A quantitative CT parameter for the assessment of pulmonary oedema in patients with acute respiratory distress syndrome.

Patrick Leiser,Stefan Schoenberg,Michael Hagmann,Daniel Overhoff,Claudia Henzler,Christel Weiß,Philipp Riffel,Thomas Kirschning,Holger Haubenreisser,Jochen Schoettler,Franz-Simon Centner,Thomas Henzler,Sonja Janssen,Andrea Coppadoro

doi:10.1371/journal.pone.0241590

Patrick Leiser, Stefan Schoenberg + Show 12 more

Open Access

https://doi.org/10.1371/journal.pone.0241590

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Abstract

ObjectivesThe aim of this study was to establish quantitative CT (qCT) parameters for pathophysiological understanding and clinical use in patients with acute respiratory distress syndrome (ARDS). The most promising parameter is introduced.Materials and methods28 intubated patients with ARDS obtained a conventional CT scan in end-expiratory breathhold within the first 48 hours after admission to intensive care unit (ICU). Following manual segmentation, 137 volume- and lung weight-associated qCT parameters were correlated with 71 clinical parameters such as blood gases, applied ventilation pressures, pulse contour cardiac output measurements and established status and prognosis scores (SOFA, SAPS II).ResultsOf all examined qCT parameters, excess lung weight (ELW), i.e. the difference between a patient’s current lung weight and the virtual lung weight of a healthy person at the same height, displayed the most significant results.ELW correlated significantly with the amount of inflated lung tissue [%] (p<0.0001; r = -0.66) and was closely associated with the amount of extravascular lung water (EVLW) (p<0.0001; r = 0.72). More substantially than the oxygenation index (PaO2/FiO2) or any other clinical parameter it correlated with the patients’ mean SOFA- (p<0.0001, r = 0.69) and SAPS II-Score (p = 0.0005, r = 0.62). Patients who did not survive intensive care treatment displayed higher values of ELW in the initial CT scans.ConclusionsELW could serve as a non-invasive method to quantify the amount of pulmonary oedema. It might serve as an early radiological marker of severity in patients with ARDS.

Highlights

137 volume- and lung weight-associated quantitative CT (qCT) parameters were correlated with 71 clinical parameters such as blood gases, applied ventilation pressures, pulse contour cardiac output measurements and established status and prognosis scores (SOFA, Simplified Acute Physiology Score II’ (SAPS II))
Excess lung weight (ELW) could serve as a non-invasive method to quantify the amount of pulmonary oedema
It might serve as an early radiological marker of severity in patients with acute respiratory distress syndrome (ARDS)

Summary

Introduction

It can be caused by various pulmonary and extrapulmonary triggering factors, the most common being pneumonia and sepsis. Under the assumption that lung density differs within the range of gas (-1000 Hounsfield Units, HU) and water (0 HU), each voxel can be assigned to a certain degree of aeration [1]. The selection of multiple voxels allows the measurement of various volume- or lung weight-associated parameters [1]. Dynamic CT scans enabled the quantitative analysis of recruitment and derecruitment throughout the ventilation cycle [3] This led to an increased knowledge on ARDS pathophysiology revealing disease modifying factors such as gravity [4], positive end-expiratory pressure (PEEP) [5] and prone positioning [6]

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