A 35 Year Old Man Goes For Physical Examination For Job Fitness

A 35 year old man is having a physical examination as a requirement for job fitness. He is asked to do a pulmonary function test and blow through a spirometer.

What is spirometry?

Spirometry is a powerful tool that helps measure the functional lung volumes and detect any underlying obstructive or restrictive lung disorders.

Below is a graph to help understand lung volumes:

Spirometric values

FVC—Forced vital capacity; the total volume of air that can be exhaled during a maximal forced expiration effort.

FEV1—Forced expiratory volume in one second; the volume of air exhaled in the first second under force after a maximal inhalation.

FEV1/ FVC ratio—The percentage of the FVC expired in one second.

FEV6 —Forced expiratory volume in six seconds.

FEF25–75%—Forced expiratory flow over the middle one half of the FVC; the average flow from the point at which 25 percent of the FVC has been exhaled to the point at which 75 percent of the FVC has been exhaled.

MVV—Maximal voluntary ventilation.

Lung volumes

ERV—Expiratory reserve volume; the maximal volume of air exhaled from end-expiration.

IRV—Inspiratory reserve volume; the maximal volume of air inhaled from end-inspiration.

RV—Residual volume; the volume of air remaining in the lungs after a maximal exhalation.

VT —Tidal volume; the volume of air inhaled or exhaled during each respiratory cycle.

Lung capacities

FRC—Functional residual capacity; the volume of air in the lungs at resting end-expiration.

IC—Inspiratory capacity; the maximal volume of air that can be inhaled from the resting expiratory level.

TLC—Total lung capacity; the volume of air in the lungs at maximal inflation.

VC—Vital capacity; the largest volume measured on complete exhalation after full inspiration.