EQUIPMENTS FOR VOLUME AND FLOW MEASUREMENT

Spirometers

Instruments used to measure the volumes of air that are inhaled and exhaled, during breathing.

Primary Volume Measuring Spirometers

The volume of air moving into and/or out of the lungs is measured directly. while airflow is measured indirectly

Primary Flow Measuring Spirometers

Directly measure the flow rate of the inhaled and/or exhaled air while it measures volume indirectly

Volume-Displacement Spirometers

The subject’s expiratory air moves into the spirometer, and his or her inspiratory air moves back out from it, The volume, or size, of the spirometer increases and decreases proportionally with subject breathing.

Flow-through spirometers

A device that measures air as it passes completely through. But volumes are not collected within the device.

Volume-Displacement Spirometer and Flow-through spirometer

2 categories of Primary Volume Measuring Spirometers

Water-sealed, Dry-sealed, or bellows type

Examples of volume-displacement Spirometers

Rotor/Turbine Spirometer

Example of a flow-through spirometer and The only type of PVM spirometer that allow the measured air to pass completely through the device as the volume is measured.

Water-sealed spirometer

➔Consist of a double-walled, stationary cylinder that has water between the double walls.

Inhales, Exhales

The spirometer bell moves downward as the subject and upward as the subject __.

13.5 L

Spirometer bell’s volume capacity

41.27 mL

Bell factor

86mm

spirometer bell movement

Chain-compensated spirometer

very accurate for simple volume measurement; Unfortunately, with breathing maneuvers that include rapid respiratory rates or rapid changes in air flow rates, some accuracy is lost.

Stead-Wells spirometer

was developed in response to the inertia problems exhibited by the chain-compensated configuration

Dry-sealed spirometer

They consist of a rod-mounted piston within a cylinder. The piston is made of plastic or a lightweight metal. Because it is designed to move horizontally, the piston does not require counterweight mechanism.

Bellows Spirometer

➔Constructed of a flexible plastic material that is designed to collapse in folds.Unfolds and expands with the subject’s expiration and collapses with his or her inspiration

Fully expanding bellows

A type of bellows spirometer that opens and closes like an accordion

Wedge-shaped bellows

Fully expands only along one edge, similar to the opening and closing of a book

Wright-Type spirometer

The most frequently used configuring of the rotor spirometer

Differential-pressure pneumotachometers, thermal anemometers, and ultrasonic sensor spirometer

Examples of Primary flow measuring spirometers

Differential-Pressure Pneumotachometers

They function on the basis of how changes in air flow rates through the element affect upstream/downstream pressure relationships within the device

Poiseuille’s evaluation

The basis for using pressure to determine flow rates of the differential-pressure pneumotachometers

Thermal Anemometers

Air flow rate is measured on the basis of how it affects the temperature of a heated element. Gas moving through the sensor carries heat from the element cooling the metal rod = measurement of flow

Ultrasonic Sensor Spirometer

It uses a beam of ultrasonic sound waves to measure air flow. The beam detects a special type of gas stream turbulence called a vortex. The sensor transmits a sound beam across and through the gas stream.

Dedicated Peak flow meters

Another type of flow-measuring device. However, to measure only the peak expiratory flow rate. The subject exhales with maximal force into the device. The force of the expiratory air flow pushes the vane rapidly forward.

Body plethysmograph, Inductive plethysmograph

2 types of Plethysmograph

Body plethysmograph

measures the intrathoracic gas volume (VTG) and airway resistance (Raw)

Inductive plethysmograph

uses elastic bands with wires (inductive coils) placed around the chest and abdomen.used to measure breathing movement without needing a mouthpiece or airflow sensor.

600 L

Volume of the cabinet of a body plethysmograph

Nonconstant-volume plethysmograph cabinet, Constant-volume variable-pressure plethysmograph cabinet

2 methods for measuring BP cabinet volume changes

Directional breathing valves

The purpose of the valve is to separate the direction of the subject’s inspiratory air flow from the direction of the expiratory air flow

Directional Control Valves

They permit control and changes in the direction of gas flow within the breathing circuit

Recorders

provide a hard copy of a subject’s test results

Mechanical chart recorders

A type of recorder that require the movement of both the paper and the recording pen

Electronic Chart recorders

Any measuring system that can produce an electrical signal can use an electronic chart recorder.

Bedside, Physician’s clinic, Other non-healthcare setting

Settings in which testing is performed

Medical Diagnosis, Surgery-related evaluation, Disability Evaluation, Public health/research

Indications for testing