Plethysmography is widely considered the most accurate test for lung volumes; however, for those with obstructed airways, such as those with COPD or asthma, there may be a better way.
Chronic Obstructive Pulmonary Disease
COPD is a disease characterized by chronic airflow limitation and depending on the severity of the disease, lungs may be hyperinflating, or air trapping, and gas exchange abnormalities may be present. In order to decipher and diagnose the progression of COPD, it is critical to have an accurate method to evaluate lung volumes.
When a patient with normal lung function is tested, there is no difference between the usage of Plethysmography versus Helium Dilution; however, if a patient presents with airflow obstruction, it has been noted that Plethysmography tends to over estimate TLC (Total Lung Capacity) in these individuals.
This is due to lung hyperinflation and air trapping that these individuals may experience over the course of their disease.
It is suggested that due to the panting maneuver during Plethysmography, mouth pressure swings may not be equal to alveolar pressure swings.
Functional Residual Capacity
Because the Helium Dilution method (FRC) does not require panting and instead, the patient is only required to breathe normally and complete a single SVC (slow vital capacity) at the end of the test, this is not the case and FRC tends to be more accurate.
Also, because the FRC test introduces additional oxygen during the test, it is specifically beneficial to those that tend to desaturate, such as a patient with severe COPD.
In addition, Morgan Scientific’s SpiroAir design does not require a demand valve, which increases patient comfort even further.
If your patient demographic is largely made up of those that suffer from COPD, Plethysmography might not be the best choice when establishing lung volumes.
Save some space and money and contact Morgan Scientific for more information on the SpiroAir with our corresponding ComPAS2 software for simple yet research grade testing, workflow optimization and flexibility, and integration with your EMR!
For more information, contact us by email or phone.