CHEST Immersion Severe Asthma May 29-30, 2024-PFT

PFT_Spiro-Decato

Pdf Summary

Dr. Thomas W. DeCato, Medical Director of Pulmonary Function Testing, discusses the principles and clinical interpretation of spirometry, diffusing capacity, and lung volumes. Spirometry measures airflow limitations, with forced vital capacity (FVC) and forced expired volume in one second (FEV1) indicating obstruction or restriction. The flow-volume loop helps visualize airflow patterns. Obstruction occurs when airflow is limited during expiration due to factors like reduced elastic recoil or increased airway resistance. Reference values are compared based on age, sex, height, and race/ethnicity. The Global Lung Initiative provides recommended reference values for spirometry, diffusing capacity, and lung volumes.<br /><br />Valid spirometry requires acceptability and repeatability criteria to ensure accuracy. Reporting spirometry involves recording the highest acceptable values, using the highest FEV1/FVC ratio, and presenting data in a standardized format. Impairment severity is graded based on Z-scores.<br /><br />Diffusing capacity (DLCO) measures gas transfer in the lung, reflecting alveolar-capillary surface area. DLCO can be simplified into transfer properties involving surface area, thickness, and hemoglobin factors. The single-breath DLCO test involves specific inhalation and exhalation steps.<br /><br />Lung volumes are measured using various methods like plethysmography or inert gas dilution, providing essential information for diagnosing restriction, hyperinflation, or air trapping. Reporting lung volumes follows established standards. Overall, these pulmonary function tests play a crucial role in evaluating respiratory function and diagnosing respiratory conditions.

Keywords

Pulmonary Function Testing

Spirometry

Diffusing Capacity

Lung Volumes

Forced Vital Capacity

Forced Expiratory Volume in One Second

Flow-Volume Loop

Obstruction

Global Lung Initiative

DLCO