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Biomedical subjects

R Barthelemy

Publications and source records attributed to R Barthelemy.

At least 19 recordsLinked to original sources

[The Bimler method in the treatment of sagittal shift of the skeletal base in Class II division 1 malocclusion].

Inadequate sagittal development of the mandible (class II, division 1 malocclusion), is one of the most frequent in dentofacial malformations. We present the Bimler "gebissformer", removable and functional appliance and its tridimensional action. The treatment can be started during the deciduous dentition or in mixed dentition. Therapeutic results, increase of SNB angle, maxillary expansion, and reduction of the deep bite are presented. While therapeutic failure is observed in 30% of the cases (by absence of tissular response or poor patient compliance), the stability of the results in 70% of the remaining cases and its total inocuity make this appliance an interesting method of treatment.

Age Factors

Closed loop control of PaCO2 during ECC.

A prototype for the control of blood gases during extracorporeal circulation (ECC) has been built. It is composed of a CDI300 continuous gas blood analyzer, a programmable gas blender and an IBM PC. The air blender is composed of three mass flow controllers (air, oxygen and total flow rate). The microcomputer commands these controllers in order to obtain the desired mixture of air and oxygen. The system acquires the data sent by the blood gas analyzer every 6 seconds and commands the gas blender in order to maintain the desired arterial dioxide partial pressure (PaCO2) in the arterial line. The first experimental results on sheep show that if blood gas parameters are stable when beginning the closed loop control, then the desired PaCO2 value may be obtained. Otherwise, the value of PaCO2 under control is slightly different but a stable value is obtained after 10 minutes. More experiments must be done in order to establish the real limits of such a system and optimize the gain of the control system.

Animals

Evaluation of a cardiopulmonary preservation method for heart-lung transplantation.

This study was designed to examine whether concomitant administration of anti-free radicals with donorcore cooling on cardiopulmonary bypass (CPB) and hypothermic storage of the heart and lung, could provide successful extended cardiopulmonary preservation. Fourteen sheep heart-lung blocks harvested after core-cooling and cardioplegic arrest were preserved at 4 degrees C for 8.5 hr. Before and during CPB, the animals were perfused with Prostaglandin E1 (PGE1), superoxide dismutase (SOD), catalase (CAT) and deferoxamine (DEF). Cardioplegic arrest was induced with St. Thomas' Hospital solution (Plegisol) to which SOD, CAT and DEF had been added. The preservation solution consisted of Plegisol modified by the addition of K-lactobionate, raffinose, mannitol, SOD, CAT, DEF, a phosphate buffer and penicillin. Histological examination performed on 3 donor heart-lung blocks before and after CPB and cardioplegia, then immediately following cold storage, produced no clear evidence of structural damage in cardiac myocytes and lung parenchyma. Eleven donor organs were therefore transplanted in size-matched recipients with a total mean ischemic time of 12 hr. The combined administration of SOD, CAT, DEF, insulin and glucose during the initial period of reperfusion had no beneficial effect on cardiopulmonary performance. A progressive fall in Pa O2 and mean aortic pressure was observed post-operatively in the 7 animals that were weaned from CPB. Five of them died within 3 to 5 hr after CPB weaning, the remaining 2 animals died of cardiac arrest within the fourth hour. The results of this experiment seem to indicate that: 1. better organ function and improved survival could have been obtained if the duration of anti-radical treatment had been prolonged after reperfusion and, 2. physical manipulation of the donor grafts during harvesting and transplantation may have been partly responsible for the poor post-transplantation cardiopulmonary performance.

Animals

[Heart-lung preservation: historical evolution and current research data].

Over the past decade, combined, heart-lung transplantation has been established as a therapeutic modality for many patients with end stage cardiopulmonary disease. However, the scarcity of suitable donors and the lack of a reliable and simple technique for distant organ procurement have somewhat limited its practice. The normothermic autoperfusion preparation has been utilized in a few satisfactory distant heart-lung preservation and subsequent transplantation, but this method is rather cumbersome. Single cold flush perfusion of the pulmonary artery with infusion of prostaglandin E1, a powerful vasodilator of the pulmonary bed, has been used successfully in heart-lung preservation for transplantation. Donor core-cooling through cardiopulmonary bypass without pulmonary artery flush perfusion appears to provide longer and better graft protection since it improves its function. The production of oxygen radicals after reperfusion of ischemic tissues has important implications in organ preservation and transplantation. Recent studies in the prevention of reperfusion injury indicate that enzymatic scavenger and iron chelator therapy may play an important role in the reduction of reperfusion injury in the clinical setting of heart-lung transplantation.

Cryopreservation

Automatic modules for extracorporeal circulation control.

Maintenance of a constant level in the oxygenator during surgical extracorporeal circulation (ECC) is of paramount importance. We propose a device able to regulate the pump speed accordingly to the level in the oxygenator, and an automatic clamp to control venous return from the patient. The level regulator permits pump speed control and also stops the pump when a prefixed low level is reached (during ECC). Linearization of the level sensor has been made in order to optimize the PI regulator. Simulation results are presented and the regulator is evaluated in a clinical environment. The automatic clamp provides a good solution for reproducible and easy transitions in venous return. When coupled with the level regulator, the pump speed will increase automatically from zero to the correct equilibrium speed, with variable duration (from 30 seconds to 5 minutes) chosen by the operator. The same technique is used for stopping the ECC. These two devices are, in fact, modules, making up part of an evolutive device for ECC automation. The modules can exchange data with a supervising microcomputer.

Automation