The Nagoya Conference on System Design and Patient-Ventilator Interactions During Pressure Support Ventilation

MacIntyre, Neil R.; Nishimura, Masaji; Usada, Yutaka; Tokioka, Hiroaki; Takezawa, Jun; Shimada, Yasuhiro

doi:10.1378/chest.97.6.1463

Cited by 81 publications

(27 citation statements)

References 11 publications

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“…Patients with a f R greater than 40 breaths·min -1 were excluded from the study, since it has been suggested that during PSV the f R should be kept below that level [11,12]. All the measurements were performed at a constant inspiratory oxygen fraction (FI,O 2 ).…”

Section: Methodsmentioning

confidence: 99%

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies

Nava¹,

Bruschi²,

Fracchia³

et al. 1997

Eur Respir J

143

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The aim of this study was to evaluate whether pressure support ventilation (PSV) requires different diaphragmatic efforts and patient-ventilator matching, according to the underlying disease.Four groups of patients requiring PSV were studied: Group A, recovering from an episode of acute respiratory failure due to adult respiratory distress syndrome (ARDS); Group B, with postsurgical complications; and two subsets of chronic obstructive pulmonary disease (COPD) patients, with "normal" static compliance of the respiratory system (Cst,rs) (Group C), or elevated Cst,rs (Group D).Ventilatory pattern, transdiaphragmatic pressure (Pdi), the pressure-time product of the diaphragm (PTPdi), static (PEEPi,stat) and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn), Cst,rs and resistance of the total respiratory system (Rrs) were recorded. The matching between patient and ventilator was analysed, recording the number of "ineffective efforts" (inspiratory efforts not efficient enough to trigger a new ventilator cycle, despite a positive deflection in Pdi).A satisfactory blood gas equilibrium arterial oxygen saturation (Sa,O 2 >93%, with a pH >7.32) was obtained in the various groups with different levels of PSV. Minute ventilation was found to be significantly higher in Groups A and B, due to the longer expiratory time (t E) in the COPD groups. Group A (2 out of 7), Group B (3 out of 7), Group C (3 out of 5) patients showed sporadic "ineffective efforts". All Group D patients manifested continuous mismatching with the ventilator, so that the pressure-time product of the diaphragm per minute (PTPdi/min), reflecting the metabolic work of the diaphragm, was not different in the four groups. Tidal volume and the spontaneous inspiratory efforts were similar in the four groups, but the number of breaths delivered by the ventilator was significantly higher in Groups A and B.The application of different levels of pressure support ventilation in patients with acute respiratory failure due to different pathologies, led them to breathe with comparable pressure time product of the diaphragm. The majority of the patients showed mismatching with the ventilator, although this effect was more pronounced in the groups with chronic obstructive pulmonary disease.

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Section: Methodsmentioning

confidence: 99%

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies

Nava¹,

Bruschi²,

Fracchia³

et al. 1997

Eur Respir J

143

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“…The main disadvantage of PSV is that it only works best in patients with stable respiratory conditions (i.e. an adequate sufficient ventilatory drive and somewhat preserved respiratory mechanics [8,9]). …”

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confidence: 99%

Different modes of assisted ventilation in patients with acute respiratory failure

Chiumello¹,

Pelosi²,

Calvi³

et al. 2002

European Respiratory Journal

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The aim of the present study was to verify that the patient/ventilator interaction is similar, regardless of the mode of assisted mechanical ventilation (i.e. pressure-or volume-limited) used, if tidal volume (VT) and peak inspiratory flow (PIF) are matched. Therefore, the authors compared the effects of three different modes of assisted ventilation on the work of breathing (WOB) and gas exchange in patients with acute respiratory failure.For Protocol 1, in seven patients, the authors compared pressure support, assist pressure control and assist control (with square and decelerating wave inspiratory flow pattern) set to deliver the same VT and PIF. For Protocol 2, in another 10 patients, the authors compared pressure support and assist control with high (0.8 L?s -1 ) and low (0.6 L?s -1 ) PIFs set to deliver the same VT.In Protocol 1, there was no difference in WOB and gas exchange between the three modes of assisted ventilation tested. In Protocol 2, the decrease of PIFs during assist control significantly increased WOB.In conclusion, different modes of assisted ventilation similarly reduce work of breathing and provide adequate gas exchange at fixed tidal volume and peak inspiratory flow only. During assist control, tidal volume and peak inspiratory flow (set by the physician) are the main determinants of the patient/ventilator interaction. A primary goal of mechanical ventilation is to improve gas exchange and reduce the work of breathing (WOB) of patients with acute respiratory failure, without causing iatrogenic lung injury [1]. Assisted ventilation allows the patient to contribute to minute ventilation (V9E) and offers several advantages over controlled ventilation. It can reduce the need for sedation and paralysis, decrease the risk of barotrauma [2], improve intrapulmonary gas distribution [3], and prevent muscle atrophy [4,5]. During assisted ventilation, the WOB is dependent on both the ventilator settings and the patient9s ventilatory demand and mechanics.Pressure support ventilation (PSV) is a pressurelimited, flow-cycled mode of assisted ventilation, in which each breath is supported by a constant level of pressure at the airway (Paw), so that the tidal volume (VT) and inspiratory flow are more adaptable to the patient9s own ventilatory demand [6]. This manner of supporting the patient9s own ventilatory effort may be responsible for an improved comfort and synchrony with the ventilator, and has been shown to reduce the WOB and prevent diaphragmatic fatigue in patients with respiratory failure [7]. The main disadvantage of PSV is that it only works best in patients with stable respiratory conditions (i.e. an adequate sufficient ventilatory drive and somewhat preserved respiratory mechanics [8,9]).Assist control ventilation (ACV) is a volume-limited mode of assisted ventilation, in which the VT and the peak inspiratory flow (PIF) are set by the clinician and are not altered by the patient9s ventilatory demand. If the required VT and inspiratory flow are higher than what the ventilator suppli...

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“…Traditionally, the Coefficient of Variation (CV = standard deviation/mean) in Vt, ʃEadi and Ti over all breaths for each patient in each ventilator mode was calculated [4,9] for variation analysis. However, normality was assessed using a Kolmogorov-Smirnow test that showed that some parameters were not normally distributed.…”

Section: Variation Analysis -Robust Coefficient Of Variationmentioning

confidence: 99%

“…In PS, each ventilator-delivered cycle is initiated by a pneumatic signal (flow or pressure), detected at the upper airway as produced by the patient's inspiratory effort. The pressure delivered is set by the clinician, and the transition of the (assisted) breath into expiration occurs when the inspiratory flow decreases to a predetermined level [4].…”

Section: Introductionmentioning

confidence: 99%

NAVA enhances tidal volume and diaphragmatic electro-myographic activity matching: a Range90 analysis of supply and demand

Moorhead

Piquilloud²,

Lambermont

et al. 2012

J Clin Monit Comput

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The Nagoya Conference on System Design and Patient-Ventilator Interactions During Pressure Support Ventilation

Cited by 81 publications

References 11 publications

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies

Patient-ventilator interaction and inspiratory effort during pressure support ventilation in patients with different pathologies

Different modes of assisted ventilation in patients with acute respiratory failure

NAVA enhances tidal volume and diaphragmatic electro-myographic activity matching: a Range90 analysis of supply and demand

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