For any given FiO2 and PaCO2, the PaO2 is lower in a healthy paralyzed patient anesthetized with isoflurane than in the same patient unanesthetized and breathing spontaneously. The primary cause of this difference is
(A) controlled ventilation
(B) increased airway resistance
(C) inhibition of hypoxic pulmonary vasoconstriction
An atrioventricular sequential demand pacemaker is placed in a patient who has abnormal atrioventricular conduction. Each of the following statements about this situation is true EXCEPT:
(A) Electrocautery could lead to long pauses in the paced rhythm
(B) Placing a magnet over the generator will convert it to an asynchronous (fixed rate) unit
(C) If complete heart block develops, the paced ventricular rate will be the same as the sinus node rate
(D) An atropine-induced increase in the sinus rate will increase the ventricular rate
(E) During symptomatic tachyarrhythmia, cardioversion would be contraindicated because it would alter the pacemaker's function
Monitoring of a patient with a closed head injury shows the following pressures: Intracranial pressure 30 mmHg, Central venous pressure 5 mmHg, Mean arterial pressure 65 mmHg, Peak airway pressure 25 cmH,0. The cerebral perfusion pressure is
(A) 30 mmHg
(B) 35 mmHg
(C) 40 mmHg
(D) 60 mmHg
(E) 65 mmHg
B
In an adult undergoing laparotomy, which of the following is the most effective means of maintaining body temperature during the first hour of anesthesia?
(A) Increasing ambient temperature
(B) Using a warming blanket
(C) Warming inspired gases
(D) Warming intravenous fluids
(E) Warming irrigating fluids
A
Metoclopramide
(A) decreases gastric acid secretion
(B) decreases gastroesophageal sphincter tone
(C) is contraindicated in patients with Parkinson's disease
(D) is most effective when administered in combination with atropine
(E) requires an intact vagus nerve for gastrointestinal effects
Which of the following statements concerning cerebral blood flow (CBF) during anesthesia is true?
(A) CBF changes minimally when PaC02 increases from 30 to 40 mmHg
(B) CBF changes minimally when P02 decreases from 160 to 100 mmHg
(C) CBF is autoregulated when mean arterial pressure is 40 mmHg
(D) CBF is coupled to cerebral metabolism during isoflurane anesthesia
(E) CBF is unaffected by 1.2% isoflurane at a PaC02 of 40 mmHg
B
In a patient with adult respiratory distress syndrome who is being mechanically ventilated, which of the following findings indicates the most severe disease?
Which of the following would be most likely to result in neonatal depression when administered to a healthy parturient during an uncomplicated labor and vaginal delivery?
(A) Nitrous oxide 60% in oxygen supplemented with halothane 0.5% for 10 minutes before delivery
(B) Ketamine 20 mg intravenously 30 minutes before delivery
(C) Meperidine 100 mg intramuscularly 2 hours before delivery
(D) Thiopental 100 mg intravenously 30 minutes before delivery
(E) Nitrous oxide 60% in oxygen supplemented with enflurane 0.7% for 10 minutes before delivery