Effects of cyclo-oxygenase inhibition on exhaled eicosanoids in patients with COPD

BACKGROUND

Leukotriene (LT) B4 concentrations are increased and prostaglandin (PG) E2 concentrations are decreased in exhaled breath condensate (EBC) in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to investigate the short term effects of cyclo-oxygenase (COX) inhibition on exhaled LTB4 and PGE2 concentrations in patients with COPD and to identify the COX isoform responsible for exhaled PGE2 production.

METHODS

Two studies were performed. A double blind, crossover, randomised, placebo controlled study with ibuprofen (400 mg qid for 2 days), a non-selective COX inhibitor, was undertaken in 14 patients with stable COPD, and an open label study with oral rofecoxib (25 mg once a day for 5 days), a selective COX-2 inhibitor, was undertaken in a different group of 16 COPD patients. EBC was collected before and after drug treatment. Exhaled LTB4 and PGE2 concentrations were measured with specific immunoassays.

RESULTS

All patients complied with treatment as indicated by a reduction in ex vivo serum thromboxane B2 concentrations (ibuprofen) and a reduction in lipopolysaccharide induced increase in ex vivo plasma PGE2 values (rofecoxib) of more than 80%. Exhaled LTB4 was increased after ibuprofen (median 175.5 (interquartile range 128.8-231.5) pg/ml v 84.0 (70.0-98.5) pg/ml, p < 0.001) and exhaled PGE2 was reduced (93.5 (84.0-105-5) pg/ml v 22.0 (15.0-25.5) pg/ml, p < 0.0001). Rofecoxib had no effect on exhaled LTB4 (p = 0.53) or PGE2 (p = 0.23).

CONCLUSIONS

Non-selective COX inhibition decreases PGE2 and increases LTB4 in EBC, whereas selective COX-2 inhibition has no effect on these eicosanoids. PGE2 in EBC is primarily derived from COX-1 activity, and COX inhibition may redirect arachidonic acid metabolism towards the 5-lipoxygenase pathway.

Validation of 8-isoprostane and prostaglandin E 2 measurements in exhaled breath condensate

OBJECTIVE

To qualitatively validate radioimmunoassays for 8-isoprostane and prostaglandin (PG) E(2) in exhaled breath condensate.

SUBJECTS

Twenty-two subjects with different lung diseases attended the outpatient clinic on one occasion for exhaled breath condensate collection.

METHODS

Samples were pooled together and purified by reverse phase high performance liquid chromatography (RP-HPLC). The eluted fractions were assayed for 8-isoprostane-like immunoreactivity and PGE(2)-like immunoreactivity by radioimmunoassays. In addition, simultaneous measurements of exhaled breath condensate unextracted samples with two anti-8-isoprostane and anti-PGE(2) sera with different cross-reactivity were performed.

RESULTS

A single peak of 8-isoprostane-like immunoreactivity and PGE(2)-like immunoreactivity co-eluting with 8-isoprostane (retention time: 13 min) and PGE(2) (retention time: 21 min) standards, respectively, was identified by radioimmunoassays. Testing with two different antisera showed similar results for both 8-isoprostane-like immunoreactivity (limits of agreement = 4.5 pg/ml and - 4.1 pg/ml, n = 12) and PGE(2)-like immunoreactivity (limits of agreement = 6.1 pg/ ml and - 6.1 pg/ml, n = 12).

CONCLUSION

This study provides evidence for the specificity of the radioimmunoassays for 8-isoprostane and PGE(2) in exhaled breath condensate. This is critical for proposing these markers as a non-invasive way for monitoring airway inflammation.

Validation of leukotriene B4 measurements in exhaled breath condensate

OBJECTIVE

To qualitatively validate an enzyme immunoassay to measure leukotriene B4 in exhaled breath condensate. Exhaled breath condensate is a new non-invasive method to monitor airway inflammation.

SUBJECTS

Twenty-two subjects with different lung diseases attended the outpatient clinic on one occasion for exhaled breath condensate collection.

METHODS

Samples were pooled together and purified by reverse-phase high-performance liquid chromatography. The fractions eluted were assayed for leukotriene B4 by enzyme immunoassay.

RESULTS

A single peak of leukotriene B4-like immunoreactivity co-eluting with leukotriene B4 standard (retention time: 24 min) was identified by enzyme immunoassay. Reverse phase-high performance liquid chromatography peak of leukotriene B4 was clearly separated from those of 6-trans-leukotriene B4 (retention time: 14 min) and leukotriene B5 (retention time: 18 min) for which the antiserum used in the enzyme immunoassay had the highest cross-reactivity. Leukotriene B4 recovery was 64%.

CONCLUSIONS

This study provides evidence for the presence of leukotriene B4 in the exhaled breath condensate and the specificity of the enzyme immunoassay used.

Correlates of osteoporosis in chronic obstructive pulmonary disease

The aim of this study was to analyse the correlates of reduced bone mineral density in patients with chronic obstructive pulmonary disease (COPD), with special regard to a possible protective role of hypercapnia. One hundred and four consecutive COPD inpatients in stabilized respiratory conditions underwent a comprehensive assessment of their health status. Bone mineral density was measured by X-ray absorptiometry at the lumbar site and at the femoral neck site. Differences in health-related variables between patients with (group O, n=62) and without (group N, n=42) lumbar and/or femoral neck osteoporosis were assessed first by univariate analysis and then by logistic regression analysis aimed to identify independent correlates of osteoporosis. Group O was characterized by worse nutritional status, as reflected by indices exploring either lean or fat mass, and by a trend towards lower forced expiratory volume in 1 sec/forced vital capacity ratio. Arterial tension of carbon dioxide lacked any correlation with bone mineral density. According to the logistic regression analysis, body mass index < or = 22 kg m(-2) qualified as the only and positive independent correlate of osteoporosis (odds ratio=4.18; 95% confidence intervals=1.19-14.71). In conclusion, malnutrition characterizes COPD patients with osteoporosis, while mild to moderate hypercapnia lacks either a positive or negative effect on bone mineral density. Longitudinal studies are needed to identify predictors rather than correlates of bone mineral density.

Slow compartment features and gas exchange impairment in mild asthma: effects of beta agonist inhalation

Static and dynamic lung volumes, arterial blood gases, alveolar ventilation and ventilation-perfusion (VA/Q) relationships were studied in 14 mild asthmatic patients and in 7 normal subjects (as controls) before and after fenoterol inhalation. Multiple nitrogen washout curves were analyzed by a bicompartmental distribution model, in order to assess the distribution of ventilation and VA/Q mismatch. At baseline, asthmatics showed mild airway obstruction and gas exchange impairment [forced expiratory volume in 1 s (FEV1) = 79% pred; PaO2 = 87.4; alveolar-arterial oxygen tension gradient (AaPO2) = 22.9 mm Hg]. By analysing nitrogen washout curves, an alveolar slow space representing 45.1% of total lung volume (vs. 36.8% in normals; p = 0.044) was identified; its alveolar ventilation per minute per unit lung volume (VA2/L2) was lower than in normals (p = 0.01). beta-Agonist inhalation by the asthmatics, which reversed airway obstruction (FEV1 = 98% pred.; p < 0.001) and improved gas exchange (PaO2 = 92.6 mm Hg, p < 0.001; AaPO2 = 16.8 mm Hg, p = 0.003), led to a highly significant increase in VA2/L2 (p = 0.001). The improvement in PaO2 was associated with the increase in VA2/L2 (r2 = 0.39; p = 0.017), but not with the increase in FEV1. Lastly, the changes in FEV1 and VA2/L2 were not correlated with each other. We conclude that even in mild stable asthma there is substantial unevenness of ventilation, detectable by bicompartmental analysis of nitrogen washout curves, which is responsible for gas exchange impairment and is not related to common spirometric parameters. In addition, the improvement in gas exchange is probably due to the effect of fenoterol on the tributary airways of the alveolar slow compartment. This effect can be assessed by this simple method, which can be used in clinical pharmacology studies and in the follow-up of asthmatic patients.

Respiratory function impairment in pulmonary tuberculosis

Main alterations of respiratory function in pulmonary tuberculosis are analyzed. Due to the wide range of clinical manifestations, all possible patterns of dysfunctions are described with particular reference to the impact on gas exchange. Possible sequelae of pulmonary tuberculosis are also reported.

Airway disease: anatomopathologic patterns and functional correlations

Airways represent a serial and parallel branched system, through which the alveoli are connected with the external air. They participate in the mechanical and immune defense against noxious agents, regional flow regulation to optimize the perfusion/ventilation ratio and provide lung mechanical support. Functional exploration of central airways is based on resistance measurement, flow-volume curve or spirometry, while peripheral airways influence parameters as the upstream resistance, the slope of phase III nitrogen washout and the residual volume. Bronchodynamic tests supply important information on airway reversibility and nonspecific reactivity. Anatomopathologic alterations of obstructive chronic bronchitis, pulmonary emphysema and bronchial asthma account for their specific functional and bronchodynamic alterations. There is a growing interest for bronchiolitis in the clinical, radiologic and functional field. This type of lesion, always present in COPD, asthma and interstitial disease, becomes relevant when isolated or predominant. The most useful anatomofunctional classification separates the "constrictive" forms, the cause of obstruction and hyperinflation, from "proliferative" forms where an intraluminal proliferation more or less extended to alveolar air spaces as in BOOP (bronchiolitis obliterans organizing pneumonia) results in restrictive dysfunction. Constrictive bronchiolitis obliterans represents a severe and frequent complication of lung and bone marrow transplantation. Idiopathic BOOP may occur with cough or flue-like symptoms. In other cases, constrictive and proliferative forms may have a toxic (gases or drugs), postinfective or immune etiology (rheumatoid arthritis, LES, etc). Respiratory bronchiolitis or smokers' bronchiolitis, an often asymptomatic lesion, rarely associated to an interstitial lung disease, should be considered separately. The relationships between respiratory bronchiolitis, COPD and initial centriacinar emphysema is still to be elucidated. The diagnostic combination of the more sensitive functional tests with HRCT will allow a better understanding of the natural history of the various forms of bronchiolitis.

Deaths from asthma in Italy (1974-1988): is there a relationship with changing pharmacological approaches?

In this article we consider the relationship between asthma mortality rates, obtained from the Italian National Institute of Statistics (ISTAT), and the doses of all antiasthmatic drugs except systemic steroids sold in Italy in the years 1974-1988. The total asthma mortality rate showed three different trends: it decreased slowly until 1978 (period A); increased 10-fold from 1979 to 1985, rising from 0.30 to 4.17/100,000 (period B); and remained stable until 1988 (period C). More than half of the deaths in 1988 occurred in people 75 years of age or more. Men died more in the older age groups, while the mortality of women prevailed in the 35- to 54-year age group. In the 5- to 34-year age group the rate rose from 0.01 in 1978 to 0.21 /100,000 in 1986. Coding changes due to the 9th revision of the International Classification of Disease, adopted in Italy in 1979, probably increased the number of deaths being attributed to asthma in case of contemporary mention of bronchitis, a common diagnosis in older men, which showed the greatest increase in mortality. Increased prevalence and awareness of asthma may also have played a role. Although international comparisons strongly suggest undertreatment of asthma in Italy, the doses of anti-asthma drugs sold in Italy grew from 276 to 1,080 million from 1974 to 1985. During period B xanthine sales rose sevenfold and grew from 6.5 to 23.3% of the total doses, along with a twofold increase in beta 2-agonist and cromolyn sales. Period C was characterized by stable total doses (1155 million in 1988), with increases only in antiinflammatory and preventive drug sales. The increase in asthma deaths in Italy has been striking despite the contemporary rise in sales of all antiasthma drugs, particularly of beta 2-agonist metered aerosols and xanthine tablets. The increase in antiinflammatory and preventive drug sales may have contributed to the stabilization of asthma deaths during period C.

Lung function in children and adolescents with occasional exposure to environmental tobacco smoke

We investigated the effects of occasional exposure to environmental tobacco smoke (ETS) on lung function in children. A total of 317 healthy 12- to 15-yr-old nonsmoking children and adolescents, living in households in which none of the adults were active smokers, were selected for the present analysis. The urinary cotinine:creatinine ratio (CCR) was taken as the biologic indicator of exposure, and children were classified according to CCR quartiles. The ratio between FEV1 and FVC (FEV1/FVC) and both early (peak expiratory flow [PEF]) and midexpiratory flow rates (FEF25-75) were lower in children with higher CCR values. In percent terms, the decrease in adjusted lung function for children belonging to the second, third, and fourth quartiles in comparison with those in the first quartile was -1.37, -2.12, and -1.94 for FEV1/FVC (p for trend = 0.012); 0.98, -3.31, and -4.54 for PEF (p for trend = 0.024); and -0.05, -4.85, and -6.13 for FEF25-75 (p for trend = 0.022), respectively. The effects remained significant when possible confounding by father's education and urinary creatinine level had been taken into account, and when children whose parents' smoking status may have been misclassified were excluded. This study suggests an adverse effect on lung function from even low-level exposure to ETS among nonsmoking children living with reportedly nonsmoking parents.

Predicting mortality of patients hospitalized for acutely exacerbated chronic obstructive pulmonary disease

PURPOSE

To identify factors affecting the short-term prognosis of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD).

PATIENTS AND METHODS

The 590 patients having COPD as primary disease who were hospitalized in the pneumology unit of a university hospital from 1981 to 1990 were studied. A standardized protocol for the treatment of acutely exacerbated COPD was adopted for all the patients. The patient records were retrospectively analyzed by two observers, and 23 clinical and laboratory variables defining the patient status on admission were collected. Age and arterial gas data were also taken into account, and the outcome mortality was recorded. Interobserver reproducibility was tested by computing the kappa coefficient and Spearman's rho for dichotomous and continuous variables, respectively. The relationship of clinical and laboratory factors to the outcome was assessed first by univariate analysis and then by a logistic regression analysis assessing the independent predictive role of variables previously shown to be univariately correlated with mortality.

RESULTS

The mortality rate was 14.4%. The logistic regression analysis identified four independent predictors of death: age (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.04 to 1.11), alveolar-arterial oxygen gradient greater than 41 mm Hg (OR 2.33; 95% CI 1.39 to 3.90), ventricular arrhythmias (OR 1.91; 95% CI 1.10 to 3.31), and atrial fibrillation (OR 2.27; 95% CI 1.14 to 4.51).

CONCLUSIONS

Patients with acutely exacerbated COPD having a high risk of death can be identified at the time of admission. Variables reflecting heart dysfunction are important determinants of this risk. Among pulmonary function data, only alveolar-arterial oxygen gradient contributes to the predictive model.

Evaluation of the efficacy of pidotimod in the exacerbations in patients affected with chronic bronchitis

The efficacy and safety of pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl)carbonyl]-thiazolidine-4-carboxylic acid, PGT/1A, CAS 121808-62-6), a new oral synthetic immunostimulating agent, were investigated in a multicentre study, performed in 10 university and hospital centres of pneumophthisiology and respiratory physiopathology, according to a double-blind vs. placebo experimental design. Primary objective of the investigation was to verify the efficacy of pidotimod against infectious exacerbations in patients affected with chronic bronchitis. 181 inpatients or outpatients (117 male, 64 female; mean age: 62.5 years), affected with chronic bronchitis, were enrolled in the study. Pidotimod 800 mg/die or placebo sachets were administered by oral route for 60 consecutive days, followed by a 60-day follow-up period. Clinical observations were performed at baseline (D 0), after 30 (D 30) and 60 (D 60) days of treatment, as well as at the end of the follow-up (D 120). Time and frequency of infectious relapses were considered as the target variable for the evaluation of the efficacy of the drug. Clinical picture, expectoration characteristics, spirometric parameters and laboratory tests were monitored to evaluate patients' conditions. The results indicate that pidotimod is significantly more effective than placebo against infectious relapses in patients suffering from chronic bronchitis. During the first month, 9% of patients treated with pidotimod were affected with an infectious relapse vs. 39.5% of patients treated with placebo (chi 2, p < 0.001). In the second month, infectious episodes were reported by 1.2% of patients treated with the drug vs. 46.1% of patients treated with placebo (chi 2, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchial responsiveness in children living in areas with different air pollution levels

This study evaluated the prevalence of increased bronchial responsiveness (BR) in children living in two areas with different air pollution levels. A total of 1,215 methacholine challenge tests were performed among a random sample of primary schoolchildren in an industrial town polluted by oil-fired thermoelectric power plants and in a rural area chosen as a control. The two groups showed similar lung function data (forced vital capacity [FVC] and forced expiratory volume in 1 s [FEV1.0]) and prevalence of positive prick tests to common aeroallergens. All children responding with a 20% drop in FEV1.0 to a methacholine concentration < or = 64 mg/ml, "all responders" (PC20FEV1.0 < or = 64 mg/ml), and the subgroup of "strong responders" (PC20FEV1.0 < or = 4 mg/ml) were compared separately with "nonresponders" (PC20FEV1.0 > 64 mg/ml), calculating odds ratios (ORs). There were more "all responders" (57.2% versus 41.4%) and "strong responders" (20.0% versus 14.8%) among subjects living in the industrial area; the excess remained when several potential confounders were taken into account ("all responders": OR = 2.0, 95% confidence interval [95% CI] = 1.5-2.6; "strong responders": OR = 1.9, 95% CI = 1.3-2.8), and it was even more pronounced among girls. When the effect of clinical predictors of increased airways responsiveness (history of asthma, allergic rhinitis, baseline airways caliber, skin reactivity, recent respiratory infection) was considered through multiple logistic regression, the odds ratios associated with living in the industrial area were still significantly increased in girls. The cross-sectional approach and the lack of individual exposure data limit the interpretation of the findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Passive smoking as a determinant of bronchial responsiveness in children

The effect of passive smoking on the degree of nonspecific bronchial responsiveness (BR) in children was evaluated. In a cross-sectional survey of primary school children (7 to 11 yr) in Latium (Italy), a total of 1,215 methacholine challenge tests was performed. The children were divided into nonresponders (PC20 FEV1 > 64 mg/ml) and responders (PC20 FEV1 < or = 64 mg/ml), the latter including a subgroup of strong responders (PC20 FEV1 < or = 4.0 mg/ml). The role of passive smoking exposure was analyzed through logistic regression models. Higher odds ratios were found among girls (for strong responders: maternal smoking, OR 2.92; paternal smoking, OR 2.59); moreover, among girls there was a dose-response relationship with the number of cigarettes smoked by the mother. An effect modification was also detected for father's education and household crowding: maternal and paternal smoking were strong predictors of bronchial hyperresponsiveness in families in which the head was less educated and in overcrowded houses. The results were confirmed using a continuous index of BR (slope) and after adjustment for baseline airway caliber. We suggest that the effect of parental smoking on children's bronchial responsiveness is detectable when the conditions for a higher exposure level at home are met; females seem to be more susceptible.

Bronchial asthma: still an inadequately assessed and improperly treated disease

In this paper we present data on the assessment and treatment of asthma in a large sample (13,899 subjects) representative of the population of young males living in four districts of the Tuscany region (Italy). In this group, 404 asthmatics (2.9%) were identified and 365 of the eligible patients were included in the study. A total of 323 asthmatics (88.5%) reported respiratory symptoms during the preceding year. A total of 162 asthmatics (44%) had previously had lung function tests to assess asthma, whereas in 89% of the patients the atopic component of asthma had been previously evaluated by prick tests. Fifty-seven percent of the patients in whom bronchial obstruction was observed and 38% of the asthmatics with severe bronchial hyperresponsiveness (BH) were receiving either no medication or treatment with only one drug. The drugs prescribed most frequently during the preceding year were beta agonists (56%) as opposed to sodium cromoglycate (22%) and inhaled steroids (17%); the latter two drugs were included in the therapy of 143 asthmatics (39%) and represented the treatment of choice in 16% of the subjects with bronchial obstruction and in 38% of the subjects with severe BH. We conclude that in our sample of young asthmatics the pulmonary function tests and the inhaled anti-inflammatory drugs were insufficiently utilized.

The relationship between sporting activity and smoking habits in young adults

The authors investigated the relationship between sporting activity and smoking habits in young Italian men. One thousand, one hundred fifty-three men, age 20 years, completed a self-administered questionnaire on their smoking habits and sporting activity patterns. Five hundred sixty subjects (53%) were found to be smokers, with a high prevalence of heavy smokers (33.6%). Four hundred sixty-four (44%) of the examined subjects were sportsmen. In the group of young men not engaged in sports, the rate of smokers was significantly higher. Non-sportsmen started smoking earlier than sportsmen, and the prevalence of heavy smokers was significantly higher in the non-sportsmen group than in the sportsmen group. Finally, the young men not engaged in sports were more likely to be habitual smoke inhalers than sportsmen. These results suggest that sporting activity may indirectly influence smoking habits.

Effects of environment on atopic status and respiratory disorders in children

BACKGROUND

We investigated whether living in areas with higher air pollution levels increases the prevalence of positive skin reactivity in children and the possible synergic effect of air pollution exposure and atopy on respiratory disorders.

METHODS

This cross-sectional study was conducted in an urban area, in an industrialized area, and in a rural control area in the Latium region of Italy. A total of 2226 subjects, aged 7 to 11 years, were studied.

RESULTS

The prevalence of children with positive skin test results did not vary significantly over the areas (urban area = 21.0%, industrialized area = 22.0%, rural area = 20.2%). Children living in polluted areas experienced significantly more cough and phlegm (odds ratio [OR] = 1.5), rhinitis (OR = 1.7), pneumonia (OR = 1.7), and early respiratory infections (OR = 1.4) than control subjects. The pattern of the odds ratios for atopy and air pollution suggested that the two factors were probably additive in affecting asthma and early respiratory infections (synergy index [SI] = 1.04 and 1.27, respectively), whereas they seemed to act synergically in regard to cough and phlegm (SI = 1.59), rhinitis (SI = 3.01), and pneumonia (SI = 2.75).

CONCLUSION

Environmental air pollution seems not to increase the prevalence of atopic status; it seems, however, to enhance the development of clinical symptoms among already sensitized subjects.

An uncommon case of brainstem tumor with selective involvement of the respiratory centers

We report a clinical case of a young man with a brainstem tumor with a stable alveolar hypoventilation syndrome as the only symptom of the disease. The ventilatory response to CO2 was almost absent and the ventilatory pattern during tidal breathing was very irregular. The diagnosis was made by magnetic resonance imaging of the brain and confirmed by a stereotactic brain biopsy specimen.

Population values of lung volumes and flows in children: effect of sex, body mass and respiratory conditions

The functional relationship of gender, anthropometric measures and respiratory condition in predicting respiratory function in children was explored, using data collected in a random sample survey in Central Italy (2,176 subjects). Regression equations for the logarithmic transformation of the functional data were obtained, using sex, ln(height), ln(body mass index) (BMI) and ln(age) as predicting variables. The fit of the model was better for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) (R2 = 0.655, 0.603 and 0.312, respectively) than for maximal expiratory flows. Variables indicating the presence of respiratory conditions (recent respiratory infections, asthma, cough and/or phlegm) were forced in the models; only a marginal change in the predictions was observed. Data analysis while controlling for FVC, as a proxy for total lung capacity, revealed no substantial sex difference in airways; furthermore, airways size relative to lung size falls with increasing FVC in both sexes. In overweight subjects (BMI greater than 90th percentile) the relationship between height and lung volume was modified by sex, the coefficient for ln(height) being higher in girls and lower in boys. A comparison between equations from the present study and available reference data revealed that our population differs from standards derived from laboratory data and is more similar to those derived from population studies.

[The nonspecific bronchial stimulation test with methacholine and an ultrasonic mist of distilled water: which is to be preferred in the military sphere?]

The authors compare the methacholine (Mch) and the nebulized ultrasonic distilled water (NUDW) bronchial challenge as regard sensitivity and time required to perform them. For military service fitness, were studied 24 asthmatic patients. Each subject performed random a bronchial challenge by Mch (Yan method) and by NUDW (Allegra method) in two different days; for each bronchial challenge has been measured the time required to perform it. The atopic status has been evaluated by skin-prick test. All the subjects have shown a positive response to Mch test (PD 20 FEV1 mean: 352 mcg, range 80-850) whereas 13 subjects (54%) have shown a positive response to NUDW. The time required to evaluate all the subjects by Mch test has been 199.5 minutes whereas the total time required to evaluate all the subjects by NUDW test (127 minutes) and to evaluate by Mch test the non responders to NUDW (100 minutes) has been 227 minutes. The most of subjects were skin reactors. No difference was found as regard onset of disease, basal lung function and atopic status between responders and non responders to NUDW test. We conclude that NUDW test has shown a lack of sensitivity in this sample (50% of asthmatic patients could be misdiagnosed) and that the Mch test is preferable to determine a rapid method for measurement of bronchial responsiveness.

Population values of lung volumes and flows in children: effect of sex, body mass and respiratory conditions

The functional relationship of gender, anthropometric measures and respiratory condition in predicting respiratory function in children was explored, using data collected in a random sample survey in Central Italy (2,176 subjects). Regression equations for the logarithmic transformation of the functional data were obtained, using sex, ln(height), ln(body mass index) (BMI) and ln(age) as predicting variables. The fit of the model was better for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) (R2 = 0.655, 0.603 and 0.312, respectively) than for maximal expiratory flows. Variables indicating the presence of respiratory conditions (recent respiratory infections, asthma, cough and/or phlegm) were forced in the models; only a marginal change in the predictions was observed. Data analysis while controlling for FVC, as a proxy for total lung capacity, revealed no substantial sex difference in airways; furthermore, airways size relative to lung size falls with increasing FVC in both sexes. In overweight subjects (BMI greater than 90th percentile) the relationship between height and lung volume was modified by sex, the coefficient for ln(height) being higher in girls and lower in boys. A comparison between equations from the present study and available reference data revealed that our population differs from standards derived from laboratory data and is more similar to those derived from population studies.

Effects of environment and passive smoking on the respiratory health of children

A cross-sectional survey was conducted to evaluate the possible effects of outdoor air pollution and of parental smoking on the respiratory health of children. A total of 3092 primary schoolchildren living in two polluted areas (an industrial town, Civitavecchia, and the city of Rome) and in a rural area, were chosen. A self-administered questionnaire was filled in by the parents of 2929 children (94.2%). A broad spectrum of respiratory symptoms and illnesses were taken as outcome variables. The frequency of most outcome variables was higher among children from the polluted areas than among those growing up in the non-polluted area (e.g. asthma: odds ratio (OR) = 1.4 for Civitavecchia, OR = 1.3 for Rome). Exposure to any passive smoking increased OR of having night cough (OR = 1.8), snoring (OR = 1.4), and respiratory infections during the first 2 years of life (OR = 1.3). A further increase in risk was observed in children whose mothers smoked or if both parents were smokers (asthma, OR = 1.5). When the separate and joint effects of the two exposures were studied, the patterns of OR did not suggest synergism between the two factors. The study indicates that both air pollution and passive smoking cause an increase in respiratory symptoms in children, although there would seem to be no additional effects of the two exposures together.

Associations between atopy, asthma history, respiratory function and non-specific bronchial hyperresponsiveness in unselected young asthmatics

We evaluated the relationship between bronchial hyperresponsiveness and atopic status, clinical symptoms and airway calibre in a group of Italian conscripts who reported having bronchial asthma. 126 subjects were studied. Bronchial responsiveness was measured by the methacholine test, and atopic status was assessed by skin tests. A measurable PC20 was detected in 106 subjects. On the basis of the methacholine threshold concentration the sample was divided into four categories. Subjects with a low threshold response had an earlier onset of the disease and tended to take more drugs. The four categories also differed in lung function and skin reactivity towards Dermatophagoides pteronyssinus whereas no difference was found in skin reactivity towards grasses or the overall panel of tested allergen extracts. In conclusion, we found that bronchial hyperresponsiveness is related to both clinical history and lung function, whereas the relationship with atopic status seems to be allergen specific.

[The measurement of bronchial hyperreactivity for military service fitness]

The authors discuss the efficacy of methacholine challenge to discriminate fit subjects to military service. We evaluated the relation between bronchial hyperreactivity and clinical symptoms, airways caliber and atopic status in a group of italian conscripts who reported to have bronchial asthma. Five-hundred-four subjects were studied. Bronchial hyperreactivity was measured by methacholine test, and atopic status was assessed by skin-tests. A measurable PC20 FEV1 was detected in 424 subjects. On the basis of the methacholine threshold concentration the overall sample was divided in four categories. The four categories differed as regards onset of disease, lung function and skin reactivity towards Dermatophagoides Pter, whereas no difference was found as regards skin reactivity towards Grass. In the group evaluated in spring, the four categories differed as regards skin reactivity towards Grass. In conclusion we found that bronchial hyperreactivity is related to clinical history, lung function and atopic status; the measurement of bronchial hyperreactivity is important to evaluate conscripts referring bronchial asthma.

[Marked hematic hypereosinophilia caused by Giardia Lamblia infestation in a subject with Churg-Strauss syndrome]

We report a Churg-Strauss syndrome case complicated by Giardia Lamblia infection which increased markedly the number of blood eosinophils with appearance of eosinophils able to form rosettes with unsensitized sheep red blood cells. Metronidazolo therapy reduces markedly the blood hypereosinophilia. The strong relationship between blood hypereosinophilia and Giardia Lamblia in this patient, suggests that there is an interaction between different eosinophilopoietic stimuli.

Indices of nonspecific bronchial responsiveness in a pediatric population

A cross-sectional survey of the prevalence of asthma and bronchial hyperreactivity among schoolchildren (7 to 11 years old) was carried out in three areas of the Latium region (Central Italy). Out of 1,777 children tested with methacholine challenge (MCT), 15.1 percent had a 20 percent fall in FEV1 after a provocative concentration (PC20FEV1) of 4 mg/ml of methacholine or less; 69.7 percent had a PC20FEV1 less than 64.0 mg/ml, whereas 50.3 percent were nonresponders. Two continuous measures of bronchial responsiveness, the slope (percentage of change in FEV1 per mg/ml of methacholine) and the area under the dose response curve, were calculated in order to avoid the loss of information in nonresponders. Applying a receiver operating characteristic (ROC) curve analysis, the three estimators did not show any statistically significant difference in their overall performance in detecting asthma (ROC areas: PC20FEV1 = 0.683, slope = 0.681, area = 0.702 or asthma-like symptoms. The log transformation of slope, having a unimodal and slightly skewed shape, is an appealing continuous measure of bronchial responsiveness useful for epidemiologic studies. The final choice of an appropriate estimator of the concentration-response curve to methacholine, however, depends upon both the statistical tests or the modelling procedures to be used and clarification of the prognostic value of different indices of bronchial responsiveness.

Bilateral bronchoalveolar lavage in progressive systemic sclerosis: interlobar variability, lymphocyte subpopulations, and functional correlations

Bilateral bronchoalveolar lavage (BAL) was carried out in right middle and left upper lobes of 22 nonsmoking females suffering from progressive systemic sclerosis in order to assess interlobar differences and functional correlation of the BAL composition. The patients' age ranged from 20 to 66 years, and the mean disease duration was 10.4 years. The most frequent finding was a mild BAL lymphocytosis (right in 11 of 22 patients; left in 8 of 22), but eosinophilic (right in 11 of 22; left in 5 of 22 patients) and neutrophilic (right in 9 of 22 patients; left in 1 of 22) alveolitis was recognized as well. Differential counts suggestive of alveolitis limited to one of the lavaged lobes were demonstrated in about one fourth of the cases. Including increased cellularity among the criteria of pathological BAL fluid composition, 14% of the subjects showed bilateral BAL results within the normal range. OKT8-positive lymphocytes were significantly increased in 3 patients, but the mean values were not. Total lung capacity, vital capacity, and forced expiratory volume in 1 s correlated inversely with BAL neutrophil (p less than 0.05) and granulocytic (p less than 0.01) differential counts; the strongest, positive correlation was demonstrated regarding the lymphocyte/granulocyte ratios (p less than 0.0005). In conclusion, several patterns of alveolitis as well as a bilaterally normal BAL composition were found in our series; moreover, even if inhomogeneous alveolitis did occur, a single lavage performed in the right middle lobe correctly detected or excluded the presence of an alveolitis in 95% of our patients.

Factors affecting variations in pulmonary diffusing capacity resulting from postural changes

The relation of postural changes to the diffusing capacity of the lung for carbon monoxide (DLCO) was investigated in 12 normal nonsmokers in order to evaluate the influence of body position on several components of lung resistance to gas diffusion. The well-known increase in CO diffusing capacity in the supine position was obtained only for data corrected for alveolar volume (KCO: 6.18 +/- 0.75 vs. 5.45 +/- 0.67 ml/min/mm Hg/l; p less than 0.005). Moreover, only the membrane component (Dm) increased significantly in supine subjects (KDm = 2.81 +/- 1.32 vs. 1.82 +/- 0.54 ml/min/mm Hg/l; p less than 0.05), the increase in capillary blood volume (Vc) being not significant (KVc = 12.54 +/- 4.22 vs. 11.17 +/- 3.79 ml/l; NS). These data could be interpreted as a demonstration of a more homogeneously distributed ventilation with respect to diffusion surface in healthy young people in a supine position. The amount of surface available for diffusion seems therefore to be a limiting factor to gas flow across the lungs in these subjects. Thus a straightforward attribution of posturally influenced changes in CO diffusing capacity exclusively to factors affecting Vc is not recommended, particularly in pathological conditions, if information about variation in distribution of ventilation is unavailable.

Bronchial hyperresponsiveness in atopic dermatitis

We investigated the prevalence of bronchial asthma, immediate skin reactivity and bronchial hyperresponsiveness in 40 patients with atopic dermatitis (AD). Eight patients reported to have asthma while 29 were found responders to methacholine test (PC20 Mch less than 64 mg/ml) and 21 were skin reactors. The prevalence of skin positive reactions did not differ in responder and non-responder (PC20 Mch greater than 64 mg/ml) groups. Males were more likely both to have bronchial asthma and be responders to methacholine test than females. Moreover, responders had an earlier age of onset of AD than the non-responders. We suggest that bronchial responsiveness should be evaluated in children with AD.

Comparison of the performance of two mini peak flow meters

Two mini peak flow meters commonly used to monitorize the peak expiratory flow rate (PEFR) are compared to assess their agreement, precision and, with respect to a standard pneumotachygraph, accuracy. Precision of the mini-Wright peak flow meter is greater, possibly as result of a systematic overestimation of PEFR values. The Assess peak-flow meter is more accurate, but its ability to reproduce the actual well-known PEFR variability is dependent from the absolute level of air flow. The agreement between two instruments is very poor, both in asthmatics and in normals, so that it is mandatory to use always the same mini peak flow meter in population studies and during the follow-up of asthmatic patients.

Probit analysis applied to the allergen dose-response curve: a method for epidemiologic surveys

The degree of skin sensitivity to five common allergens (grass, Dermatophagoides pteronyssinus, mugwort, birch, and Parietaria) was determined by the threshold dilution technique in all the skin test reactors of a random sample of 295 schoolchildren (142 male and 153 female subjects, age range 11 to 14 years), and the frequency distribution of responders at each concentration was analyzed by probit analysis. The potency of each allergen was presented in terms of median effective dose (ED50), and comparison between different allergens and between symptomatic and asymptomatic subjects was made by computing the relative potency. The ED50 of the allergens was found to be nearly identical (grass, 13.5; D. pteronyssinus, 12.3; mugwort, 9.6 activity units by RAST (AUR)/ml) with the exception of birch (22 AUR/ml). Grass and D. pteronyssinus demonstrated a lower ED50 in symptomatic subjects (3.3 and 2.8 AUR/ml, respectively) than in asymptomatic subjects (85 and 27 AUR/ml, respectively). The lower fiducial limits of ED50 in symptomatic subjects demonstrated to be a cutoff point, since they included only 5% and 12% of asymptomatic reactors to grass and D. pteronyssinus, respectively. We conclude that probit analysis applied to the distribution of threshold doses of allergen extracts is a useful method to evaluate skin sensitivity in epidemiologic surveys. We believe that the ED50 is a practical and reliable allergy index.

Effects of two doses of cromolyn on allergen-induced late asthmatic response and increased responsiveness

We selected five atopic children with asthma with previously documented late asthmatic response (LAR) associated with increased hyperresponsiveness to methacholine after the inhalation of Dermatophagoides pteronyssinus. The children had four allergen inhalation tests on 4 different days, at least 14 days apart. On days 1 and 4, saline placebo was inhaled 1 hour before the expected onset of LAR, and FEV1 was measured hourly until FEV1 returned within 10% of baseline value; then methacholine challenge was performed. On days 2 and 3, 20 and 40 mg of cromolyn was inhaled double blind 1 hour before the expected onset of LAR. FEV1 and methacholine responsiveness were measured as on days 1 and 4. The two doses of cromolyn significantly delayed the LAR onset without altering the overall LAR magnitude and prevented the allergen-induced increase in methacholine responsiveness. Both these effects were greater at the maximal dose used. We conclude that cromolyn can prevent the allergen-induced increase in methacholine responsiveness and that this effect is not due to alteration in the magnitude of LAR. Our findings reveal a possible explanation of the effectiveness of this drug in the treatment of allergic asthma.

The effect of indomethacin on the refractory period occurring after the inhalation of ultrasonically nebulized distilled water

We examined the involvement of inhibitory prostaglandins in refractoriness induced by repeated ultrasonically nebulized distilled water (UNDW) challenge. Six male subjects with asthma who developed both UNDW-induced bronchoconstriction and refractoriness after UNDW were studied on 3 separate days, 1 week apart. On each study day, subjects had an initial UNDW challenge. UNDW responsiveness was assessed with dose-response curves of UNDW volume output versus the percent fall in FEV1. The output provoking a 20% fall in FEV1 (PO20 UNDW) was calculated. FEV1 was measured again at 5-minute intervals until it returned to within 5% of baseline value. UNDW challenge was then repeated. On day 1, the two successive UNDW challenges were performed in absence of any treatment (control day). Before days 2 and 3, subjects received placebo capsules or indomethacin, 100 mg per day, in a double-blind, randomized fashion for 3 days. On both the control and placebo days, repeated UNDW inhalation provoked a significant increase in PO20 UNDW (p less than 0.01), indicating refractoriness. On the indomethacin day, the mean PO20 UNDW during the second UNDW challenge was not significantly different from that obtained during the initial test on that day (p greater than 0.05), indicating that refractoriness did not occur. We suggest that inhibitory prostaglandins are involved in the development of refractoriness after UNDW inhalation.

Allergy indices based on allergen dose-response curve in a randomly selected sample of schoolchildren

Skin-test sensitivity was computed in 61 schoolchildren drawn from a stratified random sample in order to generate two allergy indices based on a quantitative skin-test assay: Individual Allergy Index (IAI) and Population Allergy Index (PAI). The former to quantitate IgE-mediated skin test sensitivity of each subject, the latter to describe the degree of skin reactivity of our sample to a single allergen. Five allergen extracts were tested at 4-fold dilutions. Sensitivity endpoint data were used to generate IAI. Frequency distribution of IAI seemed to be bimodal as asymptomatic subjects gathered at the lower part while symptomatic children showed a peak in the middle. By means of criteria based on the relation between IAI and the prevalence of symptoms we were able to classify atopy in five classes from normal (all asymptomatic subjects) to severe atopy (all symptomatic subjects). Each positive reaction was plotted as a function of the allergen concentration eliciting the weal, and linear regression with confidence limits was calculated for grass and Dermatophagoides pteronyssinus only. PAI was represented by the slope, which depends on the reactivity of the sample, and the intercept, which involves the potency of the allergen as well. Grass and D. pteronyssinus showed the same slope while the intercepts differed. The slope increased if we considered symptomatic subjects only. We propose both these indices for clinical and epidemiological studies.

Effect of two doses of inhaled diltiazem on exercise-induced asthma

Seven asthmatic children with moderately to severely increased bronchial responsiveness to methacholine took part in a double-blind placebo-controlled study to assess the effect of a calcium channel blocker, diltiazem, on exercise-induced asthma (EIA), and its duration. On the control day, bronchial response to exercise was found to be highly reproducible when performed 2 h apart (intraclass correlation coefficient 0.92). Normal saline and diltiazem at concentrations of 1.75 and 3.50 mg/ml (estimated nebulized doses 5 and 10 mg, respectively) were given in random order before exercise on a bicycle ergometer. Exercise challenge was performed 20 min and 2 h after each treatment, and bronchial response was expressed as percent fall in the forced expiratory volume in 1 s. In the overall group, diltiazem did not significantly change resting bronchial tone and produced no significant (p = 0.18) attenuation of EIA. An almost complete protection was detected only in two subjects 20 min after diltiazem 10 mg. This limited effect waned 2 h after the administration.

Comparison of bronchial responses to ultrasonically nebulized distilled water, exercise, and methacholine in asthma

We compared the responses to inhaled methacholine, ultrasonically nebulized distilled water, and exercise in 25 subjects with atopic asthma. The methacholine inhalation test and challenges with distilled water and exercise were performed on three separate days 48 hours apart. Bronchial responsiveness to methacholine and ultrasonically nebulized distilled water was measured as the concentration of methacholine (PC20M) and the volume output of the ultrasonic nebulizer (PO20 UNDW) producing a 20 percent fall in the forced expiratory volume in one second (FEV1). The response to exercise was expressed as the percentage of fall in FEV1 from the value before exercise. Seventeen subjects showed a fall in FEV1 of more than 20 percent after exercise. Eight subjects had a stimulus-response curve to distilled water that was flat up to the maximal volume output from the nebulizer, but only four of them also showed no significant response to exercise. The response to exercise correlated better with PO20 UNDW (r = -0.66; p less than 0.01) than with PC20M (r = -0.19; p greater than 0.5) in those responding to distilled water. In all of the tested subjects, exercise-induced bronchoconstriction correlated with PC20M (r = -0.61; p less than 0.01). The mean PC20M was significantly lower in the subjects with a significant response to distilled water and exercise (p less than 0.001 and p less than 0.0001, respectively). We concluded that ultrasonically nebulized distilled water and exercise provoke significant bronchoconstriction in the subjects with more severe nonspecific bronchial hyperresponsiveness. The correlation found between the two stimuli supports the hypothesis that they act by similar mechanisms.

Late bronchial response and increase in methacholine hyperresponsiveness after exercise and distilled water challenge in atopic subjects with asthma with dual asthmatic response to allergen inhalation

We investigated the occurrence of late asthmatic response and increased methacholine responsiveness after exercise and ultrasonically nebulized distilled water (UNDW) inhalation in 12 subjects with asthma with dual asthmatic response and increased responsiveness after allergen challenge. On 3 separate days, allergen, exercise, and UNDW challenges were performed 2 hours after methacholine. FEV1 was measured for 8 hours to detect any delayed change in airway caliber. If there were a further significant reduction in FEV1 after the recovery from the immediate bronchoconstriction, methacholine challenge was performed again when FEV1 had returned to baseline. Reproducibility of any observed late response to exercise and UNDW was also investigated by repeating these challenges on 2 subsequent days. After allergen inhalation only nine subjects had an early asthmatic response, whereas all the tested subjects demonstrated a late reaction and increased methacholine responsiveness. Ten subjects had an immediate response to exercise, and this was followed by a late response in only four patients. Nine subjects demonstrated early response to UNDW inhalation, and five subjects also had a late reaction. These late responses were associated with an increase in methacholine responsiveness in a subset of the tested subjects. Late-phase reactions to exercise and UNDW were not reproducible.

Increase in bronchial responsiveness to methacholine and late asthmatic response after the inhalation of ultrasonically nebulized distilled water

We studied ten subjects who had an asthmatic response after the inhalation of ultrasonically nebulized distilled water and did not show any refractory period to repeated challenge with such water. The change in responsiveness to methacholine after inhalation of distilled water and the occurrence of any water-induced late asthmatic response were investigated on separate days. All of the tested subjects showed a significant increase in bronchial responsiveness to methacholine after prior stimulation with ultrasonically nebulized distilled water, which waned within two hours in eight of them. The other two subjects showed a progressive increase in responsiveness to methacholine, and they also had a further reduction in the caliber of the airways three to four hours after inhalation of distilled water. The late responses were less severe than the initial responses and lasted four to five hours. After the spontaneous recovery, no significant increase in responsiveness to methacholine was detected. Our results confirm previous observations on hyperresponsiveness induced by ultrasonically nebulized distilled water and demonstrate the occurrence of late reactions after inhalation of such water.

Protective effect of disodium cromoglycate on allergen-induced bronchoconstriction and increased hyperresponsiveness: a double-blind placebo-controlled study

The protective effect of 40 mg cromolyn on allergen-induced late response and increased hyperresponsiveness were studied in five asthmatic children to whom this drug and saline placebo were administered 20 minutes before allergen inhalation, at random, double-blind. Cromolyn reduced the magnitude of early and late responses and abolished the increase in methacholine responsiveness.

Dose-response relationship: fenoterol, ipratropium bromide and their combination

The beta agonist fenoterol, the antimuscarinic ipratropium bromide and their combination were compared in 10 patients with stable reversible airway obstruction. A single-blind cross-over design was used in order to obtain cumulative dose-response curves. The dose inhaled by an IPPB apparatus on different days were: fenoterol, from 12.5 to 1.600 cumulate micrograms; ipratropium bromide, from 5 to 640 cumulate micrograms; combination (5:2), from 17.5 to 1.120 cumulate micrograms. The bronchodilator effect was measured as changes of FEV1 and of SGaw. Data were processed in order to identify the median effective dose (ED50) and the percentage change at ED50 (RED50). The mean ED50 in micrograms (+/- SD) resulted in: Fenoterol, ED50 (FEV1) = 132 (+/- 46); ED50 (SGaw) = 172 (+/- 62); Ipratropium bromide, ED50 (FEV1) = 14 (+/- 7); ED50 (SGaw) = 23 (+/- 11); Combination, ED50 (FEV1) = 109 (+/- 26); ED50 (SGaw) = 121 (+/- 53). The mean RED50% (+/- SD) resulted in: Fenoterol, RED50 (FEV1) = 30 (+/- 16); RED50 (SGaw) = 106 (+/- 78); Ipratropium bromide, RED50 (FEV1) = 21 (+/- 10); RED50 (SGaw) = 82 (+/- 66); Combination, RED50 (FEV1) = 35 (+/- 11) RED50 (SGaw) = 135 (+/- 81). The ED50 (FEV1) of the combination was significantly lower (p less than 0.05) than that of fenoterol. This increased potency of the combination supports evidence for an overadditive interaction between fenoterol and ipratropium bromide. Moreover, the efficacy of fenoterol (RED50) is enhanced by combining the two drugs.

The immediate and short-term effects of corticosteroids on cholinergic hyperreactivity and pulmonary function in subjects with well-controlled asthma

We investigated the immediate effect of corticosteroids on pulmonary function (FEV1 and forced expiratory flow measured between 25% and 75% of vital capacity) and methacholine airway reactivity during a period of 8 hours after an intravenous bolus of 6-methyl-prednisolone (1 mg/kg) or saline placebo administered in a double-blind, crossover schedule in 12 patients with well-controlled asthma. The short-term effect of corticosteroids was also studied with bronchial reactivity to methacholine and pulmonary function measured before and at the end of 8 days of 6-methyl-prednisolone therapy (32 mg once a day, orally) in a group of six treated subjects as well as in a control group. There were no immediate or short-term effects from 6-methyl-prednisolone on bronchial response to inhaled methacholine. After 8 days of corticosteroid administration, forced expiratory flow measured between 25% and 75% of vital capacity significantly increased in the treated group (p less than 0.025). We concluded that "primary hyperreactivity" appears to be insensitive to an intravenous bolus or 8 days of treatment with oral corticosteroids and that the improvement in respiratory function is slight and slowly evolving in subjects with well-controlled asthma.

A simple method of predicting left ventricular function in stabilized chronic respiratory failure

A simple method of assessing left ventricular function in stabilized chronic respiratory failure (CRF) is proposed. 21 patients with CRF were ranked according to the prediction of left ventricular function derived from eight elementary clinical criteria including standard chest X-ray and conventional basal electrocardiography. Equilibrium radionuclide angiocardiography was performed at rest (rERNA) for the evaluation of left ventricular systolic function (ejection fraction, LVEF; peak ejection rate) and diastolic function (peak filling rate). Right ventricular ejection fraction (RVEF) was also measured. The clinical evaluation of the left ventricular function showed a high correlation with rERNA data (p less than 0.01 by Spearman's rank test). No correlation was found between rERNA parameters and PaO2 and between RVEF and LVEF. The clinical criteria proposed can thus predict left ventricular function in stabilized CRF with a high degree of confidence.

Detection of ventilation unevenness by nitrogen washout and forced vital capacity manoeuvres: its limits and reliability

We investigated the behaviour of several indices of ventilation unevenness in a sample of 234 normal subjects aged between 20 and 80 years, divided into 12 classes of 5 years each. The aim of the present study was to find out whether it is possible to predict a reliable value for each of these indices as a function of age, height and TLC. For each index a large dispersion of experimental points and a high unexplained variance was found, so that it does not seem worthwhile predicting its value as a function of age, height and TLC. We concluded that there is no reason to employ these indices to detect the beginning of a lung function impairment.

Respiratory function during pregnancy

We studied the respiratory mechanics, acid-base status, alveolar ventilation and ventilatory response to hypercapnia in pregnant women at the first and third trimesters and postpartum. We found alveolar hyperventilation and hypersensitivity of the respiratory centers to carbon dioxide with no significant differences between the first and third trimesters. After delivery we found a sudden decrease in these parameters. The changes seem to be due to a direct primary (probably hormonal) stimulation on the medulla oblongata and cannot be correlated to the metabolic needs of the fetus and are aimed at favoring placental gas exchanges, especially at the beginning of the pregnancy, when the fetal cardiovascular system is not yet developed.

Chronobiological aspects of bronchial tone

The aim of the investigation was to demonstrate the existence of cyclic variations of bronchial tone, correlated with the increase of vagal tone during nocturnal hours and with the increase of adrenergic tone in the late morning and afternoon. Twenty-five healthy subjects were tested, utilizing forced expiration curve (V/V loop), Raw and SGaw. We did not detect a statistically significant rhythm for FVC, FEV1, PEF, because they are effort-dependent parameters. On the contrary, we demonstrated significant fluctuations for V max50, FEF25.75 (acrophase in the later morning and early afternoon), for Raw (acrophase in late evening) and for SGaw (Acrophase in antiphase with Raw); these parameters are effort-independent as well as direct and sensitive indexes of the tone of peripheral and central airways.

[Computer evaluation of hemodynamic changes during mechanical ventilation with a body respirator]

The Authors study the variations of the cardiac output (C.O.), of the mean pulmonary arterial pressure (mPAP) and of the pulmonary vascular resistance (P.V.R.) in fine patients, affected by chronic respiratory failure, during the mechanical ventilation with a body respirator. In all the patients a reduction of the mPAP and of the CO are present. The PVR varies proportionally to the improvement of the respiratory indices. The Authors conclude that the haemodinamic changes are not exclusively due to the mechanical effect of the body respirator, but also to the correction of the respiratory situation and particularly due to the intra-alveolar pressure.