Avoid common mistakes on your manuscript.
Dear Editor,
To date, lung computed tomography (CT) scan is the gold standard to assess the distribution of acute respiratory distress syndrome (ARDS) patient’s lung strain [1]. Since CT-based methods are impractical and cannot be used to monitor ARDS lung characteristics throughout prone ventilation, methods feasible at the bedside are very attractive and lung ultrasound (LUS) is one of them. We aimed to compare for the first time, LUS to the end-expiratory lung volume (EELV, measured by automated nitrogen washout/washin technique) [2] for assessing prone positioning-induced lung inflation.
At variance with previous reports [3] and because at best we can only expect LUS techniques to quantitate the degree of “inflation” induced by lung recruitment, we have decided to compare LUS to a lung inflation reference method (EELV), rather than using arterial gas exchange (which depends on both lung ventilation and perfusion) as the main study endpoint. A threshold of EELV of 500 ml was used to define a binarized prone positioning response (responders vs not responders) [2]. Ultrasound examinations were performed and analyzed only by physicians with advanced LUS experience and previously reported interobserver agreement [4, 5]. Forty-five patients with moderate-to-severe ARDS (PaO2/FiO2 < 150 with FiO2 at least 0.6 and positive end-expiratory (PEEP) at least 5 mmHg) were prospectively included. LUS data, arterial blood gas analysis, and ventilator variables were systematically recorded immediately before prone positioning (PP), 1 h (early) and 16 h (late) after PP onset. Lung hyperinflation was not specifically assessed. Thereby, we have observed in this proof-of-concept study that:
-
LUS score variations throughout PP session (Fig. 1, upper panel), but not basal LUS data in a supine position, are significantly associated with PP response both in terms of lung inflation and blood oxygen level improvement.
-
PP-induced lung inflation greater than 500 ml can accurately be estimated by a LUS reaeration score [3] of 10 or greater (Fig. 1, upper panel).
-
LUS appears to be a reliable bedside tool to evaluate regional PP-induced gain or loss of lung aeration (Fig. 1, lower panel). Moreover, ultrasound analysis of pulmonary aeration changes at both early and late PP assessments, showed that a significant response to PP was related to a reduced number of pattern’s transitions: B2 (multiple coalescent B lines) to normal, C (lung consolidation) to normal and C to B1 (multiple well-defined either regularly spaced 7-mm apart or irregularly spaced B lines). It is worth noting, that at the late-PP time point a significant increase of B-lines profiles was also observed in previously normally aerated lung regions.
-
Repeated LUS assessment across the time, accurately allow lung inflation monitoring during PP sessions (Fig. 1, upper and lower panels). However, neither LUS nor EELV can detect lung hyperinflation and as a consequence, should not be used in isolation as methods of respiratory monitoring in ARDS.
We believe that our data make a significant contribution to advancing the understanding and care of ARDS. We suggest that these findings have clinical implications and might be particularly relevant for further personalize the use of PP in this challenging clinical setting.
References
Thompson BT, Chambers RC, Liu KD (2017) Acute respiratory distress syndrome. N Engl J Med 377:562–572
Dellamonica J, Lerolle N, Sargentini C, Beduneau G, Di Marco F, Mercat A, Richard JC, Diehl JL, Mancebo J, Rouby JJ, Lu Q, Bernardin G, Brochard L (2011) Accuracy and precision of end-expiratory lung-volume measurements by automated nitrogen washout/washin technique in patients with acute respiratory distress syndrome. Crit Care 15:R294
Haddam M, Zieleskiewicz L, Perbet S, Baldovini A, Guervilly C, Arbelot C, Noel A, Vigne C, Hammad E, Antonini F, Lehingue S, Peytel E, Lu Q, Bouhemad B, Golmard JL, Langeron O, Martin C, Muller L, Rouby JJ, Constantin JM, Papazian L, Leone M, Network CAEC, AzuRea Collaborative N (2016) Lung ultrasonography for assessment of oxygenation response to prone position ventilation in ARDS. Intensive Care Med 42:1546–1556
Silva S, Ait Aissa D, Cocquet P, Hoarau L, Ruiz J, Ferre F, Rousset D, Mora M, Mari A, Fourcade O, Riu B, Jaber S, Bataille B (2017) Combined thoracic ultrasound assessment during a successful weaning trial predicts postextubation distress. Anesthesiology 127:666–674
Silva S, Biendel C, Ruiz J, Olivier M, Bataille B, Geeraerts T, Mari A, Riu B, Fourcade O, Genestal M (2013) Usefulness of cardiothoracic chest ultrasound in the management of acute respiratory failure in critical care practice. Chest 144:859–865
Acknowledgements
Members of the PLUS study group (Monitoring Prone positioning lung inflation by Lung UltraSound): Amazigh Aguersif, Sihem Bouharoua, Hélène Vinour, Edith Hourcastagnou, Guillaume Ducos, Muriel Picard, Veronique Ramonda, Jean Ruiz.
Author information
Authors and Affiliations
Consortia
Corresponding author
Ethics declarations
Conflicts of interest
The authors declare that they have no conflict of interest.
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-NonCommercial 4.0 International License, which permits any non-commercial 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-nc/4.0/.
About this article
Cite this article
Rousset, D., Sarton, B., Riu, B. et al. Bedside ultrasound monitoring of prone position induced lung inflation. Intensive Care Med 47, 626–628 (2021). https://doi.org/10.1007/s00134-021-06347-9
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00134-021-06347-9