A 19-year-old college student is brought to the emergency department cyanotic and incoherent. Respiratory rate is 48/min, pulse is 140 bpm, and blood pressure is 140/85 mmHg. The only history obtainable is that he was at a party and suddenly felt sick. Cyanosis persists despite administration of pure oxygen by mask. A venous blood sample is chocolate-brown. The action most beneficial to the patient is to
(A) intubate the trachea and control ventilation
(B) perform bronchoscopy to treat foreign body aspiration
(C) obtain a pulmonary ventilation-perfusion scan
(D) administer methylene blue intravenously
(E) administer thiosulfate in normal saline solution intravenously
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
Which of the following is the primary factor regulating normal coronary blood flow?
A 64-year-old, 87-kg woman in good general health is undergoing a right knee arthroplasty while in the supine position with general anesthesia consisting of enflurane 2% and nitrous oxide 50% in oxygen. She is breathing spontaneously through a 7-mm endotracheal tube. During the first 30 minutes of the procedure, the arterial oxygen saturation measured by pulse oximetry decreases from 98% to 92%. The most likely cause of the desaturation is
(A) decreased functional residual capacity
(B) diffusion hypoxia
(C) hypercarbia
(D) increased airway resistance produced by the endotracheal tube
(E) inhibition of hypoxic pulmonary vasoconstriction
A 27-year-old man with a one-month history of quadriplegia at a C6 level is given general anesthesia for cystoscopy. During the cystoscopy, blood pressure suddenly increases to 220/120 mmHg. Further evaluation is most likely to show
During cardiopulmonary bypass, the perfusionist notes that the mixed venous oxygen saturation has decreased from to 55%. Which of the following is the most likely cause?
(A) Administration of a nitroprusside bolus
(B) Administration of a thiopental bolus
(C) Decrease in rectal temperature from 34°C to 28°C
An intubated patient is breathing spontaneously through the T-piece shown in Figure 1. Addition of tubing at A and B as shown in Figure 2 without an increase in minute ventilation will result in
(A) unchanged FiO2 and increased PaCO2
(B) unchanged FiO2 and unchanged PaCO2
(C) increased FiO2 and increased PaCO2
(D) increased FiO2 and unchanged PaCO2
(E) decreased FiO2 and increased PaCO2
C
Two hours after a colon resection, a 60-year-old woman with adult-onset diabetes mellitus is somnolent and has a blood glucose concentration of 612 mg/dl. Which of the following findings are most likely? (Sodium, Osmolality, Intravascular volume)
(A) 127, 280, High
(B) 127, 310, High
(C) 127, 330, Low
(D) 140, 280, Normal
(E) 140, 300, Low
C
Which of the following statements concerning isolated mitral stenosis is true?
(A) Afterload reduction increases cardiac output
(B) Pulmonary artery occlusion pressure overestimates left ventricular filling pressure
(C) Pulmonary hypertension is irreversible
(D) Tachycardia decreases the mitral transvalvular gradient
(E) Thermodilution cardiac output measurements are unreliable