Pulmonary Function Test Interpretation Strategies

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What is the interpretive criteria for FVC and SVC in patients without obstruction?

FVC and SVC should be within 150 mL of each other

How long should healthy adults typically take to expire their FVC?

4 to 6 seconds

What may be indicated if FVC is less than the lower limit of normal (LLN)?

Lung volumes may be indicated

What is the forced expiratory time (FET) typically like in patients with severe obstruction?

15 seconds or more Signup and view all the answers

How should spirometers measure FVC according to ATS-ERS recommendations?

For at least 15 seconds Signup and view all the answers

In what specific cases may lung volumes and/or muscle pressures be indicated during spirometry?

If FVC and FEV1 are both reduced proportionately Signup and view all the answers

What is an alternative to measuring FVC in severely obstructed patients?

FEV6 Signup and view all the answers

The use of FEV1/FEV6 instead of FEV1/FVC reduce the sensitivity of spirometry to detect airway obstruction. T or False?

True Signup and view all the answers

The reduction in FVC may be more evident than that of the slow VC in what type of diseases?

Diseases affecting the bellows function of the chest. Also in obstructive disease with air trapping, Signup and view all the answers

What does an FVC significantly lower than SVC suggest?

Airway collapse and gas trapping. Signup and view all the answers

How can premature termination of the FVC effort affect FEV1%?

It may cause FEV1% to be overestimated, masking the presence of obstruction. Signup and view all the answers

What issue can result in a large FVC derived from a flow sensor?

Improper zeroing or contamination of the sensor by condensation or mucus. Signup and view all the answers

How can poor repeatability of measurements within a single testing session be recognized?

Characterized by progressively increasing test results. Improper zeroing or contamination of the sensor by condensation or mucus. Signup and view all the answers

What do patients do that may cause FEV1% to be overestimated?

Stop exhaling before achieving an obvious plateau or fail to take a maximal inhalation. Signup and view all the answers

What is the consequence of patients failing to take a maximal inhalation during spirometry?

They will typically have an underestimated FVC. Signup and view all the answers

What does it suggest if both FVC and FEV1 are reduced proportionately?

If FVC and FEV1 are both reduced proportionately, restriction may be present. Signup and view all the answers

What spirometric result suggests that lung volumes may be indicated?

If FVC is less than the lower limit of normal (LLN), lung volumes may be indicated. Signup and view all the answers

Interpretative Strategies for FVC Maneuver

<ol> <li>Were at least three acceptable spirograms obtained? Are FVC and FEV1 repeatable (within 150 mL)? 2. Are reference values appropriate? Age? Sex Height? Race? 3. Is FEV1% (ratio) less than predicted? If so, obstruction is present. a. Is FVC also reduced? If so, is it caused by obstruction or restriction? b. If FVC is less than the LLN, lung volumes may be indicated. c. Is the obstruction reversible? Bronchodilators may be indicated. 4. Is FEV1% equal to or greater than expected? a. Are FVC and FEV1 both reduced proportionately? If so, restriction may be present; lung volumes and/or muscle pressures may be indicated. b. Are FVC and FEV1 within normal limits? If so, spirometry is likely normal. 5. Are the spirometric findings consistent with the patient history and physical findings? Is bronchial challenge indicated to reveal obstruction?</li> </ol> Signup and view all the answers