Cerebral PharmacologyCerebral Pharmacologyand Anesthesiaand Anesthesia

for Supratentorial for Supratentorial CraniotomyCraniotomy

Mani K.C Vindhya M.DMani K.C Vindhya M.D

Asst Prof of AnesthesiologyAsst Prof of Anesthesiology

Nova Southeastern UniversityNova Southeastern University

Introduction to Cerebral Pharmacology. Introduction to Cerebral Pharmacology. In addition to anesthetic In addition to anesthetic agents andagents and neuromuscular junction blockers, don’t forget:neuromuscular junction blockers, don’t forget: Drugs to decrease brain interstitial fluid Drugs to decrease brain interstitial fluid

Dexamethasone (edema around solid brain tumors) Dexamethasone (edema around solid brain tumors) Mannitol and hypertonic saline (osmotic diuretics) Mannitol and hypertonic saline (osmotic diuretics) Furosemide (loop diuretic) Furosemide (loop diuretic)

Antibiotics Antibiotics – usually two for intracranial neuroanesthesia– usually two for intracranial neuroanesthesia Nafcillin or oxacillin (or vancomycin, if penicillin allergic) Nafcillin or oxacillin (or vancomycin, if penicillin allergic) Gentamicin Gentamicin

Qualities of an Ideal Neuroanesthetic Qualities of an Ideal Neuroanesthetic

Maintenance of mean arterial pressure and cerebral Maintenance of mean arterial pressure and cerebral perfusion pressure perfusion pressure

Decrease in intracranial pressure (ICP) Decrease in intracranial pressure (ICP) Decrease in cerebral metabolic rate coupled with decrease in Decrease in cerebral metabolic rate coupled with decrease in

cerebral blood flow cerebral blood flow Decrease in CSF volume (production < reabsorption) Decrease in CSF volume (production < reabsorption) No inhibition of cerebral autoregulation No inhibition of cerebral autoregulation No expansion of closed air spaces No expansion of closed air spaces Rapid emergence Rapid emergence Anticonvulsant Anticonvulsant Lack of toxicity to major organ systems Lack of toxicity to major organ systems Cerebroprotective (or at least not harmful) Cerebroprotective (or at least not harmful) Compatibility with neuromonitoring (such as SSEP’s) Compatibility with neuromonitoring (such as SSEP’s)

Maintenance of Mean Arterial Pressure and Cerebral Perfusion Pressure

CPP = MAP - ICP (or CVP, whichever is greater)

Change in MAP Inhaled Anesthetics Intravenous Anesthetics

Increase N2O

Little change Etomidate Opioids

Decrease Halothane Thiopental Isoflurane Propofol Desflurane

Sevoflurane

Large Decrease Enflurane

Decrease in ICP and Cerebral Blood Flow Decrease in ICP and Cerebral Blood Flow All inhaled anesthetics (in high concentrations) increase All inhaled anesthetics (in high concentrations) increase

CBF. CBF. All IV anesthetics (except ketamine) decrease CBF. All IV anesthetics (except ketamine) decrease CBF.

The volatile agents have a biphasic effect on CBF in The volatile agents have a biphasic effect on CBF in normal subjects normal subjects

Effects of volatile agents on CBF and CMR in normal Effects of volatile agents on CBF and CMR in normal subjects (coupling intact):subjects (coupling intact):

CBF

CMR

Effects of volatile agents on CBF if coupling is Effects of volatile agents on CBF if coupling is impaired or if CMR is already suppressed:impaired or if CMR is already suppressed:

CMR

CBF

Decrease in Cerebral Metabolic Rate (CMRO2) coupled with Decrease in Cerebral Metabolic Rate (CMRO2) coupled with decrease in Cerebral Blood Flow (CBF)decrease in Cerebral Blood Flow (CBF)

Decrease in Cerebral Metabolic Rate (CMRO2) Decrease in Cerebral Metabolic Rate (CMRO2) IV anesthetics – coupled with decreased CBF (metabolic effect) IV anesthetics – coupled with decreased CBF (metabolic effect) Volatile inhaled anesthetics - “uncoupling” of CBF from Volatile inhaled anesthetics - “uncoupling” of CBF from

CMRO2 in high concentrations CMRO2 in high concentrations Only 2 anesthetics increase CMRO2 (coupled with an increase in Only 2 anesthetics increase CMRO2 (coupled with an increase in

CBF):CBF): Ketamine Ketamine Nitrous oxide (N2O) Nitrous oxide (N2O)

Effects of Dexmedetomidine on CBF and CMR Effects of Dexmedetomidine on CBF and CMR Dexmedetomidine decreases CBF and CBF velocity in Dexmedetomidine decreases CBF and CBF velocity in

humans. humans. Dexmedetomidine did not reduce CMR in an animal Dexmedetomidine did not reduce CMR in an animal

model. model. A 2008 study showed that dexmedetomidine decreases A 2008 study showed that dexmedetomidine decreases

both both CBF velocity and CMR in humans CBF velocity and CMR in humans

• Decrease in CSF Production Relative to Reabsorption.

– A decrease in CSF volume would tend to decrease intracranial volume and ICP.

– Effects of anesthetics on CSF secretion and absorption

ANESTHETIC SECRETION ABSORPTION

Halothane Decrease Decrease

Enflurane Increase Decrease

Isoflurane --- Increase

Desflurane Increase (hypocapnia only) ---

Fentanyl --- Increase

Etomidate Decrease Increase

No Inhibition of Cerebral Autoregulation No Inhibition of Cerebral Autoregulation Autoregulation is intact with IV agents (i.e. thiopental, Autoregulation is intact with IV agents (i.e. thiopental,

propofol, fentanyl) propofol, fentanyl) In high concentrations, all volatile inhaled anesthetics In high concentrations, all volatile inhaled anesthetics

impair autoregulation impair autoregulation

No Expansion of Closed Air Spaces No Expansion of Closed Air Spaces N2O = the only anesthetic that expands closed air spaces N2O = the only anesthetic that expands closed air spaces

Intracranial air pockets Intracranial air pockets Pneumocephalus Pneumocephalus Air emboli (venous or arterial) Air emboli (venous or arterial)

Teaching Points: Teaching Points: Don’t turn on N2O at the end of case Don’t turn on N2O at the end of case

(but perhaps O.K. to leave it on during case).(but perhaps O.K. to leave it on during case). Don’t use in patients after recent craniotomy (i.e., air Don’t use in patients after recent craniotomy (i.e., air

pockets on CT scan).pockets on CT scan).

. Rapid Emergence from Anesthesia

(Lower Blood:Gas Solubility)

Inhaled Agent B:G Solubility

Halothane 2.4

Enflurane 1.9 (cf. MAC = 1.7)

Isoflurane 1.4 (cf. MAC = 1.2)

Sevoflurane 0.68

Nitrous oxide 0.47

Desflurane 0.42

Anticonvulsant Activity = desirable property

Anesthetic Type Only Both pro- and Only proconvulsant anticonvulsant anticonvulsant activity activity activity

Intravenous Methohexital Etomidate* Thiopental Narcotics Diazepam Midazolam Ketamine

Propofol*

Methohexital

Inhalational Nitrous oxide Enflurane* Isoflurane (?) Halothane Desflurane (?) Sevoflurane*

Isoflurane (?)

Desflurane (?)

Numerous case reports of convulsion-like muscle activity during Numerous case reports of convulsion-like muscle activity during induction and emergence from anesthesia with:induction and emergence from anesthesia with: Sevoflurane Sevoflurane Enflurane Enflurane Etomidate Etomidate Propofol Propofol

To prevent peri-operative drug-induced seizures in epileptic To prevent peri-operative drug-induced seizures in epileptic patients patients Continue anticonvulsant therapy. Continue anticonvulsant therapy. Consult with the patient’s neurologist to discuss management. Consult with the patient’s neurologist to discuss management. Avoid etomidate. Avoid etomidate. Do not use sevoflurane routinely in epileptic patients. Do not use sevoflurane routinely in epileptic patients.

Limit maximum concentration to < 1.5 MAC. Limit maximum concentration to < 1.5 MAC.

Lack of toxicity to major organ systems Lack of toxicity to major organ systems 1. All of the volatile inhaled anesthetics can form toxic metabolites in CO2 absorbents 1. All of the volatile inhaled anesthetics can form toxic metabolites in CO2 absorbents

(baralime > soda lime).(baralime > soda lime). A = compound A (vinyl compound produced by sevoflurane)A = compound A (vinyl compound produced by sevoflurane) B = BCDFE (vinyl compound produced by halothane)B = BCDFE (vinyl compound produced by halothane) C = carbon monoxide (formed by pungent volatile anesthetics in the following rank C = carbon monoxide (formed by pungent volatile anesthetics in the following rank

order)order) D = desflurane > E = enflurane >F = Forane R (isoflurane)D = desflurane > E = enflurane >F = Forane R (isoflurane)

Many anesthetics are associated with potential organ toxicity: Many anesthetics are associated with potential organ toxicity: Sevoflurane – renal toxicity might be caused by: compound A from CO2 Sevoflurane – renal toxicity might be caused by: compound A from CO2

absorbents absorbents fluoride ion from hepatic metabolism fluoride ion from hepatic metabolism

Halothane > enflurane > isoflurane > desflurane Halothane > enflurane > isoflurane > desflurane Hepatotoxicity in proportion to hepatic metabolism Hepatotoxicity in proportion to hepatic metabolism

Nitrous oxide – bone marrow toxicity Nitrous oxide – bone marrow toxicity Etomidate Etomidate

Adrenocortical suppression Adrenocortical suppression Propylene glycol toxicity caused by diluent Propylene glycol toxicity caused by diluent

Cerebroprotective (or at least not harmful) Cerebroprotective (or at least not harmful) Thiopental = the “gold standard” for cerebral Thiopental = the “gold standard” for cerebral

protection at the present time (i.e., during clipping of protection at the present time (i.e., during clipping of an intracranial aneurysm)an intracranial aneurysm)

Three agents may be harmful so far as cerebral Three agents may be harmful so far as cerebral protection is concerned:protection is concerned:

Ketamine Ketamine Nitrous oxide Nitrous oxide Etomidate Etomidate Compatibility with Neuromonitoring Compatibility with Neuromonitoring (such as (such as

somatosensory evokedsomatosensory evoked potentials) potentials)

Three kinds of evoked potentials: Three kinds of evoked potentials:

Evoked Potential Latency Anesthetic Interaction

Brainstem auditory evoked response 2 msec Barely affected (BAER)

Somatosensory evoked potentials, 20 msec Somewhat affected SSEPs (median nerve)

Somatosensory evoked potentials, 40 msec Somewhat affected SSEPs (posterior tibial nerve)

Visual evoked response (VER) 70-100 msec Very variable under anesthesia

Effect of isoflurane on upper extremity SSEPs Effect of isoflurane on upper extremity SSEPs

Summary of effects of anesthetics on SSEPs:Inhaled anesthetics – dose-related decrease in amplitude and

increase in latencyLess than 1 MAC volatile agent

Nitrous oxide – profound depressant effect on SSEPs, especially when used in combination with volatile agent

Intravenous agents:Intravenous agents: Propofol and thiopental – small decrease in amplitude Propofol and thiopental – small decrease in amplitude and increase in latency. Propofol is commonly used for TIVA (total IV and increase in latency. Propofol is commonly used for TIVA (total IV

anesthetic) technique.anesthetic) technique. Opioids – negligible effect on SSEP’s Opioids – negligible effect on SSEP’s Ketamine and etomidate – increase SSEP amplitude. Ketamine and etomidate – increase SSEP amplitude. (Etomidate is exceptional. It increases SSEP amplitude but decreases (Etomidate is exceptional. It increases SSEP amplitude but decreases

BAEP amplitude).BAEP amplitude). Summary. Six I’s that inhibit SSEP’s: Summary. Six I’s that inhibit SSEP’s: Inhaled anesthetics (isoflurane and nitrous oxide) Inhaled anesthetics (isoflurane and nitrous oxide) IV anesthetics (to a lesser extent than inhaled anesthetics). IV anesthetics (to a lesser extent than inhaled anesthetics). Ketamine and etomidate are the exceptions; they increase amplitude.Ketamine and etomidate are the exceptions; they increase amplitude. Ischemia or hypoxia – anywhere from limb to cortex Ischemia or hypoxia – anywhere from limb to cortex Injury – anywhere from limb to cortex Injury – anywhere from limb to cortex Ice cold temperatures – < 34.5 oC “Incompetence” Ice cold temperatures – < 34.5 oC “Incompetence”

I.V. Induction of Anesthesia for Intracranial Neurosurgery I.V. Induction of Anesthesia for Intracranial Neurosurgery

Typical induction agents Typical induction agents Thiopental, propofol, or etomidate =suitable I.V. Thiopental, propofol, or etomidate =suitable I.V.

induction agents induction agents Fentanyl or sufentanil Fentanyl or sufentanil

– – as narcotic analgesics to supplement as narcotic analgesics to supplement Lidocaine IV – to blunt hypertensive and ICP response to Lidocaine IV – to blunt hypertensive and ICP response to

intubationintubation Neuromuscular junction blockers –Neuromuscular junction blockers –

rocuronium, vecuronium, or succinylcholine (with prior rocuronium, vecuronium, or succinylcholine (with prior defasciculating dose of a competitive NMJB)defasciculating dose of a competitive NMJB)

Succinylcholine for intracranial neurosurgerySuccinylcholine for intracranial neurosurgery 1. Increased CBF and ICP in dogs1. Increased CBF and ICP in dogs 2. Succinylcholine has been postulated to increase ICP by 2. Succinylcholine has been postulated to increase ICP by

causing muscle afferent activity and stimulation of muscle causing muscle afferent activity and stimulation of muscle spindle fibers (innervated by A-gamma fibers).spindle fibers (innervated by A-gamma fibers).

A more recent study in patients with neurologic injury A more recent study in patients with neurologic injury showed that succinylcholine did not change ICP, CBF showed that succinylcholine did not change ICP, CBF velocity, or EEG activity. velocity, or EEG activity.

The increase in ICP induced by succinylcholine can be The increase in ICP induced by succinylcholine can be blocked with a defasciculating dose of NMJ blockerblocked with a defasciculating dose of NMJ blocker

Teaching points: Teaching points: Don’t use succinylcholine if it’s contraindicated Don’t use succinylcholine if it’s contraindicated

(i.e., hemiplegia).(i.e., hemiplegia). If OK, use succinylcholine if you’re at all worried If OK, use succinylcholine if you’re at all worried

about the airway. about the airway. Use a defasciculating dose of a competitive Use a defasciculating dose of a competitive

neuromuscular junction blocker if you plan to use neuromuscular junction blocker if you plan to use succinylcholine succinylcholine

Maintenance of Anesthesia: How do the anesthetics stack up? Maintenance of Anesthesia: How do the anesthetics stack up?

Some agents we just don’t use: Some agents we just don’t use: Ketamine Ketamine

Only cerebrovasodilating IV agent Only cerebrovasodilating IV agent Increases CSF volume Increases CSF volume May cause neuronal damage due to its action on May cause neuronal damage due to its action on

glutamate (N-methyl-D-aspartate, NMDA) receptors glutamate (N-methyl-D-aspartate, NMDA) receptors Halothane Halothane

Most cerebrovasodilating inhaled agent (cortical CBF) Most cerebrovasodilating inhaled agent (cortical CBF) Hepatotoxicity limits use in adults Hepatotoxicity limits use in adults

Enflurane – no longer in our O.R. Enflurane – no longer in our O.R. Second most cerebrovasodilating inhaled agent, after Second most cerebrovasodilating inhaled agent, after

halothane halothane Increases CSF volume Increases CSF volume Epileptogenic (esp. with hypocarbia) Epileptogenic (esp. with hypocarbia)

Isoflurane, Sevoflurane, & Desflurane Isoflurane, Sevoflurane, & Desflurane Bad Points: Bad Points:

Decrease MAP (high concentrations) Decrease MAP (high concentrations) Increase CBF and ICP (high conc’s) Increase CBF and ICP (high conc’s) Decrease CPP (high concentrations) Decrease CPP (high concentrations) Inhibit autoregulation (> 1% isoflurane) Inhibit autoregulation (> 1% isoflurane)

Good Points: Good Points: Decrease CMRO2 Decrease CMRO2 No expansion of closed air spaces No expansion of closed air spaces Easily titratable Easily titratable

Desflurane Desflurane Bad Points: Bad Points:

Decreases MAP (so former PDR’s prohibited its use in intracranial neurosurgery) Decreases MAP (so former PDR’s prohibited its use in intracranial neurosurgery) Maximum of 0.8 MAC recommended in current PDR Maximum of 0.8 MAC recommended in current PDR Increased lumbar CSF pressure in one study but not in another more recent study Increased lumbar CSF pressure in one study but not in another more recent study

in the setting of hyperventilation.in the setting of hyperventilation. ! Carbon monoxide (CO) production in CO2 absorbent is a concern.! Carbon monoxide (CO) production in CO2 absorbent is a concern.

Coughing and bucking on emergence Coughing and bucking on emergence Very Good Point: Very Good Point:

Rapid emergence (allows for rapid wake-up at end of case) Rapid emergence (allows for rapid wake-up at end of case)

Sevoflurane Sevoflurane Bad Points: Bad Points:

EEG seizure activity has led to recommendation that EEG seizure activity has led to recommendation that sevoflurane not be used routinely in epileptics sevoflurane not be used routinely in epileptics

Possible nephrotoxicity is a concern: Possible nephrotoxicity is a concern: Fluoride ion production from hepatic metabolism Fluoride ion production from hepatic metabolism Compound A production from CO2 absorbent Compound A production from CO2 absorbent

Should not use for > 10 MAC hours (i.e., long neuro Should not use for > 10 MAC hours (i.e., long neuro cases) cases)

Good Points: Good Points: Rapid emergence (perhaps use at end of case) Rapid emergence (perhaps use at end of case) Pleasant odor (less coughing and bucking?) Pleasant odor (less coughing and bucking?) Favorable regarding CBF and autoregulation Favorable regarding CBF and autoregulation

Nitrous Oxide Nitrous Oxide Bad points: Bad points: Increases CBF more than isoflurane on a MAC to MAC basis Increases CBF more than isoflurane on a MAC to MAC basis Increases CMRO2 (only I.A. that does) Increases CMRO2 (only I.A. that does) Expands closed air spaces (only I.A. that does) Expands closed air spaces (only I.A. that does) Tends to cause nausea and vomiting Tends to cause nausea and vomiting May cause neuronal damage due to its action on glutamate (N-methyl-May cause neuronal damage due to its action on glutamate (N-methyl-

D-aspartate, NMDA) receptors D-aspartate, NMDA) receptors Good Points: Good Points:

MAP is maintained. MAP is maintained. Rapid emergence Rapid emergence Easily titratable Easily titratable Many neuroanesthesiologists routinely used it in the past Many neuroanesthesiologists routinely used it in the past

! No difference in outcome of elective supratentorial craniotomy! No difference in outcome of elective supratentorial craniotomy

Propofol Propofol Good Points: Good Points:

Decreases CBF Decreases CBF Decreases CMRO2 Decreases CMRO2 Autoregulation is preserved. Autoregulation is preserved. Apparent antiemetic action Apparent antiemetic action

Bad Points: Bad Points: Decreases MAP Decreases MAP

May have delayed emergence relative to inhalational May have delayed emergence relative to inhalational techniques techniques

Anesthetic Opioids (Fentanyl, sufentanil, alfentanyl, remifentanyl) Anesthetic Opioids (Fentanyl, sufentanil, alfentanyl, remifentanyl) Good Points: Good Points:

Little change in CBF Little change in CBF Less decrease in MAP Less decrease in MAP Little change in CBF Little change in CBF Autoregulation is preserved. Autoregulation is preserved.

Bad Points: Bad Points: Nausea and vomiting = a frequent S.E. Nausea and vomiting = a frequent S.E.

Fentanyl was thought to be better than sufentanil or alfentanyl, based on their Fentanyl was thought to be better than sufentanil or alfentanyl, based on their effects on MAP and CPP effects on MAP and CPP

Sufentanil does not increase ICP in patients with brain injury so long as MAP is Sufentanil does not increase ICP in patients with brain injury so long as MAP is maintained maintained

Remifentanyl Remifentanyl Good Point: A logical choice for rapid emergence Good Point: A logical choice for rapid emergence Bad Points: Bad Points:

Severe hypertension on emergence Severe hypertension on emergence (recommended to give MSO4 prior to DC’ing (recommended to give MSO4 prior to DC’ing remifentanyl) remifentanyl)

? High incidence of post-op nausea and vomiting ? High incidence of post-op nausea and vomiting

Anesthetic Management of Intracranial Neurosurgical Cases Anesthetic Management of Intracranial Neurosurgical Cases Reasonable Maintenance Regimens for Intracranial Neuroanesthesia Reasonable Maintenance Regimens for Intracranial Neuroanesthesia

(going from routine to desperate). (going from routine to desperate). N2O + isoflurane (½%) + fentanyl N2O + isoflurane (½%) + fentanyl

N2O = the first agent to go if there’s brain swelling or venous air emboli or N2O = the first agent to go if there’s brain swelling or venous air emboli or ischemia danger (i.e. aneurysm or head trauma) ischemia danger (i.e. aneurysm or head trauma)

MAC equivalents of sevoflurane or desflurane might also be substituted for MAC equivalents of sevoflurane or desflurane might also be substituted for isoflurane. isoflurane.

Sufentanil could be substituted for fentanyl. Sufentanil could be substituted for fentanyl. Isoflurane (1%) + fentanyl Isoflurane (1%) + fentanyl Isoflurane (½%) + propofol + fentanyl Isoflurane (½%) + propofol + fentanyl

Volatile agents are next to go if intractable ICP or brain swelling Volatile agents are next to go if intractable ICP or brain swelling Total IV anesthetic: Propofol + fentanyl Total IV anesthetic: Propofol + fentanyl Barbiturate coma -- for intractible brain swelling or cerebral protection during Barbiturate coma -- for intractible brain swelling or cerebral protection during

aneurysm clipping (titrated to EEG burst suppression):aneurysm clipping (titrated to EEG burst suppression): Thiopental Thiopental Pentobarbital Pentobarbital

Reasonable Muscle Relaxants for Maintenance Reasonable Muscle Relaxants for Maintenance of NM Blockade of NM Blockade

Vecuronium Vecuronium Rocuronium Rocuronium Pancuronium – increases HR Pancuronium – increases HR Cis-atracurium: Cis-atracurium:

No histamine release (different from atracurium) No histamine release (different from atracurium) An epileptogenic metabolite, laudanosine An epileptogenic metabolite, laudanosine

Special Cases in Neuroanesthesia Special Cases in Neuroanesthesia

• The ways to decrease intracranial volume and pressure apply in typical intracranial neuroanesthetic cases (i.e., supratentorial craniotomies).

Three components “Bad” Things that Ways to Decrease inside the skull Increase ICV and ICP ICV and ICP

Brain (80% of ICV) Surgical excision ! Neurons, glia, Tumor Evacuation of hematoma

extravasated cells Hemorrhage Temporal lobe Head injury decompression

! Interstitial fluid Edema Mannitol Hypertonic saline Furosemide Dexamethasone

CSF (8% of ICV) Obstructive Spinal drain hydrocephalus Ventriculostomy

Blood volume (12% of ICV) Increase CBF: Decrease CBF:

! Arterial side Hypoventilation/ Hyperventilation/ hypercarbia mild hypocarbia Hypoxia Avoid hypoxia Heavy pre-medication Anesthetic choice Hyperthermia Avoid hyperthermia Inhibit cerebral venous Improve cerebral venous

! Venous side drainage drainage

Transphenoidal Hypophysectomy = an exception. Transphenoidal Hypophysectomy = an exception.

For resection of tumorFor resection of tumor confined to pituitary: confined to pituitary: No furosemide or mannitol No furosemide or mannitol Dexamethasone (solid brain tumor) Dexamethasone (solid brain tumor) Spinal drain (to put air or NSS in, not to take CSF out) Spinal drain (to put air or NSS in, not to take CSF out) No hyperventilation No hyperventilation

Quirk of Anesthesia after Recent Craniotomy Quirk of Anesthesia after Recent Craniotomy Avoid N2O if air is inside skull on CT scan Avoid N2O if air is inside skull on CT scan

Quirks of Head Trauma (ABC’s of TBI) Quirks of Head Trauma (ABC’s of TBI) Airway. Safely get control. Airway. Safely get control. Blood pressure. Avoid hypotension (SBP < 90 mm Hg) if possible, or Blood pressure. Avoid hypotension (SBP < 90 mm Hg) if possible, or

correct it immediately. correct it immediately. CO2. Don’t routinely hyperventilate, only if necessary CO2. Don’t routinely hyperventilate, only if necessary

for “swollen” brain.for “swollen” brain. Diuretics or Dexamethasone? Diuretics or Dexamethasone?

Usually do give diuretics, particularly mannitol Usually do give diuretics, particularly mannitol Usually don’t give dexamethasone or steroids Usually don’t give dexamethasone or steroids

Early decompressive craniectomy or temporal lobe decompression might Early decompressive craniectomy or temporal lobe decompression might be necessary in dire circumstances. be necessary in dire circumstances.

Fluids. Avoid hypovolemia. Fluids. Avoid hypovolemia. Glucose. Treat hyperglycemia. Glucose. Treat hyperglycemia. Hypothermia was “hot,” but now it’s not. Avoid hyperthermia. Hypothermia was “hot,” but now it’s not. Avoid hyperthermia. IV and Inhaled Anesthetics IV and Inhaled Anesthetics

Ruptured intracranial aneurysm or arteriovenous malformation (AVM) Ruptured intracranial aneurysm or arteriovenous malformation (AVM) Prevent sudden increases or decreases in MAP that predispose the Prevent sudden increases or decreases in MAP that predispose the

aneurysm to ruptureaneurysm to rupture Hyperventilation may depend on Hunt-Hess Grade: Hyperventilation may depend on Hunt-Hess Grade:

Grade 0 – hyperventilation O.K. Grade 0 – hyperventilation O.K. Grades 1-2 – normocarbia or modest hypocarbia (paCO2 = 35) to prevent Grades 1-2 – normocarbia or modest hypocarbia (paCO2 = 35) to prevent

vasospasm vasospasm Grades 3-5 – hyperventilation may be necessary anyway Grades 3-5 – hyperventilation may be necessary anyway

EEG monitoring if barbiturate coma is needed during temporary clipping.EEG monitoring if barbiturate coma is needed during temporary clipping. Moderate induced hypothermia? The results of the completed IHAST Moderate induced hypothermia? The results of the completed IHAST

trial indicate no better outcome with hypothermia (33.5 oC) than trial indicate no better outcome with hypothermia (33.5 oC) than normothermia (36.5 oC) Induced hypotension might be requested if normothermia (36.5 oC) Induced hypotension might be requested if aneurysm ruptures. aneurysm ruptures.

Infratentorial (posterior fossa) surgery Infratentorial (posterior fossa) surgery is unique in that it can be done is unique in that it can be done inin different positions – sitting, lateral decubitus, or prone. different positions – sitting, lateral decubitus, or prone.

Thank youThank you