Spiriva® HandiHaler® (tiotropium bromide inhalation powder) has a maximum duration
of action
of about 36 hours. To be safe, you would want to be off the
medicine for 48 to 72 hours before the spirometry. It would have been preferable, but not mandatory to do the pulmonary function tests (PFTs) at the time the diagnosis of chronic lung disease was made especially if the diagnosis was unequivocal. The other important question would be, “Why 3 CT scans, presumably of your lungs, in 16 months?