A Comprehensive Review of Pulmonary Function Tests and their Clinical Applications

Robert Dyane^*
*Correspondence: Robert Dyane, Department of Veterinary Pathobiology, Texas A&M University, College Station, USA, Email:

Introduction

Pulmonary Function Tests (PFTs) are a group of non-invasive diagnostic procedures used to assess the functional capacity of the respiratory system. These tests play a crucial role in the diagnosis, monitoring, and management of various respiratory conditions, such as asthma, Chronic Obstructive Pulmonary Disease (COPD), interstitial lung diseases, and restrictive lung disorders. In this comprehensive review, we will delve into the different types of PFTs, their methodologies, and their clinical applications, shedding light on their importance in modern healthcare. Pulmonary Function Tests are a collection of tests that provide objective measurements of lung function. The primary parameters evaluated include lung volumes, airflow rates, and gas exchange efficiency. PFTs are typically performed using specialized equipment, and the data obtained helps healthcare professionals assess the overall health of the lungs, diagnose respiratory diseases, determine the severity of lung disorders, and monitor the effectiveness of treatments.

Description

Spirometry is the most commonly performed PFT. It measures the volume and flow rate of inhaled and exhaled air, helping to determine Vital Capacity (VC), Forced Vital Capacity (FVC), forced expiratory volume in 1 second (FEV1), and the FEV1/FVC ratio. These parameters are crucial in diagnosing and monitoring obstructive and restrictive lung disorders. PEF measures the maximum flow of air that can be rapidly exhaled after a deep inhalation. It is an essential tool for diagnosing and monitoring asthma, as well as assessing the response to bronchodilator therapy. These tests measure specific lung volumes, such as Total Lung Capacity (TLC), Residual Volume (RV), Functional Residual Capacity (FRC), and Inspiratory Capacity (IC). Assessing lung volumes is vital in diagnosing restrictive lung diseases and assessing the effectiveness of treatment [1].

DLCO measures the ability of the lungs to transfer gases, specifically carbon monoxide, from the alveoli to the bloodstream. It is useful in diagnosing and evaluating interstitial lung diseases and pulmonary vascular disorders. Spirometry involves having the patient breathe through a mouthpiece attached to a spirometer. The patient is asked to take a deep breath and then exhale forcefully and rapidly. The spirometer records the volume of air expelled and the flow rate throughout the exhalation. Lung volumes and capacities are measured using various techniques, such as helium dilution, nitrogen washout, and body plethysmography. These methods involve the patient breathing specific gas mixtures, and the changes in gas concentrations are used to calculate the lung volumes [2].

DLCO is measured by having the patient inhale a small amount of carbon monoxide and then holding their breath for a brief period. The reduction in carbon monoxide concentration after breath-holding is used to calculate the diffusion capacity.PFTs are crucial in diagnosing various respiratory conditions. For example, in asthma, spirometry can reveal a reduced FEV1/FVC ratio and demonstrate reversibility with bronchodilators. In COPD, spirometry shows reduced FEV1 and FEV1/FVC ratio, indicating persistent airflow limitation. Lung volumes can help diagnose restrictive lung diseases, and DLCO is essential in diagnosing interstitial lung diseases. PFTs play a significant role in monitoring the progression of respiratory diseases. Regular assessments of lung function help healthcare providers determine the effectiveness of treatment plans and make adjustments when necessary. Patients with chronic conditions, such as COPD, can benefit greatly from regular PFTs to track their lung function decline and adjust therapeutic strategies [3]. Before major surgeries, especially those involving the chest or general anesthesia, PFTs are often performed to assess lung function and predict potential complications during and after surgery. This preoperative evaluation helps guide the surgical team in planning the procedure and managing anesthesia.

PFTs are used in medicolegal settings to assess respiratory impairment and disability, particularly in cases involving workers' compensation claims or disability benefits. The objective data provided by PFTs can be crucial in determining the level of respiratory disability and its impact on a person's ability to work and perform daily activities. PFTs are used to evaluate the response to various respiratory therapies, such as bronchodilators and corticosteroids. By comparing lung function before and after treatment, healthcare professionals can gauge the effectiveness of interventions and adjust treatment plans accordingly [4].

A multicenter, non-interventional partner study with 954 seriously ill Coronavirus patients demonstrated that inhaled corticosteroids significantly decreased the death rate. In a randomised, open-label Stage 2 study involving 61 patients with mild to moderate Coronavirus illness, it was discovered that inhaled ciclesonide significantly more effectively killed SARS-CoV-2 than the conventional treatment. In a multicenter, open-label, multi-arm, randomised, controlled, multi-stage study involving more than 4700 participants, it was discovered that inhaled budesonide could lengthen recovery time and reduce the risk of mortality. From these tests, it is extremely likely that a more effective compelling treatment for Coronavirus is possible by inhaled medication than oral treatment. One of the key takeaways from this review is the importance of early and accurate diagnosis of respiratory diseases.

PFTs play a central role in identifying conditions like asthma, COPD, interstitial lung diseases, and others, allowing for timely intervention and appropriate treatment. Furthermore, they aid in differentiating between obstructive and restrictive patterns, enabling healthcare providers to tailor therapies specific to each patient's condition. The advancements in pulmonary function testing, such as Impulse Oscillometry (IOS), Multiple Breath Washout (MBW), and exhaled Nitric Oxide (eNO) measurement, hold great promise for refining respiratory assessments. These novel techniques provide additional insights into airway resistance, reactance, ventilation inhomogeneity, and airway inflammation, potentially improving diagnostic accuracy and disease monitoring. Special populations, such as pediatric and elderly patients, present unique challenges in conducting PFTs. Age-specific reference values and adaptation of testing techniques are essential to account for age-related changes in lung function accurately [5].

Conclusion

Pulmonary Function Tests are indispensable tools in modern respiratory medicine. By providing objective measurements of lung function, they aid in the diagnosis, monitoring, and management of various respiratory conditions. Spirometry, peak expiratory flow measurements, lung volume assessments, and diffusion capacity tests are all valuable components of PFTs. Their clinical applications span from diagnosing respiratory diseases to guiding treatment strategies and assessing disability. As technology and research advance, these tests will continue to evolve, further enhancing their role in improving patient outcomes and overall respiratory health.

Acknowledgement

None.

Conflict of Interest

The authors declare that there is no conflict of interest.

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