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A 71-year-old female patient with carotid endarterectomy in Yao's Anesthesiology
.
Carotid endarterectomy (CEA) was proposed for asymptomatic left internal carotid artery stenosis.
The patient's left carotid artery was 90% occluded
.
Past medical history: hypertension, insulin-dependent diabetes mellitus and coronary heart disease (angioplasty was performed 2 years ago)
.
The patient's blood pressure is 180/75mmHg, and the pulse rate is 65 beats per minute, all of which are regular
.
A.
Diseases and differential diagnosis 1.
What are the clinical manifestations of carotid artery stenosis? 2.
What is the incidence of carotid artery disease? 3.
What is the natural course of carotid artery disease? 4.
Discussion Diabetes is one of the risk factors of carotid endarterectomy
.
5.
What are the indications for surgical treatment of carotid atherosclerosis? 6.
Briefly describe the anatomy of intracranial blood vessels.
Including carotid artery and circle of Willis
.
7.
Briefly describe the cerebral blood perfusion in patients with carotid artery disease
.
8.
Briefly describe the different surgical methods for carotid artery revascularization
.
9.
What is the normal cerebral blood flow? 10.
The definition of very low cerebral blood flow under EEG monitoring
.
11.
What is the automatic regulation mechanism of cerebral blood flow? 12.
What is the effect of partial pressure of carbon dioxide (PaCO2) on cerebral blood flow? 13.
What are the main determinants of cerebral blood flow? 14.
What is the definition of overperfusion? 15.
What is the definition of intracranial blood steal syndrome? 16.
What is the definition of "anti-blood syndrome" or "Robin-Hood syndrome"? B.
Preoperative evaluation and preparation 1.
What is the content of preoperative evaluation? 2.
For elective surgery, is the patient's blood pressure too high? 3.
What are the laboratory tests required before surgery? 4.
Do such patients need preoperative medication? Partial answers A.
Diseases and differential diagnosis A5.
What are the indications for surgical treatment of carotid atherosclerosis? • Transient ischemic attack with evidence of vascular stenosis
.
• More than 70% of the lumen is narrowed, and there are reversible ischemic neurological deficits; or ulcerative plaques regardless of whether it is accompanied by lumen stenosis
.
• In the case of anticoagulation, continuous neurological instability
.
A6.
Briefly describe the anatomy of intracranial blood vessels, including carotid artery and circle of Willis
.
①The common carotid artery originates from the thoracic cavity
.
The right common carotid artery originates from the bifurcation of the brachiocephalic trunk, and the left common carotid artery originates from the aortic arch
.
In the neck, the common carotid artery runs in the carotid sheath
.
At the level of the thyroid cartilage, the common carotid artery is divided into internal and external carotid arteries
.
②Branches of external carotid artery: superior thyroid artery, lingual artery, facial artery, ascending pharyngeal artery, occipital artery and posterior auricular artery
.
③The internal carotid artery has no branches in the neck.
It enters the middle cranial fossa through the carotid tube of the temporal bone (next to the sphenoid bone), and supplies the pituitary gland, the orbit and most of the supratentorial area of the brain
.
The cerebral artery originates from the internal carotid artery and the vertebral artery, and forms the circle of Willis at the base of the brain through the communicating branches
.
The anterior cerebral artery forms the front part of the circle of Willis and is connected by the anterior communicating artery
.
The posterior cerebral artery forms the back of the circle of Willis and ends at the confluence of the two basilar arteries
.
The posterior cerebral artery is connected to the internal carotid artery through the posterior communicating artery (Figure 23-1).
The middle cerebral artery supplies the lateral surface of the cerebral hemisphere
.
The anterior cerebral artery and the posterior cerebral artery supply the inner surface and lower part of the cerebral hemisphere
.
A7.
Briefly describe the cerebral blood perfusion in patients with carotid artery disease
.
The brain tissue on the verge of ischemia loses its automatic regulation of cerebral blood flow
.
Chronic hypoperfusion or relatively ischemic brain tissue has the largest expansion of the vascular bed and is not sensitive to vasoactive factors that can cause normal vasoconstriction
.
Therefore, for patients with carotid artery disease, the blood flow of brain tissue in the ischemic area depends on the systolic blood pressure, which is passive
.
Because of this, hypotension should be avoided as much as possible before cerebral blood flow is reestablished
.
A8.
Briefly describe the different surgical methods for carotid artery revascularization
.
Carotid endarterectomy refers to the removal of atherosclerotic plaques in the lumen through standardized surgical procedures
.
The surgical procedure includes: blocking the common carotid artery, external carotid artery, and internal carotid artery, freeing the blood vessel of the diseased segment, opening the blood vessel wall, removing the plaque, and then suturing the blood vessel wall
.
If the intima of the remaining blood vessel is very thin, a vein graft or a synthetic vascular patch is required to suture the blood vessel
.
Whether shunt is performed when the internal carotid artery is blocked depends on whether the symptoms of cerebral ischemia are obvious after the carotid artery is blocked
.
Shunt ensures the blood supply to the cerebral hemispheres during carotid artery occlusion, which is especially suitable for complicated and long-term endarterectomy
.
Another method to treat carotid artery stenosis is percutaneous transluminal angioplasty and stent implantation performed by interventional radiologists
.
A11.
What is the automatic regulation mechanism of cerebral blood flow? The auto-regulation mechanism of cerebral blood flow refers to that when blood pressure fluctuates within a certain range, brain tissue regulates itself to ensure normal blood supply
.
In individuals with normal blood pressure, the cerebral blood flow remains stable when the mean arterial pressure is 50-150mmHg
.
The auto-regulation mechanism of cerebral blood flow in hypertensive patients still exists, but the upper and lower limits of the auto-regulation curve shift to the right
.
This suggests that when the average arterial pressure is 60mmHg, individuals with normal blood pressure can tolerate it well, but this value may be lower than the lower limit of hypertensive patients, resulting in hypoperfusion of brain tissue
.
In contrast, patients with hypertension can better tolerate higher blood pressure
.
After treatment for hypertensive patients, the automatic adjustment threshold returns to normal
.
A12.
What is the effect of partial pressure of carbon dioxide (PaCO2) on cerebral blood flow? Hypercapnia causes cerebral blood vessels to dilate, while hypocapnia causes cerebral blood vessels to constrict
.
When the partial pressure of arterial carbon dioxide is in the range of 20-80 mmHg, the cerebral blood flow changes by 4% for every increase or decrease of 1 mmHg
.
A13.
What are the main determinants of cerebral blood flow? Including: neuronal cell activity, cerebral perfusion pressure, carbon dioxide partial pressure, pH value of extracellular fluid of brain tissue, oxygen partial pressure and neurogenic effects
.
A15.
What is the definition of intracranial blood steal syndrome? Intracranial blood stealing refers to the decrease of cerebral blood flow in ischemic brain tissue under the condition of hypercapnia
.
This is due to carbon dioxide acting on the normally perfused small arteries around the ischemic area
.
Due to the maximum expansion of the vascular bed of chronic ischemic brain tissue, there is no response to hypercapnia
.
B.
Preoperative evaluation and preparation Bl.
What is the content of preoperative evaluation? First, determine whether the patient has other manifestations of systemic atherosclerosis, such as coronary heart disease, hypertension, or kidney disease
.
In addition, diseases related to atherosclerosis should also be considered, such as obesity, diabetes, and pulmonary vascular diseases caused by smoking
.
At the same time, the patient's airway and nervous system functional status should also be evaluated
.
B2.
For elective surgery, is the patient's blood pressure too high? ①Although most patients undergoing carotid endarterectomy have hypertension, it is generally not recommended to correct blood pressure quickly, otherwise it will aggravate cerebral ischemia
.
If the patient has symptoms of myocardial ischemia at a certain blood pressure level, but cerebral blood perfusion can be ensured, antihypertensive drugs should be used to slowly decrease blood pressure
.
②The function of the patient's normal myocardium and brain tissue should be preserved
.
Lowering heart rate, blood pressure and myocardial contractility can reduce myocardial oxygen consumption, but sufficient mean arterial pressure must be ensured to maintain normal cerebral blood perfusion
.
③A single preoperative blood pressure is of little use for preoperative evaluation
.
Perioperative blood pressure control should be carried out according to the range of blood pressure fluctuation that the patient can tolerate
.
④The anesthesiologist should prepare vasoconstrictors and dilators to minimize the range of blood pressure fluctuations and reduce the occurrence of complications of the heart and nervous system
.
B3.
What are the laboratory tests required before surgery? Relevant examinations should be performed before surgery to assess the basic state of the patient's heart, lung and metabolic functions
.
ECG, chest radiograph
.
Arterial blood gas understands the patient's basic carbon dioxide partial pressure
.
For patients with chronic hypercapnia, if the partial pressure of carbon dioxide drops to normal during the operation, the body will regard it as hypocapnia and the cerebral blood flow will decrease
.
During the operation, the arterial partial pressure of carbon dioxide was maintained at the patient's "normal" level by adjusting the mechanical ventilation parameters
.
For more details, please see the next breakdown
.
Carotid endarterectomy (CEA) was proposed for asymptomatic left internal carotid artery stenosis.
The patient's left carotid artery was 90% occluded
.
Past medical history: hypertension, insulin-dependent diabetes mellitus and coronary heart disease (angioplasty was performed 2 years ago)
.
The patient's blood pressure is 180/75mmHg, and the pulse rate is 65 beats per minute, all of which are regular
.
A.
Diseases and differential diagnosis 1.
What are the clinical manifestations of carotid artery stenosis? 2.
What is the incidence of carotid artery disease? 3.
What is the natural course of carotid artery disease? 4.
Discussion Diabetes is one of the risk factors of carotid endarterectomy
.
5.
What are the indications for surgical treatment of carotid atherosclerosis? 6.
Briefly describe the anatomy of intracranial blood vessels.
Including carotid artery and circle of Willis
.
7.
Briefly describe the cerebral blood perfusion in patients with carotid artery disease
.
8.
Briefly describe the different surgical methods for carotid artery revascularization
.
9.
What is the normal cerebral blood flow? 10.
The definition of very low cerebral blood flow under EEG monitoring
.
11.
What is the automatic regulation mechanism of cerebral blood flow? 12.
What is the effect of partial pressure of carbon dioxide (PaCO2) on cerebral blood flow? 13.
What are the main determinants of cerebral blood flow? 14.
What is the definition of overperfusion? 15.
What is the definition of intracranial blood steal syndrome? 16.
What is the definition of "anti-blood syndrome" or "Robin-Hood syndrome"? B.
Preoperative evaluation and preparation 1.
What is the content of preoperative evaluation? 2.
For elective surgery, is the patient's blood pressure too high? 3.
What are the laboratory tests required before surgery? 4.
Do such patients need preoperative medication? Partial answers A.
Diseases and differential diagnosis A5.
What are the indications for surgical treatment of carotid atherosclerosis? • Transient ischemic attack with evidence of vascular stenosis
.
• More than 70% of the lumen is narrowed, and there are reversible ischemic neurological deficits; or ulcerative plaques regardless of whether it is accompanied by lumen stenosis
.
• In the case of anticoagulation, continuous neurological instability
.
A6.
Briefly describe the anatomy of intracranial blood vessels, including carotid artery and circle of Willis
.
①The common carotid artery originates from the thoracic cavity
.
The right common carotid artery originates from the bifurcation of the brachiocephalic trunk, and the left common carotid artery originates from the aortic arch
.
In the neck, the common carotid artery runs in the carotid sheath
.
At the level of the thyroid cartilage, the common carotid artery is divided into internal and external carotid arteries
.
②Branches of external carotid artery: superior thyroid artery, lingual artery, facial artery, ascending pharyngeal artery, occipital artery and posterior auricular artery
.
③The internal carotid artery has no branches in the neck.
It enters the middle cranial fossa through the carotid tube of the temporal bone (next to the sphenoid bone), and supplies the pituitary gland, the orbit and most of the supratentorial area of the brain
.
The cerebral artery originates from the internal carotid artery and the vertebral artery, and forms the circle of Willis at the base of the brain through the communicating branches
.
The anterior cerebral artery forms the front part of the circle of Willis and is connected by the anterior communicating artery
.
The posterior cerebral artery forms the back of the circle of Willis and ends at the confluence of the two basilar arteries
.
The posterior cerebral artery is connected to the internal carotid artery through the posterior communicating artery (Figure 23-1).
The middle cerebral artery supplies the lateral surface of the cerebral hemisphere
.
The anterior cerebral artery and the posterior cerebral artery supply the inner surface and lower part of the cerebral hemisphere
.
A7.
Briefly describe the cerebral blood perfusion in patients with carotid artery disease
.
The brain tissue on the verge of ischemia loses its automatic regulation of cerebral blood flow
.
Chronic hypoperfusion or relatively ischemic brain tissue has the largest expansion of the vascular bed and is not sensitive to vasoactive factors that can cause normal vasoconstriction
.
Therefore, for patients with carotid artery disease, the blood flow of brain tissue in the ischemic area depends on the systolic blood pressure, which is passive
.
Because of this, hypotension should be avoided as much as possible before cerebral blood flow is reestablished
.
A8.
Briefly describe the different surgical methods for carotid artery revascularization
.
Carotid endarterectomy refers to the removal of atherosclerotic plaques in the lumen through standardized surgical procedures
.
The surgical procedure includes: blocking the common carotid artery, external carotid artery, and internal carotid artery, freeing the blood vessel of the diseased segment, opening the blood vessel wall, removing the plaque, and then suturing the blood vessel wall
.
If the intima of the remaining blood vessel is very thin, a vein graft or a synthetic vascular patch is required to suture the blood vessel
.
Whether shunt is performed when the internal carotid artery is blocked depends on whether the symptoms of cerebral ischemia are obvious after the carotid artery is blocked
.
Shunt ensures the blood supply to the cerebral hemispheres during carotid artery occlusion, which is especially suitable for complicated and long-term endarterectomy
.
Another method to treat carotid artery stenosis is percutaneous transluminal angioplasty and stent implantation performed by interventional radiologists
.
A11.
What is the automatic regulation mechanism of cerebral blood flow? The auto-regulation mechanism of cerebral blood flow refers to that when blood pressure fluctuates within a certain range, brain tissue regulates itself to ensure normal blood supply
.
In individuals with normal blood pressure, the cerebral blood flow remains stable when the mean arterial pressure is 50-150mmHg
.
The auto-regulation mechanism of cerebral blood flow in hypertensive patients still exists, but the upper and lower limits of the auto-regulation curve shift to the right
.
This suggests that when the average arterial pressure is 60mmHg, individuals with normal blood pressure can tolerate it well, but this value may be lower than the lower limit of hypertensive patients, resulting in hypoperfusion of brain tissue
.
In contrast, patients with hypertension can better tolerate higher blood pressure
.
After treatment for hypertensive patients, the automatic adjustment threshold returns to normal
.
A12.
What is the effect of partial pressure of carbon dioxide (PaCO2) on cerebral blood flow? Hypercapnia causes cerebral blood vessels to dilate, while hypocapnia causes cerebral blood vessels to constrict
.
When the partial pressure of arterial carbon dioxide is in the range of 20-80 mmHg, the cerebral blood flow changes by 4% for every increase or decrease of 1 mmHg
.
A13.
What are the main determinants of cerebral blood flow? Including: neuronal cell activity, cerebral perfusion pressure, carbon dioxide partial pressure, pH value of extracellular fluid of brain tissue, oxygen partial pressure and neurogenic effects
.
A15.
What is the definition of intracranial blood steal syndrome? Intracranial blood stealing refers to the decrease of cerebral blood flow in ischemic brain tissue under the condition of hypercapnia
.
This is due to carbon dioxide acting on the normally perfused small arteries around the ischemic area
.
Due to the maximum expansion of the vascular bed of chronic ischemic brain tissue, there is no response to hypercapnia
.
B.
Preoperative evaluation and preparation Bl.
What is the content of preoperative evaluation? First, determine whether the patient has other manifestations of systemic atherosclerosis, such as coronary heart disease, hypertension, or kidney disease
.
In addition, diseases related to atherosclerosis should also be considered, such as obesity, diabetes, and pulmonary vascular diseases caused by smoking
.
At the same time, the patient's airway and nervous system functional status should also be evaluated
.
B2.
For elective surgery, is the patient's blood pressure too high? ①Although most patients undergoing carotid endarterectomy have hypertension, it is generally not recommended to correct blood pressure quickly, otherwise it will aggravate cerebral ischemia
.
If the patient has symptoms of myocardial ischemia at a certain blood pressure level, but cerebral blood perfusion can be ensured, antihypertensive drugs should be used to slowly decrease blood pressure
.
②The function of the patient's normal myocardium and brain tissue should be preserved
.
Lowering heart rate, blood pressure and myocardial contractility can reduce myocardial oxygen consumption, but sufficient mean arterial pressure must be ensured to maintain normal cerebral blood perfusion
.
③A single preoperative blood pressure is of little use for preoperative evaluation
.
Perioperative blood pressure control should be carried out according to the range of blood pressure fluctuation that the patient can tolerate
.
④The anesthesiologist should prepare vasoconstrictors and dilators to minimize the range of blood pressure fluctuations and reduce the occurrence of complications of the heart and nervous system
.
B3.
What are the laboratory tests required before surgery? Relevant examinations should be performed before surgery to assess the basic state of the patient's heart, lung and metabolic functions
.
ECG, chest radiograph
.
Arterial blood gas understands the patient's basic carbon dioxide partial pressure
.
For patients with chronic hypercapnia, if the partial pressure of carbon dioxide drops to normal during the operation, the body will regard it as hypocapnia and the cerebral blood flow will decrease
.
During the operation, the arterial partial pressure of carbon dioxide was maintained at the patient's "normal" level by adjusting the mechanical ventilation parameters
.
For more details, please see the next breakdown
