Hypervolemia increases release of atrial natriuretic peptide and shedding of the endothelial glycocalyx.

Daniel Chappell,Markus Rehm,Florian Brettner,Michael Vogeser,Julia Potzel,Peter Conzen,Matthias Jacob,Bernhard F Becker,Dirk Bruegger

doi:10.1186/s13054-014-0538-5

Abstract

IntroductionAcute normovolemic hemodilution (ANH) and volume loading (VL) are standard blood-sparing procedures. However, VL is associated with hypervolemia, which may cause tissue edema, cardiopulmonary complications and a prolonged hospital stay. The body reacts to hypervolemia with release of atrial natriuretic peptide (ANP) from the heart. ANP has been shown to deteriorate the endothelial glycocalyx, a vital part of the vascular permeability barrier. The aim of the present study was to evaluate and compare ANP release and damage to the glycocalyx during ANH and VL.MethodsANH or VL with 6% hydroxyethyl starch 130/0.4 was administered prior to elective surgery in patients of good cardiopulmonary health (n =9 in each group). We measured concentrations of ANP in plasma and of three main constituent parts of the glycocalyx (hyaluronan, heparan sulfate and syndecan 1) in serum before and after ANH or VL. Heparan sulfate and syndecan 1 levels in urine were also determined.ResultsIn contrast to ANH, VL (20 ml/kg) induced a significant release of ANP (approximately +100%, P <0.05) and increased the serum concentration of two glycocalyx constituents, hyaluronan and syndecan 1 (both by about 80%, P <0.05). Elevation of syndecan 1 was also detected in the urine of patients undergoing VL, but no increase was found in patients undergoing ANH. Heparan sulfate levels were not influenced by either procedure.ConclusionThese data suggest that hypervolemia increases the release of ANP and causes enhanced shedding of the endothelial glycocalyx. This perturbation must be expected to impair the vascular barrier, implying that VL may not be as safe as generally assumed and that it should be critically evaluated.

Highlights

Acute normovolemic hemodilution (ANH) and volume loading (VL) are standard blood-sparing procedures
Elevation of syndecan 1 was detected in the urine of patients undergoing VL, but no increase was found in patients undergoing ANH
These data suggest that hypervolemia increases the release of atrial natriuretic peptide (ANP) and causes enhanced shedding of the endothelial glycocalyx

Summary

Introduction

Acute normovolemic hemodilution (ANH) and volume loading (VL) are standard blood-sparing procedures. VL is associated with hypervolemia, which may cause tissue edema, cardiopulmonary complications and a prolonged hospital stay. ANP has been shown to deteriorate the endothelial glycocalyx, a vital part of the vascular permeability barrier. Hypervolemia has been shown to have detrimental influences on several aspects of patient outcome, including cardiopulmonary complications, anastomotic insufficiency, length of hospital stay, duration of mechanical ventilation and mortality [9,10,11]. ANP is known to induce rapid shifts of intravascular fluid into the interstitial space and has been shown to cause deterioration of the endothelial glycocalyx. In an isolated heart model, artificially infused ANP induced an increase in vascular permeability, a histologically detectable degradation of the glycocalyx and significant tissue edema [13]. An increase in plasma ANP has been found to precede shedding of the glycocalyx in patients undergoing coronary bypass surgery [14]

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