3. Anesthetic Management of Neurosurgical Emergencies

5/8/2013
Anesthetic Management of Neurosurgical Emergencies
Robert From
Associate Professor
Division of Neuroanesthesia
Assistant Director Main Operating Rooms
Department of Anesthesia
Saturday, May 4, 2013
9:35 ‐ 10:15
Outline
•
Definition of emergency
• Analysis at the University of Iowa
• Review of neurophysiology
• Relevant cases
• Review strategies for brain protection
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Procedures by Service
Jan 1 ‐ Dec 31, 2012
Cardiothoracic
0%
6%
Dentistry
6%
4%
Gynecology
6%
Neurosurgery
28%
Ophthalmology
12%
Surgery
Neuro
2,244
Orthopaedics
Otolaryngology
5%
Radiology
Oto
Orthopaedics
1%
Surgery
11%
21%
18,970 Total
Urology
Miscellaneous
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Emergency Surgical Classification at UIHC
Class
Medical Condition
Time
A
Emergent: life & limb threatening
1 hr
B
Emergent: life & limb threatening
4 hr
C
Urgent: severe complications
8 hr
D
Urgent: severe complications
24 hr
Neurosurgical Emergencies: “A’s & B’s”
498 cases: Jan 1 – Dec 31, 2012
8%
9%
9%
30%
30%
NIR
Craniectomy/
Craniotomy
10%
10%
CRANIECTOMY /
CRANIOTOMY
VENTRICULOSTOMY
VP Shunt
MISCELLANEOUS
VP SHUNT
15%
Ventriculostomy
28%
28%
NEURO INTERVENTIONAL
RADIOLOGY (NIR)
BURR HOLES
30 + 28 +10 + 9 = 77% 3
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Pathology of Emergencies
A
B
Craniectomy
Craniotomy
30%
Ventriculostomy 28%
D
C
VP Shunt 10 %
Neuro
Interventional 9%
Therapies are not mutually exclusive
Neurophysiology ‐ Review
• CMRO2 (ml/100gm/min)
• CBV/CBF (ml/100gm/min)
COUPLED
• CPP (mm Hg)
• ICP
• Skull is rigid box with limited room for expansion • Brain tissue (80%)
• CSF (150 ml in adults) (10%)
• Blood (10%)
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Neurophysiology ‐ Review
•
Any increase in components (blood, brain, CSF) will increase pressure
•
Compensatory mechanisms
•
Displace blood (hyperventilation, MAP)
•
Displace CSF (osmols, ventric, shunt)
•
Increase CSF reabsorption
•
ICP rises rapidly after these are exhausted
•
“Herniation pressure” Above 20‐25 mmHg
Bratton SL: J Neurotrauma 2007:24
What You Can Do
• Avoidable factors contributing to death after neuro compromise
• 26% had airway obstruction
• 22% had hypotension (MAP < 80 mmHg, SBP < 90 mmHg)
• 17% had poorly controlled seizure
Rose, J: BMJ 1977; 2:615‐8
•
•
•
•
•
•
•
Rapid access to the operating room
Hyperventilate??
Blood pressure??
Inhalation agents
Succinylcholine
Cooling
Osmotic therapy: mannitol or saline
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Hyperventilation
• CBF varies directly with PaCO2
• Curve is steep within physiologic
range (35 to 45 mmHg)
• Response is attenuated below
25 mm Hg
• Reduction in CBF is greatest when CBF is high –
like with volatile anesthetics
• Avoid high airway pressure (~35‐45 cm H2O)
Hyperventilate when symptoms of herniation are present
Blood Pressure
CBV / CBF (mL/100 g/mln)
CBV Effect of Autoregulation
ICP
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Plateau Wave
BP
120/70/
140/80
CBV
ICP
ICP
0
Cerebral Edema
• Vasogenic Cerebral Edema (leaky BBB)
 Tumors
 Trauma
 Hematomas
 Infection
 Stroke
 Malignant Hypertension
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Decrease Metabolic Requirements
Intravenous Agents
Inhalation Agents
Patel PM and Drummond JC. Cerebral physiology and the effects of anesthetic drugs.
In: Miller RD, ed. Anesthesia. 7th ed. Philadelphia, Penn: Churchill Livingstone, 2009: 313-317
Paralysis
•
Succinylcholine

Modest increase in ICP from arousal 
Little hazard if C02, BP, and depth of anesthesia is controlled

NPO period may be unknown
• Non‐depolarizing relaxants

Potential to ↑ or ↓ ICP – histamine release or tachycardia

Anti‐seizure medication induce hepatic induction
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Hypothermia
• 7% decrease in CMRO2 for each ° C
• 36.5° C to 34.5° C = 14% decrease


Head trauma, stroke, and cardiac arrest
Hypothermia may be successful if maintained for > 48 hours
Brain Trauma Foundation: www.braintrauma.org

No improvement after craniotomy with aneurysmal subarachnoid hemorrhage
Todd MM: Mild Intraoperative Hypothermia during Surgery for Intracranial Aneurysm. N Engl J Med 2005; 352(2): 135‐145
Mannitol
• Osmotic Effect
 1 mOsm ∆ = 19 mm Hg osmotic pressure
 0.5 g/kg Mannitol over 10 min.  Change from 295 mOsm to 305 mOsm
 Results in a rise in 10 mOsm
 Or 190 mm Hg osmotic pressure sucking fluid out of brain
Editorial by MMT: ANESTHESIOLOGY 2013;118:777
• Diuretic Effect
 Water is drawn from tissue, including RBC
• Hemodynamic Effect/Rheological Effect  Plasma expanding effect
 Reduced cerebrovascular resistance
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Hypertonic Saline
• Intracranial Pressure Reduction

Concentrations range from 1.7% to 30 %; 250 ml

Majority: 7.5% bolus 100 ml to 250 ml
3% infusion
• Na+ to 145 – 155 mEq/L; Osmolality to 300 – 320 mOsm/L
Craniectomy/Craniotomy: Principals Apply to all Emergencies
(Remember therapies are not mutually exclusive)
Bob Woodruff critically wounded by a roadside bomb in Iraq
After his crainiectomy and before his bone flap was replaced
…and how he looks today.
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Ventriculostomy
Management of Acute Shunt Malfunction
Chorid Plexus
Arachnoid Villi
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Management of Acute Shunt Malfunction
• Adult CSF volume 150 ml
• 400 ml produced daily
• Complete turnover about 3 times/day
Management of Acute Shunt Malfunction
•
Failure rates may be 40% in first year
•
Symptoms
nausea
vomiting
seizure
visual changes
sleepy
coma stupor
bradycardia
respiratory arrest
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“Shunt Series”
New shunt
Old Shunt
17 y/o girl who had a shunt placed 13 years ago
Stroke
• 85% are ischemic
Brain tissue surrounding a severely
damaged area may remain viable • 15% are hemorrhagic
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Intervention for Acute Ischemic Stroke
• Tissue plasminogen activator (tPA)
• Use within 3 hours of symptoms onset
• Endovascular therapy for greater than 3 hours

Intra‐arterial thrombolysis within 6 hours ‐ not an FDA approved therapy

Mechanical thrombectomy within 8 hours
Becker K: Current Treatment Options in Neurology 2007, 9: 463‐469
Intervention for Acute Ischemic Stroke
Thrombectomy Devices
A
Trevo
B
Solitaire
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Anesthetic Management for Acute Ischemic Stroke
•
•
Blood pressure less than 220/120 should not be treated unless:

Aortic dissection

Myocardial ischemia

Pulmonary edema

Hypertensive encephalopathy
Consider phenylephrine to push BP above 160 mm Hg systolic
Schneck MJ, et al. Intervention for Acute Ischemic Stroke. In Neurosurgical Emergencies, Loftus CM (Ed.), Thieme Medical Publishers Inc., New York, NY, 2008, pp. 105‐114
Adams HP: Stroke 2003, 34:1056‐1083
Strategies for Brain Protection
• Keep patient on bed/cart (usually for ventriculostomy)
• Hyperventilation
• CPP 70 mm Hg (i.e. MAP of at least 80 mm Hg) – higher for stroke
• Volatile agents increase CBV – used without apparent morbidity
• Paralysis
• Hypothermia – works global, not local
• Osmotic therapy
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bob‐[email protected]
If you had no kidneys would mannitol work?
Yes or No
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Do you have a goal for cerebral perfusion pressure in patients with traumatic brain injury? 17
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Do you use hyperventilation therapy to decrease
ICP in the absence of herniation?
Yes or No
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Head Position
Raise the Head
• 30° to 45° to lower ICP
• ICP is higher when patient is horizontal
• ICP reduced, but CPP maintained
• Onset of action is immediate
• Avoid jugular vein compression (cervical collar)
• Avoid high airway pressures (~ how high is high?)
Management of Acute Shunt Malfunction
•
•
Proximal obstruction – most common

Debris or chorid plexus

Shunt tap won’t work

CSF builds up faster – it has nowhere to go
Distal obstruction

•
Shunt tap produces CSF
Disconnection, fracture, migration
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