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Open Access Highly Accessed Research

Mechanical ventilation worsens abdominal edema and inflammation in porcine endotoxemia

Marco Lattuada12, Maria Bergquist3, Enn Maripuu4 and Göran Hedenstierna5*

Author Affiliations

1 Department of Medical Sciences, Clinical Physiology, Hedenstierna Laboratory, Uppsala University, Sweden

2 Department of Anesthesia and Intensive Care, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy

3 Department of Medical Sciences, Clinical Physiology, Hedenstierna Laboratory, Uppsala University, Sweden

4 Department of Medical Physics, University Hospital, Uppsala, Sweden

5 Department of Medical Sciences, Clinical Physiology, Hedenstierna Laboratory, Uppsala University, Sweden

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Critical Care 2013, 17:R126  doi:10.1186/cc12801

Published: 24 June 2013

Abstract

Introduction

We hypothesized that mechanical ventilation per se increases abdominal edema and inflammation in sepsis and tested this in experimental endotoxemia.

Methods

Thirty anesthetized piglets were allocated to one of five groups: healthy control pigs breathing spontaneously with continuous positive pressure of 5 cm H2O or mechanically ventilated with positive end-expiratory pressure of 5 cm H2O, and endotoxemic piglets during mechanical ventilation for 2.5 hours and then continued on mechanical ventilation with positive end-expiratory pressure of either 5 or 15 cm H2O or switched to spontaneous breathing with continuous positive pressure of 5 cm H2O for another 2.5 hours. Abdominal edema formation was estimated by isotope technique, and inflammatory markers were measured in liver, intestine, lung, and plasma.

Results

Healthy controls: 5 hours of spontaneous breathing did not increase abdominal fluid, whereas mechanical ventilation did (Normalized Index increased from 1.0 to 1.6; 1 to 3.3 (median and range, P < 0.05)). Endotoxemic animals: Normalized Index increased almost sixfold after 5 hours of mechanical ventilation (5.9; 4.9 to 6.9; P < 0.05) with twofold increase from 2.5 to 5 hours whether positive end-expiratory pressure was 5 or 15, but only by 40% with spontaneous breathing (P < 0.05 versus positive end-expiratory pressure of 5 or 15 cm H2O). Tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 in intestine and liver were 2 to 3 times higher with mechanical ventilation than during spontaneous breathing (P < 0.05) but similar in plasma and lung. Abdominal edema formation and TNF-α in intestine correlated inversely with abdominal perfusion pressure.

Conclusions

Mechanical ventilation with positive end-expiratory pressure increases abdominal edema and inflammation in intestine and liver in experimental endotoxemia by increasing systemic capillary leakage and impeding abdominal lymph drainage.