What can trigger an inaccurate pulmonary function test?

PFT: This test can be highly variable. The quality of the test can depend on several things. The patient performing the test has to really give it a good effort. Many times this is also dependent on the person administering the test, who must be a good instructor. Also the equipment must be calibrated, and functioning well, no air leaks and also the type of equipment may allow for some variability

Commonly poor effort: Pulmonary tests are dependent on the effort of the patient. Without a deep breath and a forceful, sustained blow, the test results are inaccurate. Also use of bronchodilators prior to the test will falsely improve those with obstruction. PFT's require an experienced examiner and a graphic depiction with which to gauge the accuracy of the effort.