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Nervous System: Unit IV > Coma > Flashcards

Flashcards in Coma Deck (17)
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Delirium definition

fluctuating confusion, inattention, misperceptions (illusions or hallucinations).


Stupor definition

a sleep-like state from which the patient can be aroused only by vigorous stimuli.


Coma definition

a sleep-like state where the patient is unresponsive to external stimuli, and there are no sleep-wake cycles.  Usually lasts no more than 4 weeks.  GCS 8 or less. 


Glasgow Coma Scale

  • Motor
    • 1 = no response
    • 2 = extension (decerebrate)
    • 3 = flexion (decort)
    • 4 = normal flexion/withdrawal
    • 5 = localizes pain
    • 6 = obeys command
  • Verbalization
    • 1 = no response
    • 2 = incomprehensible sounds
    • 3 = innapropriate words
    • 4 = confused
    • 5 = oriented 
  • Eye opening
    • 1 = no eye opening
    • 2 = opens to pain
    • 3 = opens to voice
    • 4 = spontaneous eye opening


Types of abnormal postures

  • Decorticate (flexion) – upper extremity flexion with lower extremity extension (suggests lesion at hemispheres)
  • Decerebrate (extension)– upper extremity extension with lower extremity extension (suggests lesion at upper brainstem)
  • Prognosis of decerebrate is worse than decorticate


"Determination of Death"

  • Pt. has sustained irreversible cessation of circulatory and respiratory functions; or
  • Pt. has sustained irreversible cessation of all functions of the entire brain, including the brainstem.


Criteria of brain death

  • unresponsiveness
    • deep coma; GCS = 3
  • absent motor responses during application of painful stimulus
    • spinal reflexes may be present
    • seizures or flex/extend posturing are not
  • brainstem reflexes are absent
    • pupils, corneals, oculocephalic, oculovestibular, cough, gag, respirations
    • apnea test is positive
  • specific vitals
    • core body temp 32.2 C (90 F)
    • no toxic explanation for low neuro state
    • adequate BP & pulse (SBP 90, P>50)


Corneal reflex test

  • Touch cornea with tissue ==> (normal) blink response
  • Tests CNs V and VII
  • @ brain death: no blink response in either ey


Cold Caloric Test

  • "oculovestibular reflex"
  • Test: Flush each external auditory canal with 20 ml ice water x 2 and observe
    • normal response: eyes turn toward theipsilateral ear, with horizontal nystagmus to the contralateral ear.
  • Tests CNs VIII, III, IV and VI
  • @ brain death: no eye movements


Cough reflex test

  • Test: Suction the trachea at the carina.
    • normal response: cough
  • Tests CN X
  • @ brain death: no cough response


Gag reflex test

  • Test: touch the oropharynx with Q-tip ==> (normal) gag
  • Tests CNs IX and X
  • @ brain death: no movement of the oral structures.


Situations in which organ donation occurs

  1. Donation after Brain Death
  2. Donation after Cardiac Death
  • **patient must be declared dead prior to organ harvesting


Characteristics of consciousness

  • product of biological events occurring within brainstem and thalamus
  • derives from the activation of the intralaminar nuclei of the thalamus by the reticular activating system which project from the reticular formation of the brainstem 


Apnea test procedure

  1. Deliver 100% O2 for 10 minutes.
  2. pCO2 is around 40 mmHg on ABG.
  3. Maintain adequate blood pressure (~90) and pulse (>50).  
  4. Determine if pt has tripped the vent recently.
  5. Disconnect vent from ET tube and begin timing
  6. Deliver O2 at 6L/min by t-piece, thus oxygen is being delivered.
  7. Observe and feel for respiratory effort (if breathing is observed, stop test and reconnect ventilator)
  8. After 8 minutes, draw blood gas and reconnect ventillator.  
  • **If no respiratory effort was observed and pCO2 is more than 20 mmHg higher than baseline, the apnea test is positive, consistent with brain death.


Confirmatory tests for brain death

  • Cerebral angiogram → 4 vessel, in brain death no flow above neck.
  • EEG → flat line almost, not entirely flat b/c of artifacts from vent and moving patient
  • Evoked responses → BAER, VER, Somatosensory ER
  • Radionucleotide scan → cerebral blood flow
  • CT angiogram → contrast media and CT immediately. Most conclusive.
  • Transcranial doppler blood flow study → Last choice. Difficult.


Conditions under which physician performs confirmatory tests for brain death

  • If BP/Pulse cannot be stabilized
  • Anatomy doesn’t allow examination
  • Patient is a young child (always if <1 yo)


Considerations in organ donation after brain death

  • Pt must be dead before harvesting
  • The surgeon harvesting may not be involved in determination and death
  • In donation after cardiac death, families should be warned that the patient may not die after withdrawal of life support, will be returned to ICU
  • Proper documentation of cardiac and brain death