In a spring-loaded bellows volume-delivery device, the amount of pressure is determined by the:

a. location of the bellows.
b. volume setting on the ventilator.
c. tightness of the spring.
d. electrical power provided to the spring.

ANS: C
In a spring-loaded bellows model, an adjustable spring atop a bellows applies a force per unit ar-ea, or pressure (P = Force/area). Tightening of the spring creates greater force and therefore greater pressure. The bellows contains pre-blended gas (air and oxygen), which is administered to the patient.