Difference in pulmonary permeability between indirect and direct acute respiratory distress syndrome assessed by the transpulmonary thermodilution technique: a prospective, observational, multi-institutional study.

Kenichiro Morisawa,Ryutarou Seo,Takashi Kanemura,Toshiaki Nakamura,Takayuki Irahara,Yasuhiko Taira,Manabu Sugita,Junko Yamaguchi,Teruo Sakamoto,Makoto Takatori,Tadashi Kaneko,Shigeki Fujitani,Hiroyuki Takahashi,Akihiro Watanabe,Nobuyuki Saitou,Hiroshi Rinka,Kazuo Okuchi,Hiroyasu Ishikura,Shigeki Kushimoto,Hiroo Izumino,Takashi Tagami,Yoshiaki Kitazawa ,Y Kuroki ,Yasuhiro Kase

doi:10.1186/2052-0492-2-24

Abstract

BackgroundAcute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins. Especially, the distinction between a direct (pulmonary injury) and an indirect (extrapulmonary injury) lung injury etiology is gaining more attention as a means of better comprehending the pathophysiology of ARDS. However, there are few reports regarding the quantitative methods distinguishing the degree of pulmonary permeability between ARDS patients due to pulmonary injury and extrapulmonary injury.MethodsA prospective, observational, multi-institutional study was performed in 23 intensive care units of academic tertiary referral hospitals throughout Japan. During a 2-year period, all consecutive ARDS-diagnosed adult patients requiring mechanical ventilation were collected in which three experts retrospectively determined the pathophysiological mechanisms leading to ARDS. Patients were classified into two groups: patients with ARDS triggered by extrapulmonary injury (ARDSexp) and those caused by pulmonary injury (ARDSp). The degree of pulmonary permeability using the transpulmonary thermodilution technique was obtained during the first three intensive care unit (ICU) days.ResultsIn total, 173 patients were assessed including 56 ARDSexp patients and 117 ARDSp patients. Although the Sequential Organ Failure Assessment (SOFA) score was significantly higher in the ARDSexp group than in the ARDSp group, measurements of the pulmonary vascular permeability index (PVPI) were significantly elevated in the ARDSp group on all days: at day 0 (2.9 ± 1.3 of ARDSexp vs. 3.3 ± 1.3 of ARDSp, p = .008), at day 1 (2.8 ± 1.5 of ARDSexp vs. 3.2 ± 1.2 of ARDSp, p = .01), at day 2 (2.4 ± 1.0 of ARDSexp vs. 2.9 ± 1.3 of ARDSp, p = .01). There were no significant differences in mortality at 28 days, mechanical ventilation days, and hospital length of stay between the two groups.ConclusionsThe results of this study suggest the existence of several differences in the increased degree of pulmonary permeability between patients with ARDSexp and ARDSp.Trial registrationThis report is a sub-group analysis of the study registered with UMIN-CTR (IDUMIN000003627).

Highlights

Acute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins
The Sequential Organ Failure Assessment (SOFA) score was significantly higher in the ARDS triggered by extrapulmonary injury (ARDSexp) group than in the ARDS triggered by pulmonary injury (ARDSp) group, measurements of the pulmonary vascular permeability index (PVPI) were significantly elevated in the ARDSp group on all days: at day 0 (2.9 ± 1.3 of ARDSexp vs. 3.3 ± 1.3 of ARDSp, p = .008), at day 1 (2.8 ± 1.5 of ARDSexp vs. 3.2 ± 1.2 of ARDSp, p = .01), at day 2 (2.4 ± 1.0 of ARDSexp vs. 2.9 ± 1.3 of ARDSp, p = .01)
The results of this study suggest the existence of several differences in the increased degree of pulmonary permeability between patients with ARDSexp and ARDSp

Summary

Introduction

Acute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins. Lung injuries of different origins may hold distinct pathophysiology, lung morphology, radiology, respiratory mechanics, and response to managements [5]. This distinction between an indirect and a direct etiology of lung injury is gaining more attention as a means of better comprehending the pathophysiology of ARDS and possibly for modifying ventilator management [6,7]. Gattinoni et al [6] measured the elastic properties of the lung and chest wall by using the quasistatic technique and reported that the differences in respiratory mechanics and response to positive endexpiratory pressure (PEEP) between patients with ARDSexp and those with ARDSp were predominantly due to collapse. We believe that more quantitative methods estimating the heterogeneity of ARDS at the initial stage and a customized therapy for each individual case may be helpful to appropriately manage ARDS patients

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