Elevated intracranial pressure: Difference between revisions
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==Background==
==Background==
*Cranial vault is a fixed volume made up of 3 main components
*Monroe-Kellie hypothesis: The total volume of the intracranial space is constant, and comprises 3 main complements, namely the brain tissue (80%), blood (10% or 150mL) and CSF (10% or 150mL). An increase in the volume of any one of the components must necessarily be accompanied by a reduction in that of the other two in order to maintain the fixed total intracranial volume.
**brain tissue (80%) blood (10% or 150L) and CSF (10% or 150mL).  
*CSF is created at a rate of 20mL/hr or 500mL/day.  
*While brain parenchyma is a relatively fixed volume, the blood and CSF are fluids with entranace and egress points into and out of the skull and are primarily affected with changes in ICP.  
*Neuronal injury occurs secondary to vascular compromise to brain cells either by a reduction in cerebral blood flow or direct ischemia. This is an ''' emergency'''  and requires emergent intervention if sustained > 5-10 minutes
**CSF is created at a rate of 20mL/hr or 500mL/day.  
*Neuronal injury occurs secondary to vascular compromise to brain cells either by a reduction in cerebral blood flow or direct ischemia  
**This is an ''' emergency'''  and requires emergent intervention if sustained > 5-10 minutes


==Clinical Signs and Symptoms==
==Clinical Signs and Symptoms==
*Increased ICP generally causes headache (from increased pressure on heavily innervated meninges), Nausea/vomiting, and occasionally optic abnormalities (most notably ocular palsies (CN6 particularly long course intracranially) along with AMS and optic atrophy.
*Headache (from increased pressure on heavily innervated meninges)
*Morning headaches are pathomnemonic (mild hypoventilation during sleeping hours causes increases in cerebreal blood flow)
*Characteristically worse in the morning
*Nausea/vomiting
**Vomiting due to increased ICP typically occurs in the morning
*CN palsies
**CN 6 palsy (false localizing sign)
*Papilloedema (bilaterally blurred optic disc margins)


==Causes==
==Causes==
*As the cranial vault is a fixed volume, Increases in ICP are either due to increased brain tissue (edema), blood (increase inflow or decreased outflow) and CSF (increased inflow/production or decreased outflow) in addition to abnormal mass lesions.
#Increased ICP is due to an increase in any one of the 3 components of the intracranial space (as above)
#Mass lesions
 
##tumor, [[Intracranial Hemorrhage (Main)|hematoma]], air, abscess,foreign body
*Increased brain tissue
#CSF accumulation
**Neoplasms
##Hydrocephalus(obstructive or communicating)
**Cerebral abscess
###Most often obstrcutive via tumor, intraventricular hemorrhage, ventriculutus/meningitis) with compression of CSF outflow
*Increased CSF volume
#Vascular
**Decreased reabsorption
##Either input or output failure
***Obstructive hydrocephalus
###Input failure: increased CBF or CBV due to failed autoregulatoin
***Non-obstructive/communicating hydrocephalus
###Outflow failure: venous congestion or sinus thrombosis
*Increased blood volume
#Cerebral edema
**Intracranial haemorrhage
##vasogenic (vessel damage due to tumor/infection abscess
**Cerebral venous sinus thrombosis
##Cytotoxic (ischemia)
**Failed cerebral autoregulation (causing increases CBF or CBV)
##Hydrostatic: Increased transmural pressure with hydrocephalus
##Hypo-osmolar


==Management==
==Management==
#Ensure data accurate
#Ensure data accurate
##observe for accurate waveforms in arterial and ICP monitors  
##Observe for accurate waveforms in arterial and ICP monitors  
###EVD zeroed at ear, changes with coughing/positioning
###EVD zeroed at ear, changes with coughing/positioning
###Arterial line zeroed at ear (for accurate CPP measurement; although typically level at heart reasonably accurate
###Arterial line zeroed at ear (for accurate CPP measurement; although typically level at heart reasonably accurate
#Assess ABC (as increased ICP often accompanies decline in mental status
#Assess ABC (as increased ICP often causes decline in mental status)
##If need to intubate - ensure measures to avoid coughing/bucking (increases ICP).
##If need to intubate - ensure measures to avoid coughing/bucking (increases ICP)
###[[Lidocaine]] 1% 1ml/kg 1x IV bolus as premedication.
###[[Lidocaine]] 1% 1ml/kg 1x IV bolus as premedication
 
===Goals===
===Goals===
#Keep CPP 60-110mmHg
#Keep CPP 60-110mmHg
##If <110 utilize pressors (levophed or neosynephrine; levophed preferred)
##If <110 utilize pressors (levophed [preferred] or neosynephrine)
##Levophed: start at 4 mcg/min; maximum 20 mcg/min.
##Levophed: start at 4 mcg/min; maximum 20 mcg/min.
##Phenylepherine: start at 0.4 mcg/kg/min; maximum 9 mcg/kg/min.
##Phenylephrine: start at 0.4 mcg/kg/min; maximum 9 mcg/kg/min.
#Keep ICP < 20mmHg (nonsustained temporary elevateions ~<5 minutes ok
#Keep ICP < 20mmHg (nonsustained temporary elevateions ~<5 minutes ok


===Take Stepwise approach to treatment===  
===Take Stepwise approach to treatment===  
====1st (conservative)====
====1st (conservative)====
#Elevate Head of Bed 30-to 45 deg; keep head midline
#Elevate Head of bed to 30-45 deg and keep head midline
##May "sandbag" head of those in c-collar to promote venous drainage(c-collar can restrict venous outlfow)
##May "sandbag" head of those in c-collar to promote venous drainage(c-collar can restrict venous outlfow)
#Control agitation/pain
#Control agitation/pain
##narcotics, benzodiazepines, sedative hypnotics
##Narcotics, benzodiazepines, sedative hypnotics
###Attempt to favor short acting medications to allow neuro exam checks. Versed, Fentanyl and propofol are often appropriate.
###Favor short acting medications to allow neuro exam checks
#Maintain Normocapnia (pCO2 35-40)
###Versed, Fentanyl and propofol are often appropriate.
#Maintain normothermia.
#Maintain normocapnia (pCO2 35-40)
#Maintain normothermia
##Treat shivering
##Treat shivering
###Bear hugger (warms skin temperature)
###Bair hugger (warms skin temperature)
###APAP 650 q6prn for temp >38.5°F  
###APAP 650 q6prn for temp >38.5°F  
#Maintain euvolemia (Input = output)
#Maintain euvolemia
#Maintain euglycemia
 
====2nd (Intervention-short term)====
====2nd (Intervention-short term)====
#hyperventilate to pCO2 ~30mmHg
#Hyperventilate to pCO2 30-35mmHg
##This is short term as patient will equilibrate; is only meant as a temporizing measure. Attempt to wean to normocapnia as soon as able. Further do not overventilate past 25mmHg as may exacerbate damage via cerbral hypoxia (CO2 is primarily involved in autoregulation of cerebral vasculature).
##This is short term as patient will equilibrate; is only meant as a temporizing measure. Attempt to wean to normocapnia as soon as able. Further do not overventilate past 25mmHg as may exacerbate damage via cerbral hypoxia (CO2 is primarily involved in autoregulation of cerebral vasculature).
#Hypertonic fluids
#Hypertonic fluids
##Mannitol 20% 1-1.5g/kg rapid IV bolus (no need for central line) OR
##Mannitol 20% 1-1.5g/kg rapid IV bolus (no need for central line) OR
## 23% Na 30mL over 15 minutes (Needs central line)
## 23% Na 30mL over 15 minutes (Needs central line)
#Consult Neurosurgery (urgent) for possible evacuation or ventricular drainage.
#Consult Neurosurgery (urgent) for possible evacuation or ventricular drainage
##This is especially relevant for mass lesions causing mass effect or in hydrocephalus.
##This is especially relevant for mass lesions causing mass effect, hydrocephalus and intracranial bleeds
 
====3rd (Intervention- long term)====
====3rd (Intervention- long term)====
#Hypertonic fluid maintenance
#Hypertonic fluid maintenance
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####Eventually osmotic pressures will equilibrate over days. requiring higher Na values (rationale behind pushing Na slowly upward as needed rather than pushing hypernatremia to maximum).  
####Eventually osmotic pressures will equilibrate over days. requiring higher Na values (rationale behind pushing Na slowly upward as needed rather than pushing hypernatremia to maximum).  
##Iatrogenic hyperosmolar maintenance  
##Iatrogenic hyperosmolar maintenance  
###Mannitol 20% 0.5g/kg q4hrs with seurm Osm checks q6hrs. (Goal Osm 300-320 mOsm/L)
###Mannitol 20% 0.5g/kg q4hrs with seurm Osm checks q6hrs. (Target osm of 300-320 mOsm/L)
 
====4th (Intervention - Refractory elevation)====
====4th (Intervention - Refractory elevation)====
#Pentobarbital coma
#Pentobarbital coma

Revision as of 05:42, 9 February 2015

Background

  • Monroe-Kellie hypothesis: The total volume of the intracranial space is constant, and comprises 3 main complements, namely the brain tissue (80%), blood (10% or 150mL) and CSF (10% or 150mL). An increase in the volume of any one of the components must necessarily be accompanied by a reduction in that of the other two in order to maintain the fixed total intracranial volume.
  • CSF is created at a rate of 20mL/hr or 500mL/day.
  • Neuronal injury occurs secondary to vascular compromise to brain cells either by a reduction in cerebral blood flow or direct ischemia. This is an emergency and requires emergent intervention if sustained > 5-10 minutes

Clinical Signs and Symptoms

  • Headache (from increased pressure on heavily innervated meninges)
  • Characteristically worse in the morning
  • Nausea/vomiting
    • Vomiting due to increased ICP typically occurs in the morning
  • CN palsies
    • CN 6 palsy (false localizing sign)
  • Papilloedema (bilaterally blurred optic disc margins)

Causes

  1. Increased ICP is due to an increase in any one of the 3 components of the intracranial space (as above)
  • Increased brain tissue
    • Neoplasms
    • Cerebral abscess
  • Increased CSF volume
    • Decreased reabsorption
      • Obstructive hydrocephalus
      • Non-obstructive/communicating hydrocephalus
  • Increased blood volume
    • Intracranial haemorrhage
    • Cerebral venous sinus thrombosis
    • Failed cerebral autoregulation (causing increases CBF or CBV)

Management

  1. Ensure data accurate
    1. Observe for accurate waveforms in arterial and ICP monitors
      1. EVD zeroed at ear, changes with coughing/positioning
      2. Arterial line zeroed at ear (for accurate CPP measurement; although typically level at heart reasonably accurate
  2. Assess ABC (as increased ICP often causes decline in mental status)
    1. If need to intubate - ensure measures to avoid coughing/bucking (increases ICP)
      1. Lidocaine 1% 1ml/kg 1x IV bolus as premedication

Goals

  1. Keep CPP 60-110mmHg
    1. If <110 utilize pressors (levophed [preferred] or neosynephrine)
    2. Levophed: start at 4 mcg/min; maximum 20 mcg/min.
    3. Phenylephrine: start at 0.4 mcg/kg/min; maximum 9 mcg/kg/min.
  2. Keep ICP < 20mmHg (nonsustained temporary elevateions ~<5 minutes ok

Take Stepwise approach to treatment

1st (conservative)

  1. Elevate Head of bed to 30-45 deg and keep head midline
    1. May "sandbag" head of those in c-collar to promote venous drainage(c-collar can restrict venous outlfow)
  2. Control agitation/pain
    1. Narcotics, benzodiazepines, sedative hypnotics
      1. Favor short acting medications to allow neuro exam checks
      2. Versed, Fentanyl and propofol are often appropriate.
  3. Maintain normocapnia (pCO2 35-40)
  4. Maintain normothermia
    1. Treat shivering
      1. Bair hugger (warms skin temperature)
      2. APAP 650 q6prn for temp >38.5°F
  5. Maintain euvolemia
  6. Maintain euglycemia

2nd (Intervention-short term)

  1. Hyperventilate to pCO2 30-35mmHg
    1. This is short term as patient will equilibrate; is only meant as a temporizing measure. Attempt to wean to normocapnia as soon as able. Further do not overventilate past 25mmHg as may exacerbate damage via cerbral hypoxia (CO2 is primarily involved in autoregulation of cerebral vasculature).
  2. Hypertonic fluids
    1. Mannitol 20% 1-1.5g/kg rapid IV bolus (no need for central line) OR
    2. 23% Na 30mL over 15 minutes (Needs central line)
  3. Consult Neurosurgery (urgent) for possible evacuation or ventricular drainage
    1. This is especially relevant for mass lesions causing mass effect, hydrocephalus and intracranial bleeds

3rd (Intervention- long term)

  1. Hypertonic fluid maintenance
    1. Iatrogenic hypernatremia. Use 3% NaCl to maintain na >145 with q6hr serum Na cks.
      1. 3%NS at 1mL/kg/hr appropriate (typically start at 50mL/hr).
      2. May continue to push Na > 145, then >150 then >155 prn to manage ICP
        1. Eventually osmotic pressures will equilibrate over days. requiring higher Na values (rationale behind pushing Na slowly upward as needed rather than pushing hypernatremia to maximum).
    2. Iatrogenic hyperosmolar maintenance
      1. Mannitol 20% 0.5g/kg q4hrs with seurm Osm checks q6hrs. (Target osm of 300-320 mOsm/L)

4th (Intervention - Refractory elevation)

  1. Pentobarbital coma
    1. loading dose: 5-20mg/kg bolus then 4mg;kg/hr titrated to burst supression on EEG.
  2. Induced hypothermia (32-34°F)
    1. Cooling System (ie. Arctic Sunt, Stryker Medi-Therm)
      1. Must perform surveillance cultures (routine blood culture, UA, CXR) every 48 hours since artificially supressing fever.
    2. Shivering protocol
      1. Vecuronium or Pancuronium [1]
  3. Paralytics
    1. Risk of ICU myopathy/neuropathy with long term use.

See Also

References

  1. ↑ Angela Logan et al Optimal Management of Shivering During Therapeutic Hypothermia After Cardiac Arrest Crit Care Nurse 2011;31:e18-e30 http://ccn.aacnjournals.org/content/31/6/e18.full.pdf
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