In both the helium dilution test and nitrogen washout functional residual capacity (FRC) deter-minations, at what point should the patient normally be connected to the system to begin the test?

a. Resting expiration
b. Full forced inspiration
c. Resting inspiration
d. Full forced expiration

ANS: A
The valve is turned to connect the patient to the breathing circuit usually at the resting expiratory level of the FRC.