Effects of extrinsic positive end-expiratory pressure on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

Georgopoulos, Dimitris; Giannouli, Eleni; Patakas, D.

doi:10.1007/bf01694770

Cited by 56 publications

(39 citation statements)

References 26 publications

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“…The two V9/V curves were superimposed assuming that the end-inspiratory lung level was identical under both conditions, as indicated by a similar Ptr at the end of inspiratory occlusion. The presence of flow limitation was assessed by comparing expiratory V9 over a given portion of lung V [8,10,14]. If expiratory V9 was consistently higher when downstream P was lowered by removing the expiratory ventilator circuit or decreasing the PEEP level, the V portion was classified as being without flow limitation ( fig.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, it has been shown that mechanically-ventilated patients with ARDS may exhibit flow limitation during tidal expiration [8]. In which case the endotracheal tube resistance (Rtube), as well as the expiratory ventilator circuit, may not affect the expiratory flow and, thus, the rate of lung emptying [9,10]. It follows that calculating the ters without knowing if expiratory flow at the volume of interest is or is not limited might be misleading.…”

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confidence: 99%

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Lung emptying in patients with acute respiratory distress syndrome: effects of positive end-expiratory pressure

Kondili¹,

Prinianakis²,

Athanasakis³

et al. 2002

Eur Respir J

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The pattern of lung emptying was studied in 10 mechanically-ventilated patients with acute respiratory distress syndrome.At four levels of positive end-expiratory pressure (PEEP) (0, 5, 10 and 15 cmH 2 O) tracheal (Ptr) and airway pressures (Paw), flow (V9) and volume (V) were continuously recorded. Tidal volume was set between 0.5-0.6 L and V9/V curves during passive expiration were obtained. Expired volume was divided into five equal volume slices and the time constant (te) and effective deflation compliance (Crs eff ) of each slice was calculated by regression analysis of V/V9 and postocclusion V/Ptr relationships, respectively. In each slice, the presence or absence of flow limitation was examined by comparing V9/V curves with and without decreasing Paw. For a given slice, total expiratory resistance (Rtot) (consisting of the respiratory system (Rrs), endotracheal tube (Rtube) and ventilator circuit (Rvent)) was calculated as the te/Crs eff ratio. In the absence of flow limitation Rrs was obtained by subtracting Rtube and Rvent from Rtot, while in the presence of flow limitation Rrs equaled Rtot. The te of the pure respiratory system (ters) was calculated as the product of Rrs and Crs eff .At zero PEEP, ters increased significantly towards the end of expiration (52¡31%) due to a significant increase in Rrs (46¡36%). Application of PEEP significantly decreased Rrs at the end of expiration and resulted in a faster and relatively constant rate of lung emptying.In conclusion, without positive end-expiratory pressure the respiratory system in patients with acute respiratory distress syndrome deflates with a rate that progressively decreases, due to a considerable increase in expiratory resistance at low lung volumes. Application of positive end-expiratory pressure decreases the expiratory resistance, probably by preventing airway closure, and as a result modifies the pattern of lung emptying.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Lung emptying in patients with acute respiratory distress syndrome: effects of positive end-expiratory pressure

Kondili¹,

Prinianakis²,

Athanasakis³

et al. 2002

Eur Respir J

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“…Hence, inspiration begins at volumes at which the respiratory system exhibits a positive recoil pressure, referred to as intrinsic PEEP (PEEPi) [18][19][20][21][22]. This phenomenon is called dynamic hyperinflation and is a common finding in mechanically-ventilated patients [18][19][20][21].…”

Section: Missing Effortmentioning

confidence: 99%

Control of breathing in mechanically ventilated patients

Georgopoulos¹,

Roussos²

1996

Eur Respir J

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Thus, the response of ventilator to patient effort, and that of patient effort to ventilator-delivered breath are inevitably the two components of control of breathing during mechanical ventilation; the ventilatory output is the final expression of the interaction between these two components. As a result of this interaction, the various aspects of control of breathing of the respiratory system may be masked or modulated by mechanical ventilation, depending on several factors related both to patient and ventilator. This should be taken into consideration in the management of mechanically ventilated patients.

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“…In mechanically ventilated patients with chronic obstructive pulmonary disease (COPD), the effect of PEEP on DRrs has also been studied. In one study, by experimental design, the maximal applied PEEP was limited to 86% of the intrinsic PEEP [6]. Under the latter conditions, the changes in end-expiratory lung volume (EELV) were necessarily very small (mean of 0.13 L), and accordingly in that study, there was little or no change of DRrs and Rint,rs.…”

mentioning

confidence: 98%

Effects of PEEP on inspiratory resistance in mechanically ventilated COPD patients

2001

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This study aimed to investigate the effect of increased lung volume with positive end-expiratory pressure (PEEP) on respiratory resistance in patients with chronic obstructive pulmonary disease (COPD).Ten patients with COPD were mechanically ventilated for acute respiratory failure. PEEP was set at 0, 5, 10 and 15 cmH 2 O. Using the rapid airway occlusion technique, the total inspiratory resistance of the respiratory system was partitioned into interrupter (Rint,rs) and additional effective (DRrs) resistances. At each level of PEEP, at constant inflation flow, the inflation volume (DV) was varied from 0.2-1 L, and, at constant DV, the inflation flow was varied from 0.2-1.2 L?s -1 . The changes in end-expiratory lung volume (DEELV) induced by PEEP were also measured.The difference between the EELV and the relaxation volume of the respiratory system (DFRC) increased significantly with PEEP of 10 and 15 cmH 2 O as compared to a PEEP of 0, the increase being associated with a significant reduction of Rint,rs. By contrast, DRrs was independent of DFRC. At constant DV, Rint,rs fitted Rohrer9s equation (Rint,rs =K1zK26flow). While K 2 significantly declined with DFRC, K 1 did not change. At all levels of PEEP, DRrs was not influenced by DFRC.With increasing lung volume induced by positive end-expiratory pressure, the inspiratory airway resistance decreased, whereas the viscoelastic behaviour of the respiratory system, as reflected by additional effective resistance, did not change.

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Effects of extrinsic positive end-expiratory pressure on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

Abstract: The effects of PEEPe on iso-volume flow and hence on lung mechanics and hemodynamics, depend on many factors, such as airways resistances, lung volumes and airway characteristics, making the patient response to PEEPe unpredictable.

Cited by 56 publications

References 26 publications

Lung emptying in patients with acute respiratory distress syndrome: effects of positive end-expiratory pressure

Lung emptying in patients with acute respiratory distress syndrome: effects of positive end-expiratory pressure

Control of breathing in mechanically ventilated patients

Effects of PEEP on inspiratory resistance in mechanically ventilated COPD patients

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