Clinical pulmonary function testing using spirometry is an essential tool for the diagnosis and management of cystic fibrosis, but new research and new technology advancements suggest home spirometry could soon become an efficient alternative. 

By Phyllis Hanlon

Children inherit a number of traits from their parents, including eye and hair color, body type, personality, and predisposition to certain medical conditions, one of which could be cystic fibrosis (CF). According to the Cystic Fibrosis Foundation, 1,000 new cases of CF are diagnosed every year, and more than 70% are identified by the time a child turns 2 years old.1

This disease, caused by gene mutation of the protein that regulates sweat, digestive fluids, and mucus, affects the lungs and digestive systems of approximately 30,000 children and adults in the United States, and 70,000 people worldwide.1 In the 1950s, individuals could expect a limited lifespan, perhaps long enough to finish elementary school. But the life expectancy for patients with CF has improved in recent years. Today, many people with CF can live beyond their 40th birthday, with continued research advancements occurring every year.

Identify and Monitor

Rick Carter, PhD, MBA, a professor in exercise sciences physiology at Lamar University in Beaumont, Tex, cited spirometry as one of the initial ways to establish a CF diagnosis. Furthermore, as a tracking tool, spirometry enables clinicians to follow the patient from an early age all the way through adulthood, monitoring pulmonary function in an effort to manage the disease and avoid the need for a lung transplant. “Once you’ve done x-rays and a sweat test, you use spirometry to follow the course of the disease, ” he said, noting that obtaining a baseline takes 30 minutes, on average.

Carter explained that the test establishes individual norms, which form the basis for comparison data as the patient ages. “When a patient matures in stature, we watch for decline. Hopefully, the lungs are growing,” he said. By tracking the disease, clinicians can better determine whether changes should be made to current medication interventions. “Doctors may change a prescription after a certain amount of time to get the results they want,” Carter noted.

According to Pamela Zeitlin, MD, PhD, a professor in the pediatric pulmonary division, director of pulmonary medicine, and co-director of the Pediatric Cystic Fibrosis Center at Johns Hopkins Hospital in Baltimore, the procedure is quite simple. The patient takes a deep breath in and then blows hard for as long as they can, repeating the process two or three times until the technician gets a consistent reading. The spirometer measures a number of diagnostics, including forced expiratory volume in the first second (FEV1), which measures the amount of air volume that can be forcefully exhaled from the lungs in 1 second.

The patient’s FEV1 results are compared to an accepted average score relative to their gender, age, and other factors, and are classified in one of five groups: Normal: 80% to 100%; Mild: 60% to 79%; Moderate: 40% to 59%; Severe: 35% to 40%; and Very Severe: <35%. The device also measures forced expiratory flow (FEF25%-75%), forced vital capacity (FVC), and the ratio between FEV1 and FVC, which determines the severity of the lung disease.

The numbers from spirometry readings help clinicians evaluate where a patient lies in relation to lung function and CF, explained Zeitlin. “If a patient is doing worse than the average, you would look to see if anything can be added to the regimen to increase the median FEV,” she said. “We are looking for good flow volume loop. We use the number to determine the health of the lungs, and use over time helps us see if an infection is causing the lung function to decrease.” Typically, a change in results greater than 10% is cause for concern, while a change greater than 20% is considered an exacerbation and requires an aggressive approach.


Although spirometry serves as a valuable measuring tool and is relatively simple to do, obtaining accurate results can be challenging. The health care professional administering the test must understand the criteria for an acceptable test and must pay close attention to the patient. “The patient has to understand the instructions and must make an effort to exhale forcefully for at least 6 seconds,” explained Carter. “And the technician has to be a good coach. Based on a patient’s age, cognitive status, and illness, challenges may occur. The technician should be well trained to figure out how to elicit a good response. When the testing is done, there should be at least two to three good results.”

When the patient fails to produce adequate results through spirometry, the clinician needs to play detective. “You have to figure out what is going on, why is the patient not following directions,” Carter asserted. “You have to give pointers, get continual feedback, observe, and figure out what’s limiting them.”

Respiratory therapists need to approach each patient situation with zest, reported Terri Sexton, RPFT, RCP, lead technician in the pulmonary diagnostic lab at Santa Clara Valley Medical Center in San Jose, Calif. “You have to be forceful when teaching the patient how to use the device. Everybody should be able to peak, unless they have vocal chord paralysis or some other compromising condition,” she said. “Show some enthusiasm when you tell the patient to blow.”

Getting children to cooperate during spirometry may require creative thinking at times. Mark Patterson, RRT, manages the pediatric pulmonary function lab at the Cleveland Clinic. Patterson pointed out that, unlike an x-ray where the patient sits still, spirometry might allow the patient to move and skew results. “Some doctors think that if a child is 14, he’ll do a good job, but it all depends on how health-smart the kid is,” he said.

One technique seems to work with children of all ages: cartoons. “Animation graphics are good for kids from 4 to 8 years old who might have difficulty with the technology,” Patterson said. “They can view 10 different cartoons where characters are blowing out candles. This gives incentive for the kids.” The animation is based on time so the young patient knows how many more candles they need to blow out before the time expires. This technique works so effectively that Patterson noted, “We literally have to push the kids out of here, they like the machine so much.”

Patterson also cited comfort level as one of the key factors for clinicians working with youngsters. “You have to be comfortable working with children since you have to motivate and educate them,” he said. “We want to do a good job and give the physician results that comply with criteria from the American Thoracic Society.”

Precautions and Options

For the most part, spirometry has no downsides, although appropriate precautions should always be observed. Children with CF should always be tested in different rooms, according to Patterson. “They might have a bug like Burkholderia cepacia,” he said, explaining that this infection presents as one of 17 different species of bacteria found in the natural environment. “Patients with CF pick up infections easily so you also need to sterilize the machine.”

Cost may be another stumbling block, albeit a minor one. “Tests at a clinic involved with CF are the best way to measure lung function. It costs a few hundred dollars, but it’s better than the cost of hospitalization,” Patterson explained. “If a child gets pneumonia and has to be hospitalized, the parent might have to pay a bit out of pocket.”

Over time, spirometry instruments have been improved, according to Carter, noting that standards have been refined and the normative databases are getting better. “There have been continued improvements in the technology and in the criteria for better training so you get the best results,” he said. However, he pointed out that in cases where spirometry is not feasible, oscillometry makes a good alternative. This device measures airway resistance without any coaching or active involvement on the part of the patient. Patients breathe passively for 20 seconds with their mouths on the device and a loudspeaker bounces the airwaves back. “This works with the normal tidal breathing. There is no forced breathing, so it’s useful in kids,” Carter said.

Jeanne Barrett, a staunch supporter of spirometry, is the president of, an online health community she founded in 1996 in an attempt to link patients and caregivers and provide support and information. Barrett firmly believes that home monitoring of pulmonary function is best for the patient, citing the increased chance of cross-contamination in a clinic or doctor’s office. She emphasized that physicians must routinely monitor patients, but using a home spirometer can help patients personally monitor their conditions. “If they find the numbers are good, they become motivated to keep doing what they are doing,” she said.

Barrett also pointed out the convenience of home spirometry for patients who live great distances from their clinics and research facilities where clinical trials are held. Moreover, patients are receptive to the idea of home spirometry, according to a survey conducted by Medrise, a medical device marketplace that serves the CF community. More than 90% of respondents found the idea of tracking pulmonary function from home appealing.2

While personal spirometry has been used for quite some time, Carter noted that compliance and accuracy of home monitoring might affect results and effective intervention. Many current models hold data for 30 to 45 days, and a nurse or doctor reviews the results when the patient comes to the office. “However, I doubt if [the results] will be accurate, but at least they’ll hopefully be consistent. If they are off by 10% for the whole 30 days, you’ll still see trends. No one is using this for an exact figure,” he said. “And sometimes people take it easy or cheat.”

But more accurate home spirometry may be available in the not too distant future. In recent years, advancements have introduced a variety of devices, including an electronic model; a spiropet or windmill type, which is portable and measures forced vital capacity; a tilt-compensated device that allows the patient to be monitored while in different positions; and, more recently, Internet-based spirometers.

Clinical Trials

A current study out of Johns Hopkins University in Baltimore holds promise for more efficient home monitoring systems.3 Known as the Early Intervention in Cystic Fibrosis Exacerbation (eICE), the clinical trial is supported by the National Institutes of Health and the Cystic Fibrosis Foundation. The end goal of the trial, co-led by Noah Lechtzin, MD, MHS, associate professor of medicine and associate director of the adult cystic fibrosis program at Johns Hopkins, and Christopher Hooper Goss, MD, MS, FCCP, professor in the division of pulmonary and critical care medicine at the University of Washington in Seattle, is to show that by using home spirometry, clinicians can preserve health and prevent decline in lung function.

“We set up inclusion criteria that mimic current CF care and are accepting a broad spectrum of patients 14 and older,” Lechtzin said, noting that patients with an FEV1 of less than 25% predicted or with severe symptoms will not be enrolled. The study began enrolling patients in fall 2011 and will complete enrollment in spring 2014.3 Currently, 185 subjects have been enrolled, with a target of 320.3

The Johns Hopkins eICE clinical trial is a follow-up to a small pilot study of 35 adult patients who used a handheld spirometer twice daily.4 The purpose of the pilot study was to assess patients’ willingness to participate and to measure the results of home spirometry against those obtained in clinical settings. While the outcomes were positive on both counts, there were some shortcomings. “The device couldn’t store much information, only about a month’s worth,” Lechtzin said. “And patients couldn’t transmit information electronically. They had to bring the device into the office and they kept a paper diary.”

A second study followed in which five adult and five pediatric subjects were given a Jaeger AM2 monitor—a home spirometer and electronic diary (eDiary) manufactured by ERT. “At the end of the study, we came up with criteria, evaluated the data, and it looked as though by using spirometry and an objective scale, we could pick up problems earlier,” Lechtzin said. “This brought us to the current study.”

Despite being only in the recruiting phase, Lechtzin foresees few challenges with the Johns Hopkins 12-month clinical trial once it begins. There is no device training involved—these patients have been using spirometry for years, he pointed out—and compliance should not be an issue since CF centers are aware of the study.

Advances resulting from medical research continue to lengthen the life span of those with cystic fibrosis. Currently, the standard of care involves identifying and monitoring the disease in an effort to preserve lung function and maintain quality of life. But Carter predicts that cystic fibrosis treatment of the future will look much different than it does now. “We’ll talk about end of lung life. Transplants will be the last option. Monitoring should use spirometry all the way through treatment,” he said.


Phyllis Hanlon is a contributing writer for RT. For further information, contact [email protected].


  1. The Cystic Fibrosis Foundation. Accessed from
  2. Barnett, J. Personal Spirometry and the Cystic Fibrosis Patient. Accessed from
  3. Early Intervention in Cystic Fibrosis Exacerbation (eICE). Accessed from
  4. Lechtzin, N. Patients Feel at home with Spirometry. Advance for Respiratory Care and Sleep Medicine. 2011. 20:7. Accessed from