Q: I recently cared for a patient who was in a persistent vegetative state (PVS) after the family had made the decision to discontinue all artificial life-sustaining measures. The patient's physician refused to order opioids, stating that this patient was in coma and could not perceive pain. Is there evidence to support this statement?

A: The answer to your question is complex, and in light of recent events is a subject of significant debate. The ability to answer your question accurately requires a clarification of the terms coma and PVS. These terms are often used synonymously, which is incorrect.

Coma is best defined as a state of pathologic unconsciousness where a patient is unarousable and unaware of his or her environment. It is caused by dysfunction of the reticular activating system above the level of the mid-pons, or by bilateral cerebral hemisphere dysfunction.1

Patients in a PVS are a subgroup of comatose patients who have suffered anoxic brain injury and progress to a state of wakefulness without awareness. This term was first used in 19722,3 and is defined as

* no evidence of awareness of self or environment and an inability to interact with others;

* no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli;

* no evidence of language comprehension or expression;

* intermittent wakefulness manifested by the presence of sleep-wake cycles;

* sufficiently preserved hypothalamic and brain stem autonomic function to permit survival with nursing and medical care;

* bowel and bladder incontinence; and

* variably preserved cranial nerve reflexes and spinal reflexes.1,4,5

If a patient remains comatose, the usual outcomes are recovery, PVS, or death within 2 weeks. Nontraumatic vegetative state is considered permanent after 3 months, and chances of any recovery are essentially nonexistent.4

In neurology, the terms awareness and consciousness are synonymous. They are used to describe a patient's ability to perceive, interact, and communicate with the environment.6 The perception of consciousness is primarily the result of coordinated activity of several cortical areas. The essential features of PVS are the loss of any meaningful cognitive responsiveness, a lack of awareness/consciousness, and the preservation of spontaneous breathing and some other reflex responses. A key clinical component is that these patients are unable to interact with others in any meaningful way. Additionally, there is no evidence of language comprehension or expression. While patients in a PVS do show arousal responses to noxious stimuli, such as eye opening, changes in breathing patterns, and occasional grimacing, clinical experience and neuropathological examination suggest that they are unaware of pain.1,4-6

In most patients in a PVS, the nociceptive pathways in the brain stem and spinal cord are usually intact, which allows them to react to painful stimuli with a variety of behavioral responses.6 These behavioral responses only demonstrate that the patient's nociceptive pathways are intact, and should not be considered evidence of pain perception. The actual conscious experience of pain is mediated by various activities of the cortical areas, which make it highly unlikely that the patient in a PVS is capable of experiencing or perceiving pain. Unfortunately, as of now there are no functional imaging data on pain processing that might further substantiate this claim.6

The use of opioids in this patient population is, therefore, most often based on individual provider judgment. Published recommendations for use of analgesics in this population are highly variable. At least one suggests that if patients experience vegetative responses, such as tachycardia or sweating, in response to painful stimulus, the use of analgesics may be appropriate.6

Patients in a PVS present unique challenges to hospice and palliative care nurses. Caring family members and friends often perceive reflexive movements as purposeful, which can cause them to question their decision to pursue palliative care. The lack of large randomized controlled clinical trials on pain in patients in a PVS makes it difficult to know when and whether analgesics are of benefit in this patient population. Families may perceive not giving analgesics as inhumane, while others may perceive it as euthanasia. There is no easy answer to this dilemma. In my institution if the family perceives the patient to be in pain, or there is significant reflexive response to painful stimulus, we err on the side of analgesia.

Darrell A. Owens, PhD, APRN, CNS

Darrell A. Owens, PhD, APRN, CNS, is a Palliative Care Specialist at the University of Washington at Harborview Medical Center, Seattle, and a member of the Editorial Advisory Board, Journal of Hospice and Palliative Nursing.

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