Biomedical subjects

H Ghezzo

Publications and source records attributed to H Ghezzo.

At least 91 records · Page 5Linked to original sources

PubMed1989

Duration of action of inhaled terbutaline at two different doses and of albuterol in protecting against bronchoconstriction induced by hyperventilation of dry cold air in asthmatic subjects.

Although several studies have examined the duration of the bronchodilator effect of several inhaled beta-2-adrenergic agents, the duration of the blocking effect on bronchial hyperresponsiveness, another key feature of asthma, has seldom been studied. We investigated this problem in eight adult asthmatic subjects who underwent hyperventilation tests with dry cold air on 4 different days. On the first day, five hyperventilation tests with assessment of the level of ventilation causing a 20% fall in FEV1 (PD20) were obtained to evaluate the within-day variability of the test. On the three other visits, after a baseline hyperventilation test, albuterol 200 micrograms, terbutaline 500 micrograms, and terbutaline 1,500 micrograms were administered in a double-blind, randomized way. Hyperventilation tests were carried out 1, 2, 4, and 6 h later. The blocking effect on the treatment days, as assessed by the differences in PD20 for each test compared with baseline PD20 for that day, was corrected for the within-day variability of the control day. There was a significant bronchodilator effect 1 h after administering the drug; it was equivalent for albuterol 200 micrograms (25.6 +/- 14.7%) and terbutaline 1,500 micrograms (21.7 +/- 13.5%) and significantly less for terbutaline 500 micrograms (14.1 +/- 10.0%). Complete or partial blockade on bronchial responsiveness was obtained in the majority (six to seven of eight) of the subjects 1 h after inhaling the bronchodilator, with progressive reduction in the effect later on. Four subjects still showed a blocking effect 6 h after terbutaline 1,500 micrograms was administered, one subject after terbutaline 500 micrograms, and no subjects after albuterol (chi square = 6.6, p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗

PubMed1989

Bronchial hyperresponsiveness to inhaled methacholine in subjects with chronic left heart failure at a time of exacerbation and after increasing diuretic therapy.

Cough and wheezing are common findings in left heart failure. However, it is still questionable whether nonallergic bronchial hyperresponsiveness, the hallmark of asthma, is also associated with this condition. In 12 subjects with acute decompensation of chronic postischemic LV failure, we assessed the PC20 methacholine during an episode of acute LV failure and after five to 15 days of intensive diuretic therapy. Weight, arterial blood gases, plethysmographic lung volumes, and expiratory flows were also measured on both visits. Extravascular lung water was estimated indirectly with a radiologic score. During acute decompensation, six subjects had significant airway obstruction and eight had a PC20 less than or equal to 16 mg/ml (significant bronchial hyperresponsiveness). After diuretic therapy, subjects improved significantly, losing an average of 2.2 kg, but they still had chronic LV failure and evidence of an obstructive breathing defect. Although mean PC20 was unchanged, three subjects had significantly improved PC20 after treatment. We conclude that: (1) left ventricular failure is often associated with mild bronchial hyperresponsiveness, although it is not excluded that smoking and the resulting possibility of bronchial obstruction can also play some role; and (2) acute treatment does not generally alter bronchial responsiveness to methacholine, suggesting that chronic LV failure can cause chronic changes to the airways.

Aged↗

PubMed1989

Occupational asthma due to various agents. Absence of clinical and functional improvement at an interval of four or more years after cessation of exposure.

We have previously shown that in some subjects with occupational asthma caused by various agents, there is no improvement approximately two years after exposure ended. These results could be explained by the short interval between diagnosis and follow-up. In the current study, we saw 28 subjects with occupational asthma at two intervals, 2.3 years (range, three months to 5.7 years) and 5.8 years (range, 4.3 to 10.9 years) after the cessation of exposure. Various causes of occupational asthma were included. The diagnosis was confirmed in 26 of the cases by specific inhalation challenges in the laboratory, and in the remaining two cases by combined monitoring of peak expiratory flow rates and bronchial responsiveness. All subjects had symptoms of asthma at both follow-up assessments. There were no changes in the need for medication, spirometry, or bronchial hyperresponsiveness. Depending on the interval of the follow-up, four to six subjects required inhaled steroid agents in addition to the usual bronchodilators, 11 had FEV1 less than 80 percent of predicted, and 26 or 27 had an abnormal PC 20 histamine. Only two subjects demonstrated sustained improvement in PC 20 at the first and second follow-ups, and one other showed changes during the second follow-up assessment which were not present at the first. We conclude that except for three subjects, the need for medication did not diminish, nor did airway obstruction and hyperresponsiveness improve in this group of subjects with occupational asthma long after exposure ended. These results differ from other studies, which demonstrated that some recovery takes place in a greater proportion of individuals.

Asthma↗

PubMed1989

Influence of the duration of inhalation of cold dry air on the resulting bronchoconstriction in asthmatic subjects.

Hyperventilation of cold dry air causes bronchoconstriction in asthmatic subjects and has been proposed as a test for assessing bronchial hyperresponsiveness. The influence of the duration of inhalation of unconditioned cold air has not been studied. We have investigated the question in 12 asthmatic subjects in a clinically stable state. Each subject underwent three inhalation tests at a maximum interval of two weeks. On each day, the duration of inhalation was different, being randomly 2, 3 or 4 min depending on the subject. Doubling doses of cold air produced by a freon conditioner were administered, increasing ventilation from 7.5 to 15, 30, 60 l.min-1 and maximum voluntary ventilation (MVV). Forced expiratory volume in one second (FEV1) was assessed after each period of cold air inhalation. The test was stopped when the FEV1 had decreased by 20% or more, or when MVV had been achieved. The dose of cold air expressed as the level of ventilation causing a 20% change in FEV1 (PD20) was interpolated from individual dose-response curves. Dose-response curves shifted to the left when the duration of ventilation was increased. PD20 was significantly lower after 3 min of ventilation than after 2 min (mean +/- SD PD20 of 41.7 +/- 1.4 l.min-1 compared with 53.3 +/- 1.2 l.min-1; p = 0.002). There was a further fall in PD20 after 4 min of ventilation (PD20 = 36.1 +/- 1.5 l.min-1) but the difference compared with the values obtained after 3 min was not significant (p = 0.09), thus suggesting a plateau.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Nonspecific bronchial hyperresponsiveness to inhaled histamine and hyperventilation of cold dry air in subjects with respiratory symptoms of uncertain etiology.

Fifty adult subjects referred to a respiratory function laboratory of a tertiary care hospital for respiratory symptoms of uncertain etiology were investigated prospectively by means of a questionnaire, isocapnic inhalation of dry cold air (-20 degrees C), histamine inhalation tests, monitoring of peak expiratory flow rates, total eosinophil counts, and total IgE. Wheezing, tightness in the chest, dyspnea, and cough were reported by 35, 23, 41, and 30 subjects, respectively. FEV1 values less than 80% pred were found in only 2 subjects. Twenty-nine subjects had a PC20 histamine less than or equal to 16 mg/ml. Twenty, 15, and 10% falls in FEV1 were found in 10, 18, and 26 subjects, respectively, using hyperventilation of cold air. Significant eosinophilia and increased total IgE levels were seen in 5 and 18 subjects, respectively. Eight subjects had daily changes in PEFR greater than 20% on at least 1 day of monitoring. There was no significant association between specific responses to the respiratory questionnaire or the presence of rhinitis on the one hand and bronchial responsiveness to histamine and cold air on the other hand. The 10 subjects who demonstrated a greater than 20% change in FEV1 after cold air inhalation also had a PC20 less than 16 mg/ml, and 5 of them reacted at a concentration less than or equal to 2 mg/ml. Two subjects who had a PC20 less than or equal to 2 mg/ml demonstrated a less than 20% change in FEV1 after inhaling cold air. There was no association between the increase in total eosinophils or IgE and bronchial hyperresponsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Theophylline minimally inhibits bronchoconstriction induced by dry cold air inhalation in asthmatic subjects.

The aim of this study was to evaluate the effect of a sustained-release theophylline preparation on bronchial responsiveness to cold dry air inhalation in asthmatic subjects. Sixteen adult subjects with asthma in a clinical steady state underwent 3 isocapnic cold air challenges on 3 consecutive days at a time when they had not received oral theophylline medication over the past 3 days. The dose of cold air causing a 20% (PD20) fall in FEV1 was obtained from each subject's dose-response curve. Subjects were then administered active or placebo sustained-release theophylline preparations according to a double-blind, randomized, two-treatment crossover design. Medication was given for a minimum of 3 consecutive days. PD20 was reassessed on 4 different days, 3 to 4 h after receiving active or placebo medication (two visits for each medication). We found a significant bronchodilator effect of theophylline as compared to the placebo (mean +/- SD differences in changes of FEV1 of 8.8 +/- 1.9%). We also documented a significant blocking effect of the active medication as opposed to the placebo on PD20 (p = 0.01). This difference (mean = 0.18 on the loge scale) was statistically beyond the intraindividual between-day variability observed on the 3 control days (p less than 0.001) but was physiologically minimal. This blocking effect was also partially related to changes in airway caliber. We conclude that theophylline showed a blocking effect on bronchial responsiveness to dry cold air, which was physiologically minimal and was partially related to changes in airway caliber.

Adolescent↗

PubMed1988

Patterns of improvement in spirometry, bronchial hyperresponsiveness, and specific IgE antibody levels after cessation of exposure in occupational asthma caused by snow-crab processing.

Thirty-one workers with occupational asthma caused by snow-crab processing were assessed by a long-term follow-up on three occasions at mean +/- SD intervals of 12.8 +/- 5.4, 31.4 +/- 6.3, and 64.4 +/- 6.3 months after leaving work. The diagnosis of work-related asthma was initially confirmed in all of them by specific inhalation challenges at the workplace or by laboratory inhalation of snow-crab boiling water (n = 24) or by serial monitoring of airway caliber and bronchial responsiveness to histamine at work and off work (n = 7). Total duration of work-related exposure was 12.8 +/- 5.6 months (range, 3 to 21 months), and the duration of symptoms after onset was 6.8 +/- 4.2 months (range, 1 to 18 months). At the time of diagnosis, all 31 subjects required medication for asthma, 11 had a FEV1 less than or equal to 85% predicted, and all subjects had a PC20 less than or equal to 16 mg/ml. Twelve of 25 serum samples assessed showed high levels of specific immunoglobulin E (IgE) antibodies to crab meat and/or boiling water. At the time of the first follow-up, there was a reduction in the number of subjects still requiring medication, with a significant reduction in FEV1, and a PC20 less than or equal to 16 mg/ml. However, no further change was observed afterwards. Similarly, the mean FEV1 and FEV1/FVC improved significantly from the time of diagnosis to the first follow-up (p less than 0.01), with a plateau thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Acute exposure to sawdust does not alter airway calibre and responsiveness to histamine in asthmatic subjects.

We investigated the effects of particles of sawdust delivered through a special device at known concentrations (close to the threshold limit value-short term exposure limit (TLV-STEL) of 10 mg.m-3) on FEV1 and PC20 in 12 asthmatic subjects free of clinical sensitization to this product. Subjects were studied over two days (day 1: exposure to sawdust; day 2: sham exposure) in random order with a maximum interval of 1 week. On each day, after the assessment of spirometry and PC20, subjects underwent exposure to sawdust or sham exposure. Sawdust was inhaled for a total of 30 min at average concentrations varying from 8.0 to 19.3 mg.m-3 (mean = 11.5 mg.m-3). Twenty-five to 39.7% (mean = 34.6%) of inhaled particles had a diameter less than 10 mu (diameter allowing deposition in the trachea and lower respiratory tract). At the end of each period of exposure, FEV1 was assessed. After recovery, the second PC20 was obtained. Serial measurements of FEV1 were carried out every hour for up to 6 h after the end of exposure. At that time, PC20 was reassessed. Only one subject showed an acute bronchoconstriction immediately after exposure to sawdust (maximum fall of 14% in FEV1) with complete recovery 10 min later. Overall, inhalation of sawdust did not modify PC20 by comparing the mean result of the first test with the second and the third assessments. Also, the mean changes in PC20 at each interval after exposure to sawdust were not significantly different from the variations in PC20 on the sham day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Bronchoconstriction due to exercise combined with cold air inhalation does not generally influence bronchial responsiveness to inhaled histamine in asthmatic subjects.

We investigated immediate and late changes in airway responsiveness to histamine, after bronchoconstriction due to exercise combined with inhalation of cold air, in ten asthmatic subjects who came on six days. On the first visit, the provocation concentration producing 20% fall in FEV1 (PC20) histamine was obtained. After functional recovery, each subject walked on a treadmill whilst breathing dry, cold air. This resulted in an immediate fall greater than 15% (mean +/- SD = 31.9 +/- 11.0%) in forced expiratory volume in one second (FEV1). Following recovery, PC20 was measured again. FEV1 was then monitored for up to 6-8 h. PC20 was measured then and on the two following days at the same time of the day. Subjects were studied on three control days using the same design except that a resting period replaced the exercise with cold air. The mean changes in PC20 at each interval after exercise combined with cold air were not statistically significant. Physiologically significant changes were obtained in only two subjects, reaching a maximum 8 h after the manoeuvre. In these subjects, changes in PC20 were reproducible during a second series of visits. It is concluded that bronchial responsiveness to histamine is not generally influenced by the bronchoconstriction due to exercise combined with cold air.

Adolescent↗

PubMed1988

Kinetics of the recovery from bronchial obstruction due to hyperventilation of cold air in asthmatic subjects.

The timecourse of recovery from bronchial obstruction due to inhaled cold air was studied in eight adult asthmatic subjects. On the first visit, bronchial responsiveness to inhaled histamine was assessed. On the other two visits, after assessment of baseline lung resistance (RL) and spirometry, dry cold (-20 degrees C) air was inhaled for three minutes. RL was monitored continuously until its return to baseline +/- 20%. The baseline concentration of histamine causing a 20% fall in FEV1 (PC20) varied from 0.03 to 5.9 mg.ml-1. The mean maximum increase in RL was 2-fold (2.03 +/- 0.41) and was reached 2-11 min after the challenge. RL values were linearly correlated to time (r2 values greater than 0.80 in 14/16 instances). The two slopes of recovery were not significantly different. Slopes of recovery and total time of recovery (14-55 min) varied greatly between subjects. No relationship was found between baseline airway calibre, bronchial hyperresponsiveness and maximal increase in baseline RL on the one hand and the slopes of recovery on the other.

Adult↗

PubMed1987

Shape of the dose-response curve to cold air inhalation in normal and asthmatic subjects.

Inhalation of cold air at increasing levels of minute ventilation with assessment of bronchomotor tone between each inhalation (dose-response curve) has been used as a method to assess bronchial hyperresponsiveness. However, no information is available on the shape of the obtained dose-response curve, and it is not known if a plateau of response is reached. We investigated this problem in 13 adult asthmatic subjects (PC20 methacholine results varying from 0.04 to 15.2 mg/ml), 5 normal and 2 former asthmatic individuals (PC20 greater than 8 mg/ml). Inhalation dose-response curves were drawn by asking the subjects to inhale dry cold air (-20 degrees C) for 3 min at progressively increasing degrees of ventilation (5, 10, 15, 20, etc., L/min) until maximal voluntary ventilation (MVV) or sufficient bronchoconstriction was reached. FEV1 was assessed after each degree until no further decline was seen. No functional recovery was observed before asking the subject to inhale the next dose of cold air. Maximal falls in FEV1 ranged from 20.7 to 56.5% in the current asthmatic subjects, whereas no significant (less than 10%) changes in FEV1 were obtained in the normal and former asthmatic individuals. Seven to 13 points on the individual dose-response curves were obtained for each current asthmatic subject. Curves were analyzed using the common pharmacologic logistic model. The coefficients of correlation were, in general, highly statistically significant. Curves obtained for the current asthmatic subjects represented a truncated sigmoidal pattern without a plateau. Curves were flat in the normal and former asthmatic individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Occupational asthma and IgE sensitization in a pharmaceutical company processing psyllium.

We assessed the prevalence of occupational asthma and IgE sensitization to psyllium in a pharmaceutical company producing psyllium hydrophilic mucilloid, which is used as a laxative. Workers were intermittently exposed, approximately 5 times/yr, for periods of less than 10 days. Of the 140 employees, 130 (93%) were studied before a processing period via a questionnaire spirometry (n = 125), blood sampling (n = 118), and skin prick tests (n = 120) with 7 common inhaled allergens as well as plantain and psyllium. Thirty-nine workers had a history suggestive of occupational asthma. Twenty-three of 120 (19%) showed a skin wheal diameter greater than or equal to 3 mm to psyllium and 31 of 118 (26%) had increased specific IgE antibodies; 39 (32%) workers had at least 1 of these 2 features. Subjects with a questionnaire suggestive of asthma or occupational asthma were further investigated by serial monitoring of peak expiratory flow rates and PC20 methacholine before and during the psyllium processing period. All workers had spirometry repeated during the processing period. Twenty-one subjects who had a PC20 less than or equal to 16 mg/ml (n = 10) and/or decreased their PC20 by a greater than or equal to 3.2-fold difference (n = 4) and/or changed their FEV1 by greater than or equal to 10% (n = 13) during the processing period were referred for inhalation challenges to psyllium in the laboratory. Five of the 18 workers for whom these tests were feasible gave an immediate bronchoconstrictive reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Within- and between-day reproducibility of isocapnic cold air challenges in subjects with asthma.

Eight adult subjects with asthma had isocapnic cold air challenges on 4 different days. Three consecutive tests were performed on each visit with functional recovery between tests. Subjects were asked to breathe dry cold air (-20 degrees C) for progressively increasing levels of minute ventilation (7.5, 15, 30, and 60 L/min and maximal voluntary ventilation) until a 20% fall in FEV1 had been reached or when maximal voluntary ventilation was done. FEV1 was assessed between each level. The doses of respiratory heat exchange and minute ventilation causing 10%, 15%, and 20% changes in FEV1 were interpolated from dose-response curves. The within- and between-day 95% confidence intervals based on a single determination on the loge scale varied from +/- 0.32 to 0.59 for the indices derived from respiratory heat exchange. Reproducibility of the between-day results was more satisfactory than for the corresponding within-day assessments. No significant within-day tachyphylaxis was demonstrated for these indices.

Adolescent↗

PubMed1986

Lack of acute effects of ascorbic acid on spirometry and airway responsiveness to histamine in subjects with asthma.

Sixteen adult subjects with asthma in a clinical steady state were studied. On day 1, after baseline spirometry, they underwent four histamine inhalation tests with functional recovery between each test. The provocative concentration causing a 20% fall in FEV1 (PC20) was obtained after each test. On days 2, 3, and 4, after baseline spirometry, active and placebo ascorbic acid (2 gm) was administered orally, double-blind, according to a 4.3.1 two-treatment crossover study design. One hour later, spirometry was performed, and PC20 was reassessed. We found no significant changes in FEV1 and FVC after ascorbic acid as compared with placebo administration. There was no difference between PC20 on days 2, 3, and 4 and by standardizing for the four PC20 results obtained on day 1. We conclude that ascorbic acid has no acute bronchodilator effect and does not alter bronchial responsiveness to histamine in subjects with asthma.

Adult↗

PubMed1986

Theophylline partially inhibits bronchoconstriction caused by inhaled histamine in subjects with asthma.

Sixteen adult subjects in a clinical steady state had four consecutive histamine inhalation tests on the same day when they were not receiving oral theophylline medication. The provocative concentration of histamine causing a 20% fall in FEV1 (PC20) was used to assess the response. They were then administered active or placebo sustained-release theophylline preparations according to a double-blind, randomized 4.4.1. two-treatment crossover design. Medication was administered for a minimum of 3 consecutive days, and PC20 was reassessed on 4 different days, 3 to 4 hours after receiving active or placebo medication (two visits for each medication). A significant but small bronchodilator and blocking effect on histamine excitability was demonstrated for the active medication. This latter effect was present even by adjusting for changes in baseline airway caliber and for the intraindividual variability of the four PC20 values obtained on day 1. We conclude that theophylline partially blocks bronchial responsiveness to inhaled histamine.

Adult↗

PubMed1986

IgE sensitization in snow crab-processing workers.

Occupational asthma is a highly prevalent disease among snow crab-processing workers, but its immunologic mechanism has not been identified. Prick skin tests with snow crab-meat extract, commercial extracts from other crab genera, and snow crab cooking water collected in 1984 were performed on 119 workers. Crab-specific IgE was assessed by RAST in sera from 115 workers with meat and water extracts. Both skin and RAST tests were performed in 58 individuals. Diagnosis of occupational asthma had previously been confirmed in 54 individuals. A highly significant relationship was demonstrated between the presence of immediate skin reactivity or increased serum levels of specific IgE to crab extracts and the occurrence of occupational asthma. There was good agreement between the results of skin and RAST tests with extracts of either meat or snow crab cooking water. Cooking water and snow crab-meat extracts were more sensitive than commercial preparations. Water extract was more potent and more sensitive than meat extract. We conclude that there is evidence that occupational asthma in snow crab-processing workers is mediated through an IgE mechanism.

Aerosols↗

PubMed1986

Alveolar fenestrae in smokers. Relationship with light microscopic and functional abnormalities.

We studied 12 smokers' lungs with scanning electron microscopy in order to analyze the distribution and size of alveolar fenestrae and their relationship to the average distance between alveolar walls (Lm) and lung function. Alveolar fenestrae in areas near terminal airways (respiratory bronchioles and alveolar ducts) were consistently larger than fenestrae far from airways (alveoli). Fenestrae in near areas increased in size as Lm increased (r = 0.845, p less than 0.001), whereas no correlation between Lm and fenestrae size in far areas was found (r = 0.281, NS). The overall area of fenestrae (near and far) correlated significantly with FEV1 (r = -0.745, p less than 0.01), MMEF (r = -0.752, p less than 0.01), and PL90 (r = -0.804, p less than 0.05). However, when subdivided into near and far, only fenestrae near the small airways showed a significant correlation with function. These findings suggest that in smokers with mild to moderate emphysema, destruction affects preferentially the areas around the terminal airways (near areas), and these changes, although small, might play an important role in the lung function.

Aged↗

PubMed1986

Cold air inhalation has a cumulative bronchospastic effect when inhaled in consecutive doses for progressively increasing degrees of ventilation.

In 12 asthmatic subjects, we compared the bronchoconstriction obtained with 3 methods of isocapnic inhalation of cold dry air (IICDA) on 6 visits, two visits for each method: Dose-response curves (DRC), which were obtained by asking the subjects to inhale at progressively increasing degrees of ventilation (7.5, 15, 30, 60 L/min and maximal voluntary ventilation [MVV] at a fixed breathing rate); free MVV, i.e., breathing frequency not set; same degree of ventilation as the last required for DRC (VEeq). Degrees of ventilation were significantly greater with the free MVV method. The percentage fall in FEV1 obtained by VEeq method was significantly lower than the changes recorded with the DRC and the MVV methods, the 2 latter being not significantly different. We conclude that IICDA induces a cumulative bronchoconstriction by the DRC method. However, the bronchoconstriction obtained with the latter method is not significantly different from the one obtained with the free MVV method.

Asthma↗