Patients Feel at Home With Spirometry


Vol. 20 • Issue 11 • Page 25

Pulmonary Function Testing

S.P. is a woman in her 40s with cystic fibrosis who takes good care of herself and has always wanted to stay on top of the latest therapies.

In 2006, not long after two landmark articles were published demonstrating the benefits of nebulized hypertonic saline for CF patients, her physician prescribed hypertonic saline for her to inhale.1,2 She used it regularly for several months but could not appreciate any dramatic change in her respiratory symptoms. Given the large number of medications she was already taking on a daily basis, S.P. came to the CF clinic and told her doctor about her ambivalence toward continuing to use hypertonic saline.

It just so happened that over this same period of time S.P. was taking part in a small pilot study designed to evaluate the utility of home spirometry for individuals with CF. For this study, she used a small electronic spirometer and measured her FEV1 twice daily. The study’s investigators collected and analyzed the information stored in the device every 30 days. S.P.’s doctor had the opportunity to review a graph of S.P.’s home spirometry results and was struck by a dramatic improvement in her FEV1 that occurred abruptly and remained improved for the remainder of the month’s readings. (See Figure, page 26).

S.P.’s doctor showed the impressive spirometry numbers to her and asked if anything had happened at the time of her FEV1 improvement. S.P. looked back at her diary and discovered that her lung function improvement corresponded to the time she started using hypertonic saline. This was enough information to convince S.P. that hypertonic saline was helping her, and she has continued using it to this day.

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Pulmonary function testing with spirometry is a standard component in the face-to-face evaluation and management of CF patients. FEV1 is easy to measure, is reproducible, and has been shown to be an excellent predictor of morbidity and mortality in CF. CF patients experience intermittent exacerbations of their disease. Measurement of FEV1 is an important aspect of detecting exacerbations and in assessing response to therapy.

In our adult CF program, patients call a nurse phone line if they are having an increase in pulmonary symptoms. The CF nurses are adept at triaging these calls and determining if someone needs to be seen. Sometimes treatment with oral antibiotics is initiated over the phone just based on a patient’s symptoms. While this approach works reasonably well, it may lead to both over and under treatment. Additionally, since it relies on patients calling when they become concerned about their symptoms, it may allow for subtle declines in their condition to go unnoticed.

Several years ago, one of the CF nurses began having patients blow into their telephone in order to evaluate if they were having bronchospasm. She would approach me and say, “So and so sounds tight; I think we need to treat them with ..” When I heard about this unusual approach, I realized we needed more objective measures of pulmonary function for outpatients with CF.

We conducted a pilot study to determine if patients would be willing to measure spirometry at home and if the measurements were accurate. We recruited 35 adults with CF and followed them for six months. We found participants were willing and able to measure spirometry on 90 percent of the expected days and that the measurements were highly correlated with values obtained in the pulmonary function lab. In one out of five patients we were able to detect changes in FEV1 that corresponded to the initiation or cessation of a medication such as hypertonic saline or inhaled tobramycin. Home spirometry also appeared to be useful for tracking response to antibiotics for exacerbations. The results of this pilot study were presented at the North American Cystic Fibrosis Conference in Anaheim, Calif., in 2007.3

While results of this small study were encouraging, they raised important questions. Adolescents are a particularly difficult patient group. Teenagers have many demands on their time, and their health is not always their top priority. Treatment adherence is challenging, and it was unknown whether this group would be willing to measure home spirometry.

We also realized that better technology for home spirometry should be used. The original device could only store a month of data at a time, and there was no way for patients to get data to physicians or investigators without delivering the device in person.

We conducted another pilot study to address these concerns. This one included people with CF age 14 and older and used a device that could transmit data via telephone modem. We studied 10 subjects, half of whom were 14 to 17 years old. We asked subjects to send their data to us once a week.4 We found that patients were willing to use the devices, and the data transmission worked well. We used home spirometry data to identify pulmonary exacerbations before patients developed symptoms.

When we compared patients’ use of antibiotics before and during the study period, we found they used slightly less antibiotics but had slightly better lung function. While it’s speculation, it may be that patients gained insight into their health through the use of home spirometry and were able to take steps to maintain their health through better medication adherence and better adherence with airway clearance techniques.

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Home monitoring has become essential for the management of such diseases as diabetes, where patients are expected to monitor blood sugars multiple times per day and adjust insulin dosing accordingly.5 Home monitoring of blood pressure has been shown to provide more accurate diagnosis of hypertension and allows for better management.6 In lung transplantation, home monitoring of lung function is used to detect signs of rejection.7 Our pilot data suggests that home spirometry is acceptable to patients and can provide accurate information about lung function.

We do not yet know whether use of home spirometry and home symptom monitoring can lead to better clinical outcomes. We are collaborating with Christopher Goss, MD, MS, FCCP, and colleagues at the University of Washington, Seattle, to conduct a randomized clinical trial evaluating home monitoring, with funding from the Cystic Fibrosis Foundation and the National Institutes of Health. Participants, adolescents and adults with CF, are randomized to one of two arms:

1. home spirometry and home monitoring of symptoms using the Cystic Fibrosis Respiratory Symptom Diary8

2. standard care.

By studying a larger group of patients, with a more rigorous study design, we hope to determine if use of home monitoring can lead to earlier detection of respiratory problems, earlier treatment, and better health over the long run. Study details can be found on the clinicaltrials.gov website.

Technology has advanced to the point where small electronic spirometers are reliable and affordable. Additionally, they can readily interface with computers and mobile phones, allowing for rapid communication between CF patients and their care centers. Wider use of these devices should allow CF patients and their physicians to more accurately track their health and make adjustments to treatments.

The expected life sup for individuals with CF has improved from less than five years in the 1950s to approximately 37 years now.9 Home spirometry hopefully will allow for further improvements in care, which may translate to more years of good health. n

Noah Lechtzin is an assistant professor of medicine in the division of pulmonary and critical care medicine at the Johns Hopkins University School of Medicine, Baltimore. He is the associate director of the Adult Cystic Fibrosis program at Johns Hopkins.