Update in allergy and immunology.

Internal medicine has witnessed astounding developments in our understanding of the immune system's role in the pathophysiology of many diseases. The present challenge is to harness this knowledge to develop more effective therapies for immune-related illness. Guidelines for the care of common illnesses such as asthma may encourage appropriate clinical application of advances in our armamentarium against immune disease.

Dyspnea and the larynx.

The larynx is an extremely important and complex part of our airway, and patients commonly seen by an allergist may have a large number of laryngeal problems that may be either totally or partially responsible for their presenting complaints. These problems may be structural in nature or may be related to abnormal motion of the vocal cords. A thorough knowledge of laryngeal anatomy, physiology, and possible pathology, combined with visualization of the larynx is necessary for accurate diagnosis.

A model for faculty practice teaching clinics developed at the Oregon Health Sciences University.

In 1988 the Oregon Health Sciences University established its first faculty practice teaching clinic wherein physicians in training were incorporated into a faculty private practice clinic; this pilot project proved very successful and has been subsequently adopted as the model for essentially all outpatient clinics (both medical and surgery) in the university system. The model encourages efficiency, overhead control, and appropriate staffing; it also compensates faculty members for their additional time spent teaching. The authors conclude this model may help other academic training centers adapt to the changing demands of medical education.

Exposure to an aeroallergen as a possible precipitating factor in respiratory arrest in young patients with asthma.

BACKGROUND: Exposure to airborne spores of the common mold Alternaria alternata has been implicated in asthma attacks. Such exposure is particularly frequent in the Midwest during the summer and fall months. To determine the role of A. alternata in triggering severe asthma attacks, we investigated the cases of 11 patients with asthma who had sudden respiratory arrest and determined the frequency of sensitivity to this allergen in these patients. METHODS: The 11 patients (age range, 11 to 25 years) with initial episodes of respiratory arrest, which was fatal in 2 patients, were identified in the course of their care in our pediatric and adult clinical allergy practice and by a retrospective review of all Mayo Clinic records of patients with severe asthma cared for between 1980 and 1989. Skin-test reactivity to A. alternata and levels of IgE antibody against this mold in the 11 patients were compared with those in 99 matched controls with asthma who had no history of respiratory arrest. RESULTS: All the patients came from the upper Midwest, and the episodes of respiratory arrest occurred in the summer or early fall. Ten of the 11 patients with asthma who had respiratory arrest (91 percent) had positive skin-puncture tests for sensitivity to alternaria, as compared with 31 percent of the controls (P less than 0.001), and the serum levels of IgE antibodies to alternaria were elevated in all 9 patients tested. Among the covariates we examined (age, sex, and distance from the Mayo Clinic), only age was a significant confounder. After adjustment for age, alternaria skin-test reactivity was found to be associated with an increase of approximately 200-fold in the risk of respiratory arrest (adjusted odds ratio, 189.5; 95 percent confidence interval, 6.5 to 5535.8). CONCLUSIONS: Exposure to the aeroallergen A. alternata is a risk factor for respiratory arrest in children and young adults with asthma.

Masqueraders in clinical allergy: laryngeal dysfunction causing dyspnea.

The allergist may be called upon to evaluate patients with dyspnea that is labeled "refractory asthma." In some patients, the site of origin of their dyspnea is the larynx. The diagnosis of laryngeal disorders requires a thorough understanding of the normal function of the laryngeal anatomy and physiology. Some patients with asthma may have a component of their airway obstruction in the larynx and large airways. Paradoxical vocal cord motion occurs when the true vocal cords approximate during inspiration, and although severe subjective dyspnea may occur, in most cases there is no evidence of hypoxia, hemoglobin desaturation, or an abnormality of the arterial-alveolar oxygen gradient. Provocative tests with methacholine are negative in this group of patients. Patients with PVCM are usually female and may have an affiliation with the medical profession. Many have psychologic difficulties, and the foundation of treatment is speech therapy and psychotherapy if indicated. Other disorders that may produce dyspnea from laryngeal dysfunction include Meige syndrome, abductor spastic dysphonia, and laryngospasm. Recognition of these disorders will expedite timely, accurate diagnosis and treatment.

Role of ventilation, air filtration, and allergen production rate in determining concentrations of rat allergens in the air of animal quarters.

Concentration of any substance in the air of a room is determined by the ratio between the rates of its production and removal. Thus, high concentrations can result from high production, low removal, or a combination of the two. Air filtration can supplement ventilation in removing allergens from the air. Control of aeroallergen exposure at any particular location would be more rational and effective if the contribution of production, ventilation, and filtration were known. Using immunochemical assays for rat urinary protein allergen, we measured the rate of production by individual rats and the concentration of allergens in the air of rat animal quarters where the ventilation rate was about 15 changes per hour. We introduced two different high-efficiency filtration systems that provided additional clean air changes up to a maximum of 127 changes per hour. Male rats shed about 20 ng/min of allergen. Because of this high rate of production, substantial reduction in rooms that housed large numbers of animals required the very high air-exchange rates that were achieved with laminar flow small animal isolator racks. Measured concentrations agreed well with concentrations calculated from a mass balance equation whose terms included numbers of animals in the room, production rate by individual animals, and rates of ventilation and filtration. We suggest that this principle of considering both production and removal rates applies not only to devising means of reducing levels of rat allergens in rat rooms, but generally to other indoor allergens as well.

Angiotensin converting enzyme inhibitors and the allergist.

Angiotensin converting enzyme inhibitors (ACEI) are used widely in the treatment of both hypertension and congestive heart failure. Although usually well tolerated, these medications may produce side effects that may be encountered by the allergist, including cough, angioedema, and rhinitis symptoms. The severity of ACEI-induced cough may vary, and is associated with increased bronchial hyperreactivity in some (but not all) patients as judged by methacholine sensitivity. Angiotensin converting enzyme inhibitor-induced cough may have its onset from one day to 12 months after initiation of therapy, and is not dose dependent. Angioedema caused by ACEI is usually mild and clears with discontinuation of the drug, however cases requiring intubation and tracheostomy have been reported. The mechanism of ACEI-induced cough remains unclear, but could be in part due to accumulation of substances whose degradation may also be impeded by ACEI, such as substance P, bradykinins, and/or prostaglandins. Knowledge of the side effects produced by this class of medication may help patients avoid unnecessary, costly, and often invasive diagnostic evaluations.

Building-related illness. A review of available scientific data.

The allergist-immunologist is ideally trained to play a critical role in the recognition and evaluation of patients with building-related illness. The practitioners of this subspecialty should also take an active role in critical studies that will expand the knowledge base in this whole area, and collaborate as well with colleagues in toxicology and industrial hygiene to develop accurate and sensitive measures of implicated pollutants, irritants, and allergens. The role of multiple low level pollutants on healthy workers must be assessed in an objective fashion. Methods to evaluate and enforce regulations on building ventilation should be developed and widely applied. It is only in this fashion that an expanding population of office workers can be assured a suitable work environment as we emerge from the age of the industrial blue collar worker to the technical, office-based white collar worker.