Advancing Pulmonary Function Testing at Valley: New Standards and Equipment

New Equipment

Valley’s Respiratory Services is upgrading its PFT booths this week; the respiratory therapists will be using the new equipment starting July 22, announced Stefanie Núñez, MD, Pulmonary, Critical Care & Sleep Medicine. The new equipment from MedGraphics is notable for having no weight limitations, addressing a significant issue with the previous equipment. This improvement ensures that all patients, regardless of weight, can undergo comprehensive respiratory testing.

Updated Reference Standards

One of the most critical changes is the adoption of the Global Lung Initiative (GLI) reference equations. The GLI standards, which are race-neutral, represent a significant shift from previous reference equations. By incorporating data from diverse racial and ethnic groups collected over the past two decades, these new standards aim to provide more accurate and equitable assessments of lung function across different demographics.

The standards will also change how results are interpreted by moving from a percent-predicted method to a Z-score method, which considers the upper and lower limits of normal based on standard deviations from the mean. This change aims to improve diagnostic accuracy, potentially altering previous diagnoses. "It's possible that in any given patient, a PFT previously called normal may now be abnormal, and vice versa, especially for older or non-Caucasian patients," Dr. Núñez explained. This enhancement will help ensure that patients with lung diseases are correctly identified and treated.

Ordering PFTs and Result Interpretation

The process for ordering PFTs in Epic remains the same. However, the interpretation template will now include the new explanatory information below. If you have any questions, please contact Dr. Núñez.

All studies are conducted according to the ATS/ERS 2022 guidelines.  Normative spirometry values utilize GLI (Global Lung Function Initiative) - Global 2022 reference equations, which are race-neutral. Normative lung volume and diffusion capacity values utilize GLI reference equations (published in 2021 and 2017, respectively). Lung volumes are measured by body plethysmography.  The DLCO is calibrated with a DLCO simulator, test gas analysis, and weekly bio-calibration. All studies meet or exceed the guideline requirements for reproducibility and quality unless otherwise noted.

Interpretation is based on lower and upper limit of normal (LLN/ULN = 5^th to 95^th percentile) values and standard deviation using Z-scores as follows:

A significant degree of uncertainty in interpretation exists, especially near the LLN (lower limit of normal).

PFTs alone should not be used to diagnose a specific pathological condition. The lack of a response to bronchodilator in a laboratory does not preclude its use in the appropriate clinical setting, nor does it necessarily rule out reactive airways disease.