Coma and End of Life Flashcards
What is a coma?
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.
Possible outcomes of a coma
Cortical function can return fully if treated in time
Cortical function can minimally return (persistent vegitative state)
Brain death: progressive edema and neuronal death
What are the components of the ascending reticular activating system?
Tegmental pons, midbrain, thalamic intralaminar nuclei/basal forebrain, cerebral cortex (frontal and limbic)
How can a unilateral cerebral lesion cause a coma?
If edema affects the contralateral hemisphere or herniation compresses the ARAS
What brain stem reflexes can be examined in an unresponsive patient?
Motor responses
Breathing patterns
Pupils
Eye movements
What does an asymmetrical abnormality in a comatose patient suggest?
Structural (infarct, hemorrhage, tumor) rather than a toxi-metabolic cause of coma
What is decorticate posturing?
Flexion of upper, extension of lower limbs suggesting a lesion in cerebral hemisphere
What is decerebrate posturing?
Extension of upper and lower limbs suggesting lesion at midbrain (red nucleus)
What are the clinical signs of toximetabolic coma?
Myoclonic jerks
Asterixis
What is Cheyne-Stokes respiration?
Alternating tatchypnea and apnea (crescendo, decrescendo) from bilateral cortical lesions
What is the pupillary light reflex in a metabolic coma?
Pupillary light reflex is preserved, even when other brain stem reflexes are lost
What are the major causes of tiny pupils in an unresponsive patient?
Narcotics, cholinergic eyedrops (glaucoma Rx)
May be normal in awake elderly patients
What does a blown fixed pupil represent?
CN III compression from uncal herniation: EMERGENCY!
How do you test eye movements in an unresponsive patient?
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*
What is brain death?
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.
What are the signs of cerebral function?
Decerebrate or decorticate posturing
Seizures, swallowing, yawning, vocalization
Cranial nerve reflexes
Spontaneous breathing
What is the dual role of medicine at the end of life?
Prolong life where feasible/appropriate
Provide comfort, relieve suffering
What is an advanced directive?
What to do, and what not to do in certain scenarios
What quality of life features to preserve
Arrange finances, wills, funeral plans
What are problems using gastrostomy tubes in demented patients?
May pull out tube, requiring sedation or restraining
Prolong life with decrease in quality of life
Uncertain benefit for preventing aspiration
How are ALS patients supported during late stages of respiratory decline?
Mechanical ventilation via tracheostomy
Supportive with O2, CPAP/BiPAP, home suctioning
If a patient in a persistent vegitative state shows no cognitive improvement, what are the options?
Withhold therapy: no resuscitation, antibiotics or anti-thrombotics
Withdraw therapy: disconnect life sustaining devices, stop medications/dialysis
