Small volume hypertonic hydroxyethyl starch reduces acute microvascular dysfunction after closed soft-tissue trauma

[Intramedullary nailing vs. locking plate osteosynthesis in proximal humeral fractures: Long-term outcome]

BACKGROUND

For the treatment of proximal humeral fractures two major therapeutic principles can be employed: intramedullary nailing (PHN) or locking plate osteosynthesis. The aim of this study was to evaluate and compare clinical and radiological long-term outcome of proximal humeral fracture stabilization using PHN or angular stable plating.

MATERIALS AND METHODS

In a retrospective study between March 2009 and March 2010, we analyzed 72 out of 118 patients with unified proximal humeral fracture who had been treated at least 3 years previously using PHN (44 patients) or angular stable plating (28 patients) in a level 1 trauma center. Functional and radiological outcomes were assessed at least 3 years after trauma using the Constant and Murley score and SF-36 score.

RESULTS

According to the Neer classification, there were 31 3-part fractures (PHN: 23; plate: 8) and 41 4-part fractures (PHN: 21; plate: 20), respectively. No clinical symptoms after 3 years were observed in 42 patients, whereas in 30 patients clinical symptoms were evaluated related to pain and/or loss of function. Functional outcome using the Constant and Murley score demonstrated a total score of 73 points (ipsilateral side) vs. 88 points (contralateral side) in all evaluated patients, on average.

CONCLUSION

Both PHN and angular stable plating are adequate treatment options for proximal humeral fractures. Both systems require precise preoperative planning and advanced surgical experience. No significant differences in long-term clinical and radiological outcome between implants regarding fracture classification, age of patient, and choice of implant were found.

[Treatment of proximal humeral fractures in Germany: Influence of the level of hospital care and the frequency of treatment]

BACKGROUND

Various treatment options exist for displaced proximal humeral fractures. The impact of the level of hospital care and frequency of treatment on current treatment regimens in Germany was analyzed.

MATERIAL AND METHODS

A total of 576 hospitals were included. The survey covered questions on frequency, diagnostics, classification, therapy, complications, and clinical scenarios.

RESULTS

In all, 48% of the hospitals returned the questionnaire: 73% treat more than 60% of the fractures surgically, mainly with angle-stable implants. The angle-stable plate is the treatment of choice for young patients, but older patients are treated using other treatment options. Problems and complications included malreduction, secondary displacement, screw perforation, avascular necrosis, and impingement. According to treatment indication, implant choice, and common complications, no significant differences between the level of hospital care and frequency of treatment were observed.

CONCLUSION

Independent of the level of hospital care and frequency of treatment, there is a trend for head-preserving angular-stable surgery with a homogenous level of treatment in Germany.

[Arthroscopic fracture management in proximal humeral fractures]

Arthroscopy has become increasingly more established in the treatment of proximal humeral fractures. In addition to the known advantages of minimally invasive surgery fracture and implant positioning can be optimized and controlled arthroscopically and relevant intra-articular concomitant pathologies (e.g. biceps tendon complex and rotator cuff) can be diagnosed and treated. Arthroscopic techniques have proven to be advantageous in the treatment of various entities of greater tuberosity fractures, lesser tuberosity fractures (suture bridging technique) and subcapital humeral fractures (arthroscopic nailing). This article presents an overview on innovative arthroscopic modalities for treating proximal humeral fractures, describes the surgical techniques and the advantages compared to open procedures as well as initial clinical results.

Early fluid resuscitation with hypertonic solution in a rat crush injury model

AIM OF THE STUDY

The aim of the study was to evaluate the effects of bolus infusion of hypertonic hydroxyethyl starches (HHESs) and continuous infusion of hypertonic saline (HTS) in the early resuscitation in crush syndrome.

METHODS

A rat model of crush injury was established. Rats were randomly divided into five groups: (1) HHES group, (2) HTS group, (3) volume resuscitation group, (4) normal resuscitation (NR) group, and (5) sham group. Blood samples were collected 6 h after the crush period for biochemical evaluation. Blood pressure was monitored throughout this experiment. Muscles and kidneys were evaluated morphologically 24 h after reperfusion. Twenty rats in each group were taken for survival observation for 72 h.

RESULTS

Compared with the NR and HTS groups, the HHES group had significantly increased the survival rate 72 h after release (P < 0.05). In the first 2 h after release, mean arterial blood pressure in the HHES group was significantly higher than in HTS, volume resuscitation, and NR groups (respectively, P < 0.05). Animals that received HHES infusion showed a better acid-base balance and renal function. However, there was no significant difference in survival rate between the HTS and NR groups. Furthermore, animals in the HTS group showed a bad acid-base balance and a higher serum sodium level.

CONCLUSIONS

Bolus infusion of HHES combined with normal saline could be an effective therapy for crush syndrome in the early resuscitation period. However, continuous HTS injection was not seemed to be a suitable choice particularly in the absence of monitoring equipment for serum irons or blood gases (institutional protocol no. ZN5R20110016).

Hypertonic resuscitation after severe injury: is it of benefit?

There is a wealth of preclinical data suggesting potential benefit from the administration of hypertonic solutions after severe injury with hypovolemic shock, including improved tissue perfusion, improved flow through the microcirculation, and modulation of the inflammatory response, which may mitigate subsequent organ failure. However, despite these potential advantages, clinical trials of hypertonic resuscitation early after injury have failed to demonstrate significant benefit for resuscitation of hemorrhagic shock, and although there is no difference in overall mortality, there appears to be a trend toward earlier mortality among those receiving hypertonic fluids. Likewise, for TBI there are data suggesting that hypertonic fluids should support cerebral perfusion and mitigate intracranial hypertension, yet the clinical trials of early administration to these patients have also failed to show benefit. Further study is warranted in this patient population, as a longer period of hypertonicity may be required to show a clinical effect. Assessment of long-term neurologic outcome in this patient population remains the gold standard in determining benefit.

Compartmental and muscular response to closed soft tissue injury in rats investigated by oxygen-to-see and intravital fluorescence microscopy

BACKGROUND

Closed soft tissue injury (CSTI) induces local inflammation and progressive microvascular dysfunction. The aim of the study was to evaluate and compare the microvascular changes systematically in a precompartmental tissue injury by oxygen-to-see (O2C), a combined laser Doppler flowmetry and spectrophotometry system, and intravital fluorescence microscopy (IVM).

METHODS

Fourteen Wistar rats were subjected to a trauma and a control group (both n = 7). CSTI was performed on the left lower limb by means of a standardized impact device. Controls received a sham CSTI. Capillary blood flow (QRBC), oxygen saturation (sO2), and postcapillary filling pressure (rHb) were measured noninvasively by O2C assessed in 2-mm and 8-mm depth underneath the skin. Measurements were done before and after trauma and hourly up to 24 hours. IVM of the soleus muscle was performed after 24 hours.

RESULTS

Before CSTI, O2C parameters did not reveal a difference between both groups. Up to 2 hours after trauma, QRBC was significantly increased in 8-mm tissue depth. No significant changes of sO2 and rHb were noted compared with controls. In 2-mm depth, significantly reduced QRBC and rHb levels were observed compared with 8 mm but with no significant changes after CSTI. IVM showed a significant increase of postcapillary blood flow with decreased functional capillary density, increased macromolecular leakage, and increased nicotinamide adenine dinucleotide hydride.

CONCLUSIONS

After CSTI in rats, there was an immediate increase of compartmental capillary blood flow with a slight increase of muscle oxygen saturation and unchanged postcapillary venous filling pressures as sign of a redistribution of blood between soft and muscle tissue. The severity of pathologic changes in the compartment was not reflected by O2C but by IVM.

[Proximal humerus fracture: new aspects in epidemiology, fracture morphology, and diagnostics]

The incidence of proximal humerus fractures is rising and they constitute the third most frequent fracture in the elderly after femoral fractures in the hip area and radius fractures. They are caused by the age-related increase in osteoporosis. In contrast to young people, low-energy trauma involved in simple falls represents the mechanism that leads to the injury in older people. Numerous authors have introduced systems for the classification of proximal humerus fractures.After a thorough clinical examination of the affected extremity including assessment of circulation, motor function, and sensitivity, attention should be directed toward concomitant injuries, especially in the region of the shoulder girdle and thorax. Advocated imaging consists of anteroposterior and axial views of the affected shoulder. Disagreement over management of this fracture is quite considerable and treatment ranges from a conservative approach through to procedures for minimally invasive plate osteosynthesis, open fixed-angle locked plating, and nailing up to prosthetic replacement.

Early fluid resuscitation with hyperoncotic hydroxyethyl starch 200/0.5 (10%) in severe burn injury

Introduction

Despite large experience in the management of severe burn injury, there are still controversies regarding the best type of fluid resuscitation, especially during the first 24 hours after the trauma. Therefore, our study addressed the question whether hyperoncotic hydroxyethyl starch (HES) 200/0.5 (10%) administered in combination with crystalloids within the first 24 hours after injury is as effective as 'crystalloids only' in severe burn injury patients.

Methods

30 consecutive patients were enrolled to this prospective interventional open label study and assigned either to a traditional 'crystalloids only' or to a 'HES 200/0.5 (10%)' volume resuscitation protocol. Total amount of fluid administration, complications such as pulmonary failure, abdominal compartment syndrome, sepsis, renal failure and overall mortality were assessed. Cox proportional hazard regression analysis was performed for binary outcomes and adjustment for potential confounders was done in the multivariate regression models. For continuous outcome parameters multiple linear regression analysis was used.

Results

Group differences between patients receiving crystalloids only or HES 200/0.5 (10%) were not statistically significant. However, a large effect towards increased overall mortality (adjusted hazard ratio 7.12; P = 0.16) in the HES 200/0.5 (10%) group as compared to the crystalloids only group (43.8% versus 14.3%) was present. Similarly, the incidence of renal failure was 25.0% in the HES 200/0.5 (10%) group versus 7.1% in the crystalloid only group (adjusted hazard ratio 6.16; P = 0.42).

Conclusions

This small study indicates that the application of hyperoncotic HES 200/0.5 (10%) within the first 24 hours after severe burn injury may be associated with fatal outcome and should therefore be used with caution.

Trial registration

NCT01120730.

Ebselen reduces inflammation and microvascular perfusion failure after blunt skeletal muscle injury of the rat

BACKGROUND

Soft tissue trauma induces an local inflammatory response and yields a microvascular perfusion failure due to trauma-induced oxidative stress. Using high-resolution multifluorescence microscopy, we herein report on the efficiency of treatment with the oxygen radical scavenger ebselen to improve compromised perfusion of traumatized muscle tissue and to minimize secondary tissue damage.

METHODS

By using a pneumatically driven computer-controlled impact device, closed soft tissue trauma of the left hind limb was induced in pentobarbital-anesthetized rats that received either ebselen (30 mg/kg body weight, intraperitoneally) or equal volumes of the vehicle dimethyl sulfoxide (DMSO). In an additional series of animals, ebselen or DMSO were applied without soft tissue trauma.

RESULTS

Ebselen restored microcirculatory impairment within the injured muscle, as given by values of nutritive perfusion (763 +/- 44 cm/cm2), nicotinamide adenine dinucleotide levels (56 +/- 3 aU) and inflammatory cell interaction (leukocytes: 226 +/- 31 mm(-2)) at 24 hours after trauma, being not different to those found in noninjured muscle tissue of controls. In contrast, skeletal muscle in DMSO-treated animals revealed persistent perfusion failure (564 +/- 32 cm/cm2) with tissue hypoxia (nicotinamide adenine dinucleotide 75 +/- 11 aU) and enhanced endothelial interaction of leukocytes (383 +/- 18 mm(-2)) at 24 hours after trauma.

CONCLUSIONS

Treatment of skeletal muscle soft tissue trauma with the glutathione peroxidase mimic ebselen is highly effective in restoration of disturbed microcirculation. Moreover, reduced inflammatory cell response helps to prevent leukocyte-dependent secondary tissue injury.

Microcirculatory sequelae of the rotator cuff after antegrade nailing in proximal humerus fracture

INTRODUCTION

Antegrade nailing allows a stable fixation and, thus, an early functional after treatment in proximal humerus fractures. Since the surgical procedure in antegrade humeral nailing requires a split of the supraspinatus tendon, the question arises whether the surgical approach causes microcirculatory dysfunction of the tendon.

MATERIALS AND METHODS

A total of 15 consecutive patients suffering from proximal humerus fractures were enrolled. During the implantation of an antegrade humerus nail, microvascular perfusion of the supraspinatus tendon was directly visualized after the exposition and stabilization of the fracture using the OPS-imaging technique.

RESULTS

Immediately after exposure, the nutritive perfusion showed physiological values of tendon microcirculation. After implanting antegrade humeral nails, the perfusion of the supraspinatus tendon reduced markedly. Capillary width was unaffected by the surgical procedure.

CONCLUSION

The trauma leading to proximal humerus fracture causes no fundamental impairment of nutritive perfusion of the rotator cuff. Whereas the implantation of an antegrade humerus nail, which necessarily includes a splitting of the rotator cuff, nearly halves the functional capillary density of the supraspinatus tendon. Even though this effect seems to be reversible, the surgical dissection of the supraspinatus tendon should be performed in a soft tissue sparing way.

Proximal humeral fractures and intramedullary nailing: Experience with a new nail system

OBJECTIVES

The goal of this study was to evaluate fracture healing and alignment as well as functional outcome and complication risks after internal fixation with the intramedullary proximal humeral nail (PHN). This device shows promise for applications involving the reconstruction of the humeral shaft and head with minimal soft tissue stripping and for providing a locked, fixed-angle construct for secure fixation to permit controlled, early, and active rehabilitation.

DESIGN

Prospective case-series.

SETTING

Multicenter study in 11 trauma units.

PATIENTS

One-hundred and fifty-one patients were treated for the same number of proximal humerus fractures.

INTERVENTION

Open reduction and internal fixation with the intramedullary PHN.

MAIN OUTCOME MEASUREMENTS

Occurrence of postoperative complications during and up to 1 year of follow-up. The patients were actively followed up for 1 year with radiological assessment to observe fracture healing, alignment, reduction, and necrosis and by functional outcome measurements, including Constant, Disabilities of the Arm, Shoulder and Hand (DASH), and Neer scores.

RESULTS

A total of 113 patients (77% of 147 surviving patients) were available for the 1-year follow-up assessment, among whom 99% of all examined fractures had healed at this last time point. The range of motion (ROM) of the injured shoulder satisfactorily improved between all of the follow-up periods and by 1 year, 84-92% (ratio of injured to healthy contralateral shoulder) capacity had been achieved for all movements. The Constant score had significantly increased at the 3- and 6-month follow-ups, and by the final 1-year examination, this score attained up to 89% of the contralateral side. The mean baseline DASH was 5.9, with 62% of the total patient population having a zero DASH score. DASH scores higher than the preinjury scores were only observed in patients > 90 years of age, with this score significantly increasing with a mean difference of five points at the 1-year follow-up. At this last examination time point, patients had also reached a "satisfactory" mean Neer score of 85. Intraoperative complications were few (i.e., only four cases were documented) and solely related to the surgical technique; these problems included perforation of the articular surface by the oblique bolt or incorrect positioning of an additional screw. Humeral head necrosis was not common, with only four cases observed. Implant/surgery complications occurred in 63% (30/48) of the patients and included 13 cases of "cut through" (secondary impaction of the humeral head), nine cases of perforation of the articular surface, and four cases of implant loosening. Only four deaths were reported, and all were considered to be purely related to the patient and not to their participation in this study.

CONCLUSION

Nailing of proximal humeral fractures with the PHN is possible, but indication is limited to mainly A- and B-type fractures. The results of this multicenter study with many participating surgeons show that the operative technique is demanding and that the majority of documented complications are related to a violation of published basic technical steps during the operative procedure.

Erythropoietin improves functional and histological recovery of traumatized skeletal muscle tissue

Apart from its hematopoietic effect, erythropoietin (EPO) is known as pleiotropic cytokine with anti-inflammatory and anti-apoptotic properties. Here, we evaluated for the first time the EPO-dependent regeneration capacity in an in vivo rat model of skeletal muscle trauma. A myoblast cell line was used to study the effect of EPO on serum deprivation-induced cell apoptosis in vitro. A crush injury was performed to the left soleus muscle in 80 rats treated with either EPO or saline. Muscle recovery was assessed by analysis of contraction capacities. Intravital microscopy, BrdU/laminin double immunohistochemistry and cleaved caspase-3 immunohistochemistry of muscle tissue on days 1, 7, 14, and 42 posttrauma served for assessment of local microcirculation, tissue integrity, and cell proliferation. Serum deprivation-induced myoblast apoptosis of 23.9 +/- 1.5% was reduced by EPO to 17.2 +/- 0.8%. Contraction force analysis in the EPO-treated animals revealed significantly improved muscle strength with 10-20% higher values of twitch and tetanic forces over the 42-day observation period. EPO-treated muscle tissue displayed improved functional capillary density as well as reduced leukocytic response and consecutively macromolecular leakage over day 14. Concomitantly, muscle histology showed significantly increased numbers of BrdU-positive satellite cells and interstitial cells as well as slightly lower counts of cleaved caspase-3-positive interstitial cells. EPO results in faster and better regeneration of skeletal muscle tissue after severe trauma and goes along with improved microcirculation. Thus, EPO, a compound established as clinically safe, may represent a promising therapeutic option to optimize the posttraumatic course of muscle tissue healing.

Sublethal trauma model with systemic endotoxemia for the study of microcirculatory disorders after the second hit

BACKGROUND

Experimental models often cannot simulate the clinical situation in traumatized patients where the septic second hit finally leads to multiple organ dysfunction syndrome and death. We present an experimental animal model combining initial standardized soft tissue trauma to the left hindlimb of rats with subsequent sublethal systemic endotoxemia.

MATERIALS AND METHODS

This study characterizes the influence of trauma and systemic endotoxemia on nutritive blood flow, inflammatory cell-cell interaction and tissue cell integrity in the traumatized region.

RESULTS

At 24 h after local tissue contusion, in vivo analysis of the skeletal muscle microcirculation by means of high resolution fluorescence microscopy revealed intravascular leukocyte accumulation and impairment of nutritive perfusion with tissue hypoxia. Moreover, muscle tissue damage was characterized by myocyte cell apoptosis. Additional systemic exposure of animals to E. coli lipopolysaccharide at 6 h after soft tissue contusion caused a drop in arterial blood pressure as well as coagulatory disorders, as given by marked thrombocytopenia and reduced thromboplastin times. In double-hit exposed animals, skeletal muscle microcirculation presented with an aggravation of inflammation, perfusion failure, and apoptotic cell death after 24 h.

CONCLUSIONS

This model more closely resembles the scenario of polytraumatized patients with the risk of secondary infections and, thus, is suited to characterize anti-inflammatory drugs with respect to their potential to interfere with microcirculatory disorders and elaboration of disseminated intravascular coagulation after trauma.

Activated protein C reduces tissue hypoxia, inflammation, and apoptosis in traumatized skeletal muscle during endotoxemia

OBJECTIVE

Extensive surgical trauma leads to activation of the coagulation cascade and is often complicated by systemic inflammation and infection. Activated protein C, a natural coagulatory inhibitor, was recently shown to reduce mortality in septic patients. We herein report on the actions of activated protein C on skeletal muscle injury in experimental endotoxemia.

DESIGN

Prospective controlled animal study.

SETTING

University animal research facility.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Closed soft tissue trauma was applied on the left hind limb of pentobarbital-anesthetized rats. Six hours later endotoxemia was induced by intraperitoneal injection of Escherichia coli lipopolysaccharide. An equivalent volume of physiologic saline was given in controls. At the same time point, treatment of animals was started by continuous intravenous application of activated protein C (24 microg/kg.hr) or vehicle solution over 18 hrs. Twenty-four hours after trauma, the extensor digitorum longus muscle was microsurgically exposed and analyzed by means of high-resolution multifluorescence microscopy.

MEASUREMENTS AND MAIN RESULTS

Endotoxemia aggravated traumatized muscle injury, as evidenced by reduced nutritive perfusion, increased tissue hypoxia, enhanced leukocyte-endothelial cell interaction, and apoptotic myocyte cells (249 +/- 17 cm/cm vs. 298 +/- 22 cm/cm; reduced nicotinamide adenine dinucleotide [NADH], 149 +/- 15 arbitrary units [AU] vs. 130 +/- 13 AU; 417 +/- 79 cells/mm vs. 344 +/- 77 cells/mm and 62 +/- 9 cells/mm vs. 31 +/- 5 cells/mm). Therapeutic intervention with activated protein C 6 hrs after trama protected nutritive perfusion and tissue oxygenation (341 +/- 24 cm/cm and 115 +/- 8 AU) and reduced inflammatory leukocyte adherence (185 +/- 60 cells/mm) and cellular apoptosis (15 +/- 4 cells/mm). Of note, the protection of traumatized muscle tissue by activated protein C was also maintained during endotoxemia, as indicated by a functional capillary density of 379 +/- 10 cm/cm, a NADH-fluorescence of 102 +/- 6 AU, a leukocyte adherence of 82 +/- 12 cells/mm, and a myocyte apoptosis of 28 +/- 4 cells/mm.

CONCLUSIONS

Microcirculatory injury of traumatized skeletal muscle tissue is enhanced by intravenous endotoxin application in this model of soft tissue trauma. Activated protein C ameliorates microcirculatory dysfunction and tissue injury, in particular in traumatized animals during endotoxemia.

Prolonged superficial local cryotherapy attenuates microcirculatory impairment, regional inflammation, and muscle necrosis after closed soft tissue injury in rats

BACKGROUND

Closed soft tissue injury induces progressive microvascular dysfunction and regional inflammation. The authors tested the hypothesis that adverse trauma-induced effects can be reduced by local cooling. While superficial cooling reduces swelling, pain, and cellular oxygen demand, the effects of cryotherapy on posttraumatic microcirculation are incompletely understood.

STUDY DESIGN

Controlled laboratory study.

METHODS

After a standardized closed soft tissue injury to the left tibial compartment, male rats were randomly subjected to percutaneous perfusion for 6 hours with 0.9% NaCL (controls; room temperature) or cold NaCL (cryotherapy; 8 degrees C) (n = 7 per group). Uninjured rats served as shams (n = 7). Microcirculatory changes and leukocyte adherence were determined by intravital microscopy. Intramuscular pressure was measured, and invasion of granulocytes and macrophages was assessed by immunohistochemistry. Edema and tissue damage was quantified by gravimetry and decreased desmin staining.

RESULTS

Closed soft tissue injury significantly decreased functional capillary density (240 +/- 12 cm(-1)); increased microvascular permeability (0.75 +/- 0.03), endothelial leukocyte adherence (995 +/- 77/cm(2)), granulocyte (182.0 +/- 25.5/mm(2)) and macrophage infiltration, edema formation, and myonecrosis (ratio: 2.95 +/- 0.45) within the left extensor digitorum longus muscle. Cryotherapy for 6 hours significantly restored diminished functional capillary density (393 +/- 35), markedly decreased elevated intramuscular pressure, reduced the number of adhering (462 +/- 188/cm(2)) and invading granulocytes (119 +/- 28), and attenuated tissue damage (ratio: 1.7 +/- 0.17).

CONCLUSION

The hypothesis that prolonged cooling reduces posttraumatic microvascular dysfunction, inflammation, and structural impairment was confirmed.

CLINICAL RELEVANCE

These results may have therapeutic implications as cryotherapy after closed soft tissue injury is a valuable therapeutic approach to improve nutritive perfusion and attenuate leukocyte-mediated tissue destruction. The risk for evolving compartment syndrome may be reduced, thereby preventing further irreversible aggravation.

Exaggeration of tissue trauma induces signs and symptoms of acute CRPS I, however displays distinct differences to experimental CRPS II

As CRPS I frequently develops after tissue trauma, we proposed that an exaggerated inflammatory response to tissue trauma may underlie CRPS I. Therefore, we studied the vascular inflammatory, nociceptive and apoptotic sequelae of (i) soft tissue trauma and (ii) exaggerated soft tissue trauma in comparison to those of (iii) sciatic nerve chronic constriction injury, modeling CRPS II. Standardized soft tissue trauma (TR) was induced by means of a controlled impact injury technique in the hind limb of pentobarbital-anesthetized rats. Additional animals received soft tissue trauma and femoral arterial infusion of mediator-enriched supernatant achieved by homogenization and centrifugation of traumatized muscle tissue in order to provoke an exaggerated trauma response (ETR). Infusion of supernatant of non-traumatized muscle served as control intervention (STR, sham trauma response). Neuropathy was induced by chronic constriction injury of the sciatic nerve (CCI). Untreated animals served as controls (CO). Detailed nociceptive testing showed temporarily decreased mechanical pain thresholds in ETR animals that resolved within 14 days, while TR and STR animals, i.e. those with singular limb trauma, and controls remained free of pain. Neither cold- nor heat-evoked allodynia developed in post-traumatic animals, whereas CCI animals presented the well-known pattern of ongoing neuropathic pain. Using high-resolution in vivo multifluorescence microscopy, muscle tissue of traumatized animals revealed an enhanced inflammatory response that was found most pronounced in ETR animals. CCI of the sciatic nerve was not accompanied by tissue inflammation; however, induced myocyte apoptosis. Collectively, these data indicate that exaggeration of trauma response induces signs and symptoms of acute CRPS I. Pain perception displays differences to that in CRPS II. Apoptosis turns out to be a distinctive marker for CRPS, warranting further evaluation in clinical studies.

Supernatant of traumatized muscle induces inflammation and pain, but not microcirculatory perfusion failure and apoptotic cell death

Soft tissue trauma induces an inflammatory response locally and in remote organs. Although remote organ failure is attributed to the systemic action of locally released mediators, it is so far unclear to what extent a direct cell injury and the consequences of ischemia or a secondary injury due to locally released mediators contribute to the manifestation of tissue damage at the primary site of trauma. Soft tissue trauma was induced by means of a controlled impact injury technique in the hind limb of pentobarbital-anesthetized rats. Additional animals received a femoral arterial infusion of supernatant of traumatized muscle tissue, of nontraumatized muscle, or 0.9% NaCl. Tissue injury was assessed by determining microcirculatory perfusion failure, inflammatory response, apoptotic cell death, and nociceptive pain behavior. Muscle tissue of traumatized animals revealed perfusion failure, tissue hypoxia, and inflammation. Nociceptive testing showed a decrease in mechanical pain thresholds of the affected hind paw. Infusion of supernatant of traumatized tissue induced local inflammation and pain comparable with that of directly traumatized tissue; however, it failed to cause nutritive perfusion failure. Supernatant of nontraumatized muscle did not affect muscle microcirculation and integrity. Only animals that underwent direct trauma presented with apoptotic cell death, as given by in vivo fluorescence microscopy, caspase 3 protein cleavage, and transferase-mediated dUTP nick-end labeling histology. Trauma-associated humoral factors cause post-traumatic hyperalgesia and inflammation, but not microvascular perfusion failure and apoptotic cell death. This finding may prompt future efforts in the therapy of closed soft tissue trauma to focus not only on antimediator strategies, but to add regimens targeting perfusion failure and tissue apoptosis.

Effects of different resuscitation fluids on tissue blood flow and oxidant injury in experimental rhabdomyolysis

OBJECTIVE

This study was performed to evaluate the effects of 0.9% saline (SAL), 0.9% saline + sodium bicarbonate + mannitol (SAL/BIC/MAN), and hypertonic saline-dextran (HSD) on hemodynamic variables, tissue blood flow, and oxidant injuries in experimental traumatic rhabdomyolysis (TR) in rats subjected allogeneic muscle extract infusion.

DESIGN

Prospective, randomized, experimental.

SETTING

Physiology experiment laboratory.

SUBJECTS

Male Sprague-Dawley rats, weighing 250-300 g.

INTERVENTIONS

All groups (n = 8 each) underwent femoral artery and vein catheterization. The animals in the TR, SAL, SAL/BIC/MAN, and HSD groups received an infusion of 2 mL of autologous muscle extract for 60 mins. After autologous muscle extract infusion, the SAL and HSD groups received 30 mL/kg 0.9% saline for 30 mins or 4 mL/kg HSD for 5 mins, respectively. The SAL/BIC/MAN group received 30 mL/kg 0.9% saline for 30 mins plus a bolus of 1 g/kg mannitol and a bolus of 2 mEq/kg sodium bicarbonate diluted in 1 mL of saline. At 2 hrs of autologous muscle extract infusion, erythrocyte flows in liver and kidney were measured by using a laser Doppler flowmeter. Then, blood samples and kidney and liver biopsies were taken to measure levels of glutathione and malondialdehyde.

MEASUREMENTS AND MAIN RESULTS

TR caused decreases in mean arterial pressure, tissue blood flow, and tissue glutathione and an increase in malondialdehyde. Rats in the HSD group had significant metabolic acidosis. SAL resuscitation did not correct tissue blood flow and prevent oxidant injury. HSD increased tissue blood flow, mean arterial pressure, and liver and kidney glutathione and decreased serum, liver, and kidney malondialdehyde. SAL/BIC/MAN resuscitation corrected all oxidant damage variables but did not increase tissue blood flow. SAL/BIC/MAN preserved serum malondialdehyde and liver glutathione better than the HSD did.

CONCLUSIONS

HSD prevented oxidant injury and restored tissue blood flow but increased metabolic acidosis that followed autologous muscle extract infusion. SAL/BIC/MAN seems to be more effective than HSD in decreasing oxidant injury. Further research on the effects of the solute overload and metabolic acidosis due to HSD resuscitation on renal function in experimental rhabdomyolysis is warranted.

Small volume resuscitation with HyperHaes improves pericontusional perfusion and reduces lesion volume following controlled cortical impact injury in rats

The hyperosmolar and hyperoncotic properties of HyperHaes (HHES) might improve impaired posttraumatic cerebral perfusion. Possible beneficial effects on pericontusional perfusion, brain edema, and contusion volume were investigated in rats subjected to controlled cortical impact (CCI). Male Sprague-Dawley rats (n = 60) anesthetized with isoflurane were subjected to a left temporoparietal CCI. Thereafter, rats were randomized to receive HHES (10% hydroxyethylstarch, 7.5% NaCl) or physiological saline solution (4 mL/kg body weight) intravenously. Mean arterial blood pressure (MABP) and intracranial pressure (ICP) were determined before and following CCI, after drug administration and 24 h later. Regional pericontusional cortical perfusion was determined by scanning laser Doppler flowmetry before CCI, and 30 min, 4 and 24 h after injury. At 24 h brain swelling and water content were measured gravimetrically. At 7 days, cortical contusion volume was determined planimetrically. MABP was not influenced by HHES. ICP was significantly decreased immediately after HHES infusion (5.7 +/- 0.4 vs. 7.1 +/- 1.0 mm Hg; p < 0.05). Pericontusional cortical perfusion was significantly decreased by 44% compared to pre-injury levels (p < 0.05). HHES significantly improved cortical perfusion at 4 h after CCI, approaching baseline values (85 +/- 12%). While increased posttraumatic brain edema was not reduced by HHES at 24 h, cortical contusion volume was significantly decreased in the HHES-treated rats at 7 days after CCI (23.4 +/- 3.5 vs. 39.6 +/- 6.2 mm3; p < 0.05). Intravaneous administration of HHES within 15 min after CCI has a neuroprotective potential, as it significantly attenuated impaired pericontusional perfusion and markedly reduced the extent of induced structural damage.

EFFECTS OF COLLOID RESUSCITATION ON PERIPHERAL MICROCIRCULATION, HEMODYNAMICS, AND COLLOIDAL OSMOTIC PRESSURE DURING ACUTE SEVERE HEMORRHAGE IN RABBITS

We examined the effects of hydroxyethyl starch (HES) on the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of hemorrhagic shock. A total of 40 rabbits was anesthetized with pentobarbital and isoflurane, and they were mechanically ventilated. An ear chamber was prepared to examine blood vessels by intravital microscopy. Shock was induced by removing nearly half of the circulating blood volume. Twenty rabbits received 20 mL of HES by intravenous infusion immediately after blood letting. Additional HES was then administered intravenously to a total volume of 100 mL. The other 20 rabbits (control) were intravenously given 40 mL of lactated Ringer's solution (LR), followed by additional LR to a total volume of 200 mL, administered under the same conditions as HES. After blood letting, arteriolar diameter decreased similarly in the the HES and LR groups (HES, 40.5% +/- 14.8% of the baseline value versus LR, 43.3% +/- 13.1%). After the completion of infusion, arteriolar diameter significantly recovered to 90.8% +/- 10.2% of the baseline value in the HES group as compared with only 62.6% +/- 10.7% in the LR group (P < 0.005). Recovery of arterial blood flow velocity and blood flow rate was also significantly better in the HES group than in the LR group (P < 0.005). Mean arteriolar pressure, central venous pressure, and plasma colloid osmotic pressure after the completion of infusion were significantly greater in the HES group than in the LR group (P < 0.005). We conclude that intravenous infusion of HES effectively maintains the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of acute severe hemorrhage.

In vivo evidence for apoptosis, but not inflammation in the hindlimb muscle of neuropathic rats

Loose ligation of the rat sciatic nerve (chronic constriction injury (CCI) model) provokes signs and symptoms like those observed in complex regional pain syndrome (CRPS) patients. Neurogenic inflammation is a purported cause of neuropathic pain despite inconsistent evidence to support this hypothesis. To clarify this issue, we examined effects of CCI on microcirculation, inflammatory cell-cell interaction and cell integrity in muscle tissue using intravital fluorescence microscopic, molecular and immunohistochemical techniques. CCI-rats, but not sham-operated animals developed symptoms of neuropathic pain and oedema on the ipsilateral hindpaw. Despite signs of neuropathic pain, high resolution in vivo multifluorescence microscopy revealed physiological values for functional capillary density, leukocyte-endothelial cell interaction and microvascular permeability in muscle tissue of CCI-animals, similarly as found in controls, indicating absence of perfusion failure and inflammatory cell reaction. However, CCI-animals represented with marked apoptosis of bisbenzimide-stained muscle tissue cells, as given by in vivo fluorescence microscopic assessment of cell death-associated condensation, fragmentation and/or crescent-shaped formation of their nuclear chromatin. Apoptosis was further confirmed by increased caspase 3 protein levels and positive terminal deoxyuridine nick end labeling histochemistry. The present study demonstrates that sciatic nerve ligation-induced neuropathy causes cell apoptosis without concomitant inflammation-associated microcirculatory dysfunction in muscle tissue. Beside the well-known pattern of neuropathic pain, the CCI-model has now additionally been shown to reflect the response of muscle tissue to impaired innervation, i.e. prompting muscle cells to undergo non-inflammatory apoptotic cell death. This finding deserves further investigation in that apoptosis may contribute to neuropathic pain conditions like CRPS.