Variable ventilation from bench to bedside

Huhle, Robert; Pelosi, Paolo; Abreu, Marcelo Gama de

doi:10.1186/s13054-016-1216-6

Cited by 26 publications

(25 citation statements)

References 50 publications

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“…33 The lack of improvement in E rs during CVV evidences that the volumepressure relationship of the respiratory system was rather linear, precluding substantial lung recruitment. 28 In view of these facts, we hypothesize that intraoperative atelectasis was relatively low in our patients, which is partially supported by Values are given as mean (SD). Pulmonary function tests refer to expected normal values of patients (%).…”

Section: Discussionsupporting

confidence: 66%

“…We tested CVV, because experimental evidence showed it is effective in recruiting lungs and leads to less impairment of haemodynamics than traditional recruitment manoeuvres. 28 Furthermore, variable V T has been shown to improve lung-protective ventilation strategies in experimental models of acute lung injury. 13,29 To assess the isolated effects of CVV, we maintained mean V T and PEEP comparable between groups.…”

Section: Discussionmentioning

confidence: 99%

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Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Spieth

Güldner

Uhlig

et al. 2018

British Journal of Anaesthesia

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Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Spieth

Güldner

Uhlig

et al. 2018

British Journal of Anaesthesia

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“…It is well known that high tidal volumes during mechanical ventilation can initiate or worsen lung injury, a phenomenon known as ventilator-induced lung injury (VILI) [ 22 ]. Therefore, protective strategies based upon low distending pressures (driving pressure) and tidal volumes have been developed to reduce the stress of mechanical ventilation to the lung parenchyma [ 23 ]. In experimental ARDS, variable tidal volumes have been shown to improve respiratory lung function, and further reduce histological damage [ 2 ] as well as decrease cytokine release [ 1 ] compared to conventional (non-variable) protective low tidal volumes.…”

Section: Discussionmentioning

confidence: 99%

Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells

et al. 2017

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Mechanical ventilation has the potential to increase inflammation in both healthy and injured lungs. Several animal studies have shown that variable ventilation recruits the lungs and reduces inflammation. However, it is unclear which cellular mechanisms are involved in those findings. We hypothesized that variable stretch of LPS-stimulated alveolar epithelial cells (AECs) reduces the production of pro-inflammatory cytokines compared to non-variable stretch. AECs were subjected to non-variable or variable cyclic stretch (sinusoidal pattern), with and without LPS stimulation. The expression and release of interleukin-6, CXCL-2 and CCL-2 mRNA were analyzed after 4 hours. The phosphorylation of the MAPKs ERK1/ 2 and SAPK/JNK was determined by Western Blot analysis at 0, 15, 30, 45 and 60 min of cyclic stretch. In LPS-stimulated AECs, variable cyclic cell stretching led to reduced cytokine expression and release compared to non-variable cell stretching. Furthermore, the phosphorylation of the MAPK ERK1/2 was increased after 30 minutes in non-variable stretched AECs, whereas variable stretched cells demonstrated only the non-stretched level of phosphorylation. After the 4h period of cyclic cell stretch and inhibition of the ERK1/2, but not the SAPK/JNK, signaling pathway, the gene expression of investigated cytokines increased in variable stretched, and decreased in non-variable stretched AECs. We conclude that in LPS-stimulated AECs, variable stretch reduced the pro-inflammatory response compared to non-variable stretch. This effect was mediated by the ERK1/2 signaling pathway, and might partly explain the findings of reduced lung inflammation during mechanical ventilation modes that enhance breath-by-breath variability of the respiratory pattern.

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“…The EELV ranged from 1.0 to 4.244 L [ 11 , 12 ] with N = 50 alveolar units log-distributed on in the range of 0.01–100. Mean V T was 0.5 L [ 13 ] and was kept constant or with a variability of 25 % [ 14 ]. The was of 0.125 L [ 15 ].…”

Section: Methodsmentioning

confidence: 99%

Generalized estimation of the ventilatory distribution from the multiple-breath nitrogen washout

Ribeiro

Jandre

Wrigge³

et al. 2016

BioMed Eng OnLine

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BackgroundThis work presents a generalized technique to estimate pulmonary ventilation-to-volume (v/V) distributions using the multiple-breath nitrogen washout, in which both tidal volume (VT) and the end-expiratory lung volume (EELV) are allowed to vary during the maneuver. In addition, the volume of the series dead space (vd), unlike the classical model, is considered a common series unit connected to a set of parallel alveolar units.MethodsThe numerical solution for simulated data, either error-free or with the N2 measurement contaminated with the addition of Gaussian random noise of 3 or 5 % standard deviation was tested under several conditions in a computational model constituted by 50 alveolar units with unimodal and bimodal distributions of v/V. Non-negative least squares regression with Tikhonov regularization was employed for parameter retrieval. The solution was obtained with either unconstrained or constrained (VT, EELV and vd) conditions. The Tikhonov gain was fixed or estimated and a weighting matrix (WM) was considered. The quality of estimation was evaluated by the sum of the squared errors (SSE) (between reference and recovered distributions) and by the deviations of the first three moments calculated for both distributions. Additionally, a shape classification method was tested to identify the solution as unimodal or bimodal, by counting the number of shape agreements after 1000 repetitions.ResultsThe accuracy of the results showed a high dependence on the noise amplitude. The best algorithm for SSE and moments included the constrained and the WM solvers, whereas shape agreement improved without WM, resulting in 97.2 % for unimodal and 90.0 % for bimodal distributions in the highest noise condition.ConclusionsIn conclusion this generalized method was able to identify v/V distributions from a lung model with a common series dead space even with variable VT. Although limitations remain in presence of experimental noise, appropriate combination of processing steps were also found to reduce estimation errors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12938-016-0213-y) contains supplementary material, which is available to authorized users.

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Variable ventilation from bench to bedside

Cited by 26 publications

References 50 publications

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Variable stretch reduces the pro-inflammatory response of alveolar epithelial cells

Generalized estimation of the ventilatory distribution from the multiple-breath nitrogen washout

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