Occupational Respiratory Disorder Case Study

University of Alberta
Edmonton, Alberta, Canada

Instructor(s): Guidotti, Tee L.
Subject area: Health / Medicine
Department: Faculty of Medicine
Level: Undergraduate Medical
Number of participants: 115
Duration of exercise: 1 hour
Learning objective: Develop Group 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 case study was used in an introductory, required course on occupational and environmental medicine for Phase III medical students at the University of Alberta Faculty of Medicine. This case study describes a 37 year old tile setter who developed intermittent wheezing and shortness of breath. The symptoms are associated with the worker's exposure to cedar dust, acrylic, and solvent-based glues. Pulmonary function studies for the patient and an account of his progress are included. The students read the description and answer a set of questions pertaining to the case. Students are encouraged to work in teams.


Patient 2 is a 37 year old tile setter who developed intermittent wheezing and shortness of breath.

Patient 2 experienced the onset of his asthmatic symptoms two years ago with shortness of breath, wheezing, and cough. The first episode occurred when he was carrying tiles upstairs. Over the last year he has required increasing bronchodilator medication to maintain his functional state and has noticed the shortness of breath becoming steadier and persisting into the night.

His shortness of breath tends now to be worse in the evening and early morning and often awakens him from sleep. He notes that he is irritated by dusts, particularly those resulting from carpentry work and drywall installation while he is laying tiles. His condition is greatly exacerbated by cold weather. Half-face mask cartridge respirators appear to help but are difficult to wear for long periods in his work.

He is presently taking Ventolin aerosol 2 puffs four times a day, Ventolin tablets 1 po four times daily (although he states that he often skips one), and Theodur capsules 300 mg/po twice daily but had accelerated to three times daily over the week just prior to his visit on December 13th. He has no know allergies. He has not smoked since 1976 when he quit his ten to fifteen cigarette per day habit. He relates that his breathing is better off of work and on holiday, becoming abruptly worse over a period of several hours and gradually worse over several days once he returns to work.

Immediately following his first clinic visit, he had a major decompensation. While working on a restaurant interior in which cedar was being cut on 21 January he noticed a drastic increase in his shortness of breath and the need for increased bronchodilator therapy. His breathing situation deteriorated and he presented to the Emergency Room on the evening of 23 January where he was given the diagnosis of bronchitis and was treated with an antibiotic which by history sounds like ampicillin. He had marked improvement and was feeling much better although he had not returned to work when he kept his appointment with me on 28 January. At that time there was no wheezing and he appeared to be much improved. He has been seen once since then on April 4. At this later visit he stated that his condition had remained fairly stable over the last several weeks and that he was still very much affected.

Patient 2 is self employed and both supervises part-time employees and performs his own installation work. He has found that his work habits can profoundly affect his bronchospasm in that the longer he stays at the job site, whether supervising employees or doing the work himself, the worse his reaction but if he limits his presence to only a couple of hours at a time he can avoid the most severe attacks. The agents in the workplace which appear to be most reliably associated with his bronchospasm episodes are cedar dust, acrylic, and solvent based glues. Latex (water-based) glues do not seem to trigger his response although they have a strong and annoying odor. Exposure to dust of any type, whether sawdust, drywall, dust, or cut tile dust appears to increase his bronchospasm response but do not appear to trigger asthmatic attacks and did not seem to be specific in their response. The exception to this generalization is cedar dust which does seem to provoke a specific response.

Table 1. Pulmonary function studies obtained on
20 December for Patient # 2

AGE: 37 HT: 174 cm WT: 72.0 kg

NONSMOKER

Results: Before Results: After
Bronchodilator Bronchodilator

TLC(Box) 8.13 L 130% Pred 7.94 L 127% Pred
TLC(He) 7.24 L 115% Pred
VC 5.01 L 108% Pred 5.39 L 1 1 6 %
Pred
FVC 4.50 L 4.85 L
FRC(Box) 5.01 L 191% Pred 4.77 L 182% Pred
RV(Box) 3.13 L 210% Pred 2.55 L 171 % Pred
VOL Trapped air .89 L

RAW 1.03 cm H20/Usec
.85 cm H20/Usec
SGAW >0.13 .19 (cm H20*sec)~' .25 (cm H20*sec)~'

FIF 5.47 USEC 84% Pred
FEV1 2.83 L 73% Pred 3.42 L 89% Pred
FEV1 57% VC 65% VC
FEV1 63% FVC 71%
FVC
ET-FEV1 > 75% .61 L 32% ERV 1.01 L 46% ERV
FEF (25-75) 1.53 USEC 33% (Pred) 1.86 L/SEC 40% Pred
FLOWNOL LOOP V50 2.10 USEC 47% Pred 2.40 USEC 49% Pred
FLOWNOL LOOP V75 .75 USEC 33% Pred .75 USEC 31 % Pred
MW **** UMIN **% Pred
ALV C02 3542 MMHG

REPORT: There is moderate and at least partially reversible airway obstruction. RV is slightly increased. VC is normal. The results are similar to those seen in patients with asthma or a mixture of asthma and bronchitis.

It was our impression that Patient #2 is suffering from a characteristic presentation of occupational asthma and would be classified as a late responder. That is, his primary response to inhaled agents is displaced by several hours and appears in the evenings instead of during the day. Dr. Margaret Turner-Warwick has observed the same phenomenon of sleep disturbance in her series of cases as that presented by this patient.

Two issues remain to be clarified, however. The first is the contribution of nonallergic, irritant exposures to his airflow obstruction and the second is the degree of variability in his peak flow during the day. These are important to the management of his condition because the identification of a certain process or antigen which precipitates his bronchospasm could lead to the elimination of the agent from his working environment. If there is a nonspecific contribution from irritant agents, that option is not so important.

In order to fully characterize the temporal sequence of Patient 2's response, we provided him with a portable spirometer and instructions on how to complete a diary recording his daily activities and flow measurements. This approach has been used with a considerable success by the occupational pulmonary group at the Brompton Hospital. Working backwards from the onset of the late response, we would then identify a period of time or process associated with the onset of the response with a view toward identifying a specific exposure. Although the device we had available to lend recorded both FVC and FEV, a peak flow meter works as well and is more generally available.

On 28 January, we issued the portable spirometer to Patient #2 with instructions to complete a log of his activities and readings taken on the spirometer. He was instructed to record the date, time, present location, the location one half hour before the log entry, current activity, presence or absence of shortness of breath, the spirometer reading for FVC and for FEV1. Each was recorded every two hours. The data were then plotted and the trends examined for an association between the decline in pulmonary function and his work day (Figure 1). In making this evaluation, it is important to realize that his work activity 4 to 6 hours beforehand is as important in the evaluation as his present work at the time of the pulmonary function reading. A careful analysis of this record shows that the patient has a pronounced diurnal variation in his pulmonary function normally but there is a clearly discernible pattern of reduced pulmonary function occurring several hours after work followed in most instances by a recovery usually most pronounced on the second day after removal from work. When the diurnal variation is present on days that he is away from work, it is usually less pronounced and falls to a minimum value less than those that can be observed in the diurnal variation on his work days. These findings are compatible with those detected by the Brompton group among patients with documented occupational asthma.

We considered the possibility of performing bronchoprovocation studies to determine precisely the agents which were most potent in triggering an asthmatic response in this case. We decided against such an evaluation because the time necessary to perform it would be grossly excessive and because the consistency of decline in pulmonary function in almost every work day and the patients history of sensitivity to several agents makes it extremely unlikely that any specific exposure would be found that the patient could avoid and still retain his current occupation. A thorough bronchoprovocation trial would require approximately two weeks of testing conducted almost every day and in this case the benefit would be nowhere near worth the cost. Furthermore, the substances to which he is sensitive by history seem to be unavoidable in his occupation so that the utility of identifying a specific agent in his case is questionable.

Unfortunately, the implications for the patient are quite unfavorable. He is experiencing permanent partial disability from occupational asthma and continued exposure to workplace antigens and irritants is likely to increase the severity and resistance to treatment of his asthma.

Economic conditions are forcing a choice this patient in that he must now rethink his business situation. Hiring employees to do the hands-on work would result in considerable reduction in his income, given the need to match the competition on bidding for jobs in the current economic climate. His employees are now hired on a piecework basis and have a high turnover, with resulting expense and need for supervision.

He filed a claim with the Workers' Compensation Board of Alberta, which was accepted. He is considered to be completely and permanently disabled for his usual occupation. It was suggested that he investigate the possibility of moving into an area of the interior construction business that would not involve exposure to glues or grouts and would involve a minimum exposure to dust. Possibilities include the wholesale or retail sale of specialty tiles or similar products. At this point, the patient's future employment prospects cease to become a medical problem and become one of economics. Should he find it necessary to enter an entirely different line of work, retraining assistance may be available through WCB.

__________
Included here is a figure plotting FEV, and FVC during working days; patient #2
______________

Prepared by Dr. Tee L. Guidotti
10 August 1992




Name: ____________________

l.D. No.: ___________________
Case Study #2

Maximum time required: 30 Minutes Please turn in only the blue sheet. Credit given for completion of exercise. You are welcome to work in teams.

1.a. What do you think is the principal hazard in this situation?

b. How would you confirm your impression?

2.a. What do you think is the principal health outcome of concern in this situation?

b. How would you confirm your impression?

3.a. How can this situation be corrected and further problems prevented in the future?

b. What is the physicians role in prevention in this situation?

4. Are the workers with health complaints fit to return to work in their usual occupation without presenting an excessive risk to themselves or others?

___Fit
___Unfit
___Fit with restriction: __________

5. On a scale of 1-10 where 10 is highest, how interesting did you personally find this material?





This document was last modified on 06/14/2000 03:07:50 PM



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