Bioethics
A person in a coma is said to be in an  unconscious state. Perspectives on personhood, identity and consciousness come into play when discussing the metaphysical and bioethical views on comas. It has been argued that unawareness should be just as ethically relevant and important as a state of awareness and that there should be metaphysical support of unawareness as a state.In the ethical discussions about disorders of consciousness (DOCs), two abilities are usually considered as central: experiencing well-being and having interest. Well-being can broadly be understood as the positive effect related to what makes life good (according to specific standards) for the individual in question. The only condition for well-being broadly considered is the ability to experience its ‘positiveness’. That said, because experiencing positiveness is a basic emotional process with phylogenetic roots, it is likely to occur at a completely unaware level and therefore, introduces the idea of an unconscious well-being. As such, the ability of having interests, is crucial for describing two abilities which those with comas are deficient in. Having an interest in a certain domain can be understood as having a stake in something that can affect what makes our life good in that domain. An interest is what directly and immediately improves life from a certain point of view or within a particular domain, or greatly increases the likelihood of life improvement enabling the subject to realize some good. That said, sensitivity to reward signals is a fundamental element in the learning process, both consciously and unconsciously.
Decerebrate posturing is a stereotypical posturing in which the legs are similarly extended (stretched), but the arms are also stretched (extended at the elbow). The posturing is critical since it indicates where the damage is in the central nervous system. A decorticate posturing indicates a lesion (a point of damage) at or above the red nucleus, whereas a decerebrate posturing indicates a lesion at or below the red nucleus. In other words, a decorticate lesion is closer to the cortex, as opposed to a decerebrate posturing which indicates that the lesion is closer to the brainstem. Pupil size
Pupil assessment is often a critical portion of a comatose examination, as it can give information as to the cause of the coma; the following table is a technical, medical guideline for common pupil findings and their possible interpretations:

Severity
A coma can be classified as (1) supratentorial (above Tentorium cerebelli), (2) infratentorial (below Tentorium cerebelli), (3) metabolic or (4) diffused. This classification is merely dependent on the position of the original damage that caused the coma, and does not correlate with severity or the prognosis. The severity of coma impairment however is categorized into several levels. Patients may or may not progress through these levels. In the first level, the brain responsiveness lessens, normal reflexes are lost, the patient no longer responds to pain and cannot hear.