Coma and End of Life

Question 1

What is a coma?

Answer 1

Sleep-like unarousable and unresponsive state. Cannot wake up, even with painful stimulus.
The cerebral cortex is not functioning (extensive bilateral dysfunction), but brainstem reflexes are intact.

Question 2

Possible outcomes of a coma

Answer 2

Cortical function can return fully if treated in time
Cortical function can minimally return (persistent vegitative state)
Brain death: progressive edema and neuronal death

Question 3

What are the components of the ascending reticular activating system?

Answer 3

Tegmental pons, midbrain, thalamic intralaminar nuclei/basal forebrain, cerebral cortex (frontal and limbic)

Question 4

How can a unilateral cerebral lesion cause a coma?

Answer 4

If edema affects the contralateral hemisphere or herniation compresses the ARAS

Question 5

What brain stem reflexes can be examined in an unresponsive patient?

Answer 5

Motor responses
Breathing patterns
Pupils
Eye movements

Question 6

What does an asymmetrical abnormality in a comatose patient suggest?

Answer 6

Structural (infarct, hemorrhage, tumor) rather than a toxi-metabolic cause of coma

Question 7

What is decorticate posturing?

Answer 7

Flexion of upper, extension of lower limbs suggesting a lesion in cerebral hemisphere

Question 8

What is decerebrate posturing?

Answer 8

Extension of upper and lower limbs suggesting lesion at midbrain (red nucleus)

Question 9

What are the clinical signs of toximetabolic coma?

Answer 9

Myoclonic jerks

Asterixis

Question 10

What is Cheyne-Stokes respiration?

Answer 10

Alternating tatchypnea and apnea (crescendo, decrescendo) from bilateral cortical lesions

Question 11

What is the pupillary light reflex in a metabolic coma?

Answer 11

Pupillary light reflex is preserved, even when other brain stem reflexes are lost

Question 12

What are the major causes of tiny pupils in an unresponsive patient?

Answer 12

Narcotics, cholinergic eyedrops (glaucoma Rx)

May be normal in awake elderly patients

Question 13

What does a blown fixed pupil represent?

Answer 13

CN III compression from uncal herniation: EMERGENCY!

Question 14

How do you test eye movements in an unresponsive patient?

Answer 14

1) Dolls eye reflex: Oculocephalic reflex = Eyes conjugately move in direction opposite passive rotation of the head
2) Oculovestibular reflex: cold water in ear canal causes eyes to conjugately move toward the cold
* Abnormal reflex indicates brainstem depression*

Question 15

What is brain death?

Answer 15

Irreversible loss of function for cerebrum and brainstem. Failure of other organs will follow.
Shows no improvement after treating reversible causes, or watchful observation >6hrs.

Question 16

What are the signs of cerebral function?

Answer 16

Decerebrate or decorticate posturing
Seizures, swallowing, yawning, vocalization
Cranial nerve reflexes
Spontaneous breathing

Question 17

What is the dual role of medicine at the end of life?

Answer 17

Prolong life where feasible/appropriate

Provide comfort, relieve suffering

Question 18

What is an advanced directive?

Answer 18

What to do, and what not to do in certain scenarios
What quality of life features to preserve
Arrange finances, wills, funeral plans

Question 19

What are problems using gastrostomy tubes in demented patients?

Answer 19

May pull out tube, requiring sedation or restraining
Prolong life with decrease in quality of life
Uncertain benefit for preventing aspiration

Question 20

How are ALS patients supported during late stages of respiratory decline?

Answer 20

Mechanical ventilation via tracheostomy

Supportive with O2, CPAP/BiPAP, home suctioning

Question 21

If a patient in a persistent vegitative state shows no cognitive improvement, what are the options?

Answer 21

Withhold therapy: no resuscitation, antibiotics or anti-thrombotics
Withdraw therapy: disconnect life sustaining devices, stop medications/dialysis