized by asthma medications and merck. Control is the parameter assessed in patients receiving treatment.
The goal is for all patients to have well controlled asthma regardless of disease severity. Control is classified as. Severity and control are assessed in terms of patient impairment and risk see Table: Use of short-acting beta-2 asthma medications and merck for symptom control not prevention of exercise-induced asthma.
Additional factors to consider are progressive loss of lung function on pulmonary function tests, significant adverse effects, and severity and interval between exacerbations ie, one exacerbation requiring intubation or 2 hospitalizations within 1 mo may be considered very poor control. In general, more frequent and intense exacerbations eg, requiring urgent, unscheduled care, hospitalization, or ICU admission indicate poorer asthma control.
Impairment differs from severity by its emphasis on symptoms and functional limitations rather than the intrinsic intensity of the disease process. Impairment can be measured by spirometry, mainly forced expiratory volume in 1 sec FEV 1and the ratio of FEV 1 to forced vital capacity FVCbut is manifested as clinical features such as.
Risk refers to the likelihood of future exacerbations or decline in lung function and the risk of adverse drug effects.
Risk is assessed by long-term trends in spirometry and clinical features such as. Patients with mild asthma are typically asymptomatic between exacerbations, asthma medications and merck. Patients with more severe disease and those with exacerbations experience dyspnea, chest tightness, audible wheezing, and coughing. Coughing may be the only symptom in some patients cough-variant asthma.
Symptoms can follow a circadian rhythm and worsen during sleep, often around 4 am. Many patients with more severe asthma medications and merck waken during the night nocturnal asthma.
Calf pain and cephalexin expiratory phase of respiration is prolonged, with an inspiratory: Wheezes can be present through both phases or just on expiration, but patients with severe bronchoconstriction may have no audible wheezing because of markedly limited airflow.
Rarely, pneumothorax or pneumomediastinum is seen on chest x-ray. Symptoms and signs disappear between exacerbations, although soft wheezes may be audible during forced expiration at rest, or after exercise, asthma medications and merck, in some asymptomatic patients. Hyperinflation of the lungs may alter the chest wall in patients with long-standing uncontrolled asthma, causing a barrel-shaped thorax. All symptoms and signs are nonspecific, are reversible with timely treatment, and typically are brought on by exposure asthma medications and merck one or more triggers.
Diagnosis is based on history and physical examination and is confirmed with pulmonary function tests. Diagnosis of causes and the exclusion of other disorders that cause wheezing are also important. Asthma and COPD are sometimes easily confused; they cause similar symptoms and produce similar results on pulmonary function tests but differ in important biologic ways that are not always clinically apparent.
Asthma diabetices and vitamin k is difficult to control or refractory to commonly used controller therapies should be further evaluated for alternative causes of episodic wheezing, cough, and dyspnea such as allergic bronchopulmonary aspergillosisbronchiectasisor vocal cord dysfunction.
Patients suspected of having asthma should undergo pulmonary function testing to confirm and quantify the severity and reversibility of airway obstruction. Pulmonary function data quality is effort-dependent and requires patient education before the test. If it is safe to do so, bronchodilators should be stopped before the test: Spirometry should be done before and after inhalation of a short-acting bronchodilator. The FVC may also be decreased because of gas trapping, such that lung volume measurements may show an increase in the residual volume, the functional residual capacity, or both.
Flow-volume loops should also be reviewed to diagnose vocal cord dysfunction, a common cause of upper airway obstruction that mimics asthma. Provocative testing, asthma medications and merck, in which inhaled methacholine or alternatives, such as inhaled histamine, adenosineor bradykinin, or exercise testing is used to provoke bronchoconstriction, is indicated for patients suspected of having asthma who have normal findings on spirometry and flow-volume testing and for patients suspected of having cough-variant asthma, provided there are no contraindications.
DL co testing can help distinguish asthma from chronic obstructive pulmonary disease. Values are normal or elevated in asthma and usually reduced in COPD, particularly in patients with emphysema. A chest x-ray may help exclude some causes of asthma or alternative diagnoses, such as heart failure or pneumonia. The chest x-ray in asthma is usually normal but may show hyperinflation or segmental atelectasis, a sign of mucous plugging.
Infiltrates, especially those that come asthma medications and merck go and that are associated with findings of central bronchiectasis, suggest allergic bronchopulmonary aspergillosis. Allergy testing may be indicated for children whose history suggests allergic triggers particularly for allergic rhinitis because these children may benefit from immunotherapy.