After inflation of both the tracheal and endobronchial cuffs of a left-sided double-lumen tube, the following are noted on auscultation of the chest: Left lumen clamped --> Breath sounds absent bilaterally; Right lumen clamped --> Breath sounds present on left only; Both lumens open --> Breath sounds present on left only. The most appropriate action is to
(A) decrease the endobronchial cuff volume
(B) decrease the tracheal cuff volume
(C) reinsert the tube, rotating it 180 degrees to the right
(D) suction both lumens
(E) withdraw the tube slightly and repeat the auscultory maneuvers
A patient is undergoing a craniotomy in the sitting position. Mean arterial pressure measures 80 mmHg from a radial artery catheter located 27 cm below the right atrium and a transducer located, zeroed, and calibrated at the level of the right atrium. The circle of Willis is 27 cm above the right atrium. Intracranial pressure is 0 cmH20 and right atrial pressure is 5 cmH20. The cerebral perfusion pressure in mmHg is
(A) 75
(B) 60
(C) 53
(D) 48
(E) 26
B
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
Depression of cerebral oxygen requirements below the level required to create an isoelectric EEG can be achieved by
A 30-year-old man who is breathing spontaneously has a ventilatory pattern of sustained deep inspiration and occasional expiratory gasps during emergence from general anesthesia after posterior fossa craniotomy. Which of the following is the most likely cause?