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Biomedical subjects

V Brusasco

Publications and source records attributed to V Brusasco.

At least 91 records · Page 5Linked to original sources
PubMed1990

Late asthmatic reaction to perennial and seasonal allergens.

Twelve patients with asthma sensitized to Dermatophagoides pteronyssinus and Parietaria judaica were studied. Patients were challenged before (winter), during (summer), and after (autumn) Parietaria-pollen season. Early asthmatic reaction was positive for both allergens, and the provocative dose causing a 15% decrease of FEV1 was similar in all seasons. The provocative dose of methacholine causing a 15% decrease of FEV1 and specific IgEs for both allergens were also not significantly different throughout the time of study. Late asthmatic reaction (LAR) to Dermatophagoides occurred in eight of 12 patients in winter, in six of nine in summer, and in five of six patients in autumn. The severity of LAR, expressed as the maximum fall of FEV1 3 to 8 hours after challenge, was not significantly different between seasons. LAR to Parietaria occurred in only one of 12 patients in winter, in six of 11 in summer, and in one of six patients in autumn. In summer, LAR to Parietaria was significantly more severe than in winter. In both winter and autumn, but not in summer, LAR to Dermatophagoides was significantly more severe than to Parietaria. We conclude that LAR is allergen specific, and natural exposure has a priming effect on LAR.

Adolescent↗
PubMed1990

Allergen-induced increase in airway responsiveness and inflammation in mild asthma.

The relationship between airway responsiveness to methacholine and inflammatory cells in bronchoalveolar lavage (BAL) was determined in patients with history of rhinitis and/or mild bronchial asthma either at baseline (10 patients) or 3-4 h after allergen inhalation challenge (11 patients). At baseline, airway responsiveness did not correlate with any BAL cell population. When data obtained after allergen challenge were included in the analysis, 44% of the variability of airway responsiveness was explained by a multiple regression model with BAL eosinophils as a directly correlated (P = 0.002) independent variable and with BAL macrophages as an inversely correlated (P = 0.045) independent variable. Changes in airway responsiveness after allergen challenge were predicted (82% of variance explained) by a model with BAL eosinophils and BAL lymphocytes as directly correlated (P = 0.0002 and P = 0.03, respectively) independent variables. We conclude that, in stable asymptomatic asthma, baseline airway responsiveness does not correlate with the presence in the airways of inflammatory and immunoeffector cells that can be recovered by BAL. Nevertheless the allergen-induced increase in airway responsiveness is associated with an influx of eosinophils and lymphocytes in the bronchial lumen.

Adult↗
PubMed1990

Effects of deep inhalation during early and late asthmatic reactions to allergen.

Eighteen asthmatic patients with a biphasic asthmatic reaction to house dust mite were studied. The effect of deep inhalation (DI) was quantitated by comparing the maximal expiratory flow at 40% (MEF40) of vital capacity from partial (P) and maximal (M) flow-volume curves, and specific airway conductance (SGaw) before and after DI (SGawDI). At baseline, the ratio MEF40M/P was significantly larger than unity (1.45 +/- 0.26 SD), whereas the ratio SGawDI/SGaw was not significantly different from unity (0.92 +/- 0.24). During early phase reaction, both MEF40M/P and SGawDI/SGaw were significantly increased to 2.66 +/- 0.97 and 1.96 +/- 0.47, respectively. During late phase reaction, when the FEV1 values were similar to those observed during early phase reaction, MEF40M/P and SGawDI/SGaw were 1.86 +/- 0.46 and 1.43 +/- 0.29, respectively, significantly higher than the values at baseline but significantly lower than those during early phase reaction. Similar results were obtained in a subgroup of nine patients when SGaw values during the late phase reaction were similar to those during the early phase reaction. We conclude that DI has a different effect during early and late asthmatic reactions, suggesting a different ratio of airway to parenchymal hysteresis. This may result from an increased parenchymal hysteresis (more peripherally located bronchial obstruction) or a decreased airway hysteresis (prominent airway inflammation) during the late phase reaction.

Adolescent↗
PubMed1989

[Evaluation of regional perfusion as an indicator of resectability in patients with centrally located bronchogenic carcinoma].

The value of using regional ventilation (V) and perfusion (Q) tests as signs of resectability has been analysed in 17 patients with centrally located lung cancers who underwent thoracotomy. The criteria for inclusion into the study were the following: (1) histological diagnosis of non-oat-cell carcinoma, (2) no distant metastases, (3) Q in the affected lung less than 40% and (4) evaluation by computed tomography of the extent of the tumor. Regional perfusion was investigated by intravenously injected 133 Xenon. CT scan proved to be the most sensitive test (90%) in order to identify non-resectable lesions; in 2 cases, however, the tumor was erroneously judged non-operable (specificity = 71%). For the evaluation of V and Q data, two parameters were assumed as a non-resectability index: (1) Q less than or equal to 30% and (2) V/Q greater than or equal to 1.5. Sensitivity was 80% for the former and 70% for the latter parameter, while specificity was 85% and 100% respectively. In conclusion, V and Q study may provide highly specific informations on the resectability of centrally located lung cancers, especially when assuming V/Q greater than or equal to 1.5 as discriminating value.

Carcinoma, Bronchogenic↗
PubMed1989

Effect of nedocromil sodium on the late asthmatic reaction to bronchial antigen challenge.

The effect of inhaled nedocromil sodium (4 mg by pressurized aerosol) on the dual asthmatic reaction to bronchial antigen challenge was studied in eight patients with asthma. The following prechallenge/postchallenge treatment combinations were administered: nedocromil sodium/placebo, nedocromil sodium/nedocromil sodium, placebo/nedocromil sodium, and placebo/placebo. Each patient received three treatment combinations assigned with a balanced incomplete block design. Nedocromil sodium administered before antigen challenge was significantly more effective than placebo in blocking both the early (p less than 0.001) and late (p less than 0.01) fall in FEV1. Postchallenge administration of nedocromil sodium tended to delay the onset of late asthmatic reaction but did not provide significant protection compared to placebo. These results demonstrated that nedocromil sodium prevents both phases of the dual asthmatic reaction to bronchial antigen provocation when it is inhaled before challenge. Further investigation is necessary to elicit a definite answer to whether nedocromil sodium administered after bronchial challenge has an effect on late asthmatic reaction.

Adolescent↗
PubMed1989

Pulmonary resistance during halothane anesthesia is not determined only by airway caliber.

Studies of the effect of halothane on airway smooth muscle have used pulmonary resistance as an index of airway caliber. However, pulmonary resistance (RL) is the sum of airway resistance (Raw), which changes with airway caliber, and of tissue resistance (Rti), which depends on the pressure-volume hysteresis of the lung. To separate the effects of halothane on airway caliber from its possible effects on tissue pressure-volume hysteresis in the unstimulated lung and during bronchoconstriction, the authors measured both components of RL before and during vagus nerve stimulation in 12 dogs before and during halothane administration. Rti was always the major component of RL, constituting 77 +/- 14% (mean +/- SD) of RL before vagus nerve stimulation and 64 +/- 21% of RL during stimulation in the absence of halothane. Vagus nerve stimulation caused approximately equal increases in both Rti and Raw. Halothane attenuated the response of both Rti and Raw to vagus nerve stimulation in a dose-dependent fashion. At 1 MAC, the Rti response was 44 +/- 13% of its value before halothane administration and the Raw response was 32 +/- 12% of its value before halothane administration; these responses were not significantly different. The authors conclude that changes in RL during halothane administration are caused not only by changes in airway caliber, as previously assumed, but also reflect a significant effect of halothane on lung tissue pressure-volume hysteresis.

Airway Resistance↗
PubMed1989

Partitioning of pulmonary resistance in dogs: effect of tidal volume and frequency.

To determine the sensitivity of pulmonary resistance (RL) to changes in breathing frequency and tidal volume, we measured RL in intact anesthetized dogs over a range of breathing frequencies and tidal volumes centering around those encountered during quiet breathing. To investigate mechanisms responsible for changes in RL, the relative contribution of airway resistance (Raw) and tissue resistance (Rti) to RL at similar breathing frequencies and tidal volumes was studied in six excised, exsanguinated canine left lungs. Lung volume was sinusoidally varied, with tidal volumes of 10, 20, and 40% of vital capacity. Pressures were measured at three alveolar sites (PA) with alveolar capsules and at the airway opening (Pao). Measurements were made during oscillation at five frequencies between 5 and 45 min-1 at each tidal volume. Resistances were calculated by assuming a linear equation of motion and submitting lung volume, flow, Pao, and PA to a multiple linear regression. RL decreased with increasing frequency and decreased with increasing tidal volume in both isolated and intact lungs. In isolated lungs, Rti decreased with increasing frequency but was independent of tidal volume. Raw was independent of frequency but decreased with tidal volume. The contribution of Rti to RL ranged from 93 +/- 4% (SD) with low frequency and large tidal volume to 41 +/- 24% at high frequency and small tidal volume. We conclude that the RL is highly dependent on breathing frequency and less dependent on tidal volume during conditions similar to quiet breathing and that these findings are explained by changes in the relative contributions of Raw and Rti to RL.

Airway Resistance↗
PubMed1989

Effect of beta-adrenergic blockade on response to exercise in sedentary and active subjects.

The response to incremental work after placebo and propranolol (80 mg, orally) was studied in 11 sedentary (S) and 11 physically active (PA) healthy subjects. O2 uptake, CO2 output, and minute ventilation were significantly reduced at all or most work rates after propranolol in S subjects, whereas in PA subjects only O2 uptake was occasionally significantly reduced. Maximum work capacity during the propranolol trial was significantly increased by 17% in the S group but was unaltered in the PA group. A subanaerobic threshold constant work test in five sedentary subjects demonstrated that propranolol had no effect on the respiratory response both early and late in exercise. In addition, propranolol did not impair the ability of the respiratory control system to maintain alveolar PCO2 at new set points when external dead space was added during constant load work. We conclude that alterations of gas exchange during incremental work after propranolol administration are related to both physical fitness and type of exercise.

Adult↗
PubMed1988

Gas exchange and intrapulmonary distribution of ventilation during continuous-flow ventilation.

In 12 anesthetized paralyzed dogs, pulmonary gas exchange and intrapulmonary inspired gas distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation [inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1] were evaluated. Intrapulmonary gas distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but the alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, gas distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.

Animals↗
PubMed1988

Lung function following upper sleeve lobectomy for bronchogenic carcinoma.

Eight patients who underwent upper sleeve lobectomy and six who underwent upper simple lobectomy for lung cancer were studied. The two groups were matched for age and preoperative lung function as assessed by standard spirometry. Post-operative lung function studies, including measurements of regional ventilation (Vr) and perfusion (Qr) by 133 Xenon technique showed that: 1) two weeks after surgery, forced expiratory volume at 1 s was more reduced after simple than after sleeve lobectomy, but in both groups Vr and its vertical gradient were similarly reduced in the operated lung compared to the contralateral; 2) one year after sleeve lobectomy, the vertical gradient of Vr tended to disappear in both lungs while Vr and Vr/Qr of the operated side increased significantly. These results indicate that early after surgery lung function may be less impaired after sleeve than simple lobectomy; however, long-term changes of regional lung function may occur after sleeve lobectomy resulting into a high Vr/Qr ratio in the operated lung.

Adult↗
PubMed1988

The fluoroallergosorbent test: a comparison with rast and skin test in respiratory allergy.

Specific IgE antibodies to common inhalant allergen were measured in ten healthy and 82 rhinitic or asthmatic subjects by both FAST and RAST. Significant correlations were found between FAST and RAST results for grass, Parietaria, Dermatophagoides, and cat dandruff. For these allergens the agreement between FAST and prick test was similar to that between RAST and prick test. In contrast to RAST and/or prick test, for Tag alder and birch allergens, the FAST apparently gave false negative results. In conclusion, FAST seems to be a promising technique for in vitro measurement of specific IgE against most inhalant allergens but some improvement is still necessary in standardizing allergens for this assay.

Adolescent↗
PubMed1987

Effect of nedocromil sodium on adenosine- and methacholine-induced bronchospasm in asthma.

The effect of nedocromil sodium on adenosine-induced bronchospasm was investigated in eight asthmatic patients. Nedocromil sodium (4 mg) administered by aerosol 10 min before challenge, effectively inhibited adenosine-induced bronchospasm. In another group of six asthmatic patients, nedocromil sodium administered in the same way did not reduce the bronchial response to methacholine. These results support the view that adenosine-induced bronchospasm may be prevented by a membrane stabilizing drug and is not mediated through cholinergic pathways. The mechanism(s) by which nedocromil sodium inhibits adenosine-induced bronchospasm requires further investigations.

Adenosine↗
PubMed1987

Bioavailability and pharmacokinetics of a new controlled-release theophylline preparation in the form of capsules containing pellets.

The bioavailability and pharmacokinetics of a new controlled-release theophylline preparation in the form of capsules containing pellets of coated drug were studied in 10 healthy subjects. Results showed that the bioavailability of this preparation is complete after oral intake of a single dose, while after repeated administrations (300 mg b.i.d.) theophylline serum levels are constantly within the therapeutic range (10-15 mg/l) with small fluctuations over 12 h. Side effects were not observed.

Administration, Oral↗
PubMed1986

Predictive accuracy of late asthmatic reaction to Dermatophagoides pteronyssinus.

Sixteen patients with asthma were challenged with solutions of Dermatophagoides pteronyssinus extracts. Fifteen patients demonstrated an early asthmatic reaction, and 10 patients also demonstrated a late asthmatic reaction, as demonstrated by a 15% decrease of FEV1 within 1 hour or between 3 and 8 hours after challenge, respectively. Airway responsiveness to inhaled methacholine, expressed as the dose causing a fall of FEV1 of 15% (Pd15), and the serum IgE level (RAST), expressed as percent of the total radioactivity added, were also measured. Multiple regression analysis of data demonstrated that both early asthmatic reaction, expressed as the allergen Pd15, and late asthmatic reaction, expressed as the FEV1 maximum fall from control values, can be predicted with similar accuracy (explained variance of 63% and 68%, respectively) by a model that incorporates simultaneously methacholine Pd15, percent of total radioactivity added by RAST, and baseline values of FEV1. We conclude that the late asthmatic reaction is more likely to occur and is more severe in patients with more severe underlying disease.

Adolescent↗
PubMed1986

Resonant amplification of delivered volume during high-frequency ventilation.

The volume of gas delivered from a high-frequency ventilation (HFV) circuit was measured with an ultrasonic flowmeter. The measurements were done in vitro (20-liter air-filled glass bottle) and in vivo (9 anesthetized dogs lying supine) at oscillation frequencies ranging from 4 to 23 Hz and stroke volumes of the pump ranging from 36 to 150 ml. We varied the length and diameter of the tube connecting the pump with the endotracheal tube, the length and diameter of the bias outflow tube, the diameter of the endotracheal tube, and the stroke volume of the pump. Both in vitro and in vivo, there was resonant amplification of the delivered gas volume; i.e., the delivered gas volume exceeded the stroke volume at certain frequencies. Altering the dimensions of connecting tube, endotracheal tube, bias outflow tube, or stroke volume, i.e., changing the resistance to gas flow, gas compliance, and/or gas inertance in these elements, altered the ratio of gas delivered to stroke volume that could be predicted by an electric analog. These data indicate that the delivered gas volume during HFV depends critically on the configuration of the HFV circuit, the size of the endotracheal tube, the oscillation frequency, and the pump stroke volume. Knowledge of the delivered gas volume during HFV and appreciation of the phenomenon of resonant amplification of the delivered gas volume will permit a more accurate description of factors contributing to gas transport during HFV.

Animals↗
PubMed1986

Exercise testing in radiologically-limited, simple pulmonary silicosis.

Forty-five consecutive patients (17 non-smokers and 28 smokers) affected by pulmonary silicosis with limited profusion of radiologic small opacities of "p" type underwent physical examination; resting standard pulmonary function tests (PFT); and progressive, multistage, treadmill-based exercise testing (ET). Results show that, in 78 percent of all patients, maximum oxygen uptake (VO2max) was below 80 percent of predicted, and in most cases this was accompanied by a reduction of anaerobic threshold and/or oxygen pulse. In our group, VO2max predicted was uncorrelated with PFT parameters, symptoms and x-ray picture. No significant differences in response to exercise were observed between smokers and non-smokers. Therefore, exercise was limited by factors other than ventilatory limitation. It is concluded that ET is not more sensitive than PFT for assessing ventilatory impairment in patients with early, simple silicosis, even though it may be valuable for providing information about other sources of exercise limitation.

Adult↗