Question
During surgery for aortic arch aneurysm under deep hypothermic circulatory arrest, which of the following anesthetic agent administered prior to circulatory arrest that also provides cerebral protection?
| A. |
Etomidate
|
| B. |
Thiopental sodium
|
| C. |
Propofol
|
| D. |
Ketamine
|
Show Answer
|
Correct Answer » B
Explanation
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|
- Deep hypothermic circulatory arrest (DHCA)is used during complex cardiovascular procedures such as:
- Aortic arch aneurysm repair.
- Aortic dissection surgery.
- Complex congenital cardiac surgery.
- During DHCA, systemic circulation is temporarily stopped while the patient is cooled to 18–20°C.
- Since cerebral blood flow ceases during circulatory arrest, neuroprotective strategies are essential to minimize ischemic brain injury.
Explanation of the Correct Answer
Option B. Thiopental sodium – Correct
- Thiopental sodium is commonly administered before circulatory arrest to provide cerebral protection.
- It reduces:
- Cerebral metabolic rate for oxygen (CMRO₂).
- Cerebral oxygen consumption.
- Cerebral blood flow.
- It produces electroencephalographic (EEG) burst suppression, thereby reducing neuronal metabolic demand during the period of absent cerebral perfusion.
- Thiopental, combined with deep hypothermia, prolongs the brain’s tolerance to ischemia during circulatory arrest.
Why the Other Options are Incorrect
Option A. Etomidate
- Etomidate decreases cerebral metabolic rate and intracranial pressure.
- However, it is not routinely used as a cerebral protective agent during DHCA.
Option C. Propofol
- Propofol also reduces cerebral metabolic rate and cerebral blood flow.
- Although it has neuroprotective properties, thiopental has traditionally been the preferred agent for cerebral protection during deep hypothermic circulatory arrest.
Option D. Ketamine
- Ketamine increases cerebral blood flow and cerebral metabolic activity.
- It is not used for cerebral protection during DHCA.
