BCA BCA Thoracic & Vascular Anesthesia 1 — Questions and Answers
Question 1: During one-lung ventilation (OLV), the MOST common cause of hypoxemia is:
- Excessive tidal volume to the ventilated lung
- Hypoxic pulmonary vasoconstriction failure in the non-ventilated lung (Correct answer)
- CO2 retention
- Endotracheal tube cuff leak
Correct answer: Hypoxic pulmonary vasoconstriction failure in the non-ventilated lung
Impaired hypoxic pulmonary vasoconstriction (HPV) in the non-ventilated (collapsed) lung allows continued blood flow without gas exchange, creating a large intrapulmonary shunt.
Question 2: A double-lumen endotracheal tube (DLT) is placed for left lung surgery. Correct positioning is confirmed by:
- Chest X-ray only
- Clinical auscultation and fiberoptic bronchoscopy (Correct answer)
- Capnography alone
- Pulse oximetry alone
Correct answer: Clinical auscultation and fiberoptic bronchoscopy
Fiberoptic bronchoscopy combined with clinical auscultation is the gold standard for confirming correct DLT position and ensuring adequate lung isolation.
Question 3: During thoracic aortic cross-clamping, the MOST critical consequence of prolonged clamp time is:
- Pulmonary edema
- Spinal cord ischemia leading to paraplegia (Correct answer)
- Renal artery thrombosis
- Hepatic infarction
Correct answer: Spinal cord ischemia leading to paraplegia
Aortic cross-clamping interrupts blood flow to the anterior spinal artery (artery of Adamkiewicz), causing ischemic myelopathy and potential permanent paraplegia.
Question 4: Cerebrospinal fluid (CSF) drainage during thoracic aortic aneurysm repair is used to:
- Prevent PONV
- Reduce spinal cord perfusion pressure
- Increase spinal cord perfusion pressure by lowering CSF pressure (Correct answer)
- Treat intraoperative seizures
Correct answer: Increase spinal cord perfusion pressure by lowering CSF pressure
Draining CSF reduces intrathecal pressure, thereby increasing spinal cord perfusion pressure (SCPP = MAP − CSF pressure) and protecting the spinal cord from ischemia.
Question 5: Which volatile anesthetic MOST inhibits hypoxic pulmonary vasoconstriction (HPV)?
- Sevoflurane at 1 MAC
- Isoflurane at 1 MAC
- Desflurane at 1 MAC
- All volatiles inhibit HPV equally at equipotent doses (Correct answer)
Correct answer: All volatiles inhibit HPV equally at equipotent doses
At equipotent doses (1 MAC), all currently used volatile anesthetics produce similar degrees of HPV inhibition; the clinical significance at typical doses is modest.
Question 6: A patient undergoes pneumonectomy. Postoperative fluid management should be conservative primarily because of the risk of:
- Pulmonary edema in the remaining single lung (Correct answer)
- Deep vein thrombosis
- Hepatic congestion
- Urinary retention
Correct answer: Pulmonary edema in the remaining single lung
After pneumonectomy, all cardiac output passes through a single lung; aggressive fluid administration rapidly overwhelms its vascular capacity, causing post-pneumonectomy pulmonary edema.
BCA BCA Thoracic & Vascular Anesthesia 1
During one-lung ventilation (OLV), the MOST common cause of hypoxemia is: