Critical Care Exam 4 (Based on Study
Guide)
What is the Glasgow Coma Scale? - ANS-What is the Glasgow Coma Scale? A tool for
assessing arousal and level of conciousness - guides evaluation of an ill/injured patient
who's status may change quickly. Score of < 8 is indicates need for intubation. Score of
3 or less may be indicative of brain death. *Most sensitive indicator of neurological
status*
Best eye opening response - spontaneous (4), in response to speech (3), in response to
pain (2) no response (1)
Best verbal response - oriented (5) confused (4) inappropriate words (3) garbled sounds
(2) no response (1)
Best motor response - obeys commands (6), localizes stimuli (5), withdrawal from
stimulus (4), abnormal flexion (3) abnormal extension (2) no response (1)
*Intubated patients will be noted to have a score of "1T" for the best verbal response to
recognize that lack of verbalization is due to intubation
*If score is less than 8, intubation is necessary*
What is Intracranial Pressure? - ANS-The pressure within the cranial vault. *Normal is
0-15*
Over 20 is considered elevated (intracranial hypertension)
What are the contents of the cranium? - ANS-Intracranial circulation (Blood),
cerebrospinal fluid, brain parenchyma
Explain cerebral autoregulation - ANS-A protective mechanism in which the brain is able
to control how much blood flow it receives over a range of blood pressures.
Vessels dilate to increase cerebral blood flow, and constrict to decrease cerebral blood
flow.
Damage to brain tissue and BP extremes can impair autoregulation.
,Cerebral vasodilation causes increased ICP by allowing more blood into brain.
Vasodilation can be caused by hypoxia, hypercapnia and acidosis.
*^This is why it is SO important to treat hypoxia and hypercapnia quickly when a TBI
occurs!*
Extremes of blood pressure can also increase ICP, especially when autoregulation is
impaired. Blood pressure elevations occur during coughing, straining, and suctioning.
Explain compensatory mechanisms the brain uses to decrease pressure -
ANS-Shunting of CSF into spinal subarachnoid space
Increased CSF absorption
Decreased CSF production
Shunt of venous blood out of the skull
ICP may remain constant during compensation, but eventually compensation will fail
*When ICP increases, the brain shifts within the skull, and blood supply to the brain
tissue is altered. This can lead to ischemia, anoxic injury, and herniation. This is why
high ICP is so dangerous*
What is herniation? - ANS-The displacement of tissue through structures within the
skull. The most common types are uncal and central, which both result in compression
of the brain stem
How will a patient with increased ICP present? - ANS-*The most sensitive sign is
change in level of consciousness*
-Deterioration in all aspects of neurological functioning
-Restlessness, confusion, combativeness (initial)
-Sluggish/fixed pupillary reactions
-Declined motor function
-Changes in vital signs are a LATE finding
-Cushing's triad: increased systolic, bradycardia, widened pulse pressure (IMPENDING
HERNIATION)
-Increased stimuli to arouse
How is Intracranial pressure monitored? - ANS-ICP monitoring is invasive, monitors
pressure in cranium, helps to calculate CPP, can drain CSF.
Can be preformed with a fluid filled system connected to an external transducer (EVD),
or a fiberoptic system(BOLT).
, Infection must be prevented during ICP monitoring by use of aseptic technique when
handling system!!!
Fiberoptic systems do not require leveling. The external transducer system must be
leveled at the ear canal or outer canthus of the eye. *Leveling is important, if transducer
is too low, it will read a low ICP. If transducer is too high, it will read a high ICP*
-Sustained periods of ICP > 20 are considered significant
-Sustained periods of ICP > 60 are usually fatal
What is CPP? - ANS-Cerebral pulse pressure.
*CPP = MAP - ICP*
Normal reading is *60-100*
CPP of 40-60 = hypoperfusion
CPP <40 = anoxia
Must be over 70 in brain pathology
Altered by increasing or decreasing MAP
Increasing BP can increase cerebral perfusion
What is Brain Tissue Oxygen Monitoring? - ANS-Regional measurement of how much
oxygen a certain area of the brain is receiving. Sensors measure ICP, brain
temperature, and partial pressure of oxygen in brain tissue (PtiO2).
What are the goals of management for increased ICP? - ANS-Reduce ICP, optimize
CPP, and avoid brain herniation.
-Place HOB at 30 degrees to promote cerebral perfusion and facilitate venous drainage
-Maintain head in neutral position to promote jugular outflow
-Avoid hip flexion to decrease intrathoracic pressure
-Assess agitation, because this increases ICP
-Turn q2h and instruct pt to exhale during turns (prevents Valsava maneuver)
-Carry out passive ROM to prevent contractures
-Avoid clustering of activities to prevent long ICP spikes
-Minimize unpleasant stimuli
-Transport patient with ICP monitor
-Check temp frequently because cerebral metabolic rate increases with elevated
temperatures
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