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PubMed1985

Changes in lung volume and deflation stability in hyaline membrane disease.

Total lung capacity (TLC), inspiratory capacity, functional residual capacity, and deflation stability of prematurely delivered Macaca nemestrina primates were measured serially during development of, and recovery from, hyaline membrane disease (HMD) to relate changes in lung volumes to changes in deflation stability. Gestational age-matched primates that did not develop HMD served as controls. TLC, measured by N2 washout, fell at 2-12 h of age (P less than 0.0001) in animals with HMD and remained lower than controls for at least 48 h (P less than 0.005). However, deflation stability, defined as the fraction of TLC remaining upon deflation to 10 cm H2O, improved from 2 to 12 h of age (P less than 0.001). Postmortem studies confirm the measurements of TLC and deflation stability and provide evidence that interstitial thickening and obstruction of air spaces with debris may be partially responsible for the observed changes in TLC in primates that develop HMD. It has been assumed that TLC is reduced in HMD because of atelectasis from elevated alveolar surface tension, but the sequential measurements in these animals suggest that other mechanisms also contribute.

Animals↗

PubMed1999

Static lung volumes: reference values from a Latin population of Spanish descent.

BACKGROUND AND OBJECTIVES: The aim of this study was to develop a set of prediction equations and 90% confidence intervals for static lung volumes using the multibreath helium equilibration method from a sample of asymptomatic Caucasian subjects of Spanish descent. Moreover, these equations were compared with those of previous studies. METHODS: Measurements of static lung volumes using techniques recommended by the American Thoracic Society and the European Community for Steel and Coal were carried out on a selected sample of 591 healthy nonsmoking volunteers (305 men and 286 women) aged 18-88 years, living in the metropolitan area of Valencia, on the east coast of Spain. Multiple regression analysis using height, age and weight as independent variables were used to provide predicted values for both sexes. These reference values were compared with other sets of prediction equations reported in the literature using an independent sample of 69 subjects (32 men and 37 women). RESULTS: Simple linear regression equations using age, height and body weight predicted all the subdivisions of lung volumes (vital capacity, expiratory reserve volume (ERV), inspiratory capacity, functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), FRC/TLC and RV/TLC) as well as more complex equational models. The distribution of residuals fulfilled the assumptions of multiple regression analysis (independence, homoscedasticity and Gaussian distribution of residuals), except for ERV, using simple linear models. The derived equations did not differ significantly from most of the previously reported equations and were usually superior in their ability to predict the lung volumes. CONCLUSIONS: The use of the present prediction equations is recommended in the Latin population of Spanish descent and in populations with similar Caucasian characteristics.

Adolescent↗

PubMed1983

Changes in inert gas rebreathing parameters after ozone exposure in dogs.

The acute (30 min postexposure) and delayed (24 and 48 h postexposure) effects of a 4-h exposure to 1.0 ppm O3 (n = 10), 0.3 ppm O3 (n = 9) were evaluated using an inert multiple gas rebreathing method as well as arterial blood gas determinations in anesthetized dogs. Rebreathing parameters included pulmonary capillary blood flow (Qc), diffusing capacity, functional residual capacity, pulmonary tissue plus capillary blood volume (VTPC), and oxygen consumption. The Qc and PaO2 were significantly decreased 30 min after exposure to O3 and remained decreased 24 and 48 h after exposure only in the 1.0 ppm O3 group. After exposure to 1.0 ppm O3 only, a 33% increase in VTPC was found at 24 but not at 48 h and was confirmed by autopsy lung water determinations. No changes in rebreathing parameters or arterial blood gas measurements occurred in the air exposure control group. Therefore, an acute exposure to O3 resulted in adverse cardiopulmonary effects in dogs. Five additional dogs were exposed to 1.0 ppm O3 for 4 h while breathing spontaneously rather than with ventilation being assisted by electrophrenic stimulation (as done in the other exposures), and no changes in VTPC occurred. Thus, the ventilatory pattern used during O3 exposure is also an important factor in causing critical degrees of parenchymal lung injury.

Animals↗

PubMed1988

Are reduced lung volumes in IDDM due to defect in connective tissue?

Lung volumes were measured by spirometry and helium-dilution technique in 28 young adult men with insulin-dependent diabetes mellitus (IDDM) of long duration and compared with 16 age- and height-matched adult men without diabetes. Reduced values for forced expiratory volume at 1 s, vital capacity, functional residual capacity, total lung capacity, residual volume, and single-breath carbon monoxide transfer factor were found for the IDDM patients compared to the control subjects. The results are consistent with reduced lung volumes in IDDM patients and did not correlate with the presence or absence of mild cheiroarthropathy but may relate to duration of diabetes.

Adult↗

PubMed1986

Cardiac output by impedance cardiography during head-out water immersion.

This study was undertaken to ascertain the suitability of impedance cardiography for qualifying cardiac output during water immersion where the electrodes were wet. The cardiac output was compared during wet and dry immersion with the head above water by breath holding briefly at 3 lung volumes. For dry immersion, the subjects were protected from contacting water during immersion by enveloping the whole body in a thin plastic bag. For wet immersion, the subject went into the water wearing only trunks. Eleven healthy males served as subjects. Both basal thoracic impedance and the minimum rate of impedance change decreased during wet immersion. These changes were specific, which insignificantly influenced the computation of stroke volume as compared to dry immersion. Our results showed no statistical differences between wet and dry immersions, and between measurements made at total lung capacity functional residual capacity, or residual volume. It is concluded that impedance cardiography is applicable directly in wet conditions without having to protect the subject from getting wet.

Adult↗

PubMed1984

Effects of ipratropium bromide and fenoterol aerosols on exercise tolerance.

Twelve male patients with radiological evidence of pulmonary emphysema performed progressive exercise tests on a cycle ergometer. Ipratropium bromide (Ip) 40 micrograms, Fenoterol (Fen) 400 micrograms, their combination (Ip/Fen) and Placebo were administered from metered-dose inhalers in a double-blind crossover study to compare the effects on ventilation (VE), heart rate (fc) and oxygen uptake (VO2) at rest and at maximal and sub-maximal workloads. There were no significant differences in resting VE (p greater than 0.05) between the 4 treatment regimes. During submaximal exercise, VE at a given workload was greater after Fen containing treatment regimes than after Ip alone or placebo. There was no significant difference in the maximal workload achieved after the active treatments compared with placebo. With respect to fc and VO2, there were no differences between treatments at rest or on submaximal or maximal exercise. Fenoterol produces a mild stimulation of VE during exercise as observed with other beta-agonists, but compared with the changes in resting vital capacity, functional residual capacity and residual volume, the bronchodilator induced changes in exercise variables were relatively small.

Aged↗

PubMed1984

Ventilatory regulation in eucapnic morbid obesity.

In morbid obesity, there is an increased hindrance to breathing caused by the effects of the increased mass on the chest wall and abdomen; subjects with morbid obesity can maintain eucapnia by increasing inspiratory neuromuscular drive and/or by altering central breath timing. We studied 23 eucapnic, obese subjects (greater than 190% predicted ideal weight), 7 males and 16 females with a mean age of 36.6 +/- 9.2 yr and 18 healthy, normal male subjects. Total lung capacity, functional residual capacity, and total thoracic compliance were significantly (p less than 0.05) reduced in the obese subjects. At rest, minute ventilation was significantly increased because of an increase in respiratory frequency, which in turn was due to a significant decrease in the expiratory time (TE) per breath; the ratio of inspiratory to expiratory time (TI/TE) was thus significantly altered, indicating an alteration in central breath timing. Resting inspiratory neuromuscular drive (as represented by mouth occlusion pressure) was significantly increased in the obese subjects, but tidal volume was not significantly altered. There was an increased ventilatory responsiveness to hypoxia and relatively decreased ventilatory responsiveness to hypercapnia in the obese subjects. These results indicate that morbidly obese subjects maintain eucapnia primarily by an alteration in central breath timing. Although these subjects have decreased responsiveness to CO2, putting them at some risk of developing respiratory failure under conditions of hypercapnic/hypoxic stress, it is possible that this is counteracted by the increased responsiveness to hypoxia.

Adult↗

PubMed1993

Pulmonary function changes after large volume paracentesis.

Large volume paracentesis (LVP) is a safe, rapid, and effective treatment of ascites in cirrhotic patients. We investigated the effects of a 5-L aspiration of ascites on pulmonary function parameters in eight hemodynamically stable patients with cirrhosis and tense ascites. None had known lung disease or abnormal chest roentgenograms. At baseline, mean lung volumes, diffusing capacity, and arterial pO2 were all reduced from normal predicted values. Airflow, however, when related to lung volume, was normal. Post-LVP, lung volumes increased significantly; the mean expiratory reserve volume showed the greatest percent increase (105%) and correlated with the increases in the vital capacity, functional residual capacity, and total lung capacity. Airflow, the mean diffusing capacity, and arterial oxygenation were not significantly changed after LVP. We conclude that LVP significantly increases indices of lung volume but does not significantly alter parameters of airflow or gas exchange.

Ascites↗

PubMed2001

Relationship between pulmonary function and unsupported arm exercise in patients with COPD.

UNLABELLED: In patients with chronic obstructive pulmonary disease (COPD) the limitation on unsupported arm exercise (UAE) is predominantly respiratory muscle function-dependent. It is characterized by neuromechanical dysfunction (thoracoabdominal dyssynchrony) of the inspiratory muscles (diaphragm, accessory), superimposed by lung mechanics dysfunction. The undergoing mechanism is probably multifactorial. To study the relationship of resting pulmonary function and UAE performance in patients with COPD. Twenty-one patients, mean age 63 +/- 7 years, with COPD [forced expiratory volume in the first second (FEV1) 42 +/- 12% of predicted] underwent assessment of resting lung function (inspiratory capacity 57 +/- 17%; functional residual capacity 204 +/- 38% of predicted), maximal inspiratory pressure (67 +/- 14 cmH2O), upper arm circumference (30 +/- 2 cm), and symptom-limited cardiopulmonary UAE assessments. UAE consisted of bilateral anterior arm elevation to shoulder level at a rate of 40 arm strokes.minute-1. A series of stepwise multiple regression models were fitted to the data to predict exercise time from resting pulmonary function indices. RESULTS: Statistically significant correlations (r) were found between exercise time and inspiratory capacity (% of predicted) (r = 0.67, p = 0.0008), maximal inspiratory pressure (cmH2O) (r = 0.47, p = 0.03), upper arm circumference (r = 0.74, p = 0.0001), FEV1 (% of predicted) (r = 0.62, p = 0.0026), oxygen uptake (r = 0.56, p = 0.0085) and functional residual capacity (% of predicted) (r = -0.41, p = 0.06, borderline). Inspiratory capacity (% of predicted), functional residual capacity (% of predicted), upper arm circumference (cm) and FEV1 (% of predicted) explained 77% of the variance in exercise time. Therapeutic strategies that aim to increase inspiratory capacity or decrease functional residual capacity, or increase inspiratory muscle strength and upper arm/torso muscle endurance are likely to alleviate symptoms and improve UAE performance in patients with COPD.

Aged↗

PubMed2006

Remifentanil or sufentanil for coronary surgery: comparison of postoperative respiratory impairment.

BACKGROUND AND OBJECTIVE: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. METHODS: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5-1.0 microg kg(-1) min(-1)) or propofol/sufentanil (30-40 ng kg(-1) min(-1)) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. RESULTS: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). CONCLUSIONS: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

Aged↗

PubMed1989

Mechanism of action of ozone on the human lung.

Fourteen healthy normal volunteers were randomly exposed to air and 0.5 ppm of ozone (O3) in a controlled exposure chamber for a 2-h period during which 15 min of treadmill exercise sufficient to produce a ventilation of approximately 40 l/min was alternated with 15-min rest periods. Before testing an esophageal balloon was inserted, and lung volumes, flow rates, maximal inspiratory (at residual volume and functional residual capacity) and expiratory (at total lung capacity and functional residual capacity) mouth pressures, and pulmonary mechanics (static and dynamic compliance and airway resistance) were measured before and immediately after the exposure period. After the postexposure measurements had been completed, the subjects inhaled an aerosol of 20% lidocaine until response to citric acid aerosol inhalation was abolished. All of the measurements were immediately repeated. We found that the O3 exposure 1) induced a significant mean decrement of 17.8% in vital capacity (this change was the result of a marked fall in inspiratory capacity without significant increase in residual volume), 2) significantly increased mean airway resistance and specific airway resistance but did not change dynamic or static pulmonary compliance or viscous or elastic work, 3) significantly reduced maximal transpulmonary pressure (by 19%) but produced no changes in inspiratory or expiratory maximal mouth pressures, and 4) significantly increased respiratory rate (in 5 subjects by more than 6 breaths/min) and decreased tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1984

Use of the rebreathing method in the differential diagnosis of congenital heart disease and persistent fetal circulation.

The differential diagnosis of congenital heart disease from persistent fetal circulation is clinically difficult and cardiac catheterization is often needed. The development of a safe, new technique for use of the rebreathing method has allowed the determination of effective pulmonary blood flow, lung tissue volume, lung diffusion capacity and functional residual capacity in 7 critically ill, ventilator-dependent infants at the bedside. Analysis of the data revealed highly significant differences for lung tissue volume and diffusion capacity, a minimally significant difference for effective pulmonary blood flow and no difference for functional residual capacity between the groups. Use of this method allows not only attainment of clinically useful information but also permits better insight into the pathophysiology of the disease state.

Animals↗

PubMed1980

Pulmonary function in young children with alpha 1-antitrypsin deficiency: comparison with matched control subjects.

In this paper we report the initial cross-sectional data from a prospective study of pulmonary function in children with moderately severe and severe alpha 1-antitrypsin deficiency. Using a case-control design, our cases were 19 children 3 to 7 years of age with alpha 1-antitrypsin deficiency, Pi phenotype ZZ or SZ. Control subjects were selected from healthy children participating in a study to establish reference values for functional residual capacity and maximal expiratory flow at functional residual capacity, using a 1:1 match for sex, height, age, and weight. We found no significant difference between the cases and their matched control subjects with respect to functional residual capacity and maximal expiratory flow at functional residual capacity. We conclude that through 7 years of age there is no gross impairment in overall pulmonary function in children with moderately severe and severe alpha 1-antitrypsin deficiency, Pi phenotypes ZZ and SZ.

Child↗

PubMed1991

Contractile properties of the human diaphragm during chronic hyperinflation.

BACKGROUND: In patients with chronic obstructive pulmonary disease (COPD) and hyperinflation of the lungs, dysfunction of the diaphragm may contribute to respiratory decompensation. We evaluated the contractile function of the diaphragm in well-nourished patients with stable COPD, using supramaximal, bilateral phrenic-nerve stimulation, which provides information about the strength and inspiratory action of the diaphragm. METHODS: In eight patients with COPD and five control subjects of similar age, the transdiaphragmatic pressure generated by the twitch response to phrenic-nerve stimulation was recorded at various base-line lung volumes, from functional residual capacity to total lung capacity, and during relaxation and graded voluntary efforts at functional residual capacity (twitch occlusion). RESULTS: At functional residual capacity, the twitch transdiaphragmatic pressure ranged from 10.9 to 26.6 cm of water (1.07 to 2.60 kPa) in the patients and from 19.8 to 37.1 cm of water (1.94 to 3.64 kPa) in the controls, indicating considerable overlap between the two groups. The ratio of esophageal pressure to twitch transdiaphragmatic pressure, an index of the inspiratory action of the diaphragm, was -0.50 +/- 0.05 in the patients, as compared with -0.43 +/- 0.02 in the controls (indicating more efficient inspiratory action in the patients than in the controls). At comparable volumes, the twitch transdiaphragmatic pressure and esophageal-to-transdiaphragmatic pressure ratio were higher in the patients than in normal subjects, indicating that the strength and inspiratory action of the diaphragm in the patients were actually better than in the controls. Twitch occlusion (a measure of the maximal activation of the diaphragm) indicated near-maximal activation in the patients with COPD, and the maximal transdiaphragmatic pressure was 106.9 +/- 13.8 cm of water (10.48 +/- 1.35 kPa). CONCLUSIONS: The functioning of the diaphragms of the patients with stable COPD is as good as in normal subjects at the same lung volume. Compensatory phenomena appear to counterbalance the deleterious effects of hyperinflation on the contractility and inspiratory action of the diaphragm in patients with COPD. Our findings cast doubt on the existence of chronic fatigue of the diaphragm in such patients and therefore on the need for therapeutic interventions aimed at improving diaphragm function.

Aged↗

PubMed1988

Maximum respiratory pressures in morbidly obese subjects.

Maximum inspiratory and expiratory pressures were measured at residual volume, total lung capacity, and functional residual capacity in 45 morbidly obese patients who on average weighed 183% of their predicted weights. The pressures were compared to determinations made in 25 subjects of similar age whose mean weight was 99% of predicted. For both men and women, pressures generated by control subjects tended to be higher than those produced by obese patients but the differences were not statistically significant. The mean vital capacity and total lung capacity were also similar in the 2 subject groups. The results indicate that despite working constantly against a less compliant chest wall, obese patients do not increase their capacity to generate maximal respiratory pressures.

Adult↗

PubMed1982

Effect of immersion on RV in young women: implications for measurement of body density.

The effect of immersion to the chin on the residual volume (RV), vital capacity (VC), functional residual capacity (FRC), and expiratory reserve volume (ERV) of 27 normal females, mean age 20.7 years, was studied. Mean determinations decreased (P less than .01) for all measured lung volumes from the corresponding measurement with the subjects in air (RV 17.4%, VC 12.1%, FRC 46.9%, ERV 70.3%). In addition, the effect of the decreased RV on body density (Db) and percent fat (% fat) determinations were also examined. The mean reduction in RV of 17.4% (195 ml) corresponded to a mean relative error of only 0.35% in the Db measure. It is recommended that when measuring RV to later determine Db by hydrostatic weighing, the determination be made with subject in air. This procedure will allow for greater ease in measurement for both the subject and researcher with no loss in physiologic accuracy.

Adult↗

PubMed1998

Myosin heavy chain gene expression changes in the diaphragm of patients with chronic lung hyperinflation.

In striated muscle, chronic increases in workload result in changes in myosin phenotype. The aim of this study was to determine whether such changes occur in the diaphragm of patients with severe chronic obstructive pulmonary disease, a situation characterized by a chronic increase in respiratory load and lung volume. Diaphragm biopsies were obtained from 22 patients who underwent thoracic surgery. Myosin was characterized with electrophoresis in nondenaturing conditions, SDS-glycerol PAGE, and Western blotting with monoclonal antibodies specific for slow and fast myosin heavy chain (MHC) isoforms. Flow volume curves, total lung capacity, and functional residual capacity were measured before surgery in 20 patients. We found that the human diaphragm is composed of at least four myosin isoforms, one slow and three fast, resulting from the combination of three MHC species. Chronic overload was associated with an increase in the slow beta-MHC species at the expense of the fast species (beta-MHC, 78.2 +/- 4.6 and 50.0 +/- 6.5% in emphysematous and control patients, respectively; P < 0.005). Linear correlations were found between beta-MHC percentage and forced expiratory volume in 1 s (r = -0.52; P < 0.02), total lung capacity (r = 0.44; P < 0.05), and functional residual capacity (r = 0.65; P < 0.003). The human adult diaphragm is composed of a balanced proportion of slow and fast myosin isoforms. In patients with chronic obstructive pulmonary disease, the proportion of fast myosins decreases, whereas that of slow myosin increases. This increase appears to be closely related to lung hyperinflation and may reflect an adaptation of the diaphragm to the new functional requirements.

Adult↗

PubMed1981

Effect of systemic venous hypertension on pulmonary function and lung water.

We studied the effects of systemic venous hypertension (SVH) of 25 cmH2O, with and without fluid overload (100 ml.kg-1.h-1 x 4 h), on the lung water content and pulmonary function of anesthetized dogs. SVH was produced by inflating a balloon in the right atrium. Pulmonary extravascular water (PEW) was measured by gravimetric techniques taking the water content of trapped blood into consideration. Subdivisions of lung volume, pulmonary resistance, dynamic compliance, and the single-breath nitrogen washout curve were performed in a body plethysmograph. Vascular pressures, serum oncotic pressure, and arterial blood gases were also measured. Systemic venous hypertension alone produced no change in lung water content (control PEW = 3.46 +/- 0.16; SVH PEW = 3.44 +/- 0.18 g H2O/g dry tissue, mean +/- SD) or alterations in pulmonary function. Fluid overload alone produced an insignificant increase in PEW (4.24 +/- 0.72 g H2O/g dry tissue) and decreases in vital capacity and functional residual capacity. SVH in combination with fluid overload resulted in a significant increase in lung water (4.78 +/- 1.03 g H2O/g dry tissue) and decreases in functional residual capacity, vital capacity, dynamic compliance, and arterial blood oxygen tension as well as increased pulmonary resistance. We conclude that SVH favors the formation of pulmonary edema under conditions of increased pulmonary transcapillary fluid exchange and may particularly augment airway edema.

Airway Resistance↗