TBI: Secondary Injury. What does it produce? - Answer-Secondary: Occurs following the initial insult and is a result of changes in intracranial hemodynamics. Produces death or disability via either herniation of inadequate cerebral perfusion.
Monroe- Kellie Hypothesis - Answer-If one increases t...
N- 400 Exam #3 Questions with Correct
Answers
TBI: Secondary Injury. What does it produce? - Answer-Secondary: Occurs following
the initial insult and is a result of changes in intracranial hemodynamics. Produces
death or disability via either herniation of inadequate cerebral perfusion.
Monroe- Kellie Hypothesis - Answer-If one increases then another has to decrease so
that the total volume stays the same and the ICP remains <15mmHg
Blood= 10%
CSF= 10%
Brain= 80%
Cerebral Blood Flow (CBF) - Answer--the brain requires 15-20% of the CO and 15% of
the body's total O2 demands.
-CBF is regulated by metabolic activity (temperature, agitation, etc)
-CBF must overcome ICP to perfuse the brain (ICP acts as a force resisting blood flow
into the cranium)
Which of the following produces cerebral vasodilation and increased CBP? - Answer-A.
Hyperoxemia
B. Hypocarbia (low PCO2)
C. Hypercarbia (high PCO2)
D. Hypothermia
Answer:
C. Hypercarbia
Is increased CBP a good thing? - Answer-A. Yes, always
B. Usually
C. Not necessarily- it depends on ICP
D. Not in TBI
Answer:
C. Not necessarily it depends on the impact on ICP
ABG effects on ICP and CBF - Answer--decreased pO2-> ischemia
-decreased pO2 or increased pCO2-> acidosis-> cerebral vasodilation-> increased CBF
(but that may increase ICP)
-decreased pCO2 -> alkalosis (hyperventilation)-> vasoconstriction-> decreased CBF
(decreased ICP)
ABG's can be used to control ICP but at what cost? Ischemia
,Cerebral Compensatory Mechanisms - Answer-Protect the brain from cerebral HTN (inc
ICP) and maintain cerebral blood flow.
-Compliance
-CSF shunt
-Autoregulation
TBI: Compliance - Answer-The ability of the brain to tolerate increases in intercranial
volume without associated pressure increases (ICP).
-As ICP increases, compliance decreases
-The smallest stimuli can produce large/sustained increases in ICP
-Know that even small increases in volume are creating large changes in pressure= loss
of compliance
As a neuro nurse should you cluster nursing care? - Answer-No! due to loss of
compliance
With loss of autoregulation, low BP will increase ICP, but high BP will decrease ICP. T
or F? - Answer-A. True
B. False
Answer:
B. False
High or low BP can both cause the same results: increased ICP
Autoregulation - Answer-The maintenance of constant cerebral blood flow in spite of
wide ranges in arterial pressure.
-Functions within a MAP of 50-150mmHg (systemic MAP)
-Often compromised in brain injury so that variations in MAP result in variations in CBF
*higher MAP is not always better*
Patho: Effects of Brain Injury on ICP and Cerebral Perfusion - Answer-Brain injury-->
local or global ischemia
-lactic acidosis--> cell wall breakdown, lipid peroxidation, and liberation of biochemical
mediators
-excitatory amino acids--> Ca+ influx
THIS LEADS TO:
-loss of Na/K pump--> swelling and rupture (cerebral edema)--> inc ICP
-Loss of compliance--> inc ICP
-loss of autoregulation--> fluctuations in CBF
Three Dangers of Intercranial HTN (Elevated ICP) - Answer--herniation
-decreased CPP
-decreased Brain Tissue Oxygenation pbtO2
,**All result in cerebral ischemia**
What are the 5 components of a neuro exam? - Answer--LOC
-PERRLA
-Motor
-Respiratory
-VS
Which component is most significant when monitoring for ICP changes? - Answer-A.
LOC
B. Vital Signs
C. Pupil size and response
D. Respiratory Changes
Answers:
A. LOC (first indiciation of an increase in ICP)
What are the other S/S of increased ICP? - Answer--posturing
-pupil changes
-dec reflexes
-yawning (brain needs more O2)
-seizures
-cushings triad (dec. HR, inc BP, dec RR) & respiratory changes
**cushings and respiratory changes are late signs**
When managing a patient with TBI, the recommended goal is to keep ICP less than
what value? - Answer-A. 10
B. 15
C. 20
D. 30
Answer:
C. 20
ICP Monitoring - Answer-Types of Systems:
-catheter- transducer system
-fiberoptic catheter system
Variety of Locations for Monitoring:
-epidural
-subarachnoid
-interparenchymal (in the brain tissue)
-interventicular
Which is the best and preferred location for a ICP monitor? - Answer-Interventricular
because we can also drain from here and no other systems can drain CSF.
, ICP Monitoring System - Answer--high pressure tubing
-preservative free saline in the tubing (hand filled, no flush bag, no flush device, no
heparin)
-transducer (taped to head) and monitor--> no IV pole
-drainage system
Where is the transducer in an ICP monitoring system supposed to be positioned at? -
Answer-Level @ the foramen of monroe= corner of the eye and the top of the ear-
directly on the head
With how low of an ICP can herniation occur? - Answer--Herniation may occur in some
pts as low as 15mmHg--> but we dont consider it elevated until it is greater than 20
ICP Waveform Interpretation - Answer-P1 (first peak) should be the highest peak/ wave
and each subsequent bump should decrease until the next P1.
If the other peaks (P2 or P3) are higher or at the same level then the brain has poor
compliance...
ICP Waveform Types - Answer--C Waves: Small rhythmic spikes (waves) q 4-8
minutes. Related to respirations. Insignificant
-B Waves: Sharp spikes up to 70mmHg that may occur q 1-2 minutes. Indicate low
compliance
-A Waves aka Plateau Waves: Sharp increases of 30-70 mmHg in an already elevated
ICP. May last 2-20 minutes. May see clinical signs. If true plateau waves it will self
resolve but don't wait for it to come down
Draining CSF from ICP Catheters - Answer-Closed System; remember to zero newer
systems by hanging the bag 20 cm above the foramen of monroe.
Three Dangers of Elevated ICP - Answer-1. Herniation
2. Dec CPP
3. Dec BTO
Supratentorial Herniation - Answer-Uncal: Brain tissue is being pushed down through
the tentorium against the brain stem. Will see pupil changes
Midline Shift: Brain is shifted over from one side to the other. Not to bad
Transcalvarial: Brain is pushed out through a hole or break in the skull.
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