What instruction should a nurse give a client who is about to undergo pulmonary function tests?

The instruction for the client to refrain from smoking tobacco for 6 to 8 hours prior to pulmonary function tests is crucial because smoking can significantly affect the results of the tests. Tobacco smoke irritates the airways and can lead to constriction, which would skew the measurements of lung function, such as forced expiratory volume and forced vital capacity. By avoiding smoking before the test, the client can provide more accurate results that reflect their true lung function, facilitating proper assessment and management of any underlying respiratory conditions.

While hydration is generally important, drinking plenty of fluids before this specific test is not a necessary instruction and might even lead to discomfort during the test. Similarly, avoiding exercise for a certain amount of time before the test can be beneficial, but it is not typically specified as a strict guideline in relation to pulmonary function tests. Lastly, taking bronchodilator medications immediately prior could falsely elevate lung function test results, leading to misleading interpretations. Hence, avoiding smoking is the most pertinent and beneficial instruction to optimize test accuracy.