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PubMed1978

Effects of age on regional residual volume.

Forty-one normal non-smokers between the ages of 20 and 80 were studied to determine if the increased residual volume, known to occur with aging, results from increased residual volume throughout, or only in specific regions of the lung. The subjects were dividied into groups consisting of 20-29, 30-39, 40-49, 50-69, and 70+ yr. Measurements of regional residual volume to regional total lung capacity ratio (RVr/TLCr) were made using zenon-133 and a multidetector analysis system in which five zones (from top to bottom) were analyzed in each lung. Closing volume was also measured. The subjects were in the sitting position for all studies. The results showed regardless of age, the RVr/TLCr was higher at the top than at the bottom of the lung. In addition, the ratio of upper to lower RVr/TLCr was not significantly different between any of the age groups. The results can be explained if airways throughout the lung close at higher volumes as age increases, or if altered emptying sequences within regions occur due to retarded emptying of highly compliant lung regions.

Adult↗
PubMed1983

Effect of previous volume history on airway closure.

We studied the effect of volume history on airway closure in six healthy males ranging from 32 to 67 yr of age. The method used was to compare the regional distribution of 133Xe boluses distributed according to N2O uptake during open-glottis breath-hold maneuvers with the regional distribution of boluses of intravenously injected 133Xe. Measurements were made at two lung volumes, one close to residual volume (RV) and the other just below closing volume. The required volume was reached either by expiring from total lung capacity or by inspiring from RV. Although there was considerable airway closure in the basal regions of the lungs at both lung volumes studied, the degree of airway closure was not dependent on the previous volume history. We conclude that the airways concerned with closure have a volume-pressure hysteresis similar to that of the lung parenchyma. Furthermore in normal humans the volume-pressure hysteresis of the lung is not secondary to airway closure.

Adult↗
PubMed1976

Bronchoconstriction and pulmonary hypertension during abortion induced by 15-methyl-prostaglandin F2alpha.

Patients have experienced severe breathlessness during second trimester abortion initiated by the intramuscular injection of 15-methyl-prostaglandin F2alpha (15-me-PGF2alpha). In four healthy women given 400 mug of 15-me-PGF2alpha to induce abortion, pulmonary function tests showed reductions in arterial oxygen tension, maximum expired air flow and vital capacity. Residual lung volume and the slope of phase III of the closing volume curves increased.

Abortion, Induced↗
PubMed1995

Comparison of static conformal field with multiple noncoplanar arc techniques for stereotactic radiosurgery or stereotactic radiotherapy.

PURPOSE: Compare the use of static conformal fields with the use of multiple noncoplanar arcs for stereotactic radiosurgery or stereotactic radiotherapy treatment of intracranial lesions. Evaluate the efficacy of these treatment techniques to deliver dose distributions comparable to those considered acceptable in current radiotherapy practice. METHODS AND MATERIALS: A previously treated radiosurgery case of a patient presenting with an irregularly shaped intracranial lesion was selected. Using a three-dimensional (3D) treatment-planning system, treatment plans using a single isocenter multiple noncoplanar arc technique and multiple noncoplanar conformal static fields were generated. Isodose distributions and dose volume histograms (DVHs) were computed for each treatment plan. We required that the 80% (of maximum dose) isodose surface enclose the target volume for all treatment plans. The prescription isodose was set equal to the minimum target isodose. The DVHs were analyzed to evaluate and compare the different treatment plans. RESULTS: The dose distribution in the target volume becomes more uniform as the number of conformal fields increases. The volume of normal tissue receiving low doses (> 10% of prescription isodose) increases as the number of static fields increases. The single isocenter multiple arc plan treats the greatest volume of normal tissue to low doses, approximately 1.6 times more volume than that treated by four static fields. The volume of normal tissue receiving high (> 90% of prescription isodose) and intermediate (> 50% of prescription isodose) doses decreases by 29 and 22%, respectively, as the number of static fields is increased from four to eight. Increasing the number of static fields to 12 only further reduces the high and intermediate dose volumes by 10 and 6%, respectively. The volume receiving the prescription dose is more than 3.5 times larger than the target volume for all treatment plans. CONCLUSIONS: Use of a multiple noncoplanar conformal static field treatment technique can significantly reduce the volume of normal tissue receiving high and intermediate doses compared with a single isocenter multiple arc treatment technique, while providing a more uniform dose in the target volume. Close conformation of the prescription isodose to the target volume is not possible using static uniform conformal fields for target shapes lacking an axis of rotational symmetry or plane of mirror symmetry.

Brain Neoplasms↗
PubMed1986

Comparison of lung volume measurements by single breath helium and multiple breath nitrogen equilibration methods in normal subjects and COPD patients.

The validity of the single breath helium dilution method for accurate measurement of the total lung capacity (TLC) was investigated. Comparison was made with the multiple breath nitrogen equilibration technique in 22 normal subjects and 37 patients with chronic obstructive pulmonary disease (COPD). The single breath method underestimated the TLC in all the normal individuals and 33 of 37 patients with COPD. Possible explanations for the falsely low lung volumes include uneven distribution of inspired air due to closing volumes and induced bronchoconstriction.

Adult↗
PubMed1975

Pulmonary function in asymptomatic adolescents with idiopathic scoliosis.

Pulmonary function studies were performed in 28 asymptomatic adolescents with idiopathic scoliosis. Tests included spirometry, flow volume curve, measurements of inspired gas distribution, diffusing capacity, closing volume, ventilatory response to carbon dioxide, and arterial blood gas analysis. In addition to the well-known decreases in lung volumes, a reduction in diffusing capacity, arterial oxygen tension, and ventilatory response to carbon dioxide were also documented. Significant correlations existed between the severity of the spinal curvature and the decrease in lung volumes. A significant correlation was also found between the degree of hypoxemia and the reduction in the diffusing capacity, suggesting that a low diffusing could be the cause of the observed arterial hypoxemia.

Adolescent↗
PubMed1981

Increased lung stiffness of persons with pleural plaques.

Forty-five men with asbestos-related pleural plaques detected at a health screening centre were investigated with measurement of lung volumes, airways resistance, ventilatory capacity, transfer factor, gas distribution, closing volume and static recoil pressures of the lung. The men were subjectively healthy, had confirmed exposure to asbestos and had normal chest radiograms apart from the presence of pleural plaques. Most of the men had been exposed to small or moderate amounts of asbestos with a mean duration of 39 years since first exposure. Sixty-seven per cent of the men were smokers or ex-smokers. The lung function was evaluated using regression formulas which included smoking variables. The results clearly demonstrate the presence of lung parenchymal involvement with increased stiffness of the lungs and decreased lung volumes. The change in elastic recoil pressure of the lungs, in total lung capacity and residual volume show significant correlation with measures of asbestos exposure and extent of pleural changes. No synergistic effects between tobacco smoking and asbestos exposure on lung function could be demonstrated. Measurements of the static elastic lung recoil (Pst(max) and Cst/TLC) and total lung capacity were the most sensitive tests for separating the pleural plaque carriers from the controls.

Aged↗
PubMed1981

Vertical distribution of perfusion and inspired gas in supine man.

In order to specify if a closing volume greater than expiratory reserve volume could influence the distribution of perfusion (Qr), we measured vertical Qr in 6 supine subjects before and after inhalation of an oxygen enriched gas mixture. In addition, we studied Qr and inhaled gas (V alv.) at different lung volumes. We observed a preferential perfusion of non-dependent zones of the supine lung during tidal breathing from FRC correlated to the amount of airway closure represented by the difference between FRC and closing capacity. After oxygen breathing, the distribution of perfusion is reversed and flow is preferentially distributed in the dependent zones of the supine lung. This O2 sensitive effect was time and/or volume history dependent since Qr distribution at FRC after a breath to total lung capacity was similar to that after 3 min of tidal breathing with oxygen mixture. At FRC, the ventilation was preferentially distributed to the non-dependent lung zones. The vertical gradient of both Qr and V alv. increased progressively at higher lung volumes and Va/Q ratios were usually greater in non-dependent zones.

Adult↗
PubMed1981

High-frequency animal ventilator using a loudspeaker and its gas exchange characteristics.

A high-frequency ventilator was designed using a loudspeaker as a piston, driven by a power-amplifier. A sine-wave signal was introduced into the amplifier from an electronic oscillator. The mechanical and gas exchange characteristics of the ventilator were studied in vitro and in dogs. The volume output per stroke, when open to air, was between 100 and 200 ml up to 7 Hz, then gradually decreased as the frequency increased. A Wright respirometer appeared to measure the volume flow fairly accurately up to 14 Hz. The pressure output against a closed volume of 1.1 liters achieved a maximum of 29 mmHg at 7 Hz. It gradually decreased as the frequency was changed from 7 Hz. The loudspeaker worked in such a way that the volume output decreased considerably when it was forced to move against a closed space to generate pressure. Adequate ventilation was achieved in all dogs from 1.4 to 10 Hz. At 14 Hz, the results were variable, and at 20 Hz and above, gross hypoventilation always resulted. The PaO2 values were always over 440 mmHg when 0.8 liter/(kg . min) of oxygen was supplied into the respiratory circuit. A speaker ventilator has the advantage of easy assembly and the possibility of applying various flows by electrical control. Its disadvantages are a lack of power and the difficulty in establishing ventilatory volumes without actual measurement.

Animals↗
PubMed2002

Pharmacokinetics, excretion, and mass balance of liposomal amphotericin B (AmBisome) and amphotericin B deoxycholate in humans.

The pharmacokinetics, excretion, and mass balance of liposomal amphotericin B (AmBisome) (liposomal AMB) and the conventional formulation, AMB deoxycholate (AMB-DOC), were compared in a phase IV, open-label, parallel study in healthy volunteers. After a single 2-h infusion of 2 mg of liposomal AMB/kg of body weight or 0.6 mg of AMB-DOC/kg, plasma, urine, and feces were collected for 168 h. The concentrations of AMB were determined by liquid chromatography tandem mass spectrometry (plasma, urine, feces) or high-performance liquid chromatography (HPLC) (plasma). Infusion-related side effects similar to those reported in patients, including nausea and back pain, were observed in both groups. Both formulations had triphasic plasma profiles with long terminal half-lives (liposomal AMB, 152 +/- 116 h; AMB-DOC, 127 +/- 30 h), but plasma concentrations were higher (P < 0.01) after administration of liposomal AMB (maximum concentration of drug in serum [C(max)], 22.9 +/- 10 microg/ml) than those of AMB-DOC (Cmax, 1.4 +/- 0.2 microg/ml). Liposomal AMB had a central compartment volume close to that of plasma (50 +/- 19 ml/kg) and a volume of distribution at steady state (Vss) (774 +/- 550 ml/kg) smaller than the Vss of AMB-DOC (1,807 +/- 239 ml/kg) (P < 0.01). Total clearances were similar (approximately 10 ml hr(-1) kg(-1)), but renal and fecal clearances of liposomal AMB were 10-fold lower than those of AMB-DOC (P < 0.01). Two-thirds of the AMB-DOC was excreted unchanged in the urine (20.6%) and feces (42.5%) with >90% accounted for in mass balance calculations at 1 week, suggesting that metabolism plays at most a minor role in AMB elimination. In contrast, <10% of the liposomal AMB was excreted unchanged. No metabolites were observed by HPLC or mass spectrometry. In comparison to AMB-DOC, liposomal AMB produced higher plasma exposures and lower volumes of distribution and markedly decreased the excretion of unchanged drug in urine and feces. Thus, liposomal AMB significantly alters the excretion and mass balance of AMB. The ability of liposomes to sequester drugs in circulating liposomes and within deep tissue compartments may account for these differences.

Adult↗
PubMed1990

[The lung in heart diseases].

The effects of "hypocirculation" and "hypercirculation" of the lungs are small. Hypocirculation has an influence of the ventilation/perfusion ratio, and can thus contribute to hypocapnia. In the early stages, hypercirculation--in particular via a left-to-right shung, leads to an increase in diffusion capacity; after a course of many years, a "counter-situation" occurs. Progressive pulmonary hypertension, as is exemplified for mitral stenosis, leads to measurable restrictive and obstructive impairment of function, and possible to unspecific hyper-reaction, as also, over the long-term, to a diminishement in membrane diffusion capacity. Chronic left heart failure is characterised by interstitial oedema at the level of the alveolar and bronchial capillary beds. The results are measurable restrictions in the static volumes, and in particular of the obstruction parameters and the closing volume that involve the small airways. In the individual case, no statement as to the extent of left heart failure is possible. In the passive pulmonary hypertension phase, diffusion capacity increases; in the further course of the disease, with development of interstitial and alveolar oedema, it decreases again. In acute left heart failure, the persistance and/or extent of pulmonary oedema is not determined solely by the magnitude of the pulmonary venous pressure. Permeability oedema--brought about by mediators--would appear to be significant on the basis of animal experiments. Not infrequently, left cardiac failure leads to small pleural effusions which occur in combination with substantial atelectasia, the aetiology of which is unclear. Interpretation difficulties are caused by the clinical findings and function-analytical data obtained in patients with a combination of chronic lung disease and reducted volume storage capacity of the pulmonary circulation and of the left heart failure, a common situation in the elderly patient. Diminished pulmonary function parameters that fail to adequate respond to bronchodilators may be an expression of left ventricular failure.

Heart Failure↗
PubMed1984

[Obstruction of the peripheral airways : clinical aspects, radiological picture, therapeutic impact].

Peripheral airways obstruction (PAO) is a pathophysiologic syndrome combining normal values of the usual tests (one-second forced expiratory volume, airway resistance) and abnormalities of "sensitive" tests (dynamic compliance, closing volume, forced expiratory flows, response to helium-oxygen mixtures). Clinical data are scarce, and the radiological aspects nonspecific. The natural history of the PAO is not fully understood. Therapeutic measures could be useful, but their efficacy was not yet systematically evaluated. From the theoretic point of view, the notion of bronchiolar obstruction is important in as much as it represents the initial phase of any obstructive process. In practice, the detection of a PAO identifies the "at risk" subject allowing the application of efficient preventive measures.

Humans↗
PubMed1980

Chronic airways obstruction in pulmonary sarcoidosis: its poor response to bronchodilators.

Emphysema, chronic bronchitis, asthma, and cystic fibrosis are often cited as examples of chronic airways obstruction, while sarcoidosis is typically restrictive. Approximately 15 percent of sarcoidosis patients, however, have airways obstruction clinically characterized by wheezing with granulomatous involvement of airways. Since the majority have Stage IV disease by chest radiograph, their lungs usually have honey-combining with pulmonary fibrosis, adhesions, cavities, and mediastinal distortion.Patients had a mixed ventilatory defect, but obstruction of large airways was present as shown by decreased specific airways conductances. Small airways obstruction was also present as shown by low instantaneous flows at the terminal portion of the maximum expiratory flow-volume curve and diminished helium response of this curve. The closing volume, however, was not very sensitive. Radioactive xenon washout from ventilation lung scans and N2 washout from the lungs were prolonged in patients with worse disease.The authors conclude that the obstructive type of physiologic pattern is more frequent than recognized in sarcoidosis, which like that of cystic fibrosis has some restrictive element and is characterized by poor reversibility to bronchodilators. A trial period of beclomethasone dipropionate aerosol was not helpful in two patients. Relief of this distressing airways obstruction continues to pose a challenging problem in management.

Adult↗
PubMed1978

Even distribution of 133Xe bolus inhaled at residual volume in healthy subjects.

We selected from among 46 healthy students (22 to 31-yr-old) 7 subjects (group A) in whom the normalized height of phase IV (height of phase IV/phase IIIx100), after inhaling a bolus of He at RV, was very small (10%). We compared them with 6 subjects (group B) selected on the basis of a tall phase IV (78%, A vs. P P less than 0.005). Age and height were comparable, but weight was lower (P less than 0.05) and RV/TLC ratio (but not other spirographic indices) was larger (P less than 0.025) in group A. The average amplitude of cardiac oscillations was 4 times higher in group B (P less than 0.005). He closing volume, but not closing capacity was less in group A (P less than 0.05). A bolus of 133Xe inhaled at RV was nearly uniformly distributed in group A while producing a large vertical gradient in group B. The difference between groups A and B may reflect a difference in the mechanical properties of the chest wall leading to a less complete empting of the lung in the former group.

Adult↗
PubMed1990

Pulmonary mechanical function and diffusion capacity after deep saturation dives.

To assess the effects of deep saturation dives on pulmonary function, static and dynamic lung volumes, transfer factor for carbon monoxide (T1CO), delta-N2, and closing volume (CV) were measured before and after eight saturation dives to pressures of 3.1-4.6 MPa. The atmospheres were helium-oxygen mixtures with partial pressures of oxygen of 40-60 kPa. The durations of the dives were 14-30 days. Mean rate of decompression was 10.5-13.5 kPa/hour. A total of 43 divers were examined, six of whom took part in two dives, the others in one only. Dynamic lung volumes did not change significantly but total lung capacity (TLC) increased significantly by 4.3% and residual volume (RV) by 14.8% (p less than 0.05). CV was increased by 16.7% (p less than 0.01). The T1CO was reduced from 13.0 +/- 1.6 to 11.8 +/- 1.7 mmol/min/kPa (p less than 0.01) when corrected to a haemoglobin concentration of 146 g/l. Effective alveolar volume was unchanged. The increase in TLC and decrease in T1CO were correlated (r = -0.574, p less than 0.02). A control examination of 38 of the divers four to six weeks after the dives showed a partial normalisation of the changes. The increase in TLC, RV, and CV, and the decrease in T1CO, could be explained by a loss of pulmonary elastic tissue caused by inflammatory reactions induced by oxygen toxicity or venous gas emboli.

Adult↗
PubMed1995

Effect of weight loss and body position on pulmonary function and gas exchange abnormalities in morbid obesity.

OBJECTIVE: To determine, whether behavioral management of obesity including very-low-calorie-diet would produce weight loss enough to improve pulmonary mechanics and gas exchange in morbid obesity. DESIGN: Pulmonary function and arterial oxygenation were studied before and after weight loss in 11 patients attending a group therapy with the program of VLCD for 6 weeks and 16 weeks' behavioral intervention. MEASUREMENTS: Spirometry, diffusing capacity, body plethysmograph, closing volume and arterial blood gas analyses. RESULTS: The mean initial BMI was 45.4 kg/m2 (range 39.8-58.7 kg/m2) and decreased to 39.4 kg/m2 (range 31-49.8 kg/m2) (P < 0.01). Expiratory reserve volume (ERV) and functional residual capacity (FRC) improved significantly with weight loss. Closing capacity (CC) exceeded FRC in 10 cases of 11 at the initial stage, but after weight loss only in three patients. The mean arterial oxygen tension with the patients in supine position did not change after weight loss, but standing up improved PaO2 significantly before and after weight loss. CONCLUSION: The dietary treatment of morbid obesity was sufficient to induce improvement in lung volumes, but not enough to improve arterial oxygenation, although ventilatory mechanics was improved significantly and the tendency to early small airway closure was decreased. Hypoxemia was significantly relieved by standing up both before and after weight loss.

Adult↗
PubMed1988

Assessment of aortic pressure-volume relationships with an impedance catheter.

Volume measurements obtained with an impedance catheter (impedance volume measurements) have been used previously in determining pressure-volume relationships in the right and left ventricles and in the right atrium. The purpose of the present study was to determine the utility of impedance volume techniques in the assessment of aortic pressure-volume relationships in animals and humans. Experiments to develop this methodology were first performed in ten anesthetized dogs, with simultaneous measurements of aortic pressure (micromanometer), diameter (ultrasonic crystals), and impedance volume. Transient (20 sec) inferior vena cava (IVC) occlusion and nitroprusside infusion resulted in a reproducible series of aortic pressure-volume and pressure-diameter points. In each case changes in impedance volume closely paralleled changes in diameter. From the wide range of pressure-volume points, it was possible to construct pressure-volume plots for a single cardiac cycle, as well as longer loops over a 20-40 mm Hg pressure range. End-systolic and end-diastolic pressure-volume points could subsequently be identified, which outlined a more precise pressure-volume relationship that was linear in six cases and curvilinear in four cases, depending on the level of aortic pressure. We extended these techniques to human subjects undergoing diagnostic cardiac catheterization. Studies using the impedance catheter in the aorta were performed in 11 patients. Aortic pressure-volume curves were elicited during Valsalva maneuver to obtain data over a range wider than that of a single cardiac cycle. Measurements of relative volume were calibrated with simultaneous M-mode echocardiography in three patients. We conclude that pressure-volume relationships in the aorta can be assessed with impedance volume techniques, making possible in vivo measurements of arterial compliance. Potential nonlinearities in aortic P-V relationships require that the assessment of aortic compliance encompass as much as possible of the physiologic range of pressure and volume.

Animals↗
PubMed1976

The forced expiratory time as a measure of small airway resistance.

1. In five subjects, ten consecutive forced expiratory spirograms were recorded on each of 6 different days and the total forced expiratory time (FET) on each spirogram was measured. The mean overall coefficient of variation of the FET was 11.3% and of the ratio forced vital capacity (FVC)/FET was 8%. 2. Twenty-two subjects with probable small (less than 2 mm diameter) airway dysfunction as manifested by a reduced (less than 75% predicted) maximum mid-expiratory flow (MMEF) in the middle 50% of the FVC with normal FVC and FEV1 (greater than 80% predicted) were studied before and after bronchodilatation. There was no significant correlation between change in FET and change in MMEF (r = 0.36, P greater than 0.01), but between change in MMEF (deltaMMEF) and change in FVC/FET (deltaFVC/FET) there was a positive correlation (r = 0.78, P less than 0.001). 3. In six of these twenty-two subjects, the deltaFVC/FET and deltaMMEF on bronchodilatation correlated well with the change in residual volume (deltaRV). but neither measurement correlated well with the change in the 'closing volume' measurement expressed as the ratio of phase 4/VC(%). The deltaFET did not correlate well with either deltaRV or delta[phase 4/VC(%)]. 4. In eighty-one selected normal subjects (FVC, FEV1 and MMEF all greater than 80% predicted) there was better correlation of age with the FVC/FET (r = -0.676) than with the FET (r = +0.43); both correlations were significant (P less than 0.001). 5. These results do not support the use of the FET as a suitable test of small airway function; however, the mean flow rate expressed as FVC/FET may, in the presence of a normal FEV1/FVC ratio, be an adequate test of small airway function.

Adult↗