If a person is having lung problems, they may exhibit symptoms such as excessive fatigue and difficulty in breathing. This can severely affect the overall quality of the person’s life and restrict them from enjoying many activities and experiences. There are several tests that can be used to diagnose lung diseases and help the doctor create a suitable care plan.
Body plethysmography is a non-invasive and safe procedure that is used by doctors to eliminate the possibility of certain lung diseases, such as asthma. Based on the results, the doctor can diagnose COPD, that is, chronic obstructive pulmonary disease, or suggest other tests. Although this test can indicate if there is a health problem affecting the patient’s lungs, it cannot provide the source of the problem.
What is Body Plethysmography?
A pulmonary/lung function test (PFT), body plethysmography, allows the doctor to evaluate the amount of air the lungs can hold. It is a non-invasive test that is safe, and generally, does not cause discomfort for the patient. By conducting a body plethsymogrpahy test, the doctors can check the patient’s:
- Functional residual capacity (FRCpleth), which is the amount of air left in the lungs after passive exhalation
- Residual volume
- Total lung capacity
- Specific airway resistance (sRaw).
Body plethysmography is especially beneficial in the diagnosis and management of chronic obstructive pulmonary disease (COPD) and emphysema. It is often referred to as lung plethysmography or pulmonary plethysmography; it is may also be referred to as whole body plethysmography sometimes.
This test is performed in an enclosed air-tight box in which the patient has to sit and breathe for some time, while the machine measures the amount of air going in and out of their lungs during the patient’s breathing. The test is based on a simple principle that uses volume and pressure to evaluate test results. As the patient breathes in, their lungs expand causing the volume of the air in the chamber to decrease and the pressure inside the chamber to increase. This subtle change in the pressure of the box and the mouthpiece used by the patient, is then interpreted by a computer as different parameters of the body plethysmography test to figure out if the patient has any lung ailments.
The average cost of body plethysmography is about INR 300 in Delhi, and the prices depend on the availability of the plethysmograph box and other factors. A body plethysmography test is often recommended in addition to other PFTs, and the collective price of these tests will likely be less than the price of each individual tests.
Why is Body Plethysmography Recommended?
The doctor will likely recommend a body plethysmography test if the patient experiences symptoms, including the ones listed below, related to health problems with the airway or lung function.
- Pressure, pain, or tightness in the chest
- Difficulty in taking deep breaths
- Coughing with/without mucus
- Shortness of breath
- Wheezing
A non-invasive efficient pulmonary function test, body plethysmography, can help in diagnosing health problems with the lungs or airway, including COPD, pulmonary fibrosis, and asthma. Some other purposes of body plethysmography include the following:
- To compare the patient’s current lung function with standard or ideal lung functioning
- To measure the effect of chronic diseases on the patient’s lungs
- To determine whether any environmental factors caused impaired lung function in the patient
- To evaluate the patient’s ability to tolerate medical procedures, such as surgery
- To detect changes in the patient’s lung function that may indicate the need to change/alter treatment
Body plethysmography test is relatively quick, as it usually takes less than 20 minutes to perform, and accurate for diagnosing the health problems of the respiratory system. An abnormal body plethysmography test enables the healthcare provider to either confirm their theory and proceed with the diagnosis or order additional tests to find the correct diagnosis.
Preparing for Body Plethysmography
The doctor will give you proper instructions to help you prepare for the body plethysmography. The patient should do the following:
- Do not smoke at least one hour before the test
- Do not perform high-resistance or heavy exercises at least 30 minutes prior to the test
- Wear comfortable clothes that do not restrict your upper body or abdomen while breathing
- Do not eat heavy meals at least two hours before the test
- Do not consume alcohol at least four hours before the test
- Inform the doctor upon noticing the symptoms of any contagious respiratory infection such as flu or cold
- Notify the doctor about all medicines
The above-mentioned guidelines may be modified by the doctor depending on the patient.
Procedure of Body Plethysmography
The test is performed by a healthcare provider or, usually, a lab technician under the supervision of a pulmonologist or a doctor in any of the following locations:
- Pulmonary function laboratories
- Cardiopulmonary laboratories
- Clinics
- Pulmonology offices
The patient goes through the pre-test checklist with the lab technician and gets their vitals checked. After everything is ready, the patient goes inside the volume-constant whole-body plethysmograph, a special air-tight apparatus used for the test. The patient either sits or stands in the see-through box.
The lab technician will place a nose clip on the patient’s nose to ensure they breathe only through their mouth using the mouthpiece provided inside the box. They will also give instructions to breathe differently—rapid and shallow breaths, normal breaths, or slow and deep breaths—through an intercom device inside the box. The box is sealed air-tight and has controlled pressure at the beginning of the test. The patient must signal the technician if they feel any discomfort during the procedure; the test does not cause any pain to the patient. If the patient is claustrophobic, they should inform their doctor to get some medicines to relax during the test.
Interpreting results
The test results will indicate an abnormality if the patient has a lung ailment, such as deterioration of the lungs, issues with lung expansion and contraction, or problems with the chest wall muscles. Body plethysmography is extremely beneficial in diagnosing COPD, as it evaluates the patient’s lung capacity and caches the symptoms of the disease. However, it cannot confirm the diagnosis of other lung diseases; the doctor generally recommends further tests, such as spirometry, gas exchange testing, and/or arterial blood gas test, if the results show abnormality, but the patient doesn’t necessarily have COPD.
The normal results for the body plethysmography test depend on various factors such as the patient’s age, sex, height, weight, and tobacco product use. Additionally, it is unlikely to get false results if the patient has prepared for the test according to the guidelines given by the doctor. However, in certain cases, the doctor may recommend the patient to get body plethysmography again if they suspect false results the first time.
