Spirometry is a pulmonary function test that measures the volume of air that can be inspired and expired as a function of time. The primary signal measured in spirometry may be volume or flow.
Maximum expiratory flow-volume curves are measured before and after bronchodilator administration to test for reversibility of airflow limitation or to assist in diagnosing Asthma versus COPD.
A spirometry test may also be conducted as part of a bronchial challenge test, used to determine bronchial hyper-responsiveness to either rigorous exercise, inhalation of cold/dry air, or with a pharmaceutical agent such as mannitol.
An indication of maximum inspiratory capacity and performance can also be measured to assess the degree of fixed or variable airway obstruction.
The measurements from spirometry are valuable as a screening tool for respiratory health however spirometry alone cannot lead to a diagnosis.
There are many potential causes for nasal obstruction. Some of the most common causes are allergic rhinitis, deviation of the nasal septum, or sinus or nasal infection.
Nasal obstruction is typically diagnosed by a patient's subjective complaint of nasal stuffiness coupled with a physical examination demonstrating anatomic restriction of the nasal passages.
Rhinomanometry and acoustic rhinometry are objective tests that assess nasal airway patency.
Rhinomanometry measures air pressure and the rate of airflow during breathing. These measurements are then used to calculate nasal airway resistance.
Acoustic rhinometry uses a reflected sound signal to measure the cross-sectional area and volume of the nasal passage.
Acoustic rhinometry gives an anatomic description of a nasal passage, whereas rhinomanometry gives a functional measure of the pressure/flow relationships during the respiratory cycle.
A Lung Function Test (LFT) consists of measurements that provide the basic assessment of respiratory function.
The LFT defines the function of the airways and alveoli and consists of the following measurements:
- Maximum expiratory flow volume curves (FVC) before and after bronchodilator.
- Lung Volumes: total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV) and vital capacity (VC) using plethysmography.
- Single breath carbon monoxide transfer factor (DLCO) and transfer factor corrected for the effective alveolar volume (DL/VA).
- Respiratory muscle strength is an additional test conducted on specific request which measures the maximum mouth pressures generated during expiratory effort at TLC (MEP) and during inspiratory effort at RV (MIP). This test may be requested if the TLC is below the lower limit of normal (LLN: one standard deviation below the predicted TLC) with unexplained cause.
- Maximum inspiratory flow volume curves can also be measured on specific request to assess the degree of fixed or variable upper airway obstruction.
The 6MWT is a practical simple test conducted for the objective evaluation of functional exercise capacity.
This test measures the distance that a patient can quickly walk on a flat, hard surface in a period of 6 minutes (the 6MWD).
It evaluates the global and integrated responses of all the systems involved during exercise, including the pulmonary and cardiovascular systems, systemic circulation, peripheral circulation, blood, neuromuscular units, and muscle metabolism.
It does not provide specific information on the function of each of the different organs and systems involved in exercise or the mechanism of exercise limitation, as is possible with maximal cardiopulmonary exercise testing.
The self-paced 6MWT assesses the submaximal level of functional capacity.
Most patients do not achieve maximal exercise capacity during the 6MWT; instead, they choose their own intensity of exercise and are allowed to stop and rest during the test.
However, because most activities of daily living are performed at submaximal levels of exertion, the 6MWD may better reflect the functional exercise level for daily physical activities.