Admission of a patient in the Intensive Care Unit (ICU) is justified when the critical situation can be reverted or relieved. In spite of this, there is high mortality in the ICU in regard to other hospital departments. End-of-life treatment of critical patients and attention to the needs of their relatives is far from being adequate for several reasons: society denies or hides the death, it is very difficult to predict it accurately, treatment is frequently fragmented between different specialists and there is insufficient palliative medicine training, including communication skills. There are frequent conflicts related to the decisions made regarding the critical patients who are in the end of their life, above all, with the limitation of life-sustaining treatments. Most are conflicts of values between the different parties involved: the patient, his relatives and/or representatives, health professionals, and the institution. The SEMICYUC Working Group of Bioethics elaborates these Recommendations of treatment at the end of the life of the critical patient in order to contribute to the improvement of our daily practice in such a difficult field. After analyzing the role of the agents involved in decision making (patient, familiar, professional, and health care institutions), of the ethical and legal foundations of withholding and withdrawal of treatments, guidelines regarding sedation in the end of the life and withdrawal of mechanical ventilation are recommended. The role of advance directives in intensive medicine is clarified and a written form that reflects the decisions made is proposed.
A new technique is presented for solving the problem of enforcing control limits in power flow studies. As an added benefit, it greatly increases the achievable precision at nose points. The method is exemplified for the case of Mvar limits in generators regulating voltage on both local and remote buses. Based on the framework of the Holomorphic Embedding Loadflow Method (HELM), it provides a rigorous solution to this fundamental problem by framing it in terms of optimization. A novel Lagrangian formulation of power-flow, which is exact for lossless networks, leads to a natural physics-based minimization criterion that yields the correct solution. For networks with small losses, as is the case in transmission, the AC power flow problem cannot be framed exactly in terms of optimization, but the criterion still retains its ability to select the correct solution. This foundation then provides a way to design a HELM scheme to solve for the minimizing solution. Although the use of barrier functions evokes interior point optimization, this method, like HELM, is based on the analytic continuation of a germ (of a particular branch) of the algebraic curve representing the solutions of the system. In this case, since the constraint equations given by limits result in an unavoidable singularity at s = 1, direct analytic continuation by means of standard Padé approximation is fraught with numerical instabilities. This has been overcome by means of a new analytic continuation procedure, denominated Padé-Weierstrass, that exploits the covariant nature of the power flow equations under certain changes of variables. One colateral benefit of this procedure is that it can also be used when limits are not being enforced, in order to increase the achievable numerical precision in highly stressed cases.
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