Effects of two inhaled corticosteroid/long-acting beta-agonist combinations on small-airway dysfunction in mild asthmatics measured by impulse oscillometry

Oscillometry of the respiratory system: a translational opportunity not to be missed

Airway oscillometry has become the de facto standard for quality assessment of lung physiology in laboratory animals and has demonstrated its usefulness in understanding diseases of small airways. Nowadays, it is seeing extensive use in daily clinical practice and research; however, a question that remains unanswered is how well physiological findings in animals and humans correlate? Methodological and device differences are obvious between animal and human studies. However, all devices deliver an oscillated airflow test signal and output respiratory impedance. In addition, despite analysis differences, there are ways to interpret animal and human oscillometry data to allow suitable comparisons. The potential with oscillometry is its ability to reveal universal features of the respiratory system across species, making translational extrapolation likely to be predictive. This means that oscillometry can thus help determine if an animal model displays the same physiological characteristics as the human disease. Perhaps more importantly, it can also be useful to determine whether an intervention is effective as well as to understand if it affects the desired region of the respiratory system, e.g., the periphery of the lung. Finally, findings in humans can also inform preclinical scientists and give indications as to what type of physiological changes should be observed in animal models to make them relevant as models of human disease. The present article will attempt to demonstrate the potential of oscillometry in respiratory research, an area where the development of novel therapies is plagued with a failure rate higher than in other disease areas.

Lung Function Assessment by Impulse Oscillometry in Adults

Over the past decades, impulse oscillometry (IOS) has gained ground in the battery of pulmonary function tests. Performing the test requires minimal cooperation of the patient; therefore, it is a useful tool, especially in evaluating lung mechanics in children, elderly patients, and those who cannot perform spirometry. Oscillometry has also been used in both clinical and research departments. Studies were published mainly in asthma regarding detection of bronchodilator response and the therapeutic response to different drugs. Furthermore, it has been shown to be a sensitive technique to evaluate disease control. Other studied diseases were COPD, interstitial lung diseases, small airway disease, impairment of lung function due to exposure to occupational hazards or smoking, central airways obstruction, cystic fibrosis, monitoring lung mechanics during mechanical ventilation and sleep, neuromuscular diseases, lung transplant, and graft function. The aim of this review is to present the utility of oscillometry on the previously mentioned clinical fields.

Comparison of two devices for respiratory impedance measurement using a forced oscillation technique: basic study using phantom models

Since commercial forced oscillation technique (FOT) devices became available, they have been widely used for physiological assessments, mainly of obstructive lung diseases. However, it is not known whether the impedance values measured with different devices are identical. In this study, two FOT devices-the impulse oscillometry system (IOS) and the MostGraph (MG)-were compared using phantom models. The resistance values varied up to 10% from estimated values in both devices. Additionally, there was a difference in frequency dependence for the resistance between the devices. The reactance values measured with MG were higher than those measured with IOS. The effects of ventilation on the measured impedance values were higher for IOS than for MG, especially at lower frequencies. We concluded that the devices do not always generate identical impedance values. Thus, differences between the devices should be taken into consideration when evaluating clinical data.