Asynchrony and cyclic variability in pressure support noninvasive ventilation

Achour, L.; Letellier, Christophe; Cuvelier, A.; Vérin, Eric; Muir, Jean-François

doi:10.1016/j.compbiomed.2006.12.005

Cited by 21 publications

(18 citation statements)

References 23 publications

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“…Suboptimal ventilation was more common at the start of ventilation treatment; therefore, the number of traces and PG/PSG required, and consequently the number of modifications made, was higher in that period. The better ventilation performance observed in patients assessed at a later period may reflect greater clinical stability or a ''training effect'' [22], but may also reflect that many of these patients had undergone monitoring at the start of the NIV, making early intervention possible. The abnormalities were less common when an FM was used, but this difference was only significant in the acute phase.…”

Section: Discussionmentioning

confidence: 99%

Evaluating noninvasive ventilation using a monitoring system coupled to a ventilator: a bench-to-bedside study

Rabec¹,

Georges²,

Kabeya³

et al. 2009

Eur Respir J

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Empirically determined noninvasive ventilation (NIV) settings may not achieve optimal ventilatory support. Some ventilators include monitoring modules to assess ventilatory quality. We conducted a bench-to-bedside study to assess the ventilatory quality of the VPAP TM IIIResLink TM (ResMed, North Ryde, Australia).We tested the accuracy of minute ventilation (MV) and leak calculations given by VPAP TM IIIResLink TM compared to those measured by a bench model at varied leak levels and ventilator settings. We systematically assessed NIV efficacy using this system from 2003 to 2006. Ventilation was considered inadequate if leak (.24 L?min -1 ), continuous desaturation (.30% of the trace) or desaturation dips (.3%) were present. On the bench test, both methods were highly correlated (r50.947, p.0.0001 and r50.959, p,0.0001 for leak and MV, respectively). We performed 222 assessments in 169 patients (aged 66.42¡16 yrs, 100 males). Abnormalities were detected on 147 (66%) out of 222 occasions. Leak was the most common abnormality (34.2%) followed by desaturation dips (23.8%). The most effective therapeutic solutions were a chin strap if leak was detected (61.2%) and expiratory positive airway pressure increase for desaturation dips (59.5%). In 15.7% of cases, when abnormalities persisted, a polygraphy was performed.The systematic use of this device enables NIV to be optimised, limiting the indication of sleep studies to complex cases. KEYWORDS: Bench testing, bi-level positive airway pressure, clinical evaluation, monitoring, noninvasive ventilation, respiratory failure N oninvasive ventilation (NIV) has been demonstrated to be effective treatment in respiratory failure. In some cases, however, the clinical results may be less than expected, despite using the correct technique. When NIV is initiated, the ventilator settings are determined empirically based on clinical evaluation of underlying disease, patient tolerance when awake, and diurnal blood gas variations [1]. However, NIV is predominantly applied at night [2], when profound ventilatory changes may occur, particularly in patients with respiratory failure [3]. Such changes include modifications of ventilatory control, upper airway patency and respiratory muscle recruitment. Consequently, modulating NIV settings during the day and underestimating these physiological differences may lead to suboptimal patientventilator interaction that reduces NIV efficacy.Moreover, NIV uses a non-hermetic technique, which poses the possible risk of leak. Leakage may be absent or minimal when the patient is awake and may worsen during sleep as a result of the loss of voluntary control and decreased muscle tone. Thus, NIV settings chosen empirically on daytime evaluation may not predict optimal nocturnal ventilatory support. Consequently, NIV effectiveness may be more correctly assessed by sleep studies than through daytime assessment [1]. Ideally this requires complete polysomnography (PSG) or ventilatory polygraphy (PG) at the time of initiation to NIV. However, it is n...

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Section: Discussionmentioning

confidence: 99%

Evaluating noninvasive ventilation using a monitoring system coupled to a ventilator: a bench-to-bedside study

Rabec¹,

Georges²,

Kabeya³

et al. 2009

Eur Respir J

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“…Nevertheless, the linear regression obtained from their data cannot be used since their measures were performed in subjects under exercise, contrary to patients who are commonly ventilated during their sleep. We thus retained a linear dependence roughly matching with T I = 1.5 s for f v = 10 cpm and T I = 1.0 s for f v = 30 cpm, as observed in previous studies [26,27]. The ratio T I T tot thus depends on the ventilatory frequency according to…”

Section: Inspiratory and Expiratory Durationsmentioning

confidence: 53%

Realistic human muscle pressure for driving a mechanical lung

Fresnel

Muir

Letellier

2014

EPJ Nonlinear Biomed Phys

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Background: An important issue in noninvasive mechanical ventilation consists in understanding the origins of patient-ventilator asynchrony for reducing their incidence by adjusting ventilator settings to the intrinsic ventilatory dynamics of each patient. One of the possible ways for doing this is to evaluate the performances of the domiciliary mechanical ventilators using a test bench. Such a procedure requires to model the evolution of the pressure imposed by respiratory muscles, but for which there is no standard recommendations. Methods:In this paper we propose a mathematical model for simulating the muscular pressure developed by the inspiratory muscles and corresponding to different patient ventilatory dynamics to drive the ASL 5000 mechanical lung. Our model is based on the charge and discharge of a capacitor through a resistor, simulating contraction and relaxation phases of the inspiratory muscles.Results: Our resulting equations were used to produce 420 time series of the muscle pressure with various contraction velocities, amplitudes and shapes, in order to represent the inter-patient variability clinically observed. All these dynamics depend on two parameters, the ventilatory frequency and the mouth occlusion pressure. Conclusion:Based on the equation of the respiratory movement and its electrical analogy, the respiratory muscle pressure was simulated with more consistency in regards of physiological evidences than those provided by the ASL 5000 software. The great variability in the so-produced inspiratory efforts can cover most of realistic patho-physiological conditions.

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“…It has been found that the Shannon entropy S P is strongly correlated to the rate of non-triggered cycles. In a previous study (Achour et al 2007), we found that an asynchronism frequency below 10% was not relevant for ventilatory comfort. Such a rate corresponds to a Shannon entropy slightly less than 1.…”

Section: Dynamical Analysismentioning

confidence: 99%

“…For instance, the healthy subject S 12 had 41% of ineffective triggerings with an antibacterial filter, but less than 4.6% when this filter was removed. Indeed, the filter can be viewed as a 64% increase of the threshold value for triggering the ventilator (Achour et al 2007). Phase portraits were reconstructed from the airflow in both cases (figure 6).…”

Section: Dynamical Analysismentioning

confidence: 99%

Recurrence plots for dynamical analysis of non-invasive mechanical ventilation

Letellier

Rabarimanantsoa

Achour

et al. 2007

Phil. Trans. R. Soc. A.

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Quantifiers were introduced to convert recurrence plots into a statistical analysis of dynamical properties. It is shown that the Shannon entropy, if properly computed, increases as the chaotic regime is developed as expected. Recurrence plots and a new estimator for the Shannon entropy are then used to identify asynchronisms in noninvasive mechanical ventilation. It is thus shown that the phase coherence-easily identified using a Shannon entropy-is relevant in the quality of the mechanical ventilation. In particular, some patients with chronic respiratory diseases or healthy subjects can have a high rate of asynchronisms but a regular breathing rhythm.

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Asynchrony and cyclic variability in pressure support noninvasive ventilation

Cited by 21 publications

References 23 publications

Evaluating noninvasive ventilation using a monitoring system coupled to a ventilator: a bench-to-bedside study

Evaluating noninvasive ventilation using a monitoring system coupled to a ventilator: a bench-to-bedside study

Realistic human muscle pressure for driving a mechanical lung

Recurrence plots for dynamical analysis of non-invasive mechanical ventilation

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