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Biomedical subjects

G Janvier

Publications and source records attributed to G Janvier.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Medico-legal dimension of informed consent in medicine].

The practice of the medical arts is more and more becoming framed by laws and regulations. Concurrently, the civil liability in the medical field has also been deeply changed, in particular by reversing the charge of proof of the information given to the patient. After having been reminded of the place in the juridical arsenal of informed consent to a medical procedure, its value is discussed regarding the explanations given by the physicians. Guidelines for a forensic appraisal, with the aim of evaluating and appreciating the information received by the patient, are proposed. Recent judiciary decisions about refusal of care, especially blood transfusions, are discussed.

France↗
PubMed1999

[Cellular energy metabolism: physiologic and pathologic aspects].

Cellular homeostasis requires permanent energy production and consumption. Adenosine triphosphate (ATP) is the major energy component for the cell. Its synthesis occurs mainly in mitochondria where the oxidative phosphorylations realise the coupling between oxygen consumption and phosphorylation of adenosine diphosphate. The anaerobic production of ATP plays an important role in the intermediary metabolism. The enzymatic complexes of the mitochondrial respiratory chain are energy transducers acting as proton pumps. In cardiomyocytes, the phosphocreatine circuit allows a substrate channelling between mitochondria and myofibrils. This metabolic compartmentation explains the difficulties of studying energetic metabolism in the beating heart and the lack of correlation between cardiac function and the usual energy parameters. Mitochondria are a potential site of action of anaesthetic agents. Lipophilic local anaesthetics impair cellular energy metabolism and mitochondrial ATP production. Such effects could be associated with toxic effects of these molecules. NMR or near-infrared spectroscopy are non invasive techniques for monitoring energetic metabolism in vivo. Clinical applications are developed for analysing brain, muscle or cardiac function in physiological and pathological conditions.

Adenosine Triphosphate↗
PubMed1998

[Left ventricular diastolic function: physiology, physiopathology, evaluation, therapy, consequences of anesthesia].

With the exception of cardiac surgery, the acute disturbance of the left ventricular diastole occurs mainly in the elderly. Today it represents 30 to 40% of congestive cardiac failures, however with a lower mortality than for acute systolic disturbances. Generally indicated are relaxation anomalies, proto-mesodiastolic mechanism and problems with compliance, an indicator of the pressure/volume diastolic relationship. Invasive techniques remain the standard method. Doppler echocardiography is becoming increasingly important for the assessment of diastolic function. In most cardiopathies, relaxation anomalies occur early, whereas compliance disturbances are mainly associated with advanced cardiac diseases. During anaesthesia, adverse events (auricular fibrillation, hypovolaemia) may worsen a fragile situation. Anaesthetic agents, in particular volatile agents, act on the ventricular diastole. Long-term therapy of diastolic anomalies includes agents amending left ventricular hypertrophy. Emergency therapy has not yet been systematised.

Aged↗
PubMed1998

[Preoperative evaluation of hemorrhagic risk].

Evaluation of bleeding risk before surgery requires both precise knowledge of epidemiological data relating to haemostasis disorders and a true clinical approach to help guide the diagnosis. The patient's individual and familial history is recovered during both the interview with the anaesthesiologist and the clinical examination. Preoperative haemorrhage risk prevalence is 1/40,000 patients in patients with asymptomatic congenital haemostasis disorders with low bleeding and 1/2,000 patients for acquired asymptomatic haemostasis disorders. Deficits in haemostasis factors, i.e., congenital disorders with haemorrhage potential, have an overall prevalence of 1/6,500 patients. Whatever the clinical case, haemorrhage disorders will arise in patients with either congenital or acquired bleeding abnormalities without symptoms. To work in close collaboration with haemobiologists and to request appropriate biological screening tests, it is therefore important to take into account prevalence data according to the surgical environment from which the patient will benefit.

Blood Loss, Surgical↗
PubMed1998

Impact of heterozygosity for the chemokine receptor CCR5 32-bp-deleted allele on plasma virus load and CD4 T lymphocytes in perinatally human immunodeficiency virus-infected children at 8 years of age.

The CCR5 gene encodes one of the major human immunodeficiency virus type 1 (HIV-1) coreceptors. A 32-bp deletion in this gene (delta ccr5) is associated with relative resistance to disease progression in heterozygous HIV-1-infected persons. The effect of this mutation on virologic and immunologic parameters was determined in a cohort of 45 perinatally HIV-1-infected children prospectively followed after 5 years of age. At a median age of 8.3 years, heterozygous children had significantly lower virus load than homozygous children (median, 3.3 vs. 4.1 log copies/mL, P < .009) and higher percentages of CD4 T cells (median, 26% vs. 17%, P < .07). However, there was no discernible influence of the CCR5 genotype on the percentages of CD8 T cells (P < .27) or on HIV-specific cytotoxic T lymphocyte activities (P < .65). There was a trend for lower rates of progression to AIDS (CDC stage C) in heterozygous children. These data confirm a major role for the CCR5 coreceptor in HIV-1 pathogenesis in children.

Acquired Immunodeficiency Syndrome↗
PubMed1996

[A study of practice patterns of albumin administration in surgical patients by anesthetists].

The establishment of guidelines has to take into account the current practice patterns. For the preparation of the consensus conference organized by the French Society of Anesthesia and intensive care (SFAR) on the prescription of albumin, an interview with a questionnaire was undertaken in order to assess the practice patterns of anaesthetists during the perioperative period. A group of 498 anaesthetists were interviewed during a congress. Two out of three prescribe albumin. In case of haemorrhage, the decision to administer albumin depends on the limits for using other colloids (for 65% of the responders), the amount of blood loss (46%) and albuminaemia (for only 26%). In other cases, albumin is mainly administered in the burn patient and for recurring ascite; albuminaemia is a decision criterion for one anesthetist out of two. About 25% of them use a 20% concentration, another 25% of them a 4% concentration and the remaining 50% use both concentrations. Adverse effects have been seen in less than 5% of the responders. These data have been presented at the consensus conference and can also be used for the assessment of the impact of the guidelines after their publication.

Adult↗
PubMed1996

Reduction in requirements for allogeneic blood products: nonpharmacologic methods.

BACKGROUND: Various strategies have been proposed to decrease bleeding and allogeneic transfusion requirements during and after cardiac operations. This article attempts to document the usefulness, or lack thereof, of the nonpharmacologic methods available in clinical practice. METHODS: Blood conservation methods were reviewed in chronologic order, as they become available to patients during the perisurgical period. The literature in support of or against each strategy was reexamined critically. RESULTS: Avoidance of preoperative anemia and adherence to published guidelines for the practice of transfusion are of paramount importance. Intraoperatively, tolerance of low hemoglobin concentrations and use of autologous blood (predonated or harvested before bypass) will reduce allogeneic transfusions. The usefulness of plateletpheresis and retransfusion of shed mediastinal fluid remains controversial. Intraoperatively and postoperatively, maintenance of normothermia contributes to improved hemostasis. CONCLUSIONS: Several approaches have been shown to be effective. An efficient combination of methods can reduce, and sometimes abolish, the need for allogeneic blood products after cardiac operations, inasmuch as all those involved in the care of cardiac surgical patients adhere thoughtfully to existing transfusion guidelines.

Animals↗
PubMed1996

Extracorporeal circulation, hemocompatibility, and biomaterials.

BACKGROUND: Performance of a majority of cardiac surgical procedures requires the use of extracorporeal circulation. Contact of the patients' blood with the nonendothelial surface of the cardiopulmonary bypass circuit is responsible for several, potentially harmful systemic reactions. METHODS: The patients' response to extracorporeal circulation is reviewed briefly. The interactions between patient and circuit are discussed not only as they relate to blood-material contact, but also from a mechanical and rheologic standpoint. The theoretic benefits of the newer, more hemocompatible materials are presented, along with a review of published clinical experience with heparinized cardiopulmonary bypass circuits. RESULTS: The response to extracorporeal circulation extends far beyond a simple derangement of hemostasis. This inflammatory response is strongly influenced by the rheologic design of the circuit and by the physical and chemical properties of the surface. Heparinized circuits decrease inflammation, but the clinical benefits of this reduction remain unclear, except for extended cardiopulmonary support. The safe use of these circuits requires full heparinization and does not reduce allogeneic transfusions. CONCLUSIONS: Clinicians are still in the search of the ideal material and the ideal extracorporeal circuit design. Newer, heparinized materials offer real but limited clinical benefits.

Biocompatible Materials↗
PubMed1996

[Blood transfusion in surgery: can it still be reduced by human recombinant erythropoietin?].

New agents such as recombinant human erythropoietin (rHu EPO) modify conventional transfusionnal strategies. For accurate indications, such as, anaemia associated with chronic renal failure, cancer or cardiac disease, the preoperative prescription of rHu EPO may reduce transfusion requirements. rHu EPO may also be associated with pre-deposit transfusion in patients with anaemia before blood donation, when the transfusion needs are high, or the period for blood pre-deposit donation shortened. Postoperatively rHu EPO is only efficient if it is administered for a prolonged period; this condition limits its indications and value because of its high cost.

Aprotinin↗
PubMed1996

Rheological properties of commonly used plasma substitutes during preoperative normovolaemic acute haemodilution.

Preoperative normovolaemic acute haemodilution (PNAH) is used to reduce major blood loss during elective surgery. Considerable attention has been paid to colloid osmotic pressure, index of diffusibility and intravascular half-life of the currently available substitutes, but there is little information on their rheological properties from in vivo studies. Forty patients undergoing elective aortic reconstruction were given 4% human albumin (HA), 3.5% dextran 40 (Dxt 40), 6% dextran 60 (Dxt 60), 6% hydroxyethylstarch 200 (HES) or modified fluid gelatin (Gel) during PNAH to produce a packed cell volume (PCV) of approximately 30%. Mean volumes of more than 1000 ml were infused. Blood samples were obtained before infusion, immediately after, and 1.5 h after the end of haemodilution. The following variables were measured: PCV, plasma viscosity, whole blood viscosity at measured and corrected PCV (0.45), and erythrocyte aggregation. Haemodynamic and metabolic variables were determined at the same time. The five substitutes had very different effects on red blood cell aggregation and low shear rate viscosity at corrected PCV. Red blood cell aggregation was reduced in the presence of HA, Dxt 40, but was increased moderately to markedly in the presence of the other substitutes in the following order: HES < Dxt 60 < Gel. The influence of the rheological conditions on tissue oxygenation was assessed by measuring the concentration of lactic acid; this was unchanged after PNAH with HA or Dxt 40, but was increased in the presence of HES, Dxt 60 or Gel.

Adult↗
PubMed1996

Memory cytotoxic T lymphocyte responses in human immunodeficiency virus type 1 (HIV-1)-negative volunteers immunized with a recombinant canarypox expressing gp 160 of HIV-1 and boosted with a recombinant gp160.

A vaccine against human immunodeficiency virus (HIV) should induce virus-specific cytotoxic T lymphocyte (CTL) activity. Immunization of uninfected volunteers with a canarypox virus expressing HIV envelope was carried out in a phase I trial. Two injections of canarypox expressing HIV-1MN gp 160 (months 0 and 1) were followed by two boosts of recombinant envelope protein (months 3 and 6). HIV envelope-specific CTL were detected in peripheral blood mononuclear cells stimulated with autologous HIV-1-infected blast cells. T cell lines were obtained from 18 of 20 donors: CTL were detected at least once following immunization in 7 (39%) of these 18. This activity was mediated by major histocompatibility complex class I-restricted CD3+CD8+ T cells. For two subjects, this activity was still present 2 years after the initial immunization. The CTL responses with this prime-boost regimen are the best observed with any HIV vaccine tested in humans.

AIDS Vaccines↗
PubMed1996

[Conditions of practice of upper digestive endoscopy in ambulatory care. Results of a national survey (I)].

OBJECTIVES: The aim of the study was to describe the usual conditions of practice of esophagogastroscopy in ambulatory care by French gastroenterologists. METHODS: During a week, a questionnaire was filled out for each esophagogastroscopy performed in ambulatory or day care. RESULTS: Seven hundred and thirty nine gastroenterologists participated in the study (25.9% of French gastroenterologists) and enrolled 4585 patients. Intra-venous sedation was performed in 36.6% of endoscopic examinations, with diazepam (17.8%), midazolam (41.7%), propofol (14.9%), diazepam and propofol (2.1%) or midazolam and propofol (23.5%). A morphinomimetic was associated in 58.6% of cases. Monitoring equipment of endoscopy units was: aspiration (58.6%), pulse oxymeter (41.6%), electrocardiographic monitoring (37.7%). Recommendations about follow-up after ambulatory anaesthesia were not implemented in 7.3% of examinations with anaesthesia (patient discharged alone). Seventeen minor adverse events were recorded. CONCLUSION: The study underlines variability of practice, mainly about use of sedation, monitoring and follow-up of patients during esophagogastroscopy performed in ambulatory care in France. An improvement in quality of endoscopy practice is likely.

Adult↗
PubMed1996

[Patient's opinion following an upper digestive endoscopy in ambulatory care. Results of a national survey (II)].

OBJECTIVES: The aim of the study was to evaluate patient satisfaction after esophagogastroscopy performed in ambulatory care and to correlate it with conditions of usual practice. METHODS: Study was proposed to the French gastroenterologists. During a week, 2 questionnaires were filled out for each esophagogastroscopy performed in ambulatory care: one recorded conditions of examination and one was independently filled out by the patient one day after endoscopy. RESULTS: Seven hundred and thirty nine gastroenterologists and 4,585 patients participated in the study. Among the patients, 3,758 (82%) filled out the questionnaire. Sedation was performed in 36.6% of cases. Subsequent endoscopy would be accepted by 79.3% of patients in the same conditions. Acceptance was significantly better with use of sedation and use of propofol. Without sedation, independent factors associated with a better acceptance were: male gender, absence of habitual benzodiazepine medication, endoscopy performed in private practice or private hospitals, smaller size of endoscope. CONCLUSION: This study underlines factors associated with a good acceptance of esophagogastroscopy without sedation and could help to improve decision-making regarding use of sedation.

Adult↗