Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Asthma


Related Terms

  • Allergic Asthma
  • Asthmatic Bronchitis
  • Bronchial Asthma
  • Catarrhal Asthma
  • Chronic Desquamating Eosinophilic Bronchitis
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Exercise Induced Asthma (EIA)
  • Exercise Induced Bronchospasm (EIB)
  • Hyper-reactive Airway Disease
  • Reactive Airway Disease (RAD)

Differential Diagnosis

Specialists

  • Allergist/Immunologist
  • Critical Care Internist
  • Emergency Medicine Physician
  • Pulmonologist

Comorbid Conditions

  • Allergic rhinitis
  • Gastroesophageal reflux

Factors Influencing Duration

The factors most likely to influence disability are the severity of the attack, the development of complications, whether episodes are acute or part of a chronic condition, any underlying chronic medical conditions, the individual's type of work, and most importantly, the individual’s compliance with prescribed treatment.

Overall, the chronic, well-managed, mild to moderately severe asthmatic may experience very few days lost from work due to the disease. Smokers and individuals regularly exposed to known allergens are at greater risk for severe asthma with complications and increased duration.

Medical Codes

ICD-9-CM:
493 - Asthma
493.0 - Asthma, Extrinsic
493.00 - Asthma, Extrinsic, without Mention of Status Asthmaticus
493.01 - Asthma, Extrinsic, with Status Asthmaticus
493.02 - Asthma, Extrinsic, with (Acute) Exacerbation
493.1 - Asthma, Intrinsic
493.10 - Asthma, Intrinsic, Unspecified
493.11 - Asthma, Intrinsic, with Status Asthmaticus
493.12 - Asthma, Intrinsic, with (Acute) Exacerbation
493.2 - Asthma, Chronic Obstructive
493.20 - Asthma, Chronic Obstructive, Unspecified
493.21 - Asthma, Chronic Obstructive, with Status Asthmaticus
493.22 - Asthma, Chronic Obstructive, with (Acute) Exacerbation
493.81 - Exercise Induced Bronchospasm
493.82 - Cough Variant Asthma
493.9 - Asthma, Unspecified
493.90 - Asthma, Unspecified, Unspecified
493.91 - Asthma, Unspecified, with Status Asthmaticus
493.92 - Asthma, Unspecified, with (Acute) Exacerbation

Overview

Asthma is a chronic inflammatory disorder of the airways in which airflow in and out of the lungs may be blocked by bronchial muscle constriction (bronchospasm), swelling of airway tissue, and excess mucus. Asthma is characterized by acute episodes of obstructed breathing that occur with the narrowing of breathing passages, making it difficult to inhale but even more difficult to exhale. With mild asthma, the airways are relatively normal between attacks. In more severe asthma, there is some degree of constant airway constriction, with additional narrowing that occurs during an acute attack. Typical symptoms include wheezing, shortness of breath, chest tightness, and coughing.

Many types of cells and cellular elements are responsible for the stimulation of smooth muscle and the chronic inflammatory changes in the airway that are characteristic of asthma, including mast cells, eosinophils, T lymphocytes, macrophages, and neutrophils. Production of these cells by the immune system of individuals with asthma is an exaggerated (hyper-reactive) response triggered by various stimuli in the environment; individuals who do not have asthma are not affected in the same way. Individuals with asthma may have recurrent episodes of inflamed, narrowed airways when exposed to certain environmental triggers. Asthma attacks can be associated with varying degrees of airflow obstruction. Acute or chronic inflammation may also result in increasing bronchial responsiveness to triggers. The degree of hyper-responsiveness usually correlates directly with the severity of asthma.

Asthma symptoms can be triggered by allergens or irritants, upper respiratory tract infections (URI), stomach acid flowing back up the esophagus (gastroesophageal reflux disease [GERD]), certain medications or foods, anxiety, and exercise (exercise-induced asthma [EIA] or exercise-induced bronchospasm [EIB]). Individuals with allergic rhinitis (hay fever) are more likely to develop allergic asthma. Symptoms of asthma and allergic rhinitis can be triggered by seasonal or year-round allergens, which can include airborne pollens and molds, animal dander (dead skin flakes), house dust mite and cockroach droppings, and indoor molds.

Occupational asthma is generally defined as a respiratory disorder directly related to inhalation of fumes, gases, dust, enzymes, metals, animal proteins, fungi, pollens, pharmaceutical agents, or other potentially harmful substances while on the job. With occupational asthma, symptoms of asthma may develop for the first time in a previously healthy worker, or pre-existing asthma may be aggravated by exposure within the workplace. Occupational asthma has become the most prevalent work-related lung disease in developed countries.

Incidence and Prevalence: The incidence of asthma is highest among the very young and very old; most cases are diagnosed before age 18. About 22 million people in the US have asthma; about 6 million of them are children under age 18 (Morris). Approximately 1.8 million emergency room visits annually involve asthma episodes, with 500,000 hospitalizations and 5,000 deaths (Morris).

Internationally, asthma prevalence in industrialized countries ranges from 2% to 10% (Morris); rates vary from 0.7% in Tokyo to a high of 6.3% in the United Kingdom, with an average of 5%; rates in nonindustrialized countries are lower (Canaday). Severe asthma affects about 300 million people worldwide (Morris). Both the prevalence and severity of disease appear to be increasing, particularly in children under age 6. This has been attributed to urbanization, air pollution, passive smoking, and increased exposure to environmental allergens.

Source: Medical Disability Advisor



Causation and Known Risk Factors

Susceptibility to allergic asthma appears to be an inherited trait; genetic factors significantly influence predisposition for developing any type of asthma, but environmental factors have a greater direct influence on the onset of the disease (Morris). Although asthma can begin at any age, most cases begin before the age of 25. Premature birth increases the risk of developing asthma. More boys have asthma than girls (male to female ratio 2:1) until puberty, when the prevalence becomes equal; in adulthood, more women have asthma than men. Asthma occurs in all races; blacks have more asthma attacks and are more likely than whites to be hospitalized for asthma attacks and to die from asthma ("Asthma"). Allergic rhinitis (hay fever) increases the risk of developing allergic asthma.

Smoking decreases the effectiveness of medications and worsens the overall asthmatic condition. Risk factors for asthma deaths include being older than 40, increased levels of blood eosinophils, cigarette smoking (more than 20 packs a year), and having a forced expiratory volume (FEV) of 40% to 69% (Morris).

Source: Medical Disability Advisor



Diagnosis

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.

Source: Medical Disability Advisor



Treatment

Acute asthma is treated with bronchodilator inhalants and oxygen. Intravenous (IV) muscle relaxants and steroids may also be needed. If the attack is severe and prolonged, the individual will be admitted to the hospital for intensive treatment because respiratory failure and death can occur. In-patient treatment might require a positive-pressure oxygen mask or mechanical ventilation (respirator).

Treatment of chronic asthma includes inhaled bronchodilators (sympathomimetics and parasympatholytics), anti-inflammatory medications (inhaled or systemic steroids, inhaled cromolyns, and leukotriene modifiers), theophyllines (less commonly), and decreased exposure to causative agents. The goal with these medications is to stabilize lung function and decrease the likelihood of developing acute asthma symptoms. Newer immunomodulating drugs are also available and show promise in the management of moderate to severe persistent asthma.

Medications for control of chronic asthma fall into 2 categories: quick relief (reliever) medications or long-term control (controller) medications. Reliever medications for asthma exacerbations include short-acting beta-agonists that work by relaxing the smooth muscles surrounding the bronchi and bronchioles, anticholinergics (for severe exacerbations), and systemic corticosteroids.

Bronchodilators are generally used as asthma "rescue medications" to relieve coughing, wheezing, shortness of breath, and difficulty in breathing. They can be short-acting drugs or long-term controller drugs and may also be used before exposure to a known asthma trigger to decrease any potential bronchospasm. They are the primary medication for EIA, usually provided in a metered-dose inhaler (MDI).

Anti-inflammatory agents such as corticosteroids reduce asthma symptoms. Inhaled corticosteroids are the cornerstone of asthma treatment because they act to reduce inflammation, which is thought to decrease disease progression. Many of the cells that cause airway inflammation are known to produce potent chemicals within the body called leukotrienes. Leukotrienes are responsible for contracting the smooth muscles of the airway, increasing fluid leakage from blood vessels in the lung, and promoting inflammation by attracting other inflammatory cells into the airways. Oral anti-leukotriene medications help fight the inflammatory response and are used to treat chronic asthma.

A recombinant DNA-derived humanized immunoglobulin G monoclonal antibody is a newer drug that binds to the excess IgE on mast cell and basophil surfaces, reducing the release of mediators that cause the allergic response.

Antihistamines may be prescribed to relieve or prevent the symptoms of allergic rhinitis (hay fever) and other allergies. Decongestants are used to treat nasal congestion and other symptoms by shrinking blood vessels, thereby decreasing the amount of fluid that leaks out and reducing nasal congestion.

Aggressive treatment of any respiratory or pulmonary infections associated with an asthma exacerbation is recommended, along with immunization against influenza and pneumococcal pneumonia.

Source: Medical Disability Advisor



Prognosis

The outcome in asthma is variable. Nearly 20% of individuals with asthma have some limitation in their daily lives due to the disease. A mild asthmatic attack may be treated easily with an extra dose of inhaled bronchodilator. A severe asthmatic attack might lead to severe, prolonged asthma, hospitalization, and multiple complications. If the individual's airways remain chronically inflamed, permanent disability may occur. The keys to a good outcome are daily peak flow monitoring, strict compliance with medications, and avoidance of known triggers.

Source: Medical Disability Advisor



Complications

Free air or gas within the pleural cavity (pneumothorax) or the abnormal presence of air in tissues that separate parts of the lung cavity (pneumomediastinum) can develop during severe asthma attacks, especially if the individual requires mechanical ventilation. A severe asthma attack that does not respond to treatment can lead to prolonged contraction (bronchospasm) of smooth muscles (status asthmaticus) and may be followed by respiratory failure and death. Individuals who have chronic pulmonary disease in addition to asthma will often have more severe and debilitating episodes of asthma.

Long-term oral steroid use by asthmatics can lead to blood chemistry disturbances, cataracts, osteoporosis, immunosuppression, and adrenal suppression. Over-treatment of asthma with bronchodilators may precipitate cardiac arrhythmia.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Avoiding fumes, gases, dust, extreme temperatures, and any other airway irritants known to trigger an attack is essential. Masks and/or respirators should be used when required. When asthma is triggered by exercise or exertion, the individual should first be given the opportunity to use preventive medication and, if that is ineffective, be reassigned to less strenuous duties.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Does individual complain of wheezing, coughing, chest tightness, and shortness of breath?
  • Is individual only able to speak in one- to two-word sentences?
  • Is individual restless and confused?
  • Are asthma attacks episodic?
  • Is individual asymptomatic between attacks?
  • Does individual have allergies, upper respiratory infection (URI), allergic rhinitis, or sinusitis?
  • Does individual exercise? Does exercise produce asthma symptoms?
  • Were symptoms worse through the workweek, improved on the weekend, and recurring when the worker returns to the job?
  • Does individual have occupational asthma?
  • Does individual smoke cigarettes at present or formerly?
  • Was there wheezing on exhalation or inhalation, or both?
  • Were other conditions present, such as tachypnea, tachycardia, using the accessory muscles in the neck to help breathing, cyanosis, or an exaggerated fall in systolic blood pressure during inhalation?
  • Were pulmonary function tests, pulse oximetry, and CBC done?
  • Did symptoms and physical signs respond positively to the administration of bronchodilators?
  • Was microscopic exam of sputum done?
  • Were arterial blood gases and an ECG done?
  • Does individual have an elevated IgE?
  • Was a methacholine challenge test done?
  • Are symptoms present only on the job?
  • Were qualitative and quantitative tests for possible air and gas triggers done?
  • Were conditions with similar symptoms ruled out?

Regarding treatment:

  • Was individual treated with bronchodilator inhalants and oxygen? Was it necessary to use IV muscle relaxants and steroids?
  • Was individual admitted to the hospital? To the intensive care unit?
  • Were an intubation and mechanical ventilation necessary?
  • Has individual been immunized against influenza and pneumococcal pneumonia?
  • Does individual use an inhaler to relieve exercise-induced asthma?

Regarding prognosis:

  • Is individual's employer able to accommodate any necessary restrictions?
  • Is individual able to avoid fumes, gases, dust, extreme temperatures, and any other airway irritants known to trigger an attack?
  • Does individual use masks or respirators when required?
  • Is asthma triggered by exercise or exertion? Does individual need sedentary work?
  • Does individual have any conditions that may affect the ability to recover?
  • Does individual have any complications such as pneumothorax, bronchospasm or status asthmaticus, or other chronic respiratory conditions?
  • Has individual been on long-term steroid use?
  • Is any underlying condition being managed effectively?

Source: Medical Disability Advisor



References

Cited

"Asthma." National Heart, Lung, and Blood Institute. Sep. 2008. Department of Health and Human Services. 5 Jan. 2009 <http://www.nhlbi.nih.gov/health/dci/Diseases/Asthma/Asthma_WhatIs.html>.

Canaday, Peter, and J. Collins. "Asthma." eMedicine. Eds. Jeffrey A. Miller, et al. 6 Dec. 2004. Medscape. 5 Jan. 2009 <http://emedicine.medscape.com/article/353436-overview>.

Morris, Michael J. "Asthma." eMedicine. Eds. Helen M. Hollingsworth, et al. 2 Apr. 2009. Medscape. 6 Apr. 2009 <http://emedicine.medscape.com/article/296301-overview>.

Source: Medical Disability Advisor






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