Effect of blood pressure on hemorrhage volume and survival in a near-fatal hemorrhage model incorporating a vascular injury

Influence of blood hemodynamics on the treatment outcomes of limited fluid resuscitation in emergency patients with traumatic hemorrhagic shock

OBJECTIVES

Traumatic hemorrhagic shock is a major death-related factor contributing to mortality in emergencies and can be effectively handled by the Limited Fluid Resuscitation (LFR) method. In the current investigation, the authors analyzed the influence of different administrating blood pressure on the treatment outcomes of LFR.

METHODS

276 participants were enrolled in the current study retrospectively from January 2016 to December 2021 and were divided into three groups based on the administrating blood pressure of LFR. The difference among the three groups regarding serum levels of cytokines as well as blood hemodynamics parameters was analyzed.

RESULTS

The results showed after the T2 stage treatment, cytokine levels in the three groups were all significantly influenced by different LFR strategies with medium MAP showing the strongest effects on the expression of all cytokine genes. Moreover, the MAP value was in positive correlation with IL-6, IL-10, and TNF-α levels, but showed no clear relation with IL-4 level in all three groups. Regarding the effects on hemodynamics parameters, the levels of CVP, CO, and CI were slightly increased by the different LFR administrating strategies, and the effect of medium and high MAP was statistically stronger than that of low MAP.

CONCLUSION

The present results showed that LFR would influence serum inflammatory levels by improving blood hemodynamics parameters. Medium MAP showed the strongest improving effects with the least side effects, which can be employed as the optimal administrating strategy for LFR in the future.

The effect of restrictive fluid management on outcomes among geriatric hip fractures: a retrospective cohort study at five level I trauma centers

Restrictive fluid management (RFM) for hemodynamically unstable trauma patients has reduced mortality rates. The objective was to determine whether RFM benefits geriatric hip fracture patients, who are usually hemodynamically stable.

Design

Retrospective propensity-matched study.

Setting

Five Level I trauma centers (January 1, 2018-December 12, 2018).

Patients

Geriatric patients (65 years or older) with hip fractures were included in this study. Patients with multiple injuries, nonoperative management, and preoperative blood products were excluded.

Intervention

Patients were grouped by fluid volume (normal saline, lactated Ringer, dextrose, electrolytes, and medications) received preoperatively or ≤24 hours of arrival; patients with standard fluid management (SFM) received ≥150 mL and RFM <150 mL of fluids.

Main Outcome Measurements

The primary outcomes were length of stay (LOS), delayed ambulation (>2 days postoperatively), and mortality. Paired Student t-tests, Wilcoxon paired rank sum tests, and McNemar tests were used; an α value of < 0.05 was considered statistically significant.

Results

There were 523 patients (40% RFM, 60% SFM); after matching, there were 95 patients per arm. The matched patients were well-balanced, including no difference in time from arrival to surgery. RFM and SFM patients received a median of 80 mL and 1250 mL of preoperative fluids, respectively (P < 0.001). Postoperative fluid volumes were 1550 versus 2000 mL, respectively, (P = 0.73), and LOSs were similar between the two groups (5 versus 5 days, P = 0.83). Mortality and complications, including acute kidney injuries, were similar. Delayed ambulation rates were similar overall. When stratified by preinjury ambulation status, SFM was associated with delayed ambulation for patients not walking independently before injury (P = 0.01), but RFM was not (P = 0.09).

Conclusions

RFM seems to be safe in terms of laboratory results, complications, and disposition. SFM may lead to delayed ambulation for patients who are not walking independently before injury.

Five Decades of Trauma Anesthesiology

We present a brief history of the scientific and educational development of trauma anesthesiology. Key milestones from the past 50 years are noted, as well as the current standing of the subspecialty and prospects for the future.

A physiology-based trigger score to guide perioperative transfusion of allogeneic red blood cells: A multicentre randomised controlled trial

BACKGROUND

Restrictive blood transfusion is recommended by major guidelines for perioperative management, but requires objective assessment at 7-10 g/dl haemoglobin (Hb). A scoring system that considers the physiological needs of the heart may simply the practice and reduce transfusion.

METHODS

Patients (14-65 years of age) undergoing non-cardiac surgery were randomised at a 1:1 ratio to a control group versus a Perioperative Transfusion Trigger Score (POTTS) group. POTTS (maximum of 10) was calculated as 6 plus the following: adrenaline infusion rate (0 for no infusion, 1 for ≤0.05 μg·kg^-1 ·min^-1 , and 2 for higher rate), FiO₂ to keep SpO₂ at ≥95% (0 for ≤35%, 1 for 36%-50%, and 2 for higher), core temperature (0 for <38°C, 1 for 38-40°C, and 2 for higher), and angina history (0 for no, 1 for exertional, and 2 for resting). Transfusion is indicated when actual Hb is lower than the calculated POTTS in individual patients. Transfusion in the control group was based on the 2012 American Association for Blood Banks (AABB) guideline. The primary outcome was the proportion of the patients requiring transfusion of allogeneic red blood cells (RBCs) during the perioperative period (until discharge from hospital), as assessed in the intention-to-treat (ITT) population (all randomised subjects).

RESULT

A total of 864 patients (mean age 44.4 years, 244 men and 620 women) were enrolled from December 2017 to January 2021 (433 in the control and 431 in the POTTS group). Baseline Hb was 9.2 ± 1.8 and 9.2 ± 1.7 g/dl in the control and POTTS groups, respectively. In the ITT analysis, the proportion of the patients receiving allogeneic RBCs was 43.9% (190/433) in the control group versus 36.9% (159/431) in the POTTS group (p = 0.036). Lower rate of allogeneic RBCs transfusion in the POTTS group was also evident in the per-protocol analysis (42.8% vs. 35.5%, p = 0.030). Transfusion volume was 4.0 (2.0, 6.0) and 3.5 (2.0, 5.5) units (200 ml/unit) in the control and POTTS groups, respectively (p = 0.25). The rate of severe postoperative complications (Clavien-Dindo grade IIIa and higher) was 3.9% in the control group versus 1.2% in the POTTS group (p = 0.010).

CONCLUSION

Transfusion of allogeneic RBCs based on the POTTS was safe and reduced the transfusion requirement in patients undergoing non-cardiac surgery.

Heart rate and diastolic arterial pressure in cardiac arrest patients: A nationwide, multicenter prospective registry

Background

Guidelines have recommended monitoring mean arterial pressure (MAP) and systolic arterial pressure (SAP) in cardiac arrest patients, but there has been relatively little regard for diastolic arterial pressure (DAP) and heart rate (HR). We aimed to determine the prognostic significance of hemodynamic parameters at all time points during targeted temperature management (TTM).

Methods

We reviewed the SAP, DAP, MAP, and HR data in out-of-hospital cardiac arrest (OHCA) survivors from the prospective multicenter registry of 22 teaching hospitals. This study included 1371 patients who underwent TTM among 10,258 cardiac arrest patients. The hemodynamic parameters were recorded every 6 hours from the return of spontaneous circulation (ROSC) to 4 days. The risks of those according to time points during TTM were compared.

Results

Of the included patients, 943 (68.8%) had poor neurological outcomes. The predictive ability of DAP surpassed that of SAP and MAP at all time points, and among the hemodynamic variables HR/DAP was the best predictor of the poor outcome. The risks in patients with DAP < 55 to 70 mmHg and HR > 70 to 100 beats/min were steeply increased for 2 days after ROSC and correlated with the poor outcome at all time points. Bradycardia showed lower risks only at 6 hours to 24 hours after ROSC.

Conclusion

Hemodynamic parameters should be intensively monitored especially for 2 days after ROSC because cardiac arrest patients may be vulnerable to hemodynamic instability during TTM. Monitoring HR/DAP can help access the risks in cardiac arrest patients.

A Multifunctional, Low-Volume Resuscitation Cocktail Improves Vital Organ Blood Flow and Hemostasis in a Pig Model of Polytrauma with Traumatic Brain Injury

The resuscitation of polytrauma with hemorrhagic shock and traumatic brain injury (TBI) is a balance between permissive hypotension and maintaining vital organ perfusion. There is no current optimal solution. This study tested whether a multifunctional resuscitation cocktail supporting hemostasis and perfusion could mitigate blood loss while improving vital organ blood flow during prolonged limited resuscitation. Anesthetized Yorkshire swine were subjected to fluid percussion TBI, femur fracture, catheter hemorrhage, and aortic tear. Fluid resuscitation was started when lactate concentration reached 3–4 mmol/L. Animals were randomized to one of five groups. All groups received hydroxyethyl starch solution and vasopressin. Low- and high-dose fibrinogen (FBG) groups additionally received 100 and 200 mg/kg FBG, respectively. A third group received TXA and low-dose FBG. Two control groups received albumin, with one also including TXA. Animals were monitored for up to 6 h. Blood loss was decreased and vital organ blood flow was improved with low- and high-dose fibrinogen compared to albumin controls, but survival was not improved. There was no additional benefit of high- vs. low-dose FBG on blood loss or survival. TXA alone decreased blood loss but had no effect on survival, and combining TXA with FBG provided no additional benefit. Pooled analysis of all groups containing fibrinogen vs. albumin controls found improved survival, decreased blood loss, and improved vital organ blood flow with fibrinogen delivery. In conclusion, a low-volume resuscitation cocktail consisting of hydroxyethyl starch, vasopressin, and fibrinogen concentrate improved outcomes compare to controls during limited resuscitation of polytrauma.

Management of Patient with Simultaneous Overt Gastrointestinal Bleeding and Myocardial Infarction with ST-Segment Elevation - Priority Endoscopy

Background

The current ERC guidelines are the source of many positive changes, reduction of mortality, length of hospitalization and improvement of prognosis of STEMI patients. However, there is a small group of patients whose slight modification in guidelines would further reduce in-hospital mortality and hospitalization costs. These are patients with concomitant STEMI infarction and gastrointestinal bleeding.

Methods

Two separate methods of treatment were compared in patients with concomitant gastrointestinal bleeding and ST-segment elevation myocardial infarction. The first – traditional approach, in the line with the ESC guidelines, the second innovative, with priority for endoscopy.

Results

Despite the innovative approach, the patient with endoscopy before PCI was discharged without complication. A patient who has undergone coronary intervention and who has been started on typical antiplatelet therapy prior to gastroenterological diagnosis has died due to massive bleeding.

Conclusion

For ethical reasons and in connection with the cardiological guidelines of the management of ACS, a study of patients with ASC a high risk of intestinal bleeding, in which endoscopy will have priority, and only later PCI, will probably never be performed. Although, as the described case shows, despite exceeding the 90 minutes time to implement PCI (<120 minutes) in logistic terms such behavior is completely feasible.

Is restrictive fluid resuscitation beneficial not only for hemorrhagic shock but also for septic shock?: A meta-analysis

BACKGROUND

Whether to use limited fluid resuscitation (LFR) in patients with hemorrhagic shock or septic shock remains controversial. This research was aimed to assess the pros and cons of utilizing LFR in hemorrhagic shock or septic shock patients.

METHODS

PubMed, Cochrane Library, Embase, Web of science, CNKI, VIP, and Wan Fang database searches included for articles published before December 15, 2020. Randomized controlled trials of LFR or adequate fluid resuscitation in hemorrhagic shock or septic shock patients were selected.

RESULT

This meta-analysis including 28 randomized controlled trials (RCTs) and registered 3288 patients. The 7 of 27 RCTs were the patients with septic shock. Others were traumatic hemorrhagic shock patients. Comparing LFR or adequate fluid resuscitation in hemorrhagic shock or septic shock patients, the summary odds ratio (OR) was 0.50 (95% confidence interval [CI] 0.42-0.60, P < .00001) for mortality, 0.46 (95% CI 0.31-0.70, P = .0002) for multiple organ dysfunction syndrome (MODS), 0.35 (95% CI 0.25-0.47) for acute respiratory distress syndrome (ARDS), and 0.33 (95% CI 0.20-0.56) for disseminated intravascular coagulation (DIC).

CONCLUSION

Limited fluid resuscitation is the benefit of both traumatic hemorrhagic shock patients and septic shock patients.

Iatrogenic vascular laceration during posterior lumbar disc surgery: a literature review

Iatrogenic vascular laceration is a rare but well-known complication of posterior lumbar disc surgery (PLUDS). We performed a review of the literature to evaluate the management of this life-threatening complication. A total of 54 papers containing 100 cases of vascular laceration following PLUDS between 1969 and 2018 were analyzed with our representative case with a left common iliac artery (CIA) laceration during a posterior approach for a far lateral L4-L5 disc herniation. There were 54 females and 35 males (12 cases with unreported gender) with ages ranging from 20 to 72 years. The most commonly involved spinal level was L4-L5 (n = 67). The duration from the causative surgery to the symptom of the vascular injury ranged from 0 to 50 h (mean, 7.3 h). Only 47.3% of patients underwent postoperative imaging and the most commonly injured vessel was the CIA (n = 49). Vascular repair, open surgery, and/or an endovascular procedure was performed in 95 patients. The most frequent complications were deep venous thrombosis in the leg and pulmonary emboli, where a complete recovery was seen in 75.3% of patients. The mortality rate was 18.8%. In hemodynamically unstable cases, an emergent exploratory laparotomy was life-saving even without vascular imaging, although angiography with/without endovascular intervention may be used in stable patients.

Diastolic shock index and clinical outcomes in patients with septic shock

Background

Loss of vascular tone is a key pathophysiological feature of septic shock. Combination of gradual diastolic hypotension and tachycardia could reflect more serious vasodilatory conditions. We sought to evaluate the relationships between heart rate (HR) to diastolic arterial pressure (DAP) ratios and clinical outcomes during early phases of septic shock.

Methods

Diastolic shock index (DSI) was defined as the ratio between HR and DAP. DSI calculated just before starting vasopressors (Pre-VPs/DSI) in a preliminary cohort of 337 patients with septic shock (January 2015 to February 2017) and at vasopressor start (VPs/DSI) in 424 patients with septic shock included in a recent randomized controlled trial (ANDROMEDA-SHOCK; March 2017 to April 2018) was partitioned into five quantiles to estimate the relative risks (RR) of death with respect to the mean risk of each population (assumed to be 1). Matched HR and DAP subsamples were created to evaluate the effect of the individual components of the DSI on RRs. In addition, time-course of DSI and interaction between DSI and vasopressor dose (DSI*NE.dose) were compared between survivors and non-survivors from both populations, while ROC curves were used to identify variables predicting mortality. Finally, as exploratory observation, effect of early start of vasopressors was evaluated at each Pre-VPs/DSI quintile from the preliminary cohort.

Results

Risk of death progressively increased at gradual increments of Pre-VPs/DSI or VPs/DSI (One-way ANOVA, p < 0.001). Progressive DAP decrease or HR increase was associated with higher mortality risks only when DSI concomitantly increased. Areas under the ROC curve for Pre-VPs/DSI, SOFA and initial lactate were similar, while mean arterial pressure and systolic shock index showed poor performances to predict mortality. Time-course of DSI and DSI*NE.dose was significantly higher in non-survivors from both populations (repeated-measures ANOVA, p < 0.001). Very early start of vasopressors exhibited an apparent benefit at higher Pre-VPs/DSI quintile.

Conclusions

DSI at pre-vasopressor and vasopressor start points might represent a very early identifier of patients at high risk of death. Isolated DAP or HR values do not clearly identify such risk. Usefulness of DSI to trigger or to direct therapeutic interventions in early resuscitation of septic shock need to be addressed in future studies.

Management of Nonvariceal Upper Gastrointestinal Bleeding: Guideline Recommendations From the International Consensus Group

DESCRIPTION

This update of the 2010 International Consensus Recommendations on the Management of Patients With Nonvariceal Upper Gastrointestinal Bleeding (UGIB) refines previous important statements and presents new clinically relevant recommendations.

METHODS

An international multidisciplinary group of experts developed the recommendations. Data sources included evidence summarized in previous recommendations, as well as systematic reviews and trials identified from a series of literature searches of several electronic bibliographic databases from inception to April 2018. Using an iterative process, group members formulated key questions. Two methodologists prepared evidence profiles and assessed quality (certainty) of evidence relevant to the key questions according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. Group members reviewed the evidence profiles and, using a consensus process, voted on recommendations and determined the strength of recommendations as strong or conditional.

RECOMMENDATIONS

Preendoscopic management: The group suggests using a Glasgow Blatchford score of 1 or less to identify patients at very low risk for rebleeding, who may not require hospitalization. In patients without cardiovascular disease, the suggested hemoglobin threshold for blood transfusion is less than 80 g/L, with a higher threshold for those with cardiovascular disease. Endoscopic management: The group suggests that patients with acute UGIB undergo endoscopy within 24 hours of presentation. Thermocoagulation and sclerosant injection are recommended, and clips are suggested, for endoscopic therapy in patients with high-risk stigmata. Use of TC-325 (hemostatic powder) was suggested as temporizing therapy, but not as sole treatment, in patients with actively bleeding ulcers. Pharmacologic management: The group recommends that patients with bleeding ulcers with high-risk stigmata who have had successful endoscopic therapy receive high-dose proton-pump inhibitor (PPI) therapy (intravenous loading dose followed by continuous infusion) for 3 days. For these high-risk patients, continued oral PPI therapy is suggested twice daily through 14 days, then once daily for a total duration that depends on the nature of the bleeding lesion. Secondary prophylaxis: The group suggests PPI therapy for patients with previous ulcer bleeding who require antiplatelet or anticoagulant therapy for cardiovascular prophylaxis.

Sagas of the Solanaceae: Speculative ethnobotanical perspectives on the Norse berserkers

ETHNOPHARMACOLOGICAL RELEVANCE

The Norse berserkers were wild warriors of Scandinavia known to enter a trance-like state that allowed them to fight with increased strength and a rage that granted them immunity to many forms of harm in battle. Though many theories have been advanced as to the cause of this state, the most widely believed is that the intoxicating mushroom Amanita muscaria was used.

AIM OF THE STUDY

The following article underlines the issues with this theory and provides an alternate intoxicant that fits with the reports of berserker behaviour much better: Hyoscyamus niger.

MATERIALS AND METHODS

Literature from a variety of disciplines pertaining to history, toxicology, pharmacology, and botany was compiled to frame and support the argument.

RESULTS

H. niger proved to be a more likely intoxicant used to induce the berserker rage state.

CONCLUSIONS

With its anticholinergic tropane alkaloids and symptom profile, H. niger is a much more likely cause of the berserker state than A muscaria. Though there is not enough archaeological and historical evidence to prove or disprove this theory, it provides a novel explanation that is at present the most viable means of understanding the berserkers' trance.

Higher Concentration of Hypertonic Saline Shows Better Recovery Effects on Rabbits with Uncontrolled Hemorrhagic Shock

Background

Our previous study found a novel fluid combination with better resuscitation effects under hypotensive condition at the early stage of uncontrolled hemorrhagic shock (UHS). However, the optimal recovery concentration of hypertonic saline in this fluid combination remains unknown. This experiment aimed to explore the optimal concentration.

Material/Methods

New Zealand white rabbits (n=40) were randomly divided into 5 groups, including a sham-operated group (SO), a shock non-treated group (SNT), a normal saline group (NS), and hypertonic saline groups (4.5% and 7.5%). We established an UHS model and administered various fluid combinations (dose-related sodium chloride solution+crystal-colloidal solution) to the groups followed by monitoring indexes of hemodynamic and renal function, measuring infusion volume and blood loss, and analyzing pathological morphology by hematoxylin and eosin staining.

Results

The hypertonic saline groups showed more stable hemodynamic indexes, reduced blood loss, fewer required infusions, and milder decreases in renal function than those of control groups (SNT and NS groups), and exhibited fewer pathological changes in the heart, lung, kidney, and liver. All indexes in the 4.5% and 7.5% groups were better than those of the NS group, and the hemodynamic indexes in the 7.5% group were more stable than those of the 4.5% group (P<0.05), with reduced blood loss and infusion volume and a milder decrease in renal function.

Conclusions

The novel fluid combination with 7.5% hypertonic saline group had a better recovery effect at the early stage of UHS before hemostasis compared to that of the 4.5% hypertonic saline group. This result may provide guidance for clinical fluid resuscitation.

Pre-hospital emergency medicine and the trauma intensive care unit

The system of trauma care has been revolutionised over the last decade with the introduction of major trauma networks across the United Kingdom and the development of subspecialist national training in pre-hospital emergency medicine. Pre-hospital care providers feed trauma patients into trauma units or major trauma centres depending upon the severity of their injuries and their stability for a potentially longer primary transfer to access specialist major trauma services. Trauma services are continually adapting and improving with the introduction of more advanced techniques into the pre-hospital arena are on the horizon, enabling trauma patients to receive more specialised treatment from medical professionals earlier after injury; this article will discuss some of the recent developments within pre-hospital emergency medicine, in-hospital trauma care and on into the intensive care unit, and how this has led to improved outcomes.

Trauma Hemostasis and Oxygenation Research Network position paper on the role of hypotensive resuscitation as part of remote damage control resuscitation

The Trauma Hemostasis and Oxygenation Research (THOR) Network has developed a consensus statement on the role of permissive hypotension in remote damage control resuscitation (RDCR). A summary of the evidence on permissive hypotension follows the THOR Network position on the topic. In RDCR, the burden of time in the care of the patients suffering from noncompressible hemorrhage affects outcomes. Despite the lack of published evidence, and based on clinical experience and expertise, it is the THOR Network's opinion that the increase in prehospital time leads to an increased burden of shock, which poses a greater risk to the patient than the risk of rebleeding due to slightly increased blood pressure, especially when blood products are available as part of prehospital resuscitation.The THOR Network's consensus statement is, "In a casualty with life-threatening hemorrhage, shock should be reversed as soon as possible using a blood-based HR fluid. Whole blood is preferred to blood components. As a part of this HR, the initial systolic blood pressure target should be 100 mm Hg. In RDCR, it is vital for higher echelon care providers to receive a casualty with sufficient physiologic reserve to survive definitive surgical hemostasis and aggressive resuscitation. The combined use of blood-based resuscitation and limiting systolic blood pressure is believed to be effective in promoting hemostasis and reversing shock".

Damage Control Resuscitation

Damage control surgery is a combination of temporizing surgical interventions to arrest hemorrhage and control infectious source, with goal directed resuscitation to restore normal physiology. The convention of damage control surgery largely arose following the discovery of the lethal triad of hypothermia, acidosis, and coagulopathy, with the goal of Damage Control Surgery (DCS) is to avoid the initiation of this "bloody vicious cycle" or to reverse its progression. While hypothermia and acidosis are generally corrected with resuscitation, coagulopathy remains a challenging aspect of DCS, and is exacerbated by excessive crystalloid administration. This chapter focuses on resuscitative principles in the four settings of trauma care: the prehospital setting, emergency department, operating room, and intensive care unit including historical perspectives, resuscitative methods, controversies, and future directions. Each setting provides unique challenges with specific goals of care.

Fluid Resuscitation in Tactical Combat Casualty Care: Yesterday and Today

The prevailing wisdom for the prehospital fluid resuscitation of trauma victims in hemorrhagic shock in 1992 was to administer 2 L of crystalloid solution as rapidly as possible. A review of the fluid resuscitation literature found that this recommendation was not well supported by the evidence at the time. Prehospital fluid resuscitation strategies were reevaluated in the 1993-1996 Tactical Combat Casualty Care (TCCC) research program. This article reviews the advances in prehospital fluid resuscitation as recommended by the original TCCC Guidelines and modified over the following 2 decades. These advances include hypotensive resuscitation, use of prehospital whole blood or blood components when feasible, and use of Hextend or selected crystalloids when logistical considerations make blood or blood component use not feasible.

Adjuncts to Resuscitation

Damage control resuscitation has been increasingly adopted and practiced over the last decade. The concepts used are not new to this era of medicine but are novel in combination. This chapter will focus on adjuncts to damage control resuscitation (DCR) including massive transfusion protocols, the “other” tenets of damage control resuscitation, hypertonic saline, tranexamic acid, pharmacologic resuscitation, Factor VIIa, and prothrombin complex, and viscoelastic testing.

The Evolving Science of Trauma Resuscitation

This review summarizes the evolution of trauma resuscitation from a one-size-fits-all approach to one tailored to patient physiology. The most dramatic change is in the management of actively bleeding patients, with a balanced blood product-based resuscitation approach (avoiding crystalloids) and surgery focused on hemorrhage control, not definitive care. When hemostasis has been achieved, definitive resuscitation to restore organ perfusion is initiated. This approach is associated with decreased mortality, reduced duration of stay, improved coagulation profile, and reduced crystalloid/vasopressor use. This article focuses on the tools and methods used for trauma resuscitation in the acute phase of trauma care.

Closed-Loop- and Decision-Assist-Guided Fluid Therapy of Human Hemorrhage

OBJECTIVES

We sought to evaluate the efficacy, efficiency, and physiologic consequences of automated, endpoint-directed resuscitation systems and compare them to formula-based bolus resuscitation.

DESIGN

Experimental human hemorrhage and resuscitation.

SETTING

Clinical research laboratory.

SUBJECTS

Healthy volunteers.

INTERVENTIONS

Subjects (n = 7) were subjected to hemorrhage and underwent a randomized fluid resuscitation scheme on separate visits 1) formula-based bolus resuscitation; 2) semiautonomous (decision assist) fluid administration; and 3) fully autonomous (closed loop) resuscitation. Hemodynamic variables, volume shifts, fluid balance, and cardiac function were monitored during hemorrhage and resuscitation. Treatment modalities were compared based on resuscitation efficacy and efficiency.

MEASUREMENTS AND MAIN RESULTS

All approaches achieved target blood pressure by 60 minutes. Following hemorrhage, the total amount of infused fluid (bolus resuscitation: 30 mL/kg, decision assist: 5.6 ± 3 mL/kg, closed loop: 4.2 ± 2 mL/kg; p < 0.001), plasma volume, extravascular volume (bolus resuscitation: 17 ± 4 mL/kg, decision assist: 3 ± 1 mL/kg, closed loop: -0.3 ± 0.3 mL/kg; p < 0.001), body weight, and urinary output remained stable under decision assist and closed loop and were significantly increased under bolus resuscitation. Mean arterial pressure initially decreased further under bolus resuscitation (-10 mm Hg; p < 0.001) and was lower under bolus resuscitation than closed loop at 20 minutes (bolus resuscitation: 57 ± 2 mm Hg, closed loop: 69 ± 4 mm Hg; p = 0.036). Colloid osmotic pressure (bolus resuscitation: 19.3 ± 2 mm Hg, decision assist, closed loop: 24 ± 0.4 mm Hg; p < 0.05) and hemoglobin concentration were significantly decreased after bolus fluid administration.

CONCLUSIONS

We define efficacy of decision-assist and closed-loop resuscitation in human hemorrhage. In comparison with formula-based bolus resuscitation, both semiautonomous and autonomous approaches were more efficient in goal-directed resuscitation of hemorrhage. They provide favorable conditions for the avoidance of over-resuscitation and its adverse clinical sequelae. Decision-assist and closed-loop resuscitation algorithms are promising technological solutions for constrained environments and areas of limited resources.

Permissive hypotension/hypotensive resuscitation and restricted/controlled resuscitation in patients with severe trauma

Achieving a balance between organ perfusion and hemostasis is critical for optimal fluid resuscitation in patients with severe trauma. The concept of “permissive hypotension” refers to managing trauma patients by restricting the amount of resuscitation fluid and maintaining blood pressure in the lower than normal range if there is continuing bleeding during the acute period of injury. This treatment approach may avoid the adverse effects of early, high-dose fluid resuscitation, such as dilutional coagulopathy and acceleration of hemorrhage, but does carry the potential risk of tissue hypoperfusion. Current clinical guidelines recommend the use of permissive hypotension and controlled resuscitation. However, it is not mentioned which subjects would receive most benefit from this approach, when considering factors such as age, injury mechanism, setting, or the presence or absence of hypotension. Recently, two randomized clinical trials examined the efficacy of titrating blood pressure in younger patients with shock secondary to either penetrating or blunt injury; in both trials, overall mortality was not improved. Another two major clinical trials suggest that controlled resuscitation may be safe in patients with blunt injury in the pre-hospital setting and possibly lead to improved outcomes, especially in patients with pre-hospital hypotension. Some animal studies suggest that hypotensive resuscitation may improve outcomes in subjects with penetrating injury where bleeding occurs from only one site. On the other hand, hypotensive resuscitation in blunt trauma may worsen outcomes due to tissue hypoperfusion. The influence of these approaches on coagulation has not been sufficiently examined, even in animal studies. The effectiveness of permissive hypotension/hypotensive resuscitation and restricted/controlled resuscitation is still inconclusive, even when examining systematic reviews and meta-analyses. Further investigation is needed to elucidate the effectiveness of these approaches, so as to develop improved treatment strategies which take into account coagulopathy in the pathophysiology of trauma.

Fluid resuscitation in pre-hospital trauma care: a consensus view

Fluid administration for trauma in the pre-hospital environment is a challenging and controversial area. The available evidence does not clearly support any single approach. Nevertheless, some provisional conclusions may be drawn. We believe that the following guidelines represent a sound expert consensus. It is intended that they will be modifi ed as future research brings clarity to the area. When treating trauma victims in the pre-hospital arena cannulation should take place en route where possible. Only two attempts at cannulation should be made. Transfer should not be delayed by attempts to obtain intravenous access. Entrapped patients require cannulation at the scene. Normal saline may be titrated in boluses of 250 ml against the presence or absence of a radial pulse (caveats; penetrating torso injury, head injury, infants).

Echocardiography in shock management

Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.

In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.

The four core types of shock—cardiogenic, hypovolemic, obstructive, and vasoplegic—can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.

The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock.

The effect of scene time on survival

A review of the literature was carried out to determine the importance of pre-hospital scene times and how it can be affected. In the UK, and certain centres in North America, mortality and morbidity in critically injured patients appears to be related to scene times. The majority of these patients only require basic life support at the scene. Consequently the possible benefits of more advanced procedure need to be compared with the transportation period, the time needed to mobilize a medical team and skill proficiency. Cardiovascular resuscitation procedures in particular require reappraisal. Though haemostasis is essential, there is little evidence to support the use of fluid resuscitation in nontrapped urban patients with a significant haemorrhage problem. In contrast patients who are not bleeding do appear to benefit from advanced life support procedures even though this increases scene time. There is therefore a need for pre-hospital paramedic workers to triage patients so that appropriate resuscitation can be carried out.

Pre-hospital fluids - when and how much?

When to give intravenous fluids, how much to give and whether intravenous fluids improve patient outcome remain controversial areas. Hypovolaemic shut down patients are difficult to connulate. The on scene is protracted and invariably relatively small volumes of fluid are infused. Those patients who are hypotensive invariably require definitive surgical intervention, therefore, any delay in reaching hospital can worsen outcome. Intravenous fluids given in states of uncontrolled and noncompressible bleeding will enhance blood loss. There is therefore a need to define those patient groups requiring pre-hospital intervention and optimal recusitation objectives in terms of blood pressure in the pre-hospital scene. This paper examines the current evidence base in both animal and human trials and makes recommendations for optimal fluid management in the trauma patient.

Does the infusion rate of fluid affect rapidity of mean arterial pressure restoration during controlled hemorrhage

OBJECTIVE

This study aimed to compare 2 fluid infusion rates of lactated Ringer (LR) and hydroxyethyl starch (HES) 130/0.4 on hemodynamic restoration at the early phase of controlled hemorrhagic shock.

METHODS

Fifty-six anesthetized and ventilated piglets were bled until mean arterial pressure (MAP) reached 40 mm Hg. Controlled hemorrhage was maintained for 30 minutes. After this period, 4 resuscitation groups were studied (n=14 for each group): HES infused at 1 or 4mL/kg per minute or LR1 infused at 1 or 4mL/kg per minute until baseline MAP was restored. Hemodynamic assessment using PiCCO monitoring and biological data were collected.

RESULTS

Time to restore baseline MAP ±10% was significantly lower in LR4 group (11±11 minutes) compared to LR1 group (41±25 minutes) (P=.0004). Time to restore baseline MAP ±10% was significantly lower in HES4 group (4±3 minutes) compared to HES1 (11±4 minutes) (P=.0003). Time to restore baseline MAP ±10% was significantly lower with HES vs LR whatever the infusion rate. No statistically significant difference was observed in cardiac output, central venous saturation, extravascular lung water, and arterial lactate between 4 and 1 mL/kg per minute groups.

CONCLUSIONS

In this controlled hemorrhagic shock model, a faster infusion rate (4 vs 1mL/kg per minute) significantly decreased the time for restoring baseline MAP, regardless of the type of infused fluid. The time for MAP restoration was significantly shorter for HES as compared to LR whatever the fluid infusion rate.

Evaluation of Prehospital Blood Products to Attenuate Acute Coagulopathy of Trauma in a Model of Severe Injury and Shock in Anesthetized Pigs

Acute trauma coagulopathy (ATC) is seen in 30% to 40% of severely injured casualties. Early use of blood products attenuates ATC, but the timing for optimal effect is unknown. Emergent clinical practice has started prehospital deployment of blood products (combined packed red blood cells and fresh frozen plasma [PRBCs:FFP], and alternatively PRBCs alone), but this is associated with significant logistical burden and some clinical risk. It is therefore imperative to establish whether prehospital use of blood products is likely to confer benefit. This study compared the potential impact of prehospital resuscitation with (PRBCs:FFP 1:1 ratio) versus PRBCs alone versus 0.9% saline (standard of care) in a model of severe injury. Twenty-four terminally anesthetised Large White pigs received controlled soft tissue injury and controlled hemorrhage (35% blood volume) followed by a 30-min shock phase. The animals were allocated randomly to one of three treatment groups during a 60-min prehospital evacuation phase: hypotensive resuscitation (target systolic arterial pressure 80 mmHg) using either 0.9% saline (group 1, n = 9), PRBCs:FFP (group 2, n = 9), or PRBCs alone (group 3, n = 6). Following this phase, an in-hospital phase involving resuscitation to a normotensive target (110 mmHg systolic arterial blood pressure) using PRBCs:FFP was performed in all groups. There was no mortality in any group. A coagulopathy developed in group 1 (significant increase in clot initiation and dynamics shown by TEG [thromboelastography] R and K times) that persisted for 60 to 90 min into the in-hospital phase. The coagulopathy was significantly attenuated in groups 2 and 3 (P = 0.025 R time and P = 0.035 K time), which were not significantly different from each other. Finally, the volumes of resuscitation fluid required was significantly greater in group 1 compared with groups 2 and 3 (P = 0.0067) (2.8 ± 0.3 vs. 1.9 ± 0.2 and 1.8 ± 0.3 L, respectively). This difference was principally due to a greater volume of saline used in group 1 (P = 0.001). Prehospital PRBCs:FFP or PRBCs alone may therefore attenuate ATC. Furthermore, the amount of crystalloid may be reduced with potential benefit of reducing the extravasation effect and later tissue edema.

Indication Bias Explains Some of the Observed Increased Mortality Associated With Use of Prehospital Intravenous Fluids in a Pediatric Trauma Population

OBJECTIVES

Traditionally, in both pediatric and adult trauma patients, management of hemorrhage and shock has included early rapid intravenous fluid (IVF) replacement at the scene or during transport to a definitive care facility. Because prehospital resuscitation can be considered as a lifesaving intervention, severely injured patients are more likely to receive IVF. Observational studies not adequately adjusting for this confounding by indication (indication bias) while evaluating the impact of prehospital IVF on mortality in clinically heterogeneous patient populations are likely to find an increased mortality associated with the use of prehospital IVF, an association that may be spurious even after traditional multivariable risk adjustment. Propensity scores can be used to mitigate the impact of this selection bias on the estimated effect. The authors hypothesized that the effect of IVF on mortality will differ based on whether propensity scores (based on a set of prehospital indications for IVF) are adjusted for in a multivariable outcome model.

METHODS

This was a retrospective cohort study of severely injured pediatric (<18 years) patients consecutively evaluated and treated between January 1, 2008, and June 30, 2011, at Oklahoma's only Level I pediatric trauma center. Patients were divided into those receiving 250 mL or more (GE250 group) and those receiving less (LT250 group) of prehospital IVF based on area under curve (AUC) analysis (AUC = 0.7, 95% confidence interval [CI] = 0.6 to 0.80, sensitivity = 0.81 and specificity = 0.56). Propensity scores were used to minimize confounding by indication of the mortality estimate and were calculated based on measurable prehospital factors. Using Cox's regression to minimize survival bias, the independent effect of prehospital IVF on the risk of 30-day in-hospital mortality was evaluated with and without adjusting for the propensity to receive 250 mL of prehospital IVF.

RESULTS

A total of 482 patients met study criteria. Of these, 46.3% (223 of 449) were in the GE250 group. After adjusting for Injury Severity Score, presence of a severe head injury, shock, and a penetrating injury, all of which were significant predictors of mortality, receiving 250 mL or more of prehospital IVF was significantly associated with an almost threefold increase in the risk of 30-day in-hospital mortality (hazard ratio [HR] = 2.96, 95% CI = 1.1 to 8.2). However, further adjusting for the propensity to be in the GE250 group, in addition to the aforementioned variables, attenuated the effect estimate and resulted in a nonsignificant (p = 0.3408), more precise association between prehospital IVF and mortality (HR = 1.9, 95% CI = 0.6 to 6.6).

CONCLUSIONS

Propensity-adjusted survival analysis suggests that the observed increased risk in mortality associated with use of prehospital IVF replacement may be a spurious association resulting from inadequate control of confounding by indication inherent in observational studies. In the absence of patient subgroup-specific results from well-controlled studies, IVF resuscitation should not be a reason to delay patient transport to a definitive care facility. Randomized trials evaluating the effect of prehospital fluids are warranted in the pediatric trauma population, as such studies have shown clinical significance in the adult trauma population.

Rediscovering the wound hematoma as a site of hemostasis during major arterial hemorrhage

BACKGROUND

Treatments for major internal bleeding after injury include permissive hypotension to decrease the rate of blood loss, intravenous infusion of plasma or clotting factors to improve clot formation, and rapid surgical hemostasis or arterial embolization to control bleeding vessels. Yet, little is known regarding major internal arterial hemostasis, or how these commonly used treatments might influence hemostasis.

OBJECTIVES

(i) To use a swine model of femoral artery bleeding to understand the perivascular hemostatic response to contained arterial hemorrhage. (ii) To directly confirm the association between hemodynamics and bleeding velocity. (iii) To observe the feasibility of delivering an activated clotting factor directly to internal sites of bleeding using a simplified angiographic approach.

METHODS

Ultrasound was used to measure bleeding velocity and in vivo clot formation by elastography in a swine model of contained femoral artery bleeding with fluid resuscitation. A swine model of internal pelvic and axillary artery hemorrhage was also used to demonstrate the feasibility of local delivery of an activated clotting factor.

RESULTS

In this model, clots formed slowly within the peri-wound hematoma, but eventually contained the bleeding. Central hemodynamics correlated positively with bleeding velocity. Infusion of recombinant human activated factor VII into the injured artery near the site of major internal hemorrhage in the pelvis and axillae was feasible.

CONCLUSIONS

We rediscovered that clot formation within the peri-wound hematoma is an integral component of hemostasis and a feasible target for the treatment of major internal bleeding using activated clotting factors delivered using a simplified angiographic approach.

Resuscitation Using Liposomal Vasopressin in an Animal Model of Uncontrolled Hemorrhagic Shock

Background

Current research suggests that administration of vasopressin to patients with uncontrolled hemorrhagic shock (UHS) can avoid the detrimental effects associated with aggressive fluid resuscitation. However, vasopressin has a short half-life of 10~35 minutes in in vivo use and precludes its use in the pre-hospital setting. To increase the half-life of vasopressin, we proposed to synthesize liposome-encapsulated vasopressin and test it in a rat model of UHS.

Methods

The film hydration method was used to prepare liposomal vasopressin consisting of: Dipalmitoylphosphatidylcholine, cholesterol, and dipalmitoyl phosphatidylethanolamine (20:20:1 mole ratio). 42 rats were subjected to UHS and randomly received 5 different treatments (vasopressin, liposomal vasopressin, lactate ringer (LR), liposome only and sham). Outcome of UHS were measured using 4 common prognostic tests: mean arterial pressure (MAP), serum lactate level, inflammatory profile and pulmonary edema.

Results

The dynamic light scattering results confirmed that we had prepared a successful liposomal vasopressin complex. Comparing the serum vasopressin concentration of liposomal vasopressin and vasopressin treated animals by ELISA, we found that the concentration of vasopressin for the liposomal vasopressin treated group is higher at 60 minutes. However, there was no significant difference between the MAP profile of rats treated with vasopressin and liposomal vasopressin in UHS. We also observed that animals treated with liposomal vasopressin performed indifferently to vasopressin treated rats in serum lactate level, inflammatory profile and edema profile. For most of our assays, the liposome only control behaves similarly to LR resuscitation in UHS rats.

Conclusion

We have synthesized a liposomal vasopressin complex that can prolong the serum concentration of vasopressin in a rat model of UHS. Although UHS rats treated with either liposomal vasopressin or vasopressin showed no statistical differences, it would be worthwhile to repeat the experiments with different liposomal compositions.

Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine

OBJECTIVE

Circulatory shock is a life-threatening syndrome resulting in multiorgan failure and a high mortality rate. The aim of this consensus is to provide support to the bedside clinician regarding the diagnosis, management and monitoring of shock.

METHODS

The European Society of Intensive Care Medicine invited 12 experts to form a Task Force to update a previous consensus (Antonelli et al.: Intensive Care Med 33:575-590, 2007). The same five questions addressed in the earlier consensus were used as the outline for the literature search and review, with the aim of the Task Force to produce statements based on the available literature and evidence. These questions were: (1) What are the epidemiologic and pathophysiologic features of shock in the intensive care unit? (2) Should we monitor preload and fluid responsiveness in shock? (3) How and when should we monitor stroke volume or cardiac output in shock? (4) What markers of the regional and microcirculation can be monitored, and how can cellular function be assessed in shock? (5) What is the evidence for using hemodynamic monitoring to direct therapy in shock? Four types of statements were used: definition, recommendation, best practice and statement of fact.

RESULTS

Forty-four statements were made. The main new statements include: (1) statements on individualizing blood pressure targets; (2) statements on the assessment and prediction of fluid responsiveness; (3) statements on the use of echocardiography and hemodynamic monitoring.

CONCLUSIONS

This consensus provides 44 statements that can be used at the bedside to diagnose, treat and monitor patients with shock.

Haemodynamic changes in trauma

Trauma is the leading cause of death during the first four decades of life in the developed countries. Its haemodynamic response underpins the patient's initial ability to survive, and the response to treatment and subsequent morbidity and resolution. Trauma causes a number of insults including haemorrhage, tissue injury (nociception) and, predominantly, in military casualties, blast from explosions. This article discusses aspects of the haemodynamic responses to these insults and subsequent treatment. 'Simple' haemorrhage (blood loss without significant volume of tissue damage) causes a biphasic response: mean arterial blood pressure (MBP) is initially maintained by the baroreflex (tachycardia and increased vascular resistance, Phase 1), followed by a sudden decrease in MAP initiated by a second reflex (decrease in vascular resistance and bradycardia, Phase 2). Phase 2 may be protective. The response to tissue injury attenuates Phase 2 and may cause a deleterious haemodynamic redistribution that compromises blood flow to some vital organs. In contrast, thoracic blast exposure augments Phase 2 of the response to haemorrhage. However, hypoxaemia from lung injury limits the effectiveness of hypotensive resuscitation by augmenting the attendant shock state. An alternative strategy ('hybrid resuscitation') whereby tissue perfusion is increased after the first hour of hypotensive resuscitation by adopting a revised normotensive target may ameliorate these problems. Finally, morphine also attenuates Phase 2 of the response to haemorrhage in some, but not all, species and this is associated with poor outcome. The impact on human patients is currently unknown and is the subject of a current physiological investigation.

Damage control resuscitation: permissive hypotension and massive transfusion protocols

Evidence for changes in adult trauma management often precedes evidence for changes in pediatric trauma management. Many adult trauma centers have adopted damage-control resuscitation management strategies, which target the metabolic syndrome of acidosis, coagulopathy, and hypothermia often found in severe uncontrolled hemorrhage. Two key components of damage-control resuscitation are permissive hypotension, which is a fluid management strategy that targets a subnormal blood pressure, and hemostatic resuscitation, which is a transfusion strategy that targets coagulopathy with early blood product administration. Acceptance of damage-control resuscitation strategies is reflected in recent changes in the American College of Surgeons' Advanced Trauma Life Support curriculum; the most recent edition has decreased its initial fluid recommendation to 1 L from 2 L, and it now recommends early administration of blood products without specifying any specific ratio. These recommendations are not advocating permissive hypotension or hemostatic resuscitation directly but represent an initial step toward limiting fluid resuscitation and using blood products to treat coagulopathy earlier. Evidence for permissive hypotension exists in animal studies and few adult clinical trials. There is no evidence to support permissive hypotension strategies in pediatrics. Evidence for hemostatic resuscitation in adult trauma management is more comprehensive, and there are limited data to support its use in pediatric trauma patients with severe hemorrhage. Additional studies on the management of children with severe uncontrolled hemorrhage are needed.

Predictors of hypofibrinogenemia in blunt trauma patients on admission

PURPOSE

Massive bleeding usually leads to critically low levels of clotting factors, including fibrinogen. Although reduced fibrinogen levels correlate with increased mortality, predictors of hypofibrinogenemia have remained poorly understood. We investigated whether findings available on admission can be used as predictors of hypofibrinogenemia.

METHODS

We retrospectively reviewed serum fibrinogen levels tested on arrival in 290 blunt trauma patients transported to a level I trauma center during a 3-year period. The primary outcome was prehospital predictors for hypofibrinogenemia. Covariates included age, sex, prehospital fluid therapy, prehospital anatomical and physiological scores, time from injury, base excess, and lactate on arrival. All variables with values of p < 0.10 in univariate analysis were included in a multivariate logistic regression model. The relationships between the variables and the 7-day mortality rate were evaluated in a Cox proportional hazards model.

RESULTS

Patient's age [odds ratio (OR): 0.97, p < 0.001], Triage Revised Trauma Score (T-RTS) (OR: 0.81, p = 0.003), and prehospital fluid therapy (OR: 2.54, p = 0.01) were detected as independent predictors for hypofibrinogenemia in multivariate logistic regression analysis. Serum fibrinogen level [hazard ratio (HR): 0.99, p = 0.01] and T-RTS (HR: 0.77, p < 0.01) were associated with the 7-day mortality rate.

CONCLUSION

T-RTS is considered to play an important role in predicting hypofibrinogenemia and 7-day mortality in blunt trauma patients.

Effects of different fluid regimes and desmopressin on uncontrolled hemorrhage during hypothermia in the rat

Resuscitation with large volumes of crystalloids during traumatic hemorrhagic shock might increase the mortality by inducing rebleeding. However, few studies have addressed this problem during hypothermic conditions. Sixty-eight Sprague-Dawley rats were exposed to a standardized femoral artery injury and resuscitated with low (LRe), medium (MRe), or high (HRe) intensity using lactated Ringer's solution after being cooled to 30°C. An additional MRe group was also given desmopressin since this drug might reverse hypothermic-induced impairment of the primary hemostasis. The rats were rewarmed after 90 minutes and observed for 3 hours. The incidence, on-set time, duration, and volume of bleedings and hemodynamic changes were recorded. Rebleedings occurred in 60% of all animals and were more voluminous in the HRe group than in the LRe group (p=0.01). The total rebleeding volume per animal increased with the rate of fluid administration (r=0.50, p=0.01) and the duration of each rebleeding episode was longer in the HRe group than in the LRe group (p<0.001). However, the mortality tended to be higher in the LRe group (LRe=6/15, MRe=1/15, HRe=2/15, p=0.07). Desmopressin did not change the bled volume or the mortality. Overall, the mortality increased if rebleeding occurred (10/35 rebleeders died vs. 1/25 nonrebleeders, p=0.015). Liberal fluid administration increased the rebleeding volume while a trend toward higher mortality was seen with the restrictive fluid program. Desmopressin had no effect on the studied parameters.

Timing and volume of fluid administration for patients with bleeding

BACKGROUND

Treatment of haemorrhagic shock involves maintaining blood pressure and tissue perfusion until bleeding is controlled. Different resuscitation strategies have been used to maintain the blood pressure in trauma patients until bleeding is controlled. However, while maintaining blood pressure may prevent shock, it may worsen bleeding.

OBJECTIVES

To examine the effect on mortality and coagulation times of two intravenous fluid administration strategies in the management of haemorrhagic hypovolaemia, early compared to delayed administration and larger compared to smaller volume of fluid administered.

SEARCH METHODS

We searched the Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R), Embase Classic + Embase (OvidSP), ISI Web of Science (SCI-Expanded and CPCI-S) and clinical trials registries. We checked reference lists of identified articles and contacted authors and experts in the field. The most recent search was run on 5 February 2014.

SELECTION CRITERIA

Randomised trials of the timing and volume of intravenous fluid administration in trauma patients with bleeding. Trials in which different types of intravenous fluid were compared were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality.

MAIN RESULTS

Six trials involving a total of 2128 people were included in this review. We did not combine the results quantitatively because the interventions and patient populations were so diverse. Early versus delayed fluid administration Three trials reported mortality and two reported coagulation data.In the first trial (n = 598) the relative risk (RR) for death with early fluid administration was 1.26 (95% confidence interval (CI) 1.00 to 1.58). The weighted mean differences (WMD) for prothrombin time and partial thromboplastin time were 2.7 (95% CI 0.9 to 4.5) and 4.3 (95% CI 1.74 to 6.9) seconds, respectively.In the second trial (n = 50) the RR for death with early blood transfusion was 5.4 (95% CI 0.3 to 107.1). The WMD for partial thromboplastin time was 7.0 (95% CI 6.0 to 8.0) seconds. In the third trial (n = 1309) the RR for death with early fluid administration was 1.06 (95% CI 0.77 to 1.47). Larger versus smaller volume of fluid administration Three trials reported mortality and one reported coagulation data.In the first trial (n = 36) the RR for death with a larger volume of fluid resuscitation was 0.80 (95% CI 0.28 to 22.29). Prothrombin time and partial thromboplastin time were 14.8 and 47.3 seconds in those who received a larger volume of fluid, as compared to 13.9 and 35.1 seconds in the comparison group.In the second trial (n = 110) the RR for death with a high systolic blood pressure resuscitation target (100 mm Hg) maintained with a larger volume of fluid as compared to a low systolic blood pressure resuscitation target (70 mm Hg) maintained with a smaller volume of fluid was 1.00 (95% CI 0.26 to 3.81). In the third trial (n = 25) there were no deaths.

AUTHORS' CONCLUSIONS

We found no evidence from randomised controlled trials for or against early or larger volume of intravenous fluid administration in uncontrolled haemorrhage. There is continuing uncertainty about the best fluid administration strategy in bleeding trauma patients. Further randomised controlled trials are needed to establish the most effective fluid resuscitation strategy.

Combat Casualty Care research programme

The Combat Casualty Care research programme is an integrated suite of projects designed to address Defence Medical Services' research needs for casualty care. The programme covers a broad spectrum of topics ranging from the pathophysiological and immunological impact of military relevant injuries to the effects of these disturbances on the response to early treatment. Dstl Porton Down has a long history of studying military injuries and has developed models, both in vivo and physical, to address the research needs. The work is conducted in close collaboration with clinical colleagues at the Royal Centre for Defence Medicine who have direct experience of the clinical issues faced by combat casualties and insights into the potential clinical implications of emerging strategies. This article reviews progress in research areas spanning forward resuscitation, with a particular focus on blast-related injuries, trauma coagulopathy, effects of drugs on the response to haemorrhage and deployed research. A significant 'value added' component has been the underpinning of higher degrees for seconded military clinicians at Dstl Porton Down who have made a valuable contribution to the overall programme.

Target blood pressure for hypotensive resuscitation

BACKGROUND

Good outcomes have resulted from hypotensive resuscitation of hemorrhagic shock patients. We hypothesized that mean arterial pressure (MAP) 60mmHg is the target blood pressure for hypotensive resuscitation during uncontrolled hemorrhagic shock in trauma.

METHODS

To determine the effective target MAP for hypotensive resuscitation during uncontrolled hemorrhagic shock, we randomly assigned 80 rats to one of 8 treatment groups (n=10 for each group). We then observed the effects of different target MAPs (control, 40, 50, 60, 70, 80, 90mmHg, and sham) on fluid resuscitation of uncontrolled hemorrhagic shock. Blood pressure, serum lactate, hematocrit, fluid therapy, blood loss, and plasma cytokine levels were measured at 0, 30, 90, 120, 180, 240, 300min after the start of the surgical procedure.

RESULTS

A target MAP of 90, 80 and 70mmHg had increased blood loss and decreased hematocrit and IL-6 and TNF-α production. A target MAP of 60, 50 and 40mmHg had lower blood loss, good hematocrit, higher IL-6 and TNF-α production, and decreased animal survival. Only target MAPs of 40 and 50 had and decreased animal survival. The differences in blood loss, hematocrit, lactate, post-resuscitation MAP, survival, IL-6, IL-10, and TNF-α production between rats with a target MAP of 60mmHg and those with a target MAP of 70mmHg were not significant. The amount of fluid therapy in the BP 60 groups was less than in the BP 70 groups (P<0.001).

CONCLUSION

A MAP of 60mmHg should be considered for evaluation in human studies as a target for hypotensive resuscitation.

Ideal resuscitation pressure for uncontrolled hemorrhagic shock in different ages and sexes of rats

INTRODUCTION

Our previous studies demonstrated that 50-60 mmHg mean arterial blood pressure was the ideal target hypotension for uncontrolled hemorrhagic shock during the active hemorrhage in sexually mature rats. The ideal target resuscitation pressure for immature and older rats has not been determined.

METHODS

To elucidate this issue, using uncontrolled hemorrhagic-shock rats of different ages and sexes (6 weeks, 14 weeks and 1.5 years representing pre-adult, adult and older rats, respectively), the resuscitation effects of different target pressures (40, 50, 60, 70 and 80 mmHg) on uncontrolled hemorrhagic shock during active hemorrhage and the age and sex differences were observed.

RESULTS

Different target resuscitation pressures had different resuscitation outcomes for the same age and sex of rats. The optimal target resuscitation pressures for 6-week-old, 14-week-old and 1.5-year-old rats were 40 to 50 mmHg, 50 to 60 mmHg and 70 mmHg respectively. Ideal target resuscitation pressures were significantly superior to other resuscitation pressures in improving the hemodynamics, blood perfusion, organ function and animal survival of uncontrolled hemorrhagic-shock rats (P < 0.01). For same target resuscitation pressures, the beneficial effect on hemorrhagic shock had a significant age difference (P < 0.01) but no sex difference (P > 0.05). Different resuscitation pressures had no effect on coagulation function.

CONCLUSION

Hemorrhagic-shock rats at different ages have different target resuscitation pressures during active hemorrhage. The ideal target resuscitation hypotension for 6-week-old, 14-week-old and 1.5-year-old rats was 40 to 50 mmHg, 50 to 60 mmHg and 70 mmHg, respectively. Their resuscitation effects have significant age difference but had no sex difference.

Efficacy of centhaquin as a small volume resuscitative agent in severely hemorrhaged rats

Centhaquin has been reported to be an effective resuscitative agent. The present study was carried out to determine resuscitative effect of centhaquin when administered using a small volume of 3% hypertonic saline (HS) to hemorrhaged rats. Sprague-Dawley rats were anesthetized with urethane, and a pressure catheter SPR-320 was placed in the left femoral artery; another pressure-volume catheter SPR-869 was placed into the left ventricle. Hemorrhage was induced by withdrawing blood and mean arterial pressure (MAP) was maintained at 35 mm Hg for 30 minutes after which resuscitation was performed. Animals were divided in 2 groups: group A received HS and group B received centhaquin (0.05 mg/kg) dissolved in HS. The time by which MAP fell back to 35 mm Hg was observed at that time all animals were administered fresh blood. It was found that centhaquin significantly reduced blood lactate and improved cardiac output and MAP of hemorrhaged rats compared with HS. The time by which MAP fell back to 35 mm Hg in rats treated with HS was 55 ± 6 minutes, whereas it was 161 ± 14 minutes in centhaquin treated rats. Survival time following administration of fresh blood was 79 ± 7 minutes in vehicle-treated group, whereas it was 105 ± 9 minutes in centhaquin-treated rats. The total time of survival of rats treated with HS or centhaquin was 134 ± 12 minutes and 266 ± 16 minutes, respectively. Centhaquin, in small volume, maintained MAP of hemorrhaged rats for a considerable long time and improved the survival time.

Hemodilution as a result of aggressive fluid resuscitation aggravates coagulopathy in a rat model of uncontrolled hemorrhagic shock

BACKGROUND

The relationship between dilution caused by fluid resuscitation and blood coagulability during ongoing, uncontrolled hemorrhagic shock (UHS) remains unclear. We hypothesized that dilution caused by fluid resuscitation may impair blood coagulability in UHS.

METHODS

Eighteen rats underwent under halothane anesthesia. The UHS model consisted of the following phases: (1) an initial blood withdrawal of 2.5 mL per 100 g during 15 minutes, followed by UHS via tail amputation and fluid resuscitation with lactated Ringer's (LR) solution (0-60 minutes); (2) hemostasis and reinfusion of withdrawn blood and additional LR solution (60-100 minutes); and (3) observation of awake rats for 72 hours. Rats were randomized into three resuscitation regimens (n = 6 per group) during Phase I. LR solution was infused at a rate of 0.1 mL/min in Group 1, 0.25 mL/min in Group 2, and 0.75 mL/min in Group 3. Blood coagulability was assessed with a Sonoclot analysis, and survival to 72 hours were compared between groups.

RESULTS

Both resuscitation regimens of Groups 2 and 3 increased the blood pressure and bleeding volume from the tail stump compared with Group 1 (p < 0.05). At the end of Phase I, the hematocrit decreased to 29% (3%) in Group 1, 23% (3%) in Group 2, and 12% (3%) in Group 3 (p < 0.05). Sonoclot analysis revealed a decreased clot rate of 16 (9) clot signal per minute in Group 2 and 14 (10) clot signal per minute in Group 3 compared with Group 1 (40 [10] clot signal per minute; p < 0.01). There was a significant correlation between clot rate and hematocrit values (r = +0.67, p < 0.01). Compared with Group 1, survival improved in Groups 2 and 3 (p < 0.05).

CONCLUSION

In a rat model of UHS, aggressive fluid resuscitation aggravated hemodilution and blood coagulability as well as and bleeding but improved the hemodynamics and survival. There was a positive correlation between hemodilution and coagulation indexes. Hemodilution, as part of fluid therapy, may affect coagulopathy in UHS.

Trauma care today, what's new?

Injury is the fourth leading cause of death in the US, and the leading cause of death in younger age. Trauma is primarily a disease of the young and accounts for more years of productive life lost than any other illness. Consequently, almost every health care provider encounters trauma patients from time to time. Many of these patients are critically ill and pose several challenges in the acute phase, including airway and ventilation, fluid management, intracranial pressure control, etc. In the last decade, several strategies and treatment options have been studied in trauma care along with improvement in technologies. In this review, we will discuss a few of the new developments and updates in trauma care.

The haemodynamic response to pre-hospital RSI in injured patients

BACKGROUND

Laryngoscopy and tracheal intubation provoke a marked sympathetic response, potentially harmful in patients with cerebral or cardiovascular pathology or haemorrhage. Standard pre-hospital rapid sequence induction of anaesthesia (RSI) does not incorporate agents that attenuate this response. It is not known if a clinically significant response occurs following pre-hospital RSI or what proportion of injured patients requiring the intervention are potentially at risk in this setting.

METHODS

We performed a retrospective analysis of 115 consecutive pre-hospital RSI's performed on trauma patients in a physician-led Helicopter Emergency Medical Service. Primary outcome was the acute haemodynamic response to the procedure. A clinically significant response was defined as a greater than 20% change from baseline recordings during laryngoscopy and intubation.

RESULTS

Laryngoscopy and intubation provoked a hypertensive response in 79% of cases. Almost one-in-ten patients experienced a greater than 100% increase in mean arterial pressure (MAP) and/or systolic blood pressure (SBP). The mean (95% CI) increase in SBP was 41(31-51) mmHg and MAP was 30(23-37) mmHg. Conditions leaving the patient vulnerable to secondary injury from a hypertensive response were common.

CONCLUSIONS

Laryngoscopy and tracheal intubation, following a standard pre-hospital RSI, commonly induced a clinically significant hypertensive response in the trauma patients studied. We believe that, although this technique is effective in securing the pre-hospital trauma airway, it is poor at attenuating adverse physiological effects that may be detrimental in this patient group.

Association of hemodilution and blood pressure in uncontrolled bleeding

BACKGROUND

Hemodynamic status and coagulation capacity affect blood loss after injury. The most advantageous fluid and blood pressure to optimize resuscitation and minimize perturbation of coagulation are unclear. We investigated interactions of isovolumic hemodilution on hemodynamics, coagulation, and blood loss after injury.

METHODS

Twenty-five male rats were randomized into three groups (Whole Blood Uncontrolled Blood Pressure [WBU], n = 7; Lactated Ringers Uncontrolled Blood Pressure [LRU], n = 10; Whole Blood Controlled Blood Pressure [WBC], n = 8) with isovolumic hemodilution of 50% blood volume, with and without control of pre-injury blood pressure. All rats underwent uniform grade IV liver injury 30 min after serial exchanges. Post-injury blood loss and coagulation function were measured.

RESULTS

Dilution occurred, determined by hematocrit, with LRU having a greater reduction. Pre-injury mean arterial pressure (MAP) decreased compared with baseline (98 ± 7 mmHg) with LRU (62 ± 14 mmHg) and WBC (61 ± 10 mmHg), resulting in WBU (101 ± 13 mmHg) being significantly higher and not changed from baseline. Post-injury, MAP decreased from pre-injury, with LRU significantly lower than the other two groups. No differences were observed in prothrombin time/international normalized ratio or thromboelastography. Bleed volume was significantly different between groups: WBU < WBC < LRU and associated with the pre-injury MAP. Controlling baseline MAP, dilution with Lactated Ringers (LR) resulted in greater blood loss than whole blood (3.0 ± 0.4 versus 1.9 ± 0.3 mL).

CONCLUSIONS

In this rat model of liver injury, blood loss was associated with baseline MAP and type of fluid used for dilution. Hemodilution with LR did not produce coagulopathy based on laboratory values. When controlling baseline MAP, dilution with LR increased bleeding, confirming a functional coagulopathic state.

Adenocaine and Mg(2+) reduce fluid requirement to maintain hypotensive resuscitation and improve cardiac and renal function in a porcine model of severe hemorrhagic shock*

OBJECTIVES

Hypotensive resuscitation is gaining clinical acceptance in the treatment of hemorrhagic shock. Our aims were to investigate: 1) the effect of 7.5% NaCl with adenocaine (adenosine and lidocaine, AL) and AL with Mg (ALM) on fluid requirement to maintain a minimum mean arterial pressure of 50 mm Hg, and 2) the effect of a second bolus of 0.9% NaCl with AL during return of shed blood on cardiac and renal function in a porcine model of hemorrhagic shock.

DESIGN

Pigs were randomized to: Sham (n = 5), Sham + ALM/AL (n = 5), hemorrhage control (n = 11), or hemorrhage + ALM/AL (n = 9). Hemorrhage animals were bled to a mean arterial pressure of 35 mm Hg. After 90 mins, pigs were fluid resuscitated with Ringers acetate and 20 mL 7.5% NaCl with ALM to maintain a target mean arterial pressure of minimum 50 mm Hg. Shed blood and 0.9% NaCl with AL were infused 30 mins later. Hemorrhage control group was subjected to the same protocol but without ALM/AL. Hemodynamics, cardiodynamics (pressure-volume analysis), oxygen consumption, and kidney function were measured for 6 hrs.

SETTING

University hospital laboratory.

SUBJECTS

Female farm-bred pigs.

RESULTS

Fluid volume infused during hypotensive resuscitation was 40% less in the 7.5% NaCl-/ALM-treated pigs than controls (25 vs. 41 mL/kg, p < .05). ALM was associated with a significant increase in dp/dtmax, end-systolic blood pressure, and systemic vascular resistance. Return of shed blood and 0.9% NaCl/AL reduced whole body oxygen consumption by 27% (p < .05), and significantly improved the end-systolic pressure-volume relationship and preload recruitable stroke work compared to controls. Glomerular filtration rate in the ALM/AL group returned to 83% of baseline compared to 54% in controls (p = .01).

CONCLUSION

Resuscitation with 7.5% NaCl ALM increases cardiac function and reduces fluid requirements during hypotensive resuscitation, whereas a second AL infusion during blood resuscitation transiently reduces whole body oxygen consumption and improves cardiac and renal function.

Fluid therapy in uncontrolled hemorrhage--what experimental models have taught us

Intravenous fluid is life-saving in hypovolemic shock, but fluid sometimes aggravates the bleeding. During the past 25 years, animal models have helped our understanding of the mechanisms involved in this unexpected effect. A key issue is that vasoconstriction is insufficient to arrest the bleeding when damage is made to a major blood vessel. 'Uncontrolled hemorrhage' is rather stopped by a blood clot formed at the outside surface of the vessel, and the immature clot is sensitive to mechanical and chemical interactions. The mortality increases if rebleeding occurs. In the aortic tear model in swine, hemorrhage volume and the mortality increase from effective restoration of the arterial pressure. The mortality vs. amount of fluid curve is U-shaped with higher mortality at either end. Without any fluid at all, irreversible shock causes death provided the hemorrhage is sufficiently large. Crystalloid fluid administered in a 3 : 1 proportion to the amount of lost blood initiates serious rebleeding. Hypertonic saline 7.5% in 6% dextran 70 (HSD) also provokes rebleeding resulting in higher mortality in the recommended dosage of 4 ml/kg. Uncontrolled hemorrhage models in rats, except for the 'cut-tail' model, confirm the results from swine. To avoid rebleeding, fluid programs should not aim to fully restore the arterial pressure, blood flow rates, or blood volume. For a hemorrhage of 1000 ml, computer simulations show that deliberate hypovolemia (-300 ml) would be achieved by infusing 600-750 ml crystalloid fluid over 20-30 min or 100 ml of HSD over 10-20 min in an adult male.