Naughty or Nice? New Guidelines for Exhaled Nitric Oxide Will Lead to Better Asthma Control
By Dr. Larry Chiaramonte
The American Thoracic Society [ATS] has now issued guidelines for the use of something called fractional exhaled nitric oxide [FEno] in assessing the severity of asthma. This is a welcome development for a technology that has already allowed us to calibrate more precisely the dosages of asthma control medicines, as in this study of asthma among pregnant women.
FEno is a bio-marker for asthmatic inflammation. That is, the more of this gas in exhaled breath, the greater the degree of asthmatic activity in the lungs. Other methods of calculating asthma control such as peak flows and lung function are imprecise because results depend on patient effort as well as lung capacity. More accurate methods, such as counting the eosinophils in sputum, require special equipment and expertise, and are a particular drag with children because dragging a specimen out of them is very unpleasant for both patient and doctor. The technology of measuring FEno has been around for a long time, but it was prohibitively expensive for the typical medical practice. In the last few years, however, the development of a small, handheld device has makes it feasible to quickly measure the gas and show the results to the patient.
I have used these devices, called NIOX MINO. They work. They are particularly useful when patients tell me they have been taking their medication conscientiously and can’t understand why they still ended up in the emergency room. The numbers don’t lie, although I’m afraid patients do, and we can get the numbers on the spot. This is why some people call the NIOX MINO the “naughty or nice machine.” The company Aerocrine, which makes them, has compiled a particularly powerful case history, which we repeat in our book. It tells of a teenager from a very troubled home who swore up and down that he had been taking his meds, the pharmacist’s records showed that his prescriptions had been filled regularly, and yet his asthma became so bad that the final specialist who saw him was on the verge of reporting him to the state as in danger of imminent death. This specialist gave him the FEno test, which showed that inflammation was raging. FEno was at 70 parts per billion. The new guidelines define the threshold for uncontrolled asthma at 25 ppb. Faced with this evidence, the boy confessed that he had been stashing his medication under his bed. He had done this because his sister was confined to a wheelchair and his asthma helped him compete for the attention of the single mother. After taking the medication regularly (and a program of family therapy) his FEno levels came down below 20 ppb.