During a single-breath capnogram, the sharp downstroke and return to baseline that normally oc-curs after the end-tidal point indicates what?

a. Exhalation of mainly dead space gas
b. Inspiration of fresh respiratory gas
c. Exhalation of mixed alveolar and dead space gas
d. Exhalation of mainly alveolar gas

ANS: B
The sharp downstroke and return to baseline that normally occurs after the end-tidal point indi-cates inhalation of fresh gas with 0 CO2.