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

Spieth, Peter M.; Güldner, Andreas; Uhlig, Christopher; Bluth, Thomas; Kiss, Thomas; Conrad, Carol; Bischlager, K.; Braune, Anja; Huhle, Robert; Insorsi, Angelo; Tarantino, Fabio; Ball, Lorenzo; Schultz, Marcus J.; Abolmaali, Nasreddin; Koch, Thea; Pelosi, Paolo; Abreu, Marcelo Gama de

doi:10.1016/j.bja.2017.11.078

Cited by 19 publications

(15 citation statements)

References 42 publications

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“…The most likely mechanism by which VV improves lung mechanics is recruitment 23 and enhanced surfactant secretion 31,32 . To our knowledge, only one study applied VV in human subjects during abdominal surgery which did not result in any physiological improvement 56 ; however, the subjects had normal lungs and the results are similar to our mouse data before lavage. Another possibility is that the ventilation time and/or settings were suboptimal for improvements to occur.…”

Section: Human Clinical Trial Fromsupporting

confidence: 82%

Tracking respiratory mechanics around natural breathing rates via variable ventilation

Jawde

Walkey

Majumdar

et al. 2020

Sci Rep

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Measuring respiratory resistance and elastance as a function of time, tidal volume, respiratory rate, and positive end-expiratory pressure can guide mechanical ventilation. However, current measurement techniques are limited since they are assessed intermittently at non-physiological frequencies or involve specialized equipment. to this end, we introduce ZVV, a practical approach to continuously track resistance and elastance during Variable Ventilation (VV), in which frequency and tidal volume vary from breath-to-breath. ZVV segments airway pressure and flow recordings into individual breaths, calculates resistance and elastance for each breath, bins them according to frequency or tidal volume and plots the results against bin means. ZVV's feasibility was assessed clinically in five human patients with acute lung injury, experimentally in five mice ventilated before and after lavage injury, and computationally using a viscoelastic respiratory model. ZVV provided continuous measurements in both settings, while the computational study revealed <2% estimation errors. Our findings support ZVV as a feasible technique to assess respiratory mechanics under physiological conditions. Additionally, in humans, ZVV detected a decrease in resistance and elastance with time by 12.8% and 6.2%, respectively, suggesting that VV can improve lung recruitment in some patients and can therefore potentially serve both as a dual diagnostic and therapeutic tool.Respiratory resistance (R) and elastance (E) in mechanically ventilated patients relate to disease severity and progression, and patient response to treatment or changes in ventilator settings 1-3 . The manner in which R and E vary with frequency can reflect lung heterogeneity, a sensitive indicator of pathology 4 . Thus, a technique that can continuously and reliably assess R and E at physiological frequencies and tidal volumes (V T 's) could advance the treatment of mechanically ventilated patients. For example, increases in R can reveal bronchospasm 5 or a blocked endotracheal tube 6,7 , while increases in E can reflect pulmonary edema and alveolar derecruitment 8,9 . Tracking continuously R and E including their frequency dependencies could improve patient management via detection of airway obstruction in asthma, or optimization of mechanical ventilator settings for preventing ventilation-induced lung injury 10-15 .Nevertheless, estimates of R and E are rarely performed in clinical practice 16 , likely due to current strategies of intermittent end inspiratory occlusion measurements that require deep patient sedation or paralysis or the need for specialized equipment 10,17 . In order to adjust ventilation settings, clinicians are currently guided by gas exchange parameters, breath-to-breath peak pressures, and plateau pressures 16,[18][19][20] . However, these measures lack the ability to reveal whether abnormalities in mechanics are related to altered R or E and often require a heavily sedated or paralyzed patient 9,21 . The limitations in measuring R and E are not only pres...

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Section: Human Clinical Trial Fromsupporting

confidence: 82%

Tracking respiratory mechanics around natural breathing rates via variable ventilation

Jawde

Walkey

Majumdar

et al. 2020

Sci Rep

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“…Of note, a recent clinical trial found no improvement in postoperative respiratory function with controlled variable ventilation compared with non-variable ventilation during general anaesthesia for abdominal surgery. 44 These findings suggest that physiological variable ventilation extrapolated from the spontaneous breathing pattern provides optimal gas exchange with minimal deleterious effects on the lung. Hence, these results may stimulate further investigations towards a more personalised protective mechanical ventilation.…”

Section: Discussionmentioning

confidence: 85%

Comparison between neurally-assisted, controlled, and physiologically variable ventilation in healthy rabbits

Walesa

Bayat

Albu

et al. 2018

British Journal of Anaesthesia

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“…The acquisition variables were set as follows: echo time 1.88 ms, repetition time 4.08 ms, field of view 300 × 300 mm 2 , 1.2 × 1.2 mm 2 in-plane resolution, flip angle 4°, 580 radial views and 176–224 1.3 mm thick slices depending on the size of the lungs. Acquisition times ranged from 225 to 287 s. The choice of a StarVIBE sequence over the more usual VIBE one (Spieth et al, 2018) was motivated by its isotropic voxel resolution allowing accurate 3D segmentation and its relative robustness to motion artifacts. A T2-weighted breath-hold TrueFISP sequence was also acquired with the following parameters: TE/TR = 1.43 ms/391 ms, in-plane resolution 0.8 × 0.8 mm 2 , 70 4-mm thick slices, acquisition time 27 s. This sequence was chosen for its short acquisition time.…”

Section: Methodsmentioning

confidence: 99%

Validation of MRI for Volumetric Quantification of Atelectasis in the Perioperative Period: An Experimental Study in Swine

et al. 2019

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Background: Impairment of pulmonary aeration is a frequent postoperative complication that is associated with adverse outcome. Diagnosis and quantification of impaired pulmonary aeration by CT scan is limited due to concern for exposure to ionizing radiation. Magnetic resonance imaging (MRI) represents a potential radiation-free alternative for this use. We undertook an experimental study to validate the use of MRI to quantify pulmonary aeration impairment. Methods: Ten large white pigs were studied before intubation, after intubation, 2 h after non-protective mechanical ventilation and after intra-tracheal negative pressure suction to induce atelectasis. A lung CT scan immediately followed by a lung MRI were performed at all four time points. On the 40 CT images lung volumes corresponding to non-aerated, poorly aerated, normally aerated, and overinflated voxels were measured based on their radiodensity. Similarly, on the 40 MRI images lung volumes corresponding to non-aerated and aerated voxels were measured based on their signal intensity. The correlation between non-aerated lung by MRI vs., CT scans, and with PaO 2 /FiO 2 measured at each of the four time points was assessed with the Pearson’ correlation coefficient, bias and limits of agreement. Results: Pearson correlation coefficient, bias and limits of agreements between the CT non-aerated lung volumes and MRI abnormal lung volumes were 0.88, -16 ml, and (-108, 77), respectively. Pearson correlation coefficient between PaO 2 /FiO 2 and abnormal lung volumes measured with MRI was -0.60. Conclusion: In a preclinical swine model, quantitative measurements of pulmonary atelectasis by MRI-imaging are well correlated with the gold standard, i.e., densitometric scan CT measurements.

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

Abstract: NCT 01683578.

Cited by 19 publications

References 42 publications

Tracking respiratory mechanics around natural breathing rates via variable ventilation

Tracking respiratory mechanics around natural breathing rates via variable ventilation

Comparison between neurally-assisted, controlled, and physiologically variable ventilation in healthy rabbits

Validation of MRI for Volumetric Quantification of Atelectasis in the Perioperative Period: An Experimental Study in Swine

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