A 30-year-old primiparous woman delivered a healthy infant by cesarean section during uneventful spinal anesthesia with tetracaine 10 mg in 2 ml of 5% dextrose solution. Twelve hours after delivery she has bilateral loss of pain and temperature sensibility, but not touch, below T8 and paralysis of both legs. The most likely cause of this complication is
A 55-year-old man undergoes abdominal perineal resection in the lithotomy position during combined epidural (bupivacaine 0.5%) and isoflurane anesthesia. The epidural catheter is left in place with an infusion of fentanyl 50 jug/hr. Twelve hours after surgery, the patient has left footdrop. Which of the following is the most likely explanation?
(A) Epidural hematoma
(B) Epidural opioid
(C) Inadequate padding of the knee during surgery
(D) Nerve injury from the epidural catheter
(E) Residual effects of the local anesthetic
C
After two hours of anesthesia with halothane 1.2% and oxygen, nitrous oxide 75% is added to the inspired gas mixture. This addition would
(A) increase the alveolar halothane and oxygen concentrations above inspired
(B) increase the alveolar halothane concentration only
(C) cause no change in alveolar gas concentrations compared with inspired
(D) decrease alveolar oxygen concentration compared with inspired
(E) decrease alveolar oxygen and halothane concentrations below inspired
A
Cyanide toxicity from nitroprusside is unlikely in patients with renal dysfunction because
(A) renal excretion of thiosulfate is decreased
(B) metabolic acidosis inactivates cyanide
(C) anemia inhibits breakdown of nitroprusside by oxyhemoglobin
(D) thiocyanate is formed in the liver
(E) the dose of nitroprusside necessary to lower blood pressure is greatly decreased
An 18-month-old child with tetralogy of Fallot is anesthetized with halothane and nitrous oxide. Following intubation, oxygen saturation decreases abruptly from 85% to 45%. The most effective treatment is
Addition of 20 cmH2O positive end-expiratory pressure to a patient receiving controlled mechanical ventilation decreases cardiac output and left ventricular function by