Spirometer........

 Just like me I'm sure you asking, exactly what is a  spirometer  and it's functions?  I saw one once and didn't even realize what the name of the unit was.  I now know that it has to do with the functions of a patients lungs.  In other words, is can measure the rate at which a person's lungs are functioning, in comparison to a healthy person's lungs.  There are several types of units, that can be obtained, considering the price range and the amenities the units have.