RESP 120 Chapter 5: Pulmonary Function Measurements

What is Inspiratory Reserve Volume (IRV)?

The maximum amount of air that can be inspired after a normal inspiration.

What is Tidal Volume (TV)?

A normal inspiration or expiration.

What is Expiratory Reserve Volume (ERV)?

The maximum amount of air that can be expired after the end of a normal expiration.

What is Residual Volume (RV)?

The amount of air left in the lungs after maximum expiration.

What is Inspiratory Capacity (IC)?

The combined inspiratory effort of tidal volume and inspiratory reserve volume.

What is the equation for Inspiratory Capacity?

IC = IRV + TV

What is Functional Residual Capacity (FRC)?

The amount of air left in the lungs after the end of a normal expiration.

What is the equation for Functional Residual Capacity?

FRC = ERV + RV

What is Vital Capacity (VC)?

The amount of air measured from maximum inspiration to maximum expiration.

What is the equation for Vital Capacity?

VC = IRV + TV + ERV

What is Total Lung Capacity (TLC)?

The maximum amount of air that can be held in the lungs at maximum inspiration.

What is the equation for Total Lung Capacity?

TLC = IRV + TV + ERV + RV

What is FEV1?

Forced Expiratory Volume in one second.

What is FVC?

Forced Vital Capacity, the total amount of air exhaled during a forced breath.

What does the FEV1/FVC ratio represent?

The fraction of total air exhaled in the first second of forced expiration.

What is the normal FEV1/FVC ratio?

75–80%.

What does DLCO measure?

Gas diffusion across the alveolar-capillary membrane.

What is the primary problem in obstructive lung disease?

Airflow limitation due to increased airway resistance.

What is the primary problem in restrictive lung disease?

Limited lung expansion due to reduced compliance or chest wall restriction.

Name four obstructive lung diseases.

COPD, asthma, bronchiectasis, cystic fibrosis.

Name four intrinsic restrictive lung diseases.

Pulmonary fibrosis, sarcoidosis, pneumonia, ARDS.

Name four extrinsic restrictive lung diseases.

Obesity, scoliosis, neuromuscular weakness, pleural effusion.

What is peak flow rate?

The maximum speed of exhalation after a full inspiration.

What does peak flow measure?

Airway obstruction and bronchoconstriction.

What condition is peak flow most commonly used to monitor?

Asthma.

How are peak flow values typically interpreted?

Compared to the patient’s personal best or predicted normal.

Which factors affect predicted normal lung values?

Age, sex, height, race/ethnicity, and body composition.

What 3 tests measure ventilated lung volume?

Helium dilution, nitrogen washout test, body plethysmography.

Which test measures total thoracic gas volume including trapped gas?

Body plethysmography.

Which residual volume measurement method is most accurate?

Body plethysmography.

What is the percent predicted equation?

(Measure value./ Predicted value) x 100

What percent predicted value is considered normal?

≥ 80%