Arterial pressure in the radial artery is 155/70 mmHg measured by a correctly calibrated catheter-transducer system. At the same time aortic pressure is 140/75 mmHg using a high-fidelity catheter tip transducer. The most likely cause of this discrepancy is
(A) a large amount of air in the dome of the radial artery transducer
(B) coarctation of the aorta
(C) peripheral vascular constriction produced by sympathetic stimulation
(D) physiologic amplification of the wave form from the aorta to the radial artery
(E) too high a frequency response in the catheter-transducer system
A 55-kg, 70-year-old woman with mild chronic renal failure is unresponsive 20 hours after an uneventful coronary artery bypass grafting procedure. Anesthetic drugs included fentanyl 3000 mcg, diazepam 35 mg, and pancuronium 20 mg. Which of the following is the most appropriate next step in management?
A 20-kg, 6-year-old boy is undergoing strabismus surgery under anesthesia with sevoflurane, nitrous oxide, and oxygen. The heart rate suddenly decreases from 85 to 40 bpm. Which of the following is the most appropriate first step in management?
A previously healthy 28-year-old woman scheduled for laparoscopic tubal ligation becomes, agitated and refuses to undergo the procedure after being brought to the operating room. This behavior most likely resulted from preoperative administration of
A 26-year-old woman comes to a pain clinic because of pain, swelling and limitation of motion in the right knee for six months following a blow to the knee. Findings on knee arthroscopy and leg roentgenograms are normal. The best trial of therapy is
(A) right paravertebral lumbar sympathetic nerve block
(B) epidural administration of a steroid
(C) intrathecal administration of an opioid
(D) tricyclic antidepressants for one month
(E) a nonsteroidal anti-inflammatory drug for five days
Following maternal epidural injection, fetal exposure to chloroprocaine is lower than fetal exposure to bupivacaine for which of the following reasons?
(A) Chloroprocaine is metabolized by plasma cholinesterase
(B) Chloroprocaine is more protein bound
(C) Chloroprocaine is not readily absorbed from the epidural space
(D) The ionized fraction of chloroprocaine in the fetal circulation is smaller
(E) The pKa of chloroprocaine is less than that of bupivacaine
In a 5-kg child, the end-tidal carbon dioxide tension is 35 mmHg during spontaneous ventilation through a Mapleson D system. Which single change is most likely to increase this value?