Answer to Question 1
ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: Under ideal conditions, all gas leaving the O2 source is delivered to the patient. However, in pneumatically or fluidically controlled ventilators, these control circuits often consume gas to power inspiration and expiration. Gas consumption is defined as gas used by the ventilator for operating circuits or valves, which is exhausted into the atmosphere and not delivered to the patient.
Answer to Question 2
ANS: A
A. Correct response: Humidification of the patient's airway is often overlooked during transport. Part of the reason is the difficulty and impracticality of transporting the patient with a humidification system during transport. The logistics and dangers of transporting an electrically powered, position-dependent, water-filled device are exasperating. However, humidification must be provided because delivery of anhydrous medical gases to the tracheobronchial tree can cause tissue damage in less than 30 minutes. A passive humidification device (i.e., a heat-moisture exchanger (HME) or artificial nose) may be used. An HME collects the patient's own respired heat and moisture during expiration, and returns them to the patient's respiratory tract during the ensuing inspiration. HMEs are not as efficient as heated humidification systems, but are particularly suited for patient transport.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.