Kevin Keller

University of Nebraska Medical Center - College of Medicine
Omaha, Nebraska

Instructor(s): Von Essen, Susanna; Thiele, Geoffrey
Subject area: Health / Medicine
Department: Medicine
Level: Undergraduate Medical
Learning objective: Develop Group Skills, Develop Individual Skills, Provide Information
Teaching style: Group Activity, In-class Activity

Please note that the copyright for this course project is retained by the instructor.



This Problem Based Learning Case is presented to first and second year medical students at the University of Nebraska College of Medicine. The students work through an actual case presentation of an environmental health problem. The instructor guides the discussion as the students work through the case. In an interactive question/discussion format, needed information is provided to the students to work through the differential diagnosis and arrive at the appropriate conclusion. This case focuses on occupational asthma.


FACILITATOR'S GUIDE

Major Subject Areas

1. Common causes of occupational asthma.
2. Signs and symptoms of asthma.
3. Mechanisms of airway inflammation in allergic rhinitis and asthma (including the differences between the early and late reactions in asthma).
4. Mechanisms of action of medications that treat airway inflammation in allergic rhinitis and asthma.

Minor Subject Areas

1. Occupational history.
2. Differences between occupational asthma and asthma with other etiologies.
3. Pulmonary effects of cigarette smoking.
4. Spirometry and measurement of the diffusing capacity and how this is useful in assessing the patient with chronic cough.
5. How to use a Material Safety Data Sheet.

Learning Objectives

1. Explain the pathophysiology of airway inflammation associated with asthma and allergic rhinitis.
2. Discuss the signs and symptoms of asthma, including those of the early and late reactions to stimuli that trigger asthma.
3. Discuss the differential diagnosis of chronic cough.
4. Explain how to recognize and treat occupational asthma Caused by both low and high molecular weight compounds.
5. Explain the mechanism of action of drugs used to manage asthma.
6. Describe the manifestations and mechanisms of airway disease related to cigarette smoking.
7. Explain the role of IgE antibodies in asthma.
8. Describe how the immune system-is activated in asthma. Include the role of each of the following in your discussion: antigen presenting cells, MHC molecules, cytokines. T helper cells, T cytotoxic cells, basophils and mast cells and cross linking of Fc receptors by IgE antibody.

Case Summary

Kevin Keller is a 26 year old man who comes to the outpatient clinic complaining of a cough associated with wheezing, chest tightness and exertional dyspnea. The history and pulmonary function tests suggest a late asthmatic reaction. These symptoms have been present for 3 months. They are much improved after time away from work. His chest exam in clinic is unremarkable, which is not uncommon in asthma. His Spirometry shows only mild airway obstruction. However, he has a large fall in peak expiratory flow after the end of a workday spent painting cars at the auto body shop where he works as well as at night when he is most symptomatic. His asthma symptoms decrease when he is away from work and his peak expiratory flow improves. The history, spirometry and peak flow results are all consistent with the presence of occupational asthma. It is of note that patients with asthma may develop symptoms from exposures to aerosols of various kinds, including those containing substances to which they are not allergic. This irritant effect must be considered when looking for cause and effect relationships in occupational exposures. The exposure to automobile paint hardener containing isocyanates, a common cause of occupational asthma, and the fact that the asthma started after doing this type of work for several years support the hypothesis that the paint exposure caused the asthma. The Material Safety Data sheets for the paints and hardeners he uses in his work can be obtained from Mr. Keller's employer.

His history is also notable for the presence of allergic rhinitis. This problem is a known risk factor for occupational asthma. It is also a risk factor for developing asthma not related to occupational exposures. Thus, it was very important to perform peak flow measurements before! during and after days spent painting cars to demonstrate the connection between this exposure and his symptoms.

The airway inflammation in asthma is characterized by increased numbers of eosinophils, mast cells and Iymphocytes in the airway wall. These cells release a variety of mediators of inflammation that cause bronchoconstriction, edema and mucus secretion, including histamine, leukotrienes, prostaglandins, Substance P. platelet activating factor, Interleukin-8, proteases, and cytokines such as GM-CSF, TNF-alpha, Interleukin-3, 4, 5 and 10. The treatment of occupational asthma consists of ending the causative exposure as well as management with anti-inflammatory and bronchodilator medications used for asthma in general.

References:

1. Bigby TD and Wasserman Sl: Asthma. In Stein JH, editor: Internal Medicine, 4th ed. St. Louis, 1994 Mosby.
2. Chan-Yeung, M and Malo J-L. Occupational asthma. The New England Journal of Medicine 333:107, 1995.
3. Asthma: The Important Questions, Part 3. Supplement to: American Journal of Respiratory and Critical Care Medicine 153:S2, 1996.
4. Malo J-L and Cartier A. Occupational asthma. In Harber P. Schenker M and Balmes J editors: Occupational and Environmental Respiratory Disease, 1st ed. St. Louis, 1996 Mosby.
5. Immunology, 4th edition. Editors: Roitt IM, Brostoff J and Male D. Mosby. Philadelphia, PA 1996.
6. Clinical Immunology. Editors: Brostoff J. Scadding GK, Male D and Roitt M. Gower Medical Publishing, New York NY 1991.


SESSION 1

Initial Presentation

Kevin Keller is a 26 year old man who comes to your clinic on Monday morning complaining of cough for the past 3 months, which is getting worse.

Questions:
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The cough is now waking him up at night. He also experiences chest tightness at times. Sometimes he feels short of breath when he is working. His wife, a nurse, told him he should see a doctor and she came to this clinic appointment with him.

What other questions do you need to ask this patient?
1. Has he ever had a pulmonary assessment by a physician?
2. Has he ever been told he has asthma?
3. Does he smoke cigarettes?
4. What exposures occur at work?
5. What environmental exposures occur during his free time?

What are the initial learning issues?
1. Determining what exposures in the patient's workplace or elsewhere could be causing or exacerbating his symptoms.
2. Finding out how to obtain objective evidence of respiratory impairment (chest X-ray, pulmonary function tests etc.) that will help decide a course of action.
3. What circadian rhythm effects account for the symptoms being worse at night?


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Mr. Keller first noticed the cough at the time of a severe cold several months ago. For a time he used Primatene Mist, which helped his symptoms.

How does it help to know that Primatine Mist helped him?
Primatine Mist contains epinephrine 5.5 milligrams per ml . This active ingredient reduces bronchial muscle spasm in patients with asthma. It is recommended only for short term use in patients who have been diagnosed with asthma. It is important that patients with other health conditions, such as heart disease, consult with a physician before using the product. If the patient's symptoms do not improve after 20 minutes, medical attention must be sought. Mr. Keller should probably not continue using Primatine Mist as it is only temporarily relieving his symptoms and he needs a full evaluation.


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Later In Clinic Visit

Mr. Keller has been employed at Goodman's Auto Body Repair for the past 3 years. He has been on light duty for 1 week because of a hand injury (working in the shop's office, answering the telephone while the secretary is on vacation) and the cough has been less severe during this time.

Mr. Keller's cough is sometimes productive of thick, white sputum. The cough is somewhat better since he has been on light duty due to injury. He noticed the same thing after taking a vacation this summer.


What further questions would you ask?
1. Does the patient have any history or symptoms of heart disease?
2. Has he ever had wheezing, particularly with a cold?
3. What are his job duties at Goodman Auto Body? What exposure in auto body shops causes asthma?

How do you interpret the following:
1. The history of improvement after time away from work?
2. The improvement while on light duty?


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He has not coughed up any blood. His weight has not changed. He has had no fevers or night sweats. He has not been to the doctor in several years and is not aware of other medical problems except for hypertension identified when he went to the Red Cross to donate blood. He takes no prescription medications. He smokes 1.5 packs of cigarettes per day, which he has done since age 15. He drinks 2 cans of beer every night after work and more on weekends. Fishing, hunting and riding his motorcycle are his weekend pastimes. He lives in Bennington and is a member of the volunteer fire department there. His family has a dog and a cat.

1. What is the importance of the smoking history?
2. What about his hypertension?
3. What is your differential diagnosis at this time?
4. What additional information would you like to obtain?

END OF SESSION 1

Wrap-Up
Hand out summary of this session.

1. Have a student summarize the case.
2. Review and prioritize learning issues; discuss possible resources.

Review Group Process

1. Did everyone get a chance to participate?
2. Did someone dominate the discussion?
3. Did someone not contribute or participate as fully as they could have?
4. What actions contributed to effective group process?
5. How can we do a better job next time?

Tasks For Next Session

1. Summarize/review case.
2. Review and discuss learning issues.
3 List and critique resources used.
4. Update hypotheses (add, delete, and rank) and inquiry/management decisions.


SESSION 2

1. Summarize / review case.
2. Review and discuss learning issues. Instead of asking for volunteers to discuss learning issues, randomly ask different students to address the learning issues. This insures that everyone is prepared to discuss all major learning issues and not one issue for which they are especially prepared.
3. List and critique resources used. During session 2 or 3, each student should turn in a relevant journal article. Please review the articles. make comments, and return them to students. You may also ask students to summarize the articles.
4. Update hypotheses (add delete. and rank) and inquiry / management decisions.

History

His job at the auto body shop consists of repainting cars. Mr. Keller's history is notable for having served in the Army in the Persian Gulf War. He was exposed to smoke from the oil fires at that time. He has worked at several jobs, including employment at Aksarben Beef, on the production line packing cereal boxes at the Kellogg cereal plant and as a delivery truck driver.


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1. What is the significance of his past employment record?
Previous exposures may contribute to his present problems. The primary components of an occupational and environmental exposure history includes understanding the job process, not just noting the job title; addressing potential off the job environmental exposures, including those from non-salaried vocations, household work, and the ambient air; assessing the degree of exposure, even if indirectly, without the benefit of industrial hygiene monitoring; evaluating temporal and dose response associations between exposure and illness; delineating protective measures used; gauging general hygienic conditions; and finally, ruling out specific exposures of importance.

2. What is the importance of a good physical examination for this patient?
Few occupational or environmental diseases present specific clinical findings. The physician suspecting the presence of occupational or environmental respiratory disease should, none the less, perform a complete physical examination rather than focus narrowly on possible findings suggested by the exposure history . Relevant non exposure related disease may otherwise be missed. For example, careful ausculatation of the heart may reveal evidence of valvular heart disease that turns out to be a more important cause of the patients dyspnea and exercise intolerance than his or her past asbestos exposure. The general appearance should be noted, especially for evidence of respiratory distress and chronic debilitating disease, such as end stage lung disease or cancer. If the patient comes to the examination straight from work, it is wise to look for evidence of the level of workplace exposure, such as dust on face and clothes or flash bums from welding. Tobacco stained fingers and the presence of a cigarette pack in a shirt pocket are telling clues that a patient who claims that he or she has quit smoking is not telling the truth. The degree of difficulty breathing while speaking long sentences and walking on level ground or climbing stairs can be helpful in determining the level of respiratory impairment. Hoarseness may be a sign of laryngeal inflammation or tumor. Involuntary coughing during the examination suggests that respiratory tract irritation is persistent. In addition to respiratory rate, the blood pressure and pulse should be measured as signs of possible cardiovascular disease.

The head, eye, ear, nose, and throat examination can provide important evidence of mucosal inflammation when exposure to water soluble respiratory tract irritants has occurred. Conjunctival erythema, sinus tenderness, nasal mucosal erythema and edema, rhinorea and conjunctival erythema are all signs consistent with Instant induced injury. The presence of facial bums, either thermal or chemical. increases the probability of lower respiratory tract injury. Nasal ulcers can be caused by excessive exposure to chromium salts, and nasal polyps are a sure sign of allergic rhinitis which may be occupational in origin. When a history of tong term occupational exposure to wood dust, formaldehyde, nickel compounds or asbestos has been elicited, the examination should be directed toward the possibility of head and neck tumors. The examination of the chest in patients with suspected occupational and environmental lung disease need be no different than in parents with other types of lung disease. The examination should include inspection, percussion and auscultation. Hyperexpansion of the chest suggests the presence of emphysema, which is more likely to be caused by cigarette smoking than occupational exposure. Chest percussion may provide evidence of lobar consolidation, pleural effusion or a large tumor mass. Any wheezing, rhonchi or crackles should be described as to intensity, location and phase of the respiratory cycle. The presence of any of these is presumptive evidence of respiratory tract disease. Wheezing is produced by turbulent flow through an airway. Inspiratory wheezing suggests upper airway obstruction and should prompt a more thorough examination of the neck for evidence of stridor. Expiratory wheezing usually indicates thoracic bronchial constriction. Unilateral expiratory wheezing in a parent with exposure to a lung carcinogen is a finding that warrants further work-up for an obstructing tumor. The presence of rhonchi suggest increased airway secretions and is sign of bronchitis.

The physical examination may be helpful if abnormal, but one should remember that it is relatively insensitive for detection of mild respiratory tract injury. Pulmonary function and chest imaging studies may have greater sensitivity. In general, the physical examination is probably more useful for the detection of signs of non-respiratory organ system dysfunction that could be contributing to disability, such as left ventricular failure, than in characterizing a level of respiratory impairment. An exception would be when there is evidence of end stage lung disease, such as cyanosis or right ventricular failure. The linkage between an occupational or environmental risk factor and a specific respiratory disorder is often difficult to establish because presentation of occupationally or environmentally caused illness is rarely pathognomonic. It is first necessary to have a high index of suspicion that occupational or environmental risk factors may be playing a role in the patient's illness. A careful but targeted history may then provide appropriate evidence to support the diagnosis of an exposure related respiratory disorder. The approach to such a history will allow occupational and environmental respiratory disease to be ruled out or in in most cases. Finally, a through physical examination is essential, not only to confirm the suspected diagnosis but to exclude non exposure related or even extra pulmonary etiologies.

The patient gets "hay fever' every fall. He has not seen a physician for general health care since leaving the military at age 21.

One of his 3 sons has asthma and another one has "hay fever". He thinks that one of his uncles is disabled because of "lung trouble" and uses supplemental oxygen. His father died of lung cancer and his mother has diabetes.

His home environment is notable for the presence of a dog and a cat. The basement of his home tends to be damp and sometimes there is mold visible on the walls.


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What further information would you like?
1. Spirometry results? Chest X-ray findings?
2. Results of monitoring peak expiratory flow rates before and after a work shift each day for two weeks after he returns to work?
3. Does he need skin testing for allergies?
4. How can the Material Safety Data Sheet for the paint he uses help you? How would you obtain such a document?

The OSHAct requires chemical manufacturers to create MSDS for each chemical they produce and employers who use these chemicals must retain these MSDS in the workplace. Required information includes chemical and common names, physical, safety, and health hazard data, exposure limits, precautions for safe handling and use, generally applicable control measures, and emergency and first aid procedures. Individual employers are required to provide employees with information on the chemical agents used in their own workplaces.

Physical Examination

Height = 70 inches and weight = 76 kg.

Vital signs: Temperature = 98.8, respirations = 14, pulse = 80, BP = 150/92.

HEENT exam: Nasal mucosa, pharynx, tympanic membranes normal in appearance. Two palpable lymph nodes in the neck which are less than 1 cm in diameter, not tender and not fixed.

Lungs: Clear to auscultation.

Heart: There is a Grade l/VI blowing, mid-systolic murmur best heard at the left lower sternal border. There are no gallops.

Skin: Healing blisters from sunburn on shoulders, face and arms.

Musculoskeletal: Right hand wrapped in a bandage.

Abdomen: Normal.

Genitorectal: Normal.

Neurologic: Normal.

1. How do you explain the pulmonary findings? How could the heart murmur be linked to the patient's symptoms?
2. What further tests need to be ordered at this time? CXR Spirometry
3. What are the health care maintenance needs at this time? Does he need follow-up for this blood pressure?
4. What laboratory tests would you request and why?
5. How are Material Safety Data Sheets helpful and where do you find them?
6. How would you treat the cough and what are the reasons for your choices?
7. What further information would be helpful? a. Does anyone else at work have these symptoms? b. What is thought to be the cause of his son's asthma?
8. What is your differential diagnosis at this time?

END OF SESSION 2

Wrap-Up
Hand out summary of this session.

1. Have a student summarize the case.
2. Review and prioritize learning issues; discuss possible resources.

Review Group Process

1. Did everyone get a chance to participate?
2. Did someone dominate the discussion?
3. Did someone not contribute or participate as fully as they could have?
4. What actions contributed to effective group process?
5. How can we do a better job next time?

Tasks For Next Session

1. Summarize/review case.
2. Review and discuss learning issues.
3. List and critique resources used.
4. Update hypotheses (add, delete, and rank) and inquiry/management decisions.


SESSION 3

1. Summarize / review case.
2. Review and discuss learning issues. Instead of asking for volunteers to discuss learning issues, randomly ask different students to address the learning issues. This insures that everyone is prepared to discuss all major learning issues and not one issue for which they are especially prepared.
3. List and critique resources used. During session 2 or 3, each student should turn in a relevant journal article. Please review the articles. make comments, and return them to students. You may also ask students to summarize the articles.
4. Update hypotheses (add, delete, and rank) and inquiry / management decisions.

Initial Laboratory Information

The chest X-ray is normal.

Spirometry is as follows: (See Appendix 1 )

Handout appendix 1

How do you interpret the Spirometry results?


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Subsequent Laboratory information

The peak expiratory flow record from when he returned to work: (See Appendix 2)

How do you interpret these results?

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Handout Appendix 2

1. What are the major hypotheses that should be considered?
a. Occupational asthma
b. Allergic asthma
c. Post-viral cough with bronchospasm
d. Valvular heart disease with cardiogenic pulmonary edema
e. Reactive Airways Dysfunction Syndrome (seen after smoke inhalation, a single heavy exposure to fumes of various kinds)

2. What is this patient's diagnosis and how did you make that decision?

3. What is the cost of the Spirometry? The chest X-ray? The peak flow meter?

4. Why are some tests used in asthma research not helpful here, such as a total eosinophil count, measurement of a serum IgE level, bronchoscopy with bronchoalveolar lavage and bronchial wall biopsy and examination of sputum induced by inhalation of hypertonic saline?

Follow-Up Information

The patient brings in the Material Safety Data Sheet for DAU2, a paint hardener (see Appendix 3). He got this information from the shop manager, who serves as the safety officer for the business. The shop manager told him that this substance may be the cause of his breathing problems because it affected the man who held the job before him in this way.

You discuss treatment and prevention options with Mr. Keller.


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1. What are your recommendations to the patient at this time? Change jobs.

2. How do you treat his symptoms?

3. What is his progress?

You recommend that the patient should change jobs because of the link between the isocyanate exposure and his asthma. He takes a job in the warehouse at the Nebraska Furniture Mart. You see him back in clinic in two months. At that time he has been able to stop using the beta-agonist inhaler and the corticosteroid inhaler therapy you prescribed after you made the diagnosis. He no longer has asthma symptoms and his repeat Spirometry is normal.


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1. Major learning issues all should research:
a. Pathologic changes in the airways in asthma - changes in cell numbers and types, epithelial damage and subepithelial fibrosis.
b. Inflammatory mediators in asthma.
c. Assessment of a patient with possible occupational asthma.
d. Pulmonary function test changes in asthma.
e. Mechanism of action of beta-agonist drugs in asthma.
f. Medical, financial and social consequences of untreated occupational asthma.

2. Minor learning issues:
a. Mechanisms of action of drugs used to treat asthma.
b. Effects of cigarette smoking on the airways.
c. Effects of viral infections on the airways.
d. Pulmonary signs and symptoms of heart disease.


Learning Objectives

1. Understand the pathophysiology of airway inflammation associated with asthma and allergic rhinitis.
2. Be able to discuss the signs and symptoms of asthma, including those of the early and late reactions to stimuli that trigger asthma.
3. Be able to discuss the differential diagnosis of chronic cough.
4. Understand how to recognize and treat occupational asthma caused by both low and high molecular weight compounds.
5. Be familiar with the mechanism of action of drugs used to manage asthma.
6. Understand the manifestations and mechanisms of airway disease related to cigarette smoking.
7. Become familiar with the role of IgE antibodies in asthma.
8. Describe how the immune system is activated in asthma. Include the following in your discussion: antigen presenting cells, MHC molecules, cytokines, T helper cells, T cytotoxic cells, basophils and mast cells and cross linking of Fc receptors by IgE antibody.

Wrap-Up

Handout Learning Objectives.
Hand out summary of this session.
Have a student summarize the case.
Review and prioritize learning issues, discuss possible resources.

Review Group Process

1. Did everyone get a chance to participate?
2. Did someone dominate the discussion?
3. Did someone not contribute or participate as fully as they could have?
4. What actions contributed to effective group process?
5. How can we do a better job next time?

Summary And Integration Of Learning

1. Review objectives for this case.
2. What did we learn?
3. Could we have gone through the case more efficiently?

PBL Written Evaluation

Appendices and Handouts
Appendix 1: UNMC Pulmonary Medicine Section-Pulmonary Physiology Lab Pulmonary Function Plot
Appendix 2: Graph of Peak Expiratory Flow Rates (L/min) per day
Appendix 3: Material Safety Data Sheet for DAU2
Handout: Taking an occupational and environmental history: key questions in a targeted interview




This document was last modified on 06/14/2000 03:07:54 PM



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