A woman with chronic obstructive pulmonary disease is extubated and minimally responsive after isoflurane anesthesia. She is receiving oxygen 6 L/min through a face mask. Respirations are 10/min, PaO2 is 68 mmHg, PaCO2 is 54 mmHg, and pH is 7.28. The most likely cause of the respiratory acidemia is
(A) blunted sensitivity to low pH in the medullary respiratory center
(B) chronic carbon dioxide retention
(C) decreased lung volume from supine positioning
(D) depression of carotid body chemoreceptors by halothane
(E) suppression of hypoxic ventilatory drive by supplemental oxygen
An 86-kg, 67-year-old man is undergoing a second coronary artery bypass operation. Five minutes after administration of protamine, blood pressure is 69/40 mmHg, pulmonary artery pressure is 65/42 mmHg, and the cardiac output measured by thermodilution is 2.3 L/min. Which of the following is the most likely cause of these findings?
(A) Allergy to fish
(B) Increased plasma thromboxane concentration
(C) Increased plasma histamine concentration
(D) Insulin-dependent diabetes mellitus
(E) IgE antibodies to protamine
B
Which the following findings is most hazardous in premature infants?
(A) Hematocrit of 55%
(B) Rectal temperature of 35 degrees C
(C) Umbilical arterial blood PO2 of 50 mmHg
(D) Umbilical arterial blood PCO2 of 45 mmHg
(E) Umbilical arterial systolic pressure of 60 mmHg
A 20-year-old man involved in a motor vehicle accident is brought to the operating room for irrigation and debridement of open fractures of the femur and humerus. Cyanosis, decreased breath sounds on the left, increased peak airway pressure, and hypotension are noted after intubation of the trachea. The most likely cause is
An apneic adult is receiving an oxygen flow of 4 L/min through a rigid bronchoscope. After five minutes of apnea, which of the following findings is most likely?