Disorders of Consciousness Flashcards
what is consciousness?
a state of awareness to environment and self with a responsiveness to stimuli
How is consciousness achieved and maintained?
Via action of the neurons that make up the Ascending Reticular Activating System (ARAS) in brainstem and cerebral cortex
what is the reticular system?
a set of interconnected neurons in the brain stem consisting of 2 neurologic pathways
- Ascending reticular activating system (ARAS)
- Descending reticulospinal tracts
which part of the reticular system originates in the upper pons and midbrain, projecting to the thalamus and hypothalamus and extending to the cerebral cortex, controlling levels of alertness
Ascending reticular activating system - ARAS
which part of the reticular system
travels downward into the spinal cord and modulates spinal reflex activity
Doesn’t affect consciousness
Damage leads to loss or diminished reflexes
Descending reticulospinal tracts
the outer layer of the cerebral hemispheres consisting of grey matter and controls the content of consciousness
Cerebral cortex
self-awareness, language, reasoning, spatial relationship, integration and emotions
what is the difference between conscious and unconscious?
-
Conscious
- Awake, aware, alert and responsive to stimuli or in a normal state of sleep but responsive to stimuli
- Fast neuronal activity can be found all over the brain and signals can be passed between areas of the ARAS -
Unconscious
- unaware and unresponsive to stimuli resulting from damage to the ARAS and/or the cerebrum
- A diminished transmission of signals from the ARAS to the cerebrum
evaluation of an unconscious pt
- Primary Survey (C-A-B)
- Circulation
- Airway
- Breathing - Vital Signs and Secondary Survey
- brief history
- events surrounding loss of consciousness - initial PE
- General - evidence of trauma
- Neurologic Evaluation - CN deficits, Glasgow Coma Score
circulation in a primary survey of an unconscious pt involves?
check pulse
- No Pulse - start CPR
- Pulse present = maintain circulation
- Is BP normal?
— Yes = No further intervention
— No = Treat appropriately (see later slide)
- Is rhythm regular?
— Obtain EKG to confirm
Airway/Breathing in a primary survey of an unconscious pt involves?
- Spontaneous regular respirations = monitor
- No spontaneous respiration or ineffective respirations = provide assisted ventilation
- Mouth-to-mouth/mask (in the field)
- Bag-mask with supplemental oxygen
- May require intubation / ventilator support
how to conduct Vital Signs and Secondary Survey of an unconscious pt?
- BP/pulse (circulation)
- Tx severe HTN (MAP >130 mmHg)
- Tx hypotension (MAP < 70 mmHg) - Respirations/pulse ox (airway/breathing)
- Maintain airway, clear any secretions
- Administer oxygen or mechanical ventilation if needed - Temperature
- Treat hyperthermia or hypothermia
how to calculate MAP?
= (SBP + 2*DBP)/3
normal = 70-100mmHg
initial management for unconscious pt?
- Obtain IV access and labs
- CBC, glucose, electrolytes, BUN/Cr, LFTs , PT,, ABG, drug screen, ETOH, ammonia - when cause is still unknown, IV and monitor for improvement:
- 50% dextrose in water (D50W), 50 mL x 3-5 min - only if hypoglycemic
- Thiamine 100 mg by slow bolus injection
— Wernicke encephalopathy - MUST before or with glucose
- Naloxone - OD
if the onset/timing of the event for the unconscious pt was abrupt, what is the likely cause?
subarachnoid hemorrhage, seizure, cardiac arrhythmia
if the onset/timing of the event for the unconscious pt was gradual, what is the likely cause?
infectious, space occupying lesion
if the onset/timing of the event for the unconscious pt was fluctuating, what is the likely cause?
recurring seizures, subdural hematoma, metabolic disorders
if the associated sx of the unconscious pt involved focal neurologic changes
what could be the cause?
structural lesion with mass effect or stroke
if the associated sx of the unconscious pt involved HA and vomiting
what could be the cause?
intracranial hemorrhage, increased ICP
if the associated sx of the unconscious pt involved palpitations/chest pain/SOB
what could be the cause?
arrhythmia
if the associated sx of the unconscious pt involved fever or recent illness
what could be the cause?
infection/sepsis
if the associated sx of the unconscious pt involved recent confusion/delirium
what could be the cause?
metabolic process, drug, alcohol, poison
if the associated sx of the unconscious pt involved dizziness/lightheaded
what could be the cause?
hypotension, stroke, arrhythmia, hypoxia
what empiric tx is for possible infection for an unconscious pt?
ceftriaxone and vancomycin
acyclovir
what empiric tx is for possible ingestion for an unconscious pt?
Flumazenil (BZD overdose)
Narcan (opiate overdose)
Gastric lavage/activated charcoal
what empiric tx is for possible increased ICP for an unconscious pt?
Glucocorticoids
Mannitol
Position head of bed elevated 30°