A 70-year-old man has a pacemaker set at VOO mode at 70 bpm with temporary atrial and ventricular wires placed prior to separation from cardiopulmonary bypass. Fifteen minutes after separation, he develops atrial fibrillation with a ventricular response of 80 to 100 bpm. Which of the following ECG findings is most likely?
(A) Irregular atrial and ventricular complexes with loss of pacer artifacts
(B) Irregular ventricular complexes with preserved ventricular pacer artifacts at 70 bpm
(C) Occasional pacer artifacts when intrinsic ventricular rate is slower than 70 bpm
(D) Regular ventricular complexes at 70 bpm
(E) Ventricular complexes with preserved atrial and ventricular pacer artifacts at 70 bpm
B
During a craniotomy for a supratentorial tumor, a 28-year-old man receives isoflurane 0.75% in nitrous oxide 70% and oxygen. Ventilation is controlled to maintain PaCO2 at 25 mmHg. Nasopharyngeal temperature is 35.8°C. While the dura mater is open, the surgeon complains that the brain is bulging. The most appropriate management at this time is to
(A) decrease the inspired isoflurane concentration to 0.5%
(B) hyperventilate further to decrease PaCO2 to 20 mmHg
A 70-kg, 20-year-old athlete receives nitrous oxide and oxygen, thiopental, and fentanyl 1.25 mg (25 ml) during a knee reconstruction procedure lasting three hours. Postoperatively, he does not awaken or resume spontaneous breathing for three hours. The most likely explanation for the prolonged effect of fentanyl is
(A) dose-dependent elimination half-life
(B) genetically slow biotransformation
(C) large volume of distribution
(D) presence of an active metabolite in high concentration
(B) abdominal pain secondary to chronic pancreatitis
(C) persistent chest wall pain secondary to intercostal neuralgia following a thoracotomy for trauma
(D) reflex sympathetic dystrophy of the upper extremity with an excellent but transient response to a series of stellate ganglion blocks with local anesthetic
(E) a diabetic patient scheduled for surgical sympathectomy to relieve unilateral lower extremity pain secondary
A 19-year-old woman receives a spinal anesthetic for a repeat cesarean delivery. Two days later she is afebrile but has severe occipital pain that is aggravated by sitting or standing and relieved by lying flat. Associated findings would likely include
A 64-year-old patient with chronic obstructive pulmonary disease sustained fractures of ribs 4 through 8 on the left one hour ago. Examination shows agitation, heart rate of 120 bpm, respiratory rate of 30/min, and blood pressure of 180/100 mmHg. PaO2 is 70 mmHg and PaCO2 is 35 mmHg on room air. Radiographs of the chest show no abnormalities. Which of the following is the most appropriate immediate management?
(A) Continuous epidural analgesia using local anesthetics
(B) Mechanical ventilation
(C) Infusion of midazolam
(D) Patient-controlled analgesia with morphine sulfate
A 50-year-old patient is undergoing craniotomy for clipping of a cerebral aneurysm with isoflurane, nitrous oxide, and fentanyl anesthesia. At the time of aneurysm exposure, the EEG shows burst suppression. Which of the following is the most likely cause?