Dr. Samuel Harrington, an experienced physician, articulates here in his article entitled "Mission Creep Doesn’t Benefit Patients At The End Of Life" something that I've espoused for a while - advanced medical care at the end of life can be a two-edged sword. While western medicine is a wonderful benefit, it often also turns death from what used to be an event into a multi-year process characterized by loss of mobility, senility, incontinence, pain and suffering.
It is important to make the distinction between killing someone and letting them die - i.e., letting a process that is underway proceed without interference. In cases where a patient has clearly articulated their desire to die, and where there is no reasonable hope of recovery and death appears imminent - it does not seem morally wrong to allows one to die rather than initiating an artificial life support system or prolong the dying process by artificial means.
It's mystifying to me when mature Christians who are elderly and in failing health approach death with a firm resolve to cling to life for as long as absolutely possible with every possible resource available. Figuratively speaking they hang onto this world by their fingernails and have to be dragged into Paradise kicking and screaming. Suicide and euthanasia are morally wrong. But death itself is a release for the believer - as Paul says, it is far better to depart this fallen world and be with Christ (Phil 1:23). I believe part of the problem is the reluctance of the church to theologically deal with the topic of death head-on, instead of leaving it as a White Elephant that everyone knows about, but nobody talks about. I can understand unbelievers fearing death and availing themselves of every last possible medical option and grasping at the last straw, no matter how painful or expensive, to "buy" a few more moments.
For those that exercise repentant faith, Christ delivers us from the fear of death (Heb 2:14-15) and God astonishingly views our deaths as "precious" (Ps 116:15).
The ESV Study Bible provides pertinent theological analysis for difficult end-of-life issues:
The End of Life
As a result of the fall, physical death is inevitable for all people (Rom. 5:12–14; 1 Cor. 15:21–22). The process of dying is frequently accompanied by illness, suffering, and pain. Euthanasia is one way people have sought to eliminate end-of-life suffering. Euthanasia occurs when a terminally ill person dies as a result of a deliberate act of commission (active euthanasia) or omission (passive euthanasia) by another person seeking to hasten the ill person’s death in order to end his or her suffering. The person who is ill may have given informed consent (voluntary), may have withheld consent (involuntary), or may have been incompetent to give consent (non-voluntary).
Active euthanasia is clearly prohibited by the sixth commandment, regardless of the ill person’s request. This moral principle is seen in the case of King Saul. Fatally injured, Saul commanded his armor-bearer to kill him so that he would not suffer humiliation from his enemies. His armor-bearer refused, however (1 Sam. 31:3–5). In contrast, when the Amalekite brought news of Saul’s death to David, claiming that he had killed Saul at the king’s own request in order to end his misery, David executed the Amalekite for taking Saul’s life (2 Sam. 1:1–16).
Passive euthanasia involves withholding either natural life-sustaining means (e.g., food, water, air) or unnatural life-sustaining means (e.g., life-supporting machines) in order to cause death and thus end suffering. Many Christian ethicists believe that withholding natural means of life-sustenance from helpless patients is comparable to withholding the same means from an infant, as it will directly cause death. This act of negligence leading to death is thus also viewed as being prohibited by the sixth commandment. A somewhat different question is whether doctors are ethically able to withhold futile treatments that do not improve the prospect of recovery and only prolong the process of dying when death is imminent and inevitable. In such cases, according to some Christian ethicists, it is morally acceptable to allow such a person to die, though whenever there is a reasonable chance of recovery or improvement of the quality of life this should be pursued.
The bottom line: Despite Silicon Valley's infatuation with immortality, barring the return of Christ, death is inevitable for everyone of us without exception. But Christians stand alone in the glorious truth that death has no hold over us. If you're a Christian, exercise your end-of-life choices wisely; you have options.