Don’t ignore office spirometry

My PFT Lab has recently been asked by several doctor’s offices and clinics to advise them on the purchase of an office spirometry system. I am not a fan of office spirometry because I think the test quality is often low. Office spirometry is usually performed by poorly trained office staff using poorly maintained equipment and under these conditions quality is going to suffer. Despite my misgivings the reality is that office spirometry is not going away and in fact its use is probably expanding.

There are several good reasons why this is happening. More testing of all kinds is being done at the point of care and there is an increased awareness of standards of care for COPD and Asthma. There is also revenue generation (the websites of several office spirometer manufacturers have downloadable documents showing return on investment and the proper codes to use (ICD9 and CPT) when billing).

I think that we ignore this trend at our own peril and that the proper response should be to reach out and offer assistance in selecting office spirometers and training office staff to perform spirometry instead. Although this will require extra effort with no immediately apparent payback I think this should be done not only because it is the right thing to do for the patient’s sake but also because it will pay dividends in the long run.

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How to HAST

Patients that have problems with oxygenation at sea level are going to have even more problems at higher elevations where the barometric pressure and oxygen partial pressure are lower. During commercial aircraft travel the cabin pressure is required by U.S. Federal regulations to be pressurized to at least 565 mm Hg which is the equivalent of 8000 feet altitude. It has been reported that most airliners are pressurized to an equivalent altitude of between 5000 and 8000 feet but this will depend on both the airplane and the airline in question.

There is a general relationship between a patient’s PaO2 at sea level and their PaO2 at altitude and a variety of studies have developed equations to predict an individual’s PaO2 at altitude using ABG, spirometry, DLCO and exercise SpO2 results. These prediction equations however, have been shown to have poor accuracy when compared to a Hypoxia Altitude Simulation Test (HAST).

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