Plasma Volume Expansion with 5% Albumin Compared to Ringer’s Acetate during Normal and Increased Microvascular Permeability in the Rat

Abstract

• It is thought that the better volume-expanding effect of albumin relative to crystalloids is dependent on low endothelial permeability for albumin What This Article Tells Us That Is New• One group of animals were subjected to a 11% hemorrhage and then given either 5% albumin in a volume equal to the shed blood volume or Ringer's acetate at 4.5 times that volume • Another group of animals were subjected to abdominal sepsis, and at 3 h, measured plasma volume loss was replaced with either 5% albumin or with Ringer's acetate in 4.5 times the measured loss • Plasma volume expansion with albumin relative to Ringer's acetate did not differ between the two groups despite different etiologies for the decrease in plasma volume ABSTRACT Background: It is believed that the effectiveness of colloids as plasma volume expanders is dependent on the endothelial permeability for macromolecules. The objective of this study was to test the hypothesis that the plasma volume expanding effect of 5% albumin relative to that of a crystalloid solution is reduced if microvascular permeability is increased. Methods: A control group was resuscitated with either 5% albumin (8 ml/kg) or Ringer's acetate (36 ml/kg) immediately after a hemorrhage of 8 ml/kg (n = 29). In a second group, permeability was increased by inducing sepsis through cecal ligation and incision (n = 28). Three hours after cecal ligation and incision, the animals were resuscitated with either 5% albumin in a ratio of 1:1 relative to the volume of lost plasma, or Ringer's acetate in a ratio of 4.5:1. Results: In the hemorrhage group, plasma volumes at 15 min after resuscitation with albumin or Ringer's acetate had increased by 9.8 ± 2.6 ml/kg (mean ± SD) and 7.4 ± 2.9 ml/kg and were similar at 2 and 4 h. Plasma volume 3 h after cecal ligation and incision had decreased by approximately 7 ml/kg, and at 15 min after resuscitation with albumin or Ringer's acetate it had increased by 5.7 ± 2.9 and 2.4 ± 3.0 ml/kg, respectively (P < 0.05). At 2 and 4 h after resuscitation, plasma volumes did not differ between the groups. Conclusion: This study does not support the hypothesis that the plasma-volume-expanding effect of albumin relative to that of crystalloids is decreased under conditions characterized by increased permeability. ( Anesthesiology 2014; 121:817-24)The first two authors contributed equally to the study.

Effect of Ringer’s acetate in different doses on plasma volume in rat models of hypovolemia

“…Measurement of plasma volume using radiolabeled albumin is considered to be a golden standard and both baseline values and values after CLP in the present study are very similar to those reported in previous studies supporting the reliability of the methodology [ 14 , 19 , 20 ]. Sources of error, such as changes in the rate of extravasation of albumin secondary to increases in permeability, and amount of free iodine has been analyzed in detail previously [ 14 ] and it has been concluded that these sources of error are small during the present experimental conditions. Furthermore, our finding of reciprocal changes in hematocrit also supports the reliability of the plasma volume measurements.…”

“…Based on this, it could be hypothesized that crystalloids are less potent as plasma volume expanders during inflammatory conditions. Results showing that only 1–9% of a crystalloid remain intravascularly immediately after resuscitation in experimental sepsis [ 13 , 14 ] or in postoperative cardiac surgery patients, align with this hypothesis [ 15 ]. These results raise the following questions: Can normovolemia be achieved with a crystalloid-based resuscitation strategy in severe inflammation?…”

“…Following baseline measurements (see Fig. 1 ), animals were subjected to a cecal ligation and puncture (CLP) procedure as described previously [ 14 ]. Four hours after the CLP procedure, plasma volume was measured again and the change in plasma volume was calculated.…”

“…Change in plasma volume at 15 min after resuscitation was the primary outcome. Because of the exploratory nature of these experiments, no formal power analysis was performed and the group size was based on previous studies in which differences in plasma volume expansion could be detected using the same methodology [ 13 , 14 ]. Randomization was performed in blocks of four in each of the treatment groups with the objective to have eight to ten animals in each group.…”

Effects of fresh frozen plasma, Ringer’s acetate and albumin on plasma volume and on circulating glycocalyx components following haemorrhagic shock in rats

“…This means that an increased extravascular distribution volume of crystalloids secondary to a shock-induced SIRS response could explain the low efficacy of crystalloids as plasma volume expanders and such a change in the interstitium has been hypothesized to be an important contributor to inflammation-induced oedema formation [ 20 ]. Support for this mechanism in inflammatory conditions may be found in a recent publication from our group in which we found that at 15 min after resuscitation in severe sepsis, only about 8 % of the infused volume of crystalloids remained intravascular [ 21 ].…”