DLCO testing for COPD

Is DLCO an effective tool?

Chronic Obstructive Pulmonary Disease (COPD) impacts the lives of 15.7 million adults in the United States alone. COPD is also the fourth leading cause of death in the US. Worse yet – it’s estimated that several million Americans are currently living with COPD but have not been correctly diagnosed.

In recent years, spirometry has been used by respiratory health professionals as the primary tool in diagnosing COPD, as the presence of airflow obstruction is a key diagnosis criterion. More recently, the approach to COPD assessment has broadened from primary spirometry to include assessment of symptoms, impact on health status, quantitative assessment of emphysema by CT imaging, and risk of exacerbations.

The measurement of diffusing capacity of the lung for carbon monoxide or DLCO is a non-invasive and widely available diagnostic tool, but not commonly used in COPD assessment models.

A new paper, with data from the COPDGene Study, The Diffusion Capacity of Carbon Monoxide in the Assessment of COPD, was recently published in the CHEST Journal. Results from the study showed that reduced DLCO is associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema.

Nonetheless, the question remains – is DLCO testing an effective tool for assessing COPD? Let’s answer this question. In the information below, we’ll explain the facts about DLCO testing, why DLCO is important for assessing COPD, and introduce you to the NDD Medical Technologies line of PFT devices that deliver clear, quick, and accurate DLCO results.

age adjusted death rates for the 10 leading causes of death in 2016 - NDD - Spirometer - Spirometry
Data table. Number of deaths, percentage of total deaths, and age-adjusted death rates for the 10 leading causes of death in 2016: United States, 2015 and 2016 
SOURCE: NCHS, National Vital Statistics System, Mortality.

What is DLCO testing?

The most effective tools for assessing lung function are pulmonary function tests or PFT. While spirometry is the most common and widely used lung function test, it is not as effective in measuring complete lung health. This is where DLCO is crucial. DLCO is also known as the transfer factor. This measurement helps access the lung's ability to transfer gas from inspired air to the bloodstream, specifically the uptake of carbon monoxide (CO) per unit time / per mm of driving pressure of CO (or cc of CO/sec/mm of Hg).

Carbon monoxide (CO) has a high affinity for hemoglobin, and it follows the same pathway as that of oxygen to finally bind with hemoglobin. Inhaled CO is used for this test due to its high affinity for hemoglobin (200-250 times that of oxygen). Among other potential gases to be used for evaluating diffusing capacity, oxygen is not preferred since its uptake is limited by cardiac uptake and total body consumption. 

The test is non-invasive and simple for the patient to complete.

Why is DLCO important for assessing COPD?

The Genetic Epidemiology of COPD or COPDGene study provides the optimal environment to analyze and determine whether DLCO testing provides a gateway to diagnose COPD morbidity. Noted below is the criterion on which this study was completed.

  • BACKGROUND: Diffusing capacity of the lung for carbon monoxide (DLCO) is inconsistently obtained in patients with COPD, and the added benefit of DLCO testing beyond that of more common tools is unknown.
  • OBJECTIVE: The goal of this study was to determine whether lower DLCO is associated with increased COPD morbidity independent of emphysema assessed via spirometry and CT imaging.
  • METHODS: Data for 1,806 participants with COPD from the Genetic Epidemiology of COPD (COPDGene) study 5-year visit were analyzed, including pulmonary function testing, quality of life, symptoms, exercise performance, and exacerbation rates.
    • DLCO percent predicted was primarily analyzed as a continuous variable and additionally categorized into four groups: (1) DLCO and FEV1 > 50% (reference); (2) only DLCO # 50%; (3) only FEV1 # 50%; and (4) both # 50% predicted. Outcomes were modeled by using multivariable linear and negative binomial regression, including emphysema and FEV1 percent predicted among other confounders.
  • CONCLUSIONS: Impairment in DLCO was associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema. These findings suggest that DLCO should be considered for inclusion in future multidimensional tools assessing COPD.

The key findings noted in the publication of this study indicate that DLCO is one of the best correlates of emphysema in COPD. It further discovered that lower percent predicted DLCO was associated with increased COPD morbidity.

In other words – DLCO is a critical component that helps medical professionals provide a more accurate diagnosis of COPD, which allows for better treatment, patient-centric care, and respiratory therapy, and allowing them to live a higher quality of life.

As quoted from the study, “Specifically, DLCO measurement may provide information regarding the functional status and identify subgroups of patients who display diminished exercise performance or frequent exacerbations that are incompletely captured by existing indices.”

“Furthermore, it may provide a window into the interactions between vascular and pulmonary physiology, an area that should be further investigated. DLCO offers clinically important information beyond that obtained from spirometry and radiography and should be considered in characterizing and managing patients with COPD.”

Introducing the EasyOne Pro – Robust DLCO testing with user-friendly technology

Spirometry and DLCO measurements in the above mentioned COPDGene study were conducted by using the EasyOne Pro® (NDD Medical Technologies) following the American Thoracic Society (ATS)/European Respiratory Society guidelines, with standardization of protocols and quality control procedures across clinical sites.

NDD Medical Technologies offers a pair of potent PFT devices that deliver portable DLCO, lung volumes, and spirometry – showcasing multiple user-friendly tools, and a compact, lightweight design.

The EasyOne Pro® and EasyOne Pro® LAB are infused with NDD’s patented TrueFlow™ and TrueCheck™ technology, which eliminates the root sources of testing errors, removes the need for continual calibration, saves time, and is easier for clinicians and patients to use. Its compact design makes it a functional PFT for offices of any size and includes features that streamline the PFT process – without compromising the quality of results.

  • Point of care testing
    The days of sending patients to designated testing facilities for PFT examinations are over. The EasyOne Pro line of PFT devices can be operated in medical exam rooms, offices, and remote locations. Results are quick, accurate, and robust.
  • No more time-consuming calibration
    Older PFT devices and technology requires constant calibration – even between individual patient tests. With the EasyOne Pro and EasyOne Pro LAB, the system is calibrated and ready to use. This system can provide the technician with DLCO results in minutes. These features are possible due to NDD’s patented TrueCheck technology – which takes care of the essential quality control needed for gas analysis testing.
  • Customized commentator
    The integrated commentator permits clinicians to easily define standard comments and quickly add them to the patient's results. You can also select or deselect predefined comments, modify and edit comments, and insert custom notes in a matter of seconds.

EasyOne Pro and EasyOne Pro LAB are the only devices proven to be accurate for a lifetime for DLCO measurements. These solutions are easy to use, produce superior testing results, and are more affordable than traditional methods of lung measurement. If you’d like to learn more about the EasyOne Pro and EasyOne Pro LAB please click the product links below. 

Portable DLCO, Lung Volumes and Spirometry

Portable DLCO, MBW, Lung Volumes, LCI and Spirometry

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