- Correspondence
- Open access
- Published:
Personalised PEEP that yields the highest lung compliance versus optimal balance between overdistension and collapse during PSV: authors’ reply to Dr Stenqvist
Critical Care volume 26, Article number: 381 (2022)
Dear Editor,
We recently published a novel method to personalize PEEP in hypoxemic patients undergoing pressure support ventilation [1]. We take the opportunity to reply to Dr. Stenqvist’s comments to further clarify the details of our approach.
The method we presented in the brief report integrates electrical impedance tomography and transpulmonary pressure (PL) monitoring to identify optimal PEEP in intubated patients on pressure support ventilation (PSV). Given the well-known side effects of deep sedation and the dramatic impact of controlled ventilation on the risk of muscular atrophy [2], switching to assisted ventilation early is often pursued in intubated patients with AHRF. During assisted ventilation, titration of ventilation settings aiming for lung protection needs to consider an elusive variable: the patient’s inspiratory effort. Inspiratory effort adds to airway driving pressure to generate transpulmonary driving pressure (ΔPL), and thus to lung stress. For a given airway driving pressure, ΔPL can vary substantially depending on patient effort. In clinical practice, PL is calculated as the difference between airway pressure and esophageal pressure and ΔPL as the difference in PL between end-inspiration and end-expiration.
Patient effort, and thus its contribution to ΔPL, can be affected by PEEP. The impact of PEEP on effort depends on factors including changes in lung compliance (balance between recruitment and overdistension) [3] and gas exchange, but it could also be affected by changes in neuro-ventilatory efficiency due to PEEP-induced modifications in the conformation of the diaphragm [4].
By integrating dynamic monitoring of ΔPL through the use of esophageal pressure, we performed a PEEP trial that accounted for the impact of PEEP on inspiratory effort in three hypoxemic patients on PSV. In all cases, the identified PEEP that balanced the percentage of alveolar collapse and overdistension corresponded to the step with the highest lung compliance, suggesting that the PEEP-induced change in lung mechanics is a main determinant of the effect of PEEP on effort.
In contrast with our approach, the method proposed by Dr. Stenqvist uses a calculation of ΔPL from lung compliance indirectly derived from measurements of end-expiratory lung volume at two PEEP levels under passive conditions. Then, a lung pressure–volume curve can be constructed to identify the PEEP associated with best lung compliance. However, measures performed during passive ventilation do not always coincide with respiratory mechanics assessed during PSV (e.g., dorsal recruitment can improve regional lung compliance). In addition, given the very small sample size that we studied, we cannot conclude that optimal EIT-ΔPL-based PEEP always corresponds with the PEEP that yields the highest lung compliance. Until more patients are studied, a more complete assessment that accounts for changes in inspiratory effort at each step should be adopted.
Availability of data and materials
Not applicable.
References
Slobod D, Leali M, Spinelli E, Grieco DL, Spadaro S, Mauri T. Integrating electrical impedance tomography and transpulmonary pressure monitoring to personalize PEEP in hypoxemic patients undergoing pressure support ventilation. Crit Care. 2022;26:314.
Schepens T, Verbrugghe W, Dams K, Corthouts B, Parizel PM, Jorens PG. The course of diaphragm atrophy in ventilated patients assessed with ultrasound: a longitudinal cohort study. Crit Care. 2015;19:422.
Dianti J, Fard S, Wong J, Chan TCY, Del Sorbo L, Fan E, Amato MBP, Granton J, Burry L, Reid WD, Zhang B, Ratano D, Keshavjee S, Slutsky AS, Brochard LJ, Ferguson ND, Goligher EC. Strategies for lung- and diaphragm-protective ventilation in acute hypoxemic respiratory failure: a physiological trial. Crit Care. 2022;26:259.
Jansen D, Jonkman AH, Vries HJ, Wennen M, Elshof J, Hoofs MA, van den Berg M, Man AME, Keijzer C, Scheffer GJ, van der Hoeven JG, Girbes A, Tuinman PR, Marcus JT, Ottenheijm CAC, Heunks L. Positive end-expiratory pressure affects geometry and function of the human diaphragm. J Appl Physiol. 1985;2021(131):1328–39.
Funding
Italian Ministry of Health, Rome, Italy.
Author information
Authors and Affiliations
Contributions
ES drafted the manuscript, all authors revised for relevant intellectual content and approved the present final form.
Corresponding author
Ethics declarations
Ethical approval
Not applicable.
Competing interests
TM reports receiving speaker’s fees from Drager, Fisher and Paykel, Mindray, Hamilton, outside of the submitted work. The other authors have nothing to disclose.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
About this article
Cite this article
Spinelli, E., Slobod, D. & Mauri, T. Personalised PEEP that yields the highest lung compliance versus optimal balance between overdistension and collapse during PSV: authors’ reply to Dr Stenqvist. Crit Care 26, 381 (2022). https://doi.org/10.1186/s13054-022-04261-0
Received:
Accepted:
Published:
DOI: https://doi.org/10.1186/s13054-022-04261-0