A coma is a prolonged state of unconsciousness. Individuals in a coma cannot be awakened and fail to respond normally to pain or light. Coma patients exhibit no signs of conscious awareness or behavioral interactions with their surroundings. While coma patients are unresponsive and lack awareness, they are different from brain dead individuals in that they still have brain stem function and do not meet the criteria for death. However, determining whether coma patients should be considered living or dead remains an ongoing ethical debate.
What is a coma?
A coma is a state of prolonged unconsciousness that lasts more than 6 hours in which a person cannot be awakened and fails to respond normally to painful stimuli, light, or sound. It is usually caused by damage to the brain stem, which controls arousal and awareness.
Some key features of a coma include:
– Lack of awareness and wakefulness
– No meaningful response to external stimuli
– Inability to communicate
– Lack of voluntary movements
– Minimal reflex responses
– Irregular breathing patterns
Causes of coma include traumatic brain injury, stroke, lack of oxygen to the brain (anoxia), metabolic abnormalities, infections, brain tumors, and intoxication. The underlying cause determines the chances of recovery. While some patients emerge from coma within days or weeks, others remain in a vegetative state for years. Rarely, some people eventually regain awareness after being in a coma for a long period of time.
Brain death vs coma
Brain death is the complete and irreversible loss of all brain function, including the brain stem. It is legally equivalent to death in most countries. In contrast, coma patients still retain some brain stem function. Key differences between brain death and coma include:
| Brain Death | Coma |
|---|---|
| No brain activity detectable on EEG | EEG shows some brain activity, albeit abnormal |
| No pupillary, corneal, vestibulo-ocular, or gag reflexes | Usually retains some primitive reflexes |
| No respiratory drive when taken off ventilator | Continues to breathe independently, albeit abnormally, when off ventilator |
| No sleep/wake cycles | Retains some sleep/wake rhythm |
| No response to stimuli | May have minimal response to intense stimuli |
| Irreversible if criteria persist | Some recovery possible depending on cause |
While both coma patients and brain dead individuals lack consciousness, coma patients still have some brain activity and the potential for recovery. Brain dead patients meet the legal criteria for death and have no chance of recovery.
Procedures to diagnose brain death
Because brain death is equivalent to legal death, diagnosis must follow strict guidelines. Procedures to definitively declare brain death include:
– Documenting the underlying cause and irreversibility of coma
– Repeated examinations by two physicians at least 6 hours apart
– Lack of pupillary response to bright light
– No corneal reflexes when cornea is touched
– No oculocephalic reflex or vestibulo-ocular reflex
– No motor response to painful stimulus applied to the face, limbs or trunk
– No gag, cough, or sucking reflex
– No respiratory efforts when taken off ventilator for apnea testing
– Flat or isoelectric EEG
– No blood flow on brain radionuclide scan
Brain death can only be declared when all tests conclusively confirm irreversible cessation of all brain activity. This rigorous process ensures no one is mistakenly declared dead while any possibility of recovery remains.
Are coma patients living or dead?
While brain death is a definitive declaration of death, coma patients remain alive yet unresponsive. Key reasons why coma patients are considered living include:
– Coma patients retain brain stem function responsible for spontaneous breathing and heartbeat. If breathing stops, they can often be kept alive by medical ventilation.
– They maintain some sleep/wake cycles and circadian rhythms.
– They show subtle responses to some external stimuli like loud noises or pain.
– Their EEGs show low level metabolic brain activity.
– Some coma patients progress to a vegetative state where they may open their eyes, make sounds, and demonstrate reflexes.
– In rare cases, a small percentage of coma patients regain full consciousness days, weeks, or even years later.
Since coma patients retain brain stem function and occasionally recover, they do not meet criteria for death and are considered alive. However, their prognosis depends on the extent of brain damage.
Prognosis for coma patients
The prognosis for coma patients varies greatly depending on the cause and severity of damage:
– **Metabolic comas:** These are often reversible once the underlying cause is treated. Overdose and diabetic comas have better prognosis.
– **Anoxic brain injury:** Lack of oxygen to the brain carries worse prognosis. Many remain in vegetative state. Recovery of awareness is unlikely after 4 weeks in coma.
– **Traumatic brain injury:** Younger patients have better chance of regaining consciousness. However, significant disability is common.
– **Non-traumatic comas:** Usually due to stroke, hemorrhage, or brain tumors. Mortality rates approach 80% by 1 year. Significant neurological impairment is typical among survivors.
While coma patients are considered living, most have poor prognosis and limited potential for meaningful recovery. However, some emerging treatments provide hope.
Emerging treatments for prolonged coma
While prognosis is generally poor, some new treatments aim to improve neurological outcomes in prolonged coma:
– **Stem cell therapy** – Stem cells injected into the brain or spinal fluid aim to regenerate damaged neurons and neural connections. Small studies show improved consciousness in some cases.
– **Deep brain stimulation** – Electrodes implanted in the thalamus provide electrical stimulation to external cortex to restore responsiveness. More research is needed.
– **Drug therapy** – Zolpidem and Amantadine aim to increase dopamine and stimulate neural activity to enhance awareness. Effectiveness remains unproven.
– **Sensory stimulation** – Auditory, visual, or sensory stimulation during coma aims to stimulate neural pathways. Evidence is limited but positive.
– **Neuroplasticity training** – Computerized training aims to rewire intact brain circuits through repeated stimulation and feedback. Benefits are theoretical but promising.
While these treatments have potential to improve outcomes, larger studies are needed to demonstrate meaningful benefits. But they provide hope that some coma patients may regain awareness with advanced interventions.
Ethical questions around sustaining coma patients
Keeping coma patients alive with medical support for prolonged periods raises important ethical concerns:
– **Quality of life** – Maintaining coma patients with minimal awareness raises questions about dignity and quality of life. Is it appropriate to sustain life with little consciousness?
– **Pain and suffering** – While coma patients lack awareness, some degree of pain perception may remain. Prolonging minimal awareness may extend suffering.
– **Autonomy** – Without a clear advanced directive, families must make difficult choices about continuing life support against the wishes of the patient.
– **Resource allocation** – Keeping coma patients alive long-term consumes significant medical resources and caregiver time. Is this misallocation of scarce health resources?
– **False hope** – Families may insist on futile care based on unrealistic hopes of recovery despite poor prognosis. More harm may result from sustaining coma with poor outcomes.
While consensus is lacking, most ethicists agree that prolonged comas with poor prognosis and limited consciousness raise difficult questions about the ethics of continuing life-sustaining therapies.
Legal and ethical criteria for sustaining life support
Most medical experts and ethicists agree on the following guidelines about continuing or withdrawing life support for coma patients:
– Life support should be continued in early coma while diagnostic evaluation occurs and prognosis is determined.
– If the coma is irreversible and exhibits no awareness, life support may be discontinued after shared decision making with family.
– If there is partial awareness or recovery of consciousness, life support should be continued.
– In prolonged coma with no realistic hope of meaningful recovery, life support may be ethically withdrawn.
– Any prior expressed wishes of patient regarding life support should be honored.
– Without an advanced directive, family and doctors should make decision based on the patient’s values, quality of life, and previously indicated preferences.
– Ethics committees can help guide decisions when families and medical teams disagree.
While sustain life is the default, withdrawal of support may be ethically appropriate in prolonged coma with no potential for conscious recovery based on the patient’s preferences and values. Ongoing consent, sound prognosis, shared decision making, and ethics consultations can help guide these difficult decisions.
Conclusion
In contrast to brain death, coma patients retain brain stem function and do not meet criteria for death – so they are considered legally alive. However, most coma patients face poor neurological outcomes, especially if lacking awareness for weeks after the initial injury. While emerging therapies may improve prognosis, long-term coma with minimal consciousness raises difficult ethical issues around sustaining life indefinitely. With shared decision making guided by the patient’s values, life support may be ethically withdrawn in some cases of irreversible coma with no hope of meaningful recovery. Ultimately, each case requires careful weighing of prognosis, quality of life, patient autonomy, and ethical principles.