Each of the following is associated with an increased alveolar-arterial oxygen tension difference EXCEPT
(A) advanced age
(B) atelectasis
(C) decreased cardiac output
(D) decreased Fl02
(E) right-to-left intracardiac shunt
D
A 70-year-old patient is shivering and has chest pain in the PACU following a cholecystectomy. Heart rate is 120 bpm, and blood pressure is 220/120 mmHg. SpO2 is 97% at an FiO2 of 0.4. An ECG shows ST-T wave changes, which are not affected by intravenous administration of nitroglycerin. Which of the following is the most appropriate next step?
A moderately obese 38-year-old woman is using patient-controlled morphine analgesia one day after open cholecystectomy. While breathing room air, oxygen saturation is 85%, Pa02 is 48 mmHg, PaC02 is 42 mmHg, and pH is 7.36. In addition to administration of oxygen, the most effective management is to
(A) decrease the dosage of opioids
(B) change to epidural morphine
(C) administer an inhaled bronchodilator
(D) initiate 4 cm of nasal continuous positive airway pressure
(E) initiate incentive spirometry therapy
E
A patient is undergoing exploration of a stab wound to the left side of the neck. On awake laryngoscopy, the left vocal cord is in midposition and the right vocal cord is abducted during inspiration. The most likely cause of these findings is trauma to which of the following structures on the left?
The capnographic tracing is from a 2-month-old infant anesthetized using a pediatric circle system and mask at a fresh gas flow of 4 L/min. The sampling port is in the elbow connector. This tracing indicates
(A) adequate alveolar ventilation
(B) exhausted soda lime
(C) expired halothane concentrations representative of alveolar concentrations
A 40-year-old woman is undergoing a posterior fossa craniotomy in the sitting position for clipping of a basilar artery aneurysm. Nitroprusside is being used to maintain mean arterial pressure at 50 mmHg, measured at head level. During dissection, over the course of one minute, the mean blood pressure decreases to 30 mmHg. Simultaneously, end-tidal carbon dioxide and pulmonary artery pressures decrease and heart rate increases. The most likely cause of these changes is
(A) progressive hypoxemia
(B) nitroprusside bolus
(C) junctional rhythm
(D) brain stem manipulation
(E) venous air embolism
B
The concentration effect is greater with nitrous oxide than with the volatile anesthetics because nitrous oxide
(A) has a lower blood-gas partition coefficient
(B) has less effect on cardiac output (0 has lower lipid solubility
(D) is affected less by ventilation-perfusion mismatch