In preclinical treatment of polytraumatized patients crystalloids are preferentially used. To avoid metabolic acidosis, metabolizable anions like lactate or acetate are used to replace chloride in these solutions. We here studied the effects of malated Ringer’s in resuscitation of both shock severities in comparison to lactated and acetated Ringer’s. Male Wistar rats underwent severe (mean arterial blood pressure (MAP) of 25–30 mmHg) or moderate (MAP 40–45 mmHg) hemorrhagic shock. Adjacent to the shock period animals were resuscitated with acetated (AR), lactated (LR), or malated Ringer’s (MR) and observed for 150 min. MR improved survival compared with LR and AR in severe hemorrhagic shock whereas it was equally effective to LR and superior to AR in moderate hemorrhagic shock. In all other parameters tested, MR was also effective similar to the other solutions under these conditions. We conclude that MR is preferable to AR and LR in resuscitation of hemorrhagic shock independent of shock depth. The positive effects of MR may stem from the absence of any adverse impact on energy metabolism under both conditions.
Beside craniocerebral injury, hemorrhagic shock is one of the main causes of death among trauma patients [
During the metabolism of lactate, acetate, and malate, H+ ions are consumed (or HC
In order to replace lactate, acetate can be used as metabolizable anion [
Normal saline and AR were from B. Braun (Melsungen, Germany) and MR, Ringer’s solution (RS), and LR (only containing l-lactate) from Fresenius (Bad Homburg, Germany). Ketamine 10% was from Ceva (Düsseldorf, Germany), lidocaine (Xylocaine 1%) from AstraZeneca (Wedel, Germany), and acid citrate dextrose A solution from Baxter (Deerfield, IL). Portex catheters (inner diameter: 0.58 mm, outer diameter: 0.96 mm; Smiths Medical International, Hythe, UK) and medical oxygen (Air Liquide, Düsseldorf, Germany) were obtained from the vendors listed.
Male Wistar rats (400–500 g) were obtained from the central animal unit of the Essen University Hospital. Animals were kept under standardized conditions of temperature (22°C ± 1°C), humidity (
Anesthesia, analgesia, catheter insertions, shock induction, resuscitation schedule, and blood sampling, were basically performed as described previously with slight modifications [
After insertion of the catheter, animals were allowed to adapt for 20 min before hemorrhagic shock was induced by removing 1-2 mL blood every 3 min through the femoral artery catheter using 2-mL syringes (Terumo, Leuven, Belgium). Bleeding was continued until the mean arterial blood pressure (MAP) dropped either to 25–30 mmHg for severe shock or to 40–45 mmHg for moderate shock, which typically took about 20 min in both groups. During the following 10 min, the MAP was fine-tuned by sampling of smaller blood volumes (0.5–1 mL). For the next 60 min, the MAP was kept between 25–30 mmHg and 40–45 mmHg, respectively, typically without the need of any further intervention. In some individual cases small blood samples had to be withdrawn or administered to keep the MAP in the desired range. The blood used for adjustment was collected during shock induction in syringes containing acid dextrose A solution (ACD-A). After the shock phase, study group-specific resuscitation fluids were infused into the femoral vein within 30 min using a syringe pump (Perfusor-Secura FT; B. Braun, Melsungen, Germany). Experiments were continued for another 150 min, unless the animals died earlier. To compensate for fluid loss over surgical areas and the respiratory epithelium, RS (5 mL/kg/h) was infused through the femoral vein catheter throughout the experiment.
All 46 animals were randomly assigned to the following groups: sham group (no shock, no resuscitation, six animals), moderate shock/AR group (shock, resuscitation with acetated Ringer’s equal to three times the shed blood volume, eight animals), moderate shock/LR group (shock, resuscitation with lactated Ringer’s equal to three times the shed blood volume, eight animals), moderate shock/MR group (shock, resuscitation with malated Ringer’s equal to three times the shed blood volume, eight animals), severe shock/AR group (shock, resuscitation with acetated Ringer’s equal to three times the shed blood volume, eight animals), severe shock/LR group (shock, resuscitation with lactated Ringer’s equal to three times the shed blood volume, eight animals), severe shock/MR group (shock, resuscitation with malated Ringer’s equal to three times the shed blood volume, eight animals).
The volume of fluid to be used for resuscitation is based on the well established 3 : 1 rule [
Systolic blood pressure, diastolic blood pressure, and MAP were recorded continuously via the femoral artery catheter that was connected to a pressure transducer and displayed on a monitor. Heart rates were determined from systolic blood pressure spikes. The core body temperature of the rats was kept at
Using a 2-mL syringes containing 80 IU electrolyte-balanced heparin (Pico50; Radiometer Medical, Brønshøj, Denmark), blood samples (0.5–0.7 mL) for blood gas analysis and the assessment of marker enzymes activities were taken from the femoral artery immediately after its insertion (
Experiments were performed with eight animals per experimental group, except for the sham group, which consisted of six animals. Data are expressed as mean values ± SEM. Outliers were removed after box-plot analysis. Comparisons among multiple groups were performed using one-way analysis of variance (ANOVA) either for nonrecurring or for repeated measures followed by Fisher (LSD, least significant difference) post hoc analysis. Survival curves were generated according to the Kaplan-Meier method and were compared with the log-rank test.
All animals of the sham group survived the experiment (data not shown). In the severe shock groups, the animals receiving LR were the first who died (beginning at
Effects of lactated, acetated, and malated Ringer’s on survival in severely/moderately shocked rats. Rats underwent severe and moderate hemorrhage and then were resuscitated with either lactated Ringer’s (LR), acetated Ringer’s (AR), or malated Ringer’s solution (MR). The survival per group is shown as Kaplan-Meier plot (
In the moderate shock/MR and LR group, only one animal died during the experiment (at
In the sham group animals the mean arterial blood pressure (MAP) remained fairly constant at 100 mmHg throughout the experiment (data not shown). In the animals of the shock groups, the MAP was decreased either to 25–30 mmHg (severe shock) or to 40–45 mmHg (moderate shock) within 30 min and subsequently maintained in these ranges for 60 min (Figure
Effects of lactated, acetated, and malated Ringer’s on MAP in severely/moderately shocked rats. Rats underwent moderate and severe hemorrhage (shock induction: dark grey; shock phase: light grey) and then were resuscitated (dark grey) with either lactated Ringer’s (LR), acetated Ringer’s (AR), or malated Ringer’s solution (MR) and observed for further 150 min or until the first animal of the respective group died. (a) Mean arterial blood pressure (MAP) in moderate hemorrhagic shock of LR, AR, and MR and (b) MAP in severe hemorrhagic shock of LR, AR, and MR treated animals. Shown are mean values ± SEM (
In the sham group animals, no significant changes in hematocrit and plasma electrolyte concentrations were observed (data not shown). In all shock groups, independent of shock depth, there were no alterations in the Na+ and Ca2+ concentrations, but slight elevations in the Cl− and K+ concentrations during the postresuscitation phase. In contrast to the moderate shock groups where the hematocrit remained stable during the postresuscitation phase, in the severe shock groups it slightly increased after resuscitation.
The pH, BE, and pCO2 of the sham group were stable at values of 7.35, −3 mmol/L, and 45 mmHg, respectively, throughout the experiment (data not shown). During shock induction, the shock and the resuscitation phase, the pH decreased to values around 7.1 in the severe shock group animals, but remained around 7.35 in the moderate shock groups (Figure
Effects of lactated, acetated, and malated Ringer’s on the acid-base balance in severely/moderately shocked rats. Rats underwent severe and moderate hemorrhage (shock induction: dark grey; shock phase: light grey) and then were resuscitated (dark grey) with either lactated Ringer’s (LR), acetated Ringer’s (AR), or malated Ringer’s solution (MR) and observed for further 150 min or until the first animal of the respective group died. (a) Blood pH, (b) base excess, (c) CO2 partial pressure (pCO2), and (d) O2 partial pressure (pO2). Values are means ± SEM (
Sham group plasma lactate and glucose concentration remained stable at around 1 mmol/L and 200 mg/dL, respectively, during the whole experiment (data not shown). In the severe shock groups, the plasma lactate concentration increased to about 8 mmol/L during shock induction and the shock phase. During resuscitation and the postresuscitation phase it either remained at this level (severe shock/LR group) or declined to about 5 (severe shock/AR group) and 3 mmol/L (severe shock/MR group), respectively. In all moderate shock groups, the plasma lactate concentration rose to 2 to 3 mmol/L during shock induction and the shock phase but subsequently decreased to about 2 mmol/L (Figure
Effects of lactated, acetated, and malated Ringer’s on lactate and glucose concentration in severely/moderately shocked rats. Rats underwent severe and moderate hemorrhage (shock induction: dark grey; shock phase: light grey) and then were resuscitated (dark grey) with either lactated Ringer’s (LR), acetated Ringer’s (AR), or malated Ringer’s solution (MR) and observed for further 150 min or until the first animal of the respective group died. Blood glucose (a) and lactate concentrations (b). Values are means ± SEM (
In the sham group, plasma GOT, GPT, LDH and CK activities did not exceed 80 U/L, 60 U/L, 160 U/L, and 350 U/L, respectively, throughout the whole experiment (data not shown), in order to match the figure. Plasma enzyme activities began to rise upon resuscitation and in the postresuscitation phase without any differences within the groups of one shock depth (Figure
Effects of lactated, acetated, and malated Ringer’s on plasma enzyme activities in severely/moderately shocked rats. Rats underwent severe and moderate hemorrhage (shock induction: dark grey; shock phase: light grey) and then were resuscitated (dark grey) with either lactated Ringer’s (LR), acetated Ringer’s (AR), or malated Ringer’s solution (MR) and observed for further 150 min or until the first animal of the respective group died. GOT activity (a), GPT activity (b), LDH activity (c), and CK activity (d). Values are means ± SEM (
At present, the most frequently applied metabolizable anion in crystalloid solutions is lactate. LR was shown to be effective in the treatment of metabolic disorders in children [
For acetate supplied in saline solutions, mainly beneficial effects have been described, such as a positive influence on the acid-base balance in and after hemorrhagic shock, presumably resulting from its fast and ubiquitous catabolic degradation [
Although the metabolism of malate and its effects on metabolic acidosis and the cardiovascular system under hypoxic conditions have been extensively studied [
The present study indicates that the successful application of LR and AR in the treatment of hemorrhagic shock is dependent on shock severity. While LR provided almost optimal results in moderate hemorrhagic shock, AR seems more advantageous in severe hemorrhagic shock. Independent of shock severity, however, MR appears to be the superior resuscitation solution. In moderate hemorrhagic shock it provided results comparable to LR and in severe hemorrhagic shock outcome was clearly improved as compared to both other solutions. Thus, the use of MR, especially in preclinical resuscitation schedules in which the magnitude of shock can only be estimated, should be preferred. However, the results presented here apply only for the experimental conditions used here, that is, severe and moderate hemorrhagic shock with a controlled blood loss but without further attempts at treatment. Whether they can be adopted to the treatment of polytraumatized patients remains to be elucidated.
Acid citrate dextrose-A
Analysis of variance
Acetated Ringer’s
Base excess
Beats per min
Creatine kinase
Glutamate-oxaloacetate transaminase
Glutamate-pyruvate transaminase
Hematocrit
Lactate dehydrogenase
Lactated Ringer’s
Mean arterial blood pressure
Malated Ringer’s
Carbon dioxide partial pressure
Oxygen partial pressure.
The address of Judith Keitel, Bjoern Hussmann, and Sven Lendemans was University Hospital Essen, Essen, Germany, when the data was collected; however, the current address is Alfried Krupp Hospital, Essen, Germany.
The authors declare that there is no conflict of interests regarding the publication of this paper.