Hypotensive Resuscitation

Blood failure: traumatic hemorrhage and the interconnections between oxygen debt, endotheliopathy, and coagulopathy

This review explores the concept of "blood failure" in traumatic injury, which arises from the interplay of oxygen debt, the endotheliopathy of trauma (EoT), and acute traumatic coagulopathy (ATC). Traumatic hemorrhage leads to the accumulation of oxygen debt, which can further exacerbate hemorrhage by triggering a cascade of events when severe. Such events include EoT, characterized by endothelial glycocalyx damage, and ATC, involving platelet dysfunction, fibrinogen depletion, and dysregulated fibrinolysis. To manage blood failure effectively, a multifaceted approach is crucial. Damage control resuscitation strategies such as use of permissive hypotension, early hemorrhage control, and aggressive transfusion of blood products including whole blood aim to minimize oxygen debt and promote its repayment while addressing endothelial damage and coagulation. Transfusions of red blood cells, plasma, and platelets, as well as the use of tranexamic acid, play key roles in hemostasis and countering ATC. Whole blood, whether fresh or cold-stored, is emerging as a promising option to address multiple needs in traumatic hemorrhage. This review underscores the intricate relationships between oxygen debt, EoT, and ATC and highlights the importance of comprehensive, integrated strategies in the management of traumatic hemorrhage to prevent blood failure. A multidisciplinary approach is essential to address these interconnected factors effectively and to improve patient outcomes.

Design and Development of a Clot Burst Pressure Device to Investigate Resuscitation Strategies

INTRODUCTION

A reduction in clot strength is a hallmark feature of trauma-induced coagulopathy. A better understanding of clot integrity can optimize resuscitation strategies. We designed a device to gauge clot strength by pressurizing fluids over a formed clot and measuring the pressure needed to dislodge the clot. We hypothesized that this device could distinguish between clots formed in hypocoagulable and hypercoagulable states by observing differences in the clot burst pressure.

METHODS

Whole blood from healthy volunteers was collected into sodium citrate tubes and was treated with heparin or fibrinogen to generate clots in a hypocoagulable or hypercoagulable state, respectively. Small bore holes were drilled into polystyrene plates, and recalcified blood was pipetted into the holes. Plates were incubated at 37°C for 30 min to form clots. A pressure cap with an inlet for fluid from a syringe pump and an outlet leading to a measurement column was secured in the wells with a watertight seal.

RESULTS

Clot burst pressure was normalized to individual baseline values to account for inherent differences in clot strength. The 1.0 g/L and 2.0 g/L fibrinogen groups were 1.65 ± 0.07 (P = 0.0078) and 2.26 ± 0.16 (P = 0.0078) times as strong as baseline, respectively. The 0.10, 0.15, or 0.20 USP units/mL groups were 0.388 ± 0.07 (P = 0.125), 0.31 ± 0.07 (P = 0.125), 0.21 ± 0.07 (P = 0.125) times as strong as baseline, respectively. Data were analyzed using Wilcoxon matched pairs signed rank testing.

CONCLUSIONS

This device tests clot strength using burst pressure, an easily interpreted clinical parameter not measured in existing devices. Future work can test blood from trauma patients to better understand trauma pathophysiology.

Vasopressors in Trauma: A Never Event?

Vasopressor use in severely injured trauma patients is discouraged due to concerns that vasoconstriction will worsen organ perfusion and result in increased mortality and organ failure in hypotensive trauma patients. Hypotensive resuscitation is advocated based on limited data that lower systolic blood pressure and mean arterial pressure will result in improved mortality. It is classically taught that hypotension and hypovolemia in trauma are associated with peripheral vasoconstriction. However, the pathophysiology of traumatic shock is complex and involves multiple neurohormonal interactions that are ultimately manifested by an initial sympathoexcitatory phase that attempts to compensate for acute blood loss and is characterized by vasoconstriction, tachycardia, and preserved mean arterial blood pressure. The subsequent hypotension observed in hemorrhagic shock reflects a sympathoinhibitory vasodilation phase. The objectives of hemodynamic resuscitation in hypotensive trauma patients are restoring adequate intravascular volume with a balanced ratio of blood products, correcting pathologic coagulopathy, and maintaining organ perfusion. Persistent hypotension and hypoperfusion are associated with worse coagulopathy and organ function. The practice of hypotensive resuscitation would appear counterintuitive to the goals of traumatic shock resuscitation and is not supported by consistent clinical data. In addition, excessive volume resuscitation is associated with adverse clinical outcomes. Therefore, in the resuscitation of traumatic shock, it is necessary to target an appropriate balance with intravascular volume and vascular tone. It would appear logical that vasopressors may be useful in traumatic shock resuscitation to counteract vasodilation in hemorrhage as well as other clinical conditions such as traumatic brain injury, spinal cord injury, multiple organ dysfunction syndrome, and vasodilation of general anesthetics. The purpose of this article is to discuss the controversy of vasopressors in hypotensive trauma patients and advocate for a nuanced approach to vasopressor administration in the resuscitation of traumatic shock.

Absence of Adverse Neurological Outcomes in a Non-Neurologically Injured Polytrauma Patient Despite Extreme and Prolonged Treatment-Resistant Hypotension

Temporary hypotension after severe trauma might help achieve hemostasis and increase the chances of survival. However, excessive hypotension can lead to adverse neurological sequelae or be fatal. The relationship between the degree of hypotension and neurological prognosis after trauma is not fully understood. Our report describes a patient with severe trauma who survived with a favorable neurological outcome despite extreme and prolonged treatment-resistant hypotension.

Combination therapy using fibrinogen γ-chain peptide-coated, ADP-encapsulated liposomes and hemoglobin vesicles for trauma-induced massive hemorrhage in thrombocytopenic rabbits

BACKGROUND

We previously developed substitutes for red blood cells (RBCs) and platelets (PLTs) for transfusion. These substitutes included hemoglobin vesicles (HbVs) and fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, adenosine diphosphate (ADP)-encapsulated liposomes [H12-(ADP)-liposomes]. Here, we examined the efficacy of combination therapy using these substitutes instead of RBC and PLT transfusion in a rabbit model with trauma-induced massive hemorrhage with coagulopathy.

STUDY DESIGN AND METHODS

Thrombocytopenia (PLT count approximately 40,000/μL) was induced in rabbits by repeated blood withdrawal and isovolemic transfusion with autologous RBCs. Thereafter, lethal hemorrhage was induced in rabbits by noncompressible penetrating liver injury. Subsequently, H12-(ADP)-liposomes with platelet-poor plasma (PPP), platelet-rich plasma (PRP), or PPP alone were administered to stop bleeding. Once achieving hemostasis, HbVs, allogenic RBCs, or 5% albumin were transfused into rabbits to rescue them from fatal anemia following massive hemorrhage.

RESULTS

Administration of H12-(ADP)-liposomes/PPP as well as PRP (but not PPP) effectively stopped liver bleeding (100% hemostasis). The subsequent administration with HbVs as well as RBCs after hemostasis markedly rescued rabbits from fatal anemia (75% and 70% survivals for 24 hr, respectively). In contrast, 5% albumin administration rescued none of the rabbits.

CONCLUSION

Combination therapy with H12-(ADP)-liposomes and HbVs may be effective for damage control resuscitation of trauma-induced massive hemorrhage.

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.

Prehospital Blood Product Administration Opportunities in Ground Transport ALS EMS – A Descriptive Study

Introduction

Hemorrhage remains the major cause of preventable death after trauma. Recent data suggest that earlier blood product administration may improve outcomes. The purpose of this study was to determine whether opportunities exist for blood product transfusion by ground Emergency Medical Services (EMS).

Methods

This was a single EMS agency retrospective study of ground and helicopter responses from January 1, 2011 through December 31, 2015 for adult trauma patients transported from the scene of injury who met predetermined hemodynamic (HD) parameters for potential transfusion (heart rate [HR]≥120 and/or systolic blood pressure [SBP]≤90).

Results

A total of 7,900 scene trauma ground transports occurred during the study period. Of 420 patients meeting HD criteria for transfusion, 53 (12.6%) had a significant mechanism of injury (MOI). Outcome data were available for 51 patients; 17 received blood products during their emergency department (ED) resuscitation. The percentage of patients receiving blood products based upon HD criteria ranged from 1.0% (HR) to 5.9% (SBP) to 38.1% (HR+SBP). In all, 74 Helicopter EMS (HEMS) transports met HD criteria for blood transfusion, of which, 28 patients received prehospital blood transfusion. Statistically significant total patient care time differences were noted for both the HR and the SBP cohorts, with HEMS having longer time intervals; no statistically significant difference in mean total patient care time was noted in the HR+SBP cohort.

Conclusions

In this study population, HD parameters alone did not predict need for ED blood product administration. Despite longer transport times, only one-third of HEMS patients meeting HD criteria for blood administration received prehospital transfusion. While one-third of ground Advanced Life Support (ALS) transport patients manifesting HD compromise received blood products in the ED, this represented 0.2% of total trauma transports over the study period. Given complex logistical issues involved in prehospital blood product administration, opportunities for ground administration appear limited within the described system.

MixFM, ZielinskiMD, MyersLA, BernsKS, LukeA, StubbsJR, ZietlowSP, JenkinsDH, SztajnkrycerMD. Prehospital blood product administration opportunities in ground transport ALS EMS – a descriptive study. Prehosp Disaster Med. 2018;33(3):230–236.

Hypotensive Resuscitation with Hypertonic Saline Dextran Improves Survival in a Rat Model of Hemorrhagic Shock at High Altitude

OBJECTIVE

To compare the efficacy of hypotensive resuscitation with hypertonic saline dextran 70 (HSD) and lactated Ringer (LR) solutions in a rat model of hemorrhagic shock at a simulated altitude of 4,000 m.

METHODS

Anesthetized rats were bled to maintain their mean arterial pressure (MAP) at 45 mm Hg for 1 h. The distal quarter of the tail was then amputated to allow free blood loss; rats were simultaneously resuscitated with 4 mL kg HSD (HSD group, n = 10) or 4 mL kg LR (LR group, n = 10), followed by hypotensive resuscitation with LR to maintain MAP at 55 to 60 mm Hg for 1 h. A control group received no resuscitation (n = 10). Afterward, the cut end of the tail was ligated. The MAP, acid-base balance, blood loss, volume of fluid infused, and survival were recorded.

RESULTS

Compared with controls, HSD resuscitation improved MAP (without increasing uncontrolled blood loss), increased arterial pH and oxygen saturation (SaO2), decreased arterial lactate concentration at the end of resuscitation, and resulted in higher survival rate (P < 0.05). Hypotensive resuscitation with LR also maintained higher MAP, pH, and SaO2 than the control group, but was associated with increased blood loss and inferior survival (P > 0.05).

CONCLUSIONS

For hemorrhagic shock at simulated high altitude, resuscitation of rats with a bolus of HSD was associated with reduced blood loss and serum lactate concentration, and superior SaO2, hemoglobin concentration and survival rate, compared with LR solution.

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.

Effectiveness and Safety of Polygeline in Patients with Hypovolemia due to Trauma

Background:

This retrospective study examined the effectiveness and safety of polygeline in adult patients with hypovolemia due to traumatic injury.

Materials and Methods:

Polygeline was administered after evaluating the amount of blood loss and estimating hematological and biochemical parameters. Changes in vital signs, serum electrolytes, arterial pH, and serum lactate were evaluated. The safety was evaluated by recording the adverse events if any.

Results:

Sixty patients with the mean age 37.5 ± 11.26 years were included in the study. All patients had blood loss < 20%. The mean total polygeline administered was 1025.0 ± 464.18 ml. Blood transfusion was required in 3.33% of patients. Diastolic, systolic, and mean arterial blood pressure and pulse rate significantly increased after 1 h of polygeline administration (P < 0.0001). There was a trend toward increase in urine output (P = 0.0715) after 1 h. The improvement in vital parameters was consistent at 6, 14, and 18 h after administration of polygeline. Arterial pH significantly increased from 7.2 ± 0.12 to 7.3 ± 0.11 after 1 h of administration (P < 0.0001) and was consistent till 24 h (P = 0.035). Blood lactate decreased after 1 h (P < 0.0001). Changes in laboratory parameters were not clinically significant. After mean duration hospital stay of 10.5 ± 4.63 days all patients were discharged without any clinically significant abnormality or adverse event.

Conclusion:

Polygeline improved hemodynamic stability in patients with hypovolemia due to traumatic injury. The improvement was seen within 1 h (golden hour) of polygeline administration and maintained consistently. Polygeline can be safely administered to patients with traumatic injury to improve hemodynamic parameters and achieve stability.

Using the Reverse Shock Index at the Injury Scene and in the Emergency Department to Identify High-Risk Patients: A Cross-Sectional Retrospective Study

BACKGROUND

The ratio of systolic blood pressure (SBP) to heart rate (HR), called the reverse shock index (RSI), is used to evaluate the hemodynamic stability of trauma patients. A SBP lower than the HR (RSI < 1) indicates the probability of hemodynamic shock. The objective of this study was to evaluate whether the RSI as evaluated by emergency medical services (EMS) personnel at the injury scene (EMS RSI) and the physician in the emergency department (ED RSI) could be used as an additional variable to identify patients who are at high risk of more severe injury.

METHODS

Data obtained from all 16,548 patients added to the trauma registry system at a Level I trauma center between January 2009 and December 2013 were retrospectively reviewed. Only patients transferred by EMS were included in this study. A total of 3715 trauma patients were enrolled and subsequently divided into four groups: group I patients had an EMS RSI ≥1 and an ED RSI ≥1 (n = 3485); group II an EMS RSI ≥ 1 and an ED RSI < 1 (n = 85); group III an EMS RSI < 1 and an ED RSI ≥ 1 (n = 98); and group IV an EMS RSI < 1 and a ED RSI < 1 (n = 47). A Pearson's χ² test, Fisher's exact test, or independent Student's t-test was conducted to compare trauma patients in groups II, III, and IV with those in group I.

RESULTS

Group II and IV patients had a higher injury severity score, a higher incidence of commonly associated injuries, and underwent more procedures (including intubation, chest tube insertion, and blood transfusion in the ED) than patients in group I. Group II and IV patients were also more likely to receive a severe injury to the thoracoabdominal area. These patients also had worse outcomes regarding the length of stay in hospital and intensive care unit (ICU), the proportion of patients admitted to ICU, and in-hospital mortality. Group II patients had a higher adjusted odds ratio for mortality (5.8-times greater) than group I patients.

CONCLUSIONS

Using an RSI < 1 as a threshold to evaluate the hemodynamic condition of the patients at the injury scene and upon arrival to the ED provides valid information regarding deteriorating outcomes for certain subgroups of patients in the ED setting. Particular attention and additional resources should be provided to patients with an EMS RSI ≥ 1 that deteriorates to an RSI < 1 upon arrival to the ED since a higher odds of mortality was found in these patients.