Which of the following statements concerning the choice of nitroprusside or nitroglycerin to induce deliberate hypotension is true?
(A) Nitroglycerin is more potent
(B) Nitroglycerin produces hypotension by acting on both arterial and venous capacitance vessels
(C) Nitroprusside produces less rebound hypertension on discontinuation
(D) The toxic effects of nitroprusside are independent of dose
(E) The therapeutic effects of nitroprusside may persist on discontinuation
B
An elderly man has an acute dissection of the descending thoracic aorta. Which of the following antihypertensive therapies is most likely to extend the dissection?
(A) Esmolol infusion
(B) Nitroglycerin infusion
(C) Nitroprusside infusion
(D) Nitroprusside infusion combined with a beta-adrenergic blocker
Three hours prior to induction of anesthesia for elective laparotomy, a 40-kg 8-year-old boy is anxious and clings to his parents. Which of the following preanesthetic medications is most appropriate?
A 62-year-old woman with polycythemia vera is scheduled to undergo total knee arthroplasty using a tourniquet. Preoperative hematocrit is 60%. Which of the following is the most appropriate action?
(A) Perform total knee arthroplasty without use of a tourniquet
(B) Preoperative reduction of the hematocrit to 45% to 50%
(C) Prophylactic administration of aprotonin during surgery
(D) Prophylactic administration of epsilon-aminocaproic acid during surgery
(E) Prophylactic administration of low-dose heparin during surgery
B
For 30 minutes, a patient has been receiving oxygen 2 L, nitrous oxide 2 L, and halothane from an agent-specific vaporizer set at 1%. A mass spectrometer sampling gas from the patient's airway shows an end-tidal halothane concentration of 0.7%. The most likely explanation for this difference is
A 14-year-old girl with status asthmaticus is receiving oxygen 3 L/min through nasal prongs. Heart rate is 110 bpm. Arterial blood gas values are PaO2 90 mmHg, PaCO2 32 mmHg, and pH 7.46. If ventilation appears unchanged, which of the following is the most reliable sign of impending respiratory failure?