The body plethysmography test is the only precise way to measure lung volumes. With advancements in technology, including ultrasonic flow measurement, modern body plethysmography machines can detect even the smallest changes in pulmonary function.
In this article, you’ll find scientific evidence explaining why cabin-based body plethysmography offers unique advantages that establish it as the gold standard for detecting and diagnosing conditions like asthma and COPD.
By América Torres
Spirometry vs. Body Plethysmography
Spirometry provides precise details about lung function, but it requires patient cooperation to perform specific maneuvers. Additionally, environmental conditions can affect measurements in traditional equipments. While a good spirometer suffices in many cases, there are situations where a plethysmography cabin is indispensable. For example, spirometry does not provide data on total lung capacity (TLC) or residual volume (RV). Conversely, plethysmography not only delivers these results but also measures intrathoracic gas volume (ITG) and specific airway resistance (sRaw).
It’s important to clarify that spirometry and plethysmography complement each other and are used together, highlighting their unique benefits to meet patient needs effectively.
The Plethysmography Cabin Matters
As previously mentioned, environmental factors significantly impact pulmonary function test results. This is why traditional spirometers require calibration before testing (a step unnecessary with modern devices using ultrasonic technology).
Plethysmography booths use the principle of the Boyle-Mariotte law which states that, at a constant temperature, the pressure exerted by a gas is inversely proportional to the volume of its container. In other words, for a given amount of gas in a closed compartment, the relative changes in the volume of the compartment are always equal in magnitude, but opposite in sign to the relative changes in pressure. The great virtue of body plethysmography booths is that they allow detecting both changes in cabin pressure, as well as those of the pressure of the patient’s mouth on the mouthpiece, or the flow of breathing under controlled conditions. This is useful for determining static volumes and true flow resistance.
Therefore, by knowing the change in relative pressure, we know at the same time the change in relative volume. And after measuring the absolute volume change, it is possible to calculate the aforementioned relative volume, for which the reference pressure is always the barometric one. Therefore, the key to reliable and accurate plethysmography is that it is done inside a booth where the barometric pressure is under control. Simply put, plethysmography is the only way to MEASURE lung volumes.
A reliable and convenient test
Although body plethysmography requires a certain level of technical knowledge on the part of the person who applies it, it allows obtaining information about possible airway conditions and lung volumes that is not possible to obtain through any other pulmonary function test. But in addition, the use of plethysmography has several additional advantages:
- It is a non-invasive method
- It is more comfortable for the patient
- A few minutes are enough to obtain reliable values
- It requires little effort on the part of the patient, as the measurements are made during their normal breathing periods
- The results of specific airway resistance (sRaw) do not depend on the patient correctly performing the maneuver
And all of the above is possible thanks to the fact that the cabin provides a controlled pressure system (although in cabins that do not use an ultrasonic system it is necessary to perform calibration before the test) that facilitates reliable results with minimal inconvenience for the patient. As you may have already noticed, the body plethysmograph is a great ally when it comes to more detailed lung function tests. And this is more obvious when it is necessary to detect severe obstructions, for example, those that affect COPD patients.
Advanced Ultrasonic Plethysmography
SCHILLER-GANSHORN has leveraged over four decades of experience to develop the PowerCube Body+. We were the first manufacturers to introduce a plethysmography booth featuring ultrasonic flow measurement, providing advanced lung function assessments for detecting complex pathologies. Key features include:
- Real-time determination of exhaled gas
- No calibration required
- Real-time ATP–BTPS calculation
- Ultrasonic flow sensor that does not require calibration
- Resistance-free measuring sensor
- Advanced diagnostic capability for functional residual capacity and lung pathologies
- Compliance with ATS/ERS standards
Discover the cutting-edge capabilities of the PowerCube Body+ for unparalleled pulmonary diagnostics!
Transform Pulmonary Diagnostics with Body Plethysmography
Body plethysmography stands out as the gold standard for advanced lung diagnostics, delivering unmatched accuracy in measuring lung volumes, functional residual capacity, and airway resistance. Its patient-friendly, non-invasive design, enhanced by SharpFlow, SCHILLER-GANSHORN’s cutting-edge ultrasound technology, ensures precise and effortless results.
Elevate your diagnostic capabilities with the PowerCube Body+. Designed for both routine and complex cases, it empowers you to achieve accurate pulmonary assessments.
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