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Biomedical subjects

G Saumon

Publications and source records attributed to G Saumon.

At least 73 records · Page 4Linked to original sources
PubMed1982

K, Cl, and H2O entry in endolymph, perilymph, and cerebrospinal fluid of the rat.

The kinetics of radioactive potassium, chloride, and water entry into endolymph, perilymph, and cerebrospinal fluid were studied after intravenous administration of tracers in anesthetized and nephrectomized rats. Samples of cochlear endolymph, perilymph of scala vestibuli, perilymph of scala tympani, and cisternal cerebrospinal fluid were obtained. The data showed: 1) a rapid turnover of water in endolymph, perilymph, and cerebrospinal fluid, since 3H2O equilibrated with plasma in a few minutes; 2) a slow entry of 42K and 36Cl in perilymph, since 36Cl equilibrated with plasma after 2 h and 42K did not at 6 h; 3) an extremely slow entry of 42K and 36Cl in endolymph, since no equilibrium with plasma was obtained within the 5 h of the experiments. The comparison of the compartmental analysis of our data with the results of other studies using perilymphatic perfusion of tracers indicated that perilymph rather than plasma may be considered as the precursor of endolymph.

Animals↗
PubMed1982

Nonlinear fluid systems identified by random noise input.

The usual impedance measurement by Fourier analysis leads to undetectable errors when applied to nonlinear fluid systems where a nonlinear pressure drop p = K X V2 adds to the linear pressure-flow relationship, but processing series of impedance data with various input levels allows the measurement of such systems. This new method has been tested on simulations, nonlinear resistances, and intubation tubings. It gives accurate estimates of the nonlinear coefficient K together with the true linear impedance of the measured system. This way, the usual respiratory impedance measurement may be applied to intubated patients, as the respiratory impedance of the subject can be separated from the nonlinear behavior of the endotracheal tube or cannula.

Airway Resistance↗
PubMed1981

Depression of respiratory drive by diazepam as premedication.

The respiratory effects of premedication with i.v. injection of diazepam have been assessed in 10 healthy patients awaiting minor operative procedures. Measurements were recorded before and 60 min after administration of diazepam 0.14 mg kg-1. Mouth occlusion pressure (P 0.1) was used as an index of neuromuscular inspiratory drive. Minute-ventilation (VE), respiratory frequency (f) and mean inspiratory flow rate (VT/TI) were significantly reduced after diazepam. During carbon dioxide rebreathing the slopes of VE, f, VT/TI and P 0.1 with PACO2, were significantly reduced. These results confirm that i.v. diazepam produces significant respiratory depression in healthy subjects. We conclude that diazepam used under clinical conditions depresses the respiratory centre.

Adult↗
PubMed1980

An analog device to facilitate occlusion pressure measurements.

The "oclusion pressure" technique is widely used to test the response of respiratory centers to CO2. The graphic treatment of the test necessitates a fast recording of the mouth pressure signal, thus using a great deal of paper and requiring a tedious interpretation. The device described here controls an electromagnetic valve closing it during expiration and opening it after a given time delay, following the onset of inspiration. During that time only, the mouth pressure signal goes through an analog switch, the highest signal value is then equal to the occlusion pressure. This device allows the use of a slow recorder without loss of information. In addition, it has the advantage of generating very short respiratory occlusions, thus sparing the subject being tested from interferences in subsequent respiratory cycles. It can be used as a pretreatment unit to be associated with a microprocessor.

Carbon Dioxide↗
PubMed1980

Identification of transducer defect in respiratory impedance measurements by forced random noise. Correction of experimental data.

The measurement of respiratory impedance by means of the forced oscillations technique depends on the frequency response of various measurement devices: pressure transducers, flowmeter, filters, etc. In the range of frequencies where measurements were done (0--100 Hz) it is difficult to have the same response (amplitude and phase) for mouth pressure and flow transducers. It is possible to identify the relative frequency response of both devices. This can be done by comparison of measurements made on a well-defined mechanical system with a theoretical model representing this system. The method also avoids separate frequency calibrations of pressure and flow. Its validity depends only on the accuracy of the model of impedance of the standard system used.

Airway Resistance↗
PubMed1980

Characterization and validation of forced input method for respiratory impedance measurement.

We have studied the effect of spontaneous breathing on the measurement of total respiratory impedance by the oscillation method, that is using forced random pressure input. Free breathing of the subject induces parasite signals on the pressure and flow measured at the mouth. These induced random signals are correlated through a loudspeaker box with side tubing and flowmeter impedance. The respiratory impedance of the subject, calculated by the cross-power spectrum method, is shown to be systematically biased. This bias is obvious in a calculation model, experimentally verified by an analogue electrical experiment. The validity of the method depends on the respiratory noise level which affects the correlation between the forced pressure input and related flow output. The impedance of the apparatus should thus be minimized in order to decrease the respiratory noise. In this manner, the bias would be shifted to lower frequencies and the accuracy of the measurement near the resonant frequency of the respiratory system would be improved.

Airway Resistance↗
PubMed1980

Fazadinium pharmacokinetics in patients with liver disease.

Serum concentrations of fazadinium were measured in eight patients with cirrhosis and eight patients with total biliary obstruction who underwent abdominal surgery. A biexponential decay of the concentration was observed after a single i.v. injection of fazadinium. A two-compartment open model was used in the pharmacokinetic analysis of the data. The pharmacokinetic parameters were compared with those obtained in 11 normal patients. A 90% increase in both the distribution half-life (T 1/2 alpha), from 10 to 19 min, and in the elimination half-life (T 1/2 beta), from 82 min to 153 min, was observed in patients with cirrhosis. These changes are the consequence of an increase (60%) in the total apparent volume of distribution (V). In contrast, the plasma clearance (Cl) was not modified. Total biliary obstruction was associated with very little change in the pharmacokinetics of fazadinium, T 1/2 beta being slightly prolonged to 103 min. No significant decrease in plasma clearance was observed in patients with cholestasis. These results suggest that biliary excretion of fazadinium does not represent an important supplementary pathway to renal excretion. The relatively rapid decrease of the blood concentration of fazadinium compared with other non-depolarizing relaxants is probably related to another extrarenal pathway of elimination which has not yet been identified.

Abdomen↗
PubMed1978

Chronic cor pulmonale in pulmonary sarcoidosis.

Right-heart overload happens relatively rarely in sarcoidosis, even with fibroemphysematous changes. Of 21 cases that we studied, six (28%) had clinical and/or electrocardiographic features of cor pulmonale. The cause of cor pulmonale often evoked is an invasion of the walls of pulmonary vessels by sarcoid granulomas or their compression by the fibrotic process. Pathological studies in one patient showed compression of large pulmonary arteries associated with specific sarcoid lesions in small small and medium-sized arteries.

Adult↗
PubMed1978

The relationship of age to pulmonary membrane conductance and capillary blood volume.

The lung transfer components of 70 normal, adult nonsmokers 18 to 78 years of age were measured by the single-breath diffusing capacity of the lung for CO. The membrane conductance and the pulmonary capillary blood volume were estimated by several measurements of the diffusing capacity at increasing alveolar PO2. Diffusing capacity, membrane conductance, and pulmonary capillary blood volume are functions of biometric references (height or alveolar volume) and of age. The observed decrease with age was more evident after 40 years of age for diffusing capacity and membrane conductance. Pulmonary capillary blood volume decreases at a later age. The changes in membrane conductance and pulmonary capillary blood volume with age may be due either to morphologic changes in the alveolar capillary surface or increasing inhomogeneities of distribution or both.

Adolescent↗