Educating patients in technique and ensuring that they understand the importance of following their course of treatment result in improved adherence.

In patients with pulmonary disorders, periodic assessment and monitoring of symptoms and signs, lung function, quality of life, frequency of exacerbations, drug therapy, and patient satisfaction with care are necessary to ensure that the goals of management are being met. Pulmonary function tests (PFTs) are one of the most important means of performing periodic assessment and monitoring.

More than 30 million US residents suffer from chronic obstructive pulmonary disease (COPD) and asthma, and most are cared for by internists, family practitioners, and pediatricians.¹ Recent management guidelines^2-4 for asthma and COPD recommend regular use of PFTs for the diagnosis and management of these disorders. Because of the availability of easy-to-use spirometers, an increasing number of clinicians are performing PFTs in their offices. If more detailed PFTs are needed, various tests are available for more thorough evaluation of patients with respiratory disorders.

Spirometry
A spirometer measures lung volumes in order to determine spirometric values, including peak expiratory flow rate (PEFR), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, and forced expiratory flow, midexpiratory phase.

The most important spirometric measurements are the FVC, FEV1, and FEV1/FVC. To measure FVC, the patient inhales forcefully and maximally, then exhales as rapidly and as completely as possible. Normal lungs can usually empty more than 80% of air volume in 6 seconds or less.⁵ The FEV1 is the volume of air exhaled in the first second of the FVC maneuver. Some portable spirometers replace FVC with FEV6 for greater patient and tester ease.⁵ The 6-second maneuver incorporates a standard time frame to decrease variability and the risk of complications. This type of spirometer, however, must be calibrated for temperature and water vapor, and relative humidity.

Airflow obstruction is indicated by reduced FEV1 and FEV1/FVC values. Significant reversibility is indicated by an increase of more than 12% and 200 mL in FEV1 after inhalation of a short-acting bronchodilator.⁶ A reduced FEV1/FVC (less than 65%) indicates obstruction, whereas a reduced FVC with a normal FEV1/FVC suggests a restrictive pattern.⁶ Typically, asthma is associated with an obstructive impairment that is reversible. In general, an improvement is expected in either FEV1 or FVC after acute administration of a short-acting bronchodilator. The absence of a bronchodilator response does not necessarily exclude a diagnosis of asthma, however.

Spirometry is a powerful tool that can be used to detect, follow, and manage patients with asthma and other lung disorders. Technological advances have made spirometry much more reliable than it once was, as well as relatively simple to incorporate into a routine office visit. The National Lung Health Education Program recommends the widespread use of office spirometry for diagnosis, for assessment of symptom severity, and for monitoring the effectiveness of treatment in patients with known or suspected chronic lung disease.⁷

Interpreting spirometry results can sometimes be challenging because the quality of the test depends largely on patient effort and cooperation, as well as on the interpreter’s experience and knowledge of appropriate reference values.

Peak Flow Measurement
PEFR is a simple, quantitative measure of airway obstruction. Daily monitoring of PEFR can be used to detect worsening lung function in the absence of symptoms, assess variations in lung function throughout the day, identify triggers, make appropriate medication decisions, and monitor the response to therapy. A patient can take his or her own PEFR measurements at home, enter the information in a daily diary, and then share the information with the clinician. According to the National Asthma Education and Prevention Program Expert Panel,² clinicians should consider home peak-flow monitoring for patients more than 5 years old who have moderate-to-severe asthma. Spirometry should be performed in the clinician’s office for patients 45 or more years old who are current or former smokers, for patients who have a prolonged or progressive cough or sputum production, and for those who have a history of exposure to lung irritants.^3,4,8

Good PFT Technique
RTs and other care providers can work with patients to ensure that PF testing is done using correct, reproducible techniques. This is particularly important in the emergency department, where it may be necessary to obtain reliable results quickly.

The American Academy of Family Practitioners recently published excellent guidelines⁹ for performing accurate, reproducible spirometry tests (although it may not always be possible to take some of these steps in the emergency department setting). The patient should stop taking bronchodilators 6 to 8 hours prior to testing. He or she should loosen any restrictive clothing and remove loose dentures, candy, or gum. The tester should ensure accurate input of the patient’s identification number, height, weight, sex, age, and race.

The patient may sit or stand, but the position must be consistent and recorded. The use of nose clips is optional, but recommended. The tester should explain the procedure carefully and demonstrate how it is done. Coaching is critical. The patient must be told to blast out the air (not just blow) and to keep going as long, as hard, and as completely as possible, for at least 6 seconds (or for at least 2 seconds in children).

The tester should watch the patient inhale maximally and blast out completely, with the mouth and teeth firmly sealed around the mouthpiece, and should watch or listen for the incentive. If the test is unacceptable, the tester should identify the reason(s) and explain how to correct the technique. At least three acceptable and two reproducible tests should be obtained. If the test results are below normal, the tester should consider administering a bronchodilator according to office protocol and retesting 10 to 15 minutes later.

It is important to be able to recognize when spirometric measurements are unsatisfactory. According to the American Thoracic Society,⁶ a spirometric effort should be considered invalid if any of the following occur:

• a very hesitant or broken expiration at the beginning of the test (or an extrapolated volume of more than 5% of FVC or 0.1 L, whichever is greater);
• coughing during the first second of the test or coughing that interferes with measurement after the first second (coughing at the end of the FVC maneuver does not affect the FEV1 measurement);
• expiration that stops after less than 6 seconds (expiration times of more than 6 seconds are needed for patients with obstructed airways);
• a blocked mouthpiece (for example, the tongue or false teeth of the patient slipping in front of the mouthpiece);
• glottis closure (Valsalva maneuver), indicated by vocal sounds, rumbling in the throat, and flow-volume curves with vertical jagged lines; or
• a leak, with the patient’s lips losing their seal around the mouthpiece.

Improving Adherence
Without specific recommendations, patients may adjust or stop medications on their own. It may be difficult for patients to follow a prescribed course of treatment unless written instructions are provided for patients and families to follow. Three elements of the clinical encounter have been identified by patients as important in the effective management of disease.¹⁰ These are communicating with the patient and family in such a way as to make learning optimal, providing an adequate therapeutic regimen, and delivering core messages (the basic information needed for patients to understand and act on the regimen prescribed). An example of a core message is the importance of daily peak flow monitoring.

As part of the respiratory educational effort, each patient should be given an action plan that outlines the management program.¹¹ The action plan should be easy to follow, should be consistent with the patient’s personal goals and daily activities, should outline the circumstances that will change medication requirements, and should be one that the patient and family agree to follow, once the risks and benefits have been discussed.

The action plan should include guidelines to follow when peak-flow measurements decline and/or symptoms worsen and a diary for recording PEFR measurements. The plan should also include instructions on when to call the clinician’s office and when to seek emergency help. Telephone numbers for the clinician’s office and for urgent care should be written in the booklet. Patients who have experienced rapidly progressive, life-threatening attacks of dyspnea may need to have emergency response systems installed in their homes.

Conclusion
PFTs provide both diagnostic and prognostic information and help in the management of COPD, asthma, and other respiratory diseases. All clinicians who care for patients with pulmonary disease should understand the principles of basic PF testing and should have a fundamental understanding of more sophisticated tests.

John D. Zoidis, MD, is a contributing writer for RT.

References
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