A 65-kg 70-year-old man in the PACU is breathing spontaneously at 20/min through an endotracheal tube connected to a T-piece with a fresh gas flow of 5 L/min. He has a tidal volume of 350 mL and an FiO2 of 0.5. SpO2 decreases from 98% to 84% over one hour, then improves to 92% with an FiO2 of 1.0. Which of the following is the most likely cause of the hypoxemia?
(A) Decreased functional residual capacity
(B) Increased dead space ventilation
(C) Inhibition of hypoxic pulmonary vasoconstriction
An 18-year-old woman has knee pain during arthroscopy performed with femoral and sciatic nerve blocks for repair of a torn medial meniscus. The most appropriate management is addition of which of the following nerve blocks?
A 62-year-old patient undergoes resection of a descending thoracic aneurysm under anesthesia with morphine, nitrous oxide, oxygen, and pancuronium. In spite of normal somatosensory evoked potentials (SSEP) during the procedure, the patient has paraplegia postoperatively. The factor most likely responsible for failure to note the deficit intraoperatively is
(A) the effect of nitrous oxide on SSEP
(B) the effect of morphine on SSEP
(C) failure to test motor pathways
(D) hyperventilation to a PaC02 of 30 mmHg
(E) unintentional hypothermia to 34°C
C
A 72-year-old man has had residual hemiparesis since having a cerebrovascular accident three years ago. Compared with the response of the unaffected limbs to nondepolarizing muscle relaxants, the hemiparetic limbs will show
(A) the same response
(B) greater depression of tetanus
(C) greater twitch depression
(D) less twitch depression
(E) less post-tetanic facilitation
D
A 65-kg man is scheduled for wrist surgery with intravenous regional anesthesia with 0.5% lidocaine 50 ml. Which of the following statements is true?
(A) This anesthetic is contraindicated if the patient has sickle cell disease
(B) Mottling of the skin after injection dictates abandonment of the technique
(C) Tourniquet discomfort is an indication to inject more local anesthetic
(D) Bupivacaine 0.5% could be substituted to prolong anesthesia
(E) Epinephrine (1:400,000) should be added to prolong anesthesia