Edward Fohrman, anesthesiologist extraordinaire, describes how to use neuroanesthesia when it comes to neurotrauma in this presentation for one of his lectures. Visited EdwardFohrman.com for more information!

1. NEUROANESTHESIA IN
NEUROTRAUMA
Edward B. Fohrman, MD
Northwestern University,
Feinberg School of Medicine
Department of Anesthesiology

2. The Effects of ↑ICP
• Monro-Kellie Doctrine/Hypothesis
• The pressure-volume relationship between
ICP, volume of CSF, blood, and brain tissue,
and cerebral perfusion pressure (CPP).
• Decreased CPP
• Decreased blood flow in marginally
perfused areas
• Herniation of the brain

3. Traumatic Brain Injury (TBI)

4. Traumatic Brain Injury (TBI)

5. Traumatic Brain Injury (TBI)

6. Types of Brain Herniation
a) Subfalcial (cingulate)
b) Uncal
c) Downward (central,
transtentorial)
d) External
e) Tonsillar (Cerebellar)

7. Subfalcine Herniation

8. Uncal Herniation

9. External Herniation

10. Cerebellar (tonsillar) Herniation

11. Indications for CT in Acute Head Injury
• GCS < 13 at any time since injury
• GCS < 15 at 2 hours post injury
• Suspected opened or depressed skull Fx
• Any sign of basal skull Fx
• Post-traumatic Seizure
• Focal Neurologic deficit
• >1 episode of vomiting in pts. >12 y.o.
• Age>65 with LOC, amnesia or coagulopathy

12. Indications for Head CT within 8 hours
• “Dangerous” Mechanism of Injury
• A high-energy head injury:
– pedestrian struck by motor vehicle
– occupant ejected from motor vehicle
– a fall from a height of greater than 1 m or more than five stairs
– diving accident
– high-speed motor vehicle collision
– rollover motor accident
– accident involving motorized recreational vehicles
– bicycle collision
– or any other potentially high-energy mechanism
• Amnesia of events before OR after impact
lasting longer than 30 minutes

13. Shift of Cerebral Autoregulation
normally 50 vs. 70 -150mmHg
RIGHTLEFT
Chronic HTN
Anemia
Sympathetic Stim.
TBI
Hypotension
Carotid Stenosis
AVM adjacent

14. Cerebral Autoregulation in TBI
Neurosurg Focus 25 (4):E7, 2008

15. AVDO2 and CBF in severe TBI
Robertson CS, et al: J Neurosurg 70:222–230, 1989.

16. ∆P/ ∆V = ELASTANCE!!!
Premed?…
DL duration?…

17. Major Influences on CBF
1. Metabolism
• Hypothermia: 1°C = 5-7% ↓ in CBF
2. PaCO2
• Hypercapnia: 1 mmHg PaCO2 = 2-4% ↑ in CBF
3. PaO2
• No increase in CBF until PaO2<60mmHg
4. Viscosity
• Poiseuille’s Law F = (π r4∆P)/8ηL
5. Blood Pressure/CPP/Autoregulation

18. “ THE BRAIN IS TIGHT!!!”

19. Rx for the TIGHT BRAIN
1) CBF/Blood volume
Avoid hypoxemia/hypercapnia/hypotension
Avoid arterial vasodilators
TIVA
Promote autoregulatory vasoconstriction
↓CMRO2 (Burst suppression, Hypothermia)
Mild ↑CPP (w/in autoregulatory range)
Hyperventilate (PaCO2 = 25-30mmHg)
2) Brain Interstitial Fluid
Osmotic Diuresis
Mannitol 0.25-1G/kg 2cc/kg/min of 20% Mannitol
UOP goal 4-5 cc/kg/hr max effect @ 20 min
Hypertonic 3% NaCl 50-100 ml/hr (esp. if pt. is hyponatremic)
Forced (Non Osmotic) Diuresis - Lasix 0.25-1mg/kg 15 min before
mannitol…???
Fluid Restriction?

20. Rx for the TIGHT BRAIN
3) Venous Blood Drainage
– ↓Intra-Abdominal Pressure (positioning, bucking)
– ↓Intra-Thoracic Pressure (↓Vt,↑RR, avoid PEEP)
– Head Up (10-300 Reverse T-Berg/ dbl. check head position
for optimal venous drainage
– (straight neck veins, chin/chest room)
– Avoid Venodilators (NTG)
4) CSF
– Drain off CSF directly by surgeon, or via EVD/Lumbar drain
– 15-20 ml (per surgeon)
– Decrease CSF formation with Lasix
– Stop direct stimulants of CSF formation
(Des>>Sevo&Iso>Propofol)

21. Hypertonic Saline (3% NaCl)
• May be useful in refractory ICP
• CSW (cerebral salt wasting)
• Cases that require quick restoration of
intravascular volume & reduction of ICP
• More studies are needed
• Rate? CPM?

22. Thank You Very Much…
TGIF!!!