Spirometry is a type of Lung function test. Lung or Pulmonary function tests are carried out to check out the efficiency of your lungs. They also determine how much oxygen is efficiently supplied to the blood at any time. Spirometry, which is the most common and simple lung function test, helps in diagnosing various lung diseases. It also determines the severity of the disease and is done to cross check the efficacy of a lung treatment. Spirometry tests may be performed prior to lung surgeries. In respiratory diseases like COPD, abnormal test values point towards air trapping or air passage blockages.
Spirometry is done by breathing into a mouthpiece attached to a spirometer which records the readings. This test is performed using special instruments by professionals in a hospital. The readings are then analysed in a graph called spirogramThrough the Spirometry tests the following lung function values are determined and analysed:
Through the Spirometry tests the following lung function values are determined and analysed:
- FVC value (Forced Vital capacity): This involves taking the deepest possible breath and exhaling out the air with force.
Low FVC as well as FEV1 values can help diagnose the type of lung disease.
- FEV value (Forced expiratory volume): This number is used to determine the amount of air that is exhaled out forcefully in a single breath. The amount of forced exhaled air may be measured in 1, 2 or 3 seconds (FEV1, FEV2 and FEV3 respectively). A ratio can also be obtained of FEV1 and FVC. In lung diseases which are obstructive in nature, this ratio is lower than in normal people.
FEV1 is an important value to be monitored in COPD patients. A low FEV1 value indicates that there is a blockage in the air flow out of the lungs.
- PEF value (Peak expiratory flow): This measures the amount of air exhaled out with maximum force possible. This is usually simultaneously determined along with forced vital capacity or FVC test. This test is done to check for asthma.
- MVV value (Maximum voluntary ventilation): This measures the maximum quantity of air that can be breathed in and out in the span of 1 minute.
- SVC value (Slow vital capacity): This value gives you the measurement of the quantity of air that can be exhaled out slowly after a complete deep breath.
- TLC value (Total lung capacity): This measures the quantity of air present in the lungs after breathing in as much air as possible.
- FRC value (Functional residual test): This helps quantify the amount of air left in the lungs after exhaling out in a normal fashion.
- RV value (Residual volume): This measures the quantity of air present in the lungs after exhaling out as much air as possible.
- ERV value (Expiratory reserve volume): This measures the difference between FRC and RV values.
- FEF25-70 (Forced expiratory flow): This quantifies the flow of air halfway through an exhale cycle. It is used for the diagnosis and monitoring of small airway conditions like asthma.
Most times, these tests are repeated to see the consistency of the results obtained. Before performing spirometry, a bronchodilator may be administered to the subject to ease up the process. Spirometry is a valuable advancement in medical practice that enables doctors to accurately gauge the state of the patient’s lungs.