An in vitro lung model to assess true shunt fraction by multiple inert gas elimination.

Balamurugan Varadarajan,Jolanda Consiglio,Rakesh Vasireddy,Balthasar Eberle,Andreas Vogt,Volker Hartwich,Beate Hugi-Mayr

doi:10.1371/journal.pone.0184212

Balamurugan Varadarajan, Jolanda Consiglio + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0184212

Copy DOI

Journal: PloS one	Publication Date: Sep 6, 2017
Citations: 1	License type: CC BY 4.0

Affiliation: University Hospital of Bern, University of Bern

Abstract

The Multiple Inert Gas Elimination Technique, based on Micropore Membrane Inlet Mass Spectrometry, (MMIMS-MIGET) has been designed as a rapid and direct method to assess the full range of ventilation-to-perfusion (V/Q) ratios. MMIMS-MIGET distributions have not been assessed in an experimental setup with predefined V/Q-distributions. We aimed (I) to construct a novel in vitro lung model (IVLM) for the simulation of predefined V/Q distributions with five gas exchange compartments and (II) to correlate shunt fractions derived from MMIMS-MIGET with preset reference shunt values of the IVLM. Five hollow-fiber membrane oxygenators switched in parallel within a closed extracorporeal oxygenation circuit were ventilated with sweep gas (V) and perfused with human red cell suspension or saline (Q). Inert gas solution was infused into the perfusion circuit of the gas exchange assembly. Sweep gas flow (V) was kept constant and reference shunt fractions (IVLM-S) were established by bypassing one or more oxygenators with perfusate flow (Q). The derived shunt fractions (MM-S) were determined using MIGET by MMIMS from the retention data. Shunt derived by MMIMS-MIGET correlated well with preset reference shunt fractions. The in vitro lung model is a convenient system for the setup of predefined true shunt fractions in validation of MMIMS-MIGET.

Highlights

The worldwide volume of major surgical procedures is estimated at 243 million per year [1]
The specific aims of this study were (I) to design an in vitro lung model (IVLM) with five separate gas exchange compartments connected in parallel to achieve resolution of shunt fractions between 0.0 and 1.0, and (II) to compare shunt fractions derived from membrane inlet mass spectrometry (MMIMS)-multiple inert gas elimination technique (MIGET) with preset reference shunt fractions of the IVLM (IVLM-S)
Duplicate samples were taken at each reference shunt setting; 10 samples were taken at five different time points

Summary

Introduction

The worldwide volume of major surgical procedures is estimated at 243 million per year [1]. Morbidity and mortality after major surgery are associated with postoperative pulmonary complications like lung injury and acute respiratory distress syndrome (ARDS) [2, 3]. A worldwide multicenter observational study yielded a prevalence of ARDS due to all causes of 10.5% among ICUs in 50 countries [4]. The Berlin definition of ARDS introduced a mild (200mmHg < PaO2/FIO2 300mmHg), moderate (100mmHg < PaO2/FIO2 200mmHg) and severe oxygenation stage (PaO2/FIO2 100mmHg) of the syndrome [5]. ARDS hospital mortality of mild stage was 34.9%, of moderate stage 40.3% and of severe stage 46.1% [4, 6]. There was evidence of under recognition and under treatment of this globally public

Objectives

Methods

Results

Discussion

Conclusion