Fluid therapy in patients with brain injury: what does physiology tell us?

Table 1 Physicochemical characteristics of available resuscitation fluid preparations

	Colloid	Specific gravity (g/ml)	H₂O content	Osmotic coefficient	Theoretical osmolarity (mosmol/l)	Real osmolality^a(mosmol/kg)	Tonicity
Plasma	Proteins	1.0258	0.940	0.926	291	287	Isotonic
NaCl 0.9%	None	1.0062	0.997	0.926	308	286	Isotonic
Dextrose 5%	None	1.0197	0.970	1.013	278	290	Isotonic (only in vitro)^b
Ringer’s lactate	None		0.997	0.926	276	256	Hypotonic
Ringer’s acetate	None		0.997	0.926	276	256	Hypotonic
Plasmalyte®	None		0.997	0.926	294	273	Hypotonic
Sterofundin® ISO/Isofundin®/Ringerfundin®^d	None		0.997	0.926	309	287^c	Isotonic
Voluven® 6%	6% HES 130/0.4	1.0274	0.958	0.926	308	298	Hypertonic (slightly)
Volulyte® 6%	6% HES 130/0.4	1.0274	0.956	0.926	287	278	Hypotonic (slightly)
Venofundin® 6%	6% HES 130/0.42	1.0257	0.957	0.926	308	298	Hypertonic (slightly)
Tetraspan® 6%	6% HES 130/0.42	1.0257	0.955	0.926	296	292^b	Isotonic
Gelafundin® 4%	4% polygeline	1.0177	0.969	0.926	274	262	Hypotonic
Gelafundin® ISO 4%	4% polygeline		0.969	0.926	284	271	Hypotonic
Albumex® 4%	4% human albumin		0.958	0.926	269	260	Hypotonic
Alburex® 5%	5% human albumin		0.948	0.926	281	274.5	Hypotonic (slightly)

^aOsmolality reflects the calculated, nominal osmolality (as calculated from osmolarity, water content and osmotic coefficient). ^bSince glucose is quickly metabolized and moved to the intracellular compartment, dextrose solutions behave severely hypotonic in vivo. ^cConsidering that one malate anion is metabolized to two hydrogen carbonate anions. ^dSterofundin ISO, Isofundin and Ringerfundin represent different labels for equivalent solutions. HES, hydroxyethyl starch. Modified from Physioklin [19].

ISSN: 1364-8535