Detection of flow limitation during tidal breathing by the interruptor technique

Hage, René; Aerts, Joachim; Verbraak, A. F. M.; Berg, Benno van den; Bogaard, J. M.

doi:10.1183/09031936.95.08111910

Cited by 10 publications

(14 citation statements)

References 14 publications

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“…During an interruption of the expiratory flow, the flow limiting segment will be abolished, after re-opening of the interrupter valve flow limitation will re-appear, resulting in an overshoot in expiratory flow [3,19,20,24]. In healthy subjects this method has been validated and quantified during forced expiration [24,37].…”

Section: Discussionmentioning

confidence: 99%

“…The dynamic properties of the interrupter device have previously been studied using a constant flow generator. Using this technique small oscillations were detected of the same magnitude, frequency, and pattern during opening and closing of the interrupter valve, which could be corrected for [20].…”

Section: Resistormentioning

confidence: 99%

“…After opening of the valve, flow limitation was assumed to be present when the opening transient clearly exceeded the closing transient [19,20]. To quantify the analysis of the data obtained with the interrupter technique the spike area was determined by back extrapolation of the flow during the interval 100±250 ms after reopening of the interrupter (Fig.…”

Section: Resistormentioning

confidence: 99%

“…Flow limitation is assumed present when after a brief occlusion of the airway, a spike flow superimposed on the ongoing mouth flow is detected. In spontaneously breathing patients this method has been quantified and validated [20]. In mechanically ventilated patients the interrupter method has only been used in a qualitative way [3,19].…”

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Detection of flow limitation in mechanically ventilated patients

et al. 2001

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Section: Discussionmentioning

confidence: 99%

Section: Resistormentioning

confidence: 99%

Section: Resistormentioning

confidence: 99%

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Detection of flow limitation in mechanically ventilated patients

et al. 2001

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“…An extreme case of nonlinearity which, to our knowledge, has not been much discussed so far in the context of forced-oscillation studies, is the occurrence of expiratory flow limitation (EFL) during the measurements. Yet EFL is not exceptional during spontaneous breathing in patients with severe airway obstruction (9,10); it is still more likely to occur during bronchomotor challenge and is a common finding in patients mechanically ventilated for acute respiratory failure (6,8,27,28). In the latter situation, large variations of Zrs during the respiratory cycle have been reported, with much lower values of the imaginary part (Im) of Zrs during the expiratory phase than during the inspiratory phase (20).…”

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Effect of expiratory flow limitation on respiratory mechanical impedance: a model study

Peslin

Farré²,

Rotger³

et al. 1996

Journal of Applied Physiology

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Peslin, R., R. Farré , M. Rotger, and D. Navajas. Effect of expiratory flow limitation on respiratory mechanical impedance: a model study. J. Appl. Physiol. 81(6): 2399-2406, 1996.-Large phasic variations of respiratory mechanical impedance (Zrs) have been observed during induced expiratory flow limitation (EFL) (M. Vassiliou, R. Peslin, C. Saunier, and C. Duvivier. Eur. Respir. J. 9: 779-786, 1996). To clarify the meaning of Zrs during EFL, we have measured from 5 to 30 Hz the input impedance (Zin) of mechanical analogues of the respiratory system, including flow-limiting elements (FLE) made of easily collapsible rubber tubing. The pressures upstream (Pus) and downstream (Pds) from the FLE were controlled and systematically varied. Maximal flow (V max) increased linearly with Pus, was close to the value predicted from wave-speed theory, and was obtained for Pus-Pds of 4-6 hPa. The real part of Zin started increasing abruptly with flow (V ) .85% V max and either further increased or suddenly decreased in the vicinity of V max. The imaginary part of Zin decreased markedly and suddenly above 95% V max. Similar variations of Zin during EFL were seen with an analogue that mimicked the changes of airway transmural pressure during breathing. After pressure and V measurements upstream and downstream from the FLE were combined, the latter was analyzed in terms of a serial (Zs) and a shunt (Zp) compartment. Zs was consistent with a large resistance and inertance, and Zp with a mainly elastic element having an elastance close to that of the tube walls. We conclude that Zrs data during EFL mainly reflect the properties of the FLE. respiratory mechanics; mechanical analogue; maximal expiratory flow; forced oscillations; airway wall elasticity RESPIRATORY IMPEDANCE (Zrs) measurements by forced oscillations (3) are increasingly used to assess respiratory mechanics in physiological and clinical applications. Useful features of the method are that it does not require active cooperation from the patient and, contrary to spirometric investigations (7, 17), does not alter the bronchomotor tone (23). This makes the method particularly adequate for studying airway response to bronchomotor drugs (11,14,29,31,32). A recent and promising application is the study of respiratory mechanics during mechanical ventilation (18,20), where other approaches are either invasive and/or require muscular relaxation and/or require special flow (V ) patterns.Impedance measurements relate the amplitude and phase of small sinusoidal pressure swings applied to the respiratory system to those of the resulting V oscillations superimposed on the respiratory V . The impedance and its frequency dependence are interpreted with the use of models that usually postulate that the respiratory system is linear. This is clearly the exception rather than the rule in patients with severe airway obstruction, in which case the impedance, like any other mechanical parameter, will vary with the amplitude and pattern of breathing. Nonlinearity of the system may also be resp...

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Chronic Obstructive Pulmonary Disease

Brusasco

Martínez

2014

Comprehensive Physiology

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COPD is characterized by airflow limitation that is not fully reversible. The morphological basis for airflow obstruction results from a varying combination of obstructive changes in peripheral conducting airways and destructive changes in respiratory bronchioles, alveolar ducts, and alveoli. A reduction of vascularity within the alveolar septa has been reported in emphysema. Typical physiological changes reflect these structural abnormalities. Spirometry documents airflow obstruction when the FEV 1 /FVC ratio is reduced below the lower limit of normality, although in early disease stages FEV 1 and airway conductance are not affected. Current guidelines recommend testing for bronchoreversibility at least once and the postbronchodilator FEV 1 /FVC be used for COPD diagnosis; the nature of bronchodilator response remains controversial, however. One major functional consequence of altered lung mechanics is lung hyperinflation. FRC may increase as a result of static or dynamic mechanisms, or both. The link between dynamic lung hyperinflation and expiratory flow limitation during tidal breathing has been demonstrated. Hyperinflation may increase the load on inspiratory muscles, with resulting length adaptation of diaphragm. Reduction of exercise tolerance is frequently noted, with compelling evidence that breathlessness and altered lung mechanics play a major role. Lung function measurements have been traditionally used as prognostic indices and to monitor disease progression; FEV 1 has been most widely used. An increase in FVC is also considered as proof of bronchodilatation. Decades of work has provided insight into the histological, functional, and biological features of COPD. This has provided a clearer understanding of important pathobiological processes and has provided additional therapeutic options.

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Detection of flow limitation during tidal breathing by the interruptor technique

Cited by 10 publications

References 14 publications

Detection of flow limitation in mechanically ventilated patients

Detection of flow limitation in mechanically ventilated patients

Effect of expiratory flow limitation on respiratory mechanical impedance: a model study

Chronic Obstructive Pulmonary Disease

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