Plum and posner’s diagnosis of stupor and coma fourth Edition series editor sid Gilman, md, frcp
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Box 2–1 Coma Scales A number of different scales have been devised for scoring patients with coma. The value of these is in providing a simple estimate of the prognosis for different groups of patients. Obviously, this is related as much to the cause of the coma (when known) as to the current status of the examination. Teasdale and Jennett’s Glasgow Coma Scale (GCS), 2 devised to categorize patients with head trauma, is reproduced below. Unfortunately, when used by emergency room physicians, in- terrater agreement is only moderate. 3 Two simple scales, ACDU (alert, confused, drowsy, unresponsive) and AVPU (alert, response to voice, response to pain, un- responsive) 4 are about as accurate as the GCS and much easier to use. 4 The
ACDU scale appears better at identifying early deterioration in level of con- sciousness. A recently validated coma scale, the FOUR scale (full outline of un- responsiveness), provides more neurologic detail than the GCS. However, no scale is adequate for all patients; hence, the best policy in recording the results of the coma examination is simply to describe the findings. Nevertheless, the GCS is widely used, and still is probably the best for most trauma patients. 5 It is useful to obtain GCS scores, which can be compared against large databases to evaluate prognosis for specific etiologies of coma (see Chapter 9). FOUR Score (Full Outline of Unresponsiveness) 109
Eye Response 4 ¼ eyelids open or opened, tracking, or blinking to command 3 ¼ eyelids open but not tracking 2 ¼ eyelids closed but open to loud voice 1 ¼ eyelids closed but open to pain 0 ¼ eyelids remain closed with pain Motor Response 4 ¼ thumbs-up, fist, or peace sign 3 ¼ localizing to pain 2 ¼ flexion response to pain 1 ¼ extension response to pain 0 ¼ no response to pain or generalized myoclonus status Brainstem Reflexes 4 ¼ pupil and corneal reflexes present 3 ¼ one pupil wide and fixed 2 ¼ pupil or corneal reflexes absent 1 ¼ pupil and corneal reflexes absent 0 ¼ absent pupil, corneal, and cough reflex Respiration 4 ¼ not intubated, regular breathing pattern 3 ¼ not intubated, Cheyne-Stokes breathing pattern 2 ¼ not intubated, irregular breathing 1 ¼ breathes above ventilator rate 0 ¼ breathes at ventilator rate or apnea (continued) 41
make only nonspecific motor responses (winc- ing, restlessness, withdrawal reflexes) without a directed attempt to defend against the stim- ulus are considered to have a nonlocalizing re- sponse and are comatose. Patients who fail to respond at all are in the deepest stage of coma. This rough grading system, from verbal re- sponsiveness, to localizing responses, to non- localizing responses, to no response, is all that is needed for an initial assessment of the depth of unresponsiveness that can be used to follow the progress of the patient. If the initial eval- uation of the level of consciousness demon- strates impairment, it is essential to progress through the next steps of the coma examina- tion as rapidly as possible to safeguard that patient’s life. More elaborate coma scales are described in Box 2–1, but many of these de- pend upon the results of later stages in the examination, and it is never justified to de- lay attending to the basics of airway, breathing, and circulation while performing a more elab- orate scoring evaluation. ABC: AIRWAY, BREATHING, CIRCULATION It is critical to ensure that the patient’s airway is maintained, that he or she is breathing ad- Glasgow Coma Scale Eye Response 4 ¼ eyes open spontaneously 3 ¼ eye opening to verbal command 2 ¼ eye opening to pain 1 ¼ no eye opening Motor Response 6 ¼ obeys commands 5 ¼ localizing pain 4 ¼ withdrawal from pain 3 ¼ flexion response to pain 2 ¼ extension response to pain 1 ¼ no motor response Verbal Response 5 ¼ oriented 4 ¼ confused 3 ¼ inappropriate words 2 ¼ incomprehensible sounds 1 ¼ no verbal response A GCS score of 13 or higher indicates mild brain injury, 9 to 12 moderate brain injury, and 8 or less severe brain injury. AVPU ACDU
Is the patient Is the patient Alert and oriented? Alert and oriented? Responding to voice? Confused? Responding to pain? Drowsy?
Unresponsive? Unresponsive? Box 2–1 Coma Scales (cont.) 42 Plum and Posner’s Diagnosis of Stupor and Coma equately, and that there is sufficient arterial perfusion pressure. The first goal must be to correct any of these conditions if they are found inadequate (Chapter 7). In addition, blood pres- sure, heart rate, and respiration may provide valuable clues to the cause of coma. Circulation It is critical first to ensure that the brain is receiving adequate blood flow. Cerebral per- fusion pressure is the systemic blood pressure minus the intracranial pressure. The physician can measure blood pressure but in the ini- tial examination can only estimate intracranial pressure. Over a wide range of blood pres- sures, cerebral perfusion remains stable be- cause the brain autoregulates its blood flow by mechanisms described in the paragraphs be- low and illustrated in Figure 2–2. If the blood pressure falls too low or becomes too high, autoregulation fails and cerebral perfusion fol- lows perfusion pressure passively; that is, it falls as the blood pressure falls and rises as the blood pressure rises. In this situation, both too low (ischemia) and too high (hypertensive en- cephalopathy; see Chapter 5) a blood pres- sure can damage the brain. To ensure adequate brain perfusion, the physician should attempt to maintain the blood pressure at a level nor- mal for the individual patient. For example, a patient with chronic hypertension autoregu- lates at a higher level than a normotensive pa- tient. Lowering the blood pressure to a ‘‘normal level’’ may deprive the brain of an adequate blood supply (see Figure 2–2). Conversely, the cerebral blood flow (CBF) in children and pregnant women, who normally run low blood pressures, is regulated at lower levels and may develop excessive perfusion if the blood pres- sure is raised (e.g., pre-eclampsia). The perfusion pressure of the brain may be influenced by the position of the head. In a normal individual, as the head is raised, the systemic arterial pressure is maintained by blood pressure reflexes. At the same time, the arterial perfusion pressure to the head is re- duced by the distance the head is raised above the heart, but the intracranial pressure is also reduced because of the improved venous and cerebrospinal fluid (CSF) drainage. The net effect is that there is very little change in brain perfusion pressure or CBF. On the other hand, in a patient with stenosis of a carotid or ver- tebral artery, the perfusion pressure for that vessel may be much lower than systemic arte- rial pressure. If the head of the bed is raised, Figure 2–2. Cerebral autoregulation in hypertension. Schematic representation of autoregulation of cerebral blood flow (CBF) in normotensive (solid line) and hypertensive (dashed line) subjects. In both groups, within a range of about 100 mm Hg, increases or decreases in mean arterial pressure are associated with maintenance of CBF due to appropriate changes in arteriolar resistance. Changes in pressure outside this range are eventually associated with loss of autoregu- lation, leading to a reduction (with hypotension) or an elevation (with marked hypertension) in CBF. Note that hyper- tensive encephalopathy (increased blood flow with pressures exceeding the autoregulatory range) may occur with a mean arterial pressure below 200 mm Hg in the normotensive individual, but may require a much higher mean arterial pressure in patients who have sustained hypertension. Conversely, lowering blood pressure to the ‘‘normal range’’ of a mean arterial pressure of 80 mm Hg (equivalent to 120/60) may produce a clinically significant fall in CBF, particularly if there is a pre- existing cerebrovascular stenosis. Examination of the Comatose Patient 43
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