End of test criteria

It is important for subjects to be verbally encouraged to continue to exhale the air at the end of the manoeuvre to obtain optimal effort. End of test criteria are used to identify a reasonable FVC effort, and there are two recommended criteria:

Although subjects should be encouraged to achieve their maximal effort, they should be allowed to terminate the manoeuvre on their own at any time, especially if they are experiencing discomfort.

The test should be terminated by the healthcare practitioner should they be alerted that the patient is experiencing discomfort.

For patients with obstructive airways disease or in the elderly, exhalation times of >6s are frequently needed. However, exhalation times of >15s will rarely change clinical decisions.

Multiple prolonged exhalations are seldom justified and may cause light headedness, syncope, undue fatigue and unnecessary discomfort.

Early termination, by itself, is not a reason to eliminate all the results from such a manoeuvre from further consideration. Information such as the PEF and the FEV1 may be useful (provided they have blown beyond 1 second of course) and can be reported from these early terminated manoeuvres.

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