Every year, millions of people with serious diseases, as well as their loved ones, are confronted with decisions relating to the quality of the time that remains to be lived. The quality of the end of life may be severely altered by pain or other distressing symptoms. Physicians have a duty to relieve suffering in their patients. However, in most countries, they are not allowed to intentionally shorten life, although treatments given to relieve suffering are permitted even if they are also expected to shorten life (double-effect principle). A major challenge faced by physicians is to honour their patients' wishes and values and to help them safeguard their dignity and peace at the end of life.

Some seriously ill patients, such as those with severe brain injuries, are unable to communicate their suffering. In these patients, the effectiveness of palliative care cannot be assessed: the possibility of persistent suffering cannot be ruled out 1. There is a wide consensus that palliative sedation is appropriate as a last resort in this situation 2. However, palliative sedation is a complex intervention that is closer to physician-assisted suicide and voluntary active euthanasia than is ordinarily acknowledged. Safeguards are needed whenever a medical intervention may hasten death. Legislation stating which practices are permissible would reassure the numerous patients who fear a "bad" death and would improve practice uniformity among physicians 3. The French law on patients' rights and the end of life passed on April 22, 2005 (Law n° 2005-370, known as the Leonetti law) 4 indicates that patients should be allowed to die as comfortably and peacefully as possible but should not be made to die. This law reflects the evolution of French medical thinking about the best means of protecting patients' well-being and dignity while refraining from intentionally causing death. It has also led to further ethical discussions, most notably about palliative sedation after treatment-limitation decisions in patients with severe brain injuries. Thus, a committee evaluated the Leonetti law and revised the article of the French Code of Medical Ethics relating to the relief of suffering 5. These issues were specifically addressed during multiple hearings in the French Parliament 6

Severely brain-injured patients who are unable to communicate are at high risk for suffering. More specifically, the ability to perceive pain has been well documented in patients who are in a minimally conscious state 178, in whom suffering is very difficult to assess 9. In these patients, when treatment-limitation decisions are made based on the clinical findings and results of investigations, the potential appropriateness of palliative sedation is an extremely relevant issue 10. The possible need for palliative sedation deserves special attention when patients are taken off mechanical ventilation and either extubated or decannulated, as well as when nutrition and hydration are stopped in patients with chronic consciousness disorders 11. Currently available scientific knowledge usually does not allow the distinction between unconscious nervous reactions and pain perception in most such patients 1, and the possibility of "unconscious pain" has been raised 12, generating considerable interest in the issue of palliative sedation. The goal of palliative sedation started before or at the time life-supporting treatments are withdrawn is to eliminate pain perception and neurological responses that might result from treatment withdrawal. In this situation, palliative sedation is a gesture of humanity towards both the patient and the family members, whose primary request is that their loved one does not suffer. Palliative sedation can thus represent an appropriate form of palliative care.

The concept of sedation does not have a precise medical content. Literally, "to sedate" means to alleviate suffering. The definition of palliative sedation remains vividly debated, particularly regarding the presence or absence of an intention to hasten death 13. Palliative sedation is defined by some authors as the use of drugs to put the patient in a state of comfort and unawareness of his or her situation without intentionally hastening death 14. The level of palliative sedation varies with the drugs used, and the above-mentioned definition covers the continuum from simply keeping the patient asleep to inducing an artificial coma. Inducing an artificial coma, which can be described as major sedation, may be indispensable in the event of treatment limitations such as the withdrawal of life-supporting interventions. Major palliative sedation has complex links with treatment withdrawal, as underlined in the parliamentary report on the evaluation of the Leonetti law (p. 204-216) 15. (Rapport de la mission d'évaluation de la loi n° 2005-370 du 22 avril 2005). Palliative sedation has been criticized as being a slow, disguised, and socially acceptable form of euthanasia 161718192021. Other authors endorse the "double effect" principle 142223, acknowledging that a shorter time to death is a possible side effect of palliative care 2425.

The main difference between physician-assisted suicide or euthanasia and palliative sedation lies in the presence or absence of an intention to hasten death and the precise knowledge of the patient's wishes 23. The strict definition of euthanasia retained by the Dutch and Belgian laws is "the intentional taking of someone's life by another, at his request". In palliative sedation, the drug dosages are increased only until the suffering is alleviated. The intention in palliative sedation is to fully protect the patient from pain. There is no intention to hasten death. In addition, palliative sedation is reversible, whereas death caused by an overdose of sedatives is not 26. Allowing a patient to die at some point may constitute a practical necessity if medical care is to be given successfully, but the same is not true of physician-assisted suicide 27. Moreover, support for palliative sedation is widespread among internists. Most physicians who view palliative sedation favourably do not support physician-assisted suicide and feel that these two practices are on different sides of the line separating the ethical from the unethical 28.

The issue of end-of-life care was long neglected by French law. Healthcare providers could rely only on the French code of medical ethics, which required that they "refrain from any unreasonable obstinacy in investigations or treatments" while reminding them solemnly that they had "no right to cause death intentionally" (Article 38, Additional file 1). This last provision was the translation to the medical ethics field of Penal Code laws prohibiting homicide. The French Code of Medical Ethics is part of the Public Health Code and has the force of law.

In addition to requiring that healthcare providers respect patients' decisions to stop treatment, the Leonetti law allows physicians to make treatment withdrawal decisions for patients who are "unable to express their wishes" (Articles L. 1111-4 and L. 1111-13), as a means of avoiding unreasonable obstinacy, provided the decisions are preceded by consultation of all medical team members, any advance directives written by the patient, and the close relatives, and are considered appropriate by an external consultant 4. French intensive care societies view tube feeding as a life-sustaining treatment whose withdrawal is advisable when all treatments except comfort care are stopped.

When a decision is made to withdraw treatments intended to prolong life, the physician must bear in mind that the law authorizes the withdrawal of such treatments only with the condition that any additional suffering potentially caused by treatment withdrawal will be completely eliminated by palliative care.

A parliamentary mission known as the Leonetti Mission was appointed by the French government to assess the implementation of the 2005 law. It released its conclusions in late 2008. The Leonetti Mission called into question the adequacy of palliative care in severely brain-injured patients with treatment-limitation decisions taken in a collegial manner. In some of these patients, pain is not readily assessable and the existence of pain cannot be ruled out. In 2006 in France, a young man in a vegetative state whose gastric tube was withdrawn without preliminary sedation died only 6 days later after experiencing multiple seizures that caused severe distress to the family. This case, together with the Leonetti Mission conclusions, promoted a revision of Article 37 of the French code of medical ethics. A paragraph was added to this article to require the use of sedation and/or analgesia to eliminate any suffering possibly caused by treatment withdrawal in patients with brain damage precluding a reliable evaluation of pain perception. The revision of Article 37 was released in January 2010 (Additional file 2). The use of sedation/analgesia under the conditions of transparency and collegiality required by the law will now ensure that patients do not suffer, particularly those in neurointensive care units or neonatology wards. On the legal level, this new requirement confirms the right of patients to palliative care, as stated by article L. 1110-9 of the Public Health Code. It reminds physicians of their duty to respect the patient's right to receive palliative care, including major palliative sedation when considered proportionate to the patient's potential suffering.

Situations involving severe brain injury are not all identical. Current legislation in France is based on the principle of proportionality. Physicians must choose among available treatments those that are proportionate to the patient's condition. Thus, useless treatments must be stopped and palliative strategies selected according to the patient's needs. Among these strategies, deep palliative sedation is allowed by the revised law to eliminate potential suffering in patients whose predicted neurological outcome dictates the withdrawal of life-supporting treatments. The physician must select the level of sedation that is proportionate to the suffering endured, or possibly endured, by each individual patient. In patients with severe brain injuries, the presence and intensity of the pain cannot be reliably assessed and, consequently, the proportionate amount of sedation cannot be determined. The French Board of Physicians has stated that "the goal is to provide patients with severe brain injuries precluding a reliable evaluation of suffering with the same level of relief as that received by patients who are able to communicate." The law requires documentation in the medical files of all the information needed to make the decision. In other words, the decision must be substantiated.

The Leonetti Mission recommended that the Code of Medical Ethics specify the sedation modalities that must accompany the withdrawal of life-supporting treatments in patients whose pain perceptions cannot be assessed. The principle of proportionality of sedation is deemed to protect against the use of sedation with the intention of causing death 29.

The hospital staff may sometimes decide to use sedation because no palliative care team is available to ensure analgesia and to accompany the dying patient. However, deep sedation is in no case a substitute for palliative care, i.e. an easy solution intended to compensate to some extent for the absence of palliative care. Using deep sedation as a substitute for palliative care disregards the principle of proportionality on which the Leonetti law is based.

Transparency of the decision-making process, collegial decision making, information of the relatives, and documentation of the entire decision-making process in the medical files are legal requirements that constitute safeguards against the inappropriate use of palliative sedation. The support and guidance provided by the healthcare team to the family are invaluable in helping the family to accept the last phase of their loved one's life.

In recent years, progress has been made in defining the components of high-quality care for patients with severe consciousness disorders. These components include palliative care to maximize quality of life as an integral part of the overall treatment plan, as well as clarity about the availability of last-resort options when the presence and intensity of pain cannot be assessed.

Indeed, there is a widespread consensus that high-quality palliative care may fail to provide adequate relief. In this situation, good practice requires that palliative care include a consideration of palliative sedation 43. The existence of brain damage that precludes an assessment of pain produces a similar situation. The French Code of medical ethics specifies that providing analgesia and sedation as needed is a duty when treatment-limitation decisions are implemented in unconscious adults or in neonates. The purpose of recent French legislation is to make palliative sedation available as a last resort to all patients in France, as part of standard care.

Defining palliative sedation for non-communicating or minimally conscious patients is crucial to ensure that a satisfactory balance is achieved between respecting the fundamental right of patients to have their suffering relieved and protecting patients against a shift towards euthanasia.

The end of life should not be synonymous with sedation. Physicians must resist requests for a scheduled death. Palliative sedation should be used only for the right reasons, after a careful decision-making process and in a medically and technically appropriate way 31. We must bear in mind that palliative sedation can easily shift to slow covert euthanasia 44. We must continue the time-honoured practice of refraining from deliberately terminating human life 31. The rule of proportionality of the sedation to the patient's condition and symptoms affords a safeguard against intentionally causing or hastening death.

The recent revision of Article 37 of the French code of medical ethics relating to relief of pain attempts to address all concerns about the possible hazards associated with palliative sedation. In the near future, surveys will be needed to assess compliance with this revised article in everyday practice.

The authors declare that they have no competing interests.

LP initiated the article and made substantial revisions to the earlier draft. AB did the bibliographic research and wrote the first draft and the final version of the manuscript. FC, GA and PMM read the first version and contributed editorial and critical modifications. All authors read and approved the final manuscript.

Antoine Baumann, MD, DESA, is a staff anesthesiologist and intensivist in the Department of Anesthesiology and Surgical Intensive Care of Nancy University Hospital (France) and member of the ethics reflection committee of the hospital. Working in Neurosurgical intensive care unit and middle care unit, he his every day confronted by decision and care in severely brain-injured patients.