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ASHRAF EL-SAYED EL-AGAMYASHRAF EL-SAYED EL-AGAMYMD AnesthesiaMD Anesthesia
Faculty of MedicineFaculty of MedicineAin Shams UniversityAin Shams University
Definition: It is the removal of athermatous plaques from the
vessel lumen. If the remaining intima is too thin, the vessel is closed with a vein or a synthetic patch.
Pathology: Atherosclerotic carotid artery disease is part of
atherosclerosis which affects many arteries. It results in decrease blood flow up to complete obstruction of the carotid artery due to embolism, hemorrhage or thromboembolism.
In case of complete obstruction cerebral blood flow continues through collaterals from the opposite carotid system, vertebrobasilar system or the external carotid vessels.
Definition: It is the removal of athermatous plaques from the
vessel lumen. If the remaining intima is too thin, the vessel is closed with a vein or a synthetic patch.
Pathology: Atherosclerotic carotid artery disease is part of
atherosclerosis which affects many arteries. It results in decrease blood flow up to complete obstruction of the carotid artery due to embolism, hemorrhage or thromboembolism.
In case of complete obstruction cerebral blood flow continues through collaterals from the opposite carotid system, vertebrobasilar system or the external carotid vessels.
Clinical picture:
1. Cerebral stroke.
2. Transient ischemic attacks (TIAs.
3. Chronic cerebral ischemia.
4. Asymptomatic carotid bruit.
Clinical picture:
1. Cerebral stroke.
2. Transient ischemic attacks (TIAs.
3. Chronic cerebral ischemia.
4. Asymptomatic carotid bruit.
Indications for surgical
intervention:
1. Persistent unstable neurological status
despite anticoagulation.
2. Repeated TIAs lasting more than 1
hour.
3. Severe stenosis > 70% (even without
symptoms).
Indications for surgical
intervention:
1. Persistent unstable neurological status
despite anticoagulation.
2. Repeated TIAs lasting more than 1
hour.
3. Severe stenosis > 70% (even without
symptoms).
Anesthetic management: Preoperative management: 1- Preoperative assessment of clinical picture of
carotid artery disease: Assess the patient's airway and ventilation with the
patients toleration of neck motion without evidence of cerebral ischemia.
Detection of preoperative risk factors : Impaired consciousness. Poor collaterals. Ipsilateral ischemic lesion in CT. Left sided procedures. Endorterectomy done in conjunction with
coronary artery by pass graft surgery.
Anesthetic management: Preoperative management: 1- Preoperative assessment of clinical picture of
carotid artery disease: Assess the patient's airway and ventilation with the
patients toleration of neck motion without evidence of cerebral ischemia.
Detection of preoperative risk factors : Impaired consciousness. Poor collaterals. Ipsilateral ischemic lesion in CT. Left sided procedures. Endorterectomy done in conjunction with
coronary artery by pass graft surgery.
2- Preoperative assessment of other manifestations
of generalized atherosclerosis.
3- Preoperative assessment of other coexisting
diseases:
If the patient has both atheromatous plaque in the
carotid artery and occlusion of coronary vessels,
carotid endortrectomy is to be done first then
coronary artery bypass graft surgery.
4- Preoperative drug therapy.
2- Preoperative assessment of other manifestations
of generalized atherosclerosis.
3- Preoperative assessment of other coexisting
diseases:
If the patient has both atheromatous plaque in the
carotid artery and occlusion of coronary vessels,
carotid endortrectomy is to be done first then
coronary artery bypass graft surgery.
4- Preoperative drug therapy.
5- Preoperative investigations: Standard investigations (CBC, renal
function tests, liver function tests, ECG).
Cerebral angiography.
Coagulation profile.
Transcranial Doppler.
Other investigations of associated diseases e.g., echocardiography if myocardial ischemia.
6- Premedications.
5- Preoperative investigations: Standard investigations (CBC, renal
function tests, liver function tests, ECG).
Cerebral angiography.
Coagulation profile.
Transcranial Doppler.
Other investigations of associated diseases e.g., echocardiography if myocardial ischemia.
6- Premedications.
Intraoperative management: The major anesthetic problems are: Cerebral ischemia: So avoid cerebral
hypoperfusion.
Myocardial ischemia: So, make balance between O2 supply and demand.
Monitoring: Standard (ECG, pulse oximeter, non invasive blood
pressure, et Co2).
Urine output. Temperature monitoring. Invasive blood pressure, CVP transesophageal echo. Arterial blood gases.
Intraoperative management: The major anesthetic problems are: Cerebral ischemia: So avoid cerebral
hypoperfusion.
Myocardial ischemia: So, make balance between O2 supply and demand.
Monitoring: Standard (ECG, pulse oximeter, non invasive blood
pressure, et Co2).
Urine output. Temperature monitoring. Invasive blood pressure, CVP transesophageal echo. Arterial blood gases.
Monitoring of cerebral perfusion:
(Done at early stage before clamping)
Monitoring of cerebral perfusion:
(Done at early stage before clamping)
a-General anesthesia none of the methods are reliable.
a-General anesthesia none of the methods are reliable.
b- Local anesthesia - It is the most reliable
and sensitive method.- Assess conscious
level, speech and contra lateral hand grip after clamping.
b- Local anesthesia - It is the most reliable
and sensitive method.- Assess conscious
level, speech and contra lateral hand grip after clamping.
1- Jugular venous oxygen saturation:
Sao2: Arterial O2 saturation
CBF: Cerebral blood flow.
Svo2: jugular venous O2 saturation
If decrease in Svo2 indicates decrease in CBF or increased cerebral metabolic rate.
It is unreliable, as it monitor global rather than regional CBF.
1- Jugular venous oxygen saturation:
Sao2: Arterial O2 saturation
CBF: Cerebral blood flow.
Svo2: jugular venous O2 saturation
If decrease in Svo2 indicates decrease in CBF or increased cerebral metabolic rate.
It is unreliable, as it monitor global rather than regional CBF.
2Svo2Sao2Oofratemetaboliccerebral
CBF
2-Internal carotid distal stump pressure (occlusion pressure):
It measures the pressure in the internal carotid artery distal to the cross clamp.
It reflects the pressure transmitted through collaterals, it should be > 25-30 mmHg.
It is unreliable, it doesn't change consistently with changes in ECG or regional cerebral blood flow.
2-Internal carotid distal stump pressure (occlusion pressure):
It measures the pressure in the internal carotid artery distal to the cross clamp.
It reflects the pressure transmitted through collaterals, it should be > 25-30 mmHg.
It is unreliable, it doesn't change consistently with changes in ECG or regional cerebral blood flow.
3- Measurement of cerebral blood flow:
a- Global CBF (for research only): Normally = 50 ml/100gm/min.
If >24 ml/100gm/min adequate.
< 18 ml/100gm/min inadequate.
b- Regional CBF:
1. Intracarotid injection of radioactive xenon then scintillation detection (for research only).
2. Transcranial Doppler. It measure blood flow velocity in the major vessels at the base of the brain via temporal bone.
3- Measurement of cerebral blood flow:
a- Global CBF (for research only): Normally = 50 ml/100gm/min.
If >24 ml/100gm/min adequate.
< 18 ml/100gm/min inadequate.
b- Regional CBF:
1. Intracarotid injection of radioactive xenon then scintillation detection (for research only).
2. Transcranial Doppler. It measure blood flow velocity in the major vessels at the base of the brain via temporal bone.
4- EEG (processed or unprocessed):
In can assess the use and importance of shunt and the adequacy of collaterals.
It is unreliable as the signs of deep anaesthesia are like of cerebral ischemia.
5- Somatosensory evoked potential (SSEPs):
Gives idea about areas of brain at risk of infarction.
They are unreliable because they are not sensitive or specific.
4- EEG (processed or unprocessed):
In can assess the use and importance of shunt and the adequacy of collaterals.
It is unreliable as the signs of deep anaesthesia are like of cerebral ischemia.
5- Somatosensory evoked potential (SSEPs):
Gives idea about areas of brain at risk of infarction.
They are unreliable because they are not sensitive or specific.
6- Transconjunctional O2
tension:
Unreliable as there is no relation
between transconjuctional O2 tension
and regional CBF.
7- Cerebral oximetry:
To assess changes in cerebral blood
flow by measuring regional cerebral
oxygenation.
6- Transconjunctional O2
tension:
Unreliable as there is no relation
between transconjuctional O2 tension
and regional CBF.
7- Cerebral oximetry:
To assess changes in cerebral blood
flow by measuring regional cerebral
oxygenation.
Choice of anesthesia:
A- Regional anesthesia: It is of choice, by:
1. Superficial and deep cervical plexus block.
2. Cervical epidural anesthesia.
3. Local infiltration.
To provide sensory blockade of C2-C4 dermatomes
Advantages: 1. Repeated neurological assessment in awake
patient.
2. Stable BP so decreases the incidence of myocardial infarction perioperatively.
Choice of anesthesia:
A- Regional anesthesia: It is of choice, by:
1. Superficial and deep cervical plexus block.
2. Cervical epidural anesthesia.
3. Local infiltration.
To provide sensory blockade of C2-C4 dermatomes
Advantages: 1. Repeated neurological assessment in awake
patient.
2. Stable BP so decreases the incidence of myocardial infarction perioperatively.
B- General anesthesia:
Advantages:
1. Patient to be quiet for long time surgery.
2. Early control of respiration.
3. Allows brain protective measures to be taken.
4. Avoid excessive neck palpation (which occurs during local anesthesia).
B- General anesthesia:
Advantages:
1. Patient to be quiet for long time surgery.
2. Early control of respiration.
3. Allows brain protective measures to be taken.
4. Avoid excessive neck palpation (which occurs during local anesthesia).
Induction:
Smooth induction after preoxygenation.
Maintenance:
O2: N2O 50%: 50%.
Volatile agents: isoflurane, sevoflurane. Or desflurane are of choice.
Normocarbia is preferred before repair of carotid stenosis.
Induction:
Smooth induction after preoxygenation.
Maintenance:
O2: N2O 50%: 50%.
Volatile agents: isoflurane, sevoflurane. Or desflurane are of choice.
Normocarbia is preferred before repair of carotid stenosis.
Intraoperative problems:
1- Brain protection measures:
(During the period of carotid clamping).
A- Measures to increase CBF:
1. Elevate arterial blood pressure to high normal ranges (15-20% above upper limits).
2. Ca++ channel blockers (nimodipine).
It has vasodilator effect especially on cerebral vessels, so it protects against focal ischemia.
3. Decrease the ICP by dehydrating measures.
Intraoperative problems:
1- Brain protection measures:
(During the period of carotid clamping).
A- Measures to increase CBF:
1. Elevate arterial blood pressure to high normal ranges (15-20% above upper limits).
2. Ca++ channel blockers (nimodipine).
It has vasodilator effect especially on cerebral vessels, so it protects against focal ischemia.
3. Decrease the ICP by dehydrating measures.
B-Measures to decrease cerebral metabolic rate;
1. Use of isoflurone or sevoflurone (both decrease the critical CBF (which is CBF at which ischemia occurs).
2. Hypothermia (not used nowadays).
3. Anti convulsants.
4. Barbiturates e.g., thiopentone infusion.
It protects against focal not global ischemia.
B-Measures to decrease cerebral metabolic rate;
1. Use of isoflurone or sevoflurone (both decrease the critical CBF (which is CBF at which ischemia occurs).
2. Hypothermia (not used nowadays).
3. Anti convulsants.
4. Barbiturates e.g., thiopentone infusion.
It protects against focal not global ischemia.
Disadvantages: 1. EEG becomes useless monitor.
2. Hypotension and delayed awaking.
C- Other measures: 1. Control of PaCo2.
2. Bypass (temporary shunt).
Between common carotid artery and distal internal carotid artery.
Disadvantages: 1. It doesn't guarantee an adequate CBF.
2. It makes the surgical techniques more difficult.
3. May cause plaque embolization or air embolism.
Disadvantages: 1. EEG becomes useless monitor.
2. Hypotension and delayed awaking.
C- Other measures: 1. Control of PaCo2.
2. Bypass (temporary shunt).
Between common carotid artery and distal internal carotid artery.
Disadvantages: 1. It doesn't guarantee an adequate CBF.
2. It makes the surgical techniques more difficult.
3. May cause plaque embolization or air embolism.
3. Heparinizatin: 5000-10.000 IV heparin IV.
4. Dexmetomidine (2 agonist) has a neuroprotecitive mechanism.
5. Ketamine (a NMDA receptor antagonist).
2- Intraoperative hypo or hypertension.
3- Intraoperative arrhythmias:
a- Reflex bradycardia: due to manipulation of the carotid sinus by the surgeon, treated by: I.V. atropine.
b- Reflex tachycardia:
Treated by: B blockers
3. Heparinizatin: 5000-10.000 IV heparin IV.
4. Dexmetomidine (2 agonist) has a neuroprotecitive mechanism.
5. Ketamine (a NMDA receptor antagonist).
2- Intraoperative hypo or hypertension.
3- Intraoperative arrhythmias:
a- Reflex bradycardia: due to manipulation of the carotid sinus by the surgeon, treated by: I.V. atropine.
b- Reflex tachycardia:
Treated by: B blockers
4- Reperfusion injury: It occurs in the areas distal to the stenotic
lesion which are chronically hypoperfused.
After repair of the carotid stenosis, blood flow to these areas is increased (flow dependent).
Clinical picture: headache, transient ischemic (attack intracerebral haemorrhage.
Treatment: prophylactic by maintaining.
ABP at normal range after the repair of carotid stenosis.
4- Reperfusion injury: It occurs in the areas distal to the stenotic
lesion which are chronically hypoperfused.
After repair of the carotid stenosis, blood flow to these areas is increased (flow dependent).
Clinical picture: headache, transient ischemic (attack intracerebral haemorrhage.
Treatment: prophylactic by maintaining.
ABP at normal range after the repair of carotid stenosis.
5- Intraoperative fluid therapy:
Limited: 10 ml/kg/h.
Types: normal saline or lactated ringer.
With replacement of blood loss.
Avoid dextrose as hyperglycemia worsens the neurologic outcome after cerebral ischemia.
Recovery:
Smooth, early assessment of neurologic outcome.
5- Intraoperative fluid therapy:
Limited: 10 ml/kg/h.
Types: normal saline or lactated ringer.
With replacement of blood loss.
Avoid dextrose as hyperglycemia worsens the neurologic outcome after cerebral ischemia.
Recovery:
Smooth, early assessment of neurologic outcome.
Postoperative management: Postoperative complications: 1) Delayed recovery from general anesthesia: Exclude causes as: hypoglycemia, hyperglycemia,
hypoxia, hypercarbia. Patency of the carotid artery repairs should be
checked by Doppler studies. Search for other causes e.g.:
Intraoperative embolism, thrombosis. Recurrent stenosis. Intracerebral haemorrhage.
2) Appearance of new neurological deficit: e.g., cranial nerve dysfunction. Recurrent laryngeal
nerve injury.
Postoperative management: Postoperative complications: 1) Delayed recovery from general anesthesia: Exclude causes as: hypoglycemia, hyperglycemia,
hypoxia, hypercarbia. Patency of the carotid artery repairs should be
checked by Doppler studies. Search for other causes e.g.:
Intraoperative embolism, thrombosis. Recurrent stenosis. Intracerebral haemorrhage.
2) Appearance of new neurological deficit: e.g., cranial nerve dysfunction. Recurrent laryngeal
nerve injury.
3- Hemodynamic instability: A) Hypertension: Causes: Pain, hypoxia, hypercarbia or full bladder.
Blunting to carotid baroreceptor mechanisms secondary to carotid sinus dysfunction induced by surgical trauma or local anesthetic.
Complications: Myocardial infarction or arrhythmias. Bleeding at the operative site. Intracerebral haemorrhage.
Treatment: Maintain postoperative ABP at the low normal range by: Treatment of the cause. Antihypertensive drugs: e.g., hydralayzine,
propranotal, esmolol or labetalol.
3- Hemodynamic instability: A) Hypertension: Causes: Pain, hypoxia, hypercarbia or full bladder.
Blunting to carotid baroreceptor mechanisms secondary to carotid sinus dysfunction induced by surgical trauma or local anesthetic.
Complications: Myocardial infarction or arrhythmias. Bleeding at the operative site. Intracerebral haemorrhage.
Treatment: Maintain postoperative ABP at the low normal range by: Treatment of the cause. Antihypertensive drugs: e.g., hydralayzine,
propranotal, esmolol or labetalol.
B) Hypotension: Causes: Hypovolemia and residual effects of
anesthetics. Myocardial ischemia and cardiac arrhythmias.
Residual effects of intraoperative antihypertensive drugs.
Increased sensitivity of the carotid sinus.
Treatment:
1. Treatment of the cause.
2. If it is due to increased sensitivity of the carotid sinus, i.v. fluids and inotropes.
B) Hypotension: Causes: Hypovolemia and residual effects of
anesthetics. Myocardial ischemia and cardiac arrhythmias.
Residual effects of intraoperative antihypertensive drugs.
Increased sensitivity of the carotid sinus.
Treatment:
1. Treatment of the cause.
2. If it is due to increased sensitivity of the carotid sinus, i.v. fluids and inotropes.
4- Respiratory insufficiency:
Vocal cord paralysis; due to traction on the recurrent
laryngeal nerve, treated by immediate reintubation.
Neck hematoma, needs immediate evacuation.
Neck edema.
Phrenic nerve paralysis: due to cervical plexus block.
5- Tension pneumotharax:
Cause: Air dissecting through the wound and
mediastinum to the pleura.
4- Respiratory insufficiency:
Vocal cord paralysis; due to traction on the recurrent
laryngeal nerve, treated by immediate reintubation.
Neck hematoma, needs immediate evacuation.
Neck edema.
Phrenic nerve paralysis: due to cervical plexus block.
5- Tension pneumotharax:
Cause: Air dissecting through the wound and
mediastinum to the pleura.
6- Lack of chemoreceptor function:
Cause: carotid body damage; so there is
loss of circulatory response to hypoxia,
hypercarbia with increased resting
PaCo2 by 6 mmHg above the normal.
Treatment: O2 supplementation to all
patients postoperatively.
Opioid are administered cautiously.
6- Lack of chemoreceptor function:
Cause: carotid body damage; so there is
loss of circulatory response to hypoxia,
hypercarbia with increased resting
PaCo2 by 6 mmHg above the normal.
Treatment: O2 supplementation to all
patients postoperatively.
Opioid are administered cautiously.
Minimally invasive carotid artery revascularization:
It is done by percutaneous intervention for carotid angioplasty and stenting via femoral artery approach.
Anesthetic technique
1. Sedation with the use of anticholinergic.
2. General anesthesia if direct common carotid artery is used with full monitoring.
Minimally invasive carotid artery revascularization:
It is done by percutaneous intervention for carotid angioplasty and stenting via femoral artery approach.
Anesthetic technique
1. Sedation with the use of anticholinergic.
2. General anesthesia if direct common carotid artery is used with full monitoring.
