Maneuver-Free Determination of Compliance and Resistance in Ventilated ARDS Patients

Guttmann, J.; Eberhard, L.; Wolff, G.; Bertschmann, W; Zeravik, J.; Adolph, M.

doi:10.1378/chest.102.4.1235

Cited by 35 publications

(29 citation statements)

References 10 publications

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“…This could be explained with a parallel slow compartment [26,27] and/ or with viscoelasticity. In common with other authors, we have observed time-consuming pressure equilibration processes in ARDS patients during an end-inspiratory pause [28,29], as well as during an end-expiratory occlusion manoeuvre [21,30,31]. Because in our continuously ventilated patients expiratory time could only be increased by reducing inspiratory time and avoiding an end-inspiratory pause, the viscoelastic compartment becomes "occult" [32].…”

Section: Discussionsupporting

confidence: 81%

Time constant/volume relationship of passive expiration in mechanically ventilated ARDS patients

Guttmann¹,

Eberhard²,

Fabry³

et al. 1995

Eur Respir J

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T Ti im me e c co on ns st ta an nt t/ /v vo ol lu um me e r re el la at ti io on ns sh hi ip p o of f p pa as ss si iv ve e e ex xp pi ir ra at ti io on n i in n m me ec ch ha an ni ic ca al ll ly y v ve en nt ti il la at te ed d A AR RD DS S p pa at ti ie en nt ts s The mean values of τE for each volume slice did not differ significantly throughout expiration, averaging 690±218 ms (mean±SD of five slices and 12 patients). We show that the flow-dependent resistance of the endotracheal tube (RETT) is mainly responsible for the observed time constant homogeneity.We conclude that in ARDS patients during uninterrupted mechanical ventilation the time constants of passive expiration are markedly modified by the flow-dependent resistance of the endotracheal tube (RETT), and also by the external resistance of tubing and ventilator (REX). RETT and REX render τE about three times larger than the time constant of the patient's respiratory system alone.

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Section: Discussionsupporting

confidence: 81%

Time constant/volume relationship of passive expiration in mechanically ventilated ARDS patients

Guttmann¹,

Eberhard²,

Fabry³

et al. 1995

Eur Respir J

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“…In our series the application of incremental levels of PEEP did not counterbalance the increase in Rdyn. The flow and volume data reported are considered to apply purely to the animals' respiratory mechanics, excluding the effects of additional resistance due to the ETT [7]. The accuracy of Ptrach corrections for the ETT during PLV have, however, not been systematically evaluated and PFC mucus formation might have significantly affected the accuracy of Ptrach corrections for the ETT.…”

Section: Discussionmentioning

confidence: 99%

“…Respiratory mechanics were determined using a leastsquare fitting method for selected parts of the PV loop according to the method of GUTTMANN, described in detail elsewhere [7]. Since the ETT imposes a significant additional resistance on the respiratory system, the pressure drop across the ETT (PETT) was also calculated according to the method described by GUTTMANN [8].…”

Section: Flow and Volume Datamentioning

confidence: 99%

Superimposing positive end-expiratory pressure during partial liquid ventilation in experimental lung injury

Kaisers

Kuhlen²,

Keske³

et al. 1998

Eur Respir J

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This study was undertaken to determine the effects of superimposing incremental levels of positive end-expiratory pressure (PEEP) during partial liquid ventilation (PLV) on gas exchange, respiratory mechanics and morphological changes in experimental acute lung injury (ALI). In a prospective trial, six pigs weighing 30+/-5 kg (mean+/-SD) were tracheotomized, submitted to pressure-controlled mechanical ventilation (pc-CMV) and depleted of surfactant by lung lavage. Animals were then mechanically ventilated with three levels of PEEP: 0.5, 1.0 and 1.5 kPa. PLV was then initiated by intratracheal instillation of 30 mL x kg(-1) perfluorocarbon, followed by pc-CMV with PEEP 0.5, 1.0 and 1.5 kPa. Computed tomography (CT)-based analyses of lung volumes and density were obtained after lung lavage, in PLV and during the combined application of PLV and PEEP. Simultaneously, haemodynamics, gas exchange, dynamic compliance (Cdyn) and dynamic resistance (Rdyn) were determined. Statistical analysis was performed using multivariate analyses of variance for repeated measures (p<0.05). In ALI and before PLV, the application of PEEP significantly reduced cardiac output and intrapulmonary shunt. Arterial oxygen tension (Pa,O2) was increased from 6.9 kPa (52 (42, 54) mmHg) (median, (25th and 75th percentile)) to 8.6 kPa (65 (52, 133) mmHg) (PEEP 1.0 kPa) and 15.6 kPa (117 (90, 195) mmHg) (PEEP 15 kPa) (p<0.05). The lung volume obtained by CT increased, CT density was reduced (p<0.05), Cdyn tended to increase and Rdyn to decrease (nonsignificant). PLV increased arterial carbon dioxide tension and reduced pH (p<0.05). CT lung volume and lung density were increased (p<0.05). Superimposing PEEP on PLV increased Pa,O2 from 9.3 kPa (70 (52,124) mmHg) (PEEP 0.5 kPa) to 12.9 kPa (97 (55, 233) mmHg) (PEEP 1.0 kPa) and 403 kPa (303 (64, 426) mmHg) (PEEP 1.5 kPa) (p<0.05), but had no significant effect on CT lung volume and density. It was concluded that in experimental lung injury, positive end-expiratory pressure provided alveolar recruitment. The combined application of positive end-expiratory pressure and partial liquid ventilation significantly augmented oxygenation and might eventually allow either a reduction in the volumes of perfluorocarbons required, or a reduction in positive end-expiratory pressure necessary to maintain pulmonary gas exchange in acute lung injury.

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“…In the absence of a gold standard one must accept the conditions imposed by the methodology. Calculating resistance and compliance by multiple linear regression performed on the whole inspiratory and/or expiratory limbs of the proximal P/V loop [25,28] is based on the assumption of constant resistance and compliance throughout the tidal volume or inspiratory and expiratory limb. When multiple linear regression is applied on a P/V loop divided into slices [27,29], the resistance and compliance is assumed to be constant within each slice.…”

Section: Methodological Considerationsmentioning

confidence: 99%

Alveolar pressure monitoring: an evaluation in a lung model and in patients with acute lung injury

et al. 2003

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Maneuver-Free Determination of Compliance and Resistance in Ventilated ARDS Patients

Cited by 35 publications

References 10 publications

Time constant/volume relationship of passive expiration in mechanically ventilated ARDS patients

Time constant/volume relationship of passive expiration in mechanically ventilated ARDS patients

Superimposing positive end-expiratory pressure during partial liquid ventilation in experimental lung injury

Alveolar pressure monitoring: an evaluation in a lung model and in patients with acute lung injury

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