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Biomedical subjects

R Sartène

Publications and source records attributed to R Sartène.

4 recordsLinked to original sources
PubMed2001

Scaling behavior in beta-wave amplitude modulation and its relationship to alertness.

We performed an experimental study of beta waves occurring in human electroencephalographic signals obtained from six healthy subjects that were monitored during the performance of a task requiring attention to auditory signals. We use wavelet analysis to study whether the fluctuations in the modulation of the beta-wave amplitude related to an indirect measurement of alertness. We found that these fluctuations exhibit a power-law behavior. When the level of alertness dropped, the associated exponent was found to increase, reflecting the fact that long-range correlations grow rapidly within the system. We also studied the fluctuations of amplitude modulation for alpha and theta waves, for which we did not find a power-law behavior.

Acoustic Stimulation↗
PubMedDate not supplied

Evaluation of the end-expiratory lung volume as an indirect index of bronchial constriction in asthma.

The purpose of this study was to evaluate the merits of the end expiratory lung volume as an indirect ventilatory index of bronchial obstruction and to show an application of continuous monitoring of lung volume in asthmatic patients. The accuracy of the external measurements (IS) of functional residual capacity (FRC) was controlled by comparing them with the helium measurements (DS) obtained during nine methacholine tests (IS = 0.06 + 1.065 DS in litres: R2 = 0.99). Seven asthmatics (18-48 yr) were monitored by measuring rib cage and abdominal perimeter variations. This was done in basal condition, after methacholine-induced bronchoconstriction and after bronchodilation by either salbutamol or oxytropium bromide inhalation. All the subjects were investigated on two separate days and were their own control. Bronchoconstriction produced a significant increase (p less than 0.01) of tidal volume (VT: + 67%), external minute ventilation (VE: + 58%), mean inspiratory flow (VT/TI: + 78%) and FRC (+ 26.5%) while frequency (f) and fractional inspiratory time (TI/TT) fluctuated non significantly. In the group of seven tested subjects, there was a significant correlation (p less than 0.01) between forced expiratory volume in one second (FEV1) and VE, FEV1 and VT/TI, FEV1 and FRC. However, the individual regression line showed a significant relationship only between FEV1 and FRC (R2 = 0.80 +/- 0.04). We therefore conclude that the variation of the end expiratory level can be chosen as an indirect index of bronchoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Evaluation of differential linear transformers as a non-invasive ventilatory method in supine subjects.

We present a new method to measure thoraco-abdominal perimeter variations using differential linear transformers inserted in belts. The high sensitivity (250 mV/mm), the low time drift (1 mV/24 h compared to a 1 V output for a tidal volume), the good frequency response (up to 10 Hz) and low cost (12,000 FF) are the major advantages over other devices. After calibration (using change contribution of thorax and abdomen and the least square method for calculation of volume-motion coefficients), estimated tidal volumes in 23 adults in supine position are within 0.06 +/- 5.17% and changes in functional residual capacity (43-453 ml) are within 3.4 +/- 15.3% when compared with direct spirometry. These results show that the method can be used to monitor ventilation accurately in supine healthy subjects.

Adolescent↗