Chapter 8 - Neurosurgery and Invasive Neuroradiology Flashcards
What is the CBF in infants and children?
90 to 100 ml/100 g/min
What is the CBF in adults?
50 to 60 ml/100 g/min
The CBF varies directly with changes in PaCO2 between what ranges?
20 to 80 mmHg
The CBF changes aproximately ___% per each mmHg of change in PaCO2?
4% change in CBF
for
every mmHg change in PaCO2
Vasoconstriction in normal reactive cerebral vessels in areas that have lost autoregulation will reduce the blood flow?
F
Vasodilate
Termed: Intracerebral Steal
- AVMs
- Vascular tumors
- Areas of infection or trauma
Crebrovascular autoregulation operates over a wide range of mean arterial pressures as low as ___ to ___ mmHg in the supine infant?
As low as
20 to 60 mmHg
in the supine infant
- 50 to 150 mmHg in adults
T/F
Hyperventilation is a way to decrease cerebral blood volume and is generally reserved for acute in ICP
T
What is inverse intracranial steal?
Vasoconstriction
Increases blood flow into areas that lost autoregulations
What are the 3 fixed consituents of the intracranial contents?
Blood
Brain tissue
CSF
T/F
All inhalational agents decrease CBF and reduce the ICP because of their vasodilatory effects
F
All inhalationals increase CBF
May increase ICP
**Unless accompanied by mild hyperventilation
(PaCO2 ~ 30 to 35 mmHg)
What is the order that the volatile anesthetics follow from greatest to least and their effect on the CBF?
Des > Hal > Iso > Sevo
What are the three volatile agents that reduce CMRO2?
Halo, Iso, Sevo
- Iso** and **Sevo may provide cerebral protection
against
Hypoxia & Ischemia
What is the ideal induction agent in neurosurgery?
Why?
Thiopental
Reduces ICP
T/F
Thiopental reduces ICP, therefore stimulation from laryngoscopy and intubation is not an issue.
F
Thiopental DOES NOT prevent
increase in BF and ICP
during laryngoscopy and intubation
Administer:
- Lidocaine 1 to 1.5 mg/kg
and
- Fentanyl 2 to 5 mcg/kg
What induction agent reduces CBF, CMRO2 and preserves autoregulation?
Propofol
T/F
Induction doses of Propofol 3 mg/kg may cause mild hypotension but may also MORE effectively blunt the CV response to laryngoscopy and intubation.
T
Which opioid has been demonstrated to increase CSF pressure in children with crebral tumors?
Alfentanil
Nondepolarizing muscle relaxants have no direct effect on CBF, except?
Atracurium
Vasodilation from histamine release
What occurs with the administration of succinylcholine to children with cerebral trauma and other CNS diseases?
Hyperkalemia
T/F
Calcium channel blockers impair autoregulation and may increase CBF and ICP
T
- Sodium Nitroprusside
- Nitroglycerine
- Adenosine
- Calcium Channel Blockers
All impair cerebral autoregulation and may increase CBF and ICP
What med may decrease focal cerebral edema in response to surgical trauma of brain tissue?
Dexamethasone
0.15 mg/kg IV
MAX of 8 mg
T/F
Ketamine increases neuronal function
T
Ketamine increases neuronal function
and
increases CBF
T/F
Thippental Decreases neuronal function
T
Thipental decreases neuronal function
and
decreases CBF
T/F
SSEP monitoring is attenuated by inhalational anesthetics
T
T/F
Nitrous oxide
Propofol
Opioids
&
Muscle relaxants
have litlle effect on SSEPs?
T
What has more sensitivity to the inhalational anesthetics, SSEPs or MEPs?
MEPs
Motor Evoked Potentials
During MEPs, the inhalational agents are limited to what MAC value?
Limited to 0.5 MAC
What inhalational agent is avoided wjen MEPs is used?
Nitrous oxide
T/F
During MEPs, muscle relaxants are completely avoided
T/F
Propofol
Alpha - 2 Agonist
Benzos and opioids DO NOT significantly compromise
MEPs.
T
A PaCO2 of what range is preferred during controlled ventilation?
PaCO2 of 30 to 35 mmHg
