A 45-year-old woman who sustained a subarachnoid hemorrhage 18 hours ago develops a severe headache and becomes unresponsive. Which of the following is the most likely cause of this patient's change in mental status?
A 50-year-old patient is undergoing craniotomy for clipping of a cerebral aneurysm with isoflurane, nitrous oxide, and fentanyl anesthesia. At the time of aneurysm exposure, the EEG shows burst suppression. Which of the following is the most likely cause?
Immediately after sustaining severe head injury, a 20-year-old man has a blood pressure of 150/90 mmHg and an intracranial pressure of 35 mmHg. After one hour of thiopental infusion, blood pressure is 105/60 mmHg, intracranial pres sure is 20 mmHg, central venous pressure is 5 mmHg, and temperature is 36°C. The EEG shows slow-wave activity. The most appropriate next step is administration of
A multi-orifices right heart catheter is being positioned by EKG control prior to sitting craniotomy. The EKG tracing is obtained between the distal tip of the catheter and the right arm lead. The most appropriate next step is to
A patient who is receiving ventilatory support after coronary artery bypass grafting has a PaO2 of 132 mmHg, a PaCO2 of 19 mmHg, and a pH of 7.57. Which of the following is most likely to result from this level of hypocarbia?
A 6-year-old boy undergoes craniotomy in the supine position for brain tumor during anesthesia with 1.5% isoflurane in oxygen. PetCO2 is 38 mmHg, heart rate is 78 bpm, and blood pressure is 130/80 mmHg. After opening the dura, the surgeon notes that the brain is bulging. Which of the following management options is LEAST likely to significantly decrease brain size?
During a craniotomy for a supratentorial tumor, a 28-year-old man receives isoflurane 0.75% in nitrous oxide 70% and oxygen. Ventilation is controlled to maintain PaCO2 at 25 mmHg. Nasopharyngeal temperature is 35.8°C. While the dura mater is open, the surgeon complains that the brain is bulging. The most appropriate management at this time is to
(A) decrease the inspired isoflurane concentration to 0.5%
(B) hyperventilate further to decrease PaCO2 to 20 mmHg
The following changes occur during posterior cervical fusion in the prone position under halothane and nitrous oxide anesthesia with mechanical ventilation: HR 78 --> 84 with frequent PVCs; BP 110/70 --> 90/50; EtCO2 4.5% --> 2.0%; EtN2 0.12% --> 4% The most appropriate next step is to
A 50-year-old man is scheduled to undergo emergency craniotomy for evacuation of an epidural hematoma. His Glasgow Coma Scale score is 6; heart rate is 54 bpm, and blood pressure is 190/110 mmHg. The most appropriate initial management is administration of which of the following agents?
A 70-kg, 46-year-old man is undergoing clipping of a cerebral aneurysm with nitrous oxide, opioid, relaxant anesthesia. He is otherwise healthy. As the surgeons are about to enter the dura, the brain is noted to be tense and bulging. Heart rate is 100 bpm and mean arterial pressure is 90 mmHg. PaO2 is 120 mmHg, PaCO2 is 23 mmHg, and pH is 7.50. Which of the following should be done immediately?
(A) Hyperventilation to a PaCO2 of 15 to 20 mmHg
(B) Administration of furosemide 20 mg intravenously
(C) Administration of mannitol 0.5 g/kg
(D) Administration of thiopental 250 mg in increments
Massive venous air embolism occurs in a patient who is undergoing craniotomy in the sitting position with nitrous oxide, oxygen, fentanyl anesthesia. Which of the following changes in end-tidal (ET) concentrations of carbon dioxide, nitrogen, and nitrous oxide are most likely in this patient? (ETCO2, ETN2, ETN2O)
A 4-month-old child undergoing a craniectomy for craniosynostosis is anesthetized with nitrous oxide and halothane. Suddenly the systolic blood pressure decreases from 75 to 30 mmHg, and the PetCO2 decreases from 35 to 6 mmHg. Which of the following maneuvers is LEAST likely to have a beneficial effect?
(A) Administration of a fluid bolus
(B) Administration of a vasopressor
(C) Application of positive end-expiratory pressure
(D) Discontinuation of nitrous oxide
(E) Flooding the surgical wound with saline solution
A 32-year-old woman is anesthetized for suboccipital craniotomy. During positioning, the capnograph shows an abrupt decrease in the slope of the expiratory upstroke. Which of the following is the most likely cause?
A 30-year-old man who is breathing spontaneously has a ventilatory pattern of sustained deep inspiration and occasional expiratory gasps during emergence from general anesthesia after posterior fossa craniotomy. Which of the following is the most likely cause?
A 62-year-old man is in the intensive care unit after successful craniotomy for excision of a meningioma. Blood volume is normal; laboratory studies show serum sodium concentration of 120 mEq/L, serum osmolality of 260 mOsm/L, urine sodium concentration of 50 mEq/L, and urine osmolality of 820 mOsm/L. Which of the following is the most likely explanation?
(A) Fluid overload with 5% dextrose in water
(B) Inappropriate secretion of antidiuretic hormone
One hour after induction of anesthesia for a posterior fossa craniotomy using opioid, relaxant, and nitrous oxide, the brain begins to protrude through the dura. The most effective measure to decrease intracranial pressure is to
A neurologically intact 48-year-old woman is scheduled for removal of a parietal lobe arteriovenous malformation. The relative risk for complete resection is to be determined by a test occlusion of the feeding artery. Which of the following intraoperative monitoring techniques is most appropriate for this test?
(A) Brain stem auditory evoked potentials
(B) Cerebral blood flow using radioactive xenon
(D) Evoked potentials elicited by stimulating the posterior tibial nerve
A 35-year-old woman with a grade III subarachnoid hemorrhage is undergoing clipping of a middle cerebral artery aneurysm 48 hours after initial hemorrhage. Which of the following drugs used to induce hypotension is LEAST likely to affect intracranial pressure?
In a patient receiving an epidural analgesic infusion postoperatively, clear fluid is noted to drip back freely from the epidural catheter. Each of the following findings correctly identifies the associated fluid EXCEPT
(A) precipitation when mixed with an equal volume of thiopental — local anesthetic
A 48-year-old woman underwent a posterior fossa craniotomy in the sitting position. Monitoring included precordial Doppler, arterial blood pressure, central venous pressure (CVP), and urine output. Furosemide was used intraopera-tively for cerebral decompression, and the operation was uneventful. In the recovery room, she was awake with stable vital signs when the CVP suddenly increased from 6 to 25 mmHg without any change in blood pressure. Shortly thereafter, premature ventricular contractions are noted. After administering lidocaine 1 mg/kg intravenously, the most appropriate action is to
(A) position the patient head down, right side up and aspirate the CVP catheter
(B) withdraw the CVP catheter 5 cm
(C) infuse potassium chloride rapidly
(D) administer furosemide
(E) ask the neurosurgeon to reevaluate the patient immediately
An otherwise healthy 16-year-old girl is undergoing posterior spinal fusion for thoracolumbar scoliosis. During the procedure, the most likely cause of a marked decrease in the amplitude of the somatosensory evoked potentials after stimulation of the posterior tibial nerve is
(A) administration of fentanyl 30 jag /kg for induction
(B) administration of isoflurane 1.3 MAC for maintenance
(C) administration of vecuronium 0.15 mg/kg
(D) a decrease in body temperature from 37 to 35°C