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Biomedical subjects

M Baud

Publications and source records attributed to M Baud.

At least 37 records · Page 2Linked to original sources
PubMed1994

Measurement of CO2 response with the breath-by-breath automatic acquisition of the breathing pattern and occlusion pressure.

OBJECTIVE: Our objective is to present a methodology for the automated acquisition and storage of BP and P0.1 during a CO2 rebreathing test. METHODS: The system consists of a microcomputer with additional circuits and an automatic electronically controlled valve to occlude the inspiratory airway. Data collection and data processing are separate programs. Airway pressure and flow are digitized at a 100-Hz rate, while PETCO2 is determined and P0.1 is measured on a breath-by-breath basis. Off-line processing calculates the BP variables, generates a correlation matrix (VE/PETCO2, TTOT/PETCO2, TI/PETCO2, TE/PETCO2, [VT/TI]/PETCO2, [TI/TTOT]/PETCO2, P0.1/PETCO2), and edits graphic data. The accuracy of the volume and pressure measurements was tested by comparing known volumes provided by a syringe (n = 100) and a series of pressures controlled by a water manometer (n = 41) on the one hand, with volumes and pressures measured by the device. The accuracy of the time intervals and P0.1 was assessed by comparing in 10 healthy subjects the values measured manually on a graphic recording with those provided by the device (n = 170). RESULTS: Volumes:Vmeasured = 0.99 x Vcontrolled, r = 0.99, p < 0.001. Pressures:Pmeasured = 0.97 x Pcontrolled + 0.09, r = 0.98, p < 0.001. Inspiratory time:TIautomatic = 0.91 x TIgraphic + 0.22, r = 0.93, p < 0.001. Expiratory time:TEautomatic = 0.93 x TEgraphic + 0.34, r = 0.95, p < 0.001. Occlusion pressure:P0.1automatic = 0.95 x P0.1graphic + 0.62, r = 0.94, p < 0.001. Reproducibility was assumed to be represented by the intraindividual coefficient of variation of the CO2 response. The comparison of an automatic breath-to-breath method with a graphic manual recording revealed significantly less variability with the former (VE/PETCO2: 15.2 +/- 4.5% vs 22.5 +/- 6.3%, p < 0.01; P0.1/PETCO2:8.3 +/- 4.3% vs 19.7 +/- 7.2%, p < 0.001; [VT/TI]/PETCO2:9.1 +/- 3.5% vs 14.5 +/- 5.3%, p < 0.05). CONCLUSION: Our automated acquisition and storage of waveforms and breath-by-breath determination of BP and P0.1 provide an easy and thorough analysis of the respiratory response to CO2 and decrease the variability of the results.

Anesthesia, Closed-Circuit↗
PubMed1994

Oral immunization with bacterial extracts for protection against acute bronchitis in elderly institutionalized patients with chronic bronchitis.

Acute bronchitis is a major source of morbidity in elderly patients. The purpose of this study was to assess the preventive effects of oral immunisation with a bacterial extract. Three hundred and fifty four patients with chronic bronchitis, living in institutions for the elderly (aged > 65 yrs), were included in a randomized, placebo-controlled, double-blind study. The purpose of the study was to assess preventive effects of OM-85 BV (an immunostimulating agent consisting of lyophilized fractions of eight of the most common pathogens isolated in respiratory tract infections) against acute lower respiratory tract infections. Two hundred and ninety patients completed the study (143 taking placebo and 147 taking OM-85 BV). There was a 28% reduction in the number of lower respiratory tract infections in the patients treated with OM-85 BV; this was entirely due to 40% reduction in the number of episodes of acute bronchitis (p < 0.01), with no difference in the number of episodes of pneumonia and bronchopneumonia. A larger number of patients in the OM-85 BV group were free of acute bronchitis throughout the 6 month study period (96 vs 69) and there was a 28% reduction in the number of antibiotic prescriptions in the OM-85 BV treated group. These results suggest that OM-85 BV has a protective effect against acute bronchitis in elderly patients living in institutions.

Aged↗
PubMed1993

A rapid, simple method for calculating equilibrium constants and antibody site concentrations from dilution curves alone.

A rapid new practical method for calculating both the antibody-antigen equilibrium constant and the antibody concentration from antibody dilution curve data alone is described. This method is faster than the inhibition curve method for evaluating a humoral immune response. It is particularly suitable for monitoring the immune response of an immunization program. The response is assessed as an immunization index, Abi*Ka. This index is more exact than the antibody titer obtained from dilution curves and independent of the specific activity of the labelled molecule and total activity used in the assay. The method was used to monitor the production of a monoclonal antibody to the sulphide peptide leucotriene including immunization, cloning and purification.

Algorithms↗
PubMed1993

[Preventive effect of an immunomodulator, OM-85 BV, on acute exacerbations of chronic bronchitis in elderly patients. Preliminary results at six months in 291 patients].

Three hundred fifty six patients aged 65 years or more (mean age 81.8 years) who were suffering from chronic bronchitis were included in a double-blind trial against placebo to assess the preventative effect of OM-85 BV against acute exacerbations of chronic bronchitis. OM-85 BV is an immunostimulant composed of lyophilised factions of 8 bacteria which are most frequently encountered during the course of respiratory tract infections. 291 patients completed the study. In the group treated by OM-85 BV, a significant increase in the number of patients with no episode of acute bronchitis was noted (96 versus 71, p = 0.006). There was a 38.8% reduction in the absolute numbers of episodes of acute bronchitis and a 33% reduction in the number of prescriptions for antibiotics, however there was no difference in the number of pneumonias and bronchopneumonias. These results show the protective effect of OM-85 BV against bronchial superinfections in a large population of elderly patients suffering from chronic bronchitis.

Acute Disease↗
PubMed1992

Effects of doxapram on hypercapnic response during weaning from mechanical ventilation in COPD patients.

Failure of weaning from mechanical ventilation in COPD patients is often related to diaphragmatic fatigue. Whether there is a central respiratory drive fatigue and a reserve of excitability is still debated. The purpose of this study was to analyze the following in 13 COPD patients weaned from mechanical ventilation: (1) ventilatory (VE/PETCO2) and neuromuscular (P0.1/PETCO2) response to hypercapnia; (2) the maximum reserve capacity measured through changes in the VE/PETCO2 and P0.1/PETCO2 slopes after doxapram (DXP) infusion, which, given during the test, allows measurement of the maximum response capacity to overstimulation; and (3) analyze the influence of these changes on the outcome of weaning. The results show a variable P0.1/PETCO2 response and a low VE/PETCO2. DXP infusion does not change the slopes of these relations but increases the end-expiratory volume (delta FRCd); (p less than 0.02). Since there was no change in the VE/PETCO2, P0.1/PETCO2, and delta FRC values with or without DXP, there was no excitability reserve in patients who were successfully weaned. When weaning failed, DXP did not change VE/PETCO2 and P0.1/PETCO2 slope, but delta FRCd was greater the delta FRC (p less than 0.001). The excitability reserve in these patients leads to an increase in end-expiratory volume, probably worsening the diaphragm dysfunction.

Aged↗
PubMed1991

Transforming signals into quantitative values and mathematical treatment of data.

The purpose of this article is to review some mathematical models which are available to calibrate immunoassays and interpolate analyte concentration. Several curve fitting methods are available, but few of them are currently used. Point-to-point linear interpolation is prone to bias when the rate of curvature of the calibration curve or when the random error are high. Polygonal interpolation connects each neighboring pair of data points with multiple connected line segments. Neither smooths the data. Smoothing models are often preferred because they can correct some of the random error. Weighted least squares must be used when the calibration points have nonhomogeneous variance. The most used methods are empirical (spline function) or semi-empirical (logit-log, logistic). The logitlog straight line is often too rigid. Logistic equation can fit numerous assays. The best empirical model is the smoothed cubic spline. Model-based methods attempt to describe the data in terms of a given theoretical model for the assay chemistry. The choice of a method to efficiently control calculations must take into account the quality of the fit, the robustness with outliers, the proper computation of confidence limits and the user-friendliness. Errors associated with the different processing steps can also be due to the calibration point distribution, the axes in which the curve is shown, the model used, and, of course the measurement errors.

Data Interpretation, Statistical↗
PubMed1991

[Broncholithiasis of the upper right lobe].

A case of right upper lobe broncholithiasis is reported in a 50 years old smoker man. The first diagnosis was bronchial carcinoma but the diagnosis was made finally by fiberoptic bronchoscopy and scannography. The outcome remains favourable without treatment. The value of scannography for diagnosis and follow-up is underlined.

Bronchial Diseases↗
PubMed1989

[Hyperoxia test during attempts to withdraw artificial ventilation].

A 30 minute test of hyperoxia (10 l.min-1) was conducted in patients (n = 21) with chronic obstructive lung disease during the weaning trials from mechanical ventilation. Two groups were formed according to whether the occlusion pressure at 100 ms (PO.1), index of central stimulation, decreased or not during the test. The first group lowered PO.1 and increased PaCO2 by decreasing VE (minute-ventilation), VA (alveolar ventilation) and increasing the VD/VT ratio; the others had a lower PO.1 and did not modify it after administration of 02 despite a lowered PaO2 initially identical to that in the first group. They held PaCO2 constant by increasing VE and by maintaining VA in relationship with an improvement in diaphragm contractility and/or a better response to hypercapnia stimulus. All the patients is this group were successfully weaned eight days after the study period.

Aged↗
PubMed1988

Comparison between vertical parallel hole collimator and 30 degrees rotating slant hole collimator for assessing global and regional left ventricular function by radionuclide angiography.

Left ventricular ejection fraction (LVEF) and regional wall motion abnormalities were determined in 40 patients (30 with coronary artery disease and 10 with valvular heart disease) using equilibrium radionuclide angiography. Scintigraphic acquisitions were collected in random order with 2 different collimators as follows: in anterior face (AF), left anterior oblique (25 degrees-45 degrees LAO) and 70 degrees LAO, with a vertical parallel hole collimator (VTC), and in 25 degrees-45 degrees LAO and 65 degrees-80 degrees LAO with a 30 degrees rotating slant hole collimator (RSHC), with the slant of the collimator directed towards the cardiac apex in both projections. Results were compared to contrast ventriculography (CV) performed in the 30 degrees right anterior view (3 segments: anterior, apical, inferior) and in a 60 degrees left anterior oblique view (3 segments: septal, apical and lateral). Radionuclide LVEF in both series was closely correlated with contrast ventriculographic LVEF (r = 0.89, VTC vs CV and r = 0.87, RSHC vs CV, respectively). Regional wall motion analysis was only performed among the 30 patients suffering from coronary heart disease. Eight contrast angiographic studies were normal and 22 abnormal. Global sensitivity and specificity were 100% and 63% with the VTC (3 false positives) and 91% and 87% with the 30 degrees RSHC (2 false negatives and 1 false positive, P = ns). Agreement for the localisation of the regional wall motion abnormalities between CV and radionuclide angiography was 70.6% with the VTC and 71.2% with the RSHC (P = ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1988

[Exertion-induced parameters of left ventricular function in patients with chronic cardiac insufficiency. An isotope study].

Exercise-induced changes in haemodynamic values were studied by radionuclide ventriculography in 21 patients with permanent systolic dysfunction (15 with non-obstructive cardiomyopathy and 6 with ischaemic heart disease). The results were compared with those obtained in 8 control subjects with normal heart. In healthy subjects, during exercise the ejection fraction increased due to constant diminution of the end-systolic volume; the end-diastolic volume and the systolic ejection volume did not significantly vary; the cardiac output augmented only because of the accelerated heart rate. In patients with permanent left ventricular dysfunction, the ejection fraction remained unchanged during exercise, whereas the end-systolic volume increased significantly. Yet the systolic ejection volume increased due to a rise in end-diastolic volume. Heart rate and cardiac index increased, but not as much as in normal subjects. There was a close correlation between changes in end-diastolic and end-systolic volumes. It was the relative importance of changes in these two ventricular volumes that determined the direction and amplitude of variations in ejection fraction. It is concluded that in patients with permanent left ventricular dysfunction: (1) the end-systolic volume increases during exercise, thus betraying a worsening of the systolic dysfunction; (2) however, the systolic ejection volume is maintained or increases due to an increase in end-diastolic volume; (3) the changes in ejection fraction observed during exercise are of little value to characterize the modifications that occur in left ventricular work performance.

Adult↗
PubMed1986

[Aspergillosis with obstruction of the central airways].

Two cases are reported of obstruction of central airways by plugs containing Aspergillus fumigatus. In one case the obstruction was located in the right stem bronchus and, despite treatment with amphotericin B, the immunocompromised patient died from invasive disseminated aspergillosis. In the other case the obstruction was in the trachea and, since the immune function of the patient was normal, she responded favorably to treatment by amphotericin B.

Adolescent↗