PFT Study Guide 2022 new exam update guiding questions and answers Purpose of performing pulmonary function tests (PFTs) - - Functional *status* of the *lungs* - *How MUCH & how FAST GAS* can be moved into and out of the lungs - *Diffusion characteristics* of the alveolar-capillary membrane *the tests can dx. lung diseases & measure the severity of the disease* Contraindications include: - - pneumothorax (untreated) - hemoptysis - cardiovascular disease - cataract removal surgery (ocular pressure) Pulmonary function devices that collect and measure GAS volumes - - water sealed spirometer - bellows spirometer - dry-rolling-seal spirometer Lung volumes - how much air your lungs can hold Spirometry determines - how quickly you can move air in & out of your lungs Diffusing capacity - how well your lungs add oxygen & remove carbon dioxide Parameters to establish normal values for PFTs - -*G*ender -*H*eight -*R*ace - Age What is the most important factor influencing lung size and predicted values? - *Height* the taller the person, the larger are predicted lung volumes, flow rates, and diffusing capacity. Lung volumes and flow rates are affected typically when the BMI is greater than: - *BMI>30* as a person gains weight, lung volumes and flow rates do not changes until the person becomes obese (BMI>30) The instrument used primarily in PFT - Spirometer (for measuring routine *flows* & *volumes*) Standard equipment in a pulmonary function laboratory - - Spirometer - Gas analyzer - Body plethysmograph What is the volume of air inhaled and exhaled during quiet breathing? - tidal volume (Vt) Normal minute ventilation of an average person at rest - 4 to 12 L/min (depending of the size of the pt.) Why is proper coaching of the pt. during FVC maneuver extremely important? - *ERRONEOUS FVC* test results (most common) Restrictive lung disorders reduce FVC by - shrinking the lung (decrease in lung size) Obstructive lung disorders reduce FVC by - increase in RV (caused by air trapping) If measured FVC is significantly smaller than SVC, what is occurring? - air trapping What level of VC is associated with *increased risk of postoperative respiratory complications*? - <20>