Lung Volumes In Subjects Research Articles

Serum insulin is associated with right ventricle function parameters and lung volumes in subjects free of cardiovascular disease.

Diabetes mellitus is an established risk factor for cardiovascular diseases. Even impaired levels of glucose and insulin might harm organ function prior to diabetes onset. Whether serum glucose or insulin plays a direct role in cardiac dysfunction or lung volume reduction remains unclear. The aim was to investigate the relationship between glucose and insulin with the right ventricle and lung volumes within KORA-MRI FF4 study. From the KORA-MRI FF4 cohort study 337 subjects (mean age 55.7 ± 9.1 years; 43% women) underwent a whole-body 3T MRI scan. Cardiac parameters derived from a cine-steady-state free precession sequence using cvi42. MRI-based lung volumes derived semi-automatically using an in-house algorithm. Fasting serum glucose, fasting insulin levels, and HOMA index were calculated in all study subjects. Linear regression analyses were performed to assess the relationships between glucose and insulin levels with right ventricle volumes and lung volumes adjusted for age, sex, BMI, and cardiovascular risk factors. In univariate and multivariate-adjusted models, high serum insulin was inversely associated with end-diastolic volume (β = -12.43, P < 0.001), end-systolic volume (β = -7.12, P < 0.001), stroke volume (β = -5.32, P < 0.001), but not with ejection fraction. The association remained significant after additional adjustment for lung volumes. Similarly, serum insulin was inversely associated with lung volume (β = -0.15, P = 0.04). Sensitivity analysis confirmed results after excluding subjects with known diabetes. Serum insulin was inversely associated with right ventricle function and lung volumes in subjects from the general population free of cardiovascular disease, suggesting that increased insulin levels may contribute to subclinical cardiopulmonary circulation impairment.

The influence of an electrical impedance tomography belt on lung function determined by spirometry in sitting position

Objective: The aim of the study was to examine whether an electrical impedance tomography (EIT) electrode belt changed the lung function in healthy volunteers and patients with respiratory muscle weakness (RMW) and chronic obstructive pulmonary disease (COPD). Approach: In total, thirty subjects were included (10 healthy volunteers, 10 subjects with RMW, maximum inspiratory pressure < 40 cmH2O, and 10 COPD, grade I–IV). Spirometry measurements were conducted in a sitting position once a day at similar times on two consecutive days. Slow expiratory vital capacity (VC), forced vital capacity (FVC) and maximum voluntary ventilation (MVV) manoeuvres were performed. On day 1, spirometry was performed without the EIT electrode belt, and on day 2, the belt was attached to the thorax. Main results: Lung function was not influenced by the electrode belt in healthy subjects. The test-retest reliability in the healthy group was 0.89, 0.89 and 0.85 for VC, FVC and MVV, respectively. On the other hand, all investigated parameters were significantly decreased in the RMW group (VC, 51.3 ± 18.0 versus 46.5 ± 18.0% predicted, without versus with EIT belt, p< 0.01; FVC, 51.7 ± 19.0 versus 45.8 ± 18.1% predicted, p< 0.01; MVV, 41.0 ± 20.0 versus 38.8 ± 19.6% predicted, p< 0.01). VC and MVV also decreased significantly in the COPD group (VC, 77.4 ± 20.5 versus 74.6 ± 18.8% predicted, p< 0.05; MVV, 57.4 ± 15.7 versus 54.4 ± 12.5% predicted, p< 0.05). Significance: An EIT electrode belt could reduce lung volumes in subjects with pre-existing lung diseases. Comparing lung function acquired with an electrode belt to corresponding values obtained without the belt should be avoided.

Early onset of airway derecruitment assessed using the forced oscillation technique in subjects with asthma.

Derecruitment of air spaces in the lung occurs when airways close during exhalation and is related to ventilation heterogeneity and symptoms in asthma. The forced oscillation technique has been used to identify surrogate measures of airway closure via the reactance (Xrs) versus lung volume relationship. This study used a new algorithm to identify derecruitment from the Xrs versus lung volume relationship from a slow vital capacity maneuver. We aimed to compare two derecruitment markers on the Xrs versus volume curve, the onset reduction of Xrs (DR1vol) and the onset of more rapid reduction of Xrs (DR2vol), between control and asthmatic subjects. We hypothesized that the onset of DR1vol and DR2vol occurred at higher lung volume in asthmatic subjects. DR1vol and DR2vol were measured in 18 subjects with asthma and 18 healthy controls, and their relationships with age and height were examined using linear regression. In the control group, DR1vol and DR2vol increased with age (r2 = 0.68, P < 0.001 and r2 = 0.71, P < 0.001, respectively). DR1vol and DR2vol in subjects with asthma [76.58% of total lung capacity (TLC) and 56.79%TLC, respectively] were at higher lung volume compared with control subjects (46.1 and 37.69%TLC, respectively) (P < 0.001). DR2vol correlated with predicted values of closing capacity (r = 0.94, P < 0.001). This study demonstrates that derecruitment occurs at two points along the Xrs-volume relationship. Both derecruitment points occurred at significantly higher lung volumes in subjects with asthma compared with healthy control subjects. This technique offers a novel way to measure the effects of changes in airways/lung mechanics. NEW & NOTEWORTHY This study demonstrates that the forced oscillation technique can be used to identify two lung volume points where lung derecruitment occurs: 1) where derecruitment is initiated and 2) where onset of rapid derecruitment commences. Measurements of derecruitment increase with age. The onset of rapid derecruitment was highly correlated with predicted closing capacity. Also, the initiation and rate of derecruitment are significantly altered in subjects with asthma.

Healthy Lung Vessel Morphology Derived From Thoracic Computed Tomography.

Knowledge of the lung vessel morphology in healthy subjects is necessary to improve our understanding about the functional network of the lung and to recognize pathologic deviations beyond the normal inter-subject variation. Established values of normal lung morphology have been derived from necropsy material of only very few subjects. In order to determine morphologic readouts from a large number of healthy subjects, computed tomography pulmonary angiography (CTPA) datasets, negative for pulmonary embolism, and other thoracic pathologies, were analyzed using a fully-automatic, in-house developed artery/vein separation algorithm. The number, volume, and tortuosity of the vessels in a diameter range between 2 and 10 mm were determined. Visual inspection of all datasets was used to exclude subjects with poor image quality or inadequate artery/vein separation from the analysis. Validation of the algorithm was performed manually by a radiologist on randomly selected subjects. In 123 subjects (men/women: 55/68), aged 59 ± 17 years, the median overlap between visual inspection and fully-automatic segmentation was 94.6% (69.2–99.9%). The median number of vessel segments in the ranges of 8–10, 6–8, 4–6, and 2–4 mm diameter was 9, 34, 134, and 797, respectively. Number of vessel segments divided by the subject's lung volume was 206 vessels/L with arteries and veins contributing almost equally. In women this vessel density was about 15% higher than in men. Median arterial and venous volumes were 1.52 and 1.54% of the lung volume, respectively. Tortuosity was best described with the sum-of-angles metric and was 142.1 rad/m (138.3–144.5 rad/m). In conclusion, our fully-automatic artery/vein separation algorithm provided reliable measures of pulmonary arteries and veins with respect to age and gender. There was a large variation between subjects in all readouts. No relevant dependence on age, gender, or vessel type was observed. These data may provide reference values for morphometric analysis of lung vessels.

Methods for Measuring Lung Volumes: Is There a Better One?

Background: Accurate measurement of lung volumes is of paramount importance to establish the presence of ventilatory defects and give insights for diagnostic and/or therapeutic purposes. Objectives: It was the aim of this study to measure lung volumes in subjects with respiratory disorders and in normal controls by 3 different techniques (plethysmographic, dilutional and radiographic methods), in an attempt to clarify the role of each of them in performing such a task, without any presumptive ‘a priori' superiority of one method above others. Patients andMethods: In different groups of subjects with obstructive and restrictive ventilatory defects and in a normal control group, total lung capacity, functional residual capacity (FRC) and residual volume were measured by body plethysmography, multi-breath helium (He) dilution and radiographic CT scan method with spirometric gating. Results: The 3 methods gave comparable results in normal subjects and in patients with a restrictive defect. In patients with an obstructive defect, CT scan and plethysmography showed similar lung volumes, while on average significantly lower lung volumes were obtained with the He dilution technique. Taking into account that the He dilution technique does primarily measure FRC during tidal breathing, our data suggest that in some patients with an obstructive defect, a number of small airways can be functionally closed at end-expiratory lung volume, preventing He to reach the lung regions subserved by these airways. Conclusion: In all circumstances, both CT scan with spirometric gating and plethysmographic methods provide similar values of lung volumes. In contrast, the He dilution method can measure lower lung volumes in some patients with chronic airflow obstruction.

Effect of Acu-TENS on post-exercise expiratory lung volume in subjects with asthma—A randomized controlled trial

This study examined the effect of transcutaneous electrical nerve stimulation applied over acupoints (Acu-TENS) on forced expiratory volume, in patients with asthma, after exercise. Thirty subjects were randomly assigned to three groups. Group 1 received Acu-TENS over acupuncture points Lieque and Dingchuan for 45 min prior to a symptom-limited treadmill exercise test. Group 2 had Acu-TENS similarly applied prior to and throughout the exercise test. Group 3 mimicked Group 1 but without any electrical output from the device. Forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) were recorded before, immediately after and at 20-min intervals post-exercise for 1h. Immediately after exercise, FEV(1) and FVC rose in Group 2 (p=0.015), but decreased in Group 1 and more so in Group 3. The differences became even more marked at 20, 40 and 60 min. Adjunctive Acu-TENS therapy appears to reduce decline of FEV(1) following exercise training in patients with asthma.

Reliability and validity of the lung volume measurement made by the BOD POD body composition system

The BOD POD Body Composition System uses air-displacement plethysmography to measure body volume. To correct the body volume measurement for the subject's lung volume, the BOD POD utilizes pulmonary plethysmography to measure functional residual capacity (FRC) at mid-exhalation as that is the subject's lung volume during the body volume measurement. Normally, FRC is measured at end-exhalation. The BOD POD FRC measurement can be corrected to an end-exhalation volume by subtracting approximately one-half of the measured tidal volume. Our purpose was to determine the reliability and validity of the BOD POD FRC measurement at end-exhalation. Ninety-two healthy adults (half female) underwent duplicate FRC measurements by the BOD POD and one FRC measurement by a traditional gas dilution technique. The latter method was used as the reference method for the validity component of the study. The order of the FRC measurements by the two methods was randomized. The test-retest correlation coefficients for the duplicate BOD POD FRC measurements for the male and female subjects were 0.966 and 0.948, respectively. The mean differences between the BOD POD FRC trial #1 measurement and gas dilution FRC measurement for the male and female subjects were -32 and -23 ml, respectively. Neither difference was statistically significant. The correlation coefficients for these two measurements in the male and female subjects were 0.925 and 0.917, respectively. Based on these results, we conclude that the BOD POD FRC measurement in healthy males and females is both reliable and valid.

Arm positioning alters lung volumes in subjects with COPD and healthy subjects

Subjects with chronic obstructive pulmonary disease (COPD) have difficulty performing arm exercise, particularly if the arms are unsupported and elevated. The purpose of this study was to evaluate the effect of arm position on static lung volumes in COPD and healthy subjects. Lung volumes were measured by plethysmography in nine COPD subjects (mean age +/- SD = 67.3 +/- 10.3 years; % pred FEV1 +/- SD = 39.7 +/- 10.9%) and nine healthy subjects (mean age +/- SD = 55.8 +/- 8.8 years; % pred FEV1 +/- SD = 102.9 +/- 12.2%) with the arms below 90 degrees shoulder flexion, at 90 degrees shoulder flexion and above 90 degrees shoulder flexion. In all subjects a significant increase in functional residual capacity (FRC) and reduction in inspiratory capacity (IC) was shown with arms above 90 degrees shoulder flexion when compared with both arms below 90 degrees shoulder flexion (mean increase in FRC (95% CI) was 0.17 L (0.06 to 0.27) for COPD and 0.29 L (0.11 to 0.47) for healthy subjects; mean reduction in IC (95% CI) was 0.24 L (0.1 to 0.38) for COPD and 0.45 L (0.22 to 0.68) for healthy subjects) and arms at 90 degrees shoulder flexion (mean increase in FRC (95% CI) was 0.15 L (0.01 to 0.29) for COPD and 0.22 L (0.11 to 0.34) for healthy subjects; mean reduction in IC (95% CI) was 0.14 L (0.01 to 0.26) for COPD and was 0.29 L (0.17 to 0.42) for healthy subjects). These changes may alter lung mechanics and, in COPD subjects, may affect their ability to perform arm exercise above shoulder height

Variability in airway conductance and lung volume in subjects with asthma

Variability in airway conductance (Gaw) and lung volume (TGV) was studied in 26 subjects with moderately severe asthma during a 9-week period. Specific airway conductance (SGaw) was calculated as Gaw:TGV. There was considerable inter-individual variability in airway conductance, and a smaller variability in TGV. Airway conductance (SGaw) showed an eight-fold difference and TGV a three-fold difference between smallest and largest values. The intra-individual variability was less, with a range of +/- 55% (SGaw) and +/- 12% (TGV) of the grand mean, respectively. The error of the method contributed only marginally to the variations in airway conductance. These data for spontaneous variability of conductance facilitate, for example, the assessment of the clinical importance of changes in lung function seen after exposure to air pollutants in chamber studies. Furthermore, the substantial inter-individual variability in conductance argues against comparing samples of asthmatic subjects in polluted and non-polluted areas, and in favour of prospective studies of cohorts of subjects with asthma.

Bronchoconstrictor and antibronchoconstrictor properties of inhaled prostacyclin in asthma.

Prostacyclin (PGI2) is generated in appreciable amounts during allergic reactions in human lung tissue. To define its activity on human airways we have studied the effects of doubling concentrations of inhaled PGI2 and its hydrolysis product 6-oxoprostaglandin F1 alpha (6-oxo-PGF1 alpha) on specific airway conductance (sGaw), maximum expiratory flow at 30% vital capacity (Vmax30), forced expiratory volume in 1 s (FEV1), and static lung volumes in subjects with mild allergic asthma. In a second study the effect of inhaled PGI2 on bronchoconstriction provoked by increasing concentrations of inhaled prostaglandin (PG) D2 and methacholine was observed. Inhalation of PGI2 up to a concentration of 500 micrograms/ml had no significant effect on sGaw but produced a concentration-related decrease in FEV1 and Vmax30 in all subjects. In two of four subjects inhalation of PGI2 also increased residual volume and decreased vital capacity but had no effect on total lung capacity. PGI2, but not 6-oxo-PGF1 alpha, protected against bronchoconstriction provoked by either PGD2 or methacholine whether airway caliber was measured as sGaw, FEV1, or Vmax30. The apparent disparity between the bronchoconstrictor and antibronchoconstrictor effects of PGI2 might be explained by its potent vasodilator effect in causing airway narrowing through mucosal engorgement and reducing the spasmogenic effects of other inhaled mediators by increasing their clearance from the airways.

Cardiogenic oscillations in expired gas: origin and mechanism

I produced cardiogenic oscillations (C.O.) of gas concentration for Ar, N 2 and CO 2 in the expirate by inspiration from RV of a bolus of ArO 2 mixture followed by O 2 to TLC. In 3 out of 4 subjects, C.O. of Ar changes phase during expiration by a half cycle with respect to C.O. of CO 2 as was predicted by a previously suggested model (Arieli, R., A.J. Olszowka and H.D. Van Liew (1981) J. Appl. Physiol. 51: 922–928). The model attributed the production of C.O. to fluctuation of the relative flow from two units differ from each other in their compliance; and due to an assumed dependence of the resistance on the compliance, the time constant of each lung unit changes as a function of lung volume. By scaling the subject's lung volume to Weibel Model A and by the use of expired volume and ECG, I suggest that the origin of C.O. seen at the mouth is at the terminal bronchioles. I made use of the arrhythmic heart rate of one subject to confirm the aligning of ECG with C.O. and also to show that the volume between the site of C.O. origin and the mouth is function of lung volume. The differences between C.O. of Ar, N 2 and CO 2 are attributed to their distribution pattern in the lung.

Voluntary reaction times for phonation initiation

Simple neuromechanical reaction times for voluntary initiation of phonation were investigated in 15 males and 15 females as a function of (1) stimulus type: either a 1‐kHz tone or a drop from 6 cm H2O in intraoral air pressure to atmospheric pressure; (2) abducted, adducted, or uncontrolled prephonatory vocal‐fold position and (3) 75%, 50%, and 25%, of subject's lung volume. Auditory‐manual responses were also obtained from these same subjects. All responses were to stimulus onset. The fastest neuromechanical reaction times were 120 msec; however, the average time for phonation initiation across subjects was 180 msec. Auditory‐vocal reaction times were generally faster than somesthetic‐vocal reaction times, but these differences were not significant. Faster auditory‐vocal reaction times were obtained at mid than at lung volume extremes, as well as when phonation was initiated from abducted rather than adducted prephonatory vocal‐fold positions. Manual reaction times were significantly faster than vocal reaction times.

The relationship between airway resistance, airway conductance and lung volume in subjects of different age and body size.

The relationship between airway resistance, airway conductance and lung volume in subjects of different age and body size.