Intracranial Hypertension

last updated: August 3, 2016

ICP

 

ENLS Guidelines (ACLS like course)

 

Anatomy/Physiology

  • 1200-1400g weight of brain

  • 15-20% cardiac output

  • CHO is main energy source (high O2 metabolic rate)

  • 50% of energy goes to ion gradient restoration

  • No energy storage capacity

  • Cerebral blood flow (CBF)

    • 50mL/100g brain tissue per minute

  • about 500mL/day (20cc/hr) of CSF is made

Autoregulation

  • CBF regulate over wide range of MAPS

  • lost when brain is injured

  • metabolic seems to be the main controller of autoregulation: local affect of acid or pH on vascular resistance

  • CO2 dilates

  • CBF increases when paO2 falls below 50

  • CPP (MAP)/ CBF curve

  • Baron, MARIK chest 2000;118:214

 

Intracranial HTN

  • Cushings triad

  • definition: >20mmHg for 5 minutes

  • causes:
    • Venous sinuous thrombosis

    • Increased CSf production

  • Monroe Kellie doctrine

    • "Something has got to give"

    • Brain parenchyma makes up 80%

    • Blood makes up 10%

    • CSF makes up 10%

  • Kernohan’s flase localization sign

  • Lateral Rectus Palsy, CN 6 (LR6 palsy)

    • elevated ICP should be suspected

  • Venous pulsations with crisp disk is the normal look to the optic disk

Cerebral Perfusion Pressure (CPP)

  • >60 if have brain injury

  • >75 in TBI not good

 

Devices: 

Codman

  • Liver patients

 

Bolt

 

EVD

  • into ventricle

  • Allows drainage of CSf

 

Leveled with the tragus

  • when doing better, it's elevated higher and higher to allow the brain to start absorbing CSF

 

P1: arterial pulsation

P2: when higher = noncompliant brain

P3: aortic valve

 

Pathological “A” waves

 

CT SCAN Image

 

Loss of sulci/gyri

 

Acute hydrocephalus

  • Dilated 4th ventricle

 

Poor Gray white differentiation

  • Poor prognosis if seen with first 24hrs

  • EVD done

 

Saggital MRI

 

Star appearance

  • SAH

 

Quadrigeminal cistern

  • Baby's bottom

 

Treatment:

 

 

  • Manage airway

    • Not to be done by someone experienced

    • Reflex sympathetic response to laryngoscopy even if they are in a coma can occur which leads to herniation 

    • have neostigmine if can ready to go if becomes hypotensive

    • Peripheral pressors would be okay emergently if need be

    • RSI even if comatose

    • To blunt rise in ICP: short acting opiate fentanyl

    • Lidocaine not really used anymore (1 study found its effectiveness)

    • succinylcholine okay; has been debated because of the fascinations (Roc 1mg/kg is really the go to drug)

  • CPP>60 (just availed hypotension)

  • osmotic diuresed 1-1.5g/kg, HTS

    • Brain is 80% water

    • Effect occurs rapidly (less than 5 minutes)

    • can't be administered with blood products

    • Caution with renal failure and worsen ICP (rebound)

    • Target osmol 310-320 mOsm/L

    • If osmol gap > 55 then should stop using it

  • hypothermia

    • 34-35

  • CSF drainage

  • Decompressive craniotom

  • Hyperventilation

  • sedation

    • Propofol

    • Thiopental

    • Pentobarbital (Tier 3)

  • HOB >30

    • Don't tight ETT too tight

  • Tier 2: 3% saline 10-20cc/hr

    • do q2hr Na check

    • You can adjust CVVHD To get Na up (155-160)

    • 23.4% HTS over 30 minutes

    • osmotic demyelination syndrome

 

Case example

25y/o female APAP ingwstion

Ammonia very helpful in acute liver failure

  • herniating

    • Raise HOB

    • Hyperventilate (use end tidal)

    • Intubate

    • Manitol

    • Roc, etomidate, neo stick

    • Codman

    • 23.4% HTS

 

Cosmid grid

 

Hypothermia

  • during weaning, see what ICP does; if goes up then recool them

  • might consider getting a CT Brain before rewarming as a prognostication 

    • if looks "tight" than chances are rewarming is going to make things worse​

Measuring Optic Sheath Diameter

... but I would more especially commend the clinician who, in acute diseases, by which the bulk of mankind are cutoff, conducts the treatment better than others.
 
Hippocrates, 400 BC