Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Closing Volume”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed1989

Single breath N2 washout in papain-induced pulmonary emphysema.

Single breath nitrogen washout tests were analyzed in dogs (n = 8) with healthy lungs and after development of emphysema. The animals were in the supine position and studied during anaesthesia and mechanical ventilation (FiO2 = 0.4, FiN2 = 0.6). During controlled expiration with constant flow (VE = 0.15 l/s) onset of phase IV of the alveolar plateau was related to airway closure of dependent lung regions (closing volume CV). In the control state, CV accounted for 6.2 +/- 1.5% VC, and closing capacity (CC) was lower than functional residual capacity (FRC). Likewise, gas exchange was normal in all animals (PaO2 = 24.7 +/- 3.32 kPa, PaCO2 = 5.18 +/- 0.53 kPa, PA-aO2 = 2.6 +/- 0.3 kPa). Panlobular emphysema (PLE) was induced by inhalation of papain (100 mg/kg). After three weeks development of PLE was documented by measurements of lung volumes (functional residual capacity (FRC), expired vital capacity (EVC), total lung capacity (TLC), residual volume (RV], pulmonary mechanics (dynamic and static compliance (Cdyn, Cstat), mean airway resistance (Raw], gas exchange (PaO2, PaCO2, PA-aO2), and by radiomorphological analysis. In the PLE-group, FRC and RV (p less than or equal to 0.05), and Cstat (p less than or equal to 0.01) were significantly elevated. CV increased to 16.2 +/- 2.7% VC (p less than or equal to 0.01) and CC exceeded FRC by 80 ml, indicating that tidal volume breathing took place within the range of closing volume. Oxygenation was significantly impaired (PaO2 = 18.6 +/- 3.72 kPa, PA-aO2 = 6.5 +/- 1.1 kPa, p less than or equal to 0.05), but not CO2-elimination. Pathological analysis by radiomorphological means showed dissiminate parenchymal lesions compatible with emphysema of grade II severity located predominantly in subpleural areas. In dogs with papain-induced PLE, premature closure of dependent airways is enhanced, which is due to structural changes and a loss of elastic recoil in the lungs.

Animals↗
PubMed1996

Three-Dimensional Echocardiographic Reconstruction of the Left Ventricle by a Transesophageal Tomographic Technique: In Vitro and In Vivo Validation of its Volume Measurement.

Accurate determination of left ventricular (LV) volume has important therapeutic and prognostic implications in patients with cardiac disease. Volume estimations by two-dimensional techniques are not very accurate due to geometric assumptions. OBJECTIVES: To validate LV volume determinations by a new transesophageal three-dimensional echocardiographic technique. We performed three-dimensional reconstruction of the LV using an echo-computed tomographic (CT) technique based on serial pullback parallel slice imaging technique in both in vitro and in vivo settings. Fourteen latex balloons with various sizes (30-235 mL) and shapes (conical, pear shaped, round, elliptical, and aneurysms in various locations) filled with known volumes of water were imaged in a water bath. From the static three-dimensional image, the LV long axis was defined and the LV was sectioned perpendicular to this axis into 2-mm slices. The volume of each slice was calculated with the observer blinded to the actual volume as the product of the slice thickness and the manually traced perimeter of the slice and the LV volume as the sum of the volumes of the slices (Simpson's method). The calculated LV volume closely correlated with the actual volume (r = 0.99, P < 0.0001, calculated volume = 1.06x - 11.3, Deltavolume = -5.7 +/- 10.0 cc). Using the same system, transesophageal echocardiographic (TEE) images of the LV were obtained in 15 patients gated to respiration and ECG. Satisfactory dynamic three-dimensional reconstruction of the LV was possible in ten patients. The three-dimensional LV volumes (systolic and diastolic) using Simpson's method correlated well with those obtained from biplane or multiplane TEE images using the area length method (r = 0.89, p < 0.0001, y = 12.7 + 0.84x, Deltavolume = 1.3 +/- 18.1 cc). The LV major-axis diameters by the two methods showed very close correlations as well (r = 0.86, P < 0.0001, y = 19 + 0.74x, Deltadiameter = 1.0 +/- 7.2 mm). We conclude that three-dimensional LV volume calculation by the echo-CT technique is intrinsically sound, is independent of LV geometry, and with some limitations, is applicable in vivo. (ECHOCARDIOGRAPHY, Volume 13, November 1996)

Journal Article↗
PubMed1984

Lung volume measurement during closed circuit anesthesia.

Lung volume measurement can be of interest to anesthesists as well as respiratory physicians, both as a diagnostic tool and as a way to monitor the effect of respiratory therapy (for instance PEEP ventilation). Several methods exist to measure lung volume. Only two of them can be applied easily during mechanical ventilation. The wash-in wash-out of insoluble inert gas can be used in non-rebreathing (semi open) systems, or the equilibration of an inert insoluble gas which can be used in completely closed systems. In our department a completely closed anesthesia system has been developed which is particularly well suited for the equilibration method of lung volume measurement. Just like the wash-out method, the equilibration method can give information about the uniformity of ventilation-distribution within the lung.

Anesthesia↗
PubMed1989

The ventilatory effect of external oscillation.

High frequency ventilation (HFV) may be achieved by external oscillation (external HFV) applied around the chest wall (HFCWO) in large animals and humans, or over the entire body (HFBSO) in small animals, instead of being applied via the trachea (internal HFV). We present a synthesis of the results obtained with external HFV in both normal and bronchoconstricted subjects. Whereas external and internal HFV were found to be equivalent in terms of gas exchange in normal rats, external HFV was found to have a beneficial effect in bronchoconstricted rabbits, but internal HFV did not. From the frequency-oscillatory tidal volume relationship determined in normocapnic rabbits, HFBSO at 5 Hz was found to be the optimal frequency at which to ventilate with tidal volumes close to the dead space volume, and which was also shown to be the optimal volume to obtain normocapnia. Moreover, 5 Hz oscillations (HFCWO) at 20 ml and 40 ml superimposed on tidal breathing accelerated nitrogen washout, i.e., gas exchange in normal humans. Unfortunately, only oscillations with much smaller volumes (5-10 ml) were obtainable in COPD patients. Nevertheless, they produced a clear change in breathing pattern associated with a slight improvement in gas exchange and a potentially positive effect on inspiratory muscle fatigue. These results support the concept that non-invasive external HFV technique may be of use in assisting ventilation in bronchoconstricted subjects and may possibly replace conventional controlled ventilation, at least in subjects with high lung compliance, such as babies, neonates and normal adults.

Animals↗
PubMed1981

Reference values for respiratory function tests in males: prediction formulas with tobacco smoking parameters.

Prediction equations for respiratory function tests were obtained by multiple regression of data from 263 healthy males. The material was evenly distributed in the ages 20-70 years, about one third each of non-smokers, smokers and ex-smokers. Measurements were done of lung volumes (with body plethysmograph), airways resistance, ventilatory capacity including flow-volume registration, gas distribution and closing volume, transfer factor and static elastic recoil pressures of the lung with calculation of static compliance. The parameters age, height, weight, years of tobacco smoking and grams of tobacco smoked each day showed significant correlation with the outcome of the test in most of the respiratory function tests. Therefore a set of basic regression equations including these parameters were calculated. In addition an 'extended' set of equations was calculated for prediction of some tests with inclusion of nonlinear terms and the parameter 'years of abstinence from smoking.' The reduction in variance which followed inclusion of tested parameters was moderate (20-69%). There were significant differences between results of the present study and several previously published regression formulas.

Adolescent↗
PubMed1984

Alveolar ventilation during high-frequency oscillation: core dead space concept.

To assess the role of direct alveolar ventilation during high-frequency ventilation, we studied convective gas mixing during high-frequency oscillation with tidal volumes close to the dead space volume in a simple physical model. A main conduit representing a large airway was connected with a rigid sphere (V = 77, 517, and 1,719 cm3) by a small circular tube (d = 0.3 and 0.5 cm; L = 5, 10, and 20 cm). The efficiency of sinusoidal oscillations (f = 5, 20, and 40 Hz) applied at one end of the main conduit was assessed from the washout of a CO2 mixture from the sphere; to flush CO2 from the main fluid line, a constant flow of air was used. The decay in CO2 concentration measured in the sphere was exponential and therefore characterized by a measured time constant (tau m). Taking the small tube volume as the ventilatory dead space (VD), an effective tidal volume (VT*) was computed from tau m and compared with the tidal volume (VT) obtained separately from the pressure variation in the sphere. The discrepancy between these two tidal volumes has been found to be uniquely dependent on the ratio VT/VD within the range of VT/VD studied (0.5-2.2). For VT/VD less than 1.2, VT* was larger than VT, indicating that the conventional concept of alveolar ventilation does not apply. From the partition of the oscillatory flow in the small tube into two regions, the core and the unsteady boundary layer, we theoretically computed the proportions of the sinusoidal flow (or tidal volume) and the dead space for each region.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Hazards of hospitalization of the elderly.

For many older persons, hospitalization results in functional decline despite cure or repair of the condition for which they were admitted. Hospitalization can result in complications unrelated to the problem that caused admission or to its specific treatment for reasons that are explainable and avoidable. Usual aging is often associated with functional change, such as a decline in muscle strength and aerobic capacity; vasomotor instability; reduced bone density; diminished pulmonary ventilation; altered sensory continence, appetite, and thirst; and a tendency toward urinary incontinence. Hospitalization and bed rest superimpose factors such as enforced immobilization, reduction of plasma volume, accelerated bone loss, increased closing volume, and sensory deprivation. Any of these factors may thrust vulnerable older persons into a state of irreversible functional decline. The factors that contribute to a cascade to dependency are identifiable and can be avoided by modification of the usual acute hospital environment by deemphasizing bed rest, removing the hazard of the high hospital bed with rails, and actively facilitating ambulation and socialization. The relationships among physicians, nurses, and other health professionals must reflect the importance of interdisciplinary care and the implementation of shared objectives.

Accidental Falls↗
PubMed2005

Influence of mimic cardiac rate on hydrodynamics of different mechanical prosthetic cardiac valves in vitro.

OBJECTIVE: To assess the influence of mimic cardiac rate on hydrodynamics of different mechanical prosthetic cardiac valves. METHODS: US-made CarboMedics bileaflet valve, China-made Jiuling bileaflet valve and C-L tilting disc valve were tested via a pulsatile flow simulator in the aortic position. Testing conditions were set at mimic cardiac rates of 55 bpm, 75 bpm, 100 bpm with a constant mimic cardiac output of 4 L/min. The mean pressure differences (deltaP), leakage volumes (L(E)V) and closing volumes (C(L)V) across each valve, and effective orifice areas (EOA) were analyzed. RESULTS: Within physiological range, deltaP, L(E)V, and C(L)V decreased as mimic cardiac rate increased, with a large extent of variance. EOA increased along with an increase in mimic cardiac rate. It was a different response in terms of cardiac rate alteration for different types of mechanical prosthetic cardiac valves. CONCLUSION: Mimic cardiac rate change affects hydrodynamics of mechanical prosthetic cardiac valves. Within physiological range, the hydrodynamic of prosthetic bileaflet valve is better than that of tilting disc valve.

Biomechanical Phenomena↗
PubMed1989

Lung function in adolescents after uncomplicated whooping cough in childhood.

Ventilatory function (forced vital capacity, forced expiratory volume in one second, forced expiratory flows), static lung volumes, phase III slope and closing volume (single-breath nitrogen washout test) were measured in 499 children and adolescents aged 10-16 yrs from a general population sample in North-East France. A history of whooping cough was given by 44 children (22 of each sex); their results were compared to those of the 455 children (215 girls) with a negative history. The only difference between the two groups was a minimal increase in the residual volume/total lung capacity ratio in cases (19.2 +/- 3.1 vs 18.0 +/- 2.9%). We conclude that uncomplicated whooping cough in early childhood did not lead to significant pulmonary function abnormality in this population of children born after 1967.

Adolescent↗
PubMed1978

[Frequency of lung function disturbances of industrial poultry farmers (author's transl)].

The frequency of antibodies against organic dusts of fowls were examined on 339 poultry farmers. 22% of workers had 1 antibody and 3% had 2 antibodies in the serum. The ventilation, the arterial oxygen tension, the residual volume, the Slope Index, the closing volume of each person were measured in the mobile laboratory. Signs of central obstruction and equal ventilation were found in sensitized persons (2 antibodies) about four times more than non-sensitized persons. Suitable lung function screening parameters were the FEV1/FVC and the Slope Index.

Allergens↗
PubMed1982

Pulmonary functions during peritoneal dialysis.

Lung volumes, flows, flow volume loop, diffusing capacity and closing volume were studied in 7 patients (Group I) before, with 2 liter dialyzate in the peritoneal cavity and after 8 hours of peritoneal dialysis. The functional residual capacity, residual volume and the total lung capacity decreased (P less than 0.01, less than 0.05, and less than 0.05 respectively) with 2 liter dialyzate in the peritoneal cavity and returned to baseline after the dialyzate was removed. Arterial blood gas analysis was performed in another 8 patients (Group II) before, with 2 liter dialyzate in the peritoneal cavity, and after the dialyzate had been drained. No significant difference was observed in PaO2, PaCO2 or pHa during any phase of the study. It is concluded that except for a minor decrease in FRC, RV and TLC, there were no deleterious effects with the use of 2 liter dialyzate volume on gas exchange or pulmonary functions during peritoneal dialysis.

Adult↗
PubMed1978

Pulmonary function abnormalities in asymptomatic children after hydrocarbon pneumonitis.

To assess the effect of hydrocarbon pneumonitis on the developing lung, we studied the pulmonary function of 17 asymptomatic children, 8 to 14 years after the initial insult. Fourteen of the 17 subjects (82%) had one or more pulmonary function abnormalities, the most frequent being a high volume of isoflow. Volume of isoflow, ratio residual volume to total lung capacity, slope of phase III, flow rates at 50% and 25% of vital capacity and 60% of the total lung capacity, one-second forced expiratory volume, and maximum midexpiratory flow rate differed significantly (P less than .05) from values in control groups. Closing volume and closing capacity were not significantly different. Residual abnormalities present in children after hydrocarbon pneumonitis can be explained on the basis of small airway obstruction and/or loss of elastic recoil. These children may be at risk for the development of chronic lung disease as adults when they are exposed to exogenous factors such as air pollution or smoking.

Child, Preschool↗
PubMed1980

[Lung function, gas exchange and regulation of ventilation in patients with portocaval encephalopathy (author's transl)].

In 17 patients, breathing room air and pure oxygen, with histologically proven cirrhosis of the liver and portocaval encephalopathy grade I, static and dynamic lung volumes, closing capacity and arterial blood gases were determined. Furthermore, CO2, response curves were provided and mouth occlusion pressure measurements were carried out. The residual volume was found to be increased (130 +/- 8% of predicted) which resulted in decreased vital capacity (79 +/- 2% of predicted) with total lung capacity being normal (94 +/- 2% of predicted). Closing capacity was increased to 134 +/- 5% of the predicted value. Gas exchange for oxygen was impaired (AaDO2 = 262 +/- 30% of predicted). Arterial PO2, however, was within normal range PaO2 = 84 +/- 3.6 mm Hg) due to hyperventilation (PaCO2 = 28.1 +/- 0.8 mm Hg). Hypoxic ventilatory stimulation could be excluded because inspiration of pure oxygen caused no change of PaCO2 (PaCO2 = 27.3 + 0.7 mm Hg and PaO2 = 465 + 16.9 mm Hg with FIO2 = 1.0). The slope of the CO2 response curves was normal, the mouth occlusion pressures, however, were higher than the predicted value: up to PaCO2 of 55 mm Hg. The slope of these curves being smaller than predicted. The results show that in patients with portocaval encephalopathy the lung function is disturbed due to premature airway closure with consequently decreased regional ventilation: perfusion ratios and that regulation of ventilation is impaired by a loss of sensitivity for CO2 with high basal output of the respiratory centers not related to CO2.

Blood Gas Analysis↗
PubMed1988

Running-induced changes in lung function are not altered by acute moderate hypoxia.

The purpose of this study was to describe the acute changes in pulmonary function and volumes induced by running in a simulated normobaric hypoxic environment. Eleven men (X- = 26 years, 78 kg) ran 5 miles (run time approximately equal to 40 min) under normoxic (N) and hypoxic (H) conditions. A PO2 Aerobic Exerciser was used to approximate an altitude of 2286 m (PIO2 = 113 mm Hg). Impedance cardiography was used to measure cardiac output and segmental transthoracic impedance (Zo) was used to identify thoracic fluid shifts. Similar reductions in vital capacity (7%) and increases in residual volume (10%) occurred after the N and H runs with no change in total lung capacity. Flow rates breathing air or He/O2, closing volume, and closing capacity did not change. The DLCO breathhold maneuver caused a significant fall in pulmonary blood flow after running but diffusing capacity appeared to be unaffected. No changes occurred in Zo at the apex, middle, or base of the lung after either run. The hypoxic pulmonary pressor response failed to modify the pulmonary changes observed after equivalent normoxic exercise. The lung volume changes subsequent to either run were due to expiratory limitation. Previous speculation of an exercise-induced interstitial edema could not be confirmed.

Adult↗
PubMed1982

Hyperinflation on hyperventilation-a simple test to detect early airway disease.

The hypothesis was raised that an increased end-expiratory lung volume when switching over from normal to hyperventilation (positive delta FRC) can be used as a criterion of early obstructive lung disease. In 20 normal subjects and in 24 patients with suspect or manifest lung disease delta FRC at breathing frequencies of 40, 60 and 80 min-1, forced expiratory volume in one second (FEV1), vital capacity (VC), maximal expiratory flow at 50 and 25% of VC (MEF50 and MEF25) and closing volume (CV) were determined. FEV% (FEV1 X VC-1 X 100) and CV% (CV X VC-1 X 100) were calculated. delta FRC40 correlated negatively with FEV%, MEF50 and MEF25 for normals and patients separately with no difference between the groups. The residual standard deviation of delta FRC40 on FEV% was significantly reduced when MEF50 and MEF25 was included. delta FRC40 did not correlate with CV or CV%. delta FRC60 and delta FRC80 did not correlate with MEF50 and MEF25. The reproducibility of delta FRC40 was of the same order as the other variables studied. A delta FRC40 of +0.31 corresponded to MEF50 and MEF25 values 2 SD below the reference value. This suggests that a positive delta FRC40 of more than 0.31 indicates airway obstruction.

Adolescent↗
PubMed1980

Site and type of impaired lung function in extrinsic allergic alveolitis.

We investigated 109 persons exposed and sensitized against organic antigens. 46 of them (group I) are affected with the typical clinical and roentgenological signs of allergic alveolitis. The other 59 subjects (group II) were sensitized only. Included in all examinations were immunological diagnosis by means of counterimmunoelectrophoresis, systematic interviewing for case histories, and registration of respiratory symptoms. Pulmonary function was recorded by means of the following techniques: analysis of ventilation (flow-volume indices), respiratory mechanics of the larger airways and lung (body plethysmography, esophageal balloon technique), respiratory mechanics of the small airways (closing volume, amplitude of cardiogenic oscillations), distributional analysis, diffusion analysis, blood gas analysis, and right heart catheterization. Extrinsic allergic alveolitis caused changes in lung mechanics, in airways as well as in lung tissue. The most impressive findings in allergic alveolitis are mechanical inequalities of ventilation. These inequalities may be caused by changed mechanics of overall airways indicated by obstruction parameters and by changed structure of lung tissue reflected in decreased compliance, transfer factors and increased pulmonary arterial pressure. Not only a restrictive but also an obstructive disturbance of ventilation is found. Impairments are less in sensitized persons. We find slight mechanical and ventilatory inhomogeneities. An overall airway obstruction is obvious but not to such a large extent as in allergic alveolitis. On the contrary, here the lung tissue is not affected. Compliance and diffusion are within the normal range. There is no typical functional pattern specific for the diagnosis of allergic alveolitis.

Adult↗
PubMed1976

Closing capacity measurement during general anesthesia.

A modification of the single-breath nitrogen closing volume (CV) test allows measurement of closing capacity (CC) during general anesthesia. In the modification, inspiration and expiration are mechanically produced by a hydraulically powered cylinder. For 14 awake, normal subjects results of the CV test performed using this mechanical method differed that those obtained following spontaneous inspiration and expiration. Mean (+/-SE) CC's were 2.25 (+/-0.15) and 2.42 1 (+/-0.14) (P less than 0.01) using spontaneous and mechanical methods, respectively. The slopes of Phase III of the CV traces were 2.24 (+/-0.27) and 2.66 per cent N2/L (+/-0.32) (P less than 0.01), respectively. To eliminate differences due to measurement technique, the modified CV test was used both before and during anesthesia with halothane in 70 per cent N2 in 11 normal, supine, spontaneously breathing subjects. CC's were 1.89 l (+/-0.16) before and 1.84 l (+/-0.15) during anesthesia (P greater than .5). Mean functional residual capacities (FRC) by the closed-circuit helium method were 1.77 l (+/-0.15) before and 1.45 l (+/-0.17) during anesthesia (P less than .001). With CC unchanged and FRC decreased following induction, CC/FRC increased from 1.07 (+/-0.08) to 1.37 (+/-0.11) (P less than .005), suggesting increased small-airway closure during anesthesia.

Adult↗
PubMed1997

Mechanism of posturally induced crackles as predictor of latent congestive heart failure.

We investigated the role of changes in pulmonary function in posturally induced crackles (PIC) in 76 patients with various heart diseases. Regional ventilation was evaluated by spirometric gated ventilation scanning using 133Xe in 23 of these patients and its relationship to PIC was analyzed. A change from the sitting to the supine position was associated with a significant decrease in the percent functional residual capacity (FRC, p < 0.01) and significant increases in closing volume (CV), CV/vital capacity (VC) and closing capacity (CC)/FRC (p < 0.01) in the PIC-positive subjects. CV, CV/VC and CC/FRC did not differ significantly between PIC-positive (n = 37) and PIC-negative (n = 39) subjects in the sitting position, but in the supine position, these values were significantly higher in the PIC-positive group than in the PIC-negative group (CV: p < 0.05, CV/VC and CC/FRC: p < 0.01). These results suggest that airway closure was markedly increased in PIC-positive subjects in the supine position compared with PIC-negative subjects. Regional ventilation (V) was assessed in the sitting and the supine position from right lateral images divided into 9 segments from the base to the apex of the lung using spirometric gated ventilation scanning. There was no significant difference in regional ventilation in the sitting position between PIC-negative (n = 11) and PIC-positive (n = 12) subjects; in the supine position, regional ventilation decreased significantly at the base in the PIC-positive group. Findings suggest that PIC at the base of the lungs may be related to airway closure at the base of the lungs in the supine position in PIC-positive subjects.

Adult↗