Critical Care Exam 3 Study Guide
Care of the Patient Experiencing an Intracranial Dysfunction
ICP and CPP: know how to calculate, normal values and what they mean
ICP-intracranial pressure
o normal value: 5-15 mmHg
o any increase in volume or abnormal growth will increase ICP or decrease other volumes resulting in cell
death related to decreased perfusion
o 3 components
brain substance (80%)
CSF (10%)
blood (10%)
CPP-cerebral perfusion pressure
o normal value: 60-100 mmHg
o CPP is an estimate of cerebral blood flow
o intracranial HTN is a value >/=20 mmHg
o Calculation for CPP
MAP-ICP=CPP
Increased ICP:
causes
o increased brain volume
tumor or injury with cerebral edema
o increased CSF
hydrocephalus, obstruction, excess production of CSF
o increased blood
autoregulation loss, hemorrhage, vasodilation, hypercapnia, metabolic demand increase, venous
outflow obstruction
change in circulating volume from decreased Na+, hypo/hyperTN, seizures, or increased
intrathoracic pressure
o extracranial
assessment
o Glasgow Coma Scale (GCS)
normal/highest is 15 & lowest is 3
provide intracranial monitoring with a score of 3-8
o Early Responses to IICP
altered LOC
papilledema
unilateral pupil dilation
HA
vomiting
o Late Responses to IICP
paralysis & parasthesia
Cushing's Triad
systolic HTN
widening pulse pressure
bradycardia
hyperventilation (Cheyne-Stokes breathing pattern)
Herniation of the brain stem is a complication
o Cranial Nerve Testing
Pupillary- optic (2) & oculomotor (3)
Corneal-trigeminal (5) & facial (7)
, Hearing, tinnitus, & dizziness-acoustic (8)
cough & gag reflex-glossopharyngeal (9) & vagus (10)
o Comatose Patients
Oculocephalic Reflex-"Doll's Eyes"
negative reflex if eyes do not move symmetrically or stare straight ahead when head is
moved
C-Spine must be cleared before performing exam
Negative result indicates Medulla or Pons damage
Oculovestibular Reflex-"Cold Caloric"
instill 20-50 ml ice water into ear canal after making sure tympanic membrane is intact
head of bead should be elevated to 30*
If rapid nystagmus-like deviation to affected ear is present the test in normal, if nothing
happens the test is negative
negative result indicates Medulla or Pons damage
intracranial pressure monitoring
o Indications: GCS score of 3-8
o purpose is to indicate responses to therapy & augment neurological assessment
o Methods
Parenchymal/subarachnoid bolt, fiberoptic scope-direct measurement of pressure, but risk of
bleeding & infection
Intraventricular catheter-CSF measures & drainage, but risk of infection & bleeding. This is most
common & most reliable, allowing for intrathecal meds to pass & CSF draining if needed
Epidural probe-no direct measure of drainage but easy to insert with lowest risk of infection
Nursing Care of IICP
o AVOID actions that increase ICP such as deep suctioning, coughing, straining, PEEP, hip flexion, pain, &
abdominal or bladder distention
o AVOID actions that impair cerebral drainage such as supine position, low head, and twisted neck
o make sure airway is patent & PaO2 is >80 mmHg
o keep noise & light to a minimum to avoid excess stimulation
o HOB at 30*
o Keep PaCO2 at 35-4 mmHg & avoid hyperventilation
Treatment of IICP
o Mannitol-osmotic diuretic that acts within 20 minutes to decrease cerebral blood flow & edema
use filter needle to draw up from vial r/t crystalization
o Oxygen-to prevent hypoxia that causes cerebral vasodilation & further increases ICP
o MAP >70
o BP management with fluids, vasoconstrictors, & antihypertensives to keep MA/CPP acceptable
o decrease metabolic demands
Induce hypothermia to a goal of 34-35*C
give Benzos to reduce agitation & restlessness
barbituates, analgesia, NMBA, & sedation as appropriate
o hyperventilation
Cerebral Blood Flow
pressures maintained by autoregulation
o MAP in range of 50-150 mmHg does not alter CBF
Factors that change CBF
o Acidosis/hypoxia r/t cerebral vasodilation
o alkalosis r/t vasoconstriction
o increased metabolic rate=increased CBF
o decreased metabolic rate=decreased CBF
Traumatic brain injury
Care of the Patient Experiencing an Intracranial Dysfunction
ICP and CPP: know how to calculate, normal values and what they mean
ICP-intracranial pressure
o normal value: 5-15 mmHg
o any increase in volume or abnormal growth will increase ICP or decrease other volumes resulting in cell
death related to decreased perfusion
o 3 components
brain substance (80%)
CSF (10%)
blood (10%)
CPP-cerebral perfusion pressure
o normal value: 60-100 mmHg
o CPP is an estimate of cerebral blood flow
o intracranial HTN is a value >/=20 mmHg
o Calculation for CPP
MAP-ICP=CPP
Increased ICP:
causes
o increased brain volume
tumor or injury with cerebral edema
o increased CSF
hydrocephalus, obstruction, excess production of CSF
o increased blood
autoregulation loss, hemorrhage, vasodilation, hypercapnia, metabolic demand increase, venous
outflow obstruction
change in circulating volume from decreased Na+, hypo/hyperTN, seizures, or increased
intrathoracic pressure
o extracranial
assessment
o Glasgow Coma Scale (GCS)
normal/highest is 15 & lowest is 3
provide intracranial monitoring with a score of 3-8
o Early Responses to IICP
altered LOC
papilledema
unilateral pupil dilation
HA
vomiting
o Late Responses to IICP
paralysis & parasthesia
Cushing's Triad
systolic HTN
widening pulse pressure
bradycardia
hyperventilation (Cheyne-Stokes breathing pattern)
Herniation of the brain stem is a complication
o Cranial Nerve Testing
Pupillary- optic (2) & oculomotor (3)
Corneal-trigeminal (5) & facial (7)
, Hearing, tinnitus, & dizziness-acoustic (8)
cough & gag reflex-glossopharyngeal (9) & vagus (10)
o Comatose Patients
Oculocephalic Reflex-"Doll's Eyes"
negative reflex if eyes do not move symmetrically or stare straight ahead when head is
moved
C-Spine must be cleared before performing exam
Negative result indicates Medulla or Pons damage
Oculovestibular Reflex-"Cold Caloric"
instill 20-50 ml ice water into ear canal after making sure tympanic membrane is intact
head of bead should be elevated to 30*
If rapid nystagmus-like deviation to affected ear is present the test in normal, if nothing
happens the test is negative
negative result indicates Medulla or Pons damage
intracranial pressure monitoring
o Indications: GCS score of 3-8
o purpose is to indicate responses to therapy & augment neurological assessment
o Methods
Parenchymal/subarachnoid bolt, fiberoptic scope-direct measurement of pressure, but risk of
bleeding & infection
Intraventricular catheter-CSF measures & drainage, but risk of infection & bleeding. This is most
common & most reliable, allowing for intrathecal meds to pass & CSF draining if needed
Epidural probe-no direct measure of drainage but easy to insert with lowest risk of infection
Nursing Care of IICP
o AVOID actions that increase ICP such as deep suctioning, coughing, straining, PEEP, hip flexion, pain, &
abdominal or bladder distention
o AVOID actions that impair cerebral drainage such as supine position, low head, and twisted neck
o make sure airway is patent & PaO2 is >80 mmHg
o keep noise & light to a minimum to avoid excess stimulation
o HOB at 30*
o Keep PaCO2 at 35-4 mmHg & avoid hyperventilation
Treatment of IICP
o Mannitol-osmotic diuretic that acts within 20 minutes to decrease cerebral blood flow & edema
use filter needle to draw up from vial r/t crystalization
o Oxygen-to prevent hypoxia that causes cerebral vasodilation & further increases ICP
o MAP >70
o BP management with fluids, vasoconstrictors, & antihypertensives to keep MA/CPP acceptable
o decrease metabolic demands
Induce hypothermia to a goal of 34-35*C
give Benzos to reduce agitation & restlessness
barbituates, analgesia, NMBA, & sedation as appropriate
o hyperventilation
Cerebral Blood Flow
pressures maintained by autoregulation
o MAP in range of 50-150 mmHg does not alter CBF
Factors that change CBF
o Acidosis/hypoxia r/t cerebral vasodilation
o alkalosis r/t vasoconstriction
o increased metabolic rate=increased CBF
o decreased metabolic rate=decreased CBF
Traumatic brain injury
