Lecture 17 Flashcards
What can pulmonary function testing assess?
- Ventilation (including lung mechanics).
- Gas exchange.
- Perfusion (quality and quality).
- Respiratory control.
What can respiratory function asses?
- Impact of a pathological or raging process.
- To tract the progress of a disease process and/or treatment regimen.
- Assess degree of interventional risk or risk associated with specific activity.
What are the type of lung function tests?
- Spirometry (dynamic volumes). Most common test and the hardest test to do properly.
- Static lung volumes. What is the total lung capacity of your lung.
- Diffusion capacity (DLco). used to assess how effective your alveolar capillary membrane at exchanging gas.
- Bronchodilator response. Tell us if a person responds positively to the amount of bronchodilator given to them.
- Bronchoprovocation tests.
- Cardiopulmonary exercise testing.
Describe spirometry/FVC?
Spirometry requires the concurrent measurement of flow and volume during a maximal effort expiration followed by a maximal effort inspiration.
What are the indications in spirometry?
- Toe establish or confirm a diagnosis “obstructive ventilatory defect”.
- Assess effects of intervention.
- Preoperative evaluation.
- Assessment of “fitness” to participate in various recreational or work related activities.
- Assess the impact of work place exposure on airway/lung function.
What do we measure from FVC?
The peak inspiratory flow is an instantaneous flow rate.
Describe static lung volumes and TLC tests?
Measure all static volumes and capacities of the lung: plethysmography, He dilution, and N2 wash out. Can;t measure residual volume without one of these techniques.
Describe static lung volumes and TLC indications?
Measurements of static lung volumes are used to establish or confirm a diagnosis of “restrictive” ventilatory defect.
Describe a plethysmography?
The principle of measuring thoracic gas volume (Vtg) using a body plethysmograph is based on Boyle’s law: P1xV1 = P2xV2.
Describe Helium dilution?
The He dilution method for measuring FRC (and TLC) uses the conservation of mass principle to measure the total volume of gas in the lung: C1xV1 = C2xV2. Only measures the volume of gas that makes contact with the mouth.
Describe nitrogen wash-out?
Measure all the nitrogen in your lungs. Know that the nitrogen of composition of nitrogen is around 79%. If we know the total amount of nitrogen that comes out and knows the concentration at the start, then use C1xV1 = C2xV2.
Describe alveolar-capillary diffusion assessment?
Use single-breath carbon monoxide diffusing capacity (Dlco). It evaluates the transfer of gas from the air spaces into the pulmonary capillaries.
Describe the indications of alveolar-capillary diffusion assessment?
- Evaluation and follow-up parenchymal lung disease.
- Differentiating among chronic bronchitis, emphysema and asthma.
- Evaluation of pulmonary involvement in systemic disease.
- prediction of arterial desaturation during exercise in some patients wiht lung disease.
Why do you use Carbon Monoxide?
It follows the same diffusion path as oxygen. the rate of diffusion is much lower than oxygen or carbon dioxide. The amount of CO transported across alveolar capillary membrane is DIFFUSION LIMITED and during the test CO never equilibrates with pulmonary capillary plasma. As Hb binds avidly to CO the concentration of CO in the pulmonary capillary plasma can be considered to be zero.
Describe the bronchodilator response test?
The degree to which bronchodilators can ameliorate the effect of airway obstruction can be assessed with PFTs. Reversibility is usually indicate by an increase in FEV1 of 12-15% and an increase in FEV1 of 200mL or greater.
