Chronic resuscitation after trauma-hemorrhage and acute fluid replacement improves hepatocellular function and cardiac output

Trauma care in Germany: an inclusive system

BACKGROUND

Development of trauma systems is a demanding process. The United States and Germany both have sophisticated trauma systems. This manuscript is a summary of political, economic, and medical changes that have led to the development of both trauma systems and the current high-quality standards.

QUESTIONS/PURPOSES

We specifically asked three questions: (1) What tasks are involved in developing a modern trauma system? (2) What is the approach to achieve this task? (3) Do these systems work?

METHODS

We conducted a systematic review of relevant articles by searching electronic databases (PubMed, Embase, Cochrane library) using the following search terms: "trauma system", "polytrauma", "trauma networks", and "trauma registry". Of 2573 retrieved manuscripts, the authors made a personal selection of studies. A personal study selection from our experiences was added when their contribution to the topic was judged important.

RESULTS

Worldwide, similar tasks concerning trauma care have to be addressed. In most societies, traffic accidents and firearm-related injuries contribute to a high number of trauma victims. The German approach has been to decrease the number of accidents through injury prevention and to provide better care by establishing an emergency medical system. For in-hospital treatment, clinical care has constantly improved and a close interaction with members from the American Association for the Surgery of Trauma and the Orthopaedic Trauma Association has helped a great deal to achieve these improvements. The German healthcare system was developed as a powerful healthcare tool covering patients from injury to rehabilitation. In addition, trauma and injury research has been strengthened to deal with various questions of trauma care.

CONCLUSIONS

Organized injury prevention programs and systematized professional patient care can address the issues associated with the global burden of trauma. These trauma systems require constant monitoring and improvement.

Systemic microcirculation after complete high and low thoracic spinal cord section in rats

Spinal cord injury (SCI) produces multiple systemic and metabolic alterations. Although some systemic alterations could be associated with ischemic organ damage, little is known about microvascular blood flow (MVBF) in organs other than the spinal cord after acute SCI. We used laser Doppler flowmetry in anesthetized rats to assess MVBF in several tissues before and after complete T-2 and T-9 SCI at 1 h and on days 1, 3, and 7 post-SCI. Mean arterial blood pressure (MAP), heart rate and hematologic variables also were recorded. MAP changes after T-2 injury were not significant, while MAP decreased significantly 1 h after T-9 injury. Statistically significant bradycardia occurred after T-2 injury at 7 days; statistically significant tachycardia occurred after T-9 injury at 1, 3, and 7 days. Hematocrit significantly increased at day 1 and decreased at days 3 and 7 after T-2 injury. SCI was associated with significant decreases in MVBF in liver, spleen, muscle and fore footpad skin. Changes in MVBF in hind footpad skin and kidney were not significant. Changes were more pronounced at 1 h and 1 day post-SCI. Significant differences between MVBF after T-2 and T-9 SCI occurred only in liver. MVBF significantly correlated with regional peripheral vascular resistances (assessed using the MAP/MVBF ratio), but not with MAP. In conclusion, organ-specific changes in systemic MVBF that are influenced by the level of SCI, could contribute to organ dysfunction.

Mechanism of cardiac depression after trauma-hemorrhage: increased cardiomyocyte IL-6 and effect of sex steroids on IL-6 regulation and cardiac function

A prolonged depression of cardiovascular function occurs in males after trauma-hemorrhagic shock (T-H). Although a correlation between increased circulatory IL-6 levels and poor outcome has been reported after T-H, it remains unknown whether T-H increases IL-6 levels locally in cardiomyocytes and whether there is a correlation between altered cardiac function and local IL-6 production after T-H. T-H was induced in normal, castrated (2 wk before T-H), and 17beta-estradiol (E2)-treated (0.5 mg sc, 1 wk before T-H) adult male rats. At 2 h after T-H or sham operation, cardiac output, heart rate, mean arterial pressure, positive and negative first derivative of pressure (+/-dP/dt), stroke volume, and total peripheral resistance were determined. Cardiomyocytes were isolated and divided into two parts: one was used for measurements of intracellular IL-6 levels using fluorescein-activated cell sorting, and the other was used to isolate RNA to determine IL-6 gene expression by quantitative real-time PCR. In addition, cardiac IL-6 protein levels were measured in freshly isolated hearts by Western blotting. Cardiac output, stroke volume, +dP/dt, -dP/dt, and total peripheral resistance were markedly altered after T-H. These parameters, except -dP/dt, improved significantly in the castrated group; however, all these parameters were restored in E2-treated males. Cardiomyocyte IL-6 mRNA expression and intracellular IL-6 production increased after T-H. Cardiac IL-6 protein levels increased after T-H in freshly isolated heart. Castration and E2 treatment attenuated cardiomyocyte intracellular IL-6 levels and cardiac IL-6 protein levels after T-H; however, only E2 treatment attenuated cardiomyocyte IL-6 gene expression. Thus there is an inverse correlation between cardiomyocyte IL-6 levels and cardiac function after T-H. The salutary effects of E2 on cardiac function after T-H may be due in part to decreased IL-6 synthesis in cardiomyocytes.

Differential fluid regulation during and after soft tissue trauma and hemorrhagic shock in males and proestrus females

Gender differences in immune and organ functions have been described in different rodent models of trauma- and pressure-controlled hemorrhagic shock. We hypothesized that gender influences the regulation of plasma and tissue fluids in rats under such conditions. To study this we used male and weight matched proestrus female Sprague-Dawley rats, which were assigned to three groups (n = 7/group): sham, maximal bleedout (trauma and 45 min of blood pressure at 35 mmHg without resuscitation), or 5 h after completion of trauma-hemorrhage and resuscitation. Trauma-hemorrhage involved midline laparotomy and approx. 90 min of hemorrhagic shock (35 mmHg), followed by fluid resuscitation (4x the shed blood volume with Ringers lactate). (51)Cr-EDTA, (125)I-albumin distribution, and wet weight/dry weight were used to calculate plasma volume and extracellular fluid volume and cellular water content. Proestrus female rats showed significantly higher plasma volumes compared with weight-matched males. The volume of blood withdrawn in the first 15 min of hemorrhagic shock was significantly less in proestrus females compared with males; however, there was no significant difference in the total shed blood volume. Moreover, proestrus females showed less interstitial edema formation compared with male rats at 5 h after resuscitation. We conclude that differences in the regulation of plasma and tissue volumes exist between males and proestrus females during and after trauma-hemorrhage. The increased circulating blood volume could contribute the improved immune and organ functions in proestrus females under those conditions.

Pyruvate improves redox status and decreases indicators of hepatic apoptosis during hemorrhagic shock in swine

Previous studies have shown that the liver is the first organ to display signs of injury during hemorrhagic shock. We examined the mechanism by which pyruvate can prevent liver damage during hemorrhagic shock in swine anesthetized with halothane. Thirty minutes after the induction of a 240-min controlled arterial hemorrhage targeted at 40 mmHg, hypertonic sodium pyruvate (0.5 g. kg(-1). h(-1)) was infused to achieve an arterial concentration of 5 mM. The volume and osmolality effects of pyruvate were matched with 10% saline (HTS) and 0.9% saline (NS). Although the peak hemorrhage volume increased significantly in both the pyruvate and HTS group, only the pyruvate treatment was effective in delaying cardiovascular decompensation. In addition, pyruvate effectively maintained the NADH/NAD redox state, as evidenced by increased microdialysate pyruvate levels and a significantly lower lactate-to-pyruvate ratio. Pyruvate also prevented the loss of intracellular antioxidants (GSH) and a reduction in the GSH-to-GSSG ratio. These beneficial effects on the redox environment decreased hepatic cellular death by apoptosis. Pyruvate significantly increased the ratio of Bcl-Xl (antiapoptotic molecule)/Bax (proapoptotic molecule), prevented the release of cytochrome c from mitochondria, and decreased the fragmentation of caspase 3 and poly(ADP ribose) polymerase (DNA repair enzyme). These beneficial findings indicate that pyruvate infused 30 min after the onset of severe hemorrhagic shock is effective in maintaining the redox environment, preventing the loss of the key antioxidant GSH, and decreasing early apoptosis indicators.

Continuous resuscitation after hemorrhage and acute fluid replacement improves cardiovascular responses

BACKGROUND

Although acute fluid replacement after trauma and severe hemorrhage remains the cornerstone in the management of trauma victims, it remains unknown whether continuous resuscitation after trauma-hemorrhage and acute fluid replacement produces salutary effects on cardiovascular function and reduces proinflammatory cytokine release.

METHODS

Adult male rats underwent laparotomy (ie, soft tissue trauma) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the shed blood volume was returned in the form of Ringer's lactate (RL). The animals were then resuscitated with 4 times the volume of shed blood with RL for 60 minutes, followed by continuous resuscitation with RL at 5 mL/h/kg for 48 hours after the acute fluid replacement. At 48 hours after hemorrhage, mean arterial pressure, cardiac output, and left ventricular contractility parameters, such as the maximal rates of ventricular pressure increase (+dP/dt(max)) and decrease (-dP/dt(max)), were determined. Microvascular blood flow in the intestine and kidney was assessed by laser Doppler flowmetry. In addition, plasma levels of TNF-alpha were assayed by enzyme-linked immunosorbent assay.

RESULTS

The mean arterial pressure and cardiac output were decreased by 34% and 18%, respectively, at 48 hours after hemorrhage and acute resuscitation. Continuous resuscitation, however, markedly improved these parameters. Similarly, +dP/dt(max) and -dP/dt(max) decreased significantly after hemorrhage and acute fluid replacement but was restored to sham values after continuous resuscitation. Microvascular blood flow in the gut and kidneys was decreased after hemorrhage and acute resuscitation by 34% and 35%, respectively. However, intestinal and renal perfusion was maintained at the sham levels at 48 hours after continuous resuscitation. In addition, the upregulated TNF-alpha after acute resuscitation alone was reduced after continuous resuscitation.

CONCLUSIONS

Continuous resuscitation after acute fluid replacement appears to be a useful approach for restoring and maintaining cardiovascular function and organ perfusion after trauma and severe hemorrhage.

Estradiol administration after trauma-hemorrhage improves cardiovascular and hepatocellular functions in male animals

OBJECTIVE

To determine whether female sex steroids have any salutary effects on the depressed cardiovascular and hepatocellular functions following trauma and hemorrhage in male animals.

SUMMARY BACKGROUND DATA

Studies indicate that gender difference exists in the immune and cardiovascular responses to trauma-hemorrhage, and that male sex steroids appear to be responsible for producing immune and organ dysfunction, but it remains unknown if female sex steroids produce any salutary effects on the depressed cellular and organ functions in males following trauma and hemorrhage.

METHOD

Adult male Sprague-Dawley rats underwent a midline laparotomy (i.e., trauma induction), and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of the maximum bleed-out volume was returned in the form of Ringer's lactate (RL). Animals were then resuscitated with RL at 4 times the shed blood over 60 minutes. 17beta-estradiol (50 microg/kg) or an equal volume of vehicle was injected subcutaneously 15 minutes before the end of resuscitation. The maximal rate of ventricular pressure increase or decrease (+/-dP/dtmax), cardiac output, and hepatocellular function (i.e., maximal velocity and overall efficiency of in vivo indocyanine green clearance) were assessed at 24 hours after hemorrhage and resuscitation. Plasma levels of interleukin (IL)-6 were also measured.

RESULTS

Left ventricular performance, cardiac output, and hepatocellular function decreased significantly at 24 hours after trauma-hemorrhage and resuscitation. Plasma levels of IL-6 were elevated. Administration of 17beta-estradiol significantly improved cardiac performance, cardiac output, and hepatocellular function, and attenuated the increase in plasma IL-6 levels.

CONCLUSION

Administration of estrogen appears to be a useful adjunct for restoring cardiovascular and hepatocellular functions after trauma-hemorrhage in male rats.

Alterations in tissue oxygen consumption and extraction after trauma and hemorrhagic shock

OBJECTIVES

Although trauma and hemorrhage are associated with tissue hypoperfusion and hypoxemia, changes in oxygen delivery (DO2), oxygen consumption VO2), and oxygen extraction at the organ level in a small animal (such as the rat) model of trauma and hemorrhage have not been examined. Therefore, the objectives of this study were to determine whether blood flow, DO2, VO2, and oxygen extraction ratio in various organs are differentially altered after trauma-hemorrhagic shock and acute resuscitation in the rat.

DESIGN

Prospective, randomized animal study.

SETTING

A university research laboratory.

SUBJECTS

Male Sprague-Dawley rats (n = 6-7 animals/group) weighing 275-325 g.

INTERVENTIONS

Male rats underwent laparotomy (i.e., soft tissue trauma) and were bled to and maintained at a blood pressure of 40 mm Hg until 40% of shed blood volume was returned in the form of lactated Ringer's solution. They were then resuscitated with four times the volume of shed blood with lactated Ringer's solution for 60 mins. At 1.5 hrs postresuscitation, cardiac output and blood flow were determined by using strontium-85 microspheres. Blood samples (0.15 mL each) were collected from the femoral artery and vein and the hepatic, portal, and renal veins to determine total hemoglobin and oxygen content. Systemic and regional DO2, VO2, and oxygen extraction ratio were then calculated.

MEASUREMENTS AND MAIN RESULTS

Both the systemic hemoglobin and systemic arterial oxygen content in hemorrhaged animals at 1.5 hrs postresuscitation were >50% lower as compared with sham-operated controls. Cardiac output and blood flow in the liver, small intestine, and kidneys decreased significantly, but blood flow in the brain and heart remained unaltered after hemorrhage and resuscitation. Systemic DO2 and VO2 were 73% and 54% lower, respectively, than controls at 1.5 hrs after resuscitation. Similarly, regional DO2 and VO2 in the liver, small intestine, and kidneys decreased significantly under such conditions. In addition, the liver had the most severe reduction in VO2 (76%) among the tested organs. However, the oxygen extraction ratio in the liver of sham animals was the highest (72%) and remained unchanged after hemorrhage and resuscitation.

CONCLUSION

Because the liver experienced the most severe reduction in VO2 associated with an unchanged oxygen extraction capacity, this organ appears to be more vulnerable to hypoxic insult after hemorrhagic shock.

Do different rates of fluid resuscitation adversely or beneficially influence immune responses after trauma-hemorrhage?

BACKGROUND

Although rapid fluid resuscitation continues to be an important component of the initial therapy for trauma patients, it remains unknown whether the rate of fluid administration after trauma-hemorrhage has any deleterious or beneficial effects on immunity.

METHODS

Male C3H/HeN mice were subjected to sham operation or soft-tissue trauma (midline laparotomy) and hemorrhagic shock (mean arterial blood pressure of 35+/-5 mm Hg for 90 minutes) followed by resuscitation with four times the volume of shed blood in the form of lactated Ringer's solution over 30 minutes (rapid rate), 60 minutes (moderate rate), or 120 minutes (slow rate). The animals were killed at either 4 hours or 4 days after the end of trauma-hemorrhage. Spleens were harvested and splenocyte interleukin (IL)-3 and interferon-gamma (IFN-gamma) release as well as splenic macrophage IL-1beta and IL-6 release were determined.

RESULTS

The results indicate that at 4 hours after trauma-hemorrhage, splenocyte IL-3 and IFN-gamma release were significantly depressed in all animals subjected to trauma-hemorrhage compared with sham-operated animals. At 4 days after trauma-hemorrhage, splenocyte IL-3 and IFN-gamma release were restored in mice resuscitated with the slow rate of resuscitation; however, the release of these cytokines remained significantly depressed in animals resuscitated with the moderate or rapid rates. Splenic macrophage IL-1beta and IL-6 release were significantly depressed at 4 hours after trauma-hemorrhage. At 4 days after trauma-hemorrhage, the release of these proinflammatory cytokines was still depressed in animals resuscitated with the rapid rate. In contrast, splenic macrophage IL-1beta and IL-6 release were restored in mice receiving the slow rate of resuscitation.

CONCLUSION

These results suggest that a slower rate of fluid resuscitation after trauma-hemorrhage leads to a faster restoration of the depressed cell-mediated immunity, whereas rapid fluid resuscitation produces a prolonged depression of immune responses. In view of this, we propose that a prospective clinical study of this type must be performed in a select group of trauma patients to determine whether or not a slower rate of fluid resuscitation also improves immune responses in trauma patients.

Testosterone: the crucial hormone responsible for depressing myocardial function in males after trauma-hemorrhage

OBJECTIVE

To determine whether testosterone depletion in males before trauma-hemorrhage has any salutary effects on cardiac performance after hemorrhage and resuscitation.

SUMMARY BACKGROUND DATA

Studies indicate that castration of male mice before trauma-hemorrhage prevents the immunodepression seen after hemorrhage and resuscitation. However, the effect of precastration on cardiac performance under such conditions remains unknown.

METHODS

Male rats were castrated or sham-castrated 14 days before the experiment. After laparotomy (i.e., induction of trauma), the rats were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximal shed volume was returned in the form of Ringer's lactate solution. The animals were then resuscitated with four times the shed blood volume with Ringer's lactate solution over 60 minutes. Heart performance was measured using a left ventricular catheter connected to an in vivo heart performance analyzer. Indices of left ventricular performance (i.e., maximal rate of the pressure increase [+dP/dt(max)] and decrease [-dP/dt(max)) were measured up to 4 hours after trauma, hemorrhagic shock, and resuscitation.

RESULTS

In sham-castrated animals, trauma-hemorrhage and resuscitation decreased the in vivo heart performance as evidenced by the reduced values of +dP/dt(max) and -dP/dt(max). Precastrated animals, however, showed significantly higher values of +dP/dt(max) and -dP/dt(max) than sham-castrated animals after trauma-hemorrhage and resuscitation.

CONCLUSIONS

Testosterone antagonism in males might be an effective approach for maintaining myocardial function after adverse circulatory conditions. Although testosterone depletion in male trauma victims is neither practical nor advocated, testosterone receptor blockade after trauma may represent a novel and useful adjunct for maintaining normal myocardial performance under those conditions.