Pulmonary Function Is Better Preserved in Pigs When Acute Normovolemic Hemodilution Is Achieved With Hydroxyethyl Starch Versus Lactated Ringer's Solution

Abstract

Acute normovolemic hemodilution (ANH) has been proposed to decrease the need for allogenic blood transfusion. Consequently, great amounts of fluids are necessary to maintain hemodynamics during and after blood removal. The aim of this experiment was to evaluate the oxygenation, respiratory compliance, and lung structure during ANH performed with lactated Ringer's solution and hydroxyethyl starch (HES). Gas exchange, extravascular lung water, intrathoracic blood volume, serum osmolality, respiratory mechanics, and optical and electronic microscopy of lung biopsies were evaluated. Animals were randomized into three groups: CTL (control, n = 9), HES (HES 6% 200/0.5, n = 9), and LR (lactated Ringer's solution, n = 9). Animals in groups HES and LR underwent ANH to reach a preestablished hematocrit of around 15%. The removed blood was replaced with HES in a proportion of 1:1 and with lactated Ringer's solution 3:1. The LR group demonstrated a tendency for a marked time-dependence decrease in compliance (P = 0.013 in T2; P = 0.008 in T3) and in Pao2/fraction of inspired oxygen (Fio2) ratio (P = 0.033 in T2) as well as an increase in (A-a) Grad O2 (P = 0.037 in T2). Extravascular lung water and intrathoracic blood volume did not present any significant variation among the groups. In contrast, serum osmolality presented a significant decline in animals hemodiluted with lactated Ringer's solution. Optical and electronic microscopy of lungs biopsies revealed moderate to serious collapses and basement membrane enlargement in LR group. In this kind of experimental model, ANH with 6% HES (200/0.5) seems to preserve lung structure better as evidenced by maintenance of oxygenation indexes and respiratory compliance when compared with that in the Ringer's solution hemodiluted group.

Effects of Intravascular Volume Replacement on Lung and Kidney Function and Damage in Nonseptic Experimental Lung Injury

“…4 A recent meta-analysis 5 and different clinical trials 6,7 comparing the use of crystalloids versus colloids in critically ill patients found no differences in outcome. However, several beneficial effects of colloids compared to crystalloids have been shown in the lungs, namely reduced alveolar-capillary permeability, 8 less histological damage, 9 and decreased inflammatory cell infiltration. 10,11 Furthermore, colloids may allow faster hemodynamic stabilization compared to crystalloids.…”

Effects of hydroxyethyl starch resuscitation on extravascular lung water and pulmonary permeability in sepsis-related acute respiratory distress syndrome *

“…After fluid loading, the EVLW/PBV ratio was also related to PLI (r ϭ .43). As stated before, HES was not able to reduce vascular permeability, capillary leakage, and pulmonary edema in humans (34,(37)(38)(39) and animals (20,(23)(24)(25)(26)(27)40). Using the same 67 Gallium-transferrin PLI, Verheij et al (39) also clearly confirmed the ability of HES (200/0.5) for ameliorating the increased pulmonary permeability and pulmonary vascular injury caused by cardiac and major vascular surgery as compared with gelatin.…”

“…In human (34,(37)(38)(39) and animal (20,(23)(24)(25)(26)(27)40) studies a comparison of HES with crystalloids showed that HES maintained intravascular volume and COP in septic shock (35,36), and reduced vascular permeability, capillary leakage, and pulmonary edema. For the gelatin, the intravascular half-life is relatively short (about 2 hours) and volume expansion effect is low (plasma volume increased equal to the amount infused, with only half remaining after 4 hours) (41).…”

“…The effect of attenuating increased permeability has been translated to be improved preservation of pulmonary function with pentastarch than with gelofusine in patients undergoing abdominal aortic aneurysm surgery (57) or in pigs exposed to acute normovolemic hemodilution (40). However, few researchers have explored the effects of HES in ARDS with the greatest pulmonary permeability.…”

Volume Management and Resuscitation in Thoracic Surgery

“…Some beneficial effects on pulmonary parameters have been demonstrated, including pulmonary permeability [102,103], histological findings [104], reductions in VILI and pulmonary edema [105], and more rapid hemodynamic stabilization [103]. However, in a large systematic review of burns, trauma, and surgical patients, no outcome benefit of colloids could be demonstrated, and hydroxyethyl starch (HES) was found to possibly increase mortality [106].…”