BCSE Principles of Anesthesia 5 — Questions and Answers
Question 1: A patient develops tachycardia, hyperthermia, muscle rigidity, and rhabdomyolysis after sevoflurane exposure. Temperature is 41°C. What is the immediate treatment?
- Administer dantrolene 2.5 mg/kg IV immediately (Correct answer)
- Cool the patient with ice packs and reassess
- Administer beta-blockers for tachycardia control
- Increase volatile anesthetic concentration to deepen anesthesia
Correct answer: Administer dantrolene 2.5 mg/kg IV immediately
Malignant hyperthermia requires immediate dantrolene (2.5 mg/kg IV, repeat up to 10 mg/kg), discontinuation of triggers, and aggressive cooling.
Question 2: Which monitoring modality is most useful for detecting intraoperative myocardial ischemia?
- Lead II ECG only
- Five-lead ECG with continuous ST-segment monitoring (leads II and V5) (Correct answer)
- Pulmonary artery catheter
- Transesophageal echocardiography wall motion analysis
Correct answer: Five-lead ECG with continuous ST-segment monitoring (leads II and V5)
Combined monitoring of leads II and V5 detects approximately 96% of intraoperative ST-segment changes, covering both inferior and anterior/lateral territory.
Question 3: Opioid-induced hyperalgesia is BEST managed by which strategy?
- Increasing opioid dose to overcome the sensitization
- Opioid rotation and multimodal analgesia with NMDA antagonists (Correct answer)
- Adding benzodiazepines to suppress pain perception
- Switching to acetaminophen monotherapy
Correct answer: Opioid rotation and multimodal analgesia with NMDA antagonists
Opioid rotation plus NMDA antagonists (ketamine, methadone) targets central sensitization underlying opioid-induced hyperalgesia.
Question 4: A patient has a T4 spinal cord injury. During urinary catheter insertion the patient develops hypertension, bradycardia, and diaphoresis. What is occurring?
- Anaphylactic reaction to catheter material
- Autonomic dysreflexia (Correct answer)
- Vasovagal syncope
- Epidural hematoma
Correct answer: Autonomic dysreflexia
Autonomic dysreflexia occurs in SCI above T6 when noxious stimuli below the lesion trigger uncontrolled sympathetic discharge without supraspinal inhibition.
Question 5: Which agent used for controlled hypotension in neuroanesthesia directly donates nitric oxide to produce vasodilation?
- Esmolol
- Labetalol
- Sodium nitroprusside (Correct answer)
- Nicardipine
Correct answer: Sodium nitroprusside
Sodium nitroprusside spontaneously releases nitric oxide, activating guanylyl cyclase and producing rapid, titratable vasodilation.
Question 6: During one-lung ventilation for thoracic surgery, hypoxia develops. What is the FIRST intervention?
- Increase tidal volume on the ventilated lung
- Apply CPAP (5 cmH2O) to the non-ventilated lung (Correct answer)
- Clamp the pulmonary artery to the operative lung
- Convert to two-lung ventilation immediately
Correct answer: Apply CPAP (5 cmH2O) to the non-ventilated lung
Applying low-level CPAP (5 cmH2O) with 100% O2 to the non-ventilated lung recruits alveoli and improves oxygenation without eliminating the surgical field.
Question 7: The MAC (minimum alveolar concentration) of a volatile anesthetic is defined as the concentration that prevents movement in response to surgical stimulus in what percentage of patients?
- 50% (Correct answer)
- 95%
- 99%
- 75%
Correct answer: 50%
MAC is the ED50 — the alveolar concentration preventing movement in 50% of patients exposed to a standard surgical stimulus (skin incision).
BCSE Principles of Anesthesia 5
A patient develops tachycardia, hyperthermia, muscle rigidity, and rhabdomyolysis after sevoflurane exposure.
Temperature is 41°C.
What is the immediate treatment?