Accepter le prélèvement d'organes sur patients DDAC III

Le prélèvement d'organes, en France, s'inscrit aujourd'hui dans un cadre très spécifique, celui défini par la classification de Maastricht, établie en 1995 lors d'une Conférence internationale de consensus. Cette classification distingue les personnes ayant fait un arrêt cardiaque en présence (classe II) ou non (classe I) de secours qualifiés, les personnes pour lesquelles la mort survient dans les suites d'une décision d'arrêt de traitements en réanimation (classe III) et enfin les personnes chez qui survient un arrêt cardiaque inopiné lors de la réanimation d'un donneur en mort encéphalique (classe IV). En France, seuls sont autorisés actuellement les prélèvement de reins et de foie chez les personnes des catégories I, II et IV. La question d'une extension des conditions du prélèvement d'organes aux patients de la catégorie III de la classification de Maastricht (DDAC III) se trouve régulièrement soulevée en France. L'évolution du patient vers la mort dépendant, dans le cas de ces patients, d'une décision et d'un processus intentionnel, le prélèvement d'organes pose des problèmes, notamment éthiques, spécifiques. Dans le texte qui suit, nous souhaitons prendre le contre-pied d'une tendance récurrente du débat public consistant à éviter de « questionner l'éthique lorsque l'on pense que ce questionnement pourrait avoir un effet négatif sur ce qu'on essaie de mettre en place » (Gruat 2010, p. 11). Pour entrer dans le vif de cette réflexion, nous dégagerons de façon systématique les problèmes éthiques afférents à la législation de l'éligibilité au prélèvement d'organes des donneurs DDAC III, à partir de sa mise en perspective avec les prélèvements d'organes sur les patients en état de mort encéphalique (EME) et DDAC I et II. Après avoir exposé les pratiques existant dans le domaine hors de nos frontières, nous explorerons les conditions cliniques du prélèvement d'organes sur patients DDAC III, nous exposerons les conflits d'intérêt que peut induire cette pratique, nous tenterons d'évaluer les coûts et bénéfices de sa législation en France pour proposer enfin des orientations susceptibles de structurer l'introduction de cette pratique sur le territoire national

Décider la mort et prélever les organes : la question de l'extension des conditions du prélèvement d'organes

International audienceSocial and political discourse still emphasizes the “shortage” of transplantable organs. In this international and national context, broadening the pool of donors is at stake. Addressing the specific case of withdrawing life-sustaining treatments, the paper will analyse the social and moral consequences of this extension and the moral dilemmas that it creates. We will also underline how the indeterminacy of fundamental norms gives rise to divergent and morally controversial practices in Western countries. Finally we will highlight the kind of normative evolution prompted by such new medical practices.La référence à la pénurie d'organes est un lieu commun du discours politique et social associé au don. Dans ce contexte, se pose la question d'une extension possible des conditions d'inclusion des patients parmi les donneurs d'organes. Nous analyserons ici, dans le cas spécifique des patients pour lesquels un arrêt des thérapeutiques est décidé, les conséquences morales et sociales ainsi que les dilemmes moraux suscités par une telle extension. Nous montrerons notamment que l'indétermination des normes de référence autorise des pratiques divergentes et moralement contestées au sein des pays occidentaux. Il s'agira également de souligner les formes d'aménagement normatif induites par cette évolution de la pratique médicale

Clinical review: Prognostic value of magnetic resonance imaging in acute brain injury and coma

Progress in management of critically ill neurological patients has led to improved survival rates. However, severe residual neurological impairment, such as persistent coma, occurs in some survivors. This raises concerns about whether it is ethically appropriate to apply aggressive care routinely, which is also associated with burdensome long-term management costs. Adapting the management approach based on long-term neurological prognosis represents a major challenge to intensive care. Magnetic resonance imaging (MRI) can show brain lesions that are not visible by computed tomography, including early cytotoxic oedema after ischaemic stroke, diffuse axonal injury after traumatic brain injury and cortical laminar necrosis after cardiac arrest. Thus, MRI increases the accuracy of neurological diagnosis in critically ill patients. In addition, there is some evidence that MRI may have potential in terms of predicting outcome. Following a brief description of the sequences used, this review focuses on the prognostic value of MRI in patients with traumatic brain injury, anoxic/hypoxic encephalopathy and stroke. Finally, the roles played by the main anatomical structures involved in arousal and awareness are discussed and avenues for future research suggested

The ethical and legal aspects of palliative sedation in severely brain-injured patients: a French perspective

To fulfill their crucial duty of relieving suffering in their patients, physicians may have to administer palliative sedation when they implement treatment-limitation decisions such as the withdrawal of life-supporting interventions in patients with poor prognosis chronic severe brain injury. The issue of palliative sedation deserves particular attention in adults with serious brain injuries and in neonates with severe and irreversible brain lesions, who are unable to express pain or to state their wishes. In France, treatment limitation decisions for these patients are left to the physicians. Treatment-limitation decisions are made collegially, based on the presence of irreversible brain lesions responsible for chronic severe disorders of consciousness. Before these decisions are implemented, they are communicated to the relatives. Because the presence and severity of pain cannot be assessed in these patients, palliative analgesia and/or sedation should be administered. However, palliative sedation is a complex strategy that requires safeguards to prevent a drift toward hastening death or performing covert euthanasia. In addition to the law on patients' rights at the end of life passed in France on April 22, 2005, a recent revision of Article 37 of the French code of medical ethics both acknowledges that treatment-limitation decisions and palliative sedation may be required in patients with severe brain injuries and provides legal and ethical safeguards against a shift towards euthanasia. This legislation may hold value as a model for other countries where euthanasia is illegal and for countries such as Belgium and Netherlands where euthanasia is legal but not allowed in patients incapable of asking for euthanasia but in whom a treatment limitation decision has been made

Event related potentials elicited by violations of auditory regularities in patients with impaired consciousness.

International audienceImproving our ability to detect conscious processing in non communicating patients remains a major goal of clinical cognitive neurosciences. In this perspective, several functional brain imaging tools are currently under development. Bedside cognitive event-related potentials (ERPs) derived from the EEG signal are a good candidate to explore consciousness in these patients because: (1) they have an optimal time resolution within the millisecond range able to monitor the stream of consciousness, (2) they are fully non-invasive and relatively cheap, (3) they can be recorded continuously on dedicated individual systems to monitor consciousness and to communicate with patients, (4) and they can be used to enrich patients' autonomy through brain-computer interfaces. We recently designed an original auditory rule extraction ERP test that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. Local violations led to an early response in auditory cortex, independent of attention or the presence of a concurrent visual task, while global violations led to a late and spatially distributed response that was only present when subjects were attentive and aware of the violations. In the present work, we report the results of this test in 65 successive recordings obtained at bedside from 49 non-communicating patients affected with various acute or chronic neurological disorders. At the individual level, we confirm the high specificity of the 'global effect': only conscious patients presented this proposed neural signature of conscious processing. Here, we also describe in details the respective neural responses elicited by violations of local and global auditory regularities, and we report two additional ERP effects related to stimuli expectancy and to task learning, and we discuss their relations to consciousness

Significado do ponto de inflexão inferior da curva pressão-volume em pacientes com insuficiência respiratória aguda: avaliação por tomografia computadorizada

OBJECTIVE: The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point on the lung pressure-volume curve and to compare the effects of positive endexpiratory pressure (PEEP).MATERIALS AND METHODS: Eight patients with and six without a lower inflection point (LIP) underwent a computed tomography performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cmH2O e PEEP2 = LIP + 7 cmH2O, or PEEP1 = 10 cmH2O and PEEP2 = 15 cmH2O in the absence of LIP and, based on the analysis of the lung density histograms, the gas-tissue ratio and the lung areas volumes were calculated (nonaerated, poorly aerated, normally aerated and overdistended volumes).RESULTS: In the ZEEP condition, patients with and without LIP presented similar total lung volume, volume of gas, and volume of tissue, although the percentage ofnormally aerated lung was lower and the percentage of poorly aerated lung was greater in patients with LIP than in patients without it. Lung density histograms ofpatients with LIP showed an unimodal distribution with a peak at 7 Housenfield units (HU), while histograms of patients without LIP had a bimodal distribution, with a first peak at -727 HU, and a second at 27 HU. Lung compliances were lower in patients with LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without LIP.CONCLUSIONS: The evaluation of the pressure-volume curve in patients with acute lung injury allows us to divide them into two groups according to the presence or absence of LIP. This division is associated with the differences in lung morphology and in the responses to PEEP application in terms of alveolar recruitment andoverdistention, the latter being defined as the occurrence of pulmonary parenchyma under -900 HU. In patients with LIP, gas and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolarrecruitment without lung overdistention. In patients without LIP, normally aerated areas coexist with nonareted lung areas and increasing levels of PEEP result in lung overdistention rather than in additional alveolar recruitment.OBJETIVO: O objetivo deste estudo foi avaliar, através de tomografia computadorizada, a morfologia pulmonar em pacientes com lesão pulmonar aguda de acordo com a presença ou ausência de ponto de inflexão inferior (Pinf) nas curvas pressão-volume e comparar os efeitos da pressão expiratória final positiva (PEEP).MATERIAIS E MÉTODOS: Oito pacientes com e seis sem Pinf foram submetidos a tomografias computadorizadas realizadas em zero de pressão expiratória final positiva(ZEEP) e em dois níveis de PEEP: PEEP1 = Pinf+2 cmH2O e PEEP2 = Pinf+7 cmH2O, ou PEEP1 = 10 cmH2O e PEEP2 = 15 cmH2O na ausência de Pinf e, a partir da análise dos histogramas de densidade pulmonares, foram calculados a razão gás-tecido e os volumes pulmonares regionais (volumes não-aerado, pobremente aerado, normalmente aerado e hiperdistendido).RESULTADOS: Os pacientes com e sem Pinf apresentaram, em ZEEP, valores similares de volume pulmonar total e volume de gás e tecido, mas a porcentagem de pulmão normalmente ventilado foi menor e a de pulmão pobremente ventilado maior em pacientes com Pinf do que em pacientes sem Pinf. Os histogramas de densidade pulmonares de pacientes com Pinf mostraram uma distribuição unimodal com um pico em 7 unidades Hounsfield (UH), enquanto os pacientes sem Pinf tinham uma distribuição bimodal com um primeiro pico em -727 UH e um segundo em 27 UH. A complacência do sistema respiratório era menor em pacientes com Pinf, enquanto todos os outros parâmetros cardiorrespiratórios eram similares nosdois grupos. Em ambos os grupos, PEEP induziu recrutamento alveolar, o qual foi associado à hiperdistensão pulmonar apenas nos pacientes sem Pinf.CONCLUSÕES: A avaliação das curvas pressão-volume em portadores de lesão pulmonar aguda permite dividi-los em dois grupos, de acordo com a presença ouausência de ponto de inflexão inferior. Esta divisão associa-se com diferenças na morfologia pulmonar e nas respostas à aplicação de PEEP em termos de recrutamento alveolar e hiperdistensão, definindo-se esta última como a ocorrência de parênquima pulmonar abaixo de -900 UH. Em pacientes com Pinf, gás e tecido estão mais homogeneamente distribuídos no interior dos pulmões, e níveis crescentes de PEEP resultam em recrutamento alveolar adicional sem hiperdistensão. Em pacientes sem Pinf, regiões pulmonares normalmente ventiladas coexistem com regiões não-ventiladas, e a aplicação de PEEP, embora cause recrutamento, acarretatambém hiperdistensão, que aumenta com níveis crescentes de PEEP