nitrogen washout connect the umbilical to the gas calibration port and select gas calibration gas calibration successful message will appear at the bottom of the screen when the calibration is complete connect the umbilical to the pre-even flow sensor have the patient put his lips tightly around the mouthpiece and put the nose clip on the patient select start and have the patient breathe normally there will be four countdown breaths in the quality control gauge then perform four title breaths the breaths will be seen on the screen have the patient exhale fully at the bottom of the fifth title breath and then inhale maximally have the patient return to normal breathing and select the space bar at the end of the title breath the shutter will switch the patient to 100 oxygen during the test the quality control gauge will show the respiratory rate the accumulated frc the percent of nitrogen and the switching error keep in mind that the switch in should be between plus or minus 250 mils the test will stop automatically when the final n2 percent is at or below 1.5 percent this will also be shown on the qc gauge the scorecard shows which ats criteria were met