Ellisnore, MO (PressExposure) June 03, 2009 -- Until now, there has not been a reliable method to ensure accurate test results of a body plethysmograph, sometimes known as a "Body Box." PFT Diagnostics, LLC, authorized dealer for Morgan Scientific pulmonary function products, is now offering the all-new VTG Calibrator plethysmograph simulator to provide independent quality control for VTG measurements.
The body plethysmograph is regarded as the most reliable instrument to obtain lung volume data in all test subjects regardless of obstructive lung disease. Whereas traditional gas dilution techniques (closed-circuit helium dilution and nitrogen washout) are compromised by gas distribution and airway communication in the lungs, the plethysmograph makes measurements by pressure change and can access those 'hidden' lung volumes.
For measurements of plethysmography, the subject is enclosed in a sealed cabin (enclosure) equipped to measure pressure, flow or volume changes. The differential pressure measurements are of Box Pressure (the pressure changes measured within the sealed cabin) and Mouth Pressure (the alveolar pressure changes recorded at the mouth when the patient valve is occluded). Flow is measured using the principle of pneumotachography; the flow signal is integrated to obtain Volume. A change in the volume of air in the lungs from breathing maneuvers can be estimated from the expansion or the compression of gas in the plethysmograph.
The most common measurements made using a body plethysmograph are Thoracic Gas Volume (VTG) and Airways Resistance (Raw). Since the measurements utilize Boyles Law (which states at constant temperature, the absolute pressure and the volume of a gas are inversely proportional), it is useful to consider the thermodynamic conditions that exist inside a plethysmograph. The calibrator has been designed in recognition that Boyle's law only holds under completely isothermal conditions.
Designed to work with any make of body plethysmograph, the VTG Calibrator uses wireless Bluetooth technology to communicate with either a Palm or Windows Mobile PDA device. The operation of the VTG Calibrator is straightforward and within 25 seconds produces test results with a
To request more information about the VTG Calibrator or any other pulmonary function test equipment, visit http://www.pftdiagnostics.com or call (877) 738-3424.