Lung Volumes-Body Plethysmography Body plethysmography is a very sensitive lung measurement used to detect lung pathology that might be missed with conventional pulmonary function tests. Some gas remains in the lungs even after you blow out as much as possible. This is known as the residual volume and can be high due to air trapping. Air trapping can be a symptom of some lung diseases. The test is conducted with the subject seated in an airtight chamber, referred to as a body box. The Respiratory Scientist is able to communicate with the patient through an intercom and instructs them on how to breath during the test. The box has high visibility so the patient and the scientist are able to see each other during the test. As spirometry and gas transfer tests are conducted prior to lung volumes one hour is set aside for this appointment. This test is only available in Hamilton. This information is intended as a guide only. Information specific to you as an individual should be sought from your family doctor or respiratory specialist.