Comparisons of lactated Ringer's and Hextend resuscitation on hemodynamics and coagulation following femur injury and severe hemorrhage in pigs

Assessment of ethynylestradiol-3-sulfate on coagulation, metabolism, and survival in pigs with traumatic hemorrhage

BACKGROUND

The beneficial effects of estrogens on survival from hemorrhage have been suggested in some preclinical models. This study investigated the effects of ethynylestradiol-3-sulfate (EE-3-S) on coagulation, metabolism and survival in pigs following traumatic hemorrhage.

METHODS

Twenty-six pigs were randomized into: normal saline group (NS, n = 10), EE-3-S group (EE-3, n = 11) groups, and no resuscitation group (NR, n = 5). Femur fracture was performed in each pig's left leg, followed by hemorrhage of 55% of estimated blood volume and a 10-minute shock period. Afterward, pigs were resuscitated with a small volume of either NS alone (4 mL/kg) or EE-3-S with NS (1 mL/kg at concentration of 1 mg/mL, plus NS solution of 3 mL/kg). Pigs in NR group were not resuscitated with any fluid. All pigs were then monitored for 6 hours or until death, with hemodynamics and survival times recorded. Blood samples were taken during the study for measurements of oxygen metabolism (oxygen delivery, extraction, and consumption) and coagulation function (using Rotem with Extem reagents).

RESULTS

All baseline measurements were similar among the three groups. In the NS group, femur fracture and hemorrhage immediately reduced mean arterial pressure (MAP, 74 ± 3 mm Hg to 44 ± 4 mm Hg) and increased heart rate (97 ± 5 bpm to 218 ± 14 bpm, both p < 0.05). Similar changes in MAP and heart rate were observed in the EE-3 and NR groups. There were no differences observed in changes of Rotem ® measurements or oxygen metabolism among the groups during the study. At 6 hours, four pigs in NS, four pigs in EE-3-S, and two pigs in the NR group survived to the end of the study. The mean survival times were similar among the NS (212 ± 43 minutes), EE-3 (212 ± 39 minutes), and NR (223 ± 63 minutes) groups ( p = 0.9845).

CONCLUSION

Following severe traumatic hemorrhage, hypotensive resuscitation with EE-3-S did not impact coagulation, metabolism, or survival in pigs.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Valproic Acid During Hypotensive Resuscitation In Pigs With Trauma And Hemorrhagic Shock Does Not Improve Survival

BACKGROUND

Valproic acid (VPA) has been extensively used for treatment of anxiety and seizure. Recent studies have shown that VPA has cellular protective effects in preclinical models following severe hemorrhage. This study investigated the effects of VPA on coagulation and survival in pigs after traumatic hemorrhage and hypotensive resuscitation.

METHODS

Following baseline measurements, femur fracture was performed in 20 anesthetized and instrumented pigs (41 ± 2 kg), followed by hemorrhage of 55% of the estimated blood volume and a 10 min shock period. Pigs were then resuscitated over 30 min with: normal saline alone (NS group, n = 10, 4 ml/kg) or VPA solution (VPA group, n = 10, 90 mg/kg, 2 ml/kg of 45 mg VPA/ml, plus 2 ml NS/kg). All pigs were then monitored for 2 hrs or until death. Hemodynamics were recorded and blood samples were taken for blood and coagulation analysis (Rotem®) at baseline, after hemorrhage, resuscitation, and 2 hrs or death.

RESULTS

Femur fracture and hemorrhage caused similar reductions in mean arterial pressure (MAP) and cardiac output and increase in heart rate in both groups. Resuscitation with NS or VPA did not return these measurements to baseline. No differences were observed in hematocrit, pH, lactate, base excess, or total protein between the groups. Compared to NS, resuscitation with VPA decreased platelet counts and prolonged aPTT, with no differences in fibrinogen levels, PT, or any of the Rotem® measurements between the two groups. Neither survival rates (NS: 7 of 10 pigs and VPA: 7 of 10 pigs) nor survival times after resuscitation (NS: 97 ± 40 min and VPA: 98 ± 43 min) differed between the groups.

CONCLUSIONS

Following traumatic hemorrhage and hypotensive resuscitation in pigs, VPA provides no benefit towards improving coagulation function or survival times.

LEVELS OF RELEVANCE

N/A.

Autoresuscitation of Poloxamer 188 in Pigs With Traumatic Severe Hemorrhage

BACKGROUND

Poloxamer 188 (P188) is a copolymer surfactant with plasma membrane stabilizing action. This study investigated the effects of P188 on blood volume and coagulation in pigs after traumatic hemorrhage and hypotensive resuscitation.

METHODS

Femur fracture was performed in 17 anesthetized pigs, followed by hemorrhage of 55% of estimated blood volume and a 10 min shock period. Afterwards, pigs were randomized to be resuscitated with either normal saline (n = 9, 4 mL/kg, NS group) or P188 (n = 8, 1.33 mL/kg at 150 mg/mL, plus 2.67 mL NS/kg, P188 group). Pigs were monitored for 2 h or until death. Hemodynamics were recorded and blood samples were taken at baseline (BL), after hemorrhage, shock, resuscitation, and at 2 h for blood and coagulation analysis using Rotem®.

RESULTS

All but one pig in each group survived to 2 h. Femur fracture and hemorrhage reduced mean arterial pressure to half of the BL and elevated heart rate to double of the BL (both P < 0.05). Resuscitation with NS or P188 did not return these measurements to BL. Compared to NS, resuscitation with P188 resulted in a smaller reduction of blood volume (76 ± 3% in P188 and 60 ± 2% in NS); higher base excess (3.3 ± 0.9 vs. 0.5 ± 0.9 mM); and lower hematocrit (24 ± 1 vs. 28 ± 1%) and Ca++ (24 ± 1 vs. 28 ± 1 mM). Resuscitation with P188 prolonged aPTT (43 ± 12 vs. 22 ± 3 s, all P < 0.05).

CONCLUSIONS

Following traumatic hemorrhage and hypotensive resuscitation, P188 improved circulation volume and base deficit, but induced slower clotting initiation in pigs. Thus, P188 may have limited benefit as an initial small volume resuscitation adjunct following hemorrhage.

Should we change our approach to resuscitating victims of femoral fracture? A clinical experience in a busy trauma hospital in Shiraz, Iran

PURPOSE

Traumatic hemorrhagic shock is a life-threatening event worldwide. Severe brain trauma accompanying femoral fractures can trigger inflammatory responses in the body and increase pre-inflammatory cytokines such as TNF-α, IL-1. The primary treatment in these cases is hydration with crystalloids, which has both benefits and complications. The purpose of this study was to investigate the effects of fluid therapy on the hemodynamics, coagulation profiles, and blood gases in such patients.

METHODS

In this cross-sectional study, patients were divided into two groups: femoral fracture group and non-femoral group. The hemodynamic status, coagulation profile, and blood gases of patients in both groups were evaluated upon arrival at the hospital and again 2 h later. Data were analyzed by t-test and ANOVA with repeated data and paired samples t-test.

RESULTS

A total of 681 trauma patients (605 men and 76 women) participated in this study, including 69 (86.3%) men and 11 (13.8%) women in femoral fracture group and 536 men (89.2%) and 65 women (10.8%) in non-femoral group. The laboratory parameters were evaluated in response to the equal amount of crystalloid fluid given upon arrival and 2 h later. Blood gases decreased in the fracture group despite fluid therapy (p < 0.003), and the coagulation profile worsened although the change was not statistically significant.

CONCLUSION

The treatment of multiple-trauma patients with femoral bone fractures should be more concerned with the need for the infusion of vasopressors such as norepinephrine. If there is evidence of clinical shock, excessive crystalloid infusion (limited to 1 L) should be avoided, and blood and blood products should be started as soon as possible.

Efficacy of resuscitation with fibrinogen concentrate and platelets in traumatic hemorrhage swine model

BACKGROUND

This study compared the resuscitation effects of platelets and fibrinogen concentrate (FC) on coagulation and hemodynamics in pigs with traumatic hemorrhage and reduced platelet counts.

METHODS

Thirty pigs (40 ± 3 kg) were anesthetized and catheterized with an apheresis catheter to remove platelets using the Haemonetics 9000 (Haemonetics, Braintree, MA). Afterward, a femur fracture was induced, followed by hemorrhage of 35% the estimated blood volume. Pigs were then randomized to be resuscitated with 5% human albumin (12.5 mL/kg), FC (250 mg/kg, 12.5 mL/kg), or platelets collected from apheresis (11.0 ± 0.5 mL/kg). Animals were monitored for 2 hours or until death. Blood samples were collected before (baseline [BL]) and after apheresis, after hemorrhage, and after resuscitation to assess changes in hemodynamics and coagulation using Rotem.

RESULTS

No change in mean arterial pressure (MAP) or heart rate (HR) was observed by platelet apheresis. Hemorrhage reduced MAP to 57% ± 5% and elevated HR to 212% ± 20% of BL (both p < 0.05). Resuscitation with albumin, FC, or platelets did not revert MAP or HR to BL. Platelet counts were reduced by apheresis from BL 383 ± 20 × 10/μL to 141 ± 14 × 10/μL and were reduced further after resuscitation with albumin (88 ± 18 × 10/μL) or FC (97 ± 13 × 10/μL, all p < 0.05), but improved with platelet resuscitation (307 ± 24 × 10/μL). Fibrinogen concentration was reduced by apheresis from BL 225 ± 9 mg/dL to 194 ± 8 mg/dL, fell after albumin infusion (134 ± 11 mg/dL), increased to 269 ± 10 mg/dL after FC resuscitation (all p < 0.05), and was not affected by platelet resuscitation. Rotem α-angle decreased from 79 ± 2 degrees to 69 ± 1 degrees by apheresis and hemorrhage (p < 0.05), and recovered similarly by resuscitation with FC (87 ± 1 degrees) or platelets (78 ± 2 degrees), but not by albumin (63 ± 3 degrees). Similar responses were observed in Rotem maximum clot firmness.

CONCLUSION

In this traumatic hemorrhage swine model, low-volume resuscitation with FC or platelets was similarly effective in restoring coagulation.

Mean arterial pressure targeted fluid resuscitation may lead to fluid overload: A bleeding-resuscitation animal experiment

Introduction

Fluid resuscitation is the cornerstone of treatment in hemorrhagic shock. Despite increasing doubts, several guidelines recommend to maintain mean arterial pressure (MAP) >65 mmHg as the most frequent indication of fluid therapy. Our aim was to investigate the effects of a MAP-guided management in a bleeding-resuscitation animal experiment.

Materials and methods

After anesthesia and instrumentation (t_bsl) animals were bled till the initial stroke volume index dropped by 50% (t₀). Fluid replacement was performed in 4 equivalent steps (t_1-4) with balanced crystalloid solution to reach the baseline values of MAP. Invasive hemodynamic measurements and blood gas analyses were performed after each step.

Results

Mean arterial pressure dropped from t_bsl to t₀ (114±11 vs 76.9±16.9 mmHg, p<0.001) and returned to baseline by t₄ (101.4±14.4 mmHg). From t_bsl-t₀ stroke volume index (SVI), cardiac index (CI) decreased (SVI: 40±8.6 vs 19.3±3.6 ml/m², p<0.001; CI: 3.4±0.3 vs 1.9±0.3 l/min/m², p<0.001), pulse pressure variation (PPV) increased (13.2±4.3 vs 22.1±4.3%, p<0.001). There was a decrease in oxygen delivery (464±45 vs 246±26.9 ml/min, p<0.001), central venous oxygen saturation (82.8±5.4 vs 53.6±12.1%, p<0.001) and increase in lactate levels (1.6±0.4 vs 3.5±1.6 mmol/l, p<0.005). SVI, CI and PPV returned to their initial values by t₂. To normalize MAP fluid therapy had to be continued till t₄, with the total infused volume of 4.5±0.8 l.

Conclusion

In the current experiment bleeding led to hemorrhagic shock, while MAP remained higher than 65 mmHg. Furthermore, MAP was unable to indicate the normalization of SVI, CI and PPV that resulted in unnecessary fluid administration. Our data give further evidence that MAP may be an inappropriate parameter to follow during fluid resuscitation.

Coagulation complications following trauma

Traumatic injury is one of the leading causes of death, with uncontrolled hemorrhage from coagulation dysfunction as one of the main potentially preventable causes of the mortality. Hypothermia, acidosis, and resuscitative hemodilution have been considered as the significant contributors to coagulation manifestations following trauma, known as the lethal triad. Over the past decade, clinical observations showed that coagulopathy may be present as early as hospital admission in some severely injured trauma patients. The hemostatic dysfunction is associated with higher blood transfusion requirements, longer hospital stay, and higher mortality. The recognition of this early coagulopathy has initiated tremendous interest and effort in the trauma community to expand our understanding of the underlying pathophysiology and improve clinical treatments. This review discusses the current knowledge of coagulation complications following trauma.

A Comparison of the Effects of Intraosseous and Intravenous 5% Albumin on Infusion Time and Hemodynamic Measures in a Swine Model of Hemorrhagic Shock

Introduction Obtaining intravenous (IV) access in patients in hemorrhagic shock is often difficult and prolonged. Failed IV attempts delay life-saving treatment. Intraosseous (IO) access may often be obtained faster than IV access. Albumin (5%) is an option for prehospital volume expansion because of the absence of interference with coagulation and platelet function. Hypothesis/Problem There are limited data comparing the performance of IO and IV administered 5% albumin. The aims of this study were to compare the effects of tibial IO (TIO) and IV administration of 500 mL of 5% albumin on infusion time and hemodynamic measurements of heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) in a swine model of hemorrhagic shock.

METHODS

Sixteen male swine were divided into two groups: TIO and IV. All subjects were anesthetized and a Class III hemorrhage was achieved by exsanguination of 31% of estimated blood volume (EBV) from a femoral artery catheter. Following exsanguination, 500 mL of 5% albumin was administered under pressurized infusion (300 mmHg) by the TIO or IV route and infusion time was recorded. Hemodynamic measurements of HR, MAP, CO, and SV were collected before and after exsanguination and every 20 seconds for 180 seconds during 5% albumin infusion.

RESULTS

An independent t-test determined that IV 5% albumin infusion was significantly faster compared to IO (P=.01). Mean infusion time for TIO was seven minutes 35 seconds (SD=two minutes 44 seconds) compared to four minutes 32 seconds (SD=one minute 08 seconds) in the IV group. Multivariate Analysis of Variance was performed on hemodynamic data collected during the 5% albumin infusion. Analyses indicated there were no significant differences between the TIO and IV groups relative to MAP, CO, HR, or SV (P>.05).

CONCLUSION

While significantly longer to infuse 5% albumin by the TIO route, the longer TIO infusion time may be negated as IO devices can be placed more quickly compared to repeated IV attempts. The lack of significant difference between the TIO and IV routes relative to hemodynamic measures indicate the TIO route is a viable route for the infusion of 5% albumin in a swine model of Class III hemorrhage. Muir SL , Sheppard LB , Maika-Wilson A , Burgert JM , Garcia-Blanco J , Johnson AD , Coyner JL . A comparison of the effects of intraosseous and intravenous 5% albumin on infusion time and hemodynamic measures in a swine model of hemorrhagic shock. Prehosp Disaster Med. 2016;31(4):436-442.

Fibrinogen concentrate administration inhibits endogenous fibrinogen synthesis in pigs after traumatic hemorrhage

BACKGROUND

Fibrinogen plays a central role in coagulation and falls to critical levels early after trauma. Administration of fibrinogen concentrate (FC) to improve hemostasis after severe bleeding seems beneficial, but it is unclear whether its use introduces excessive fibrinogen with a potential risk of thrombosis. This study investigated changes of endogenous fibrinogen metabolism from FC administration following traumatic hemorrhage in pigs.

METHODS

Anesthetized, instrumented pigs were randomized into lactated Ringer's (LR) solution only and LR plus FC groups (n = 7 each). Femur fracture of each pig's left leg was followed by hemorrhage of 60% total blood volume and resuscitation with LR (3× bled volume, LR group) or LR plus FC at 250 mg/kg (LR-FC group). Afterward, a constant infusion of stable isotopes 1-C-phenylalanine (phe, 6 hours) and d5-phe (3 hours) was performed with hourly blood sampling and subsequent gas chromatography-mass spectrometry analysis to quantify fibrinogen synthesis and breakdown rates, respectively. Blood gas and coagulation indices (thromboelastography) were measured on intermittent blood samples, and hemodynamics was continuously monitored. Animals were euthanized after the 6-hour isotope period.

RESULTS

Mean arterial pressure decreased by 50% after hemorrhage but improved after LR resuscitation in both groups. Hemorrhage and LR resuscitation reduced total protein, hematocrit, fibrinogen, and platelets to 50% of baseline values. Moreover, hemorrhage and resuscitation decreased fibrinogen concentration (207 ± 6 vs. 132 ± 7 mg/dL) and clot strength (72 ± 2 vs. 63 ± 2 mm) in both groups (p < 0.05). FC administration restored plasma fibrinogen concentrations and clot strength within 15 minutes, while no changes occurred in the LR group. Fibrinogen synthesis rates in the LR-FC group (1.3 ± 0.2 mg/kg/h) decreased versus the LR group (3.1 ± 0.5; p < 0.05), whereas fibrinogen breakdown rates were similar.

CONCLUSION

Our data suggest an effective feedback mechanism that regulates host fibrinogen availability and thereby suggests that acute thrombosis from FC administration is an unlikely risk.

The ebb and flow of fluid (as in resuscitation)

Since the early 1960's "resuscitation" following major trauma involved use of replacement crystalloid fluid/estimated blood loss in volumes of 3/1, in the ambulance, emergency room, operating room and surgical intensive care unit. During the past 20 years, MAJOR paradigm shifts have occurred in this concept. As a result hypotensive resuscitation with a view towards restriction of crystalloid, and prevention of complications has occurred. Improved results in both civilian and military environments have been reported. As a result there is new focus on trauma surgical involvement in all aspects of trauma patient management, focus on early aggressive surgical approaches (which may or may not involve an operation), and movement from crystalloid to blood, plasma, and platelet replacement therapy.

Comparisons of normal saline and lactated Ringer's resuscitation on hemodynamics, metabolic responses, and coagulation in pigs after severe hemorrhagic shock

Background

Ongoing improvements in trauma care now recommend earlier use of blood products as part of damage control resuscitation, but generally these products are not available at far forward battlefield locations. For the military, questions continue to arise regarding efficacy of normal saline (NS) vs. lactated Ringer’s (LR). Thus, this study compared the effects of LR and NS after severe hemorrhage in pigs.

Methods

20 anesthetized pigs were randomized into control (n = 6), LR (n = 7), and NS (n = 7) groups. Hemorrhage of 60% estimated total blood volume was induced in LR and NS groups by removing blood from the left femoral artery using a computer-controlled pump. Afterwards, the pigs were resuscitated with either LR at 3 times the bled volume or the volume of NS to reach the same mean arterial pressure (MAP) as in LR group. Hemodynamics were measured hourly and blood samples were taken at baseline (BL), 15 min, 3 h and 6 h after resuscitation to measure changes in coagulation using thrombelastograph®.

Results

MAP was decreased by hemorrhage but returned to BL within 1 h after resuscitation with LR (119 ± 7 ml/kg) or NS (183 ± 9 ml/kg, p < 0.05). Base excess (BE) was decreased by hemorrhage; resuscitation with LR recovered BE but not with NS. Total peripheral resistance was decreased with NS and LR, with a larger drop shown in NS. Serum potassium was increased with NS, but not affected with LR. Coagulation changes were similar between LR and NS.

Conclusions

NS may be inferior to LR in resuscitation due to its vasodilator effects and the risks of metabolic acidosis and hyperkalemia.