During right upper lobectomy and one-lung ventilation with a double-lumen endotracheal tube, the PaO2 decreases to 40 mmHg. The PaCO2 is 39 mmHg. Which of the following is most appropriate?
(A) Confirm position of the tube with bronchoscopy
(B) Apply 5 cmH20 continuous positive airway pressure to the nondependent lung
(C) Apply 5 cmH20 positive end-expiratory pressure to the dependent lung
(D) Resume two-lung ventilation
(E) Clamp the pulmonary artery of the nondependent lung
During an operation with cardiopulmonary bypass using a bubble oxygenator, the risk for systemic gas embolization increases when
(A) a filter greater than 20 microns is used in the arterial infusion tubing
(B) gas flow to the oxygenator is decreased below 3 L/min
(C) the operation is a mitral valve replacement
(D) the blood level in the oxygenator reservoir exceeds 1 liter
(E) ventricular fibrillation occurs
C
In a 5-kg child, the end-tidal carbon dioxide tension is 35 mmHg during spontaneous ventilation through a Mapleson D system. Which single change is most likely to increase this value?
For 30 minutes, a patient has been receiving oxygen 2 L, nitrous oxide 2 L, and halothane from an agent-specific vaporizer set at 1%. A mass spectrometer sampling gas from the patient's airway shows an end-tidal halothane concentration of 0.7%. The most likely explanation for this difference is