A new survivable damage control model including hypothermia, hemodilution, and liver injury

Construction and validation of a novel and severe hepatic injury model in swine focuses on research and training. Observational study

Some hepatic wound models have been developed in pigs with the aim of reproducing liver injury; however, the wound shape, severity, and outcome differ among them. The novel injury profile employed in this study differed from that used elsewhere for standardized, repeatable, reproducible, incising-penetrating, vascular, and severe injury in swine. It is made with a cutting object that penetrates deep into the hepatic parenchyma, always affecting the two suprahepatic veins at the point where they merge into the common trunk. The primary outcome was reproducibility and replicability of the surgical method. The secondary outcome was the analysis of some variables (blood loss, survival, and flow) to validate the model. •This novel method of liver injury provides a liver injury with the following characteristics: standardized, incise-penetrated, deep, bloody, and severe.•This model can be used for research (trauma, hepato-bilio-pancreatic, pharmaceutical) and training (damage control surgery).•Method name: Incising-Penetrating, Vascular and Severe Liver Injury Model in Swine.

Utility of microporous polysaccharide hemospheres in severe hepatic trauma: Experimental study of hemostatic strength and ease of use

BACKGROUND

Animal studies confirm the utility of hemostatics against standard packing following severe liver injury. We investigated the efficacy and ease of use of novel microporous polysaccharide hemosphere (MPH) compounds (Perclot®, Baxter) in the treatment of severe hepatic hemorrhage in pig.

METHODS

Pigs were randomized to one of two equal treatment groups: MPH compounds (n=12) and Standard Packing (n=12). All animals underwent standardized surgical devascularization of the suprahepatic veins (grade V) to induce severe hepatic injury. Measures relating to the hemostatic success were monitored at 12, 60, 120 minutes and 24 hours post injury.

RESULTS

Animals allocated to treatment with MPH compounds were associated with higher survival rates at 24 hours than those undergoing standard packing: 66.7% vs, 0%, respectively (p=0.001). At 120 minutes MPH compounds were also associated with reduced blood loss, median (IQR) 1.16 (0.60) vs. 10.19 (5.77) mL/Kg, respectively: p<0.001) as well as higher invasive mean arterial pressures (iMAP) median (IQR) 39.12 (11.29) vs. 25.75 (14.28) mmHg, respectively: p=0.14) and hemoglobin levels median (IQR) 5.45 (2.50) vs. 6.45 (1.73) g/dL, respectively p=0.127). Overall, the application of MPH compounds required nearly half the time of standard packing median (IQR) 32.92 (6.51) vs. 67.75 (14.66) sec, respectively: p<0.001).

CONCLUSIONS

The data suggests that the use of MPH works in a severe hemorrhage in the liver of pigs, improving many variables in comparison to standard packing, including survival, blood loss and speed of application and we conclude that this offers a potential alternative for the treatment of hepatic injury. Further work is needed to corroborate these findings.

A novel inflatable device for perihepatic packing and hepatic hemorrhage control: A proof-of-concept study

INTRODUCTION

Uncontrolled bleeding is the primary cause of death in complex liver trauma and perihepatic packing is regularly utilized for hemorrhage control. The purpose of this study was to investigate the effectiveness of a novel inflatable device (the airbag) for perihepatic packing using a validated liver injury damage control model in swine.

MATERIAL AND METHODS

The image of the human liver was digitally isolated within an abdominal computerized tomography scan to produce a silicone model of the liver to mold the airbag. Two medical grade polyurethane sheets were thermal bonded to the configuration of the liver avoiding compression of the hepatic pedicle, hepatic veins, and the suprahepatic vena cava after inflation. Yorkshire pigs (n = 22) underwent controlled hemorrhagic shock (35% of the total blood volume), hypothermia, and fluid resuscitation to reproduce the indications for damage control surgery (coagulopathy, hypothermia, and acidosis) prior to a liver injury. A 3 × 10 cm rectangular segment of the left middle lobe of the liver was removed to create the injury. Subsequently, the animals were randomized into 4 groups for liver damage control (240 min), Sponge Pack (n = 6), Pressurized Airbag (n = 6), Vacuum Airbag (n = 6), and Uncontrolled (n = 4). Animals were monitored throughout the experiment and blood samples obtained.

RESULTS

Perihepatic packing with the pressurized airbag led to significantly higher mean arterial pressure during the liver damage control phase compared to sponge pack and vacuum airbag 52 mmHg (SD 2.3), 44.9 mmHg (SD 2.1), and 32 mmHg (SD 2.3), respectively (p < 0.0001), ejection fraction was also higher in that group. Hepatic hemorrhage was significantly lower in the pressurized airbag group compared to sponge pack, vacuum airbag, and uncontrolled groups; respectively 225 ml (SD 160), 611 ml (SD 123), 991 ml (SD 385), 1162 ml (SD 137) (p < 0001). Rebleeding after perihepatic packing removal was also significantly lower in the pressurized airbag group; respectively 32 ml (SD 47), 630 ml (SD 185), 513 ml (SD 303), (p = 0.0004). Intra-abdominal pressure remained similar to baseline, 1.9 mmHg (SD 1), (p = 0.297). Histopathology showed less necrosis at the border of the liver injury site with the pressurized airbag.

CONCLUSION

The pressurized airbag was significantly more effective at controlling hepatic hemorrhage and improving hemodynamics than the traditional sponge pack technique. Rebleeding after perihepatic packing removal was negligible with the pressurized airbag and it did not provoke hepatic injury.

Dried platelets in a swine model of liver injury

INTRODUCTION

Lyophilization may facilitate production of a safe, portable, easily storable, and transportable source of platelets for bleeding patients. The objective of this study was to examine the impact of lyophilized human and porcine platelets in a swine liver injury model of nonsurgical hemorrhage.

METHODS

Anesthetized pigs (40 kg) had a controlled 35% total blood volume bleed from the right jugular vein followed by cooling to 35°C and resuscitation with Ringer's lactate to achieve a 3:1 blood withdrawal resuscitation. Through a midline laparotomy, the liver was injured with two standardized 5 × 5-cm grids with lacerations 1 cm apart and 0.5 cm deep. After 2 min of uncontrolled hemorrhage, the animals were treated with placebo (n = 5), lyophilized human (n = 5, HP), or swine platelets (n = 5, SP). At 15 min, shed blood was calculated. The animals then underwent abdominal closure. At 48 h, the animals were killed for histopathologic evaluation of the lung, kidney, and heart.

RESULTS

Intraoperative blood loss at 15 min was significantly higher in the HP arm (SP: 4.9 ± 2.9 mL/kg, HP: 12.3 ± 4.7 mL/kg, and control: 6.1 ± 2.5 mL/kg; P = 0.013). Mortality at 48 h was 20% in all three arms, due to uncontrolled intra-abdominal bleeding. At the time the animals were killed, SP animals had a significantly higher hematocrit (SP: 22.0% ± 3.0%, HP: 15.1% ± 4.9%, and control: 13.9% ± 0.6%; P = 0.026). No significant difference was found in platelet count (SP: 319.3 ± 62.1 × 10(3)/µL, HP:361.5 ± 133.6 × 10(3)/µL, and control: 242.7 ± 42.5 × 10(3)/µL; P = 0.259). Histopathology of kidneys, lungs, and heart demonstrated no evidence of thromboembolic complications.

CONCLUSION

In this swine model of liver injury, human lyophilized platelets increased intraoperative blood loss. With the use of species-specific lyophilized platelets, however, this effect was abolished, with a decrease in blood loss at 48 h after injury.

Large animal evaluation of riboflavin and ultraviolet light-treated whole blood transfusion in a diffuse, nonsurgical bleeding porcine model

BACKGROUND

The Mirasol system has been demonstrated to effectively inactivate white blood cells (WBCs) and reduce pathogens in whole blood in vitro. The purpose of this study was to compare the safety and efficacy of Mirasol-treated fresh whole blood (FWB) to untreated FWB in an in vivo model of surgical bleeding.

STUDY DESIGN AND METHODS

A total of 18 anesthetized pigs (40 kg) underwent a 35% total blood volume bleed, cooling to 33°C, and a standardized liver injury. Animals were then randomly assigned to resuscitation with either Mirasol-treated or untreated FWB, and intraoperative blood loss was measured. After abdominal closure, the animals were observed for 14 days, after which the animals were euthanized and tissues were obtained for histopathologic examination. Mortality, tissue near-infrared spectroscopy, red blood cell (RBC) variables, platelets (PLTs), WBCs, and coagulation indices were analyzed.

RESULTS

Total intraoperative blood loss was similar in test and control arms (8.3 ± 3.2 mL/kg vs. 7.7 ± 3.9 mL/kg, p = 0.720). All animals survived to Day 14. Trended values over time did not show significant differences-tissue oxygenation (p = 0.605), hemoglobin (p = 0.461), PLTs (p = 0.807), WBCs (p = 0.435), prothrombin time (p = 0.655), activated partial thromboplastin time (p = 0.416), thromboelastography (TEG)-reaction time (p = 0.265), or TEG-clot formation time (p = 0.081). Histopathology did not show significant differences between arms.

CONCLUSIONS

Mirasol-treated FWB did not impact survival, blood loss, tissue oxygen delivery, RBC indices, or coagulation variables in a standardized liver injury model. These data suggest that Mirasol-treated FWB is both safe and efficacious in vivo.

Relevance of induced and accidental hypothermia after trauma-haemorrhage-what do we know from experimental models in pigs?

Recent experimental research has either focused on the role of accidental hypothermia as part of the lethal triad after trauma or tried to elucidate the effects of therapeutically induced hypothermia on the posttraumatic course. Induced hypothermia seems to reduce the mortality in experimental models of trauma-haemorrhage. As potential mechanisms, a decrease of cellular metabolism, beneficial effects on haemodynamic function and an attenuation of the inflammatory response have been described. However, negative side effects of hypothermia have to be considered, such as impairment of the coagulatory function and immunosuppressive effects. Furthermore, the optimal strategy for the induction of hypothermia (magnitude, duration, timing, cooling rate, etc.) and subsequent rewarming remains unclear. Nevertheless, this piece of information is essential before considering hypothermia as a treatment strategy for severely injured patients. This review aims to elaborate the differences between accidental and induced hypothermia and to summarize the current knowledge of the potential therapeutic use of induced hypothermia suggested in porcine models of trauma-haemorrhage.

Combined hemorrhage/trauma models in pigs-current state and future perspectives

The majority of injury combinations in multiply injured patients entail the chest, abdomen, and extremities. Numerous pig models focus on the investigation of posttraumatic pathophysiology, organ performance monitoring and on potential treatment options. Depending on the experimental question, previous authors have included isolated insults (controlled or uncontrolled hemorrhage, chest trauma) or a combination of these injuries (hemorrhage with abdominal trauma, chest trauma, traumatic brain injury, and/or long-bone fractures). Combined trauma models in pigs can provide a high level of clinical relevance, when they are properly designed and mimicking the clinical situation. Most of these models focus on the first hours after trauma, to assess the acute sequel of traumatic hemorrhage. However, hemorrhagic shock and the associated mass transfusion are also major causes for organ failure and mortality in the later clinical course. Thus, most models lack information on the pathomechanisms during the late posttraumatic phase. Studying new therapies only during the early phase is also not reflective of the clinical situation. Therefore, a longer observation period is required to study the effects of therapeutic approaches during intensive care treatment when using animal models. These long-term studies of combined trauma models will allow the development of valuable therapeutic approaches relevant for the later posttraumatic course. This review summarizes the existing porcine models and outlines the need for long-term models to provide real effective novel therapeutics for multiply injured patients to improve organ function and clinical outcome.