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PubMed1975

Factors influencing the measurement of closing volume.

The various factors influencing closing volume were studied by performing the single-breath N2 test on 9 healthy nonsmokers. Time of day, day of the week, and preceding volume history had no effect on either closing volume or alveolar plateau. Slow inspiratory flow resulted in larger ratio of closing volume to vital capacity, ratio of closing capacity to total lung capacity, and change in N2 concentration than fast inspiratory flow. Voluntary regulation of the expiratory flow resulted in smaller ratios of closing volume to vital capacity and closing capacity to total lung capacity than when flow was regulated by a resistance. Prolonged breath holding of the inspired O2 led to larger ratio of closing volume to vital capacity and ratio of closing capacity to total lung capacity. To obtain uniform, comparable closing volumes, it is suggested that the subject inspire slowly, control expiratory flow (preferably voluntarily), and not pause between inspiration and expiration.

Adult↗
PubMed1989

Alveolar pressure and airway resistance during maximal and submaximal respiratory efforts.

A digital computing technique was used to extract continuous calculations of average alveolar pressure and airway resistance from body plethysmographic measurements during forced inspiratory and expiratory vital capacity maneuvers and tidal breathing in human subjects. Derived alveolar pressures were similar to those obtained using an interrupter technique (linear regression slope, 0.99 +/- 0.02; r = 0.98) and by comparison with esophageal pressure measurements. Studies in normal subjects revealed a characteristic pattern of increasing airway resistance throughout the expiratory phases of maximal and submaximal respiratory maneuvers, with maximal resistance of 33 to 110 cm H2O/L/s at low lung volumes during forced vital capacities. In contrast, inspiratory resistance remained low and constant throughout maximal and submaximal inspiratory maneuvers. Patients with COPD showed substantially higher inspiratory and expiratory resistances. In three patients with flow-volume loops suggestive of variable extrathoracic upper airway obstruction, measurements of alveolar pressure and airway resistance made it clear that two of the patients had upper airway obstruction, whereas the other was exerting an inadequate effort. We conclude that this noninvasive technique provides valid estimates of alveolar pressure and airway resistance continuously throughout both phases of the respiratory cycle over a wide range of volumes and flow rates. It may prove to be useful in the assessment of effort and airway obstruction in patients with a variety of pulmonary conditions.

Adult↗
PubMed1984

Pulmonary function in adolescents with mild idiopathic scoliosis.

Spirometric indices, lung volumes, maximum voluntary ventilation, and maximum inspiratory and expiratory pressures were measured in 44 adolescents with mild idiopathic scoliosis (spinal curvature less than 30 degrees). All were symptom free, but six (13.6%) showed a restrictive defect with forced vital capacity less than 80% of predicted. In 12 subjects (27.3%) maximum voluntary ventilation was reduced to less than 80% of predicted normal. Forced vital capacity was significantly correlated with maximum inspiratory pressure and with maximum expiratory pressure, measures of respiratory muscle strength, but was not related to the degree of thoracic curvature. When maximum inspiratory pressure and forced vital capacity were corrected for differences in body size these variables remained positively correlated, most significantly in the girls. These data indicate that ventilatory function may be impaired in mild, idiopathic scoliosis and that the force developed by the respiratory muscles is a more important determinant of this impairment than the radiologically determined degree of spinal curvature.

Adolescent↗
PubMedDate not supplied

Within- and between- subject variability of indices from the closing volume and flow volume traces.

The within-subject variability of consecutive measurements of indices derived from the closing volume (CV) trace and from the maximal expiratory flow volume (MEFV) curve was studied in 24 subjects. The variability of the closing volume and of the maximal expiratory flow rates at 50 percent (Vmax. 50) and 75 percent (Vmax. 75) of the expired vital capacity was about three to eight times greater than that of the FEV1, FVC or FEV1 percent. The lung volume measured from total lung capacity to the onset of airway closure (OAC) was about five times more reproducible than the CV. The coefficients of variation for the CV (as a percentage of the vital capacity), the Vmax. 75, and the OAC, both in litres and as a percentage of the vital capacity, were significantly correlated with age. No difference in the mean coefficients of variation for the CV, OAC, Vmax. 50 or Vmax. 75 were found with respect to sex, smoking habit or previous experience with the test routines. The between-subject variability of the FEV1, FVC, FEV1 percent, transfer factor, diffusion coefficient, Vmax. 50, Vmax. 75, CV and OAC was evaluated from a study of 75 asymptomatic lifetime non-smokers. The variability of the Vmax. 50, Vmax. 75 and CV was about two to eight times greater than that of the other tests used, irrespective of sex. The OAC (percent VC) was three to four times less variable than the CV. The variability of the Vmax. 50 and Vmax. 75 was reduced by, on average, 7 percent when these flow rates were expressed per litre of FVC.

Adult↗
PubMed1985

The bronchodilator effect and pharmacokinetics of theobromine in young patients with asthma.

The bronchodilator effect of a 10 mg/kg dose of theobromine (3,7-dimethylxanthine) was compared with that of 5 mg/kg of theophylline (1,3-dimethylxanthine) in young patients with asthma. Bronchodilation, as assessed by forced vital capacity, forced expiratory volume in the first second, forced expiratory flows at 25%, 50%, and 75% of vital capacity, and percent of forced expiratory volume in the first second/forced vital capacity did not differ significantly between the two drugs. After each drug bronchodilation peaked at 2 hours and lasted for 6 hours, although it was not always statistically significant for theobromine. The mean peak serum concentrations of both drugs, the time at which peak serum concentrations occurred, and elimination half-life values were similar for theobromine and theophylline.

Adolescent↗
PubMed1982

Parenteral vs. inhaled atropine: density dependence of maximal expiratory flow.

Using forced vital capacity maneuvers, we measured maximal expiratory flow rates (Vmax) and static elastic recoil pressures of the lung [Pst(L)] using quasi-static maneuvers in normal nonsmoking human subjects who were breathing air and after a washing of 80% helium-20% oxygen before and after both inhaled and intravenously administered atropine sulfate. By both routes there were equivalent increases in Vmaxair but different effects on density dependence (DD) of Vmax (DD = ratio of VmaxHeO2 to Vmaxair) and on Pst(L). At 30% of vital capacity, DD decreased from an average of 1.47 to 1.32 (P less than 0.01, paired t test) after inhaled drug and did not change after parenteral administration [1.44 vs. 1.48 (P greater than 0.2)]. After inhalation Pst(L) did not change, but after parenteral administration Pst(L) significantly decreased. We interpret these findings to indicate a predominantly large-airway effect with the inhalation route and a more uniform dilatation after the parenteral dose. These results contrast with beta-adrenergic dilatation following which small-airway effects predominate regardless of route of administration.

Adult↗
PubMed1994

Respiratory health status in swine producers relates to endotoxin exposure in the presence of low dust levels.

We conducted an assessment of respiratory health status including questionnaire and spirographic measurements in 54 male swine producers age 36.3 +/- 11.1 years (mean +/- SD) who worked an average of 10.7 +/- 6.3 years in the industry and spent 4.7 +/- 2.1 hours per day in the swine barns, and we also measured atmospheric contaminants including carbon dioxide, ammonia, total dust, respirable dust, and airborne endotoxin. Mean atmospheric dust contaminant levels were as follows: carbon dioxide, 2632 +/- 807 ppm; ammonia, 11.3 +/- 4.2 ppm; total dust, 2.93 +/- 0.92 mg/m3; respirable dust, 0.13 +/- 0.05 mg/m3; and endotoxin, 11,332 +/- 13,492 endotoxin units/m3. Of these, endotoxin related to forced vital capacity (P < .05) and endotoxin x hours per day was related to forced vital capacity (P < .05) and to forced expiratory volume in 1 second (P = .06). Respiratory symptoms and lung function studies did not relate to categories of low, medium, and high exposure to respirable dust. However, categories of endotoxin (available on 46 workers) related to respiratory symptoms (cough, P = .02; chronic bronchitis, P = .06; and to forced vital capacity, P < .01). These data suggest that respiratory health status relates to endotoxin levels but not to dust level exposures in the presence of low dust levels and indicates that control measures should include endotoxin as well as dust control.

Adult↗
PubMed2003

Smoking and obstructive lung dysfunction in persons with chronic spinal cord injury.

BACKGROUND: Persons with higher-level spinal cord injury (SCI) have reduced vital capacity and increased risk of respiratory symptoms and illness, with smokers experiencing excess vital capacity losses. To date, obstructive lung dysfunction, the most prominent effect of smoking in the able-bodied population, has not been characterized in persons with SCI. OBJECTIVE: To determine whether smokers and/or nonsmokers with SCI are at increased risk to develop obstructive lung dysfunction, as measured by the ratio of forced expired volume in 1 second to forced vital capacity (FEV1/FVC). METHODS: Regression analyses on cross-sectional data from routine clinical testing of outpatients followed at the Bronx Veterans Affairs Medical Center in metropolitan New York (NY) and Rancho Los Amigos National Rehabilitation Center in metropolitan Los Angeles (LA) tested the relationship of FEV1/FVC (percentage of predicted normal value) to age, SCI characteristics, and smoking status. RESULTS: NY current smokers showed a significant (P < 0.01) excess decline in FEV1/FVC with increasing age; 35% fell below normal limits compared with 16% of NY former and never smokers. LA current smokers, who were generally younger and smoking less, showed a less clear age-related decline. Never smokers in NY or LA showed no age-related decline beyond that expected in the general population. Former smokers resembled never smokers, except that NY paraplegics showed borderline-significant (P = 0.09) excess age-related decline, which was less than that in NY current smokers. CONCLUSION: Smokers with SCI appeared to be at excessive risk for obstructive lung diseases. Smoking cessation appeared to reduce the risk substantially. Careful longitudinal studies are needed to confirm these findings.

Adult↗
PubMed1981

Lung function of office workers exposed to humidifier fever antigen.

Office workers who became sensitised to antigens derived from humidifier sludge developed episodes of fever, malaise, and other symptoms, including polyuria and mild chest tightness. The episodes usually occurred on a Monday evening and were to some extent dose-related. Lung function was assessed over a day shift on two occasions, including one after which almost all the susceptible subjects developed symptoms. The symptoms were preceded by a 6% reduction in forced expiratory volume and vital capacity, a corresponding increase in residual volume, and a reduction in flow rate after 75% vital capacity had been expired. There were no changes in peak expiratory flow, forced expiratory flow at 50% of vital capacity, or transfer factor. In some subjects the transfer factor was apparently reduced 36 hours later, but for this there may have been another explanation. The physiological features were considered to reflect narrowing of small airways in the lung. The changes, however, were minimal and not the main cause of the symptoms. A feature of the episode was the severity of the constitutional symptoms despite the low airborne dust levels.

Adult↗
PubMed1976

Effect of inspired volume on closing volume.

Closing volume (CV) was ?EASURED WITH THE RESIDENT GAS TECHNIQUE IN 12 HEALTHY SEATED SUBJECTS AGE 22-70 YR, AND IN 8 SUBJECTS WITH THE BOLUS TECHNIQUE. Various volumes were inspired (Vi range: 20-100% vital capacity) from residual volume and CV was assessed on the subsequent recording of expired volume versus gas concentration. The results indicate that the resident gas technique may erroneously underestimate CV at reduced Vi in conformity with calculations which predict that during expiration, after a certain reduced VI, the nitrogen concentration is identical in the most basal lung region and at the mouth. CV obtained with the bolus technique decreased linearly with reduced Vi and the effect appeared to be age dependent according to the equation CV50/CV100=0.0078 X age +1.18, where CV50 and CV100 denote the bolus CV corresponding to Vi=50% and 100% of vital capacity. Therefore, in older subjects, during tidal breathing, airways appear to close at substantially lower lung volume than previously considered.

Adult↗
PubMed1990

Comparison of conventional and rapid inhalational induction of anaesthesia with enflurane.

Inhalational induction of anaesthesia using either a conventional method or a vital capacity breath of 4% enflurane in 67% nitrous oxide was compared in 30 adult surgical patients. Induction time was significantly faster in patients who took a vital capacity breath (71, SD 22 versus 132, SD 18 seconds, p less than 0.01). There were no significant differences between groups in respect of systolic blood pressure, heart rate, arterial oxygen saturation or incidences of excitement or coughing. The vital capacity breath method was acceptable to 87% of patients.

Adult↗
PubMed1978

Bronchoscopy with normoventilation. Automatic ventilation with Sanders technique. A clinical investigation.

Forty six patients, who had to be subjected to diagnostic bronchoscopy under general anaesthesia (thiopental, pethidine, O2-N2O, suxamethonium) were ventilated using Wolf's injectomat (automated Sanders principle) in an attempt to find a setting for the apparatus that would provide normoventilation of the patient, independently of the diagnostic procedure. The first 24 patients were ventilated with the apparatus having a fixed setting: the latter being presumed to provide normo- or hyperventilation. This was confirmed and a steady state of PaCO2 was reached after ventilation for 10 min. This PaCO2 was well correlated with the vital capacity of the patients expressed factorially, in relation to the expected normal value. The investigation renders probable the observation that patients with a greatly reduced vital capacity (less than 50% of the normal value) can rarely be ventilated with the apparatus. On the other hand, a reduced FEV1 has little influence on the efficiency of the apparatus. The apparatus was adjusted in agreement with the above mentioned relation to vital capacity for the following 21 patients, in as much as the change in ventilation was carried out by a change in frequency, while the driving pressure of the apparatus and the inspiration time were maintained unchanged. Normoventilation was obtained in these patients independently of the fact that the bronchoscope was constantly open for the insertion of instruments.

Bronchoscopy↗
PubMed1987

Longitudinal changes in lung function and respiratory symptoms in progressive systemic sclerosis. Prospective study.

Most patients with progressive systemic sclerosis (PSS) exhibit lung involvement. However, the natural history of lung disease in PSS remains poorly defined. To evaluate lung function over time in PSS, a battery of lung function tests were prospectively performed serially between 1973 and 1982 in 61 patients with PSS. Functional indexes of restriction (vital capacity and total lung capacity) and diffusion impairment (diffusing capacity) showed greater-than-expected annual rates of change. Male subjects showed a trend toward faster declines in forced vital capacity, forced expired volume in one second, total lung capacity, and functional residual capacity and a more rapid increase in static recoil pressure at 90 percent of total lung capacity than did female subjects. Nonsmokers had greater rates of decline in total lung capacity and static lung compliance (but not in forced vital capacity or diffusing capacity) and a greater rate of increase in static recoil pressure than did current and former smokers. Level of lung function at initial study visit, age, race, and chlorambucil therapy had no significant effect on the annual rates of change in lung function, whereas longer duration of disease prior to study entry was associated with a slower annual decrease in lung volumes. Between the first and last visits (mean interval 3.1 years, maximum nine years), the frequency of abnormality in pulmonary function test results showed significant change only in the diffusing capacity (60 percent increasing to 82 percent) and static lung compliance (40 percent increasing to 54 percent), whereas the frequency of respiratory symptoms showed little change. These findings indicate an overall indolent progression of PSS-related lung disease, with substantial individual variability.

Adult↗
PubMed1976

Small airways in fibrosing alveolitis.

Pulmonary function, including lung elastic recoil, was measured in 9 subjects with fibrosing alveolitis. Closing volume and upstream conductance were studied to assess small airway function. Lung volumes, diffusing capacity, and transfer coefficient were decreased. Peak expiratory flow and the ratio of 1-sec forced expiratory volume to forced vital capacity were normal, whereas total lung resistance was low, suggesting that large airways were not narrowed. Lung elastic recoil was increased, but the changes could be accounted for by the loss of lung volume. Closing volume and closing capacity were increased when expressed as a percentage of vital capacity and total lung capacity, respectively; but again, this could be accounted for by the decrease in lung volume, because the absolute lung volume at which airway closure occurred was normal. Upstream conductance was not reduced. We conclude that there is no evidence of narrowing of functional small airways in ventilated parts of the lung. The mechanical findings are compatible with the patchy involvement seen pathologically in fibrosing alveolitis.

Adult↗
PubMed1964

THE VALUE OF PULMONARY FUNCTION STUDIES IN THE ASSESSMENT OF PATIENTS FOR CARDIAC SURGERY.

Preoperative pulmonary function, intracardiac pressures and degree of dyspnea were related to the incidence of postoperative respiratory insufficiency in 102 adult patients who underwent cardiac surgery. The purpose was to seek a reliable method of prognosticating the risk of postoperative respiratory insufficiency, especially after the use of cardiopulmonary bypass. When the heart-lung pump was used, 24 of 30 patients with a vital capacity less than 80% of the predicted normal developed respiratory insufficiency, whereas only eight of 41 patients with a normal vital capacity had this complication. In 26 patients where the vital capacity and gas diffusion were both normal, only three developed postoperative respiratory insufficiency. Other single or combined pulmonary function abnormalities, including tests of the mechanics of breathing, were of no greater value in predicting the postoperative course. The degree of dyspnea and the level of intracardiac pressures, although sometimes helpful, were often misleading.

Adult↗
PubMed1993

Early pulmonary disease in systemic sclerosis: a comparison between carbon monoxide transfer factor and static lung compliance.

OBJECTIVES: Pulmonary disease is responsible for considerable morbidity and mortality in systemic sclerosis (SSc). Static lung compliance (Cst) has been observed to be decreased more often in SSc than the vital capacity, indicating that it is a sensitive measure of lung restriction. In this study Cst was compared with the carbon monoxide transfer factor (TLCO), a widely used measure of the function of the alveolar capillary unit, and with lung volumes in 59 patients with confirmed or suspected SSc. METHODS: Cst was calculated from the oesophageal pressure at different lung volumes and the TLCO was measured with the single breath method. RESULTS: The TLCO was found to be the earliest sign of pulmonary disease and was already decreased at a disease duration of one year or less. Surprisingly, no relation was found between the TLCO and smoking habits, nor the degree of peripheral vascular disease. The TLCO correlated with the Cst and vital capacity. CONCLUSIONS: An early pulmonary lesion can be identified in patients with SSc with decreased TLCO at a time when no fibrotic changes are manifested.

Acute-Phase Proteins↗
PubMed1992

Effects of posture on flow-volume curves during normocapnia and hypercapnia in patients with obstructive sleep apnoea.

BACKGROUND: A high ratio of forced expiratory to forced inspiratory maximal flow at 50% of vital capacity (FEF50/FIF50) may identify upper airway dysfunction. Since hypercapnia increases the motor activity of airway dilating muscles its effects on the maximum expiratory and inspiratory flow-volume curves (MEIFV) in patients with obstructive sleep apnoea and in normal subjects in different postures was studied. METHODS: The effects of posture on the maximum expiratory and inspiratory flow-volume curves during the breathing of air and 7% carbon dioxide in 11 patients with obstructive sleep apnoea were compared with those in nine normal subjects. Measurements were made in the sitting, supine, and right lateral recumbent positions. Forced expiratory flow at 50% vital capacity (FEF50), forced inspiratory flow at 50% vital capacity (FIF50) and FEF50/FIF50 were determined. RESULTS: In the normal subjects FEF50, FIF50, and FEF50/FIF50 were not affected by change in posture or by breathing carbon dioxide. In the patients there was a fall in FIF50 and an increase in FEF50/FIF50 when breathing air in the supine position compared with values in the seated and lateral position. While they were breathing carbon dioxide there was a slight increase in FEF50 when patients were seated or in the lateral position compared with values during air breathing. Hypercapnia abolished the effects of posture on FEF50/FIF50. Values for FEF50/FIF50 in the supine position while they were breathing air correlated with the apnoeic index but not with other polysomnographic data. CONCLUSION: In patients with obstructive sleep apnoea the upper airway is prone to collapse during inspiration when the patient is supine, even when awake; this tendency can be reversed by breathing carbon dioxide.

Adult↗