Which of the following statements is false regarding ventilation in the assist-control mode?

Question

a. Every breath is supported by the ventila-tor.
b. Usually ensures a minimum safe level of ventilation is given.
c. Assist-control mode is typically applied using the volume control mode.
d. It is usually applied with a backup rate of 5 to 8 breaths/min.

Answer 1

ANS: D
With assist-control mode, every breath is supported by the ventilator. Breaths are patient- or time-triggered to inspiration and may be volume or pressure limited. Inspiration may be volume, pressure, or time cycled to the expiratory phase. Assist-control ventilation typically is delivered as volume-controlled (VC) continuous mandatory ventilation. Suggested initial settings for as-sist-control volume ventilation in the care of adults are listed in Box 48-4. Advantages of as-sist-control volume ventilation include the assurance that a minimum, safe level of ventilation is achieved. Every breath is a volume breath, yet the patient can set his or her own breathing rate. In the event of sedation or apnea, a minimum, safe level of ventilation is guaranteed by the selection of an appropriate backup rate, usually approximately 2 to 4 breaths/min below the patient's assist rate, but not less than the rate necessary to provide a minimum safe level of ventilation (e.g., a backup rate of at least 8 to 10 breaths/min, depending on tidal volume set). Because assist-control ventilation usually provides full ventilatory support, it may result in a lower work of breathing than partial support modes.