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Biomedical subjects

R Peslin

Publications and source records attributed to R Peslin.

At least 145 records · Page 8Linked to original sources
PubMed1979

Comparison of various methods for reading maximal expiratory flow-volume curves.

To determine the best procedure for reading maximal expiratory flow-volume curves 2 sets of 5 curves were obtained one hour apart in 89 subjects and processed digitally according to 8 different methods. Four indices were considered: the forced expiratory flows at 25, 50, and 75 per cent of the forced vital capacity, and the maximal mid-expiratory flow. When selecting the curve yielding the largest forced vital capacity or the largest sum of forced vital capacity and forced expiratory volume in 1 sec, flow values were significantly lower (P less than 0.001) and were often less reproducible than those obtained with most of the other methods. Computing the mean of the indices among the curves with the 2 largest forced vital capacities also provided comparatively low values, but with with better reproducibility. In contrast, maximal flows were probably overestimated by using the highest values among the curves having forced vital capacity or a surface area within 5 per cent of the largest, or when reading the indices on a composite curve obtained by superimposing individual breaths at residual volume. More reproducible and, probably, unbiased data may be drawn from the composite curves obtained by superimposing the breaths either at total lung capacity or on the descending limb.

Adult↗
PubMed1978

[Von Recklinghausen's disease: functional pulmonary changes. 2 case reports].

We report two cases of patients with Von Recklinghausen disease. They exhibited typical cutaneous and diffuse intrapulmonary lesions accompanied by effort dyspnea. Multiple radiological abnormalities were noticed and the pictures showed nodular and interstitial lesions as well as emphysematous areas. Pulmonary function tests revealed more or less marked hypoxemia without hypercapnia, and decreased maximal expiratory flows due, at least in part, to a loss of elastic recoil.

Adult↗
PubMed1978

The respiratory response to inhaled carbon dioxide in man after 3 hours exposure to 3% carbon dioxide.

1. The respiratory response to inhaled 3% and 6% CO2 was measured in 10 normal subjects after a 3 h acclimatization period to 3% CO2 in an environmental chamber. Control studies were carried out after a 3 h period of breathing air in the chamber. 2. At the end of the acclimatization period studies were carried out during 20 min periods breathing 3% CO2, 6% CO2 and air. 3. At 2-min intervals during the studies measurements were made of tidal volume (Vt), breathing frequency (fR), minute ventilation (Ve), viscous pulmonary rate of work (Wp) and total viscous rate of work across the lungs and apparatus (Wt). Blood gas tensions were measured at the end of this period. 4. After acclimatization to 3% CO2 there was a significant shift in the response curves Ve/Pa,CO2 and Wt/Pa,CO2 such that subjects showed higher Pa,CO2 values for given values of Ve or Wt. There was no significant change in the slope of the response curves. 5. No correlation was found between the slope of the response curve after the control period breathing air and the degree of shift of the response curve. 6. There was no difference in respiratory pattern or in pulmonary resistance. 7. Similar results were found in two subjects studied after 24 h acclimatization to 3% CO2 but one subject also showed a significant change in the slope of the Ve/Pa,CO2 curve.

Acclimatization↗
PubMed1978

Breath sounds in the clinical assessment of airflow obstruction.

In a group of 34 inpatients showing varying degrees of airflow obstruction we studied the relationship between breath sound intensity (BSI) and abnormalities of lung function. The BSI was evaluated by chest auscultation to provide a score, in a manner similar to that described by Pardee et al. (1976), and was found to correlate closely with indices of airflow obstruction of their logarithms such as specific conductance (r = 0.759), maximal expiratory flow at 50% of vital capacity (r = 0.790), forced expiratory volume in one second (r = 0.768), and forced expiratory volume to vital capacity ratio (r = 0.860). Correlations with lung volumes, although statistically significant, were weaker. Multiple correlation studies showed that BSI score correlated independently with indices of both airflow obstruction and lung distension. In our experience, BSI score can be useful not only in the detection but also the quantification of airflow obstruction, although its predictive power is impaired in subjects with associated restrictive disorders. It can also fail to detect mild, pure airflow obstruction.

Adult↗
PubMed1977

[Pulmonary mechanics and alveolar exchanges in the elderly with apparently healthy lungs. Preliminary study].

A group of ten elderly subjects who were apparently normal from the cardiac and pulmonary points of view, were selected on criteria of history, clinical findings, radiological and E.C.G. findings, with a view to a study of respiratory function based on two aspects: alveolar exchanges were assessed by measurement of the ductance of carbon monoxide and the elastic properties of the lung together with bronchial permeability. Although alveolar exchanges are little modified, one may note some pulmonary distension, especially in the smokers, together with a reduction in elasticity. The changes in bronchial permeability which affect the peripheral and central airways, are mainly found in smokers. One may determine the respective roles of extrinsic and intrinsic bronchial obstruction in these abnormalities. One may thus consider that, from the pulmonary point of view, the elderly patient faced with a surgical operation should be considered a high risk for respiratory decompensation, especially if he is, or has been, a smoker.

Aged↗
PubMed1976

Modeling of the relationship between volume variations at the mouth and chest.

A model was developed to interpret the difference between volume variations at the mouth and at the chest observed by body plethysmography during inspiration in normal subjects breathing ambient air. The mechanical phenomena were characterized, as usual, by a time constant alpha, the product of airway resistance and alveolar gas compressibility. In contrast to other models, the change in temperature and water vapor pressure of the inspired gas was not considered to be instantaneous but rather a first-order process characterized by a thermal time constant tau. Experimental curves obtained in eight subjects were analyzed by use of parameter estimation techniques. The values of alpha were in agreement with those obtained by conventional plethysmography and tau averaged 63+/-24 ms. The results of additional experiments devised to test the physical meaning of the coefficients and the influence of neglected factors support the validity of the model. It was shown that tau cannot be neglected when breathing air at room temperature.

Humans↗
PubMed1975

Frequency response of the chest: modeling and parameter estimation.

The frequency response of the respiratory system was studied in the range from 3 to 70 Hz in 15 normal subjects by applying sinusoidal pressure variations around the chest and measuring gas flow at the mouth. The observed input-output relationships were systematically compared to those predicted on the basis of linear differential equations of increasing order. From 3 to 20 Hz the behavior of the system was best described by a 3rd-order equation, and from 3 to 50 Hz by a 4th-order one. A mechanistic model of the 4th order, featuring tissue compliance (Ct), resistance (Rt) and inertance (It), alveolar gas compressibility (Cg) and airway resistance (Raw), and inertance (Iaw) was developed. Using that model, the following mean values were found: Ct = 2.08-10(-2)1-hPa-1 (1 hPa congruent to 1 cm of water); Rt = 1.10-hPa-1(-1)-s; It = 0.21-10(-2)hPa-1(-1)-s2; Raw = 1.35-hPa-1(-1)-s; Iaw = 2.55-10(-2)hPa-1(-1)-s2. Additional experiments devised to validate the model were reasonably successful, suggesting that the physical meaning attributed to the coefficients was correct. The validity of the assumptions and the physiological meaning of the coefficients are discussed.

Airway Resistance↗
PubMedDate not supplied

Effect of atrial natriuretic peptide on bronchial tone in anesthetized rabbits.

The effect of atrial natriuretic peptide (ANP) on histamine-induced bronchoconstriction was studied in vivo (in normoxic and in hypoxic rabbits) and in vitro. Thirty-two anesthetized rabbits, spontaneously breathing room air or 10% O2, received infusions of ANP (20, 40, or 80 ng/min/kg normoxia; 20 ng/min/kg hypoxia) or the vehicle for 100 min. After 75 min of ANP infusion, bronchoconstriction was induced inhaling histamine; respiratory resistance (Rrs) was measured prior to and until 20 min posthistamine. The results show that the histamine-induced increase in Rrs was significantly reduced by ANP 80 ng/kg/min in normoxia, and by ANP 20 ng/kg/min in hypoxia. In vitro, ANP had no effect on tracheal and bronchial smooth muscle precontracted with histamine or acetylcholine. These results show that ANP can decrease a histamine-induced bronchoconstriction in vivo but not in vitro, suggesting an indirect mechanism of action.

Airway Resistance↗
PubMedDate not supplied

Effect of growth on surface charge and hydrophobicity of Staphylococcus aureus.

Modifications in the surface charge and hydrophobicity of Staphylococcus aureus Oxford during growth were studied by analysing electrophoretic mobility and adherence to hydrocarbons (hexadecane), respectively. Bacterial concentration had no effect upon the measurements. Both surface charge and hydrophobicity varied during the exponential phase of growth (1 to 4 h): surface charge decreased significantly (p less than 0.001), while hydrophobicity increased (p less than 0.001). In the stationary phase (4 to 9 h), the surface charge increased significantly (p less than 0.001), whereas hydrophobicity showed no change. Cationized ferritin decreased the surface charge and had no effect on hydrophobicity. These results suggest that in S. aureus, different structures could be responsible for their surface charge and hydrophobic properties.

Alkanes↗
PubMedDate not supplied

[A diagram to analyse airways patency abnormalities (author's transl)].

The factors contributing to airflow obstruction in chronic respiratory diseases are frequently investigated by measuring an index of airways patency : 1) at various lung volumes, which permits to detect and quantify the obstruction, 2) at different static recoil pressures (Pst) to recognize abnormalities not related to a loss of elastic recoil. A diagram has been developed which facilitates the analysis and permits a more quantitative evaluation of intrinsic and extrinsic factors : the index of airways patency (I) is plotted simultaneously against Pst and against lung volume (expressed in % of predicted TLC), the two abscissae being scaled in such a way that the normal ranges are coincident for the two curves. Then, the distance from the I(Pst) curve to the normal range may be used to estimate the abnormalities due to intrinsic factors, and the distance between the two curves to evaluate extrinsic obstruction. Taking maximum expiratory flows as the index of airways patency, examples are shown to illustrate the use of the diagram.

Airway Obstruction↗