Comparison of Malated Ringer's with Two Other Balanced Crystalloid Solutions in Resuscitation of Both Severe and Moderate Hemorrhagic Shock in Rats

Influence of acetate- vs. lactate-containing fluid bolus therapy on acid-base status, electrolytes, and plasma lactate in dogs

Objective

Acetate- and lactate-containing fluids influence the acid-base and electrolyte status. This prospective, randomized, clinical study compared two balanced crystalloid solutions regarding their influence on acid-base status, electrolytes, and lactate values, when given to dogs as a resuscitation bolus of 30 mL/kg.

Material and methods

One hundred client-owned dogs presenting to the emergency service with signs of fluid deficits were randomly assigned to receive an intravenous bolus of 30 mL/kg of either a lactate- (LAC), or an acetate-containing solution (ACET). Before and after the bolus, vital parameters were assessed, and a venous blood gas analysis was performed.

Results

Both solutions performed equally well in decreasing the heart rate (ACET: −10 ± 27 bpm, LAC: −12 ± 30 bpm; p = 0.737). The acetate-containing solution caused a significant decrease in plasma lactate levels (p = 0.016), anion gap (p < 0.001), and potassium (p < 0.001), and a significant increase in chloride (p < 0.001), and ionized calcium (p = 0.014). The lactate-containing solution caused a significant decrease in anion gap (p < 0.001), sodium (p = 0.016), and potassium (p = 0.001), and a significant increase in chloride (p < 0.001). ACET causes a stronger decrease in plasma lactate (p = 0.015), sodium (p = 0.039), potassium (p = 0.006), and an increase in chloride (p < 0.001), and ionized calcium (p = 0.016) compared to LAC.

Conclusion

Both solutions caused mild changes in electrolyte concentrations and had minor influence on acid-base status when used for bolus therapy in dogs with fluid deficits. Further studies are needed to evaluate their influence on acid-base status, lactate, and electrolytes when used in larger volumes and for a longer time span.

Efficacy of Different Fluid Resuscitation Methods on Coagulation Function of Rats with Traumatic Hemorrhagic Shock

BACKGROUND

Fluid resuscitation is widely used for treating traumatic hemorrhagic shock. We focused on the efficacies of different fluid resuscitation methods on improving coagulation function of traumatic hemorrhagic shock (THS) rats.

MATERIALS AND METHODS

Sprague-Dawley rats (n = 100) were randomly divided into 5 groups, namely, Sham group, THS group, acetic acid Ringer's fluid (AR) group, hydroxyethyl starch solution (HES) group, and AR + HES group. A THS rat model was established by left femoral bleeding. The effects of different fluid resuscitation methods on conventional coagulation function parameters, Rotational thromboelastometry parameters, platelet-derived microparticles and endothelial cell-derived microparticles content of the THS rats were detected by ACL TOP system, rotation thromboelastometry, and flow cytometry, respectively.

RESULTS

Using AR and HES alone had no significant effect on the coagulation function of THS rats, but the two in combination reduced the increases of thrombin time, prothrombin time, activated part thrombin time, international normalized ratio, fibrin degradation products, D-dimer and the decreases of platelet count and fibrinogen concentration induced by THS. The CT and CFT were significantly reduced, whereas α and MCF were increased in the THS rats in AR + HES group. The combination of AR and HES reversed the effect of THS on elevating platelet-derived microparticles and endothelial cell-derived microparticle levels. In addition, the coagulation was relatively the optimal in the AR, HES, and AR + HES groups when the mice were resuscitated to a mean arterial pressure of 60 mmHg.

CONCLUSIONS

AR combined with HES has a significant protective effect on coagulation function of THS rats when the mean arterial pressure reaches 60 mmHg.

Modeling trauma in rats: similarities to humans and potential pitfalls to consider

Trauma is the leading cause of mortality in humans below the age of 40. Patients injured by accidents frequently suffer severe multiple trauma, which is life-threatening and leads to death in many cases. In multiply injured patients, thoracic trauma constitutes the third most common cause of mortality after abdominal injury and head trauma. Furthermore, 40-50% of all trauma-related deaths within the first 48 h after hospital admission result from uncontrolled hemorrhage. Physical trauma and hemorrhage are frequently associated with complex pathophysiological and immunological responses. To develop a greater understanding of the mechanisms of single and/or multiple trauma, reliable and reproducible animal models, fulfilling the ethical 3 R's criteria (Replacement, Reduction and Refinement), established by Russell and Burch in 'The Principles of Human Experimental Technique' (published 1959), are required. These should reflect both the complex pathophysiological and the immunological alterations induced by trauma, with the objective to translate the findings to the human situation, providing new clinical treatment approaches for patients affected by severe trauma. Small animal models are the most frequently used in trauma research. Rattus norvegicus was the first mammalian species domesticated for scientific research, dating back to 1830. To date, there exist numerous well-established procedures to mimic different forms of injury patterns in rats, animals that are uncomplicated in handling and housing. Nevertheless, there are some physiological and genetic differences between humans and rats, which should be carefully considered when rats are chosen as a model organism. The aim of this review is to illustrate the advantages as well as the disadvantages of rat models, which should be considered in trauma research when selecting an appropriate in vivo model. Being the most common and important models in trauma research, this review focuses on hemorrhagic shock, blunt chest trauma, bone fracture, skin and soft-tissue trauma, burns, traumatic brain injury and polytrauma.

Malate Protects the Kidneys From Hemorrhagic Shock-Induced Injury in an Experimental Rat Model

BACKGROUND

In the past, protective effects in terms of prolonged survival of malate-containing solutions were demonstrated in the treatment of experimental hemorrhagic shock (HS). The objective of the present study was to investigate malate's impact on the kidneys. Therefore, renal function and morphological and histological anomalies were examined.

MATERIALS AND METHODS

Male Wistar rats were subjected to severe HS by dropping the mean arterial blood pressure to 25-30 mmHg. The depth was held for 60 min. Subsequently, reperfusion with Ringer's solution or a 10 mM malate-containing solution was performed both together with blood in a 2:1 relation, followed by an observation period of 150 min.

RESULTS

Compared with the control group (Ringer's solution), malate increased diuresis and, thus, enhanced excretion of creatinine and urea. Shock-induced histopathological changes were reduced by malate administration. Renal hemorrhages in the straight proximal tubule and in the distal tubule were reduced and even significantly reduced in the proximal convoluted tubule. Malate significantly preserved the endothelial glycocalyx in the proximal tubule. Surprisingly, malate induced glucosuria in the absence of a significant renal dysfunction, morphological damage, or hyperglycemia.

CONCLUSIONS

The protective effect of malate observed in the treatment of severe HS in the rat may be explained by a certain protective effect of this substance for the kidney.

Pyruvate as a novel carrier of hydroxyethyl starch 130/0.4 may protect kidney in rats subjected to severe burns

BACKGROUND

The carrier of hydroxyethyl starch (HES) may play a critical role in kidney injury in fluid resuscitation. This study aimed mainly to compare effects of pyruvate-enriched saline with normal saline (NS) and acetate Ringer's (AR) solution as a carrier in HES130/0.4 on kidney function in rats subjected to severe burns.

METHODS

Using a lethal burn model, 140 rats were randomly allocated in seven groups (n = 20): sham group (group S); no fluid after burn (group N); burn resuscitated with NS (group NS); burn resuscitated with pyruvate saline (group PS); burn resuscitated with AR plus pyruvate-HES (group SP); burn resuscitated with AR plus acetate-HES (group SA), and burn resuscitated with AR plus NS-HES (group SN). A low volume (18.75 mL·kg^-1 during 12 h) of HES130/0.4 was infused with the ratio of 1:1 to crystalloids. Renal surface blood flow, blood creatinine and blood urea nitrogen, early sensitive indicators of kidney function: alpha-1 microglobulin, cystatin-C, and neutrophil gelatinase-associated lipocalin in blood and urine, and kidney tissue water contents were determined. Renal histopathological alterations with Paller scores were also measured at 8 h and 24 h after burn (n = 10), respectively.

RESULTS

The results showed in a comparable manner that group SP was the best in three HES groups and group PS was superior to group NS in renal preservation; group SP appeared significantly beneficial compared with group PS in renal surface blood flow, cystatin-C, neutrophil gelatinase-associated lipocalin, water contents, and Paller scores at 8-h or both time points after burn, respectively (all P < 0.05).

CONCLUSIONS

The carrier of HES130/0.4 played a crucial role in kidney injury in fluid resuscitation of rats subjected to severe burns. Pyruvate-enriched HES130/0.4 was superior and HES130/0.4, per se, might be not renocytotoxic, but renoprotective. Further studies are warranted.

Tranexamic acid prolongs survival after controlled hemorrhage in rats

BACKGROUND

The plasmin/plasminogen inhibitor tranexamic acid (TXA) is mainly used in elective surgeries with a higher blood loss to avoid uncontrolled bleeding. Recently, TXA has also been shown to reduce mortality in trauma patients. It is assumed that its beneficial effects are principally caused by its antifibrinolytic properties. We hypothesize that TXA also improves survival in a modified Wigger's model of hemorrhagic shock by a mechanism other than antifibrinolysis.

MATERIALS AND METHODS

Male Wistar rats were intermittently bled until the mean arterial blood pressure was dropped to 25-30 mm Hg (severe shock). After shock induction, the animals received either 0.14-0.15 mL TXA (30 mg/kg) i.v. or the equivalent volume of 0.9% NaCl given as bolus. Adjacent to the shock period, the rats were resuscitated with Ringer's solution within 30 min and observed for another 150 min unless the animals died earlier.

RESULTS

In the animals treated with TXA, survival was clearly prolonged and acid-base parameters showed some differences as compared to the animals receiving only NaCl. In the model used, coagulation slightly declined, but an increased fibrinolysis was not observed.

CONCLUSIONS

Since in the applied shock model fibrinolysis is negligible, we postulate that TXA is capable of providing protection against hemorrhagic shock independent from its antifibrinolytic properties.

L-Malate's Plasma and Excretion Profile in the Treatment of Moderate and Severe Hemorrhagic Shock in Rats

Introduction. Malate is a standard component in fluid therapy within a wide range of medical applications. To date, there are insufficient data regarding its plasma distribution, renal excretion, and metabolism after infusion. This study aimed to investigate these three aspects in a rat model of moderate and severe hemorrhagic shock (HS). Methods. Male Wistar rats were subjected to HS by dropping the mean arterial blood pressure to 25-30 mmHg (severe) and 40-45 mmHg (moderate), respectively, for 60 minutes. Subsequently, reperfusion with Ringer-saline or a malate containing crystalloid solution (7 mM, 13.6 mM, and 21 mM, resp.) was performed within 30 minutes, followed by an observation period of 150 minutes. Results. In the present experiments, malate rapidly disappeared from the blood, while only 5% of the infused malate was renally excreted. In the resuscitation interval the urinary citrate and succinate amounts significantly increased compared to control. Conclusion. Malate's half-life is between 30 and 60 minutes in both, moderate and severe HS. Thus, even under traumatic conditions malate seems to be subjected to rapid metabolism with participation of the kidneys.