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PubMed1976

Closing volume in coal miners.

Closing volume and closing capacity were determined in 82 working Appalachian coal miners and in a comparable group of control subjects. Abnormalities of closing volume and closing capacity were related to other measurements of pulmonary function. The relationship of smoking history, dust exposure, and presence of pneumoconiosis and bronchitis to elevations of closing volume and closing capacity was determined. It was shown that nonsmoking miners had elevated closing volume and closing capacity when compared to control subjects. Miners who were smokers or ex-smokers also had elevated closing capacity when compared to control subjects. Neither bronchitic symptoms nor the radiographic presence of pneumoconiosis were associated with an elevation of closing volume or closing capacity.

Bronchitis↗
PubMed1976

Epidemiological limitations of the nitrogen closing volume test.

Closing volume was measured in 216 men aged 46-68 years. They were divided in 5 age groups and classified as either symptomatic or asymptomatic according to answer to standardized interviews. In 3 of 5 age groups mean value for closing volume percent (CV%) for symptomatic persons was lower than the mean value for asymptomatic persons. CV% is not considered useful as the dependent variable in a multiple regression analysis. In all 5 age groups the mean value of slope of alveolar plateau was higher for symptomatic than for asymptomatic persons. Slope af alveolar plateau is considered useful as dependent variable in a multiple regression analysis. One of the reasons for the false negative CV%-values is believed to be influence of increased uneven and sequential ventilation of the lungs, expressed in the slope of alveolar plateau.

Aged↗
PubMed1977

Difference between the He bolus and N2 technique for measuring closing volume.

We measured closing volume in sixteen healthy subjects simultaneously and separately with a bolus of He (using a rapid catharaometer) and with the N2 technique. In another group of 35 active workers (some with airway obstruction), closing volume was measured separately with those two methods. In both groups the He closing volume was significantly higher than the N2 closing volume. We attribute this difference to a less marked vertical N2 concentration gradient, leading to a less clearly defined separation between phase III and IV and resulting in an underestimation of the N2 closing volume. Indeed, increasing the N2 gradient in the lung, by inspiring O2 from a higher than residual volume level, increased the N2 closing volume which became comparable to the He closing volume. We also found, for both He and N2 tracings, a significant between-observers difference in reading of the closing volume. However, the difference in reading of ts difference in reading of the closing volume. However, the difference was less important for He closing volumes. We conclude that the bolus method improves the resolution of closing volume and decreases the interobserver variability.

Adult↗
PubMed1978

Effect of the slope of the alveolar plateau on determination of closing volume.

Repeated closing volume (CV) determinations were obtained simultaneously with the nitrogen method (CV-N2) and with a helium bolus method (CV-He) in 19 selected subjects with normal routine spirometry. Ten subjects had normal slopes of phase III and nine had abnormally steep slopes of phase III obtained with the nitrogen method. No systematic difference was found between CV-N2 and CV-He irrespective of the steepness of phase III, which seems to indicate that at least in spirometrically normal subjects airway closure is adequately assessed by the nitrogen method - even in the presence of a steep slope of phase III.

Closing Volume↗
PubMed1980

Effects of preinspiratory volume on the nitrogen closing volume test.

The effect of varying the preinspiratory volume (VIair; range: 0-75% vital capacity, VC) on the nitrogen closing volume (CV) test was studied in twelve seated subjects, aged 24-62 years. When VIair was increased from 0 to about 12% VC, the height of phase IV, the amplitude of the cardiogenic oscillations, CV and the slope of phase III increased. The height of phase IV and the amplitude of the cardiogenic oscillations showed a maximum at VIair = 12% VC, although the average CV was about 18% VC. While the height of phase IV and the amplitude of the cardiogenic oscillations decreased when VIair was increased above 12% VC, CV did not change and the slope of phase III increased consistently. These results cannot be explained solely by the regional lung volume model of Sutherland et al. (1968). However, if that model is extended to include the assumption that within a region alveoli behind closed airways may be differently expanded, we predict CV to be underestimated at low VIair, independently of the upper to lower nitrogen concentration difference, in agreement with present findings. This assumption would also explain why the maximal height of phase IV can be obtained at a VIair lower than CV.

Adult↗
PubMed1979

Airway closure and closing volume.

Using boluses of radioactive Xe we compared regional N2O uptake with regional perfusion distribution during open glottis breath hold in five seated men. Measurements were made near residual volume, at closing volume (CV), above CV and when possible, between CV and residual volume (RV). At low lung volumes basal N2O uptake was small whereas basal blood flow was not. This discrepancy was interpreted as evidence of airway closure and was quantitated. All subjects showed extensive basal closure near RV. At closing volume four of five subjects demonstrated closure and some closure was evident in these subjects at volumes in excess of CV. The increase in airway closure with decreasing lung volume was much greater below CV than above it. Conventional CV tracings were obtained using helium boluses; the height of phase IV was positively correlated with the change in airway closure between CV and RV as assessed by the N2O technique. The slope of phase III did not correlate with the amount of airway closure measured at CV. We concluded that the conventionally measured CV is not the volume at which airway closure begins but that the onset of phase IV reflects an increase in basal airway closure and the height of phase IV reflects the amount of basal closure between CV and RV.

Adult↗
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↗
PubMed1977

Ability of spirometry, flow-volume curves and the nitrogen closing volume test to detect smokers. A population study.

Vital capacity, FEV1 and various measurements of forced expiratory flows as well as closing volume (CV), closing capacity (CC), the mean slope of the alveolar plateau (phase III), the maximal amplitude of the cardiogenic oscillations (N2-osc), and other variables obtained from the nitrogen CV-test were measured in random samples of 50- (n = 221) and 60-year-old (n - 410) men in Gothenburg. All the variables were significantly different in smokers consuming 15 g or more tobacco daily compared with asymptomatic non-smokers. Reference values were established from measurements in the non-smokers without respiratory symptoms, and the sensitivities of the measured variables to tobacco smoking were assessed. Phase III revealed the highest sensitivity, being abnormal in about 40-60 % of subjects smoking 15 g or more tobacco daily and in about 30-35 % of subjects smoking less. CV and FEV1 were approximately equally sensitive, being abnormal in about 10-30 % of subjects smoking 15 g or more daily and in about 5-20 % in subjects smoking less. Other measurements of maximal expiratory flow rates gave values below minus two standard deviations for the appropriate reference group in less than 15 % of the smokers. However, when we took the skewed distribution of reference values into account we found a two- to sixfold increase of the sensitivities of these variables in the 50-year-old smokers, in which abnormal values were obtained in about 30-40 % of subjects smoking 15 g or more daily and in about 10-15 % in subjects smoking less. Taking all variables obtained from the CV-test in conjunction, one or more abnormal valves were obtained in 60-70 % of the subjects smoking 15 g or more daily. To the extent that sensitivity to smoking reflects sensitivity to abnormalities in small airways, phase III appeared to be the most efficient single measurement for detection of this condition in the present age groups.

Cough↗
PubMed1978

Closing volume and flow volume abnormalities in alpha(1)-antitrypsin phenotype groups in a community population.

Alpha1-antitrypsin phenotype groups, found in a community population studied in Tucson, were compared by using the maximum expiratory flow volume curve and the single-breath nitrogen test, alone and in combination. Subjects 25 to 54 years of age were used for the comparison, among whom there were 728 Pi M, 29 Pi MZ, and 62 Pi MS phenotypes. None of the flow volume parameters or closing volume parameters was able to differentiate among the phenotype groups; subjects in groups heterozygous for alpha1-antitrypsin did not differ from individuals homozygous for Pi M with regard to any or all flow volume or closing volume parameters.

Adult↗
PubMed1981

Closing volume in normal pregnancy.

Closing volume and other principal lung volumes were measured during and after pregnancy in 10 healthy non-smoking women aged 18--25 yr. There were no significant changes on closing volume or closing capacity. A decrease in functional residual capacity as pregnancy progressed resulted in airway closure during tidal breathing in more than 50% of subjects at term when in a supine position, but this did not occur when they were seated.

Adolescent↗
PubMedDate not supplied

Measurement of closing volume in apneic subjects.

Closing volume measurement was adapted for application in apneic intubated, artifically ventilated subjects. A bolus of nitrogen was used as the marker gas. Inspiration and exhalation at a slow, uniform rate between residual volume and total lung capacity was provided by a 7000-ml syringe. Closing volumes in seven anesthetized subjects were similar to those reported for supine, conscious individuals by previous investigators. This adaptation of closing volume measurement should be useful in studying pulmonary dysfunction during anesthesia and during artificial ventilation of patients in respiratory failure.

Adult↗
PubMed1983

[Effect of water immersion as a model of weightlessness on lung closing volume].

The effect of 7-day water immersion combined at night with head-down (6 degrees) tilting on the volumes of lung expiratory closing was examined in 6 healthy male test subjects, aged 25-35. During immersion they showed, along with a stable reduction of the lung vital and functional residual capacity (by 4.2 and 14.8%, respectively), an increase in the fraction parameters of the expiratory closing volumes. The increase in the closing volume (up to 40%) (P less than 0.05) was particularly distinct on immersion day 2. Subsequent changes indicated gradual recovery of the closing volumes and a decline in regional nonuniformity of lung ventilation. The time-course variations in the closing volumes may be attributed to an increase in the intrapulmonary blood volume at the early stage of adaptation to immersion and to a decrease in the nonuniformity of the ventilation-perfusion ratios.

Adult↗