EDAIC Respiratory and Thoracic Anesthesia 4 — Questions and Answers
Question 1: During mediastinoscopy, the surgeon reports loss of the right radial pulse. The most likely cause is:
- Inadvertent right subclavian artery ligation
- Compression of the innominate (brachiocephalic) artery by the mediastinoscope (Correct answer)
- Systemic hypotension from vagal stimulation
- Right arm venous tourniquet effect from patient positioning
Correct answer: Compression of the innominate (brachiocephalic) artery by the mediastinoscope
The mediastinoscope can compress the innominate artery against the trachea, reducing right-sided perfusion; pulse oximetry on the right hand detects this before serious sequelae occur.
Question 2: Which statement about the use of PEEP during one-lung ventilation is TRUE?
- PEEP should never be applied to avoid worsening HPV
- PEEP on the ventilated lung reduces shunt by recruiting collapsed alveoli (Correct answer)
- PEEP uniformly improves oxygenation in all OLV patients
- PEEP to the dependent lung is contraindicated when PVR is elevated
Correct answer: PEEP on the ventilated lung reduces shunt by recruiting collapsed alveoli
Judicious PEEP (5 cmH2O) to the ventilated dependent lung recruits atelectatic alveoli and improves V/Q matching, though excessive PEEP can increase PVR and worsen hypoxemia.
Question 3: A fiberoptic bronchoscope confirms the right upper lobe bronchial orifice is blocked by the bronchial cuff of a right-sided double-lumen tube. The correct initial action is:
- Deflate the bronchial cuff and withdraw the tube 1-2 cm (Correct answer)
- Replace with a left-sided DLT immediately
- Advance the tube further into the right bronchus
- Increase the tidal volume to overcome the obstruction
Correct answer: Deflate the bronchial cuff and withdraw the tube 1-2 cm
The right upper lobe bronchus originates close to the carina; partial withdrawal with cuff deflation allows the RUL orifice to align with the tube's ventilation slot.
Question 4: Hypoxic pulmonary vasoconstriction is blunted by all of the following EXCEPT:
- Vasodilators (e.g., nitroglycerin, nitroprusside)
- Hypothermia
- Acidosis (Correct answer)
- Volatile anesthetic agents at >1 MAC
Correct answer: Acidosis
Acidosis actually potentiates HPV rather than inhibiting it; vasodilators, hypothermia, and volatile agents at high concentrations are all recognized HPV inhibitors.
Question 5: Postoperative analgesia after VATS resection is MOST commonly managed with:
- Thoracic epidural analgesia
- Intercostal nerve blocks combined with systemic opioids
- Paravertebral block (Correct answer)
- IV ketamine infusion alone
Correct answer: Paravertebral block
Paravertebral blocks provide unilateral segmental analgesia comparable to thoracic epidural analgesia with fewer side effects (hypotension, urinary retention) and are preferred for VATS procedures.
Question 6: In a patient with a bronchopleural fistula requiring general anesthesia, the safest initial airway management strategy is:
- Rapid sequence induction with succinylcholine and immediate intubation
- Awake fiberoptic intubation with a double-lumen tube before induction (Correct answer)
- High-frequency jet ventilation via a rigid bronchoscope
- Mask induction with sevoflurane to spontaneous ventilation
Correct answer: Awake fiberoptic intubation with a double-lumen tube before induction
Awake intubation with a DLT isolates the fistula side before positive pressure is applied, preventing massive air leak and tension pneumothorax under anesthesia.
Question 7: The oxyhemoglobin dissociation curve is shifted to the RIGHT by which combination of factors particularly relevant during thoracic surgery?
- Alkalosis, hypothermia, decreased 2,3-DPG
- Acidosis, hyperthermia, increased 2,3-DPG (Correct answer)
- Alkalosis, hyperthermia, decreased 2,3-DPG
- Acidosis, hypothermia, increased 2,3-DPG
Correct answer: Acidosis, hyperthermia, increased 2,3-DPG
Acidosis, increased temperature, and elevated 2,3-DPG all reduce hemoglobin's oxygen affinity (Bohr effect), facilitating oxygen unloading to tissues during periods of increased demand.
EDAIC Respiratory and Thoracic Anesthesia 4
During mediastinoscopy, the surgeon reports loss of the right radial pulse.
The most likely cause is: