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At least 271 records · Page 15Linked to original sources
PubMed1989

[Variability of respiratory function variables in healthy aged men].

We studied six healthy young males (young group; mean age 30.0 +/- SD 1.8 years, FVC 4.5 +/- 80.45 l and FEV1.0/FVC 87.6 +/- 4.3%), and five aged healthy males (aged group; age 63.8 +/- 3.0 years, FVC 3.40 +/- 0.22 l and FEV1.0/FVC 75.9 +/- 3.2%) to evaluate the variability of pulmonary function. We measured flow-volume curves, closing volumes, functional residual capacities (FRC) and airway resistances (Raw) five times in different days in each person. The coefficients of variation in FVC and FEV1.0 in both groups were less than 5%, and there were no significant differences in these coefficients between the two groups. Although the coefficients in FEV1.0/FVC in both group were less than 5%, there was a significant difference between the two groups. The coefficients in flow at 50% FVC (V50), maximal midexpiratory flow (MMF) and peak expiratory flow rate (PEFR) in the aged group were significantly larger than those in the young group. The coefficients in closing volume, FRC, Raw and specific airway conductance (SGaw) using body plethysmography exceeded 10% in both groups, and the coefficients in Raw and SGaw in the aged group were significantly larger than those in the young group. These results suggest that aging worsens the variabilities of respiratory function in FEV1.0/FVC, MMF, V50, Raw and SGaw.

Adult↗
PubMed1977

Detection of acute effects of cigarette smoking on airway dynamics: A critical and comparative study of pulmonary function tests.

In an effort to determine which measure of airway dynamics was the most sensitive to airway obstruction, comparisons were made between a variety of tests. Twenty cigarette smokers were studied both before and immediately after smoking a cigarette. The maximum midexpiratory flow (FEV25-75) and the FEV1/FVC per cent were abnormal in the largest number of cases. Closing volume was abnormal in only one case. Significant worsening in function after smoking a cigarette occurred in airway resistance and specific conductance. A lesser degree of impairment in airway dynamics was evident from FEV25-75 and first-second expired volume. The closing volume showed no change.

Adult↗
PubMed1975

Reversibility of pulmonary function abnormalities in smokers. A prospective study of early diagnostic tests of small airways disease.

A prospective study of the reversibility of pulmonary function abnormalities in cigarette smokers was performed. Base line studies of 50 otherwise healthy cigarett smokers included lung volumes, static volume-pressure curves, closing volume, slope of phase III and maximum expiratory flow-volume curves while the subjects breathed air and while they breathed an 80 per cent helium-20 per cent oxygen mixture (He). Ten subjects, seven women and three men, ages 29 to 61, were restudied 6 to 14 weeks after they had stopped smoking. Two of these people had an abnormal closing volume, four had an abnormal slope of phase III and five had an abnormal response to helium. Static volume-pressure curves, slope of phase III and airflow rates were not improved on the repeat studies. There was increases in maximum expiratory flow rates with He at 50 and 25 per cent of vital capacity, reductions in the lung volume at which the maximum expiratory flow rate of air and He became identical, and decreases in closing volume. These reversible functional changes in smokers are thought to indicate improvement of peripheral airways obstruction.

Adult↗
PubMedDate not supplied

Small airways disease in coal miners. A longitudinal study.

Seventeen of an original cohort of 25 non-smoking working coal miners and 6 age-matched controls studied in 1969 were re-examined in 1973. Measurements included lung volumes, maximal expiratory flow-volume curves, and closing volumes. Miners, when compared with controls, showed a marked decline in maximal expiratory flow at mid-vital capacity (V 50%) over the 4-year period which took place without significant change in the 1-second forced expiratory volume (FEV1). Frequency dependence of dynamic compliance (Cdyn) in association with an increased upstream airways resistance (Rus), and also loss of lung elastic recoil (PL(St)) which were present at the time of the original study led to similar declines in V 50%. An abnormally elevated closing capacity expressed as a percentage of total lung capacity (CC/TLC)% was found in 9 miners (53%) and none of the controls. Closing volume as a percentage of vital capacity (CV/VC)% was abnormal in 4 miners (23.5)% and no controls. Measurement of closing volume did not relate well to the variety of mechanical abnormality present on the original study; namely, loss of recoil or small airways obstruction. The presence of an elevated (CC/TLC)% and (CV/VC)% correlated mainly with the presence of hyperinflation as indicated by an elevated residual volume.

Follow-Up Studies↗
PubMed1986

A comparative in vitro study of the closing characteristics of Björk-Shiley and Bicer-Val tilting disc mitral valve prostheses.

The replacement of mitral valves has become a relatively common procedure in cardiac surgery. Information concerning losses due to backflow through the valve may be used to assess and compare the physical characteristics of commercially available prostheses. A simple apparatus based on an artificial ventricle was used to measure closing volume, leakage volume, total volume, leakage rate and closing time on a beat by beat basis for Björk-Shiley and Bicer Val prosthetic mitral valves. The Björk-Shiley valve opened to 60 degrees and displayed a smaller closing volume than the Bicer Val, which opened to 75 degrees; and the Björk-Shiley displayed higher leakage than the Bicer Val, thus reducing its advantage in terms of closing volume. Overall, the Bicer-Val showed about 1 ml greater reflux per beat than the Björk-Shiley. Study of a Bicer-Val, modified to have an opening angle of 80 degrees, confirmed that valve closing volume was a function of opening angle.

Cardiac Output↗
PubMedDate not supplied

Effect of hyperbaric oxygen therapy on some basic vital functions.

The purpose of this work was to investigate the effect of hyperbaric oxygen therapy (HOT) on the respiratory system and cardiovascular system in patients with ischaemia of lower extremities exposed repeatedly to hyperbaric oxygen for therapeutic reasons. Oxygen pressure of 2.4 ATA was used, the duration of exposure to 100% oxygen was 90 min on the average. Hyperbaric oxygen was applied every 2-3 days during 1 to 3 months. During the treatment airway resistance, pulmonary elastance, respiratory rate, respiratory volume, intraoesophageal pressure, closing volume and vital capacity were determined. Changes of heart rate caused by this treatment were recorded as well. A statistically significant increase of airway resistance, increased pulmonary elastance, decreased respiratory volume and respiratory rate, increased closing volume, decreased vital capacity and slowing down of heart rate were observed.

Adult↗
PubMed1978

Comparison of active and passive manoeuvres on the pattern of airway closure in man.

The effect of active and passive manoeuvres on closing volume was studied in conscious subjects. There were no significant differences in closing volume in nine of 10 non-smokers. There was a significantly greater closing volume with the passive manoeuvre (airway pressure +3 kPa to --2 kPa) in seven of nine smokers and one non-smoker with evidence of mild obstructive airway disease. The sensitivity of the closing volume to airway pressure could not be reproduced in three non-smokers exposed to a histamine aerosol. In two of three smokers the effect of airway pressure on closing volume was abolished by salbutamol. The results suggest that subjects with irritable airways may show an increase in closing volume with a change in airway pressure.

Adult↗
PubMed1976

Computer analysis of the single-breath nitrogen washout curve.

A computerized system has been developed to analyze the parameters that can be derived from the nitrogen washout curve. Analog signals for air flow, volume, and nitrogen concentration are entered either on-line or off-line into a 24,000 mini-computer. The program calculates vital capacity, total lung capacity, and residual volume, as well as the slope of phase III, closing volume in liters, total lung capacity, residual volume, closing capacity, closing volume/vital capacity ratio, and closing capacity/total lung capacity ratio. Validation tests showed excellent correlation between hand- and computer-calculated values of closing volume(r=0.864), vital capacity (r=0.997), total lung capacity (r=0.991), and slope of phase III (R=0.926). We concluded that the computerized system for analysis of the expired nitrogen washout curve is as reliable as hand calculations and is immeasurably faster.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Arterial hypoxemia in patients with hepatic cirrhosis.

Pulmonary function tests were studied in 105 patients with cirrhosis of the liver who had no clinical or radiographical evidence of cardiopulmonary disease. Spirometric data such as VC, FRC, RV, TLC, RV/TLC and FEV1.0% were within normal limits in all subjects. However, flow-volume curve and closing volume curve were abnormal in the majority. In flow-volume curve, V25, was decreased and the V50/V25 value was increased; on the other hand, closing volume was markedly increased and FRC-CC value was reduced in the patients with hepatic cirrhosis. The closing capacity tended to exceed the FRC in the patients with arterial hypoxemia, indicating the presence of airway closure and gas trapping during resting ventilation. Therefore, ventilation-perfusion imbalance may be an important cause of arterial hypoxemia in patients with cirrhosis of the liver.

Adult↗
PubMed1980

The mechanism of arterial hypoxia occurring in acute pancreatitis.

Respiratory Function has been measured in 14 patients with acute pancreatitis, none of whom has a previous history of cardiac or respiratory disease. Their mean age was 40 years, mean PaO2 on admission, 11 kPa, and all had normal chest radiographs at that time. Arterial hypoxia was a common development and the mean PaO2 at the time of most severe hypoxia was 8.6 kPa with the lowest individual recording 4.9 kPa. In addition to daily arterial blood gas monitoring, dynamic ventilatory tests and measurements of lung volume, transfer factor, closing volume, right to left shunts and studies of gas exchange were performed. Gas exchange and shunt measurements indicated that the major abnormality responsible for arterial hypoxia was right to left shunting. Seven patients developed radiological abnormalities, five of whom has pleural effusions. Five patients showed a mild restriction in lung volume but there were no major consistent abnormalities of dynamic ventilatory tests, transfer factor, or closing volumes. Thus small airway closure, in dependent parts of the lung and less certainly loss of surfactant are unlikely to be major factors in the aetiology of arterial hypoxia in patients with acute pancreatitis. All measurements were repeated at least three months after the acute illness. The respiratory insufficiency which occurs in this disease is possibly another variant of the adult respiratory distress syndrome.

Acute Disease↗
PubMed1983

Breathing near to residual volume with positive expiratory pressure.

Breathing near to residual volume produces arterial desaturation demonstrable by ear oximetry. This paper describes the effect on arterial saturation measured by an ear oximeter of expiring to residual volume, taking a normal inspired volume of air from ambient pressure, and then expiring to residual volume against a pressure of 10-15 cm of water. This breathing pattern was continued for several minutes. Carbon dioxide output and oxygen consumption were measured during the study and the closing volume at ambient pressure was compared with that at increased expiratory pressure. Arterial desaturation was actually increased by the increased airways pressure, the increase being modified both by minute volume and tidal volume. Closing volume was only slightly increased, but residual volume was considerably increased, by the raised pressure. The desaturation is only partially explicable on a ventilatory basis, and there is probably a component concerned with perfusion, and the absence of perfusion adaptation from hypoxic areas does not appear to accord with current hypotheses.

Adult↗
PubMed1976

Xenon and nitrogen single-breath washout curves in patients with airway obstruction.

In patients with chronic obstructive lung disease, we determined single-breath N2 and 133 Xe washout curves, and regional distributions of volumes (Vr) and of 133Xe boluses inhaled at residual volume (VIRV). Patients suffering from emphysema with minimal airway obstruction demonstrated large closing volumes and apicobasal distribution gradients, apparently because of a steep pulmonary recoil pressure-volume curve. In one subject with basal small airway disease there was no vertical gradient in regional residual volume; closing volume was increased with the 133Xe technique but almost absent with the N2 technique. Patients with moderate-to-severe airway obstruction had upward-sloping alveolar plateaus without distinct phase IV, and small apicobasal differences in Vr and VIRV. The latter resulted probably from increased regional differences in time constants counteracting the influence of gravity. Finally, patients with severe airway obstruction and basal emphysema demonstrated a rising N2 but a descending 133Xe plateau; the gradient for VIRV was normal, and reversed for Vr. This pattern was attributed to nongravitational differences in time constants causing a first in-first out distribution.

Adolescent↗
PubMedDate not supplied

In vitro ultrasound characterization of a polyurethane trileaflet valve.

Polyurethane synthetic trileaflet valves were compared with commercial prostheses in vitro, in a pulse duplicator using ultrasound to characterize the flow velocities and patterns. Flow-pressure drop behavior was in the middle range of other prosthetic valves. Diastolic regurgitant jets were located by color Doppler ultrasound, and there appeared to be some leakage through the leaflet fold at the commissure. Nevertheless, the closing volumes and closed valve leakage volumes were, on average, lower than other prosthetic valves. Systolic 20 Hz spectral oscillations detected with pulsed Doppler and continuous wave Doppler were attributed to leaflet flutter in the open valve.

Aortic Valve↗
PubMed1987

Computerized single-breath nitrogen washout in children: variability and reproducibility.

The variability, short-term (1 hour) and long-term (2 weeks) reproducibility of the variables derived from the single-breath N2 test were evaluated in a group of 56 healthy children aged 10 to 16 years with a computerized system. The variability was low for vital capacity and total lung capacity (coefficient of variation less than 3%), moderate for residual volume and phase III N2 slope (9 and 13%) and very high for closing volume (more than 50%). A closing volume could not be identified by the computer algorithm in 18.3% of the trials. The reproducibility of the variables was satisfactory both at 1 hour and at 2 weeks, with the exception of the closing volume, whose increase at 2 weeks seemed to be due to methodological factors. We conclude that reliable results of static lung volumes and phase III N2 slope, but not of closing volume, may be obtained in children by a computerized system in epidemiological studies.

Adolescent↗
PubMed1975

Functional abnormalities in young asymptomatic smokers with special reference to flow volume curves breathing various gases.

Functional abnormalities have been described in healthy, asymptomatic young smokers. Fifteen subjects between 22 and 30 years of age, who smoked but were completely asymptomatic, were compared with 10 nonsmokers of the same age group using lung volumes, maximal expiratory flow rates, closing volumes, and maximal expiratory flow volume curves breathing air and a helium-oxygen mixture. Lower maximal mid-expiratory flow rates, higher closing volumes, and significant differences in flow volume curves with the helium-oxygen mixture were found in smokers. Special attention was given to the volume expressed as percentage of vital capacity at which the flows with air and the helium-oxygen mixture were equal for each subject ("equal-flow volume"). This volume was found to be significantly higher for smokers than nonsmokers. The authors offer explanations for these differences and suggest that smoking may alter compliance, as reflected by abnormal closing volumes, and resistance of the small airways as determined by differing responses in flow rates after helium-oxygen breathing at low volumes.

Adult↗
PubMed1976

Pattern of total and regional lung function in subjects with bronchoconstriction induced by 15-me PGF2 alpha.

Closing volume (single breath nitrogen test), regional ventilation and perfusion (using intravenous xenon-133), and total lung function (TLC, VC, and FEV) were measured before and after intramuscular administration of 250 mug 15-methyl prostaglandin F2alpha (15-me PGF2alpha) in 10 healthy women. The cardiac output was measured with the Minnesota impedance cardiograph model 304A and the transthoracic impedance was used as an expression of the thoracic fluid volume. The slope of the alveolar plateau on the closing volume tracing showed a 271% increase 20 minutes after the prostaglandin administration, at which time the closing volume per cent (CV%) had decreased (P less than 0-01) and the closing capacity (CC%) had increased (P less than 0-05). Vital capacity (VC) decreased (P less than 0-01), residual volume (RV) increased (P less than 0-01), and the total lung capacity (TLC) remained unchanged. The maximal decrease (9%) in FEV1 was seen after 20 minutes. All these measurements except the slope of the alveolar plateau returned to control levels after 60 minutes. The redistribution of regional ventilation was more pronounced than that of the regional pulmonary blood flow. No change was observed in cardiac output and transthoracic impedance. None of the patients experienced any dyspnoea. Our results are consistent with a more pronounced effect of prostaglandin F2alpha on the small airways (the alveolar plateau) than on the larger airways (FEV1). In cases where an increase in the slope of the alveolar plateau is observed, the closing volume per cent should not be used as a measurement of the lung disease. It is concluded that the single breath nitrogen test (N2 closing volume) is more sensitive than the conventional tests.

Bronchi↗
PubMed1975

Airway function in healthy subjects and patients with left heart disease.

1. In forty non-smoking healthy subjects and seventy-two patients with left heart diseases measurements were made of the volume expired in the first second of a forced expiration (FEV1) and the total volume expired in a forced expiration (FVC) before and after inhalation of salbutamol. Before and after salbutamol the healthy subjects and patients also inhaled maximally an inspirate, the first part of which contained 133Xe and, during controlled expiration, the radioactivity of the expirate was measured and plotted against its volume. the resulting curves were divided into phases of different slope by eye, the point at which phase 3 changed to phase 4 being nominated the closing volume. 2. In forty non-smoking healthy subjects inhalation of salbutamol was followed by significant increase in FEV1 but FVC and closing volume did not change. 3. Change in posture from seated erect to supine in thirty of these healthy subjects was accompanied by significant reduction in FEV1 and FVC and as closing volume was not significantly different in the two positions the ratio closing volume/vital capacity was increased with recumbency. 4. In seventy-two patients with left heart diseases without a history of cough or wheeze, FEV1, FVC, closing volume and the ratio closing volume/vital capacity were significantly different from values in the healthy subjects. There was no significant difference between non-smokers and ex-smokers amongst the patients. 5. Significant increase in FEV1, FVC and reduction in closing volume and the ratio closing volume/vital capacity followed inhalation of salbutamol in patients with heart diseases but the values remained significantly different from those recorded in the healthy subjects. 6. In twenty patients with heart diseases, FEV1 and FVC were reduced by change in posture from seated erect to supine but the ratio closing volume/vital capacity and the regression with age of this ratio were not significantly changed by change in position. 7. In patients with heart diseases the ratio closing volume/vital capacity was significantly correlated with severity of breathlessness and length of symptom-history but not with left ventricular end-diastolic or pulmonary vein wedge pressures.

Adult↗
PubMedDate not supplied

Effects of electric arc welding on ventilatory lung function.

Respiratory symptoms, spirometry, forced expiratory flows, and the nitrogen closing volume test were studied in 119 welders and 90 controls, matched with respect to age, height, and smoking habits. Respiratory symptoms according to a questionnaire were more prevalent in the welders. No short-term changes of the measured variables during the day or week attributable to welding were found in twenty-one nonsmoking welders. Compared to the controls, closing volume and closing capacity (i. e., closing volume + residual volume) were significantly higher, and total lung capacity and the amplitude of the cardiogenic oscillations in the nitrogen curve were significantly lower in the welders who were nonsmokers or exsmokers, whereas there were no differences among smokers. These findings in welders may be attributable to deposition of welding fume particles in peripheral small airways or alveoli.

Aerosols↗