The review focuses on fluid resuscitation of critically ill patients with either colloid or crystalloid solutions.
In healthy patients, the volume expanding effect of colloids is greater than that of crystalloids. However, in critically ill patients, a similar amount of crystalloids and colloids is required for fluid resuscitation, suggesting a lower efficiency of colloids when capillary permeability is increased, and endothelial glycocalyx disrupted. Recent studies on synthetic colloids in surgical patients confirmed the increased risk of renal failure reported in large clinical trials performed in critically ill patients. Experimental studies suggest that albumin maintains plasma volume expansion efficiency even when the capillary permeability is impaired, and that extravasation of albumin to the interstitium is lower than that of hydroxyethyl starch.
Fluid administration should be tailored to patient characteristics. Synthetic colloids should be avoided when possible, especially in patients at risk for kidney injury. In critically ill patients with suspected increased permeability, colloids may not be superior to crystalloids in expanding plasma volume. Albumin appears to be less harmful than synthetic colloids, although its beneficial effects need to be further investigated. The endothelial glycocalyx layer is the key structure finely regulating intravascular fluid distribution.
aDipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Fondazione IRCCS Ca’ Granda – Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
bDepartment of Anesthesiology and Intensive Care Medicine, Georg-August-University Göttingen, Göttingen, Germany
cDipartimento di Anestesia, Rianimazione ed Emergenza Urgenza, Fondazione IRCCS Ca’ Granda – Ospedale Maggiore Policlinico, Milan, Italy
Correspondence to Pietro Caironi, MD, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Fondazione IRCCS Ca’ Granda – Ospedale Maggiore Policlinico, Università degli Studi di Milano, Via F. Sforza 35, 20122 Milan, Italy. Tel: +39 02 5503 3232/3231; fax: +39 02 55033230; e-mail: firstname.lastname@example.org