Rheologic Effects of Plasma Substitutes Used for Preoperative Hemodilution

Abstract

This study was designed to compare the influence of various plasma substitutes, administered for preoperative hemodilution, on blood rheology. We studied 40 patients, ASA grade I, who underwent elective facial reconstructive surgery and received 4% albumin (n = 10), 3.5% dextran 40 (n = 10), gelatin (n = 10), or hydroxyethyl starch (HES) (n = 10). Ten patients, undergoing the same surgical procedure without hemodilution, were chosen as controls. After hemodilution, hematocrit was decreased approximately 30%. Fibrinogen decreased in all tested groups except in the gelatin group. Plasma viscosity decreased with albumin (1.13 +/- 0.05 to 1.06 +/- 0.03 mPa.s; P < 0.01) and increased with HES (1.15 +/- 0.04 to 1.22 +/- 0.05 mPa.s; P < 0.01). At a high shear rate, the blood viscosity decreased in all groups. In contrast, at a low shear rate and at 40% corrected hematocrit, the blood viscosity decreased in the albumin (15.9 +/- 1.9 to 13.1 +/- 2.1 mPa.s; P < 0.01) and the dextran 40 (16.9 +/- 2.9 to 12.8 +/- 2.5 mPa.s; P < 0.01) groups and was unchanged in the gelatin and the HES groups. Erythrocyte aggregation (measured with primary aggregation time) was markedly decreased in the albumin (3.27 +/- 1.74 to 7.03 +/- 2.95 s; P < 0.01) and in the dextran 40 (2.72 +/- 0.58 to 6.24 +/- 2.55 s; P < 0.001) groups, unchanged with HES, and increased with gelatin (2.41 +/- 0.90 to 1.55 +/- 0.33 s). These findings suggest that albumin and dextran 40 may be the plasma substitutes of choice for preoperative hemodilution when this technique aims to improve rheologic conditions.

Hypertonic fluid resuscitation from subarachnoid hemorrhage in rats: A comparison between small volume resuscitation and mannitol

“…Comparably, we could show a transient significant increase of ipsilateral CBF in the 7.5% NaCl + dextran 70 group. Possible reasons for the improved LCBF in the dextran-treated group could be viscosity-enhancing effects of dextran [25] or a sustained inhibition of an endothelium -leucocyte interaction by dextran solution in contrast to HES [24], leading to an improved perfusion and LCBF of the examined tissue. The improved MABP and the resulting elevated CPP due to volume expanding effects of SVR could also contribute to the improved LCBF in group II.…”

“…Dextrans have been shown to elicit distinct pharmacologic properties, especially with regard to reducing the erythrocyte aggregation, blood viscosity and improving arterio-venous oxygen difference [25,68]. Dextran is also able to reduce the hydraulic conductivity of blood vessels and to reduce the formation of edema in the brain [69].…”

“…Various studies showed that hypertonic saline solutions with or without the addition of colloid substances were able to ameliorate intracranial hypertension [15,17,18,22,23], whereas differences concerning their efficacy [15,17,22,23] were demonstrated. In addition, there are indications that dextran, hydroxyethylstarch (HES) and mannitol have different effects concerning inhibition of leucocyte -endothelium interactions [24], influence on plasma viscosity [25], CBF, ICP [18,26,27] and blood rheology [28,29].…”

Anesthetic management of a patient with polycythemia vera for neurosurgery

“…To take into account intraoperative blood loss and the potential for an acute hemodynamic event, we collected 700 ml of blood following consultation with the hematologist. As colloids can increase the viscosity of blood, we used crystalloids under TEE guidance for volume replacement [5,7]. Dehydration increases plasma viscosity, erythrocyte aggregation and RBC rigidity and decreases oxygen delivery [8].…”

0.9% saline solution: “physiological” or “unphysiological”?

“…Anaphylactic phenomena have been described with all the semi-synthetic colloids and albumin: the incidence of severe events is increased with gelatine (<0.35%) and dextrans (<0.28%) compared to albumin (<0.1%) and the HES (<0.06) [12,13].…”