Advanced | Neuroanesthesia Flashcards
Intravenous administration of mannitol during a craniotomy:
A. Decreases intracranial pressure relative to dosage
B. Hastens excretion of pancuronium
C. Induces metabolic alkalosis
D. Produces a sustained increase in intravascular volume
E. Requires an intact blood-brain barrier to decrease brain water
E. Requires an intact blood-brain barrier to decrease brain water
The most important monitor of CNS function is:
A. Neurologic examination of an awake and responsive patient
B. Evoked Potential of a hemodynamically stable patient
C. EEG of a hemodynamically stable patient
D. EMG of an awake and responsive patient
A. Neurologic examination of an awake and responsive patient
Barash | 9th edit
Which method of evoked potential is MOST sensitive to anesthesia?
A. SSEP
B. MEP
C. VEP (Visual Evoked Potential)
D. BAEP
VAEP
Visual evoked potentials (VEP) are the MOST SENSITIVE to anesthetic technique and are rarely ever us ed.
The evoked potentials in order from least to most sensitive to anesthetic technique are: BAEP < SSEP < MEP< VEP, (SSEP = somatosensory evoked potential, MEP = motor evoked potential).
- How can aneurysms rupture if CSF is lost?Another way to remember: BAEP are Barely affected, SSEP are Somewhat affected, MEP are Mostly affected, and VEP are Very affected.
Which of the following statements concerning brain stem auditory evoked responses is most ACCURATE?
A. They monitor cortical function
B. They are not affected by changes in carbon dioxide tension
C. They are not affected by mild hypothermia (34°C)
D. They are more resistant to anesthetic effects than somatosensory evoked responses
E. They are abolished coincident with flattening of the EEG
D. They are more resistant to anesthetic effects than somatosensory evoked responses
- BAEP is not a measure of cortical function.
Which of the following is the primary function of Somatosensory Evoked Potentials (SSEPs) in intraoperative monitoring?
A) Monitoring the integrity of the motor pathways in the brain
B) Assessing the function of the peripheral nerves, dorsal columns of the spinal cord, and sensory areas of the brain
C) Monitoring the activity of the autonomic nervous system
D) Evaluating the strength of cortical responses to motor stimuli
B) Assessing the function of the peripheral nerves, dorsal columns of the spinal cord, and sensory areas of the brain
Somatosensory Evoked Potentials (SSEPs) are primarily used to monitor the integrity of sensory pathways, including the peripheral nerves, dorsal columns of the spinal cord, brainstem, subcortex, and sensory cortex.
This modality helps ensure that sensory function remains intact during procedures that may involve these areas, such as spine or neurosurgical operations.
The stimuli travel predominantly via the POSTERIOR column/medial lemniscus pathway, which is responsible for sensory processing.
Therefore, option B is the most accurate response
A 6-year-old boy undergoes craniotomy in the supine position for brain tumor during anesthesia with 1.5% isoflurane in oxygen. PetCO2 is 38 mmHg, heart rate is 78 bpm, and blood pressure is 130/80 mmHg. After opening the dura, the surgeon notes that the brain is bulging. Which of the following management options is LEAST likely to significantly decrease brain size?
(A) Decreased isoflurane concentration
(B) Furosemide
(C) Hyperventilation to a PaCO2 of 25 mmHg
(D) Mannitol
(E) Nitroprusside
Nitroprusside
During exposure of the aneurysm, burst suppression on the EEG may be desired to decrease the impending ischemic burden on the brain from temporary occlusion of large cerebral vessels.
If PROPOFOL is to be used to accomplish ‘BURST SUPRESSION’, the dose should be:
A. IV bolus 1 - 2 mg/kg followed by cont inuous infusion of 100 - 150 μg/kg/min
B. IV bolus 0.5 - 1 mg/kg followed by continuous infusion of 50 - 75 μg/kg/min
C. IV bolus of 3 - 5 mg/kg
Burst suppression can be accomplished with propofol administered as a 1- to 2-mg/kg bolus followed by infusion of 100 to 150 μg/kg/min.
During exposure of the aneurysm, although not fully supported by human clinical data, burst suppression on the EEG may be desired to decrease the impending ischemic burden on the brain I from temporary occlusion of large cerebral vessels.
Burst suppression can be accomplished with propofol administered as a 1- to 2-mg/kg bolus followed by infusion of 100 to 150 μg/kg/min. Additional vasopressor may be required during this time to maintain CPP.
Suppose there is a difficulty placing temporary clips during aneurysm clipping, which of the the following agent can MOST likely cause a transient circulatory arrest to allow a safe clip application?
A. Adenosine
B. Nitroprusside
C. NTG
D. Clevidipine
A. Adenosine
Prior to direct clipping of the aneurysmal neck, the surgeon may place one or more temporary clips on parent or feeding arteries to “soften” the neck and make it more amenable to direct clipping while minimizing the chances of rupture.
Alternatively, when temporary clips are anatomically difficult to place, adenosine 0.3 to 0.4 mg/kg may be safely given as a bolus to cause a transient (3- to 5-second) circulatory arrest allowing safe
permanent clip application.
This is the time or phase during clipping of aneurysm where in the brain is at greatest risk of ischemia?
A. Temporary clipping
B. Permanent clipping
C. Both temporary and permanent clipping
Both temporary and permanent clipping
During temporary and permanent clipping, SSEP and MEP monitoring may be performed more frequently as this is the time during which the brain is at greatest ischemic risk.
SSEP’s are elicited in a cyclical, repetitive manner from a peripheral nerve and usually measured at the level
of the subcortex. Stimuli predominantly travel via the posterior column/medial lemniscus pathway in
the CNS. Lower extremity SSEP’s tend to correlate with the integrity of cortex supplied by the ____
A. MCA
B. ACA
C. Basilar A.
D. Vertebral A.
B. ACA
.
Lower extremity SSEPs tend to correlate with the integrity of cortex supplied by the ACA whereas upper extremity SSEPs tend to correlate with the cortex supplied by the MCA distribution.
SSEPs are elicited in a cyclical, repetitive manner from a peripheral nerve (e.g., median, ulnar, posterior tibial) and usually measured at the level of the subcortex (upper cervical spine, inion) and cortex (scalp). Stimuli predominantly t ravel via the posterior column/medial lemniscus pathway in the CNS.
The commonly used definitions
of “significant changes” to the SSEP waveform include a decrease in the
amplitude by 50% or an increase in the latency by 10% although experienced practitioners consider baseline drift and reproducibility and adapt warning criterion to account for these changes.
In terms of grading the aneurysm, a FISHER grade III corresponds to:
A. No subarachnoid blood seen
B. Diffuse vertical layers of blood <1.5 mm thick
C. Localized clot and/or vertical layer of blood ≥1 mm thick
D. Localized clot and/or vertical layer of blood ≥ 0.5 mm thick
E. Intracerebral or intraventricular clot with diffuse or absent subarachnoid hemorrhage
C. Localized clot and/or vertical layer of blood ≥1 mm thick
How can aneurysms rupture in the setting of a reduced or absent CSF?
With loss of CSF volume, there can be an acute drop in ICP —> This can lead to an increase in the transmural gradient and therefore a rupture in the aneurysm.
What is transmural gradient?
Pressure inside (MAP in case of cerebral aneurysm) - Pressure outside (ICP)
- Acute increase in the aneurysm transmural gradient (mean arterial pressure minus intracranial pressure) should be avoided to prevent rupture or rebleeding.
The most likely cause of bilateral fixed and dilated pupils after clipping of a basilar artery aneurysm is:
A. preoperative administration of atropine
B. intraoperative infusion of trimethaphan
C. naloxone antagonism of opioid
D. persistent hypothermia
E. brain stem ischemia
B. intraoperative infusion of trimethaphan
During trimethaphan infusion, cerebral blood flow decreased, although cerebral metabolic rate for oxygen was unchanged due to increased oxygen extraction by the brain.
Trimethaphan also produced a decrease in myocardial blood flow that was in proportion to the decrease in myocardial oxygen requirement as indicated by pressure-rate product.
One hour after induction of anesthesia for a posterior fossa craniotomy using opioid, relaxant, and nitrous oxide, the brain begins to protrude through the dura. The most effective measure to decrease intracranial pressure is to:
(A) administer additional opioid
(B) decrease PaCO2 from 25 to 15 mmHg
(C) drain cerebrospinal fluid
(D) discontinue nitrous oxide
(E) induce hypotension
(C) drain cerebrospinal fluid
A “significant change” to the SSEP waveform is:
A. amplitude decrease by 50%
B. latency increase by 10%
C. amplitude decrease by 10%
D. latency increase by 50%
E. Both A and B are correct
E. Both A and B are correct
The commonly used definitions
of “significant changes” to the SSEP waveform include a decrease in the
amplitude by 50% or an increase in the latency by 10%
This neuromonitoring modality is not a monitor of ischemia but very sensitive to both mechanical and thermal injury:
A. SSEP
B. EMG
C. BAEP
D. VEP
B. EMG
EMG is sensitive to both
mechanical and thermal injury. EMG, unlike SSEPs and MEPs, is not a monitor of ischemia. Needle electrodes are placed in a muscle known to be innervated by a particular nerve root, and if that nerve root is disturbed, EMG activity is recorded from that muscle.
- EMG is particularly sensitive to the effects of muscle relaxants
The most sensitive means of detecting venous air embolism is
(A) precordial Doppler stethoscope
(B) transesophageal echocardiography
(C) end-tidal carbon dioxide measurement
(D) pulmonary artery pressure measurement
(E) central venous pressure measurement
(B) transesophageal echocardiography
Monitoring for VAE in the sitting position may include precordial Doppler ultrasonography, which can detect 0.25 mL of air in the heart.
A more sensitive monitor is transesophageal echocardiography, which is much more cumbersome, invasive, and requires an observer familiar with this technique.
Also, transesophageal echocardiography may not allow for continuous monitoring for air as the device will cease working when probe temperature rises. However, transesophageal echocardiography allows for a quantitative assessment of intracardiac air whereas precordial Doppler sonography is a qualitative monitor for VAE.
Which of the following can be used as a sole criterion for brain death?
(A) Absence of cerebral blood flow
(B) Absence of doll’s eye movements
(C) Fixed, dilated pupils
(D) Isoelectric EEG
(E) Unresponsiveness to all externally applied stimuli
(A) Absence of cerebral blood flow
which of the following VAE treatment is reserved in the setting of severe or unremitting manifestations of VAE?
A. Notifying the surgeon to flood the surgical field
B. Administering 100% oxygen,
C. Aspirating air through a multiorifice central venous catheter
D. Adjusting the OR table position with the head table at the level of the heart
E. Vasopressors
D. Adjusting the OR table position with the head table at the level of the heart
Treatment of VAE includes notifying the surgeon to flood the surgical field, administering 100% oxygen, aspirating air through a multiorifice central venous catheter positioned at the junction of the superior
vena cava and right atrium, and supportive hemodynamic care.
Depending on the degree of hemodynamic perturbation, treatment may include
vasopressors, fluids, inotropes, and adjusting the OR table position so that the head is at the level of the heart. * This final maneuver is saved for severe or unremitting manifestations of VAE as it likely will disrupt the surgical field.
Which of the following is NOT a feature of SIADH?
A. Volume overload
B. Hypernatremia
C. Hyponatremia
B. Hypernatremia
SIADH is common in patients with sellar tumors due to compression of the posterior pituitary and an excess of circulating antidiuretic hormone (ADH).
SIADH may lead to intravascular volume overload and
hyponatremia. Extracellular body water is usually normal, and edema or hypertension is usually not characteristic.
Each of the following statements about the blood supply of the spinal cord is true EXCEPT:
(A) The anterior spinal artery is made up of branches from the vertebral, intercostal, and iliac arteries
(B) The segmental blood supply of the cord depends upon the location of the arteria radicularis magna (Adamkiewicz)
(C) The posterior spinal arteries supply most of the spinal cord
(D) Obstruction of the inferior vena cava increases blood flow through the epidural venous plexus
(E) The spinal cord is supplied by one anterior spinal artery and two posterior spinal arteries
(C) The posterior spinal arteries supply most of the spinal cord
Each of the following is an effect of rapid infusion of mannitol EXCEPT
(A) depletion of electrolytes
(B) impaired platelet adhesiveness
(C) increased intracranial pressure
(D) increased intravascular fluid volume
(E) increased renal blood flow
(B) impaired platelet adhesiveness
Which of the following is NOT a risk factor for developing cerebral aneurysm?
A. Age over 40 years
B. Male sex
C. cigarette smoking
D. Systemic hypertension
E. Connective tissue disorders
B. Male sex
These are the risks for developing aneurysm and the likelihood of rupture:
age over 40 years
female sex
cigarette smoking
systemic hypertension, and connective tissue disorders
Cerebral blood flow is decreased by:
(A) chronic respiratory acidosis
(B) hypoxia
(C) hypoglycemia
(D) polycythemia
(E) the postictal state
(D) polycythemia
A 55-year-old man has quadriplegia after undergoing suboccipital craniotomy in the sitting position for treatment of acoustic neuroma. Which of the following is the most likely cause?
(A) Air embolism with the presence of a probe-patent foramen ovale
(B) Compression of the cervical cord related to neck flexion
(C) Jugular venous obstruction
(D) Postoperative tension pneumocephalus
(E) Sustained elevation of cerebral perfusion pressure
(B) Compression of the cervical cord related to neck flexion
Massive venous air embolism occurs in a patient who is undergoing craniotomy in the sitting position with nitrous oxide, oxygen, fentanyl anesthesia. Which of the following changes in end-tidal (ET) concentrations of carbon dioxide, nitrogen, and nitrous oxide are most likely in this patient? (ETCO2, ETN2, ETN2O)
(A) Increased, increased, decreased
(B) Decreased, decreased, increased
(C) Decreased, decreased, decreased
(D) Decreased, increased, decreased
(E) Increased, decreased, decreased
(D) Decreased, increased, decreased
A 35 year old male is undergoing neurosurgical procedures in a sitting position. His blood pressure should be corrected to the level of the:
A. External auditory meatus
B. Internal auditory meatus
C. In close proximity with the sagittal sinus
D. 0.5 mm lateral to the sagittal sinus
A. External auditory meatus
This is the target CPP value in the first 48 to 72 hours after TBI in adults:
A. 60 - 70 mmHg
B. 25 -50 mmHg
C. 10 - 20 mmHg
D. 70 -100 mmHg
A. 60 - 70 mmHg
CPP (CPP = MAP − ICP) should be supported to a target range of 60 to 70 mm Hg in the first 48 to 72 hours after TBI in adults.
Which of the following branch of circle of willis is the most common site of aneurysm?
A. ACA
B. MCA
C. PCOM A.
D. Basilar A.
A. ACA
Ruptured aneurysms are the
most common cause of spontaneous SAH, accounting for 80% of nontraumatic SAH.
Aneurysms are thought to arise from turbulent blood flow
at arterial branching points, causing “sac-like” or “fusiform” dilatations.
Cerebral aneurysms most commonly occur at the anterior communicating arteries (40%), PCOMs (25%), and MCA (25%), with only 10% arising from the vertebrobasilar system.
Which of the following can be utilized to prognosticate the aneurysm based on clinical presentation?
A. The Hunt and Hess Grading Scale
B. World Federation of Neurological Surgeons Grading Scale
C. Fisher Grade System
D. GCS
A. The Hunt and Hess Grading Scale
TRUE or FALSE
Most AVM’s have a high risk of rupture even with an acute rise of BP(as with laryngoscopy).
FALSE
Most AVMs are high-flow and low resistance shunts, the incidence of sudden rupture with acute rises in
systemic blood pressure (as with direct laryngoscopy) is low unless there is an accompanying aneurysm.
A type of autoregulatory inhibition caused by the AVM affecting the surrounding “normal” brain, in which previously normal cerebral vessels are maximally vasodilated due to longstanding “steal” caused by the AVM:
A. Coronary steal
B. Cytotoxic Vasospasm
C. normal perfusion pressure
breakthrough
D. Occlusive hyperemia
C. normal perfusion pressure
breakthrough
The phenomenon of normal perfusion pressure breakthrough (NPPB), is controversial in terms of its mechanism, but clinically relevant to the anesthesiologist. NPPB is thought to be a type of autoregulatory inhibition caused by the AVM affecting the surrounding
“normal” brain, in which previously normal cerebral vessels are maximally vasodilated due to longstanding “steal” caused by the AVM.
After the AVM has been resected, these “vasoparalyzed” vessels are unable to vasoconstrict, leading to cerebral hyperemia, cerebral edema, headache, and possibly increased risk for postoperative bleeding.
A neurologically intact 48-year-old woman is scheduled for removal of a parietal lobe arteriovenous malformation. The relative risk for complete resection is to be determined by a test occlusion of the feeding artery. Which of the following intraoperative monitoring techniques is most appropriate for this test?
(A) Brain stem auditory evoked potentials
(B) Cerebral blood flow using radioactive xenon
(C) EEG
(D) Evoked potentials elicited by stimulating the posterior tibial nerve
(E) Transcranial Doppler
(D) Evoked potentials elicited by stimulating the posterior tibial nerve
Which of the following interventions is most effective in preventing neurologic injury resulting from global cerebral ischemia?
(A) Induction of barbiturate coma prior to ischemia
(B) Maintenance of serum glucose concentration greater than 200 mg/dl prior to ischemia
(C) Induction of hypothermia to a core temperature of 15 degrees C prior to ischemia
(D) Maintenance of PaCO2 less than 25 mmHg following ischemia
(E) Prevention of systemic hypertension following ischemia
(C) Induction of hypothermia to a core temperature of 15 degrees C prior to ischemia
The following changes occur during posterior cervical fusion in the prone position under halothane and nitrous oxide anesthesia with mechanical ventilation: HR 78 to 84 with frequent PVCs; BP 110/70 to 90/50; EtCO2 4.5% to 2.0%; EtN2 0.12% to 4%. The most appropriate next step is to:
(A) administer lidocaine intravenously
(B) decrease ventilatory rate
(C) discontinue halothane
(D) lower the patient’s head
(E) inspect the ventilator bellows
(D) lower the patient’s head
Treatment of VAE includes notifying the surgeon to flood the surgical field, administering 100% oxygen, aspirating air through a multiorifice central venous catheter positioned at the junction of the superior
vena cava and right atrium, and supportive hemodynamic care.
Depending on the degree of hemodynamic perturbation, treatment may include
vasopressors, fluids, inotropes, and adjusting the OR table position so that the head is at the level of the heart. * This final maneuver is saved for severe or unremitting manifestations of VAE as it likely will disrupt the surgical field.
Occlusion of ___ percent is indicative of carotid plaque removal.
A. 70%
B. 30%
C. 45%
A. 70%
Surgery to remove carotid plaque that may be causing symptomatic cerebral ischemia is generally indicated when the plaque burden is over 70% occlusive in the ICA.
One of the preoperative concern in pituitary tumor is the hormonal disturbances when the pituitary
lesion expands and compresses the pituitary tissue. Generally, the
normal glandular function is compromised. Which of the following hormone is typically lost first?
A. Gonadotropins
B. Growth hormone
C. ACTH
D. Thyroid-stimulating
hormone
A. Gonadotropins
Hormonal function is lost in the following sequence: first, gonadotropins; second, growth hormone; third, ACTH; and fourth
and last, thyroid-stimulating
hormone. A decrease in
ACTH secretion results in a hypo-adrenal state. Attention to this is critical because an Addisonian crisis can ensue, especially under the stress of surgery.
Pituitary hormones are lost in this sequence:
Gonadotropins > Growth hormone > ACTH > Thyroid-stimulating
hormone
Treatment of perioperative SIADH
involves the following except:
A. Water restriction
B. Demeclocycline
C. Desmopressin
D. Anti-hypertensive
D. Anti-hypertensive
Treatment of perioperative SIADH
involves water restriction (to the extent that it is safe to do so), treating the underlying cause, demeclocycline (a tetracycline antibiotic that inhibits ADH
action in the renal tubules), and desmopressin for persistent or severe cases.
A patient suddenly makes a respiratory effort during craniotomy for clipping of a cerebral aneurysm in a 15-degree head-up position with controlled ventilation. The most likely cause is
(A) air embolism
(B) cerebral hypoxia
(C) direct stimulation of the respiratory center
(D) intraventricular hemorrhage
(E) stimulation of the motor cortex
(A) air embolism
Which of the following best describes the relationship between cerebral perfusion pressure and cerebral blood flow in a patient with untreated chronic hypertension?
(A) It is constant at mean blood pressures between 50 and 150 mmHg
(B) It is linear for all blood pressures
(C) Flow versus pressure curve is hyperbolic
(D) Flow versus pressure curve is shifted to the right
(E) Flow versus pressure curve is shifted to the left
(D) Flow versus pressure curve is shifted to the right
In patients with blunt head trauma, cerebral perfusion pressure is determined by the gradient between:
(A) diastolic pressure and central venous pressure
(B) intracranial pressure and central venous pressure
(C) mean arterial pressure and central venous pressure
(D) mean arterial pressure and intracranial pressure
(E) systolic pressure and intracranial pressure
(D) mean arterial pressure and intracranial pressure
Which of the following statements concerning brain stem auditory evoked responses is true?
(A) They monitor cortical function
(B) They are not affected by changes in PaCO2
(C) They are not affected by mild hypothermia (34°C)
(D) They are more resistant to anesthetic effects than
somatosensory evoked responses
(E) They are abolished coincident with flattening of the EEG
(D) They are more resistant to anesthetic effects than
somatosensory evoked responses
A 32-year-old woman is anesthetized for suboccipital craniotomy. During positioning, the capnograph shows an abrupt decrease in the slope of the expiratory upstroke. Which of the following is the most likely cause?
(A) Air embolism
(B) Incompetent expiratory valve
(C) Incomplete neuromuscular block
(D) Kinked endotracheal tube
(E) Tracheal extubation
(D) Kinked endotracheal tube
A patient who is receiving ventilatory support after coronary artery bypass grafting has a PaO2 of 132 mmHg, a PaCO2 of 19 mmHg, and a pH of 7.57.
Which of the following is most likely to result from this level of hypocarbia?
(A) Decreased airway resistance
(B) Increased myocardial contractility
(C) Hyperkalemia
(D) Shortened QT interval
(E) Cerebral ischemia
(E) Cerebral ischemia
TRUE or FALSE
In contrast with carotid stenting, carotid endarterectomy poses very lower incidence of post-operative stroke.
TRUE
The most significant advantage of carotid endarterectomy over
stenting is that it has an overall lower incidence of postoperative stroke (particularly in older patients) and restenosis, whereas potential disadvantages of this surgery include the need for a general or regional anesthetic technique, a possible increased risk for cardiac events, and a higher incidence of cranial nerve dysfunction.
However, carotid artery
stenting may be accomplished with very minimal sedation and carries a
lower incidence of cranial nerve injury, although it has been associated with a higher risk of restenosis and stroke in the postprocedural period
Which has a higher incidence of intra-operative cranial nerve injury?
A. Carotid endarterectomy
B. Carotid stenting
B. Carotid stenting
A 55 year old female is undergoing “AWAKE” carotid surgery with low-dose analgesia and sedation using remifentanil or propofol. Intraoperatively, the patient suddenly becomes agitated and unresponsive. As the anesthesiology attending, you assumed this to be cerebral ischemia. Which of the following is the BEST option in the management?
A. Increasing systemic blood pressure up to 20%
B. Decreasing the systemic blood pressure by 20%
C. Check the blood glucose
D. Recalibrate the EEG monitor
If the patient becomes agitated,
confused, or unresponsive following carotid occlusion, the anesthesiologist should assume that cerebral ischemia has ensued and assure adequate
perfusion and oxygenation by increasing systemic blood pressure up to 20% greater than preoperative values.
Barash | 9th edit
Asleep” carotid surgery employs general endotracheal anesthesia and frequent monitoring for cerebral ischemia. A carotid stump pressure is a measure in the internal carotid artery. What is the desirable pressure that reflects adequate collateral blood flow via the circle of willis?
A. 50 mmHg or higher
B. 100 mmHg or higher
C. 25 mmHg or higher
D. None of the above
A. 50 mmHg or higher
Carotid stump pressure is the pressure measured in the internal carotid artery distal to the cross-clamp and is thought to reflect adequate collateral blood flow via the circle of Willis.
- A stump pressure greater than 50 mmHg is desirable.
During carotid surgery, Eucapnia has an advantage in order to maintain CBF and prevent “steal phenomenon”. Which of the following can potentially lead to this phenomenon?
A. Hypoventilation and hypercapnia
B. Hypoventilation and hypercapnia
C. Hyperventilation and hypocapnia
D. Hyperventilation and hyperthermia
B. Hypoventilation and hypercapnia
General anesthesia provides the advantages of a motionless patient, the ability to ensure eucapnia, and control of the airway at all times.
Eucapnia is preferred, as hyperventilation will cause cerebral vasoconstriction and decreased CBF, whereas hypoventilation and hypercapnia may lead to a
“steal” phenomenon from watershed areas of cerebral perfusion.
Hyperventilation = cerebral vasoconstriction and DECREASE CBF.
Hypoventilation = cerebral vasodilation and INCREASE CBF
Cross-clamping occlusion of the common carotid artery may possibly elicit baroreceptor reflex such as bradycardia and hypotension. This can be prevented by:
A. Infiltration of lidocaine at the carotid sinus
B. Prophylactic Norepinephrine to prevent hypotension
C. Epinephrine flush
D. Deep cervical plexus block
A. Infiltration of lidocaine at the carotid sinus
Upon cross-clamp occlusion of the common carotid artery, blood pressure should be augmented to improve collateral flow from the contralateral side, often
requiring a vasopressor. During manipulation of the carotid baroreceptor, bradycardia and possibly hypotension are not uncommon, and the surgeon
may infiltrate the carotid sinus with lidocaine to prevent this response.
Barash | 9th edit
Anesthetic technique to consider when doing carotid surgery:
General Anesthesia:
Ensures a motionless patient, eucapnia, and airway control.
Eucapnia prevents cerebral vasoconstriction (from hyperventilation) and “steal” phenomenon (from hypoventilation/hypercapnia).
Invasive Arterial Blood Pressure Monitoring:
Preferred to monitor blood pressure, as operative morbidity is often neurologic and mortality is usually cardiac.
Patients are often chronically hypertensive preoperatively and may have cardiovascular disease.
Maintain blood pressure at baseline levels, especially before cross-clamping.
Regional anesthesia may maintain baseline blood pressure; general anesthesia may require pharmacologic manipulation.
Cross-Clamping of Carotid Artery:
Typically occurs above and below the plaque (common carotid artery below, ICA above).
Heparinization is often done prior to cross-clamping.
Post-cross-clamp: Blood pressure may need augmentation for improved collateral flow (using vasopressors).
Carotid Baroreceptor Manipulation:
Bradycardia and hypotension can occur; lidocaine infiltration may be used to prevent this.
After restoring flow: Hypertension may persist due to surgical denervation of the carotid baroreceptor.
Cerebral vessels distal to stenosis may not autoregulate, leading to risks of cerebral edema and hemorrhage.
Postoperative Complications:
Monitor closely for neurologic compromise, which could indicate cerebral emboli or ICA thrombosis.
Be alert for postoperative neck hematoma, which could compromise the airway.
Immediate intubation and surgical exploration may be needed.
Consider surgical incision to decompress the airway in case of expanding neck hematoma.
A 19 year old male came in with a GCS of 8. He sustained a head injury secondary to vehicular accident. As the anesthesiology resident on duty, you were called in for emergency endotracheal intubation prior to emergency decompressive craniectomy. Which of the following is NOT an indication for decompressive craniectomy?
A. midline shift of less than 5mm
B. subdural hematoma
C. Depressed skull fracture
D. Dural breech
Operative management, such as decompressive
craniectomy, is normally indicated for depressed skull fractures, dural
breech, midline shift more than 5 mm, basal cistern compression, refractory
ICP elevation, and acutely expanding intracranial hemorrhage, including
subdural and epidural hematomas
An otherwise healthy 16-year-old girl is undergoing posterior spinal fusion for thoracolumbar scoliosis. During the procedure, the most likely cause of a marked decrease in the amplitude of the somatosensory evoked potentials after stimulation of the posterior tibial nerve is:
(A) administration of fentanyl 30 mg/kg for induction
(B) administration of isoflurane 1.3 MAC for maintenance
(C) administration of vecuronium 0.15 mg/kg
(D) a decrease in body temperature from 37 to 35°C
(E) a decrease in cerebrospinal fluid pressure
(B) administration of isoflurane 1.3 MAC for maintenance
Muscle relaxants may be helpful as they tend to remove artifact caused by spontaneous EMG activity. SSEPs are commonly used during spine surgery, especially when posterolateral sensory elements are at risk of ischemia from
surgical distraction.
A18 year old male needs brain relaxation intraoperatively. Preoperatively, you were asked which medication/agent can be used to achieve BURST SUPRESSION. This can be achieved with the following EXCEPT:
A. Desflurane >1.5 MAC
B. Isoflurane >1.5 MAC
C. Etomidate
D. N2O
E. Barbiturates
D. N2O
Which of the following statements concerning postspinal headache is true?
(A) Cerebrospinal fluid leukocytosis occurs
(B) Intravenous caffeine therapy is more effective than epidural blood patch
(C) The incidence decreases with age
(D) The incidence is higher in males than in females of all ages
(E) The incidence is the same after single or multiple dural punctures
(C) The incidence decreases with age
Which of the following statements concerning barbiturate protection from cerebral ischemia is TRUE?
(A) It may be achieved with dosages low enough to avoid cardiovascular effects
(B) It is linearly dose-related
(C) It improves neurologic outcome following cardiac arrest
(D) It is most useful in patients with focal ischemia
(E) It is unrelated to EEG activity
(D) It is most useful in patients with focal ischemia
A 62-year-old man is in the intensive care unit after successful craniotomy for excision of a meningioma. Blood volume is normal; laboratory studies show serum sodium concentration of 120 mEq/L, serum osmolality of 260 mOsm/L, urine sodium concentration of 50 mEq/L, and urine osmolality of 820 mOsm/L. Which of the following is the most likely explanation?
(A) Fluid overload with 5% dextrose in water
(B) Inappropriate secretion of antidiuretic hormone
(C) Increased free water clearance
(D) Nephrogenic diabetes insipidus
(E) Neurogenic diabetes insipidus
(B) Inappropriate secretion of antidiuretic hormone
Anesthetic concerns for pituitary surgery include systemic manifestations of any associated endocrinopathy, electrolyte and fluid disturbances caused by
endocrine disease, SIADH, or DI, and inadvertent surgical trespass into the cavernous sinus or internal carotid artery.
SIADH is common in patients with sellar tumors due to compression of the posterior pituitary and an excess of circulating antidiuretic hormone (ADH).
SIADH may lead to intravascular volume overload and hyponatremia. Extracellular body water is usually normal, and edema or hypertension is usually not characteristic.
In contrast, Diabetes insipidus very rarely arises intraoperatively;
it usually occurs 12 to 48 hours postoperatively. The clinical picture is one of polyuria in association with a rising serum osmolality. The diagnosis is made by comparison of
the osmolality of urine and serum. Hypo-osmolar urine in
the face of an elevated and rising serum osmolality strongly
supports the diagnosis.
The most important factor regulating blood flow to ischemic cerebral tissue is
(A) systolic blood pressure
(B) PaO2
(C) cerebral perfusion pressure
(D) PaCO2
(E) cerebral oxygen consumption
(C) cerebral perfusion pressure
A 50 year old male is admitted at the neurocritical area for a possible vasospasm after he sustained SAH. The critical role of which of the following drugs best facilitates management of cerebral vasospasm after subarachnoid hemorrhage?
(A) Nifedipine
(B) Nimodipine
(C) Nitroglycerin
(D) Nitroprusside
(E) Thiopental
(B) Nimodipine
Cerebral vasospasm rarely occurs within 72 hours of rupture. Surgical or endovascular treatment of ruptured aneurysms is generally undertaken within the first 48 hours after presentation of SAH, to minimize the risk of rebleeding but prior to increased risk for cerebral vasospasm.
- Nimodipine is the only intervention that decreases risk for cerebral vasospasm.
MOA: During the depolarization of smooth muscle cells of blood vessels, there is an influx of calcium ions. The primary function of nimodipine is to block voltage-gated L-type calcium channels and keep them in their inactive conformation, preventing vasoconstriction.
- Nimodipine preferentially acts on cerebral blood vessels because it is lipophilic and can cross the blood-brain barrier. Proposed mechanisms leading to a beneficial effect include decreased angiographic vasospasm, increased fibrinolytic activity, and enhanced neuroprotection.
Which of the following detects the smallest volume of venous air embolization?
(A) Changing the precordial Doppler ultrasound signal
(B) Decreasing PetC02
(C) Decreasing Sp02
(D) Increasing central venous pressure
(E) Increasing pulmonary artery pressure
(A) Changing the precordial Doppler ultrasound signal
ABA ITE question
A 50-year-old patient is undergoing craniotomy for clipping of a cerebral aneurysm with isoflurane, nitrous oxide, and fentanyl anesthesia. At the time of aneurysm exposure, the EEG shows burst suppression. Which of the following is the most likely cause?
(A) Cerebral ischemia
(B) Cerebral vasospasm
(C) Fentanyl effect
(D) Isoflurane effect
(E) Petit mal seizure activity
(D) Isoflurane effect
At 1.5 MAC All the inhaled anesthetics EXCEPT N2O can induce BURST SUPPRESSION.
A 4-month-old child undergoing a craniectomy for craniosynostosis is anesthetized with nitrous oxide and halothane. Suddenly the systolic blood pressure decreases from 75 to 30 mmHg, and the PetCO2 decreases from 35 to 6 mmHg. Which of the following maneuvers is LEAST likely to have a beneficial effect?
(A) Administration of a fluid bolus
(B) Administration of a vasopressor
(C) Application of positive end-expiratory pressure
(D) Discontinuation of nitrous oxide
(E) Flooding the surgical wound with saline solution
(C) Application of positive end-expiratory pressure
Rationale to follow…
In a patient who is to undergo clipping of a cerebral aneurysm, an advantage of isoflurane over nitroprusside for induction of hypotension is:
(A) better maintenance of cardiac output
(B) better maintenance of cerebral blood flow
(C) greater decrease in cerebral oxygen consumption
(D) greater decrease in afterload
(E) more rapid titration of systemic blood pressure
(C) greater decrease in cerebral oxygen consumption
A 35-year-old woman with a grade III subarachnoid hemorrhage is undergoing clipping of a middle cerebral artery aneurysm 48 hours after initial hemorrhage. Which of the following drugs used to induce hypotension is LEAST likely to affect intracranial pressure?
(A) Esmolol
(B) Hydralazine
(C) Isoflurane
(D) Nitroglycerin
(E) Sodium nitroprusside
(A) Esmolol
Which of the following best reflects findings of inadequate cerebral perfusion during carotid cross clamping?
A. Decreased frequency on EEG
B. Increased latency of brain stem auditory evoked potentials
C. Increased spectral edge frequency
D. Jugular bulb oxygen tension of 27 mmHg
E. Stump pressure of 50 mmHg
A. Decreased frequency on EEG
a
tients with SAH often develop m
ny
a
associa
ted ch
a
nges, including
n
a
elev
a
ted ICP, rightw
ard shift in the lower limits of the
a
utoregula
tory curve,
v
asosp
asm, hypovolemia
,
nd hypon
a
a
tremia.
