Panic disorder in emergency department chest pain patients: prevalence, comorbidity, suicidal ideation, and physician recognition

Rush immunotherapy (RIT) with house dust extract was given to 15 patients with mild extrinsic or mixed asthma. Every patient was strongly positive for IgE on the radioimmunosorbent test and sensitive to house dust extract on the scratch skin test. Nine patients were positive on the bronchial provocation test to house dust extract and 6 could not be examined. All patients did not drop out and got to house dust extract solution 10(-1) within 1 week. The symptom-medication scores decreased significantly after RIT. During RIT 1 patient developed a mild asthmatic attack and 3 patients developed generalized skin reaction. Eight weeks later, the threshold for house dust-provoked bronchoconstriction increased in 9 patients, but did not in 3 patients. The blood eosinophil count and blood histamine level significantly decreased. We conclude that RIT is able to raise antigen concentrations for a short periods and effective but not risky for mild asthma.     

Localized periorbital edema as a clinical manifestation of sulfite sensitivity

Sulfite is commonly used in pharmaceuticals as a preservative. We report a unique clinical presentation of localized periorbital edema on the left eye after administration of sulfite-containing dexamethasone. The patient's sulfite sensitivity was confirmed by sulfite oral provocation test: periorbital edema on the same site developed after ingestion of 200 mg sodium bisulfite. She was non-atopic and did not complain of any respiratory symptoms. Allergy skin prick test with 100 mg/ml sodium bisulfite showed a negative result. She also has aspirin-sensitive urticaria which was confirmed by oral provocation test. In conclusion, sulfite can induce a localized periorbital edema, an uncommon manifestation in sensitive patients. Further investigations are needed to clarify the pathogenetic mechanisms.     

Increase in non-specific bronchial hyperresponsiveness without specific response to isocyanate in isocyanate-induced asthma: a pilot study

Increased non-specific bronchial hyperresponsiveness (BHR) has been reported after positive reaction to isocyanates in patients with isocyanate-sensitive asthma. The increased responsiveness may, however, also precede the asthma attack. We therefore compared non-specific BHR to a cholinergic agent before and after exposure to toluene-diisocyanate (TDI) that induced no asthma symptoms in 11 workers with isocyanate-related asthma. Patients were exposed for 3 consecutive days to progressively increasing doses of TDI (5, 10, and 20 ppb min-1 for 20 min) in an exposure chamber with continuous TDI monitoring. No immediate nor late asthmatic bronchial reaction was observed in any patient after any dose of TDI during or after challenge. A significant increase in non-specific BHR was noted 24 h after the last dose of TDI challenge, however. This increase was at least one doubling dose for seven of 11 patients. In conclusion, our study shows that, in patients with isocyanate-induced asthma, exposure to TDI induces a slight but significant increase in non-specific BHR in the absence of any immediate or late bronchial response to isocyanate. This result, which requires further confirmation, may justify a proposal to measure non-specific BHR, even after a negative specific inhalation test to TDI, as an additional diagnostic element for TDI-induced occupational asthma, to help lower the percentage of the undetected occupational asthma cases.     

Specific bronchial provocation tests with flour in the diagnosis of occupational bronchial asthma

The gold standard in the diagnosis of occupational asthma is the specific bronchial provocation test (sBPT), but other diagnostic criteria have been proven to have a similar sensitivity, mainly in asthma due to high molecular weight compounds. In order to assess wether some clinical findings can predict the positive response to sBPT, we studied 37 subjects (14 millers and 23 bakers) with suspected occupational asthma who underwent sBPT with wheat flour dust (dust exposure in a small cabin: geometric mean 12.1 mg/m3 for up to 30 min). A positive response to sBPT (FEV1 > 20%) was elicited in 20 subjects (11 early, 4 late, and 5 dual responses). There was no significant difference between subjects with positive or negative sBPT as regards mean age, smoking, length of employment, duration of symptoms, atopy (skin positivity to one or more common allergens) and PD20FEV1 methacholine. The percentage of subjects with work-related symptoms was significantly higher in subjects with positive sBPT with respect to subjects with negative sBPT (81% versus 41.2%, p < 0.01 by chi 2 test); furthermore, FEV1 was significantly lower in subjects with positive sBPT. The percentage of positive skin response to wheat flour extract (mean wheal diameter > or = 3 mm) was mildly but not significantly higher in subjects with positive sBPT (68.4% versus 41.2%). None of the following clinical factors (age < 35 years, asthma symptoms pre-existing occupational exposure, non smokers, atopy and bronchial hyperresponsiveness to methacholine), alone or in combination, were associated with higher prevalence of positive sBPT. We conclude that the response to sBPT in subjects with suspected occupational asthma due to flour dust can not be adequately predicted by other clinical, allergologic and functional data. Therefore, sBPT with flour dust should always be performed in subjects with suspected occupational asthma.     

Frequency and correlative relation of diagnostic criteria in animal dander allergy

355 out-patients with signs of bronchial asthma were studied with special reference to animal dander sensitization. Case histories allowed the clinical diagnosis of an allergy to animal dander in 75 patients (21.1%). Skin testing is a useful means, as large reactions appear in most cases of animal dander allergy (60.7% are greater than or equal to + + + -reactions). Skin reactions, however, often are "false positive" or "false negative". Therefore, bronchial provocation tests are necessary if the case history is doubtful and/or the skin reaction is less than a + + + -reaction. There is a positive correlation between skin reaction and bronchial provocation test. No negative inhalation tests were seen when the skin reaction was greater than + + +. However, a positive inhalation test can be correlated with a negative or weakly positive skin test. The probability of common structural properties of different mammalian dander allergens is discussed. Avoidance of exposure to the animal is recommended as the therapy of choice.     

Establishment of a series of alien monosomic addition lines of Japanese bunching onion (Allium fistulosum L.) with extra chromosomes from shallot (A. cepa L. aggregatum group)

We performed an oral tolerance test for potassium metabisulfite in 33 patients and discovered sulfite intolerance in 9. These 9 patients had rhinitis including 7 with asthma. Alcoholic beverages, especially champagne, were the triggering factors the most frequently found for respiratory manifestations. Alcoholic beverages triggered bronchial or nasal reactions in 7 patients out of 9 (rhinitis in 7, asthma in 2). As in a large number of published cases, sulfite intolerance was evidenced by respiratory manifestations in our patients. Exceptional anaphylactic reactions have also been reported. Respiratory intolerance to sulfites in uncommon. A nasal or bronchial reaction occurring within minutes following ingestion of alcoholic beverages is highly suggestive of sulfite intolerance as is the development of acute asthma after administration of sulfite-containing drugs. Diagnosis is confirmed by oral tolerance tests versus placebo. The only effective preventive measure is to eliminate food and drugs containing sulfites. Such measures are justified to prevent acute episodes of asthma.     

Evaluation of the Brusini glaucoma staging system for follow-up in glaucoma

There is evidence that bronchial responsiveness to allergen is quantitatively correlated with bronchial responsiveness to nonspecific stimuli in subjects with allergic asthma. This association has been questioned in occupational asthma due to low molecular weight substances. It was the aim of this study to assess the quantitative association of bronchial responsiveness to methacholine (MCH) and platinum salts (Pt), in the form of hexachloroplatinic acid, in workers with occupational asthma due to Pt salts. Fifty-seven subjects with exposure to Pt, work-related asthma, and a positive bronchial challenge with Pt underwent skin prick test with Pt and bronchial challenge with MCH. Using the provocation concentration causing a > or = 50% fall in specific airway conductance (PC50sGaw(Pt)) as a dependent variable, anamnestic data (period from first symptoms to removal, period between removal from exposure and diagnosis, and smoking), season of the investigation, skin prick tests with environmental allergens, total immunoglobulin E (IgE), skin reactivity to Pt (Pt concentration causing a 2 mm wheal), and PC50sGaw(MCH) were included as independent variables for regression analysis. Fifty-two subjects (91%) showed a PC50sGaw(MCH) < 8 mg.mL-1 (geometric mean for all subjects 1.6 mg.mL-1). Responsiveness to Pt varied widely between subjects (geometric mean of PC50sGaw(Pt) 9 x 10(-5) mol.L-1, range 2 x 10(-7) to 10(-2) mol.L-1). There was no univariate correlation between bronchial responsiveness to MCH and Pt, but there was a correlation between skin reactivity to Pt and PC50sGaw(Pt) (r = 0.6). This association could not be improved by considering PC50sGaw(MCH), the period from first symptoms to removal, or the period between removal from exposure and diagnosis. The parameters that showed the highest (negative) associations with PC50sGaw(Pt) were skin reactivity to Pt and the period between removal from exposure and diagnosis (r = 0.65). We conclude that there is a moderate association between bronchial responsiveness to platinum salts and skin reactivity to platinum salts. However, there is no association between methacholine responsiveness and bronchial responsiveness to allergen in occupational asthma due to platinum salts.     

The nerves of two''s, three''s and four''s: a simple method for learning the neuroanatomy of the forearm

Mukali (Aningeria robusta) is an exotic wood from the Sapotaceae family. We describe the case of a 31-year-old woman who developed bronchial asthma and contact urticaria after occupational exposure to mukali. A positive immediate response was observed in the skin prick test, bronchial challenge and the rubbing test performed with a mukali wood extract. We suggest that an IgE-mediated immunological mechanism could explain these findings. Our case report identifies another wood dust capable of inducing occupational asthma.     

Testing bronchial hyper-responsiveness: provocation or peak expiratory flow variability?

BACKGROUND: Assessing bronchial hyper-responsiveness (BHR) is a main diagnostic criterion of asthma. Provocation testing is not readily available in general practice, but peak expiratory flow (PEF) is. Several guidelines promote the use of PEF variability as a diagnostic tool for BHR. This study tested the agreement between histamine challenge testing and PEF variability, and the consequences for diagnosing asthma. AIM: To investigate the possibility of assessing BHR by PEF variability, using a histamine provocation test as a reference. METHOD: Subjects with signs of symptoms indicating asthma (persistent or recurrent respiratory symptoms or signs of reversible bronchial obstruction) (n = 323) were studied. They had been identified in a population screening for asthma. A histamine provocation test and PEF variability were assessed over a three-week period. Asthma was defined as signs or symptoms together with a reversible airflow obstruction or BHR to the histamine challenge test. BHR was defined as a PC20 histamine of < or = 8 mg/ml or a PEF variability of > or = 15%. Overall correlation between PC20 and PEF variability was calculated using Spearman's rho. Furthermore, a decision tree was constructed to clarify the role of BHR in diagnosing asthma. RESULTS: Thirty-two patients had a reversibility in forced expiratory volume in 1 second (FEV1) of > or = 9% predicted, 131 patients showed a PC20 of < or = 8 and 11 patients had a PEF variability of > or = 15%. Overall correlation was poor at only -0.27 (P < 0.0001). One hundred and fourteen of the 131 patients diagnosed as having asthma when the histamine challenge test was used were not diagnosed by PEF variability. CONCLUSION: PEF variability cannot replace bronchial provocation testing in assessing BHR. This indicates that PEF variability and bronchial provocation do not measure the same aspects of BHR. If BHR testing is required in diagnosing asthma, a bronchial provocation test has to be used in general practice as well.     

Occupational allergy in greenhouse workers: sensitization to Tetranychus urticae

BACKGROUND: Tetranychus urticae (TU) is a macroscopic mite which is found infesting a large number of plants of economic interest. It has rarely been described as a cause of occupational allergic disease in agricultural workers. OBJECTIVE: To describe TU sensitization in greenhouse workers attending the outpatient allergy unit and its clinical associations, and to characterize the allergens involved. MATERIALS AND METHODS: Twenty-four consecutive carnation greenhouse workers with allergy-related symptoms, referred to our outpatient clinic during a 6-month period, were included. We made the diagnostic extract from carnation leaves heavily infested with TU. Skin-prick test, specific IgE measurement and bronchial provocation test with TU extract were carried out in all subjects. Allergen characterization was achieved by SDS-PAGE (sodium dodecylsulfate-polyacrylamide gel electrophoresis) and immunoblotting. RESULTS: Sixteen patients (66%) presented positive skin-prick test and specific IgE and were diagnosed allergic to TU. Fifteen patients suffered from bronchial asthma, 14 rhinitis and five urticaria. Twelve exhibited positive bronchial provocation test to the TU extract. On RAST-inhibition studies, there was no evidence of crossreactivity between TU extract and D. pteronyssinus. An allergen at 19 kDa was determined in the TU extract by SDS-PAGE immunoblotting studies. CONCLUSION: TU could be an important occupational allergen in greenhouse workers showing allergic symptomatology. There is no crossreactivity between this mite and the house dust mite D. pteronyssinus.     

Scorpion stings in Spain. Popular therapies, proverbs and pharmacopoeias]

There is evidence that bronchial responsiveness to allergen is quantitatively correlated with bronchial responsiveness to nonspecific stimuli in subjects with allergic asthma. This association has been questioned in occupational asthma due to low molecular weight substances. It was the aim of this study to assess the quantitative association of bronchial responsiveness to methacholine (MCh) and platinum salts (Pt), in the form of hexachloroplatinic acid, in workers with occupational asthma due to platinum salts. Fifty seven subjects with exposure to Pt, work-related asthma, and a positive bronchial challenge with Pt, underwent skin prick tests with Pt and bronchial challenge with MCh. Using the provocation concentration causing a > or = 50% fall in specific airway conductance (PC50sGaw(Pt)) as dependent variable, anamnestic data (period from first symptoms to removal, period between removal from exposure and diagnosis, and smoking), season of the investigation, skin prick tests with environmental allergens, total immunoglobulin E (IgE), skin reactivity to Pt (Pt concentration causing a 2 mm wheal), and PC50sGaw(MCh) were included as independent variables for regression analysis. Fifty two subjects (91%) showed a PC50sGaw(MCh) < 8 mg.mL-1 (geometric mean for all subjects 1.6 mg.mL-1). Responsiveness to Pt varied widely between subjects (geometric mean of PC50sGaw 9 x 10-5 mol.L-1, range 2 x 10-7 to 10-2 mol.L-1). There was no univariate correlation between bronchial responsiveness to MCh and Pt, but there was a correlation between skin reactivity to Pt and PC50sGaw(Pt) (r = 0.6). This association could not be improved by considering PC50sGaw(MCh), the period from first symptoms to removal, or the period between removal from exposure and diagnosis. The parameters that showed the highest (negative) associations with PC50sGaw(Pt) were skin reactivity to Pt and the period between removal from exposure and diagnosis (r = 0.65). We conclude that there is a moderate association between bronchial responsiveness to platinum salts and skin reactivity to platinum salts. However, there is no association between methacholine responsiveness and bronchial responsiveness to allergen in occupational asthma due to platinum salts.     

Plasma histamine changes during provoked bronchospasm in asthmatic patients

Seven patients with bronchial asthma underwent bronchial inhalation challenge with aerosolized allergen extracts and methacholine. Simultaneously, venous blood samples were collected and histamine was measured. Each patient was challenged on successive days with an allergen extract to which he had no skin-sensitizing antibody (skin test-negative allergen), followed by methacholine and skin test-positive allergen. Bronchospasm was not induced by inhalation of skin test-negative allergens but was observed in all patients after methacholine and in the majority of patients after skin test-positive allergens. No changes in plasma histamine were detected after challenges with methacholine and skin test-negative allergens. After challenge with skin test-positive allergens, significant rises in plasma histamine were detected in 5 of 7 patients. Plasma histamine was elevated within the first 5 min after inhalation of aerosolized allergen, and elevations persisted as long as 30 min. These studies showing that histamine increases significantly in the plasma during allergen-induced asthma in man suggest that histamine should be considered as at least one of the mediators of bronchospasm in allergic asthma. Bronchospasm induced by the cholinergic drug methacholine, unlike allergen-induced bronchospasm, is not associated with changes in plasma histamine.     

The effect of inhaling a dry powder of sodium chloride on the airways of asthmatic subjects

Wet aerosols of 4.5% sodium chloride (NaCl) are often used to assess the bronchial responsiveness associated with asthma. We questioned whether dry NaCl could be used as an alternative. Dry powder NaCl was inhaled from capsules containing either 5, 10, 20 or 40 mg to a cumulative dose of 635 mg. The powder was delivered via an Inhalator or Halermatic. The airway sensitivity to the dry and wet NaCl was compared in 24 patients with asthma aged 19-39 yrs. All subjects responded to both preparations and the geometric mean (95% confidence intervals) for the provocative dose of NaCl causing forced expiratory volume in one second (FEV1) to fall 20% from baseline (PD[20,NaCl]) for dry NaCl was 103 mg (68-157) versus 172 mg (102-292), p<0.03 for the wet NaCl. The response to dry NaCl was reproducible and on repeat challenge the PD20 was 108 mg (75-153). The mean maximum fall in FEV1 was approximately 25% on each of the two test days. Spontaneous recovery occurred within 60 min after challenge with dry NaCl and within 5 min after bronchodilator. There were no serious side-effects requiring medical attention, however some patients coughed on inhalation of the 40 mg dose and three gagged. Arterial oxygen saturation remained within normal limits. We conclude that a suitably prepared dry powder of sodium chloride could potentially replace wet sodium chloride to assess bronchial responsiveness in patients with asthma, but further studies are required to establish the long-term stability of the dry powder preparation.     

Neurotrophins are increased in bronchoalveolar lavage fluid after segmental allergen provocation

The mechanisms linking inflammation and airway hyperresponsiveness in allergic bronchial asthma are still not completely defined. Since neurotrophic factors increase nerve excitability and neurotransmitter synthesis and are produced by immunocompetent cells, they are likely candidates as mediators of inflammation and hyperresponsiveness. We tested the hypothesis that neurotrophin concentrations will increase in the bronchoalveolar lavage (BAL) fluid from patients with asthma after segmental allergen provocation. For this purpose an individually standardized dose of allergen or saline was instilled into different segments during bronchoscopy in eight subjects with mild allergic bronchial asthma. Segments were then lavaged 10 min and 18 h after allergen challenge or saline instillation. There was a significant increase in the neurotrophins nerve growth factor, brain-derived neurotrophic factor, and neurotrophin-3 in BAL fluids 18 h after allergen but not saline challenge. We conclude that neurotrophins are produced endobronchially following allergen provocation, suggesting a contribution to the pathogenesis of asthma.     

Correlation between antigen-specific IL-2 response test and provocation test for egg allergy in atopic dermatitis

BACKGROUND: The antigen-specific interleukin-2 response (AIR) test using lymphocytes is effective in searching for the antigen which causes allergic diseases and understanding their disease activity. OBJECTIVE AND METHODS: The correlation between the raw egg oral provocation test and egg white antigen-specific interleukin-2 (IL-2) response test was investigated in 123 children with infantile atopic dermatitis and 13 children with bronchial asthma. RESULTS: Among the 83 who showed positive reactions to provocation, 75 also reacted positively to the AIR test (sensitivity, 90.4%), while among the 53 children who showed negative responses to antigen provocation, 45 produced negative responses to the AIR test (specificity, 84.9%). The specificity of egg white IgE RAST score and skin-prick test are 88.7 and 81.3% which are comparable to that of the AIR test. However, their sensitivity was low (38.6 and 66.7%). In the patterns of symptom developed in the provocation AIR displayed late and delayed type allergic responses in addition to the immediate type which RAST reflected. The RAST-negative group composed of 98 patients included 51 (52.0%) who exhibited positive reactions to the provocation test. Among these 44 responded positively to the AIR test (86.3%). CONCLUSION: The AIR test is effective for screening egg white antigen as part of the tests for antigens responsible for allergic diseases and as a test to ascertain the relevant antigens, and that the conditions that could not be diagnosed by RAST can be detected by the AIR test.     

Evaluation of the hormonal status of patients with bronchial asthma by using various drug doses

Drug loads were used to diagnose impairments of the hypothalamic-pituitary-adrenal system in 209 patients with bronchial asthma. A thyroid-releasing hormone test made in patients with moderate bronchial asthma who were taking no corticosteroids (CS) demonstrated a high level of thyroid-stimulating hormone at min 60 of the agent administration, which was indicative of decreased hypothalamic function. In 67.8% of patients, the vasopressin test was positive and suggested that the pituitary preserved its functional capacities. The decreased secretion of hydrocortisone and its active forms was observed in patients with severe bronchial asthma when CS was used in the daily dose adequate to 10-15 mg of prednisolone for 5 years. The 20-day therapy with dexamethasone demonstrated that the agent reduced the synthesis of hydrocortisone to a greater extent than that of corticosterone. The administration of depot-synacthen 24 hours later elevated the content of all hydrocortisone fractions and biologically active corticosterone. Depot-synacthen exerted an active stimulating action on the adrenal cortex.     

Longitudinal study of bronchial hyperreactivity using the carbachol test with school children

STUDY DESIGN: Bronchial hyperresponsiveness of 476 schoolchildren (10.8 +/- 2.3 years) was studied three times at 12 months' intervals. The cumulative dose of 400 micrograms carbachol was applied in 50 + 50 + 100 + 200 micrograms steps. A fall of FEV1 of at least 15% was regarded as positive reaction. The test was save, as no severe obstruction was observed, only three children withdrew because of unpleasant cough. RESULTS: Reactivity was observed in 19.1, 10.0, and 5.2% of children at the occasion of the first, second and third test (sensitivity/specificity for prevalence of physician diagnosed asthma: 70/83, 35/91, and 24/96%, respectively). Reactivity was age dependent (7-11 years: 35%, 12-16 years: 18%), not influenced by sex, and the relative risk to be reactive was 1.9 in children 2-3 weeks after a respiratory tract infection. CONCLUSION: For epidemiological purposes carbachol provocation test--like other unspecific bronchial provocation tests--is inappropriate as a single test to classify individuals as asthmatics.     

Nedocromil sodium in treatment of bronchial asthma

Clinical study on efficiency of the nedocromil sodium (Tilade, Fisons) was performed in 20 patients with atopic and nonatopic bronchial asthma. The drug was administrated in dose of 8 mg per day for 2 months which allowed to renounce regular using of Beclocort forte after 7 days of the treatment. In both types of bronchial asthma the positive effect of nedocromil sodium was confirmed, causing increase of pulmonary ventilation and decrease of bronchial hyperactivity. Especially profitably effect was noticed in atopic bronchial asthma in which statistically important increase of peak expiratory flow (PEF) was obtained and decrease of bronchial hyperreactivity by PC20 for histamine was observed (p < 0.05). Mentioned above spirometric parameters did not differ in statistically important pattern in patients with nonatopic bronchial asthma, when Beclocort forte group with Tilade group compared. Neither important differences in general number of cells nor percentage composition of cell smears were observed in bronchoalveolar lavage fluid.     

Comparison of bronchial challenge with ultrasonic nebulized distilled water and hypertonic saline in children with mild-to-moderate asthma

There is still controversy about the most suitable method to measure bronchial hyperresponsiveness in children. In epidemiological surveys, nonisotonic aerosols are being used increasingly for bronchial provocation testing. Our aim was to study the acceptability, safety and correlation between two published bronchial challenge tests. Two standardized protocols--the inhalation of hypertonic saline (HS) and ultrasonically-nebulized distilled water (UNDW)--were performed in 36 children: 19 patients with the clinical diagnosis of mild-to-moderate asthma (7-12 yrs of age), and 17 control subjects (8-18 yrs of age). HS challenge involved stepwise inhalation of 4.5% saline (for 0.5, 1, 2, 4 and 8 min), whereas challenge with UNDW was performed as a single step protocol with 10 min inhalation of cold UNDW. Asthma medication was withheld prior to challenge testing. Thirty five subjects completed both challenge tests (one asthmatic patient did not return after UNDW challenge) in random order within a 7 day time interval. For HS a > or = 15% reduction in forced expiratory volume in one second (FEV1) from baseline was considered a positive response, and for UNDW a > or = 10% decrease. In 13 of the 19 asthmatic patients, but in none of the controls, a positive response was observed for UNDW. Fifteen out of 18 patients and one control subject had a positive response to HS. Twelve out of 18 asthmatic children responded to both challenges, three responded only to HS and three had no response to either challenge. There was a negative correlation between log provocative dose causing a 15% reduction in FEV1 (PD15) after HS and the maximum fall in FEV1 after UNDW (rs = -0.63; p < 0.005). The HS challenge had a lower acceptability than challenge with UNDW due to the unpleasant salty taste of HS. However, this did not inhibit the completion of the tests in any subject. The results of this study suggest a good correlation between response to hypertonic saline and ultrasonically-nebulized distilled water in children with mild-to-moderate asthma. A multiple step protocol might be safer when applied in field studies involving children.     

Fate of occupational asthma. A follow-up study of patients with occupational asthma due to Western Red Cedar (Thuja plicata)

Thirty-eight patients with red cedar asthma proved by inhalation provocation test were studied after they had left exposure for more than 6 months. Twenty-seven patients became asymptomatic, with normal lung function (group A). Three patients had persistent chronic bronchitis with a moderate degree of airway obstruction, probably as a result of cigarette smoking (group B1). Eight patients continued to have recurrent attacks of asthma that decreased in severity after cessation of exposure, and their symptoms were probably due to previous exposure (group B2). The effect of breathing helium on maximal expiratory flow at 50 per cent of the vital capacity was studied. All except one patient in group A were responders (change in maximal expiratory flow at 50 per cent of vital capacity greater than 30 per cent). Two patients in group B1 and 2 in group B2 were nonresponders, suggesting obstruction in the small airways. All patients with red cedar asthma demonstrated bronchial hyperreactivity to methacholine to the same extent as patients with nonoccupational asthma. This hyperreactivity persisted after they left exposure, irrespective of symptoms. It is not known at present whether bronchial hyperreactivity is the predisposing factor in occupational asthma or is the result of the disease.