Arginine vasopressin: the future of pressure-support resuscitation in hemorrhagic shock

Sex-specific issues of central and peripheral arginine-vasopressin concentrations in neurocritical care patients

BACKGROUND

Arginine-Vasopressin (AVP) is a nonapeptide that exerts multiple functions within the central nervous system and in the blood circulation that might contribute to outcome in critically ill patients. Sex differences have been found for mental and physical effects of AVP. For example, stress response and response due to hemorrhage differ between males and females, at least in animal studies. Data on humans -especially on AVP within the central nervous system (CNS)-are scarce, as cerebrospinal fluid (CSF) which is said to represent central AVP activity, has to be collected by means of invasive procedures. Here we present data on 30 neurocritical care patients where we simultaneously collected blood, CSF and saliva to analyze concentrations in the central and peripheral compartments.

PATIENTS AND METHODS

30 neurocritical care patients were included (13 male, 13 postmenopausal female, 4 premenopausal female) with a median age of 60 years. CSF, plasma and saliva were obtained simultaneously once in each patient and analyzed for AVP concentrations. Correlations between the central compartment represented by CSF, and the peripheral compartment represented by plasma and saliva, were identified. Relations between AVP concentrations and serum sodium and hematocrit were also determined.

RESULTS

In the whole patient collective, only very weak to weak correlations could be detected between AVP plasma/CSF, plasma/saliva and CSF/saliva as well as between AVP concentrations in each of the compartments and serum sodium/hematocrit. Regarding the subgroup of postmenopausal females, a significant moderate correlation could be detected for AVP in plasma and CSF and AVP CSF and serum sodium.

CONCLUSION

Absolute concentrations of AVP in central and peripheral compartments did not show sex differences. However, correlations between AVP plasma and CSF and AVP CSF and serum sodium in postmenopausal females indicate differences in AVP secretion and AVP response to triggers that deserve further examination.

Vitamin C in surgical sepsis

PURPOSE OF REVIEW

The current review discusses the supplemental use of vitamin C as an adjunct in the management of sepsis and septic shock.

RECENT FINDINGS

The antioxidant properties of vitamin C are touted to be useful in modulating the inflammatory response, decreasing vasopressor requirements, and improving resuscitation. Current resuscitation practices are focused on addressing the hemodynamic instability and ensuring adequate oxygen delivery to tissues. The conceptual framework of the use of vitamin C during a resuscitation is to modulate in a beneficial fashion the inflammatory response to sepsis while concomitantly resuscitating and treating the infection. While there is promising animal and burn-related data on improved fluid resuscitation with the use of vitamin C as an adjunct, the most recent meta-analyses of the available data fail to show a survival benefit in sepsis, and concerns regarding nephrotoxicity remain.

SUMMARY

Although there are large number of animal studies, only a few small prospective and retrospective studies in humans address the use of vitamin C to treat sepsis. Further research in a controlled and randomized fashion is needed to determine if vitamin C is effective in this role. While there is a promise of ascorbate's addition to the sepsis bundle as an adjunct to resuscitation, the evidence is not conclusive.

Absence of a diurnal rhythm of oxytocin and arginine-vasopressin in human cerebrospinal fluid, blood and saliva

PURPOSE

The aims of our study were to determine first circadian influences on central concentrations of the neuropeptides oxytocin and arginine-vasopressin and second to investigate if these central concentrations are associated with those in the peripheral compartments blood and saliva in neurocritical care patients. We therefore included patients with external ventricular drain who attended a neurosurgical intensive care unit and were not exposed to painful or stressful stimuli during the sampling period. For this purpose, blood, cerebrospinal fluid and saliva were collected in a 24-hour-interval at the timepoints 06:00, 12:00, 18:00 and 24:00.

RESULTS

In none of the three body fluids examined, significant time-dependent fluctuations of oxytocin and arginine-vasopressin concentrations could be detected during the 24-hour sampling period. The only exception was the subgroup of postmenopausal women whose oxytocin concentrations in cerebrospinal fluid at 12:00 were significantly higher than at 18:00. Correlations of blood and cerebrospinal fluid and blood and saliva neuropeptide levels were very weak to weak at each timepoint. Cerebrospinal fluid and saliva oxytocin levels showed a moderate correlation at 06:00 but did correlate very weak at the other timepoints.

CONCLUSIONS

Central as well as peripheral oxytocin and arginine-vasopressin concentrations in neurocritical care patients did not show significant diurnal fluctuations. No strong correlations between central and peripheral neuropeptide concentrations could be detected under basal conditions. If investigators even though decide to use saliva concentrations as surrogate parameter for central neuropeptide activity, they have to consider that correlations of cerebrospinal fluid and saliva oxytocin seem to be highest in the early morning.

Arginine vasopressin improves cerebral perfusion following controlled haemorrhage in adult ewes

KEY POINTS

Traumatic haemorrhagic shock carries significant morbidity and mortality related to the severity and duration of tissue hypoperfusion, much of which occurs in the pre-hospital environment where therapy must be easy to use and would augment, not replace, local haemorrhage control measures. Vasopressor therapy use in haemorrhagic shock remains controversial. Potential benefits from improved blood pressure and tissue perfusion need to be weighed against possible harm from increased blood loss if haemorrhage is uncontrolled. We demonstrate that 20 IU I.M. vasopressin produces a progressive, sustained and clinically significant increase in blood pressure and carotid blood flow compared to 1 mg I.M. adrenaline or placebo in an animal model of controlled haemorrhagic shock. I.M. vasopressin may play a role in the early management of haemorrhagic shock by improving cerebral perfusion and haemodynamic stability; however, further studies are required to establish the potential benefit against the risk of exacerbating haemorrhage, if it is uncontrolled.

ABSTRACT

Haemorrhagic shock causes significant morbidity and mortality. Novel pre-hospital therapy to improve haemodynamic stability and cerebral perfusion may improve outcomes but remains controversial. In an ovine model of controlled haemorrhagic shock, the effects of early intramuscular arginine vasopressin (AVP), adrenaline or placebo on haemodynamic stability and cerebral perfusion were compared. Carotid pressure and flow catheters were placed in healthy, anaesthetized adult ewes. Frontal cortex cerebral oxygenation was measured using near infrared spectroscopy. Controlled, rapid, haemorrhage (∼30% estimated blood volume) was induced. Five minutes post-bleed a 1 ml intramuscular dose of 0.9% saline, adrenaline 1 mg or AVP 20 IU was administered. Carotid blood pressure and flow improved significantly in the AVP group over the first 30 min post-intervention. To emulate standard trauma care, 1 L of 0.9% saline was infused 30 min post-bleed followed by re-transfusion of the sheep's own blood at 60 min post-bleed. Carotid blood pressure and flow in the AVP group remained significantly higher post-crystalloid infusion, but this difference was lost post-blood transfusion. Data were analysed by two-way ANOVA with time, group as the main factors. When compared to saline or adrenaline, a single dose of intramuscular AVP resulted in a progressive and sustained increase in carotid artery blood pressure and flow with commensurate increase in cerebral oxygenation. Intramuscular AVP has potential as an emergency pre-hospital therapy following exsanguinating haemorrhage; however, further studies are required to investigate whether the benefit of improved perfusion pressure outweighs the risks of exacerbating ongoing bleeding.

Effects of the Kv7 voltage-activated potassium channel inhibitor linopirdine in rat models of haemorrhagic shock

Recently, we demonstrated that Kv7 voltage-activated potassium channel inhibitors reduce fluid resuscitation requirements in short-term rat models of haemorrhagic shock. The aim of the present study was to further delineate the therapeutic potential and side effect profile of the Kv7 channel blocker linopirdine in various rat models of severe haemorrhagic shock over clinically relevant time periods. Intravenous administration of linopirdine, either before (1 or 3 mg/kg) or after (3 mg/kg) a 40% blood volume haemorrhage, did not affect blood pressure and survival in lethal haemorrhage models without fluid resuscitation. A single bolus of linopirdine (3 mg/kg) at the beginning of fluid resuscitation after haemorrhagic shock transiently reduced early fluid requirements in spontaneously breathing animals that were resuscitated for 3.5 hours. When mechanically ventilated rats were resuscitated after haemorrhagic shock with normal saline (NS) or with linopirdine-supplemented (10, 25 or 50 μg/mL) NS for 4.5 hours, linopirdine significantly and dose-dependently reduced fluid requirements by 14%, 45% and 55%, respectively. Lung and colon wet/dry weight ratios were reduced with linopirdine (25/50 μg/mL). There was no evidence for toxicity or adverse effects based on measurements of routine laboratory parameters and inflammation markers in plasma and tissue homogenates. Our findings support the concept that linopirdine-supplementation of resuscitation fluids is a safe and effective approach to reduce fluid requirements and tissue oedema formation during resuscitation from haemorrhagic shock.

Cardiovascular Responsiveness to Vasopressin and α1-Adrenergic Receptor Agonists After Burn Injury

The effects of burn injury on cardiovascular responsiveness to vasoactive agents are not well understood. The aims of this study were to determine whether burn injury alters cardiovascular reactivity to vasoactive drugs in vivo and intrinsic function of isolated mesenteric resistance arteries. Anesthetized Sprague-Dawley rats were subjected to sham procedure or 30% TBSA dorsal scald burn, followed by crystalloid resuscitation (Parkland Formula). At 24, 72, 96, and 168 hours post burn, rats were reanesthetized, and the mean arterial blood pressure (MAP) responses to various doses of the α1-adrenergic receptor agonist phenylephrine and arginine vasopressin were tested. Mesenteric arteries were harvested from uninjured animals and at 24 and 168 hours post burn. The responsiveness of arteries to phenylephrine and arginine vasopressin was tested by pressure myography. Dose response curves were generated and EC50 concentrations, Hill slopes, and maximal effects were compared. The potency of phenylephrine to increase MAP was reduced 2-fold 24 hours post burn (P < .05 vs sham) and gradually normalized at later time points. The reactivity of isolated arteries to phenylephrine was not significantly altered after burns. The potency of arginine vasopressin to increase MAP and to constrict isolated arteries was increased 2- to 3-fold at 24 hours post burn (P < .05) and normalized at later time points. Our findings suggest that burn injury differentially regulates vasopressor and blood pressure effects of α-adrenergic and vasopressin receptor agonists. Intrinsic vasopressin receptor reactivity of resistance arteries is sensitized early after burns. These findings will help to optimize resuscitation strategies and vasopressor use in difficult to resuscitate burn patients.

A Systematic Review of Neuroprotective Strategies during Hypovolemia and Hemorrhagic Shock

Severe trauma constitutes a major cause of death and disability, especially in younger patients. The cerebral autoregulatory capacity only protects the brain to a certain extent in states of hypovolemia; thereafter, neurological deficits and apoptosis occurs. We therefore set out to investigate neuroprotective strategies during haemorrhagic shock. This review was performed in accordance to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Before the start of the search, a review protocol was entered into the PROSPERO database. A systematic literature search of Pubmed, Web of Science and CENTRAL was performed in August 2017. Results were screened and evaluated by two researchers based on a previously prepared inclusion protocol. Risk of bias was determined by use of SYRCLE’s risk of bias tool. The retrieved results were qualitatively analysed. Of 9093 results, 119 were assessed in full-text form, 16 of them ultimately adhered to the inclusion criteria and were qualitatively analyzed. We identified three subsets of results: (1) hypothermia; (2) fluid therapy and/or vasopressors; and (3) other neuroprotective strategies (piracetam, NHE1-inhibition, aprotinin, human mesenchymal stem cells, remote ischemic preconditioning and sevoflurane). Overall, risk of bias according to SYRCLE’s tool was medium; generally, animal experimental models require more rigorous adherence to the reporting of bias-free study design (randomization, etc.). While the individual study results are promising, the retrieved neuroprotective strategies have to be evaluated within the current scientific context—by doing so, it becomes clear that specific promising neuroprotective strategies during states of haemorrhagic shock remain sparse. This important topic therefore requires more in-depth research.

Early and sustained vasopressin infusion augments the hemodynamic efficacy of restrictive fluid resuscitation and improves survival in a liver laceration model of hemorrhagic shock

BACKGROUND

Current management of hemorrhagic shock favors restrictive fluid resuscitation before control of the bleeding source. We investigated the additional effects of early and sustained vasopressin infusion in a swine model of hemorrhagic shock produced by liver laceration.

METHODS

Forty male domestic pigs (32-40 kg) had a liver laceration inflicted with an X-shaped blade clamp, 32 received a second laceration at minute 7.5, and 24 received two additional lacerations at minute 15. Using a two-by-two factorial design, animals were randomized 1:1 to receive vasopressin infusion (0.04 U/kg per minute) or vehicle intraosseously from minute 7 until minute 240 and 1:1 to receive isotonic sodium chloride solution (12 mL/kg) intravenously at minute 30 or no fluids.

RESULTS

Kaplan-Meier curves showed greater survival after vasopressin with isotonic sodium chloride solution (8/10) compared to vasopressin without isotonic sodium chloride solution (4/10), vehicle with isotonic sodium chloride solution (3/10), or vehicle without isotonic sodium chloride solution (3/10), but the differences were not statistically significant (p = 0.095 by log-rank test). However, logistic regression showed vasopressin to elicit a statistically significant benefit on survival (p = 0.042). Vasopressin augmented mean aortic pressure between 10 and 20 mm Hg without intensifying the rate of bleeding from liver laceration, which was virtually identical to that of vehicle-treated animals (33.9 ± 5.1 and 33.8 ± 4.8 mL/kg). Vasopressin increased systemic vascular resistance and reduced transcapillary fluid extravasation, augmenting the volume of isotonic sodium chloride solution retained (6.5 ± 2.7 vs 2.4 ± 2.0 mL/kg by minute 60). The cardiac output and blood flow to the myocardium, liver, spleen, kidney, small bowel, and skeletal muscle at minute 120 and minute 180 were comparable or higher in the vasopressin group.

CONCLUSIONS

Early and sustained vasopressin infusion provided critical hemodynamic stability during hemorrhagic shock induced by liver laceration and increased the hemodynamic efficacy of restrictive fluid resuscitation without intensifying bleeding or compromising organ blood flow resulting in improved 240-minute survival.

Kv7 voltage-activated potassium channel inhibitors reduce fluid resuscitation requirements after hemorrhagic shock in rats

Background

Recent evidence suggests that drugs targeting Kv7 channels could be used to modulate vascular function and blood pressure. Here, we studied whether Kv7 channel inhibitors can be utilized to stabilize hemodynamics and reduce resuscitation fluid requirements after hemorrhagic shock.

Methods

Anesthetized male Sprague-Dawley rats were instrumented with arterial and venous catheters for blood pressure monitoring, hemorrhage and fluid resuscitation. Series 1: Linopirdine (Kv7 channel blocker, 0.1–6 mg/kg) or retigabine (Kv7 channel activator, 0.1–12 mg/kg) were administered to normal animals. Series 2: Animals were hemorrhaged to a MAP of 25 mmHg for 30 min, followed by fluid resuscitation with normal saline (NS) to a MAP of 70 mmHg until t = 75 min. Animals were treated with single bolus injections of vehicle, linopirdine (1–6 mg/kg), XE-991 (structural analogue of linopirdine with higher potency for channel blockade, 1 mg/kg) prior to fluid resuscitation. Series 3: Animals were resuscitated with NS alone or NS supplemented with linopirdine (1.25–200 μg/mL). Data were analyzed with 2-way ANOVA/Bonferroni post-hoc testing.

Results

Series 1: Linopirdine transiently (10–15 min) and dose-dependently increased MAP by up to 15%. Retigabine dose-dependently reduced MAP by up to 60%, which could be reverted with linopirdine. Series 2: Fluid requirements to maintain MAP at 70 mmHg were 65 ± 34 mL/kg with vehicle, and 57 ± 13 mL/kg, 22 ± 8 mL/kg and 22 ± 11 mL/kg with intravenous bolus injection of 1, 3 and 6 mg/kg linopirdine, respectively. XE-991 (1 mg/kg), reduced resuscitation requirements comparable to 3 mg/kg linopirdine.

Series 3: When resuscitation was performed with linopirdine-supplemented normal saline (NS), fluid requirements to stabilize MAP were 73 ± 12 mL/kg with NS alone and 72 ± 24, 61 ± 20, 36 ± 9 and 31 ± 9 mL/kg with NS supplemented with 1.25, 6.25, 12.5 and 200 μg/mL linopirdine, respectively.

Conclusions

Our data suggest that Kv7 channel blockers could be used to stabilize blood pressure and reduce fluid resuscitation requirements after hemorrhagic shock.

Association Between Circulating Copeptin Level and Mortality Risk in Patients with Intracerebral Hemorrhage: a Systemic Review and Meta-Analysis

Copeptin has been identified as a biomarker of disease severity and is associated with mortality risk in several common diseases. This study sought to determine the association between circulating copeptin level and mortality risk in patients with intracerebral hemorrhage. PubMed, Web of Science, and Wanfang Medicine Database were searched for studies assessing the association between circulating copeptin level and mortality risk in patients with intracerebral hemorrhage. The pooled hazard ratio (HR) of mortality was calculated and presented with 95 % confidence interval (95 % CI). Data from 1332 intracerebral hemorrhage patients were derived from 9 studies. Meta-analysis showed that intracerebral hemorrhage patients with poor prognosis had much higher copeptin levels than those survivors (standardized mean difference = 1.68, 95 % CI 1.26-2.11, P < 0.00001). Meta-analysis of 8 studies with HRs showed that high circulating copeptin level was associated with higher risk of mortality in patients with intracerebral hemorrhage (HR = 2.42, 95 % CI 1.60-3.65, P < 0.0001). Meta-analysis of 6 studies with adjusted HRs showed that high circulating copeptin level was independently associated with higher risk of mortality in patients with intracerebral hemorrhage (HR = 1.67, 95 % CI 1.26-2.22, P = 0.0003). Our study suggests that there is an obvious association between circulating copeptin level and mortality in patients with intracerebral hemorrhage. High circulating copeptin level is independently associated with higher risk of mortality in patients with intracerebral hemorrhage.

Pharmacological targeting of chemokine (C-X-C motif) receptor 4 in porcine polytrauma and hemorrhage models

BACKGROUND

Recent evidence suggests that chemokine receptor CXCR4 regulates vascular α1-adrenergic receptor function and that the noncognate CXCR4 agonist ubiquitin has therapeutic potential after trauma/hemorrhage. Pharmacologic properties of ubiquitin in large animal trauma models, however, are poorly characterized. Thus, the aims of the present study were to determine the effects of CXCR4 modulation on resuscitation requirements after polytrauma, to assess whether ubiquitin influences survival times after lethal polytrauma-hemorrhage, and to characterize its dose-effect profile in porcine models.

METHODS

Anesthetized pigs underwent polytrauma (PT, femur fractures/lung contusion) alone (Series 1) or PT/hemorrhage (PT/H) to a mean arterial blood pressure of 30 mmHg with subsequent fluid resuscitation (Series 2 and 3) or 40% blood volume hemorrhage within 15 minutes followed by 2.5% blood volume hemorrhage every 15 minutes without fluid resuscitation (Series 4). In Series 1, ubiquitin (175 and 350 nmol/kg), AMD3100 (CXCR4 antagonist, 350 nmol/kg), or vehicle treatment 60 minutes after PT was performed. In Series 2, ubiquitin (175, 875, and 1,750 nmol/kg) or vehicle treatment 60 minutes after PT/H was performed. In Series 3, ubiquitin (175 and 875 nmol/kg) or vehicle treatment at 60 and 180 minutes after PT/H was performed. In Series 4, ubiquitin (875 nmol/kg) or vehicle treatment 30 minutes after hemorrhage was performed.

RESULTS

In Series 1, resuscitation fluid requirements were significantly reduced by 40% with 350-nmol/kg ubiquitin and increased by 25% with AMD3100. In Series 2, median survival time was 190 minutes with vehicle, 260 minutes with 175-nmol/kg ubiquitin, and longer than 420 minutes with 875-nmol/kg and 1,750-nmol/kg ubiquitin (p < 0.05 vs. vehicle). In Series 3, median survival time was 288 minutes with vehicle and 336 minutes and longer than 420 minutes (p < 0.05 vs. vehicle) with 175-nmol/kg and 875-nmol/kg ubiquitin, respectively. In Series 4, median survival time was 147.5 minutes and 150 minutes with vehicle and ubiquitin, respectively (p > 0.05).

CONCLUSION

These findings further suggest CXCR4 as a drug target after PT/H. Ubiquitin treatment reduces resuscitation fluid requirements and provides survival benefits after PT/H. The pharmacological effects of ubiquitin treatment occur dose dependently.

Vasopressin Infusion with Small-Volume Fluid Resuscitation during Hemorrhagic Shock Promotes Hemodynamic Stability and Survival in Swine

Introduction

Current management of hemorrhagic shock (HS) in the battlefield and civilian settings favors small-volume fluid resuscitation before controlling the source of bleeding. We investigated in a swine model of HS the effects of vasopressin infusion along with small-volume fluid resuscitation; with erythropoietin (EPO) and HS severity as additional factors.

Methods

HS was induced in 24 male domestic pigs (36 to 41 kg) by blood withdrawal (BW) through a right atrial cannula modeling spontaneous bleeding by a mono-exponential decay function. The initial 12 pigs received no fluids; the last 12 pigs received normal saline (NS) half the BW volume. Pigs were randomized 2:1 to receive intraosseously vasopressin (0.04 U/kg·min^-1) or vehicle control from minute 7 to minute 210. Pigs assigned to vasopressin were further randomized 1:1 to receive EPO (1,200 U/kg) or vehicle control and 1:1 to have 65% or 75% BW of their blood volume. Shed blood was reinfused at 210 minutes and the pigs recovered from anesthesia.

Results

Survival at 72 hours was influenced by vasopressin and NS but not by EPO or % BW. Vasopressin with NS promoted the highest survival (8/8) followed by vasopressin without NS (3/8), NS without vasopressin (1/4), and neither treatment (0/4) with overall statistical significance (log-rank test, p = 0.009) and each subset different from vasopressin with NS by Holm-Sidak test. Vasopressin increased systemic vascular resistance whereas NS increased cardiac output.

Conclusion

Vasopressin infusion with small-volume fluid resuscitation during severe HS was highly effective enabling critical hemodynamic stabilization and improved 72 hour survival.

Comparison of normal saline, hypertonic saline albumin and terlipressin plus hypertonic saline albumin in an infant animal model of hypovolemic shock

Introduction

In series of cases and animal models suffering hemorrhagic shock, the use of vasopressors has shown potential benefits regarding hemodynamics and tissue perfusion. Terlipressin is an analogue of vasopressin with a longer half-life that can be administered by bolus injection. We have previously observed that hypertonic albumin improves resuscitation following controlled hemorrhage in piglets. The aim of the present study was to analyze whether the treatment with the combination of terlipressin and hypertonic albumin can produce better hemodynamic and tissular perfusion parameters than normal saline or hypertonic albumin alone at early stages of hemorrhagic shock in an infant animal model.

Methods

Experimental, randomized animal study including 39 2-to-3-month-old piglets. Thirty minutes after controlled 30 ml/kg bleed, pigs were randomized to receive either normal saline (NS) 30 ml/kg (n = 13), 5% albumin plus 3% hypertonic saline (AHS) 15 ml/kg (n = 13) or single bolus of terlipressin 15 μg/kg i.v. plus 5% albumin plus 3% hypertonic saline 15 ml/kg (TAHS) (n = 13) over 30 minutes. Global hemodynamic and tissular perfusion parameters were compared.

Results

After controlled bleed a significant decrease of blood pressure, cardiac index, central venous saturation, carotid and peripheral blood flow, brain saturation and an increase of heart rate, gastric PCO₂ and lactate was observed. After treatment no significant differences in most hemodynamic (cardiac index, mean arterial pressure) and perfusion parameters (lactate, gastric PCO₂, brain saturation, cutaneous blood flow) were observed between the three therapeutic groups. AHS and TAHS produced higher increase in stroke volume index and carotid blood flow than NS.

Conclusions

In this pediatric animal model of hypovolemic shock, albumin plus hypertonic saline with or without terlipressin achieved similar hemodynamics and perfusion parameters than twice the volume of NS. Addition of terlipressin did not produce better results than AHS.

Effects of intraosseous erythropoietin during hemorrhagic shock in swine

Objective

To determine whether erythropoietin given during hemorrhagic shock (HS) ameliorates organ injury while improving resuscitation and survival.

Methods

Three series of 24 pigs each were studied. In an initial series, 50% of the blood volume (BV) was removed in 30 minutes and normal saline (threefold the blood removed) started at minute 90 infusing each third in 30, 60, and 150 minutes with shed blood reinfused at minute 330 (HS-50_BV). In a second series, the same HS-50_BV protocol was used but removing an additional 15% of BV from minute 30 to 60 (HS-65_BV). In a final series, blood was removed as in HS-65_BV and intraosseous vasopressin given from minute 30 (0.04 U/kg min⁻¹) until start of shed blood reinfusion at minute 150 (HS-65_BV+VP). Normal saline was reduced to half the blood removed and given from minute 90 to 120 in half of the animals. In each series, animals were randomized 1∶1 to receive erythropoietin (1,200 U/kg) or control solution intraosseously after removing 10% of the BV.

Results

In HS-50_BV, O₂ consumption remained near baseline yielding minimal lactate increases, 88% resuscitability, and 60% survival at 72 hours. In HS-65_BV, O₂ consumption was reduced and lactate increased yielding 25% resuscitability. In HS-65_BV+VP, vasopressin promoted hemodynamic stability yielding 92% resuscitability and 83% survival at 72 hours. Erythropoietin did not affect resuscitability or subsequent survival in any of the series but increased interleukin-10, attenuated lactate increases, and ameliorated organ injury based on lesser troponin I, AST, and ALT increases and lesser neurological deficits in the HS-65_BV+VP series.

Conclusions

Erythropoietin given during HS in swine failed to alter resuscitability and 72 hour survival regardless of HS severity and concomitant treatment with fluids and vasopressin but attenuated acute organ injury. The studies also showed the efficacy of vasopressin and restrictive fluid resuscitation for hemodynamic stabilization and survival.

Comparison of the performances of copeptin and multiple biomarkers in long-term prognosis of severe traumatic brain injury

Enhanced blood levels of copeptin correlate with poor clinical outcomes after acute critical illness. This study aimed to compare the prognostic performances of plasma concentrations of copeptin and other biomarkers like myelin basic protein, glial fibrillary astrocyte protein, S100B, neuron-specific enolase, phosphorylated axonal neurofilament subunit H, Tau and ubiquitin carboxyl-terminal hydrolase L1 in severe traumatic brain injury. We recruited 102 healthy controls and 102 acute patients with severe traumatic brain injury. Plasma concentrations of these biomarkers were determined using enzyme-linked immunosorbent assay. Their prognostic predictive performances of 6-month mortality and unfavorable outcome (Glasgow Outcome Scale score of 1-3) were compared. Plasma concentrations of these biomarkers were statistically significantly higher in all patients than in healthy controls, in non-survivors than in survivors and in patients with unfavorable outcome than with favorable outcome. Areas under receiver operating characteristic curves of plasma concentrations of these biomarkers were similar to those of Glasgow Coma Scale score for prognostic prediction. Except plasma copeptin concentration, other biomarkers concentrations in plasma did not statistically significantly improve prognostic predictive value of Glasgow Coma Scale score. Copeptin levels may be a useful tool to predict long-term clinical outcomes after severe traumatic brain injury and have a potential to assist clinicians.

Plasma copeptin level predicts acute traumatic coagulopathy and progressive hemorrhagic injury after traumatic brain injury

Higher plasma copeptin levels correlate with poor clinical outcomes after traumatic brain injury. Nevertheless, their links with acute traumatic coagulopathy and progressive hemorrhagic injury are unknown. Therefore, we aimed to investigate the relationship between plasma copeptin levels, acute traumatic coagulopathy and progressive hemorrhagic injury in patients with severe traumatic brain injury. We prospectively studied 100 consecutive patients presenting within 6h from head trauma. Progressive hemorrhagic injury was present when the follow-up computerized tomography scan reported any increase in size or number of the hemorrhagic lesion, including newly developed ones. Acute traumatic coagulopathy was defined as an activated partial thromboplastic time greater than 40s and/or international normalized ratio greater than 1.2 and/or a platelet count less than 120×10(9)/L. We measured plasma copeptin levels on admission using an enzyme-linked immunosorbent assay in a blinded fashion. In multivariate logistic regression analysis, plasma copeptin level emerged as an independent predictor of progressive hemorrhagic injury and acute traumatic coagulopathy. Using receiver operating characteristic curves, we calculated areas under the curve for progressive hemorrhagic injury and acute traumatic coagulopathy. The predictive performance of copeptin was similar to that of Glasgow Coma Scale score. However, copeptin did not obviously improve the predictive value of Glasgow Coma Scale score. Thus, copeptin may help in the prediction of progressive hemorrhagic injury and acute traumatic coagulopathy after traumatic brain injury.

Modern resuscitation of hemorrhagic shock: what is on the horizon?

PURPOSE

Mortality rates among the severely injured remain high. The successful treatment of hemorrhagic shock relies on expeditious control of bleeding through surgical ligation, packing, or endovascular techniques. An important secondary concern in hemorrhaging patients is how to respond to the lost blood volume. A single method that is able to adequately address all needs of the exsanguinating patient has not yet been agreed upon, despite a large growth of knowledge regarding the causative factors of traumatic shock.

METHODS

A review of relevent literature was performed.

CONCLUSIONS

Many different trials are currently underway to discriminate ways to improve outcomes in the severely injured and bleeding patient.  This paper will review: (1) recent advances in our understanding of the effects hemorrhagic shock has on the coagulation cascade and vascular endothelium, (2) recent research findings that have changed resuscitation, and (3) resuscitation strategies that are not widely used but under active investigation.

Trauma-Related Critical Care

BACKGROUND

Post-trauma resuscitation has evolved based on civilian and wartime experiences over the last decade. Similarly, data from large multicenter randomized trials have changed the management of critically ill trauma patients in the intensive care unit.

METHODS

This is a review of the literature focusing on areas relevant to the management of trauma patients in the intensive care unit.

RESULTS

The following topics are included: (1) ventilator management, (2) trauma sepsis, (3) use of vasopressors in hemorrhage, (4) glucose control, (5) nutrition, and (6) hemodynamic monitoring.

CONCLUSION

This review demonstrated the most recent data of trauma-related critical care. Further studies will be needed to settle growing controversies in the management of critically injured patients.

Renal vasoconstriction by vasopressin V1a receptors is modulated by nitric oxide, prostanoids, and superoxide but not the ADP ribosyl cyclase CD38

Renal blood flow (RBF) responses to arginine vasopressin (AVP) were tested in anesthetized wild-type (WT) and CD38(-/-) mice that lack the major calcium-mobilizing second messenger cyclic ADP ribose. AVP (3-25 ng) injected intravenously produced dose-dependent decreases in RBF, reaching a maximum of 25 ± 2% below basal RBF in WT and 27 ± 2% in CD38(-/-) mice with 25 ng of AVP. Renal vascular resistance (RVR) increased 75 ± 6% and 78 ± 6% in WT and CD38(-/-) mice. Inhibition of nitric oxide (NO) synthase with nitro-L-arginine methyl ester (L-NAME) increased the maximum RVR response to AVP to 308 ± 76% in WT and 388 ± 81% in CD38(-/-) (P < 0.001 for both). Cyclooxygenase inhibition with indomethacin increased the maximum RVR response to 125 ± 15% in WT and 120 ± 14% in CD38(-/-) mice (P < 0.001, <0.05). Superoxide suppression with tempol inhibited the maximum RVR response to AVP by 38% in both strains (P < 0.005) but was ineffective when administered after L-NAME. The rate of RBF recovery (relaxation) after AVP was slowed by L-NAME and indomethacin (P < 0.001, <0.005) but was unchanged by tempol. All vascular responses to AVP were abolished by an AVP V1a receptor antagonist. A V2 receptor agonist or antagonist had no effect on AVP-induced renal vasoconstriction. Taken together, the results indicate that renal vasoconstriction by AVP in the mouse is strongly buffered by vasodilatory actions of NO and prostanoids. The vasoconstriction depends on V1a receptor activation without involvement of CD38 or concomitant vasodilatation by V2 receptors. The role of superoxide is to enhance the contractile response to AVP, most likely by reducing the availability of NO rather than directly stimulating intracellular contraction signaling pathways.

Autonomous device for application in late-phase hemorrhagic shock prevention

Hemorrhagic shock (HS) is the leading cause of death for people with traumatic injuries. The onset of HS is correlated with marked changes in the plasma vasopressin levels and some studies indicate that administrating vasopressin in the bloodstream can help stabilize the situation. This situation calls naturally for the use of implantable devices for both the monitoring and treatment of HS. In this work, we present a self-powered hemorrhagic-shock autonomous integrated device (hemoAID) that continuously monitors vasopressin levels and releases vasopressin automatically when levels drop below a certain threshold. We demonstrate that the device can operate at physiological concentrations of vasopressin, in sheep serum, thus paving the way towards the development of an autonomous implantable device for HS prevention.

Resuscitation in a multiple casualty event

A major weakness in the emergency medical response to multiple casualty events continues to be the resuscitation component, which should consist of the systematic application of basic, advanced, and prolonged life support and definitive care within 24 hours. There have been major advances in emergency medical care over the last decade, including the feasibility of point-of-care ultrasound to aid in rapid assessment of injuries in the field, damage control resuscitation, and resuscitative surgery protocols, delivered by small trauma/resuscitation teams equipped with regional anesthesia capability for rapid deployment. Widespread adoption of these best practices may improve the delivery of resuscitative care in future multiple casualty events.