The forced oscillation technique in clinical practice: methodology, recommendations and future developments. E. Oostveen, D. MacLeod, H. Lorino, R. Farre´ , Z. Hantos, K. Desager, F. Marchal, on behalf of the ERS Task Force on Respiratory Impedance Measurements. #ERS Journals Ltd 2003. ABSTRACT: The forced oscillation technique (FOT) is a noninvasivemethod with which to measure respiratory mechanics. FOT employs small-amplitude pressure oscillations superimposed on the normal breathing and therefore has the advantage over conventional lung function techniques that it does not require the performance of respiratory manoeuvres. The present European Respiratory Society Task Force Report describes the basic prin- ciple of the technique and gives guidelines for the application and interpretation of FOT as a routine lung function test in the clinical setting, for both adult and paediatric populations. FOT data, especially those measured at the lower frequencies, are sensitive to airway obstruction, but do not discriminate between obstructive and restrictive lung disorders. There is no consensus regarding the sensitivity of FOT for bronchodilation testing in adults. Values of respiratory resistance have proved sensitive to bronchodilation in children, although the reported cutoff levels remain to be cone rmed in future studies. Forced oscillation technique is a reliable method in the assessment of bronchial hyper- responsiveness in adults and children. Moreover, in contrast with spirometry where a deep inspiration is needed,forced oscillation techniquedoes not modifytheairway smooth muscle tone. Forced oscillation technique has been shown to be as sensitive as spirometry in detecting impairments of lung function due to smoking or exposure to occupational hazards. Together with the minimalrequirement for the subject 9s cooperation, this makes forced oscillation technique an ideal lung function test for epidemiological and e eld studies. Novel applications of forced oscillation technique in the clinical setting include the monitoring of respiratory mechanics during mechanical ventilation and sleep.

https://erj.ersjournals.com/content/erj/22/6/1026.full.pdf

The forced oscillation technique in clinical practice: methodology, recommendations and future developments

Conventional methods of lung function testing provide measurements obtained during specific respiratory actions of the subject In contrast, the forced oscillation technique (FOT) determines breathing mechanics by superimposing small external pressure signals on the spontaneous breathing of the subject FOT is indicated as a diagnostic method
to obtain reliable differentiated tidal breathing analysis Because FOT is performed without closure of a valve connected to the mouthpiece, and without maximal or forced respiratory manoeuvres, it is unlikely that FOT itself will alter airways smooth muscle tone
FOT utilises the external applied pressure signals and their resultant flows to determine lung mechanical parameters These pressure–flow relationships are largely distinct from the natural pattern of individual respiratory flows, so that measured FOT results are, for the most part, independent of the underlying respiratory pattern Therefore, oscillometry minimises demands on the patient and requires only passive cooperation of the subject: maintenance of an airtight seal of the lips around a mouthpiece and breathing normally
through the measuring system with a nose-clip occluding the nares Potential
applications of oscillometry include paediatric, adult and geriatric populations, comprising diagnostic clinical testing, monitoring of therapeutic regimens, and epidemiological evaluations, independent of severity of lung disease Oscillometry is also applicable to veterinary medicine
The last two main sections Relevance of oscillometry in clinical practice and
Oscillometry in the clinical pulmonary laboratory emphasise clinical aspects of
application and interpretation of FOT rather than methodological details and
technological solutions, which are discussed in the two sections that follow immediately below Clinical application of FOT does not require mastery of the mathematical infrastructure of the technical methodology, and readers interested in the clinical use of
FOT may find it more useful to begin with these clinical sections and refer subsequently to methodological and technological details

Forced oscillation technique and impulse oscillometry

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update.

Changes in respiratory mechanics with increasing degrees of airway obstruction in COPD : Detection by forced oscillation technique

Detection of changes in respiratory mechanics due to increasing degrees of airway obstruction in asthma by the forced oscillation technique

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- ( 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.

D MacLeod

Papers

Respiratory input impedance measurement: Forced oscillation methods