Progesterone administration after trauma and hemorrhagic shock improves cardiovascular responses

Role of pregnancy hormones and hormonal interaction on the maternal cardiovascular system: a literature review

Hormones have a vital duty in the conservation of physiological cardiovascular function during pregnancy. Alterations in oestrogen, progesterone and prolactin levels are associated with changes in the cardiovascular system to support the growing foetus and counteract pregnancy stresses. Pregnancy hormones are, however, also linked to numerous pathophysiological outcomes on the cardiovascular system. The expression and effects of the three main pregnancy hormones (oestrogen, prolactin and progesterone) vary depending on the gestation period. However, the reaction of a target cell also depends on the abundance of hormone receptors and impacts put forth by other hormones. Hormonal interaction may be synergistic, antagonistic or permissive. It is crucial to explore the cross talk of pregnancy hormones during gestation, as this may have a greater impact on the overall changes to the cardiovascular system.

The influence of sex steroid hormones on the response to trauma and burn injury

Trauma and related sequelae result in disturbance of homeostatic mechanisms frequently leading to cellular dysfunction and ultimately organ and system failure. Regardless of the type and severity of injury, gender dimorphism in outcomes following trauma have been reported, with females having lower mortality than males, suggesting that sex steroid hormones (SSH) play an important role in the response of body systems to trauma. In addition, several clinical and experimental studies have demonstrated the effects of SSH on the clinical course and outcomes following injury. Animal studies have reported the ability of SSH to modulate immune, inflammatory, metabolic and organ responses following traumatic injury. This indicates that homeostatic mechanisms, via direct and indirect pathways, can be maintained by SSH at local and systemic levels and hence result in more favourable prognosis. Here, we discuss the role and mechanisms by which SSH modulates the response of the body to injury by maintaining various processes and organ functions. Such properties of sex hormones represent potential novel therapeutic strategies and further our understanding of current therapies used following injury such as oxandrolone in burn-injured patients.

Insulin alleviates posttrauma cardiac dysfunction by inhibiting tumor necrosis factor-α-mediated reactive oxygen species production

OBJECTIVE

Clinical evidence indicates that intensive insulin treatment prevents the incidence of multiple organ failures in surgical operation and severe trauma, but the mechanisms involved remain elusive. This study was designed to test the hypothesis that insulin may exert anti-inflammatory and antioxidative effects and thus alleviate cardiac dysfunction after trauma.

DESIGN

Prospective, randomized experimental study.

SETTING

Animal research laboratory.

SUBJECTS

Sprague Dawley rats.

INTERVENTIONS

Anesthetized rats were subjected to 200 revolutions at a rate of 35 rpm in Noble-Collip drum to induce a nonlethal mechanical trauma and were randomized to receive vehicle, insulin, and insulin + wortmannin treatments. An in vitro study was performed on cultured cardiomyocytes subjected to sham-traumatic serum (SS), traumatic serum (TS), SS + tumor necrosis factor (TNF)-α, SS + H2O2, TS + neutralizing anti-TNF-α antibody, or TS + tempol treatments.

MEASUREMENTS AND MAIN RESULTS

Immediate cardiac dysfunction occurred 0.5 hr after trauma without significant cardiomyocyte necrosis and apoptosis, while serum TNF-α and cardiac reactive oxygen species (ROS) production was increased. Importantly, incubation of cardiomyocytes with TS or SS + TNF-α significantly increased ROS generation together with dampened cardiomyocyte contractility and Ca transient, all of which were rescued by TNF-α antibody. Administration of insulin inhibited TNF-α and ROS overproduction and alleviated cardiac dysfunction 2 hours after trauma. Scavenging ROS with tempol also attenuated cardiac dysfunction after trauma, whereas insulin combined with tempol failed to further improve cardiac functional recovery compared with insulin treatment alone. Moreover, the aforementioned anti-TNF-α, antioxidative, and cardioprotective effects afforded by insulin were almost abolished by the phosphatidylinositol 3-kinase inhibitor wortmannin.

CONCLUSIONS

These results demonstrate for the first time that mechanical trauma induces a significant increase in TNF-α and ROS production, resulting in immediate cardiac dysfunction. Early posttrauma insulin treatment alleviates cardiac dysfunction by inhibiting TNF-α-mediated ROS production via a phosphatidylinositol 3-kinase/Akt-dependent mechanism.

NAD(P)H:quinone oxidoreductase 1 is induced by progesterone in cardiomyocytes

NAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes two-electron reduction of various quinones by utilizing NAD(P)H as an electron donor. Our previous study found that progesterone (PG) can protect cardiomyocytes from apoptosis induced by doxorubicin (Dox). Microarray analyses of genes induced by PG had led to the discovery of induction of NQO1 mRNA. We report here that PG induces NQO1 protein and its activity in a dose-dependent manner. Whereas NQO1 is well known as a target gene of Nrf2 transcription factor due to the presence of antioxidant response element (ARE) in the promoter, PG did not activate the ARE, suggesting Nrf2-independent induction of NQO1. To address the role of NQO1 induction in PG-induced cytoprotection, we tested the effect of NQO1 inducer β-naphthoflavone and inhibitor dicoumarol. Induction of NQO1 by β-naphthoflavone decreased Dox-induced apoptosis and potentiated the protective effect of PG as measured by caspase-3 activity. PG-induced NQO1 activity was inhibited with dicoumarol, which did not affect PG-induced cytoprotection. Dicoumarol treatment alone potentiated Dox-induced caspase-3 activity. These data suggest that while NQO1 plays a role in PG-induced cytoprotection, there are additional components contributing to PG-induced cytoprotection.

Inhibition of apoptosis by progesterone in cardiomyocytes

While gender-based differences in heart disease have raised the possibility that estrogen (ES) or progesterone (PG) may have cardioprotective effects, recent controversy regarding hormone replacement therapy has questioned the cardiac effects of these steroids. Using cardiomyocytes, we tested whether ES or PG has protective effects at the cellular level. We found that PG but not ES protects cardiomyocytes from apoptotic cell death induced by doxorubicin (Dox). PG inhibited apoptosis in a dose-dependent manner, by 12 ± 4.0% at 1 μm and 60 ± 1.0% at 10 μm. The anti-apoptotic effect of PG was also time dependent, causing 18 ± 5% or 62 + 2% decrease in caspase-3 activity within 1 h or 72 h of pretreatment. While PG causes nuclear translocation of its receptor within 20 min, the cytoprotective effect of PG was canceled by mifepristone (MF), a PG receptor antagonist. Analyses using Affymetrix high-density oligonucleotide array and RT-PCR found that PG induced Bcl-xL, metallothionine, NADPH quinone oxidoreductase 1, glutathione peroxidase-3, and four isoforms of glutathione S-transferase. Western blot analyses revealed that PG indeed induced an elevation of Bcl-xL protein in a dose- and time-dependent manner. Nuclear run-on assay indicated that PG induced Bcl-xL gene transcription. Inhibiting the expression of Bcl-xL using siRNA reduced the cytoprotective effect of PG. Our data suggests that PG induces a cytoprotective effect in cardiomyocytes in association with induction of Bcl-xL gene.

Mechanism of salutary effects of estrogen on cardiac function following trauma-hemorrhage: Akt-dependent HO-1 up-regulation

OBJECTIVES

Because administration of 17beta-estradiol following trauma-hemorrhage improves cardiovascular responses, we investigated whether the salutary effects of 17beta-estradiol on cardiac function are mediated via Akt-dependent heme oxygenase-1 up-regulation under those conditions.

DESIGN

Experimental animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Rats underwent trauma-hemorrhage (mean blood pressure approximately 40 mm Hg for 90 mins) followed by fluid resuscitation. Before resuscitation, rats received either vehicle, 17beta-estradiol (1 mg/kg), or 17beta-estradiol plus the phosphoinositide 3-kinase inhibitor wortmannin (1 mg/kg). At 2 hrs after trauma-hemorrhage or sham operation, the rats were killed.

MEASUREMENTS AND MAIN RESULTS

Cardiac function, heart tissue myeloperoxidase activity, cardiac and circulatory cytokine levels, cardiac intercellular adhesion molecule-1, and chemokine levels were measured. Cardiac Akt and heme oxygenase-1 were also determined. We found that 17beta-estradiol prevented the trauma-hemorrhage-induced impairment in cardiac function and increase in cardiac myeloperoxidase activity. Cardiac and systemic interleukin-6 and tumor necrosis factor-alpha levels as well as cardiac intercellular adhesion molecule-1, cytokine-induced neutrophil chemoattractant-1, and macrophage inflammatory protein-2 contents were increased following trauma-hemorrhage, which were normalized by 17beta-estradiol. Administration of 17beta-estradiol following trauma-hemorrhage restored cardiac Akt phosphorylation and further increased heme oxygenase-1 expression. Coadministration of wortmannin following trauma-hemorrhage abolished the previous effects by 17beta-estradiol.

CONCLUSIONS

These results suggest that the 17beta-estradiol-meditated improvement in cardiac function following trauma-hemorrhage occurs via Akt-dependent heme oxygenase-1 up-regulation.

The role of estrogen and receptor agonists in maintaining organ function after trauma-hemorrhage

Sex is increasingly recognized as a major factor in the outcome of patients who have trauma and sepsis. Moreover, sex steroids influence chemokine/adhesion molecule expression and neutrophil accumulation. Heat shock proteins, heat shock factor 1, and peroxisome proliferator-activated receptor [gamma] coactivator 1 are regulated by the estrogen receptors and consequently contribute to organ protection after trauma-hemorrhage. Additionally, sex steroids regulate inflammatory cytokines, leading to increased morbidity and mortality. This article deals with trauma-hemorrhage and examines the following: 1) the evidence for sex differences; 2) the mechanisms by which sex hormones affect organ protection; 3) the tissue-specific effect of sex hormone receptors; and 4) the effect of genomic and nongenomic (i.e. membrane-initiated steroid signaling) pathways of sex hormones after trauma. The available information indicates that sex steroids modulate cardiovascular responses after trauma. Thus, alteration or modulation of the prevailing hormone milieu at the time of injury seems to be a novel therapeutic option for improving outcome after injury

Multifunctional drugs for head injury

Traumatic brain injury (TBI) remains one of the leading causes of mortality and morbidity worldwide in individuals under the age of 45 years, and, despite extensive efforts to develop neuroprotective therapies, there has been no successful outcome in any trial of neuroprotection to date. In addition to recognizing that many TBI clinical trials have not been optimally designed to detect potential efficacy, the failures can be attributed largely to the fact that most of the therapies investigated have been targeted toward an individual injury factor. The contemporary view of TBI is that of a very heterogenous type of injury, one that varies widely in etiology, clinical presentation, severity, and pathophysiology. The mechanisms involved in neuronal cell death after TBI involve an interaction of acute and delayed anatomic, molecular, biochemical, and physiological events that are both complex and multifaceted. Accordingly, neuropharmacotherapies need to be targeted at the multiple injury factors that contribute to the secondary injury cascade, and, in so doing, maximize the likelihood of a successful outcome. This review focuses on a number of such multifunctional compounds that have shown considerable success in experimental studies and that show maximum promise for success in clinical trials.

Bench-to-bedside review: latest results in hemorrhagic shock

Hemorrhagic shock is a leading cause of death in trauma patients worldwide. Bleeding control, maintenance of tissue oxygenation with fluid resuscitation, coagulation support, and maintenance of normothermia remain mainstays of therapy for patients with hemorrhagic shock. Although now widely practised as standard in the USA and Europe, shock resuscitation strategies involving blood replacement and fluid volume loading to regain tissue perfusion and oxygenation vary between trauma centers; the primary cause of this is the scarcity of published evidence and lack of randomized controlled clinical trials. Despite enormous efforts to improve outcomes after severe hemorrhage, novel strategies based on experimental data have not resulted in profound changes in treatment philosophy. Recent clinical and experimental studies indicated the important influences of sex and genetics on pathophysiological mechanisms after hemorrhage. Those findings might provide one explanation why several promising experimental approaches have failed in the clinical arena. In this respect, more clinically relevant animal models should be used to investigate pathophysiology and novel treatment approaches. This review points out new therapeutic strategies, namely immunomodulation, cardiovascular maintenance, small volume resuscitation, and so on, that have been introduced in clinics or are in the process of being transferred from bench to bedside. Control of hemorrhage in the earliest phases of care, recognition and monitoring of individual risk factors, and therapeutic modulation of the inflammatory immune response will probably constitute the next generation of therapy in hemorrhagic shock. Further randomized controlled multicenter clinical trials are needed that utilize standardized criteria for enrolling patients, but existing ethical requirements must be maintained.

Use of a pediatric cohort to examine gender and sex hormone influences on outcome after trauma

BACKGROUND

Animal studies suggest that female gender imparts a protective effect on outcome after trauma, and implicate sex hormones as the cause. Human studies have yielded mixed results. These results are confounded by postmenopausal hormone replacement and the difficulty of controlling for pretrauma comorbidities. The pediatric population is a better model to determine the impact of gender and sex hormones on outcome after trauma.

METHODS

The National Trauma Data Bank was queried for all patients from birth to 20 years of age. Age, gender, Injury Severity Score (ISS), mechanism of injury, mortality, intensive care unit days, and ventilator days were examined. To control for the effect of sex hormones, patients were divided into three groups by age: prepubertal (birth to 8 years), peripubertal (8.1-14.5 years), and postpubertal (14.6-20 years). We calculated survival rates for age group ISS subsets overall and by mechanism of injury.

RESULTS

The prepubertal and peripubertal age groups had equivalent survival rates between genders across all severities of injury. The sex hormone-containing postpubertal cohort had a significantly improved survival rate for women across all ISS subgroups, and the effect was more pronounced with increasing ISS. This effect was despite a higher mean ISS for women at these greater magnitudes of injury. The cause of this effect could not be explained by mechanism of injury, ventilator days, or intensive care unit days.

CONCLUSION

Female gender was associated with improved survival rates for patients demonstrating sex hormone production (i.e. postpubescent patients) in a manner that was directly proportional to their severity of injury. No protective effect of gender was seen in the prepubescent or peripubertal age groups.

Metabolic modulators following trauma sepsis: Sex hormones

BACKGROUND

The development of metabolic perturbations following severe trauma/sepsis leading to decreased energy production, hyperglycemia, and lipolysis is often rapid. Gender is increasingly recognized as a major factor in the outcome of patients suffering from trauma/sepsis. Moreover, sex hormones influence energy, glucose, and lipid metabolism. Metabolic modulators, such as peroxisome proliferator-activated receptor-gamma coactivator-1 and peroxisome proliferator-activated receptor-alpha, which are required for mitochondrial energy production and fatty acid oxidation, are regulated by the estrogen receptor-beta and consequently contribute to cardioprotection following trauma hemorrhage. Additionally, sex steroids regulate inflammatory cytokines that cause hypermetabolism/catabolism via acute phase response, leading to increased morbidity and mortality.

MEASUREMENTS

This article examines the following: (1) the evidence for gender differences; (2) energy, glucose, and lipid metabolism and the acute phase protein response; (3) the mechanisms by which gender/sex hormones affect the metabolic modulators; and (4) the tissue-specific effect of sex hormone receptors and the effect of genomic and nongenomic pathways of sex hormones following trauma.

RESULTS AND CONCLUSIONS

The available information indicates that sex steroids not only modulate the immune/cardiovascular responses but also influence various metabolic processes following trauma. Thus, alteration or modulation of the prevailing hormone milieu at the time of injury appears to be a novel therapeutic adjunct for improving outcome after injury.

The enantiomer of progesterone acts as a molecular neuroprotectant after traumatic brain injury

Previous work shows that neurosteroid enantiomers activate specific molecular receptors that relay neuroprotection. However, the actions of the enantiomer of progesterone (ent-PROG) at the PROG receptor (PR) are unknown. PR binding and transcriptional assays were performed to determine the actions of ent-PROG at the classical PR. Additionally, the neuroprotective effects of ent-PROG in traumatic brain injury (TBI) were investigated and compared to the actions of PROG and its metabolite allopregnanolone (ALLO), both of which have been shown to have neuroprotective properties when given after TBI. Binding studies performed in COS cells over-expressing the PR showed that ent-PROG inhibited PROG binding to the PR. In contrast, ent-PROG did not activate PR-mediated transcription. Rats received bilateral medial frontal cortex injury followed by treatments at 1, 6, 24 and 48h with PROG, ALLO or ent-PROG. Brains were processed for edema, protein and enzyme activity. ent-PROG treatment in vivo decreased cerebral edema, cell death mediators, inflammatory cytokines, and reactive gliosis, and increased antioxidant activity. These findings suggest that the progestin-mediated pro-survival response seen with TBI is regulated either independently of the classical PR or via nongenomic PR-regulated actions.

A role of PPAR-gamma in androstenediol-mediated salutary effects on cardiac function following trauma-hemorrhage

OBJECTIVE

To examine the mechanism by which androstenediol improves cardiac function following trauma-hemorrhage (T-H).

SUMMARY BACKGROUND DATA

Androstenediol administration improves cardiovascular function and attenuates proinflammatory cytokine production following T-H. Activation of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has been shown to be protective following ischemic conditions. We hypothesized that PPAR-gamma activation plays a role in the androstenediol-mediated salutary effects on cardiac function following T-H.

METHODS

Male rats underwent laparotomy and hemorrhagic shock (40 mm Hg for 90 minutes), followed by resuscitation with 4 times the shed blood volume in the form of Ringer's lactate. Androstenediol (1 mg/kg body weight, i.v.) was administrated at the end of resuscitation. In a separate group of animals, a PPAR-gamma antagonist (GW9662) was administered simultaneously with androstenediol and animals were killed at 5 hours thereafter.

RESULTS

A decrease in cardiac function and an increase in IL-6 and iNOS gene expression were observed following T-H. Androstenediol treatment normalized cardiac function, increased PPAR-gamma DNA binding activity, attenuated IL-6 and iNOS gene expressions, and reduced plasma IL-6. Plasma 15-deoxy-Delta12, 14-prostaglandin J2 (PGJ2, an endogenous PPAR-gamma agonist) levels were also increased in androstenediol-treated T-H rats, but these levels were lower than those observed in shams. Coadministration of PPAR-gamma antagonist along with androstenediol, however, prevented the androstenediol-mediated reduction in cardiac iNOS and IL-6 expressions and abolished the improvements in cardiac function.

CONCLUSION

The androstenediol-mediated salutary effects on cardiac function following T-H appear to be mediated at least in part via PPAR-gamma activation, which down-regulates IL-6 and iNOS gene expression in the heart.

Androstenediol administration after trauma-hemorrhage attenuates inflammatory response, reduces organ damage, and improves survival following sepsis

Although androstenediol (adiol or 5-androstene-3beta,17beta-diol), a metabolite of dehydroepiandrosterone (DHEA), has protective effects following trauma-hemorrhage (T-H), it remains unknown whether administration of adiol has any salutary effects on the inflammatory response and outcome following a combined insult of T-H and sepsis. Male rats underwent T-H shock [mean arterial pressure (MAP) 40 mmHg for 90 min] followed by resuscitation. Adiol (1 mg/kg body wt) or vehicle was administered at the end of resuscitation. Sepsis was induced by cecal ligation and puncture (CLP) at 20 h after T-H or sham operation. Five hours after CLP, plasma and tissue samples were analyzed for cytokines (IL-6 and IL-10), MPO, neutrophil chemotactic factor (CINC-3), and liver injury (alanine aminotransferase and lactate dehydrogenase). In another group of rats, the gangrenous cecum was removed at 10 h after CLP, the cavity was irrigated with warm saline and closed in layers, and mortality was recorded over 10 days. T-H followed by CLP produced a significant elevation in plasma IL-6 and IL-10 levels, enhanced neutrophil cell activation, and resulted in liver injury. Adiol administration prevented the increase in cytokine production, neutrophil cell activation, and attenuated liver injury. Moreover, rats subjected to the combined insult, receiving vehicle or adiol, had a 50% and 6% mortality, respectively. Since adiol administration suppresses proinflammatory cytokines, reduces liver damage, and decreases mortality after the combined insult of T-H and sepsis, this agent appears to be a novel adjunct to fluid resuscitation for decreasing T-H-induced septic complications and mortality.

Gonadal steroids in critical illness

Gonadal steroids are metabolized in target cells and then interact with specific receptors to exert genomic and nongenomic effects. Complex feedback loops that involve the immune-neuroendocrine axis, limbic system, and gonadal steroids play a vital role in the adaptation to critical illness. Preclinical studies demonstrate adverse physiological effects of androgens on the cardiovascular and immune systems despite its purported anabolic effects. Similar models also demonstrate salutary effects of estrogens on these systems. Thus, during the catabolic phases of acute and chronic critical illness, estrogen, and not androgen, therapy may prove to be a valuable intervention. However, during the post-critical illness recovery phase, when anabolism is critical, androgen therapy may still be useful and safe.

The neuroprotective effect of progesterone after traumatic brain injury in male mice is independent of both the inflammatory response and growth factor expression

Previous studies suggest that progesterone may possess neuroprotective properties after traumatic insult but, with the exception of reduced formation of cerebral oedema, limited experimental evidence has been presented to support this claim. In the present study we focused on the effect of progesterone treatment on structural and functional deficits in an experimental model of traumatic brain injury. Female mice exhibited significantly (P = 0.0445) reduced lesion volumes compared with males after aseptic cryogenic cerebral injury (ACI), suggesting that female sex steroids provide protection against this injury. In male mice, progesterone treatment after injury (three intraperitoneal doses of 8 mg/kg) reduced lesion volume (P = 0.0429) and improved performance in a spatial cognitive task (Morris water maze; P = 0.0014). However, progesterone had no demonstrable effect on the formation of oedema as measured using T2-weighted magnetic resonance imaging, nor did it affect brain water content. The pro-inflammatory cytokines TNF-alpha and IL-1beta, and growth factors BDNF and G-CSF, were all strongly transcriptionally activated after ACI. However, progesterone administration did not affect expression of these genes. This study provides strong evidence that progesterone possesses neuroprotective properties in a mouse model of traumatic brain injury, but suggests that the steroid achieves this effect through mechanism(s) independent of the inflammatory response or growth factor up-regulation.

Recent advances in the development of multifactorial therapies for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of death and disability in the industrialised world and remains a major health problem with serious socioeconomic consequences. So far, despite encouraging preclinical results, almost all neuroprotection trials have failed to show any significant efficacy in the treatment of clinical TBI. This may be due, in part, to the fact that most of the therapies investigated have targeted an individual injury factor. It is now recognised that TBI is a very heterogeneous type of injury that varies widely in its aetiology, clinical presentation, severity and pathophysiology. The pathophysiological sequelae of TBI are mediated by an interaction of acute and delayed molecular, biochemical and physiological events that are both complex and multifaceted. Accordingly, a successful TBI treatment may have to simultaneously attenuate many injury factors. Recent efforts in experimental TBI have, therefore, focused on the development of neuropharmacotherapies that target multiple injury factors and thus improve the likelihood of a successful outcome. This review will focus on three such novel compounds that are currently being assessed in clinical trials; progesterone, dexanabinol and dexamethasone, and provide an update on the progress of both magnesium and cyclosporin A.

SEVERITY OF EMERGENCY DEPARTMENT HYPOTENSION PREDICTS ADVERSE HOSPITAL OUTCOME

Arterial hypotension often signifies inadequate systemic perfusion. We hypothesize that in a heterogeneous emergency department (ED) population with clinically suspected circulatory shock, the severity of hypotension on presentation predicts in-hospital outcome. We performed a secondary analysis of patients with nontraumatic shock enrolled in a noninterventional, randomized, controlled trial. The setting was an urban, tertiary ED, census >100,000 visits per year. Patients included nontrauma ED patients, aged >17 years, with initial ED vital signs consistent with shock (systolic blood pressure <100 mmHg or shock index >1.0), and agreement of two independent observers for at least one sign and symptom of inadequate tissue perfusion. Measurements included interobserver agreement for signs and symptoms of shock, relationship between the depth and duration of ED hypotension and adverse hospital outcome (in-hospital mortality, need for intensive care unit services, and acute organ failure) and logistic regression analysis for independent predictors of adverse hospital outcome. Of 202 patients who qualified, 190 patients were included; the in-hospital mortality rate was 15%. The sign or symptom of shock with the highest interobserver agreement was "unresponsive" (kappa = 0.74). The adverse hospital outcomes increased with each decile decrease in the lowest ED systolic blood pressure (SBP) from 17% if SBP >89 mmHg versus 50% if SBP < 80 mmHg. Forty percent of patients with an adverse hospital outcome had sustained hypotension (all ED SBP <100 mmHg for > or =60 min). Sustained hypotension was the strongest independent predictor of an adverse hospital outcome (odds ratio 3.1; 95% CI 1.5-7.1). Mortality among patients who present to the ED with undifferentiated shock is high. The depth and duration of systolic blood pressure appears to have a dose-response relationship to adverse hospital outcome.

Female Sex Hormones Protect Red Blood Cells from Damage after Trauma-Hemorrhagic Shock

BACKGROUND

Trauma/hemorrhagic shock (T/HS) is known to cause changes in red blood cell (RBC) deformability and resting shape. Our previous studies have shown that proestrus female rats are more protected from shock-induced RBC damage than diestrus females or males. However, it is unclear whether female or male sex hormones can influence the severity of these alterations.

METHODS

Red blood cell deformability and shape were examined in proestrus female rats, and oophorectomized female rats, as well as in castrated and non-castrated male rats (5-10 animals per group) subjected to T/HS. Red blood cell deformability was measured by laser ektacytometry whereas erythrocyte shape was evaluated by scanning electron microscopy.

RESULTS

Proestrus female rats subjected to T/HS did not show either significant RBC deformability changes (decrease in elongation index) or shape alterations (increase in the percentage of reversibly and irreversibly changed cells). Oophorectomized rats demonstrated more severe RBC changes than did non-oophorectomized rats. The degree of RBC damage was the same in castrated and non-castrated males, which was significantly worse than in proestrus females.

CONCLUSIONS

Removal of female sex hormones increases the severity of T/HS-induced RBC changes, indicating that female sex hormones protect against RBC damage. In contrast, male sex hormones do not appear to modulate T/HS RBC dysfunction.