PFT INTERPRETATION

Inspiratory Reserve Volume

volume of air that can be inhaled after normal inspiration

3,100 ml

Normal Volume for Inspiratory Reserve Volume

Expiratory Reserve Volume

Volume of air that can be exhaled after normal expiration

1,200ml

Normal Volume for Expiratory Reserve volume

Tidal Volume

volume of air moves normally in and out of the lungs.

5-8 ml/kg

Normal value for Tidal Volume

Residual Volume

amount of air remaining in the lungs after a maximal expiration

Inspiratory Capacity

Maximum volume of air that can be inhaled from the normal resting end-expiratory level

VT + IRV

Formula for Inspiratory Capacity

Functional Residual Capacity

Volume of air remaining in the lungs at the resting end-expiratory level

ERV + RV

Formula for Functional Residual Capacity

Vital Capacity

Maximum volume of air that can be exhaled following a maximum inspiration

IRV + VT + ERV

Formula for Vital Capacity

Total Lung Capacity

Total amount of air inside the lungs after maximum inspiration

VT x F

formula for Ventilation

Direct Spirometry

Involves the use of a spirometer to measure the volumes of air moving into and out of a subject’s lungs during breathing

Indirect Spirometry

It is used to determine lung volumes that are not measurable by direct spirometry. These volumes are RV, FRC, and TLC

0.5 - 1 Hz

Normal Acceptable panting for Indirect Spirometry

Gas Dilution

Operate on Boyle's law except that the fractional concentration of a known gas is used instead of its partial pressure

Can only measure lung volumes in communication with conducting airways

Nitrogen washout

Used to determine the anatomical deadspace in the lungs

This technique can only measure gas that is in communication with the mouth

3-7 minutes

How many minutes of breathing 100% O2 to washout N2 from the lungs

less than 1.5%

Test is successfully completed when the N2 Levels decrease to become less than ___for at least 3 successive breaths

3-4 minutes

 Healthy subjects should washout N2 completely in

Tissot Spirometer

Collects the nitrogen that is exhaled after inhaling 100% oxygen

Helium Dilution

A technique for measuring functional residual capacity and residual volume

It is based on the principle that if a known volume and concentration of helium are added to a patient's respiratory system, the helium will be diluted in proportion to the lung volume to which it is added.

7 minutes

How many minutes until Helium is stable during Helium Dilution

less than 0.02% over a 30 second interval

during helium dilution, A state of equilibrium is defined as helium concentration changes of___, indicates that the test is succesful

Body  Plethysmograph

The amount of CHANGE in air pressure inside the box and CHANGE in volume during breathing is measured and used in the equation

sinusoidal pump, 30ml

What pump is used for calibrating the body pleth and how much ml

Ellipsoid Volume Method

Assumes that the lungs, in cross section through the chest, are basically elliptical in shape

Measurements are made on the x-rays that divide the thorax into a series of five vertical segments Its volume is determined on the basis of height, width and depth dimensions

Planimetry Method

Uses regression equations to correlate the lung surface areas measured on chest X rays to TLC measurements made by body plethysmographs

Obstructive Pattern

v Increase FRC is considered pathologic

v FRC values >120% of predicted represent air trapping

v Emphysematous changes

v Obstruction caused by asthma or bronchitis

Normal, Decreased, Increased, >35%+

n TLC ____

n VC ____

n FRC AND RV _____

n RV/TLC% _____

DURING OBSTRUCTIVE PATTERN

Restrictive Pattern

v FRC, RV and TLC typically decreased

v Usually lung volumes are decreased equally

v When TLC is <80% a restrictive process is present

v RV/TLC is relatively norma

Sarcoidosis, Tuberculosis, Pneumonectomy, Pneumonia

Intrinsic Restrictive Lung Disorders

Scoliosis/Kyphosis, Ankylosing Spondylitis, Pleural Effusion, Pregnancy, Gross Obesity, Tumors/Ascite

Extrinsinct Restrictive Lung Disorders

Generalized Weakness, Paralysis of the diaphragm, Myasthenia Gravis, Muscular Dystrophy, Poliomyelitis, Amyotrophic Lateral Sclerosis

Neuromuscular Restrictive Lung Disorders

Normal

Acute Asthma

Emphysema

Fixed Upper Airway Obstruction

Fibrosis