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At least 469 records · Page 26Linked to original sources
PubMed1986

Reference values for lung function tests in men: regression equations with smoking variables.

Prediction formulas for static and dynamic spirometry, gas distribution, static lung mechanics and the transfer test were derived from measurements in healthy men. The measurements included total lung capacity, residual volume, airways resistance, static elastic recoil pressure of the lung, static compliance, closing volume, slope of the alveolar plateau (phase III), flow-volume variables (including mean transit time) during breathing of air or a helium/oxygen mixture, and conventional spirometric indices. The results from 146 smokers and 124 never-smokers were evaluated separately and combined. For all lung function tests a single regression equation was obtained. The prediction formulas included time-related smoking variables and were valid for both smokers and never-smokers. For many lung function tests, a nonlinear age coefficient resulted in a significant reduction in variance compared with simple linear models. Heavy tobacco smoking influenced most lung function tests less than ageing from 20 to 70 years, but for airways resistance, transfer factor and phase III the opposite was found.

Adult↗
PubMedDate not supplied

The effect of diffuse pulmonary fibrosis on lung mechanics.

Maximum expiratory flow-volume curves (MEFV), inflational and deflational pressure-volume curves, dynamic compliance at 20, 40, and 60 breaths per minute, closing volume (single-breath oxygen method), standard lung volumes are airway resistance measurements were made in eleven subjects with a clinical diagnosis of diffuse interstitial fibrosis (DIF) and eleven control subjects. No subject was a current cigarette smoker. Maximum flow-static recoil pressure curves (MFSR) were constructed and calculations of upstream resistance (Rus) were made. Comparison of the mean values showed no significant differences in airway resistance or FEV1/FVC% between the two groups; however, significant differences were noted in total lung capacity (TLC), forced expiratory volume in one second (FEV1) and expiratory flow rates. Nine of the diseased subjects had pressure-volume curves shifted to the right of the normal range, and a significant decrease in static expired and inspired compliance was noted in the diseased group. Six subjects with DIF showed increased Rus. The single-breath oxygen test results revealed an increased slope of phase III (delta N2/I) in the diseased group. Decreases in the static compliance may be explained by loss of lung volume in some patients with DIF. There is also evidence that the small airways may be affected by this disease process.

Adult↗
PubMed2001

In-vitro measurements of the regurgitation of mechanical mitral heart valve prostheses in case of atrial fibrillation.

BACKGROUND AND AIM OF THE STUDY: The characterization of heart valve prostheses requires regurgitation tests to be conducted in pulsatile flow. Although tests are generally conducted in accordance with hemodynamic conditions of a healthy young man, heart valve implantation is often associated with other pathology, such as atrial fibrillation. To run more realistic trials, four mechanical heart valve prostheses were tested with, and then without, atrial contraction. METHODS: The dual activation simulator (DAS) allow simulation of physiologically normal and pathological flows through the mitral valve. The DAS comprises silicon-based cavities, is activated by pumps, and was equipped successively with monoleaflet (Björk-Shiley, Medtronic Hall) and bileaflet (St. Jude Medical, CarboMedics) valves. Each valve (mitral, size 27 mm) was tested under two conditions (with and without atrial contraction) at a mean flow rate of 3 l/min of glycerol/water solution (analog blood viscosity). RESULTS: Leakage volumes were of the same magnitude as the precision of the instruments. Respectively, closing volumes increased from normal conditions to atrial fibrillation from 3.2 to 5.1 ml for Björk-Shiley, from 4.6 to 6.3 ml for Medtronic Hall, from 5 to 6.6 ml for St. Jude Medical, and from 5.2 to 5.4 ml for CarboMedics. The standard deviation was below the precision of measurements (+/- 0.5 ml). CONCLUSION: Without atrial contraction, the valves seemed to be closed by backward flow only, thus confirming earlier reports. This study showed that different heart valves behave differently in pathological situations with regard to their design; this must be considered when selecting a valve for implantation.

Atrial Fibrillation↗
PubMed1993

Pulmonary function one and four years after a deep saturation dive.

The pulmonary function of 24 Norwegian divers who had participated in a deep saturation dive to pressures of 3.1-4.6 MPa was reevaluated one and four years later. Twenty-eight divers performing ordinary saturation diving to pressures of 0.8-1.6 MPa and followed over a three-year period served as referents. A significant reduction in forced expiratory volume in 1 s (FEV1.0) of 210 (SD 84) ml (P < 0.001) occurred the first year after the dive. Thereafter the annual reduction in FEV1.0 was 28 (SD 62) ml.year-1; this value did not differ from the 35 (SD 80) ml.year-1 of the referents. The forced midexpiratory flow rate and forced expiratory flow rates at low lung volumes were also significantly reduced one year after the deep dive, and the closing volume was increased. No significant changes occurred in forced vital capacity. The results agree with those of cross-sectional studies on divers' lung function and indicate the development of airflow limitation in relation to diving exposure.

Adult↗
PubMed1983

The influence of ketotifen and aminophylline on the central and peripheral airways.

In a double-blind study we compared the effect of 2 mg ketotifen (Zaditen) daily and 1050 mg aminophylline daily for 6 months in two groups of altogether 24 patients with bronchial asthma and a chronic obstruction of the airways. Lung function tests were done in regular intervals to investigate the effects of the drugs on the central airways resistance, thoracic gas volume, forced expiratory volume of the first second and inspiratory vital capacity--and the peripheral airways closing volume, flow of iso and the flow volume curve. Ketotifen reduced the obstruction of the central and of the peripheral airways. Aminophylline showed a less pronounced effect on the obstruction of the central airways and did not influence the peripheral airways. Number and severity of asthmatic attacks, cough, dyspnea and expectoration improved with both drugs. From our results we conclude that ketotifen reduces the obstruction of the central airways and also may exert a direct influence on the small airways. This drug therefore seems to possess special antiasthmatic effects. In contrast aminophylline acts as a rapidly effective bronchodilating agent with no detectable effects on the peripheral airways.

Adult↗
PubMed1982

Respiratory changes after major burn injury.

In 32 major burn patients, routine respiratory measurements and blood gases analysis were performed. Striking differences were found between survivors and nonsurvivors in these variables. Marked increased in minute volume and respiratory rate were observed in nonsurvivors starting from the 6th day postburn, while PaCO2 increased with larger tidal and minute volumes. At the same time, PaO2 was lower than in survivors. In survivors, the closing volume, maximum mid-expiratory flow rate, and peak rate were lower than the predicted normal values. This may indicate that after major burn injury, ventilatory power decreased and some pathological changes occurred in small airways and alveoli without apparent pulmonary complications. Marked differences in the changes of respiratory rate and min volume between survivors and nonsurvivors may indicate the value of simple respiratory measurements for prediction of outcome in burn patients.

Adult↗
PubMed1991

Pulmonary function in men after oxygen breathing at 3.0 ATA for 3.5 h.

As a pulmonary component of Predictive Studies V, designed to determine O2 tolerance of multiple organs and systems in humans at 3.0-1.5 ATA, pulmonary function was evaluated at 1.0 ATA in 13 healthy men before and after O2 exposure at 3.0 ATA for 3.5 h. Measurements included flow-volume loops, spirometry, and airway resistance (Raw) (n = 12); CO diffusing capacity (n = 11); closing volumes (n = 6); and air vs. HeO2 forced vital capacity maneuvers (n = 5). Chest discomfort, cough, and dyspnea were experienced during exposure in mild degree by most subjects. Mean forced expiratory volume in 1 s (FEV1) and forced expiratory flow at 25-75% of vital capacity (FEF25-75) were significantly reduced postexposure by 5.9 and 11.8%, respectively, whereas forced vital capacity was not significantly changed. The average difference in maximum midexpiratory flow rates at 50% vital capacity on air and HeO2 was significantly reduced postexposure by 18%. Raw and CO diffusing capacity were not changed postexposure. The relatively large change in FEF25-75 compared with FEV1, the reduction in density dependence of flow, and the normal Raw postexposure are all consistent with flow limitation in peripheral airways as a major cause of the observed reduction in expiratory flow. Postexposure pulmonary function changes in one subject who convulsed at 3.0 h of exposure are compared with corresponding average changes in 12 subjects who did not convulse.

Adult↗
PubMed1989

Nitrogen dead space in heavy smokers aged 44-58 years.

Functional and alveolar dead spaces for nitrogen (VDF and VDalv) were calculated in a population of 20 male and 20 female heavy smokers and compared to data from static and forced spirometry (functional residual capacity [FRC], residual volume [RV], lung clearance index [LCI] and volume of trapped gas [VTG]) obtained with the same multiple-breath nitrogen wash-out as the dead spaces, and to variables considered sensitive to small airways disease measured with a single-breath nitrogen elimination (closing volume in per cent of vital capacity [CV%], closing capacity in per cent of total lung capacity [CC%] and slope index [SI]). Both nitrogen dead spaces increased with tidal volume in smokers as well as in healthy non-smokers. The majority of smokers were outside the predicted mean +2 SD for VTG (75%), CC and VDalv (70%) and SI (65%). The following variables were less sensitive for disclosing abnormality: CV (55%), RV (53%), LCI (38%) and forced expired volume in the first second (FEV1, 33%). If high sensitivity is considered preferable in epidemiological studies, the nitrogen dead spaces are equally as sensitive as the better of earlier described tests, and significantly superior to LCI and FEV1. Being tests that measure alveolar distribution of inhaled gas, they are probably sensitive to small airways disease.

Adult↗
PubMed1975

Anaesthesia for intestinal short circuiting in the morbidly obese with reference to the pathophysiology of gross obesity.

Sixteen extremely obese patients were anaesthetized for intestinal short circuiting operations. Severe obesity may cause pathological cardio-pulmonary changes. Cardiovascular alterations include increased systemic, pulmonary artery and pulmonary capillary venous pressure. Cardiac output, total blood volume and left ventricular work increase. Expiratory reserve volume and consequently functional residual capacity decrease with gross obesity. Functional residual capacity falls below closing volume and inspired gas may be distributed to non-dependent lung zones, resulting in decreased ventilation/perfusion ratios and arterial hypoxaemia. Low total respiratory compliance increases the oxygen cost of the work of breathing. Obesity may change the dose requirements for regional anaesthesia and long-acting muscle relaxants. General anaesthesia may also reduce functional residual capacity. We used a technique of anaesthesia which consisted of epidural analgesia with intra-operative mechanical ventilation and which specifically avoided volatile inhalation agents and long-acting muscle relaxants. All patients were extubated immediately after operation and returned to the recovery room for an average duration of 26 hours. Post-operative treatment included humidified oxygen, chest physiotherapy and elevation of the head of the bed to 45 degrees. Each patient's respiratory progress was monitored by repeated determinations of arterial blood gases and vital capacity and by serial chest X-rays. None of the patients in this group required post-operative tracheal intubation and mechanical ventilation.

Anesthesia, Epidural↗
PubMed1982

Changes in lung function after smoking cessation: an assessment from a cross-sectional survey.

Cross-sectional lung function data of 51 ex-smokers (mean, 8 +/- 7 yr since smoking cessation) were compared with those of 54 nonsmokers and 105 current smokers. All subjects were steel workers 45 to 55 yr of age. In order to assess whether lung function indexes improve after smoking cessation, "expected" values were calculated for the ex-smokers, taking into account both duration of smoking and time since cessation. Observed values of forced expiratory volume in one second, vital capacity, residual volume, peak expiratory flow rate, slope of the N2 single-breath washout, and bolus closing volume were significantly different from "expected" ones. This suggested that smoking cessation not only stopped the smoking-induced fast decline in lung function, but even led to some reversal toward nonsmoking values. This was already apparent in 22 subjects who had quit smoking less than 5 yr previously.

Cross-Sectional Studies↗
PubMed1985

Effects of pulmonary hemodynamics on lung function in adult patients with atrial septal defect.

To clarify the relationship of pulmonary function with differing severity of atrial septal defect (ASD) and to assess the effects of pulmonary hemodynamics on these functions, we classified 101 patients with adult ASD by their pulmonary arterial mean pressure (PAm) and pulmonary blood flow (Qp), and compared details of pulmonary functions between pairs of groups. Classification was by drawing lines at the PAm of 20 mmHg and the Qp of 10 L/min. Group I was the low pressure-low flow group, Group II the low pressure-high flow group, Group III the high pressure-low flow group, and Group IV the high pressure-high flow group. Vital capacity as the percentage of predicted (%VC) was low in Groups III and IV. There were no significant differences in the ratio of forced expiratory volume in one second to forced vital capacity (FEV1%), flow at 25% forced vital capacity and closing volume as the percentage of predicted (%V25, %CV/VC) between each group. Both maximum midexpiratory flow rate and flow rate at 50% forced vital capacity as the percentage of predicted (%MMEF, %V50) in Group III with the most severe ASD, were significantly low. Pulmonary diffusing capacities for carbon monoxide as the percentage of predicted (%DLco) exceeded 100% in all groups, and tended to decrease with increases of PAm without relation to Qp. Pulmonary dysfunctions in adult ASD were mainly due to restrictive changes accompanied by obstructive change in proportion to the decrease of VC. Peripheral airway obstructions are mild in ASD and these might be caused by lower pressure of left atrium and no existence of pulmonary venous congestion in ASD, even in the most severe group.

Adolescent↗
PubMed1995

Effects of venous gas microemboli on pulmonary gas transfer function.

Dynamic lung volumes and flows, slope of phase III of the single breath oxygen test (delta-N2), closing volume (CV), and transfer factor for carbon monoxide (TICO) were measured before and 1 h after an air dive in a hyperbaric chamber to a pressure of 0.49 MPa for 40 min. Six divers had a bottom time of 20 min and a rate of decompression of 50 kPa x min-1, and six divers had a bottom time of 24 min and a rate of decompression of 100 kPa x min-1. Decompression stops were 5 min at 0.16 MPa and 10 min at 0.13 MPa for both groups. As control exposure they were breathing O2 at atmospheric pressure for 40 min. The dive and control exposure were done on different days within 1 wk, in random order. Doppler ultrasound monitoring for venous gas microemboli (VGM) was done during the first hour after the dive. VGM were detectable in all six divers with the fast decompression rate and in one subject with the slow rate (P < 0.01). In the subjects having VGM there was a significant reduction in TICO of -5.9 +/- 4.4% compared with -0.5 +/- 3.4% after the control exposure (P = 0.034). In the five subjects without detectable VGM, the changes in TICO were -2.8 +/- 3.7% and 0.2 +/- 3.8%, respectively. There were no significant changes in dynamic lung volumes and flows, CV, or delta-N2. A reduction in TICO may reflect effects of VGM after dives in which the effect of O2 exposure is negligible.

Adult↗
PubMedDate not supplied

Exposure to formaldehyde: effects on pulmonary function.

Forty-seven subjects exposed to formaldehyde (mean air concentration 0.45 mg/m3) and 20 unexposed subjects, all of whom were employed at a carpentry shop, were studied with regard to symptoms and pulmonary function. Symptoms involving eyes and throat as well as chest oppression were significantly more common in the exposed subjects than in the unexposed controls. Spirometry and single breath nitrogen washout were normal Monday morning before exposure to formaldehyde. A reduction in forced expiratory volume in 1 sec by an average of 0.2 L (P = .002), percent forced expiratory volume by 2% (P = .04), maximum midexpiratory flow by 0.3 L/sec (P = .04) and an increase in closing volume in percentage of vital capacity by 3.4% (P - .002) were seen after a day of work and exposure to formaldehyde, suggesting bronchoconstriction. Smokers and nonsmokers displayed similar changes in spirometry and nitrogen washout.

Adult↗
PubMedDate not supplied

Tests of minimal obstruction in the small airways: interrelationships and physiologic significance.

Several technics have become popular to detect airway obstruction in the small (less than 2 mm diameter) peripheral bronchi which appear to be the site of the early lesions in chronic obstructive pulmonary disease (COPD). These include determining maximal midexpiratory flow rate (MMFR) from the expiration spirogram, maximum expiratory flows at low lung volumes from the maximum expiratory flow-volume (MEFV) curve, a comparison of flow-volume curves during air and helium/O2 breathing, demonstration of frequency dependence of compliance, and the measurement of closing volume (CV). This discussion attempts to interpret the literature relative to these tests, examining their physiologic basis and clinical significance while relating them to the standard spirometric tests. The aim is to provide the clinical anesthesiologist with a better understanding of the information they provide, since their physiologic basis relates well to the many aspects of abnormal lung function which appear during anesthesia and the entire perioperative period.

Airway Obstruction↗
PubMedDate not supplied

Lung transfer factor for carbon monoxide measured during a slow single breath without breath-holding and during slow exhalation.

We considered whether a slow single breath with neither breath-holding nor carefully controlled flows could provide estimates of lung transfer factor for CO (TLCO) similar to those obtained with the usual standardized single breath technique. This technique requires actual flow rates and volume variations to be taken into account [10], as well as the use of a fast CO analyser and computerized calculations. TLCO values found with this method (TLCOsb) for 5 normal subjects and 29 patients with various respiratory diseases did not differ from those obtained with the standardized test (p less than 0.001). TLCO was also measured during exhalation only, by the use of a single compartment, constant TLCO equation and a computational procedure which provided a mean TLCO value for a given expired volume range (TLCOex). A unique TLCOex was sufficient to account for the whole exhalation in normal subjects and certain patients. In most patients two TLCOex were necessary, one for large lung volume after dead space washout and the other one accounting for the second half of expiration until closing volume. Most TLCOex were larger than TLCOsb calculated during the same slow breath. This over-estimation was found to be correlated (p less than 0.001) with the phase III argon slope. In patients where two TLCOex values were required to describe the exhaled CO course, we found that TLCOex decreased with lung volume. This decrease was also correlated with the argon slope (p less than 0.001). The observed difference between TLCOsb and TLCOex values and the decrease of TLCOex with lung volume probably reflect inhomogeneous ventilation distribution.

Adult↗
PubMed1997

Small airway closure and positive end-expiratory pressure in mechanically ventilated patients with chronic obstructive pulmonary disease.

The effects of positive end-expiratory pressure (PEEP) on alveolar recruitment and closing volume were studied in ten supine, sedated, and paralyzed patients with chronic obstructive respiratory disease and acute respiratory failure. We applied PEEP (0, 5, 10, and 15 cm H2O) and constructed inflation static volume-pressure (V-P) curves. In all patients, the static V-P curves obtained at different PEEP levels were superimposed on each other, indicating that with PEEP there was no recruitment of previously atelectatic lung units. However, the static V-P curves exhibited an inflection point, which should reflect the critical pressure (Po) required to reopen all closed airways, whilst the corresponding lung volume (Vo) reflects the opening volume. On average, Vo was 0.71 L above the relaxation volume of the respiratory system (Vr). All patients, however, exhibited dynamic hyperinflation, i.e., with zero PEEP (ZEEP) the end-expiratory lung volume (EELV) was 0.54 L above Vr. Nevertheless, in seven patients the EELV on ZEEP was below Vo, resulting in cyclic reopening and closure of small airways with each breathing cycle, with concomitant mechanical stresses on the peripheral airways that may lead to low-volume barotrauma. Such barotrauma may be prevented by increasing with PEEP the EELV to Vo.

Acute Disease↗
PubMed2002

Role of lipid membrane-nucleic acid interactions, DNA-membrane contacts and metal (II) cations in origination of initial cells and in evolution of prokaryotes to eukaryotes.

The problems of the origin of primary cells and eukaryotic cells are discussed in terms of possible role of interactions between nucleic acids with lipid membrane according to corresponding original hypothesis. We propose that there are two main hypotheses of the origin of primary cells: (a). RNA appeared before proteins and DNA [Nature 213 (1967) 119]; (b). it is needed for the appearance of a primary cell, the volume closed by the lipid membrane. There was no information about the ways on how RNA appeared inside that volume for saving the reaction products around. Our hypothesis suggests that one of the starting points in the origination of primary cells was the interaction of nucleic acid and lipid membrane bubbles in the presence of metal (II) ions (which existed in high concentrations in prebiotic conditions), and this resulted in the enclosing of the pro-RNAs inside the lipid membrane. This hypothesis is formulated by us on the basis of experimental biochemical and biophysical studies of the DNA/RNA-phospholipid vesicles interactions in the presence of metal ions (II) fulfilled in the Institute of Biomedical Chemistry, RAMS, Moscow and Institute of Biophysics, RAS, Pushchino. Our belief is that DNA-membrane contacts (DNA-MCs) played an important role in the prokaryotes-to-eukaryotes transition. The model of the confluence of four prokaryotic cells may explain the prokaryotes-to-eukaryotes transition by the way of eukaryotic nuclear pore formation from prokaryotic Bayer' contacts. The main requirement for the following fusion of prokaryotic cells must be their mutual orientation. After possible association, the division of the formed cell is begun. The great advantage of the model of four prokaryotic cells is the profit in the metabolism and the possibility of the intensive growth of intercellular membrane structures.

Animals↗
PubMed1979

Absence of effects of hypoxia on small airway function in humans.

We measured the effects of sustained isocapnic hypoxia (PAO2 = 40--50 Torr; PACO2 = 38--42 Torr) on tests sensitive to small airway function in healthy human subjects. Maximum expiratory flow-volume curves on air, nitrogen-hypoxic, helium-normoxic, and helium-hypoxic mixtures as well as closing volumes while subjects breathed air and a hypoxic mixture were obtained. We then measured total lung capacity (TLC), both plethysmographically and by inert gas dilution, and used the nonplethysmographic method to measure the effects of hypoxia on TLC. In none of these tests were there any statistically significant changes when values obtained during hypoxia were compared with those during normoxia. It is suggested that previous reports that indicated that TLC was increased by hypoxia might have arisen from a plethysmographic artifact.

Adult↗