Results of two blood gas samples drawn from the same patient, 30 minutes apart, are shown below:

Which of the following is the most likely explanation for these differences?

Prior to performing a multiple-breath U2 washout test, a pulmonary function technologist is unable to zero the H2 gas analyzer. Which of the following may be responsible?

A pulmonary function laboratory routinely tests five subjects as biologic controls.
Acceptable instrument performance over time is indicated when measurements

The following results were obtained from spirometry before and after a bronchodilator administration:

Which of the following is the correct interpretation of these data?

A patient who smokes three packs of cigarettes a day has a DLco Of 45% of predicted. The patient is referred for exercise (stress) testing. Which of the following should a pulmonary function technologist select to evaluate oxygenation?