Davide Chiumello Massimo Cressoni Andrea Colombo Giovanni Babini Matteo Brioni Francesco Crimella Stefan Lundin Ola Stenqvist Luciano Gattinoni The assessment of transpulmonary pressure in mechanically ventilated ARDS patients Received: 1 May 2014 Accepted: 19 July 2014 Ó Springer-Verlag Berlin Heidelberg and ESICM 2014 Take-home message: The end-inspiratory transpulmonary pressure can be accurately computed by the elastance-derived method which, compared to the release method, avoids the risk of ventilator disconnection, while the directly measured end-expiratory transpulmonary pressure is not related to the release-derived transpulmonary pressure. Electronic supplementary material The online version of this article (doi:10.1007/s00134-014-3415-4) contains supplementary material, which is available to authorized users. D. Chiumello ( ) ) Á L. Gattinoni Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda– Ospedale Maggiore Policlinico, Via F. Sforza 35, Milan, Italy e-mail: chiumello@libero.it Tel.: ?39-2-55033237 D. Chiumello Á M. Cressoni Á A. Colombo Á G. Babini Á M. Brioni Á F. Crimella Á L. Gattinoni Dipartimento di Fisiopatologia Medico- Chirurgica e dei Trapianti, Universita ` degli Studi di Milano, Milan, Italy S. Lundin Á O. Stenqvist Department of Anesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden Abstract Purpose: The optimal method for estimating transpulmo- nary pressure (i.e. the fraction of the airway pressure transmitted to the lung) has not yet been established. Methods: In this study on 44 patients with acute respiratory dis- tress syndrome (ARDS), we computed the end-inspiratory trans- pulmonary pressure as the change in airway and esophageal pressure from end-inspiration to atmospheric pres- sure (i.e. release derived) and as the product of the end-inspiratory airway pressure and the ratio of lung to respiratory system elastance (i.e. elastance derived). The end-expira- tory transpulmonary pressure was estimated as the product of positive end-expiratory pressure (PEEP) minus the direct measurement of esophageal pressure and by the release method. Results: The mean elastance- and release-derived trans- pulmonary pressure were 14.4 ± 3.7 and 14.4 ± 3.8 cmH 2 O at 5 cmH 2 O of PEEP and 21.8 ± 5.1 and 21.8 ± 4.9 cmH 2 O at 15 cmH 2 O of PEEP, respectively (P = 0.32, P = 0.98, respectively), indicating that these parameters were signifi- cantly related (r 2 = 0.98, P \ 0.001 at 5 cmH 2 O of PEEP; r 2 = 0.93, P \ 0.001 at 15 cmH 2 O of PEEP). The percentage error was 5.6 and 12.0 %, respectively. The mean directly mea- sured and release-derived transpulmonary pressure were -8.0 ± 3.8 and 3.9 ± 0.9 cmH 2 O at 5 cmH 2 O of PEEP and -1.2 ± 3.2 and 10.6 ± 2.2 cmH 2 O at 15 cmH 2 O of PEEP, respectively, indicating that these parameters were not related (r 2 = 0.07, P = 0.08 at 5 cmH 2 O of PEEP; r 2 = 0.10, P = 0.53 at 15 cmH 2 O of PEEP). Conclu- sions: Based on our observations, elastance-derived transpulmonary pressure can be considered to be an adequate surrogate of the release- derived transpulmonary pressure, while the release-derived and directly measured end-expiratory transpulmo- nary pressure are not related. Keywords Acute respiratory distress syndrome Á Computed tomography Á Transpulmonary pressure Á Esophageal pressure Á PEEP Intensive Care Med DOI 10.1007/s00134-014-3415-4 ORIGINAL