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: Desirable characteristics of an MO-MA device includes a clear, soft mask capable of making an effective seal with the patient's face; an O2 inlet nipple; a nonrebreathing valve that diverts expired flow away from the rescuer; low-flow resistance; no back leak; and a filter with low-flow resistance that is not adversely affected by humidity or vomitus. Dead space should be considered in pediatric applications. In adults a dead space of less than 200 ml is acceptable.
Answer to Question 2
ANS: A
A. Correct response: Gastric insufflation with the potential sequelae of pulmonary aspiration is a problem whenever ventilation via an unprotected airway is attempted. Using less forceful inspirations, longer inspiratory times, and smaller tidal volumes are effective strategies in limiting gastric insufflation. The application of pressure to the anterior aspect of the cricoid cartilage (i.e., the Sellick maneuver) is another technique to prevent gastric insufflation. The cricoid cartilage completely encircles the upper airway. Therefore this region is the strongest part of the airway. Applying gentle pressure on the anterior neck at the level of the cricoid cartilage will pinch the esophagus between the cervical vertebrae and the cricoid cartilage. This effectively increases the esophageal opening pressure, making the entry of air into the stomach more difficult. In the event that the stomach is already distended, the Sellick maneuver may reduce the chance of vomiting.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A