TEST FOR PULMONARY MECHANICS

Spiromtery, Recording system

Equipments needed for pulmonary test

Forced Vital Capacity Maneuver

Most frequently used method for assessing dynamic pulmonary function.

Volume-time curve

A curve which has volume on vertical axis, and time on horizontal axis

FVC

The volume change of the lung between a full inspiration to total lung capacity and a maximal expiration to residual volume. (FORCED)

4 to 6 seconds

What is the total expiratory time needed to completely exhale the FVC in a normal lung function

IVC (Inspiratory Vital Capacity)

The volume change of the lung between a maximal expiration to residual volume and a full inspiration to total lung capacity.

EVC (Expiratory Vital Capacity)

The volume change of the lung between a full inspiration to total lung capacity and a maximal expiration to residual volume but not forced

FEVt

An indication of the average flow rate over a time interval

60%

In normal lung function, the percentage of total FVC exhaled in FEV0.5

83%

In normal lung function, the percentage of total FVC exhaled in FEV1

94%

In normal lung function, the percentage of total FVC exhaled in FEV2

97%

In normal lung function, the percentage of total FVC exhaled in FEV3

FEV1

The volume exhaled during the first second of a forced expiratory maneuver started from the level of total lung capacity.

FEFx%

Maximum expiratory flow when x% of the FVC has been exhaled

FEF200-1200

Measures flow early in the expiratory maneuver, First 200-1200mL

8 L/sec (480 L/min)

In normal lung function, the average FEF200-1200 for men ages 20-30

5.5 L/sec (330 L/min)

In normal lung function, the average FEF200-1200 for women ages 20-30

as low as 1 L/sec

In abnormal lung function, the FEF200-1200 is

FEF25%-75%

Measures expiratory flow rates at a later point in the maneuver than FEF 200-1200

4.5 L/sec (270 L/min)

In normal lung function, FEF25%-75% for men ages 20 to 30 is

3.5 L/sec (210 L/min)

In normal lung function, FEF25%-75% for women ages 20 to 30 is

as low as 0.3 L/sec

In abnormal lung function, FEF25%-75% IS

FEF 75%-85%

Measures expiratory flow rates towards the end of the maneuver

Flow-Volume Loop

Flow on vertical axis;  volume on horizontal axis, Allow for inspiratory and expiratory peak flow rates to be read directly from graph

Peak Expiratory Flow

flow generated during expiration performed with maximal force and started after a full inspiration

10 L/sec (600/Lmin)

In normal lung function, the average PEFR for men ages 20 to 30 is

7.5 L/sec (450 L/min)

In normal lung function, the average PEFR for women ages 20 to 30 is

FIVC

The volume change of the lung between a maximal expiration to residual volume and a full inspiration to total lung capacity. FORCEFULLY

FIV1

The volume that can be forcefully inhaled in the first second during a forced inspiratory maneuver started from residual volume.

Small Airway Obstruction

The latter portion of the expiratory loop begins to take on a concave appearance

Fixed Large Airway Obstruction

causes relatively equal decreases in both expiratory and inspiratory flow rates

Intrathoracic Variable Large Airway Obstruction

causes a flattening of the expiratory portion of a flow/volume loop caused by the limitations of expiratory flow.

Extrathoracic Variable Large Airway Obstruction

cause a flow limitation on inspiration, with a characteristic flattening of the flow/volume loop's inspiratory portion

Low-Density Gas spirometry

Measuring FVC maneuver after the subject has breathed a helium/ oxygen

80%He / 20%O2

Percentage of Helium and O2 mixture if heliox

Volume of Isoflow

Maximum or earliest flow rate that is controlled by density- independent flow through small, peripheral airway

Peak Expiratory Flow Monitoring

This test requires a peak expiratory flow meter: a small handheld device with a mouthpiece at one end and a scale with a moveable indicator

Green Zone

80 to 100 percent of the usual or normal peak flow readings are clear.

Asthma is under good control.

Yellow Zone

50 to 79 percent of the usual or normal peak flow readings

Indicates caution.

Red Zone

➔ Less than 50 percent of the usual or normal peak flow readings

➔ Indicates a medical emergency.

80-100%

Green zone Percentage for peak expiratory flow monitoring

50-79%

Yellow zone percentage for peak expiratory flow monitoring

less than 50%

Red zone percentage for peak expiratory flow monitoring

Maximum Voluntary Ventilation

➔ Largest volume that a subject can breathe in and out of the lungs in one minute with maximum voluntary effort.

10-15 seconds

What is the amount of time for measurement during MVV

170 L/min

The average MVV for normal lung function for men ages 20 to 30

110 L/min

The average MVV for normal lung function for women ages 20 to 30

Airway Resistance

The drive pressure required to create a flow of air through a subject's airway.

Elastic Recoil Pressure/Compliance

An indication of the elastic force that is generated by the thoracic / lung system when the lungs are expanded.

Compliance

The amount of transpulmonary pressure change required to produce a certain change in lung volume.

Dynamic Compliance

Distensibility of the lungs and thorax during breathing

Maximum Inspiratory and Expiratory pressure

measures subject's ventilatory muscle strength.

MIP

is a measure of the most negative (subatmospheric) pressure that can be generated with an inspiratory effort.

MEP

is the greatest positive pressure that a subject can generate.

three-way directional breathing valve or a shutter mechanism

Equipment needed for maximum inspiratory and expiratory pressure

-20 cmH20 or smaller

MIP value that needs mechanical ventilatory support

less than +40cmH20

MIP value = difficulty in coughing and clearing secretions. = generalized neuromuscular disorders