You have become convinced that in order to effectively and accurately assess the degree and management of obstructive pulmonary disease, whether asthma or COPD, spirometry testing is essential. You have been exposed to spirometry tests being performed or were shown the technique for testing while attending an association congress, but you really need a refresher. Here are a few hints.
You need to keep in mind that spirometry is an effort-dependent test requiring the complete cooperation of the patient. In order to achieve this, you as the coach need to be totally involved with the testing. Be sure the patient is comfortable. Make a note as to whether the patient is seated or standing, because subsequent testing on that patient should be performed from that same position. If the patient is standing, have a chair behind him in the event that he becomes lightheaded after the blow. It is generally a good idea to have the elderly seated for the test. If he or she is wearing a shirt or blouse with a tight-fitting collar, have them unbutton the top button and if wearing a tie, they should loosen it.
Explain clearly and in simple terms that he or she will be performing a “breathing evaluation”. Try to avoid the word “test” since this has connotations of passing or failing and may make the patient apprehensive. Point out that they will be taking a slow maximal inhalation followed by a maximal exhalation, but that the exhalation will be as fast as they can and as hard as they can. Key them that you will be coaching them to continue to blow out for a minimum of six seconds. Assure them that it is quite normal to blow out for that period of time. The American Thoracic Society in their 1994 Standardization of Spirometry Update highly recommends that a six second blow be the goal for all spirometry testing.1
To ensure that the patient takes an adequate deep breath, it is valuable to emulate exactly what you expect. If the patient has a visual cue as to what a “big deep breath” is and can actually see and hear a forced expiration, he/she is more apt to perform well. Body language is the key to good performance. Instruct the patient to put the mouthpiece between his/her teeth and make a good, tight seal with their lips. After the patient slowly makes a maximal inspiration, the first phase of the test, loudly exhort the patient to blow. This element of surprise will help the patient to realize the fastest peak flow, which is the second phase of the test.
The third phase of the test, which involves diminished flow, is important to achieve the highest possible volume in the patient’s FVC. Traditionally, technicians have loudly instructed the patient to “blow, blow, blow…keep going, keep going!” to achieve the maximal forced volume, when the opposite approach may actually be more effective.
Dr. Paul Enright points out in a recent report that using the “soft sell” may be better for achieving the best performance during the third phase. He states, “…draw [the patient’s] attention to the motion of the bell of the volume spirometers, the computer incentive display, or the audio tone of the flow-sensing , which shows that he or she is continuing to get out some air.” “…Patients should be quietly told to ‘keep going; I can see you’re still getting more air out.'”2 This critical part of the test, since an obstructed patient may actually still be expelling a volume of air, but it may not seem apparent, and the test is stopped too soon. This results in a lower FVC than normal and when interpreted, may suggest that the patient is restricted. Many modern spirometers will alert you with an error message when it sees an abrupt cessation of flow so that a subsequent test can be performed correctly. Another key indicator might be to note the FET (Forced Expiratory Time) that is sometimes displayed as part of the data. If the time were appreciably shorter than six seconds, this would also suggest that the patient ended the test too quickly.
It is now recognized that if the patient blows out forcefully for six seconds (FEV6), this should be considered as a surrogate to the FVC3, and is adequate for most spirometry testing for obstructive lung disease. This is why it is imperative that you get your patient to blow out as long as possible. You might be surprised how long your obstructed patient can continue to blow.
Finally, be sure that you have test reproducibility. According to the ATS, this is represented by two FVC’s that are within 200mL of each other and two FEV1’s that are within 200mL of each other1. This will give further assurance that the tests are the “best” that the patient had to offer.
Realize that the scope of this article does not fully describe all that needs to be known in order to have a full understanding of the scope of spirometry testing. As with most medical diagnostic testing, it is always best to have on hand for thorough review all the recommendations made in the literature. The American Thoracic Society has published all its guidelines in “Standardization of Spirometry” American Journal of Respiratory and Critical Care Medicine Vol 152. Pp 1107-1136, 1995