A 60-kg, 45-year-old woman who takes digoxin for atrial fibrillation receives furosemide 40 mg and mannitol 60 g during resection of a supratentorial meningioma. After initiation of hyperventilation to decrease PaC02 from 35 to 20 mmHg, multifocal premature ventricular contractions are noted on the ECG. The most likely cause is
(A) acute hypokalemia
(B) cerebral ischemia
(C) impending herniation of the brain stem
(D) paradoxical air embolism
(E) surgical manipulation of the meningioma
A
A 37-year-old woman with pregnancy-induced hypertension develops oliguria two hours after cesarean delivery during epidural .anesthesia. Despite infusion of 2000 mL of crystalloid solution, urine output remains 10 mL/hr. Which of the following laboratory findings is most suggestive of acute tubular necrosis?
(A) Blood urea nitrogen level of 30 mg/dL
(B) Serum creatinine level of 1.2 mg/dL
(C) Urinary/plasma osmolality of 1:1
(D) Urinary sodium level of 10 mEq/L
(E) Urinary specific gravity of 1.024
C
Which of the following results in the greatest increase in right-to-left shunting in an infant with cyanotic heart disease?
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
Which of the following statements concerning fetal hemoglobin is true?
(A) It makes up less than 50% of the total hemoglobin in the neonate
(B) It has less affinity for oxygen than adult hemoglobin
(C) It binds with greater affinity to 2,3-DPG than adult hemoglobin
(D) It shifts the oxyhemoglobin dissociation curve to the left
Nine months after sustaining an injury to the left forearm, a 30-year-old woman has diffuse, burning pain on the anterior aspect of the forearm and posterior aspect of the hand and discoloration of the skin in the affected areas. The patient should be informed that
(A) if left untreated, muscle atrophy may develop in the involved limb
(B) if left untreated, the pain will remain well localized
(C) physical therapy is not indicated
(D) the symptoms are directly related to the severity of the initial injury
(E) the symptoms are most likely secondary to underlying peripheral vascular disease