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.

[Comparison of postoperative blood cortisol levels after neuroleptanalgesia and extradural anesthesia]. / Comparaison de la cortisolémie post-opératoire après neuroleptanalgésie et anesthésie extra-durale.

Postoperative plasma cortisol levels were measured in two series of surgical patients who had undergone a gynaecological operation, with respectively 17 and 16 subjects. Samples were drawn on D0 6pm, D1 8am, D2 8am and D3 8 am. A reference sample had been taken before the premedication on D0 at 8 am. The first series had been anaesthetised using a dextromoramidedroperidol type neuroleptanalgesia followed by postoperative analgesia by a noramidopyrine compound. The second series required epidural anaesthesia followed by postoperative analgesia by the injection of lidocaine at constant rate, interrupted between the last two samples. In the neuroleptanalgesia group: from a basal level of 470 nmol.l-1, plasma cortisol rose to 800 nmol.l-1 (p less than 0.01) on D0 at 6 pm to subsequently remain on a plateau between 500 and 550 nmol.l-1 (NS) within the normal physiological limits for the laboratory. In the epidural group, from a basal level of 420 nmol.l-1, plasma cortisol rose to 1000 nmol.l-1 (p less than 0.01) to return to basal levels only on D3: 450 nmol.l-1 (NS) with intermediate values of 700 and 630 nmol.l-1 (respectively: p less than 0.001 and p less than 0.05). Statistical comparison between the two groups showed that the increase in cortisol in the epidural group in relation to the other was significant throughout the period of administration of lidocaine at constant flow rate: p less than 0.05 on D0 at 6pm, D1 and D2. The results are discussed.