Gastroesophageal resuscitative occlusion of the aorta prolongs survival in a lethal liver laceration model

BACKGROUND

Noncompressible torso hemorrhage management remains a challenge especially in the prehospital setting. We evaluated a device designed to occlude the aorta from the stomach (gastroesophageal resuscitative occlusion of the aorta [GROA]) for its ability to stop hemorrhage and improve survival in a swine model of lethal liver laceration and compared its performance to resuscitative endovascular balloon occlusion of the aorta (REBOA) and controls.

METHODS

Swine (n = 24) were surgically instrumented and a 30% controlled arterial hemorrhage over 20 minutes was followed by liver laceration. Animals received either GROA, REBOA, or control (no treatment) for 60 minutes. Following intervention, devices were deactivated, and animals received whole blood and crystalloid resuscitation. Animals were monitored for an additional 4 hours.

RESULTS

The liver laceration resulted in the onset of class IV shock. Mean arterial blood pressure (MAP) (standard deviation) decreased from 84.5 mm Hg (11.69 mm Hg) to 27.1 mm Hg (5.65 mm Hg) at the start of the intervention. Seven of eight control animals died from injury prior to the end of the intervention period with a median survival (interquartile) time of 10.5 minutes (12 minutes). All GROA and REBOA animals survived the duration of the intervention period (60 minutes) with median survival times of 86 minutes (232 minutes) and 79 minutes (199 minutes) after resuscitation, respectively. The GROA and REBOA animals experienced a significant improvement in survival compared with controls (p = 0.01). Resuscitative endovascular balloon occlusion of the aorta resulted in higher MAP at the end of intervention 114.6 mm Hg (22.9 mm Hg) compared with GROA 88.2 mm Hg (18.72 mm Hg) (p = 0.024), as well as increased lactate compared with GROA 13.2 meq·L-1 (1.56 meq·L-1) versus 10.5 meq·L-1 (1.89 meq·L-1) (p = 0.028). Histological examination of the gastric mucosa in surviving animals revealed mild ischemic injury from both GROA and REBOA.

CONCLUSION

The GROA and REBOA devices were both effective at temporarily stanching lethal noncompressible torso hemorrhage of the abdomen and prolonging survival.

Novel intraperitoneal hemostasis device prolongs survival in a swine model of noncompressible abdominal hemorrhage

BACKGROUND

Noncompressible torso hemorrhage (NCTH) of the abdomen is a challenge to rapidly control and treat in the prehospital and emergency department settings. In this pilot study, we developed a novel intraperitoneal hemostasis device (IPHD) prototype and evaluated its ability for slowing NCTH and prolonging survival in a porcine model of lethal abdominal multiorgan hemorrhage.

METHODS

Yorkshire male swine (N = 8) were instrumented under general anesthesia for monitoring of hemodynamics and blood sampling. Animals were subjected to a 30% controlled arterial hemorrhage followed by lacerating combinations of the liver, spleen, and kidney. The abdomen was closed and after 2 minutes of NCTH, and the IPHD was inserted into the peritoneal cavity via an introducer (n = 5). The balloon was inflated and maintained for 60 minutes. At 60 minutes postdeployment, the balloon was deflated and removed, and blood resuscitation was initiated followed by gauze packing for hemostasis. The remaining animals (n = 3) were used as controls and subjected to the same injury without intervention.

RESULTS

All animals managed with IPHD intervention (5 of 5 swine) survived the duration of the intervention period (60 minutes), while all control animals (3 of 3 swine) died at a time range of 15 to 43 minutes following organ injury (p = 0.0042). Animals receiving IPHD remained hemodynamically stable with a mean arterial pressure range of 44.86 to 55.10 mm Hg and experienced increased cardiac output and decreased shock index after treatment. Controls experienced hemodynamic decline in all parameters until endpoints were met. Upon IPHD deflation and removal, all treated animals began to hemorrhage again and expired within 2 to 132 minutes despite packing.

CONCLUSION

Our data show that the IPHD concept is capable of prolonging survival by temporarily stanching lethal NCTH of the abdomen. This device may be an effective temporary countermeasure to NCTH of the abdomen that could be deployed in the prehospital environment or as a bridge to more advanced therapy.

A novel swine model of the acute respiratory distress syndrome using clinically relevant injury exposures

To date, existing animal models of the acute respiratory distress syndrome (ARDS) have failed to translate preclinical discoveries into effective pharmacotherapy or diagnostic biomarkers. To address this translational gap, we developed a high-fidelity swine model of ARDS utilizing clinically relevant lung injury exposures. Fourteen male swine were anesthetized, mechanically ventilated, and surgically instrumented for hemodynamic monitoring, blood, and tissue sampling. Animals were allocated to one of three groups: (1) Indirect lung injury only: animals were inoculated by direct injection of Escherichia coli into the kidney parenchyma, provoking systemic inflammation and distributive shock physiology; (2) Direct lung injury only: animals received volutrauma, hyperoxia, and bronchoscope-delivered gastric particles; (3) Combined indirect and direct lung injury: animals were administered both above-described indirect and direct lung injury exposures. Animals were monitored for up to 12 h, with serial collection of physiologic data, blood samples, and radiographic imaging. Lung tissue was acquired postmortem for pathological examination. In contrast to indirect lung injury only and direct lung injury only groups, animals in the combined indirect and direct lung injury group exhibited all of the physiological, radiographic, and histopathologic hallmarks of human ARDS: impaired gas exchange (mean PaO₂ /FiO₂ ratio 124.8 ± 63.8), diffuse bilateral opacities on chest radiographs, and extensive pathologic evidence of diffuse alveolar damage. Our novel porcine model of ARDS, built on clinically relevant lung injury exposures, faithfully recapitulates the physiologic, radiographic, and histopathologic features of human ARDS and fills a crucial gap in the translational study of human lung injury.

Aerosol generation during chest compression and defibrillation in a swine cardiac arrest model

Aim

It remains unclear whether cardiac arrest (CA) resuscitation generates aerosols that can transmit respiratory pathogens. We hypothesize that chest compression and defibrillation generate aerosols that could contain the SARS-CoV-2 virus in a swine CA model.

Methods

To simulate witnessed CA with bystander-initiated cardiopulmonary resuscitation, 3 female non-intubated swine underwent 4 min of ventricular fibrillation without chest compression or defibrillation (no-flow) followed by ten 2-min cycles of mechanical chest compression and defibrillation without ventilation. The diameter (0.3–10 μm) and quantity of aerosols generated during 45-s intervals of no-flow and chest compression before and after defibrillation were analyzed by a particle analyzer. Aerosols generated from the coughs of 4 healthy human subjects were also compared to aerosols generated by swine.

Results

There was no significant difference between the total aerosols generated during chest compression before defibrillation compared to no-flow. In contrast, chest compression after defibrillation generated significantly more aerosols than chest compression before defibrillation or no-flow (72.4 ± 41.6 × 10⁴ vs 12.3 ± 8.3 × 10⁴ vs 10.5 ± 11.2 × 10⁴; p < 0.05), with a shift in particle size toward larger aerosols. Two consecutive human coughs generated 54.7 ± 33.9 × 10⁴ aerosols with a size distribution smaller than post-defibrillation chest compression.

Conclusions

Chest compressions alone did not cause significant aerosol generation in this swine model. However, increased aerosol generation was detected during chest compression immediately following defibrillation. Additional research is needed to elucidate the clinical significance and mechanisms by which aerosol generation during chest compression is modified by defibrillation.

A comprehensive assessment of multi-system responses to a renal inoculation of uropathogenic E. coli in swine

BACKGROUND

The systemic responses to infection and its progression to sepsis remains poorly understood. Progress in the field has been stifled by the shortcomings of experimental models which include poor replication of the human condition. To address these challenges, we developed and piloted a novel large animal model of severe infection that is capable of generating multi-system clinically relevant data.

METHODS

Male swine (n = 5) were anesthetized, mechanically ventilated, and surgically instrumented for continuous hemodynamic monitoring and serial blood sampling. Animals were inoculated with uropathogenic E. coli by direct injection into the renal parenchyma and were maintained until a priori endpoints were met. The natural history of the infection was studied. Animals were not resuscitated. Multi-system data were collected hourly to 6 hours; all animals were euthanized at predetermined physiologic endpoints.

RESULTS

Core body temperature progressively increased from mean (SD) 37.9(0.8)°C at baseline to 43.0(1.2)°C at experiment termination (p = 0.006). Mean arterial pressure did not begin to decline until 6h post inoculation, dropping from 86(9) mmHg at baseline to 28(5) mmHg (p = 0.005) at termination. Blood glucose progressively declined but lactate levels did not elevate until the last hours of the experiment. There were also temporal changes in whole blood concentrations of a number of metabolites including increases in the catecholamine precursors, tyrosine (p = 0.005) and phenylalanine (p = 0.005). Lung, liver, and kidney function parameters worsened as infection progressed and at study termination there was histopathological evidence of injury in these end-organs.

CONCLUSION

We demonstrate a versatile, multi-system, longitudinal, swine model of infection that could be used to further our understanding of the mechanisms that underlie infection-induced multi-organ dysfunction and failure, optimize resuscitation protocols and test therapeutic interventions. Such a model could improve translation of findings from the bench to the bedside, circumventing a significant obstacle in sepsis research.

Dose optimization of early high-dose valproic acid for neuroprotection in a swine cardiac arrest model

Aim

High-dose valproic acid (VPA) improves the survival and neurologic outcomes after asphyxial cardiac arrest (CA) in rats. We characterized the pharmacokinetics, pharmacodynamics, and safety of high-dose VPA in a swine CA model to advance clinical translation.

Methods

After 8 ​min of untreated ventricular fibrillation CA, 20 male Yorkshire swine were resuscitated until return of spontaneous circulation (ROSC). They were block randomized to receive placebo, 75 ​mg/kg, 150 ​mg/kg, or 300 ​mg/kg VPA as 90-min intravenous infusion (n ​= ​5/group) beginning at ROSC. Animals were monitored for 2 additional hours then euthanized. Experimental operators were blinded to treatments.

Results

The mean(SD) total CA duration was 14.8(1.2) minutes. 300 ​mg/kg VPA animals required more adrenaline to maintain mean arterial pressure ≥80 ​mmHg and had worse lactic acidosis. There was a strong linear correlation between plasma free VPA C_max and brain total VPA (r² ​= ​0.9494; p ​< ​0.0001). VPA induced dose-dependent increases in pan- and site-specific histone H3 and H4 acetylation in the brain. Plasma free VPA C_max is a better predictor than peripheral blood mononuclear cell histone acetylation for brain H3 and H4 acetylation (r² ​= ​0.7189 for H3K27ac, r² ​= ​0.7189 for pan-H3ac, and r² ​= ​0.7554 for pan-H4ac; p ​< ​0.0001).

Conclusions

Up to 150 ​mg/kg VPA can be safely tolerated as 90-min intravenous infusion in a swine CA model. High-dose VPA induced dose-dependent increases in brain histone H3 and H4 acetylation, which can be predicted by plasma free VPA C_max as the pharmacodynamics biomarker for VPA target engagement after CA.