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PubMed1984

Sensitivity and specificity of the computational model for maximal expiratory flow.

The computational model for forced expiratory flow from human lungs of Lambert and associates (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 52: 44-56, 1982) was used to investigate the sensitivity of maximal expiratory flow to lung properties. It was found that maximal flow is very sensitive to recoil pressure and airway areas but not very sensitive to lung volume, airway compliance, and airway length. Linear programming was used to show that a given air flow-pressure curves was compatible with a fairly wide range of airway properties. Additional data for maximal flow with a He-O2 mixture narrowed the range somewhat. It was shown that the flow-pressure curve contains more information about central than peripheral airways and that information about the latter is obtainable only from flows at recoils less than 2 cmH2O. Parameter ranges compatible with individual flow-pressure curves showed differences that demonstrated that such curves give some indication of individual central airway properties.

Airway Resistance↗
PubMed1976

Measurement of plasma prostaglandins during exercise-induced bronchospasm.

Bronchospasm following exercise is a phenomenon which occurs in most patients with reversible airway disease. The pathophysiologic mechanism leading to this bronchoconstriction with exercise has not yet been defined. Recently, prostaglandins have been implicated in the etiology of asthma. The purpose of this investigation was to determine changes in plasma prostaglandins occurring during exercise-induced asthma. Eight ambulant asthmatics were chosen for baseline pulmonary spirometry and peripheral venous blood prostaglandin E and F levels. The asthmatics were then exercised to 80% of their age-predicted maximal heart rate via a multistage branching treadmill protocol. At 5, 15, and 30 min following exercise, pulmonary spirometry was again performed and peripheral venous blood collected at the indicated times. Clinical bronchospasm as characterized by audible wheezing and greater than 15% decrease in FEV1 and MMEFR was obtained in all of the asthmatics. Peripheral PGE and PGF2alpha determinations following this exercise protocol were not altered significantly: (PGE: 0 min, 238; 5 min, 185; 15 min, 248; 30 min, 256 pg/ml); (PGF2alpha: 0 min, 50; 5 min, 24; 15 min, 25; 30 min, 17 pg/ml) (p less than 0.1). In summary, no significant change in peripheral blood prostaglandin E and F2alpha levels as determined by radioimmunoassay was noted at the time of exercise-induced bronchospasm.

Bronchial Spasm↗
PubMed1989

Airway pressure-volume curve estimated by flow interruption during forced expiration.

We attempted to estimate the pressure-volume characteristics of airways downstream from the choke point when the airflow was abruptly interrupted during forced expiration. The change of gas volume of the downstream segment after interruption could be estimated by multiplying the maximum flow (Vmax) immediately before interruption by the interruption time because the Vmax is maintained for a short period after airflow interruption at the mouth, as described in our previous report (J. Appl. Physiol. 66: 509-517, 1989). For the pressure of the downstream segment, we used the mouth pressure itself. Airway compliance, a slope of the pressure-volume curve, was measured in an airway model in eight normal subjects, in six patients with chronic obstructive pulmonary disease (COPD), and in one patient with tracheobronchopathia osteochondroplastica. Airway compliance was 0.96 ml/cmH2O in normal subjects and 2.49 ml/cmH2O in COPD patients. This difference of airway compliance was believed to be caused by the longitudinal expansion of the downstream segment and changes in the properties of the airway wall.

Adult↗
PubMedDate not supplied

[Maximum expiratory flow rate (peak flow) in healthy persons and patients with bronchial asthma].

Lung function tests were done on 42 patients, 22 asthmatics and 20 normal volunteers. The peak flow and expiratory flows at different levels of the forced vital capacity curve were evaluated. The flow-volume curves were obtained with a conventional spirometer, and the peak flow was determined with a Wright flowmeter. The peak flow obtained by the two methods were within the normal range, although the values registered by the Wright flowmeter were consistently lower. A reduction of the expiratory flow in the distal part of the vital capacity curve was observed in asthmatics, suggesting small airways obstruction. In conclusion, peak flow is not of use in the detection of predominantly distal airways obstruction.

Adult↗
PubMed1982

Analysis of antigen-induced changes in pulmonary mechanics in sensitized inbred rats.

An inbred line of rats was derived which develop marked and consistent dyspnea following sensitization and then exposure to aerosolized antigen. This pulmonary response was investigated in detail by determining forced pulmonary mechanics to derive respiratory rate, peak expiratory flow rate (PEFR), forced vital capacity (FVC), forced expiratory volume in 0.1 s (FEV0.1), and maximal midexpiratory flow rate (MMFR). Challenging anesthetized rats for 5 min with an aerosol of 3% egg albumin produced minimal change in respiratory rate, a 20% fall in PEFR, a 50% fall in FVC, and a 30% decrease in FEV0.1 and MMFR. The response could be inhibited or reversed by salbutamol (0.5 mg/kg, i.v.) and aminophylline (25 mg/kg, i.v.) administered either before or after challenge. The pulmonary changes are consistent with antigen-induced asthma in the rats. The response shows similarities to human asthma and may provide a relevant experimental model.

Albuterol↗
PubMed1976

Evaluation of exercise-induced bronchospasm in the adult asthmatic.

It has been shown that most asthmatics respond to exercise with bronchospasm. This study was undertaken to develop a safe and reliable method for quantifying exercise-induced bronchospasm in the asthmatic adult. Five normal adult volunteers and 12 stable asthmatics were exercised to 80% of their predicted maximal heart rate according to a multistage branching treadmill protocol. Their responses in terms of forced expiratory volume in 1 sec (FEV1) and maximum midexpriatory flow rate (MMEFR) at 5, 15, and 30 min after exercise were assessed, while standing, with a Jones Pulmonar II waterless spirometer. This submaximal stress test was chosen because 80% of predicted maximal heart rate could be obtained by all individuals and allowed the asthmatics to exercise long enough for inducible bronchospasm to occur. Audible wheezing was induced in 100% of the asthmatics and in none of the nonasthmatics. In the normal individuals, FEV1 and MMEFR increased signficantly during the postexercise period. When compared to normal subjects, the 12 asthmatic patients demonstrated a significant reduction in FEV1 an MMEFR (deltaFEV1 : 5 min, -300; 15 min, -304; o9 min, -208 ml; -18%, -17%, and -15%; deltaMMEFR: 5 min, -15; 15 min, -9; 30 min, -1L/M; -23%, -18%, and -6%) (p less than 0.01). The use of a rigidly controlled exercise stress with a cardiovascular endpoint in the measurement of FEV1 and MMEFR in the postexercise period appears to be a useful tool in assessing the presence and severity of exercise-induced bronchospasm in the adult asthmatic.

Adult↗
PubMed1975

[Action of acebutolol on heart rate and FEV1 in asthmatic patients. Single intravenous administration and long term oral administration].

In 7 asthmatic patients, intravenous injection of acebutolol resulted in a slowing of the heart rate by blocking the cardiac beta-receptors. An aerosol of isoprenaline, which accelerated the heart, is without effect after intravenous injection of acebutolol. On the contrary, isoprenaline caused similar changes in the FEV1 before and after acebutolol injection in the same patients. This effect confirms the slight action of the compound on the beta2-adrenergic receptors. Prolonged oral administration did not cause any adverse clinical effects in 6 asthmatic patients.

Acebutolol↗
PubMed1985

Increase in tracheal size with age. Implications for maximal expiratory flow.

Because mechanical properties of central airways play an important role in determining maximal expiratory flow, we examined how tracheal size and maximal expiratory flow changed with age in 50 asymptomatic men, 19 to 61 yr of age, who were lifelong nonsmokers. Cross-sectional area (X-SA) of the intrathoracic trachea was estimated from posteroanterior and lateral chest radiographs taken at full inflation. Maximal expiratory flow-volume curves and spirometry were measured by standard techniques. Tracheal X-SA averaged 2.81 cm2 (SD, 0.38) at mean age 21.1 yr and 3.22 cm2 (SD,0.41) at mean age 52.5 yr, and correlated with peak expiratory flow (PEF) (r = 0.522, p less than 0.001) and FEV1 (r = 0.437, p = less than 0.01) (both expressed as percent predicted values based on age and height). These relationships were weaker than previously described in young men. The results suggest that with increasing age, large airways lose elastic recoil, as previously described for the air spaces. Aging changes in the airways may offset the unfavorable effects of loss of lung recoil and account for the relatively good preservation of PEF and the lack of rise in airways resistance with increasing age.

Adult↗
PubMed2007

Evaluation of pulmonary function and bicycle ergometry tests in patients with Behçet's disease.

Behçet's disease (BD) has well-defined pulmonary complications, but cardiopulmonary exercise testing and the strength of the respiratory muscles have not been studied in detail. We aimed to investigate the pulmonary functions tests, inspiratory and expiratory muscle strength and endurance, cardiopulmonary exercise test response, and the relationship of these parameters in patients with BD. Forty BD patients and 20 healthy control subjects were recruited for this study. Mean age was 32.95 +/- 7.66 years for the BD group and 33.85 +/- 6.63 years for the control group with no statistically significant difference. The ratios of slight obstructive ventilatory impairment were 32.5% for the BD group. When the values of pulmonary function tests were compared, no statistically significant difference was found in FEV(1)/FVC (Forced expiratory volume during the first second/forced vital capacity), or maximal midexpiratory flow rate (all in percent) values between patient and control groups. Maximal inspiratory and expiratory pressures, peak expiratory flow rate (in percent) and maximal voluntary ventilation (in percent) values were significantly lower than those of the control group. Body's consumption of peak oxygen (VO(2peak)), oxygen consumption (milliliters per kilogram per minute), anaerobic threshold (AT), maximum exercise ventilation (VE(max)), work load values, and exercise test time in the bicycle exercise test were significantly higher in control groups than in patients with BD. The values of heart rate reserve, breathing reserve, and VE/VCO(2) at the AT of BD patients were within normal limits We conclude that respiratory and aerobic exercise may be recommended to improve respiratory muscle strength and endurance as well as the aerobic capacity and maximal ventilatory capacity in patients with BD.

Adult↗
PubMed2002

[Evaluation of systematic pulmonary function testing for asthma in children aged three to five years].

UNLABELLED: Pulmonary function testing is not usually done in the preschool child, despite the recent data showing early deterioration in airway function in asthma. METHODS: We evaluated feasibility and clinical interest of flow-volume loop by forced expiratory maneuver and measure of airway resistance by interrupter technique (interrupter resistance), before and after inhalation of salbutamol, in 75 children aged three to five years seen in the ambulatory setting for asthma. RESULTS: Feasibility rate (92%) and reproducibility rate (91%) of those techniques were good, so that 84% of the cases could be exploited (63 children of 75). We found few significant associations between clinical parameters and flow-volume loop. We found a significant association between elevated interrupter resistance at basis and night-symptoms (P = 0.03), between diminished interrupter resistance after salbutamol and exercise-symptoms (P = 0.03), symptoms in the ambulatory setting (P = 0.02) and absence of inhaled corticosteroid treatment (P = 0.046). Pulmonary function testing resulted in treatment modification in 14% of cases. CONCLUSION: Our study shows that flow-volume loop and measure of airway resistance by interrupter technique can be done with a good reproducibility in the preschool child. Interrupter resistance appears to be better correlated than flow-volume loop with usually evaluated clinical parameters.

Asthma↗
PubMed1980

Small-airways dysfunction in nonsmokers chronically exposed to tobacco smoke.

We evaluated the effect of long-term passive smoking (involuntary inhalation of tobacco smoke by nonsmokers) and long-term voluntary smoking on specific indexes of pulmonary function in 2100 middle-aged subjects. Regardless of sex, nonsmokers chronically exposed to tobacco smoke had a lower forced mid-expiratory flow rate (FEF 25 to 75 per cent) and forced end-expiratory flow rate (FEF 75 to 85 per cent) than nonsmokers not exposed (P less than 0.005). In addition, values in passive smokers were not significantly different from those in light smokers and smokers who did not inhale (P less than 0.005). When we looked at the extent to which smoke exposure is related to graded abnormality, we found that nonsmokers in smoke-free working environments have the highest scores on the spirometric tests; passive smokers, smokers who do not inhale, and light smokers score similarly and significantly lower; and heavy smokers score the lowest (P less than 0.005). We conclude that chronic exposure to tobacco smoke in the work environment is deleterious to the nonsmoker and significantly reduces small-airways function.

Carbon Dioxide↗
PubMed1981

Lung function changes by ethanol inhalation.

The acute effect of ethanol inhalation on ventilatory capacity was studied in a group of six healthy volunteers and the results were compared to those obtained after the inhalation of a saline solution. There was a significant decrease in flow rates on partial expiratory flow-volume (PEFV) curves up to 90 min after ethanol inhalation. FEV1 values did not change significantly, either after ethanol or saline aerosol. Pretreatment with atropine did not prevent the acute reductions in flow rates in comparison with the reductions without atropine. Pretreatment with disodium cromoglycate (DSCG) considerably diminished the acute reductions of flow rates caused by ethanol inhalation. These results suggest that ethanol in some persons may act, at least partly, through releasing mediators with bronchoconstrictive action.

Administration, Intranasal↗