THE INFLUENCE OF RINGER LACTATE AND GELATIN INFUSION ON THE INTERNAL FLUID BALANCE OF HEALTHY-VOLUNTEERS MEASURED BY A NONINVASIVE CONDUCTIVITY TECHNIQUE

Eight healthy male volunteers received in random order at an interval of 1 week 2 litres of Ringer's lactate or 0.8 litre of gelatin (Gelofu sine(R)) over half an hour, after overnight fasting. At the end of the infusion period, blood volume and mean arterial pressure had increase d significantly in both groups but the increase in blood volume was mo re pronounced with the colloid. Extracellular fluid volume increased s ignificantly after Ringer's lactate, while a significant decrease was noticed after gelatin. A small decrease in intracellular fluid volume was noted after infusion of Gelofusine(R), whereas it did not change a fter infusion of Ringer's lactate. During the 30 min after infusion, b lood volume decreased significantly after both treatments but after th e colloid it remained higher than the initial value. During the post-i nfusion period, no significant changes in either intra- or extracellul ar volume were seen after either treatments. At the end of the study, urine production was significantly more after the Ringer's lactate. It can be concluded that infusion of 0.8 litre of gelatin results in a l arger and longer lasting increase in blood volume than 2 litres of Rin ger's lactate, probably due to mobilization of extracellular fluid vol ume. It also leads to extracellular fluid accumulation. The decrease i n blood volume after infusion is caused by increased urine production, since no changes were seen in intra- and extracellular fluid volume d uring this period.