randy test 2 based on study guide

What does spirometry measure?

Lung volumes, capacities, and flow rates.

The most clinically important spirometry measurement is:

FVC (Forced Vital Capacity).

What does FEV₁ measure?

The volume of air exhaled in the first second of the FVC maneuver.

What spirometry value is the primary indicator of airflow obstruction?

FEV₁/FVC ratio.

What spirometry maneuver measures IRV, VT, ERV, IC, and VC?

Slow Vital Capacity (SVC).

What spirometry maneuver measures flow rates like FEV₁ and PEFR?

Forced Vital Capacity (FVC) maneuver.

How long must a patient exhale during an FVC maneuver?

At least 6 seconds or until a plateau is reached.

What spirometry pattern shows ↓FEV₁, normal/↓FVC, and ↓FEV₁/FVC?

Obstructive pattern.

What spirometry pattern shows ↓FEV₁, ↓FVC, and normal or ↑FEV₁/FVC?

Restrictive pattern.

What rule must be remembered when diagnosing restriction?

Restriction cannot be confirmed without TLC measurement.

What does a normal flow-volume loop look like?

Sharp peak with a smooth expiratory curve.

What does a scooped-out expiratory limb indicate?

Obstructive lung disease.

Diseases commonly causing scooped expiratory loops include:

COPD and asthma.

What flow-volume loop pattern shows a flattened inspiratory limb?

Variable extrathoracic obstruction.

Example cause of variable extrathoracic obstruction:

Vocal cord dysfunction.

What flow-volume loop pattern shows flattened expiratory limb?

Variable intrathoracic obstruction.

What pattern shows flattening of both inspiratory and expiratory limbs?

Fixed upper airway obstruction.

Examples of fixed airway obstruction:

• Tracheal stenosis
• Large airway tumor.

What lung volumes cannot be measured by spirometry?

• RV
• FRC
• TLC.

How are RV and TLC obtained?

Calculated after measuring FRC.

What does RV represent?

Air remaining in lungs after maximal exhalation.

What lung volume increase indicates air trapping?

RV ↑.

What lung volume increase indicates hyperinflation?

TLC ↑.

Diseases commonly causing air trapping and hyperinflation:

• COPD
• Emphysema
• Severe asthma.

Two gas dilution methods used to measure FRC:

• Helium dilution
• Nitrogen washout.

What is the major limitation of gas dilution tests?

They underestimate lung volumes when air trapping is present.

Why do gas dilution tests underestimate lung volumes in COPD?

They measure only air communicating with the airways.

What lung volume method measures all thoracic gas including trapped air?

Body plethysmography.

What physical law is body plethysmography based on?

Boyle’s Law.

What does body plethysmography directly measure?

FRC (thoracic gas volume).

Why is plethysmography preferred in COPD?

It measures trapped air not communicating with airways.

What defines a significant bronchodilator response?

≥12% AND ≥200 mL increase in FEV₁ or FVC.

Why is the 200 mL rule important?

The response must meet both percentage and volume criteria.

How long should SABA (Albuterol) be withheld before spirometry?

4–6 hours.

How long should SAMA (Ipratropium) be withheld?

~6–12 hours.

LABA withholding time before testing:

~12–24 hours.

LAMA withholding time:

~24–48 hours.

Should inhaled corticosteroids be withheld before spirometry?

No.

What does DLCO measure?

Gas diffusion across the alveolar-capillary membrane.

What gas is used to measure DLCO?

Carbon monoxide.

Why is carbon monoxide used in DLCO testing?

It has very high affinity for hemoglobin, making diffusion measurable.

What breath hold time is required during DLCO testing?

8–12 seconds (~10 seconds).

Minimum inspired volume during DLCO maneuver:

≥85–90% of vital capacity.

Diseases that decrease DLCO:

• Emphysema
• Pulmonary fibrosis
• Pulmonary embolism
• Anemia.

DLCO is usually normal or increased in what disease?

Asthma.

What DLCO severity range indicates moderate impairment?

40–60% predicted.

What does a Z-score represent in PFT interpretation?

Number of standard deviations from predicted value.

What is the lower limit of normal (LLN) for Z-scores?

−1.64.

If a patient’s FEV₁ z-score is −2.3, what does it mean?

Below normal.

Acceptable repeatability for FVC values:

Two largest values within 150 mL.

Three important spirometry quality indicators:

• Good start of test
• No cough in first second
• Adequate exhalation.

What artifact produces spikes on a flow-volume loop?

Cough.

What does an abrupt end of expiration indicate?

Early termination of the maneuver.

What is back-extrapolation error?

Poor start of the spirometry maneuver.

First step when interpreting spirometry values?

Look at FEV₁/FVC ratio.

If FEV₁/FVC is decreased, what pattern is present?

Obstruction.

If FVC is decreased but FEV₁/FVC is normal, what is suspected?

Restriction.

What confirms restrictive lung disease?

TLC <80% predicted.

What does increased RV indicate during interpretation?

Air trapping.

What pattern suggests emphysema?

Obstruction + decreased DLCO.

What pattern suggests asthma?

Obstruction + normal DLCO.