Respiratory input impedance measurement: Forced oscillation methods

Abstract

The paper reviews how forced oscillation techniques (FOT) for measuring respiratory input impedance Zrs,in have recently been used in clinical applications. Zrs,in is clinically relevant, as it provides data on both the resistive, Rrs, and nonresistive, Xrs, components of the respiratory system. Additionally, when excitatory test signals extending into low- (<4 Hz) or high-frequency (>100 Hz) ranges are used, reliable partitioning of lung tissue from airway components is feasible. Adult and paediatric studies examining the use of Zrs,in for routine lung-function assessment, sleep and mechanical ventilation are reviewed. For clinicians, Zrs,in repeatable and sensitive to airway resistance. It is helpful for assessing unco-operative and severely obstructed patients, for monitoring mechanics during artificial ventilation and for tracking airway closure during sleep studies. For paediatricians, longitudinal studies of the growth and development of the respiratory system can also be made using Zrs,in. Forced oscillation techniques, however, require further standardisation, and Zrs,in is limited by upper-airway shunt artifacts. In conclusion, measurement of Zrs,in using FOT is an important and sophisticated non-invasive lung-function test, showing good potential for future clinical applications.

Eşeklerde Solunum Ultrason Pletismografisinin Gözlemlenmesi Üzerine Bir Çalışma

“…Moreover, PFT appeared not a very sensitive tool for detecting smaller changes in diseased airways [10] . Thus, alternative systems to measure changes in lung function parameters are being developed for horse since more than two decades, but most of them are still under study [11][12][13][14][15] or interest in the methods was lost.…”

Forced Oscillation Technique in the Detection of Smoking-Induced Respiratory Changes

“…This short review is focused on the use of FOT in the clinical diagnostic of COPD, addressing only the most basic concepts, and the reader is referred for more detailed information to other review and monograph articles (Peslin and Fredberg, 1986;Macleod and Birch, 2001;Oostveen et al, 2003;Marchal and Hall, 2010;Bates et al, 2011;Kaczka and Dellacà 2011).…”

“…We now know that an impulse is the least reliable and desirable excitation waveform to apply for system identification because of signal-to-noise limitations over the bandwidth of interest (La Prad et al, 2008;Pintelon and Schoukens, 2001). The highest possible signal-to-noise ratio is produced using pseudorandom noise (Macleod and Birch, 2001;Oostveen et al, 2003;Bates et al, 2011), which is a periodic signal designed specifically to include only a designated set of desired frequency components, each represented by a precisely defined amplitude and phase.…”

“…IOS differs from classical FOT in the data processing and the parameters used to interpret the raw data (Mac Leod and Birch, 2001;Hellinckx et al, 2001). Several technical and clinical validation issues also remain to be assessed for IOS techniques (MacLeod and Birch, 2001;Hellinckx et al 2001;Ritz et al, 2002). Although the signal used in IOS has the practical advantage of being relatively easy to generate, it has significant disadvantages in terms of energy distribution .…”

“…The method is simple and requires only passive co-operation and no forced expiratory maneuvers. Another important advantage, particularly in pathophysiological research, is that FOT can be used to provide information on the mechanical characteristics of the respiratory system that is complementary to the information provided by spirometry Macleod and Birch, 2001;Oostveen et al, 2003;Bates et al, 2011;Kaczka and Dellacà 2011). This technique has the potential to greatly increase our knowledge regarding the pathophysiology of smoking, as well as to help in the clinical diagnosis of early smoking-induced respiratory alterations and COPD (Faria et al, 2009;Faria et al, 2010;Silva et al, 2011;Postma et al, 2012;Amaral et al, 2012).…”