The End of Life: Medical Considerations - Persistent Vegetative State
pvs percent patients consciousness
Severe damage to the brain can cause a vegetative state. This state is characterized by a complete lack of awareness of self and the environment, but the patient retains waking and sleeping cycles. Patients have been known to recover from vegetative states after a few days or weeks; however, when loss of cognition lasts more than a few weeks, the patient is said to be in a persistent vegetative state (PVS).
Table 4.4 compares the characteristics of PVS with other disorders of consciousness. The patient is not conscious in either a vegetative state or a coma, while the patient in the minimally conscious state (MCS) has, as the name suggests, partial consciousness. Partial consciousness means that the consciousness is severely altered, but the patient shows an awareness of self or the environment, exhibiting behaviors such as following simple commands and smiling or crying at appropriate times. In contrast, the patient with locked-in syndrome has full consciousness, but all the voluntary muscles of the body are paralyzed except (usually) for those that control vertical eye movement and blinking.
The American Medical Association (AMA), in light of the continuing debate over life-sustaining treatments and permanently unconscious patients, has discussed the persistent vegetative state and outlined the criteria for diagnosis of this condition. In "Persistent Vegetative State and the Decision to Withdraw or Withhold Life Support" (Journal of the American Medical Association, vol. 263, no. 3, January 19, 1990), the most recent estimates available on the topic, the Council on Scientific Affairs and the Council on Ethical and Judicial Affairs of the AMA estimated that there were 15,000 to 25,000 PVS patients in the United States.
The AMA clinical criteria for PVS are:
Chronic unconscious wakefulness without awareness, though wakefulness may be accompanied by opening of eyes, unintelligible sounds, movements of facial muscles, and even smiles.
Lack of intelligible speech and failure to comprehend others' words.
Inability to make purposeful or voluntary movements—movements made are reflex responses to external or unpleasant stimuli.
Lack of sustained visual and auditory responses to external stimuli. Some PVS patients may turn their heads or move their eyes toward sounds or moving objects, but these movements are brief reflex reactions that do not require upper-brain functioning.
Lack of bowel and bladder control.
Presence of non-neurological functions, such as the ability to swallow and digest food.
Ability to breathe independently.
Chances of Recovery
Representatives from five neurological societies, along with medical, ethical, and legal consultants, joined forces to investigate the medical facts about PVS, and published the results of their study in 1994. This report has its critics; nonetheless, it is considered to be medically authoritative and is a basic reference point on the topic for medical practitioners in the United States (Thomas A. Mappes, Kennedy Institute of Ethics Journal, vol. 13, no. 2, 2003). In "Persistent Vegetative State, Prospective Thinking, and Advance Directives," the Multi-Society Task Force concluded that the clinical course and outcome of a persistent vegetative state depend on the initial cause of the condition. In "Medical Aspects of the Persistent Vegetative State" (New England Journal of Medicine, vol. 330, nos. 21 and 22, May 26 and June 2, 1994), the task force reported the recovery rates from disorders that may cause PVS.
TRAUMATIC BRAIN INJURIES.
The task force investigated a total of 434 adult PVS patients one month after their traumatic brain injuries. Three months after the injury, 33 percent had recovered consciousness, while 67 percent had either died or remained in a PVS. At six months, 46 percent of the original 434 patients had recovered consciousness, compared with 52 percent at one year.
Recovery from PVS has another dimension: function recovery. After one year, 33 percent of the 434 patients had died, 15 percent remained in a PVS, 28 percent were severely disabled, and 17 percent were moderately disabled. Only 7 percent were diagnosed as having a good recovery, which meant they were able to resume normal social and job-related activities. The task force also found that PVS patients younger than 40 years of age had a better chance of improvement than those older than 40.
Children who experienced traumatic injuries causing a PVS also showed a better recovery rate than adults. Of the 106 PVS children surveyed, 24 percent recovered consciousness within three months. At one year, 62 percent had recovered, 9 percent had died, and 29 percent remained in a PVS.
The prognosis of functional recovery among children, like that among adults, was better when consciousness was regained within six months. After one year, 35 percent of the children suffered severe disability, 16 percent had moderate disability, and 11 percent had a good recovery. The researchers found that while children had a good recovery after six months and exhibited moderate disability after one year, adults who recovered after six months suffered serious disabilities.
NONTRAUMATIC BRAIN INJURIES.
Nontraumatic brain injuries, which refer to oxygen deprivation caused by things such as stroke, are far more likely to result in death or PVS and much less likely to result in recovery of consciousness. Of the 169 adult PVS patients who experienced nontraumatic injuries, after three months about 89 percent stayed in a PVS or died, while only 11 percent had regained consciousness. After a year, 53 percent had died, 32 percent remained in a PVS, and 15 percent had recovered consciousness. The 15 percent who regained consciousness showed little recovery of function, with only one patient having a good recovery.
Of 45 PVS children who had nontraumatic brain injuries, only 13 percent regained consciousness at one year. Twenty-two percent died, and 65 percent remained in PVS. As with traumatic head injuries, children fared better in recovery of function than adults, though only 6 percent had good recovery of function.
DEGENERATIVE AND METABOLIC BRAIN DISORDERS.
The Multi-Society Task Force on PVS reported that people who enter PVS resulting from degenerative and metabolic diseases do not regain consciousness. Degenerative brain disorders, such as Alzheimer's disease, produce irreversible unconsciousness at their terminal stages. Within a few weeks or months, the patient usually succumbs to the disease. Metabolic disorders, such as toxic kidney disease, are severe conditions that also result in irreversible coma.
SEVERE CONGENITAL MALFORMATIONS OF THE NERVOUS SYSTEM.
Infants and children in a PVS due to severe brain malformations are unlikely to regain consciousness. Most who do recover consciousness exhibit serious disabilities. Anencephalic babies, missing a major part of the brain, skull, and scalp, have no capacity for consciousness.
LATE RECOVERY OF CONSCIOUSNESS.
Only a handful of PVS patients have been known to regain consciousness after 12 months. All have been left with severe disabilities.
TABLE 4.5 Number of doctors (and percent) responding that it is appropriate to consider treatment-limiting decisions at particular intervals after brain damage, 1998
No treating acute infections with antibiotics
No treating other life-threatening conditions
Withdrawing artificial nutrition and hydration
Over 1 year
SOURCE: K. Dierickx, et al., "Table 4. Interval after Brain Damage When It Is Appropriate to Consider Treatment-Limiting Decisions," in "Belgian Doctors' Attitudes on the Management of Patients in Persistent Vegetative State (PVS): Ethical and Regulatory Aspects," Acta Neurochirurgica, vol. 140, no. 5, May, 1998
The Possibility of Locked-In Syndrome
Locked-in syndrome is a rare neurological disorder that has added to the controversy involving PVS patients and the withdrawal of life-sustaining treatments. Locked-in syndrome is characterized by the complete paralysis of all voluntary muscles except those controlling the eyes (see Table 4.4). According to the National Institute of Neurological Disorders and Stroke, people with locked-in syndrome are conscious and have cognitive function. Paralysis, not coma, causes the patients' inability to respond. Patients with this syndrome have been known to communicate by blinking.
Those who oppose the withdrawal of life support from unconscious patients argue that a patient diagnosed to be in a PVS may actually be suffering from locked-in syndrome. However, a thorough neurological examination or an imaging technique known as positron emission tomography (PET) can distinguish between PVS and locked-in patients.
Treatment of PVS Patients
The President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research published the report Deciding to Forego Life-Sustaining Treatment (Washington, DC: U.S. Government Printing Office, 1983) as an offshoot of their study on the definition of death and other health care issues. These landmark reports continue to set the standards for many medical and bioethical decisions. The commission noted that medical treatment of PVS patients is based primarily on maintaining their wellbeing—"preserving life, relieving pain and suffering, protecting against disability, and returning maximally effective functioning."
However, if a patient is diagnosed as irreversibly unconscious, then continued treatment does not really benefit the patient. The only reason for continued treatment is the possibility that the prognosis of PVS might be incorrect. The commission observed that the few patients who did regain consciousness suffered severe disabilities. It concluded that most patients would not want to recover and find themselves in a severely disabled condition. The commission added that continuing treatment with the belief that the patient would have refused such a treatment would even be more harmful.
Finally, continued long-term care creates financial and emotional burdens for the patient's family. The commission concluded that most patients value their family's well-being and that it would not serve a patient's interests to let prolonged care exact such heavy tolls on the family.
Table 4.5 shows the interval after brain damage when a sample of 208 specialist physicians in Belgium involved in the care of patients in PVS think it is appropriate to consider treatment-limiting decisions for their PVS patients. The numbers not in parentheses indicate the number of physicians in the sample answering in that manner, and the numbers in parentheses indicate the percentage of the total sample answering in that manner. Thus, 35 percent of physicians in the sample think that it is appropriate to consider not treating acute infections with antibiotics when a patient has been in PVS for 4 to 6 months. An additional 30 percent thought this to be the case between 7 and 12 months. By the time a person has been in a PVS for 12 months, 76 percent of the physicians in the sample thought that neither acute infections nor other life-threatening conditions should be treated. Sixty-three percent favored withdrawing artificial nutrition and hydration by that time.
Society in general puts a high value on human life, and the continued care of permanently unconscious patients both reflects and reinforces that value. Further, society does not appear to want to see PVS patients abandoned, since such an attitude might carry over to less seriously ill patients.
The patient's family also has a vested interest in continued care, hoping that continued treatment might bring
back their loved one. Many find comfort and meaning in taking care of the patient.
Health care personnel, trained to save lives, often feel that discontinuing treatment is at odds with their professional training. The traditional training of aggressive intervention can be hard to set aside in order to honor a patient's or family's request to forego life support. Health care professionals also lack training in moving from taking care of a dying patient to withdrawing his or her life support. Howard Brody, et al., in "Withdrawing Intensive Life-Sustaining Treatment—Recommendations for Compassionate Clinical Management" (New England Journal of Medicine, vol. 336, no. 9, February 27, 1997), observed that "caring for dying patients and their families exacts a serious toll on physicians and nurses."
While withholding treatment of acute infections or other life-threatening conditions in PVS patients is difficult for family and health care personnel, withdrawing artificial feeding may be even more difficult. Table 4.6 shows what a sample of 208 Belgian physicians who care for PVS patients think should be the extent to which the known views of the patient, family, and caregivers should influence a decision to withdraw artificial feeding. In this sample, 41 percent of the physicians thought that an advance directive of the patient should be the decisive factor, while 43 percent thought that it should be a contributing factor. Few in the sample thought that the family's wishes should be the decisive factor in the decision, but a large proportion thought that the family's wishes should be a contributing factor, along with the views of the caregivers, including the physician him-or herself.
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