When patients express a certain degree of symptom severity, they themselves should indicate whether their suffering is severe enough to justify treatment by sedation.
Suffering and distress are subjective criteria and logically only patients can determine the suffering intolerable. If the patient is unable to give informed consent for treatment and cannot express the degree of discomfort, a proxy judgment by family members and medical staff should assess the level of suffering by the patient.
All possible treatment has failed, or it is estimated that no methods are available for palliation within the time frame and the risk/benefit ratio the patient can tolerate.
Suffering occurs when an impending destruction of the person is perceived; it continues until the threat of disintegration has passed or until the integrity of the person can be restored in some other manner.
Most generally, suffering can be defined as the state of severe distress associated with events that threaten the intactness of the person.