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RES 131. Pulmonary Functions. Good Start of Test. Start of test must be quick and forceful No excessive hesitation Best evaluated using the Flow-Volume tracing No excessive back extrapolated volume. Good Start of Test. No Coughing. Especially during the first 1 second of the maneuver
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RES 131 Pulmonary Functions
Good Start of Test • Start of test must be quick and forceful • No excessive hesitation • Best evaluated using the Flow-Volume tracing • No excessive back extrapolated volume
No Coughing • Especially during the first 1 second of the maneuver • Best if no coughing present during maneuver, however: • Some patients cough near the end of each test, if present then document
No Variable Flow Flow rate should be maximal and consistent throughout testing Volume-Time and Flow-Volume tracings should be smooth
No Early Termination of Effort • Best if maneuver lasts at least six (6) seconds • Less than six seconds acceptable if a plateau of al least one (1) second is present • If patient is unable to meet the above criteria, document in comment section
Reproducibility • Spirometry induced bronchospasm • Each effort gets worse • Patient eventually reaches a plateau, however they may be too short of breath to continue. • Which effort to report? • Best effort unless pre and post bronchodilator study, then report the worst effort.
Temperature Correction • Charles law states that the volume occupied by a given quantity of gas is directly related to temperature • Body temperature gas is exhaled into a room temperature spirometer, therefore the volume decreases • Temperature correction allows us to know the volume of gas as it was in the body
Temperature Correction • Charles law states that the volume occupied by a given quantity of gas is directly related to temperature • Body temperature gas is exhaled into a room temperature spirometer, therefore the volume decreases • Temperature correction allows us to know the volume of gas as it was in the body
Temperature Correction • The volume measured by the spirometer is reflected at ATPS (atmospheric temperature, pressure, saturated) • It must be corrected to BTPS (body temperature, pressure, saturated)
Temperature Correction • Formula for calculation of temperature correction factor
Temperature Correction • Conversion factor is multiplied by the ATPS volume to find the BTPS volume.
Back Extrapolation • Extrapolated Volume may not exceed 5% of the FVC