Clinical ethics involves identifying, analyzing, and resolving moral problems that arise while caring for patients (8). Four prima facie principles encompass most ethical dilemmas encountered while caring for patients. Beneficence is the duty to act in the best interests of the patient. Non-maleficence is the duty to avoid harming patients (including not providing ineffective treatments). Respect for patient autonomy is the duty to respect the patient's rights to bodily integrity and self-determination. Justice is the duty to treat the patient fairly. Sometimes these principles conflict with each other. For example, contemplating a patient's request to withdrawal MCS may conflict with the clinician's desire to help, and avoid harming, the patient (8, 9).

A life-sustaining treatment is one that prolongs life without which patient death would likely occur. There are many LSTs including mechanical ventilation, hemodialysis, artificial nutrition and hydration, MCS, and others. Ethically and legally, withholding and withdrawing treatment are equivalent (10, 11). Carrying out a request to withhold or withdraw any treatment, including LST, is predicated on informed consent and, specifically, informed refusal. The principle of respect for patient autonomy is the basis of informed consent and refusal. Patient autonomy is optimized when the patient understands his/her diagnosis and treatment options, including no treatment, and participates fully in decision-making regarding these options. The clinician is obligated to ensure the patient is informed regarding his/her diagnosis and treatment options. Components of informed consent and refusal include information (typically the amount of information a reasonable patient needs), patient voluntariness, and patient decisional capacity. Decisional capacity refers to the patient's ability to make healthcare-related decisions. Requirements for decisional capacity include being able to grasp pertinent information, understand the clinical situation at hand, rationally manipulate information, make a decision consistent with one's own healthcare-related values, goals, and preferences, and communicate a decision. The clinician should not presume decisional incapacity if the patient makes a decision contrary to the clinician's recommendation. Rather, capacity should be presumed. Nonetheless, evidence for capacity varies according to the complexity of the decision to be made; i.e., the more complex the decision to be made, the higher the level of capacity required to make it. Notably, in the U.S., “competence” is a legal term and determined by courts. Most patients who lose decisional capacity due to illness are not declared incompetent by courts. Rather, in these situations, clinicians determine decisional capacity. With rare exceptions (e.g., an emergency), the clinician should not treat the patient without informed consent. The patient has the right to accept a proposed treatment, proceed with another option, or refuse treatment altogether (10, 11).

In the U.S., codes of ethics are clear regarding the patient's right to make healthcare-related decisions. Not only does the patient have the right to refuse any treatment, he/she also has the right to refuse any ongoing previously consented treatment, including LST, if the patient concludes the burdens of the treatment outweigh the benefits and is inconsistent with his/her healthcare-related values, goals, and preferences. While the effectiveness of a treatment (e.g., based on clinical trials) is the purview of the clinician, the burdens and benefits of a treatment are the purview of the patient. Whatever the clinician's intent, commencing or continuing a treatment the patient does not want is battery. The clinician's duty is to ensure the patient's refusal of, or request to withdraw, a treatment is informed (10–13).

U.S. courts have consistently ruled that, based on rights to bodily integrity and self-determination, the patient has the right to make healthcare-related decisions including refusing LST before it is started and requesting its withdrawal after it is started. The precedents established by landmark U.S. court cases include: (a) the right to refuse, or request the withdrawal of, any treatment including LST; (b) there is no difference between withholding a treatment and withdrawing an ongoing treatment; (c) the patient refusing, or requesting the withdrawal of, LST need not be terminally ill; (d) carrying out an informed refusal of, or request to withdraw, LST is not a form of physician-assisted suicide or euthanasia; (e) death that follows carrying out an informed refusal of, or request to withdraw, LST is due to the underlying disease; (f) the patient without decisional capacity has the same rights through a surrogate decision-maker (see below); (g) no treatment has unique moral status in that the treatment must be started or, once started, must be continued; and (h) there is no right to physician-assisted suicide or euthanasia (10, 14–16). Parenthetically, consistent with the “rule of double effect,” clinicians should provide treatment to alleviate suffering even if the treatment has the potential to hasten patient death. Doing so, if the intent is to relieve suffering, is ethical, legal, and not a form of physician-assisted suicide or euthanasia (17–20) (Table 1).

In the U.S., a court-appointed guardian makes medical decisions for the patient declared incompetent by the court. For the patient who lacks decisional capacity due to medical illness, clinicians must rely on a surrogate. If the patient has an advance directive (AD), and the AD identifies a surrogate, that person should make decisions for the patient (10, 11). An AD is a legal document completed by a patient that provides instructions for future care in the event the patient loses decisional capacity. In general, there are three types of ADs: health care power of attorney, living will, and combined ADs. In a health care power of attorney, the patient designates another person as his/her surrogate decision-maker. In a living will, the patient provides instructions for future care (e.g., LST) and circumstances (e.g., terminal illness). The patient can also indicate his/her healthcare-related values, goals, and preferences, what to do if pregnant, and organ donation. The combined AD has features of both a healthcare power of attorney and living will. Laws regarding ADs vary by U.S. state, but all 50 states regard the AD as an extension of the patient when he/she was fully autonomous (21).

The surrogate should make decisions based on the contents of the patient's AD. In addition, the clinician should adhere to the contents of the patient's AD, unless the instructions are unreasonable (e.g., impractical, illegal, etc.). There are benefits of having an AD. For example, a systematic review of 45 observational studies showed that patients who had ADs experienced reduced rate of hospitalization, reduced risk for dying in hospitals, reduced use of LSTs, and increased used of hospice and palliative care (22). Also, ADs coupled with advance care planning, may reduce moral distress among surrogates and clinicians when making difficult decisions by providing insights regarding the patient's healthcare-related values, goals, and preferences (i.e., what the patient would decide if he/she had decisional capacity).

Unfortunately, only about one-quarter of U.S. adults have ADs (21, 23). However, most U.S. states have laws which specify a hierarchy of surrogate decision-making for patients who lack decisional capacity and don't have ADs. Typically, a spouse, child, or other first-degree relative is the surrogate. Nonetheless, there is variability among U.S. states regarding these hierarchies (23).

When making decisions for the patient who lacks decisional capacity, the surrogate should adhere to the contents and instructions in the patient's AD, if extant. The surrogate should make decisions based on “substituted judgment”; i.e., based on the patient's, not the surrogate's, healthcare-related values, goals, and preferences. To optimize “substituted judgement,” a useful question to ask the surrogate is, “If (the patient) could wake up for 15 minutes, understand [his/her] current medical situation completely, and then had to go back into it, what would [he/she] tell us to do? (24)” If the patient's healthcare-related values, goals, and preferences are unknown, the surrogate should base his/her decisions on the “best interests” of the patient (e.g., quality of life). In the rare instance in which the clinician and/or care team perceive the surrogate is not making decisions for the patient based on substituted judgment or best interests, meeting with the surrogate to explore these concerns and ethics consultation should be considered (11).

Notably, although no treatment has unique moral status, some U.S. states necessitate high levels of evidence of the patient's wishes regarding artificial hydration and nutrition (e.g., written documentation in an AD) before carrying out a surrogate's request for it to be withdrawn (10).

The American Medical Association Code of Ethics states, “Physicians are not ethically obligated to deliver care that, in their best professional judgment, will not have a reasonable chance of benefitting their patients” (11 p16). A clinician and his/her care team may conclude ongoing LST will not result in achieving clinical goals such as restoration of consciousness and discharge to home (i.e., medically ineffective). In these circumstances, the team should seek to understand the patient's healthcare-related values, goals, and preferences, obtain input from the surrogate if necessary, provide prognostic information, and take into account the intent of the LST, which the AMA declares “should not be to prolong the dying process without benefit to the patient…” (11 p18). The clinician and care team should consider the patient's cultural and religious beliefs and how these might affect decision-making regarding withdrawal of LST. Based on this information, the clinician and care team should recommend withdrawal of LST coupled with a shift to palliative care. This process can be facilitated by holding a multi-disciplinary care conference, which involves the patient (if able), surrogate, loved ones, clinicians, nurses, chaplain, and other care team members. Shared decision-making, consensus regarding withdrawal of LST, and clarifying goals of care should be emphasized. For some cases, ethics consultation can be helpful (10, 11).

Clinicians may wonder whether withdrawing MCS is a form of physician-assisted suicide or euthanasia. However, carrying out an informed request to withdraw an unwanted LST such as MCS differs from physician-assisted suicide and euthanasia in important ways. First, when withdrawing an unwanted LST, the clinician's intent is to remove a treatment the patient or surrogate regards as non-beneficial, burdensome, and inconsistent with the patient's healthcare-related values, goals, and preferences—not to hasten the patient's death. In contrast, in physician-assisted suicide, the clinician's intent is to terminate the patient's life by providing a lethal prescription to be taken by the patient. In euthanasia, the clinician's intent is to terminate the patient's life by administering a lethal agent to the patient. Second, death that follows carrying out a patient's or surrogate's informed request to withdraw an unwanted LST is due to the patient's underlying disease and pathophysiology. In contrast, in physician-assisted suicide and euthanasia, death that follows taking, or being administered, a lethal prescription is due to the lethal prescription—a newly introduced pathology—not the underlying disease (4, 5, 10, 15–17, 20).

The U.S. Supreme Court has differentiated withholding and withdrawing LST from physician-assisted suicide and euthanasia. In Vacco, Chief Justice Rehnquist wrote,

While the U.S. Supreme Court has declared a constitutional right to refuse treatment, it has not declared a constitutional right to physician-assisted suicide or euthanasia. Today, physician-assisted suicide is illegal in most U.S. states and euthanasia is illegal in all states (10, 17).

In summary, carrying out an informed patient's or surrogate's request to withdraw LST is ethically and legally permissible and not a form of physician-assisted suicide or euthanasia (Table 2). While, to the author's knowledge, no U.S. court case has involved a patient receiving MCS, given the results of prior ethical analyses involving MCS (4–6) and court decisions involving other LSTs, the same conclusion can be drawn about carrying out informed requests to withdraw MCS.

Despite the permissibility of carrying out informed requests to withdraw other LSTs, MCS has features that may cause some clinicians to question the permissibility of carrying out requests to withdraw it. For example, some argue MCS once started should not be withdrawn as it is a treatment that is continuous and constitutive (i.e., provides a vital function the patient's body no longer provides). Also, death inevitably follows withdrawal of MCS. However, it is widely accepted that carrying out informed requests to withdraw other continuous and constitutive LSTs (e.g., mechanical ventilation, artificial nutrition and hydration, etc.) is ethically and legally permissible (4–6, 25).

Some clinicians may view MCS as a replacement treatment (i.e., the treatment becomes part of the body and assumes all functions of the diseased organ) and, hence, cannot be withdrawn. However, a genuine replacement treatment is one that is responsive to physiologic changes and independent of external control, maintenance, and energy sources. Examples of replacement treatments include bioprosthetic heart valves and organ transplants. Carrying out a request to remove these treatments would be invasive, harmful, introduce a new pathology (i.e., surgical wound) and, hence, unethical. In contrast, MCS does not have the features of a genuine replacement treatment. Also, withdrawing MCS is noninvasive and painless (4–6, 25).

Some clinicians may object to carrying out requests to withdraw MCS as doing so may acutely precipitate heart failure symptoms (e.g., dyspnea) and death may occur shortly thereafter. However, similar symptoms and death may occur shortly after withdrawal of other LSTs such as intravenous inotropic agents, intra-aortic balloon pump therapy, and mechanical ventilation—treatments that are commonly withdrawn in end of life situations. Hence, the possibility of acute symptoms and death shortly after withdrawal of MCS are not ethically relevant (4–6). Rather, the clinician and care team should inform the patient or surrogate regarding potential symptoms associated with withdrawal of MCS, the likely timing of death, and once withdrawal occurs, manage the dying process expectantly.

As mentioned previously, U.S. courts have not recognized any treatment as being morally unique (10). However, courts have not considered withdrawal of MCS. Nonetheless, MCS does not have features that make it a morally unique treatment.

Three case series describing the features of patients who have undergone withdrawal of MCS have been reported by Mayo Clinic researchers. In a series of 68 patients who received VADs during 2003–2009, 26 had died, of which 14 requested, or surrogates requested, withdrawal of VAD support. All were receiving other LSTs. Eight patients died with multiorgan failure. For 12 patients, requests for withdrawal of VAD support were made by surrogates. For 11 patients, multidisciplinary care conferences were held before withdrawing VAD support. All died within a day of withdrawing of VAD support (4).

In a series of 47 patients who received TAHs during 2007–2015, 21 had died, of which 14 requested, or their surrogates requested, withdrawal of TAH support. All were receiving other LSTs. All died with multiorgan failure. For 13 patients, requests for withdrawal of TAH support were made by surrogates. For all 14 patients, multidisciplinary care conferences were held before withdrawing TAH support. All died within minutes of withdrawing TAH support (5).

In a series of 235 patients who received ECMO during 2010–2014, 118 had died. For 62 patients, requests for withdrawal of ECMO support were made. All were receiving other LSTs. Forty-six patients died with multiorgan failure. None of the patients had decisional capacity. For all patients, decisions to withdrawal ECMO were jointly reached by surrogates and clinicians. All died within a day of withdrawing ECMO support (6).

Other series have had similar results (26, 27).

Notably, in these three series, many patients did not have ADs, and of those who did, their ADs did not mention the MCS technology.

Obviously, intentionally withdrawing MCS from a patient without consent is wrong and a form of killing. Because physician-assisted suicide is illegal in most U.S. states and euthanasia is illegal in all U.S. states, the clinician's intent when withdrawing MCS must be to remove a treatment the patient or surrogate regard as non-beneficial, burdensome, and no longer consistent with the patient's healthcare-related values, goals, and preferences. The intent must not be to terminate the patient's life (17).

Pellegrino describes a 3-question approach to responding to requests to withdraw LST (28). The first question is, “Who decides?” In the U.S., ethically and legally, the patient has the authority to make healthcare-related decisions and this authority supersedes the clinician's authority. If the patient lacks decisional capacity, then the patient's AD and surrogate guide decision-making. The clinician's duty is to ensure that a request to withdraw LST is informed. In the 3 previously described case series, only a few patients had decisional capacity. Hence, for most patients, surrogates made decisions. Of the patients who had ADs, none of the ADs addressed MCS. Hence, surrogates had to rely on “substituted judgement” or “best interests” in making decisions. For nearly all patients, decisions to withdraw MCS were made after multidisciplinary care conferences.

The second question is, “By what criteria?” Answering this question requires assessment of the LST's clinical effectiveness, and its perceived benefits and burdens. The clinician determines treatment effectiveness, whereas the patient determines treatment benefits and burdens. In the 3 previously described series involving MCS, nearly all decisions to withdraw MCS were made during multidisciplinary care conferences. Ongoing MCS was perceived by clinicians and care teams as medically ineffective and by patients and usually surrogates as non-beneficial and burdensome. This scenario, in which MCS merely maintains circulation and a moribund state, has been described as “destination nowhere” (29). In the three previously described series, withdrawal of MCS was justified.

The third question is, “How are conflicts among decision-makers resolved and prevented?” When conflicts arise in the care of patients receiving MCS, care conferences involving the patient, surrogate, and multidisciplinary care teams, as well as palliative care and ethics consultation can be helpful in resolving them. All patients being considered for, or receiving, MCS should undergo advanced care planning, also known as “preparedness planning,” including completion of an AD that addresses the MCS technology and its management at the end of life. Involving palliative medicine specialists in this process can be especially helpful. During these discussions, the circumstances surrounding permissibility of withdrawing MCS should be discussed including what to do if device failure, catastrophic complications, debilitative comorbid conditions (e.g., stroke), and inadequate quality of life occur (10, 11, 30–32). Such planning may prevent conflicts.

Processes for withdrawing specific MCS technologies—VAD, TAH, and ECMO support—are described elsewhere (33–37). Overall, withdrawal of MCS should be based on established palliative care principles and evidence-based best practices. The clinician should anticipate and manage symptoms that occur during the withdrawal process, involve palliative medicine specialists if necessary, and provide comfort to affected love ones.

Some clinicians, despite the ethical and legal permissibility of carrying out informed requests to withdraw LST, may object to the practice. If acceding to such a request violates a clinician's conscience, then the clinician should arrange for a transfer of the patient's care to another accepting clinician. In the meantime, the patient should not be abandoned. Similarly, clinicians and other care team members (e.g., nurses) who conscientiously object to withdrawing MCS should not be compelled to do so (4–6, 10).