open access

Vol 47, No 5 (2015)
Review articles
Published online: 2015-10-12
Submitted: 2015-08-14
Accepted: 2015-10-02
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Must hypervolaemia be avoided? A critique of the evidence

Robert G. Hahn
DOI: 10.5603/AIT.a2015.0062
·
Anaesthesiol Intensive Ther 2015;47(5):449-456.

open access

Vol 47, No 5 (2015)
Review articles
Published online: 2015-10-12
Submitted: 2015-08-14
Accepted: 2015-10-02

Abstract

Anaesthetists are cautioned to avoid hypervolaemia in their patients. The most cited reason is that hypervolaemia elicits the release of atrial natriuretic peptides that damage the endothelial glycocalyx layer. Although shedding of the glycocalyx causes extravasation of protein in inflammatory disorders, it is more uncertain whether hypervolaemia alone is enough to cause clinically important shedding.

This review scrutinises the methodology used in two key papers that propose such a link. The most cited one reports that hydroxyethyl starch and 5% albumin, when creating a hypervolaemic state, only expands the plasma by 40% of the infused volume. This result was obtained by comparing measurements of the plasma volume performed with the indocyanine green (ICG) dye method before and after the infusion. However, the transit time of the dye, as well as inequality in the concentration between vascular beds, both act to underestimate the plasma volume, particularly as times were extrapolated backwards to time zero instead of to (the more correct) 1 minute.

A re-calculation based on theoretical ICG data, taking account of the transit time, shows the plasma volume expansion was closer to 100% than to 40% of the infused volume.

This figure is supported by the dilution of the reported blood haemoglobin and plasma protein concentrations, as well as by other sources. In conclusion, only weak evidence supports a fluid-induced release of atrial peptides of sufficient size to alter the kinetics of colloid fluid by shedding of the endothelial glycocalyx layer.

Abstract

Anaesthetists are cautioned to avoid hypervolaemia in their patients. The most cited reason is that hypervolaemia elicits the release of atrial natriuretic peptides that damage the endothelial glycocalyx layer. Although shedding of the glycocalyx causes extravasation of protein in inflammatory disorders, it is more uncertain whether hypervolaemia alone is enough to cause clinically important shedding.

This review scrutinises the methodology used in two key papers that propose such a link. The most cited one reports that hydroxyethyl starch and 5% albumin, when creating a hypervolaemic state, only expands the plasma by 40% of the infused volume. This result was obtained by comparing measurements of the plasma volume performed with the indocyanine green (ICG) dye method before and after the infusion. However, the transit time of the dye, as well as inequality in the concentration between vascular beds, both act to underestimate the plasma volume, particularly as times were extrapolated backwards to time zero instead of to (the more correct) 1 minute.

A re-calculation based on theoretical ICG data, taking account of the transit time, shows the plasma volume expansion was closer to 100% than to 40% of the infused volume.

This figure is supported by the dilution of the reported blood haemoglobin and plasma protein concentrations, as well as by other sources. In conclusion, only weak evidence supports a fluid-induced release of atrial peptides of sufficient size to alter the kinetics of colloid fluid by shedding of the endothelial glycocalyx layer.

Get Citation

Keywords

clinical pharmacology; fluid therapy, therapeutic use; glycocalyx, physiology; hydroxyethyl starch, pharmacokinetics; indicator dilution technique, method

About this article
Title

Must hypervolaemia be avoided? A critique of the evidence

Journal

Anaesthesiology Intensive Therapy

Issue

Vol 47, No 5 (2015)

Pages

449-456

Published online

2015-10-12

DOI

10.5603/AIT.a2015.0062

Bibliographic record

Anaesthesiol Intensive Ther 2015;47(5):449-456.

Keywords

clinical pharmacology
fluid therapy
therapeutic use
glycocalyx
physiology
hydroxyethyl starch
pharmacokinetics
indicator dilution technique
method

Authors

Robert G. Hahn

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