Acute Normovolemic Hemodilution in the Pig Is Associated with Renal Tissue Edema, Impaired Renal Microvascular Oxygenation, and Functional Loss

Article · June 2013with23 Reads
DOI: 10.1097/ALN.0b013e31829bd9bc · Source: PubMed
Abstract
The authors investigated the impact of acute normovolemic hemodilution (ANH) on intrarenal oxygenation and its functional short-term consequences in pigs. Renal microvascular oxygenation (µPO2) was measured in cortex, outer and inner medulla via three implanted optical fibers by oxygen-dependent quenching of phosphorescence. Besides systemic hemodynamics, renal function, histopathology, and hypoxia-inducible factor-1α expression were determined. ANH was performed in n = 18 pigs with either colloids (hydroxyethyl starch 6% 130/0.4) or crystalloids (full electrolyte solution), in three steps from a hematocrit of 30% at baseline to a hematocrit of 15% (H3). ANH with crystalloids decreased µPO2 in cortex and outer medulla approximately by 65% (P < 0.05) and in inner medulla by 30% (P < 0.05) from baseline to H3. In contrast, µPO2 remained unaltered during ANH with colloids. Furthermore, renal function decreased by approximately 45% from baseline to H3 (P < 0.05) only in the crystalloid group. Three times more volume of crystalloids was administered compared with the colloid group. Alterations in systemic and renal regional hemodynamics, oxygen delivery and oxygen consumption during ANH, gave no obvious explanation for the deterioration of µPO2 in the crystalloid group. However, ANH with crystalloids was associated with the highest formation of renal tissue edema and the highest expression of hypoxia-inducible factor-1α, which was mainly localized in distal convoluted tubules. ANH to a hematocrit of 15% statistically significantly impaired µPO2 and renal function in the crystalloid group. Less tissue edema formation and an unimpaired renal µPO2 in the colloid group might account for a preserved renal function.
    • However, it must be noted that pathophysiology in critically ill patients differs markedly from surgical patients. Recent work has demonstrated that haemodilution with colloids leads to less renal injury than crystalloid haemodilution [17], and two meta-analyses in surgical patients concluded that there was no increase in the incidence of postoperative death and/or renal dysfunction with the use of HES 6% 130/0.4 [18, 19].
    [Show abstract] [Hide abstract] ABSTRACT: We compared the effects on microvascular reactivity of hydroxyethylstarch (Volulyte(®) ) and gelatin (Geloplasma(®) ) during acute haemodilution. The hypothesis was that Volulyte would provide better microvascular reactivity than Geloplasma. Forty patients undergoing elective cardiac surgery were randomly assigned to receive either Volulyte or Geloplasma as the exclusive priming solution of the cardiopulmonary bypass. To evaluate microvascular reactivity, postocclusive reactive hyperaemia was examined before and after cardiopulmonary bypass. Microvascular reactivity assessments included the rate of the occlusion and reperfusion slopes and reperfusion times. After cardiopulmonary bypass, increases in reperfusion time were significantly smaller in the Volulyte group (3 (-27 to 9 [-35 to 33]%) vs 29 (-17 to 76 [-34 to 137]%) in the Geloplasma group, p = 0.02 between groups). Rate of reperfusion increased in the Volulyte group (26 (-17 to 43 [-59 to 357])%), whereas it decreased in the Geloplasma group (-22 (-47 to 16 [-84 to 113])%), p = 0.02 between groups. The shorter reperfusion times and increased reperfusion rate suggest that Volulyte maintains better microvascular reactivity than Geloplasma.
    Article · Feb 2016
    • From a physiological viewpoint, a hematocrit level of 30% was considered to be an optimal target within the prevention measures for SAKI.[27]A recent retrospective study, however, showed that red blood cell transfusion in non-bleeding critically ill patients with moderate anemia and without shock was associated with higher nosocomial infection rates, more AKI and increased mortality.[28]This
    [Show abstract] [Hide abstract] ABSTRACT: Sepsis-induced acute kidney injury (SAKI) remains an important challenge for intensive care unit clinicians. We reviewed current available evidence regarding prevention and treatment of SAKI thereby incorporating some major recent advances and developments. Prevention includes early and ample administration of “balanced” crystalloid solutions such as Ringer’s lactate. For monitoring of renal function during resuscitation, lactate clearance rate is preferred above ScvO2 or renal Doppler. Aiming at high central venous pressures seems to be deleterious in light of the novel “kidney afterload” concept. Noradrenaline is the vasopressor of choice for preventing SAKI. Intra-abdominal hypertension, a potent trigger of acute kidney injury in postoperative and trauma patients, should not be neglected in sepsis. Renal replacement therapy (RRT) must be started early in fluid-overloaded patients refractory to diuretics. Continuous RRT (CRRT) is the preferred modality in hemodynamically unstable SAKI but its use in more stable SAKI is increasing. In the absence of hypervolemia, diuretics should be avoided. Antimicrobial dosing during CRRT needs to be thoroughly reconsidered to assure adequate infection control.
    Full-text · Article · Apr 2013
  • [Show abstract] [Hide abstract] ABSTRACT: Sepsis-induced acute kidney injury (SAKI) remains an important challenge in critical care medicine. We reviewed current available evidence on prevention and treatment of SAKI with focus on some recent advances and developments. Prevention of SAKI starts with early and ample fluid resuscitation preferentially with crystalloid solutions. Balanced crystalloids have no proven superior benefit. Renal function can be evaluated by measuring lactate clearance rate, renal Doppler, or central venous oxygenation monitoring. Assuring sufficiently high central venous oxygenation most optimally prevents SAKI, especially in the post-operative setting, whereas lactate clearance better assesses mortality risk when SAKI is present. Although the adverse effects of an excessive “kidney afterload” are increasingly recognized, there is actually no consensus regarding an optimal central venous pressure. Noradrenaline is the vasopressor of choice for preventing SAKI. Intra-abdominal hypertension, a potent trigger of AKI in post-operative and trauma patients, should not be neglected in sepsis. Early renal replacement therapy (RRT) is recommended in fluid-overloaded patients’ refractory to diuretics but compelling evidence about its usefulness is still lacking. Continuous RRT (CRRT) is advocated, though not sustained by convincing data, as the preferred modality in hemodynamically unstable SAKI. Diuretics should be avoided in the absence of hypervolemia. Antimicrobial dosing during CRRT needs to be thoroughly reconsidered to assure adequate infection control.
    Full-text · Article · Jan 2013
  • Article · May 2013
  • [Show abstract] [Hide abstract] ABSTRACT: Compared with goal-directed crystalloid therapy, goal-directed colloid therapy during high-risk surgery may improve postoperative outcome. Whether intraoperative fluid therapy based on goal-directed protocol with different types of fluid has distinctive effects on brain relaxation and cerebral metabolism during craniotomy remains unclear. Forty patients with supratentorial brain tumors undergoing craniotomy were randomly assigned to either a Ringer's Lactate-based goal-directed group (LR group, n=20) or a 6% hydroxyethyl starch-based goal-directed group (HES group, n=20). The goal was achieved by maintaining a target stroke volume variation (SVV<13%) by volume loading with LR or HES throughout the procedure. The primary outcome is brain relaxation scales, an indirect evaluation of ICP; secondary endpoints include cerebral metabolism variables (jugular venous oxygen saturation [SjvO2], arterial-jugular venous differences in oxygen [CajvO2], glucose [A-JvGD], lactate [A-JvLD], and cerebral extraction ratio for oxygen [CERO2]) and fluid volumes. There is no significant difference between the LR and HES groups on brain relaxation scales (P=0.845), or measures of cerebral oxygenation and metabolism. Intragroup comparisons showed that CERO2 increased by 14.3% (P=0.009, LR group) and 13.2% (P=0.032, HES group), respectively, and SjvO2 was decreased by 8.8% (P=0.016, LR group) and 8.1% (P=0.026, HES group), respectively, after tumor removal, compared with baseline. During surgery, the LR group (3070±1138 mL) received more fluid than the HES group (2041±758 mL, P=0.002). In patients undergoing supratentorial tumor resection, goal-directed HES therapy was not superior to goal-directed LR therapy for brain relaxation or cerebral metabolism, although less fluid was needed to maintain the target SVV in the HES-based group than in the LR-based group.
    Article · Jan 2014
  • Article · Apr 2014
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