Intraperitoneal Metabolic Consequences of Supraceliac Aortic Balloon Occlusion in an Experimental Animal Study Using Microdialysis

Fully covered self‐expandable metal stent placed over a stapled colon anastomosis in an animal model: A pilot study of colon metabolism over the stent

Background and Aim

Anastomotic leakage (AL) in colorectal resection and primary anastomosis is a common and feared complication. Fully covered self‐expandable metal stents (FCSEMSs) have been used for the treatment of AL. It is still unknown whether FCSEMSs affect anastomosis healing negatively by causing ischemia. In an animal study, we investigated the metabolic effects over a FCSEMS covering a stapled colon anastomosis.

Methods

Seven pigs were investigated using microdialysis after laparotomy, colon resection, and anastomosis with stent placement. Measurements were done at the proximal and distal ends of the anastomosis and at a reference catheter placed at the small intestine. Measurements of glucose, pyruvate, lactate, glycerol, and the lactate/pyruvate ratio (L/P) were carried out.

Results

Lactate and L/P were significantly higher at the oral part of the anastomosis, while glucose showed a small declining tendency. At the distal part of the anastomosis, glucose decreased significantly after the resection but did not reach zero. Lactate increased significantly whereas L/P increased only slightly. Glycerol levels were stable.

Conclusion

Colon resection caused initially hypermetabolism in the intestinal ends next to the resection site. This hypermetabolism neither deteriorated nor turned into ischemia during the initial postoperative course, but the start of hypoxemia could not be excluded during the study and after the placement of an FCSEMS.

A Randomized Porcine Study in Low Cardiac Output of Vasoactive and Inotropic Drug Effects on the Gastrointestinal Tract

BACKGROUND

Splanchnic vasodilation by inodilators is an argument for their use in critical cardiac dysfunction. To isolate peripheral vasoactivity from inotropy, such drugs were investigated, and contrasted to vasopressors, in a fixed low cardiac output (CO) model resembling acute cardiac dysfunction effects on the gastrointestinal tract. We hypothesized that inodilators would vasodilate and preserve the aerobic metabolism in the splanchnic circulation in low CO.

METHODS

In anesthetized pigs, CO was lowered to 60% of baseline by partial inferior caval vein balloon inflation. The animals were randomized to placebo (n = 8), levosimendan (24 μg kg-1 bolus, 0.2 μg kg-1 min-1, n = 7), milrinone (50 μg kg-1 bolus, 0.5 μg kg-1 min-1, n = 7), vasopressin (0.001, 0.002 and 0.006 U kg-1 min-1, 1 h each, n = 7) or norepinephrine (0.04, 0.12, and 0.36 μg kg-1 min-1, 1 h each, n = 7). Hemodynamic variables including mesenteric blood flow were collected. Systemic, mixed-venous, mesenteric-venous, and intraperitoneal metabolites were analyzed.

RESULTS

Cardiac output was stable at 60% in all groups, which resulted in systemic hypotension, low superior mesenteric artery blood flow, lactic acidosis, and increased intraperitoneal concentrations of lactate. Levosimendan and milrinone did not change any circulatory variables, but levosimendan increased blood lactate concentrations. Vasopressin and norepinephrine increased systemic and mesenteric vascular resistances at the highest dose. Vasopressin increased mesenteric resistance more than systemic, and the intraperitoneal lactate concentration and lactate/pyruvate ratio.

CONCLUSION

Splanchnic vasodilation by levosimendan and milrinone may be negligible in low CO, thus rejecting the hypothesis. High-dose vasopressors may have side effects in the splanchnic circulation.

Resuscitative endovascular balloon occlusion of the aorta in combat casualties: The past, present, and future

BACKGROUND

Noncompressible torso hemorrhage is a leading cause of preventable death on the battlefield. Intra-aortic balloon occlusion was first used in combat in the 1950s, but military use was rare before Operation Iraqi Freedom and Operation Enduring Freedom. During these wars, the combination of an increasing number of deployed vascular surgeons and a significant rise in deaths from hemorrhage resulted in novel adaptations of resuscitative endovascular balloon occlusion of the aorta (REBOA) technology, increasing its potential application in combat. We describe the background of REBOA development in response to a need for minimally invasive intervention for hemorrhage control and provide a detailed review of all published cases (n = 47) of REBOA use for combat casualties. The current limitations of REBOA are described, including distal ischemia and reperfusion injury, as well as ongoing research efforts to adapt REBOA for prolonged use in the austere setting.

LEVEL OF EVIDENCE

Level V.

A randomized porcine study of the hemodynamic and metabolic effects of combined endovascular occlusion of the vena cava and the aorta in normovolemia and in hemorrhagic shock

BACKGROUND

Mortality from traumatic retrohepatic venous injuries is high and methods for temporary circulatory stabilization are needed. We investigated survival and hemodynamic and metabolic effects of resuscitative endovascular balloon occlusion of the aorta (REBOA) and vena cava inferior (REBOVC) in anesthetized pigs.

METHODS

Twenty-five anesthetized pigs in normovolemia or severe hemorrhagic shock (controlled arterial bleeding in blood bags targeting systolic arterial pressure of 50 mm Hg, corresponding to 40-50% of the blood volume) were randomized to REBOA zone 1 or REBOA+REBOVC zone 1 (n = 6-7/group) for 45 minutes occlusion, followed by 3-hour resuscitation and reperfusion. Hemodynamic and metabolic variables and markers of end-organ damage were measured regularly.

RESULTS

During occlusion, both the REBOA groups had higher systemic mean arterial pressure (MAP) and cardiac output (p < 0.05) compared with the two REBOA+REBOVC groups. After 60 minutes reperfusion, there were no statistically significant differences between the two REBOA groups and the two REBOA+REBOVC groups in MAP and cardiac output. The two REBOA+REBOVC groups had higher arterial lactate and potassium concentrations during reperfusion, compared with the two REBOA groups (p < 0.05). There was no major difference in end-organ damage markers between REBOA and REBOA+REBOVC. Survival after 1-hour reperfusion was 86% and 100%, respectively, in the normovolemic REBOA and REBOA+REBOVC groups, and 67% and 83%, respectively, in the corresponding hemorrhagic shock REBOA and REBOA+REBOVC groups.

CONCLUSION

Acceptable hemodynamic stability during occlusion and short-term survival can be achieved by REBOA+REBOVC with adequate resuscitation; however, the more severe hemodynamic and metabolic impacts of REBOA+REBOVC compared with REBOA must be considered.

LEVEL OF EVIDENCE

Prospective, randomized, experimental animal study. Basic science study, therapeutic.

Reperfusion repercussions: A review of the metabolic derangements following resuscitative endovascular balloon occlusion of the aorta

BACKGROUND

Current resuscitative endovascular balloon occlusion of the aorta (REBOA) literature focuses on improving outcomes through careful patient selection, diligent catheter placement, and expeditious definitive hemorrhage control. However, the detection and treatment of post-REBOA ischemia-reperfusion injury (IRI) remains an area for potential improvement. Herein, we provide a review of the metabolic derangements that we have encountered while managing post-REBOA IRI in past swine experiments. We also provide data-driven clinical recommendations to facilitate resuscitation post-REBOA deflation that may be translatable to humans.

METHODS

We retrospectively reviewed the laboratory data from 25 swine across three varying hemorrhagic shock models that were subjected to complete REBOA of either 45 minutes, 60 minutes, or 90 minutes. In each model the balloon was deflated gradually following definitive hemorrhage control. Animals were then subjected to whole blood transfusion and critical care with frequent electrolyte monitoring and treatment of derangements as necessary.

RESULTS

Plasma lactate peaked and pH nadired long after balloon deflation in all swine in the 45-minute, 60-minute, and 90-minute occlusion models (onset of peak lactate, 32.9 ± 6.35 minutes, 38.8 ± 10.55 minutes, and 49.5 ± 6.5 minutes; pH nadir, 4.3 ± 0.72 minutes, 26.9 ± 12.32 minutes, and 42 ± 7.45 minutes after balloon deflation in the 45-, 60-, and 90-minute occlusion models, respectively). All models displayed persistent hypoglycemia for more than an hour following reperfusion (92.1 ± 105.5 minutes, 125 ± 114.9 minutes, and 96 ± 97.8 minutes after balloon deflation in the 45-, 60-, and 90-minute occlusion groups, respectively). Hypocalcemia and hyperkalemia occurred in all three groups, with some animals requiring treatment more than an hour after reperfusion.

CONCLUSION

Metabolic derangements resulting from REBOA use are common and may worsen long after reperfusion despite resuscitation. Vigilance is required to detect and proactively manage REBOA-associated IRI. Maintaining a readily available "deflation kit" of pharmacological agents needed to treat common post-REBOA electrolyte abnormalities may facilitate management.

LEVEL OF EVIDENCE

Level V.

Early Metabolic and Inflammatory Intraperitoneal Changes After Rectum Perforation

Purpose

Anastomotic leakage (AL) is the most dreaded complication in rectal surgery. It has a great impact on postoperative morbidity and mortality. This animal model, in which we have studied postoperative metabolic and inflammatory changes, is designed to imitate an AL.

Methods

Twelve pigs were randomized into 2 groups. In the experimental group, an iatrogenic rectal perforation was performed, with the control group having a sham operation. The 2 groups were followed for 10 hours after operation with regard to vital parameters, arterial lactate, and cytokines interleukin (IL) 1, IL6, and IL10 in the blood and intraperitoneally. Intraperitoneal microdialysis analyses of glucose, lactate, glycerol, and pyruvate were performed and the lactate/pyruvate ratio was calculated.

Results

Glucose levels were lower in the experimental group after 4 hours. After 7 hours, lactate and lactate/pyruvate ratio was higher in the experimental group. At the same time intraperitoneal cytokines IL6 and IL10 were higher in the experimental group. Blood samples showed higher IL6 after 7 hours in the experimental group.

Conclusion

In this study, several significant differences between the groups in metabolic and inflammatory values were detected. Further clinical studies are recommended to evaluate the importance of intraperitoneal metabolic and inflammatory analyses as a diagnostic tool for early identification of an AL.

Results of postoperative microdialysis intraperitoneal and at the anastomosis in patients developing anastomotic leakage after rectal cancer surgery

Introduction: Anastomotic leakage postoperatively in patients operated with rectum resection and primary anastomosis is a common and feared complication. We have studied seven patients with an anastomotic leakage after surgery and compared them with 13 patients without complications.Methods: Metabolic measurements with microdialysis were done during the first seven postoperative days, with measurements of glucose, pyruvate, lactate and glycerol. The lactate/pyruvate ratio was calculated. Measurements were performed subcutaneously, intraperitoneally and at the anastomosis. The inflammatory cytokines, IL 6 and IL 10, were measured intravenously and intraperitoneally 48 hours postoperatively.Results: Intravenous and intraperitoneal IL 6 were higher in the leakage group. Around the small intestine (intraperitoneally), we found that patients developing anastomotic leakage had higher lactate and lactate/pyruvate ratio immediately after surgery. They also showed lower glycerol levels. At the anastomosis, we found higher lactate and lactate/pyruvate ratio in anastomotic leak patients after the fourth postoperative day.Conclusions: The results indicate that a possible mechanism behind an anastomotic leakage is an impaired circulation and thus insufficient saturation to the small intestine peroperatively. This develops into an inflammation both intraperitoneally and intravenously, which, if not reversed, spread within the gastrointestinal tract .The colorectal anastomosis is the most vulnerable part of the gastrointestinal tract postoperatively and hypoxia and inflammation may occur there, and an anastomosis leakage will be the consequence.

The 10 commandments of exsanguinating pelvic fracture management

Background:

Unstable pelvic fractures are highly lethal injuries.

Objective:

The review aims to summarize the landmark management changes in the past two decades.

Methods:

Structured review based on pertinent published literatures on severe pelvic fracture was performed.

Results:

Ten key management points were identified.

Conclusion:

These 10 recommendations help diminish and prevent the mortality. (1) Before the ABCDE management, preparedness, protection, and decision are essential to optimize patient outcome and to conserve resources. (2) Do not rock the pelvis to check stability, avoid logrolling but prophylactic pelvic binder can be life-saving. (3) Computed tomography scanner can be the tunnel to death for hemodynamically unstable patients. (4) Correct application of pelvic binder at the greater trochanter level to achieve the most effective compression. (5) Choose the suitable binder (BEST does not exist, always look for BETTER) to facilitate body examination and therapeutic intervention. (6) Massive transfusion protocol is only a temporizing measure to sustain the circulation for life maintenance. (7) Damage control operation aims to promptly stop the bleeding to restore the physiology by combating the trauma lethal triad to be followed by definitive anatomical repair. (8) Protocol-driven teamwork management expedites the completion of the multi-phase therapy including external pelvic fixation, pre-peritoneal pelvic packing, and angio-embolization, preceded by laparotomy when indicated. (9) Resuscitation endovascular balloon occlusion of aorta can reduce the pelvic bleeding while awaiting hospital transfer or operation theater access. (10) Operation is the definitive therapy for trauma but prevention is the best treatment, comprising primary, secondary, and tertiary levels.

Resuscitative Endovascular Balloon Occlusion of the Aorta: Review of the Literature and Applications to Veterinary Emergency and Critical Care

While hemorrhagic shock might be the result of various conditions, hemorrhage control and resuscitation are the corner stone of patient management. Hemorrhage control can prove challenging in both the acute care and surgical settings, especially in the abdomen, where no direct pressure can be applied onto the source of bleeding. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as a promising replacement to resuscitative thoracotomy (RT) for the management of non-compressible torso hemorrhage in human trauma patients. By inflating a balloon at specific levels (or zones) of the aorta to interrupt blood flow, hemorrhage below the level of the balloon can be controlled. While REBOA allows for hemorrhage control and augmentation of blood pressure cranial to the balloon, it also exposes caudal tissue beds to ischemia and the whole body to reperfusion injury. We aim to introduce the advantages of REBOA while reviewing known limitations. This review outlines a step-by-step approach to REBOA implementation, and discusses common challenges observed both in human patients and during translational large animal studies. Currently accepted and debated indications for REBOA in humans are discussed. Finally, we review possible applications for veterinary patients and how REBOA has the potential to be translated into clinical veterinary practice.

Perioperative intraperitoneal metabolic markers in patients undergoing cardiac surgery with cardiopulmonary bypass: an exploratory pilot study

Background:

Cardiopulmonary bypass and postoperative cardiac dysfunction cause splanchnic hypoperfusion resulting in intra-abdominal anaerobic metabolism and risk for gastrointestinal complications. The intra-abdominal metabolism can be monitored by intraperitoneal measurement of relevant metabolites using microdialysis. The aim of this study was to investigate the intraperitoneal metabolism using microdialysis during and after cardiopulmonary bypass at 34°C.

Methods:

In six patients undergoing elective coronary artery bypass grafting or aortic valve replacement under cardiopulmonary bypass, microdialysis was used to measure intraperitoneal and subcutaneous glucose, lactate, pyruvate, glycerol and glutamate concentrations, intraoperatively and up to 36 hours postoperatively. Arterial and central venous blood gases were analysed as were haemodynamics and the development of complications.

Results:

All patients had an ordinary perioperative course and did not develop gastrointestinal complications. The arterial, intraperitoneal and subcutaneous lactate concentrations changed during the perioperative course with differences between compartments. The highest median (interquartile range) concentration was recorded in the intraperitoneal compartment at 1 hour after the end of cardiopulmonary bypass (2.1 (1.9–2.5) mM compared to 1.3 (1.2–1.7) mM and 1.5 (1.0–2.2) mM in the arterial and subcutaneous compartments, respectively). In parallel with the peak increase in lactate concentration, the intraperitoneal lactate/pyruvate ratio was elevated to 33.4 (12.9–54.1).

Conclusion:

In cardiac surgery, intraperitoneal microdialysis detected changes in the abdominal metabolic state, which were more pronounced than could be shown by arterial blood gas analysis. Despite an uneventful perioperative course, patients undergoing low-risk surgery under cardiopulmonary bypass might be subjected to a limited and subclinical intra-abdominal anaerobic state.

Blood pressure targeting by partial REBOA is possible in severe hemorrhagic shock in pigs and produces less circulatory, metabolic and inflammatory sequelae than total REBOA

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an effective adjunct in exsanguinating torso hemorrhage, but causes ischemic injury to distal organs. The aim was to investigate whether blood pressure targeting by partial REBOA (pREBOA) is possible in porcine severe hemorrhagic shock and to compare pREBOA and total REBOA (tREBOA) regarding hemodynamic, metabolic and inflammatory effects.

METHODS

Eighteen anesthetized pigs were exposed to induced controlled hemorrhage to a systolic blood pressure (SBP) of 50 mmHg and randomized into three groups of thoracic REBOA: 30 min of pREBOA (target SBP 80-100 mmHg), tREBOA, and control. They were then resuscitated by autologous transfusion and monitored for 3 h. Hemodynamics, blood gases, mesenteric blood flow, intraperitoneal metabolites, organ damage markers, histopathology from the small bowel, and inflammatory markers were analyzed.

RESULTS

Severe hemorrhagic shock was induced in all groups. In pREBOA the targeted blood pressure was reached. The mesenteric blood flow was sustained in pREBOA, while it was completely obstructed in tREBOA. Arterial pH was lower, and lactate and troponin levels were significantly higher in tREBOA than in pREBOA and controls during the reperfusion period. Intraperitoneal metabolites, the cytokine response and histological analyses from the small bowel were most affected in the tREBOA compared to the pREBOA and control groups.

CONCLUSION

Partial REBOA allows blood pressure titration while maintaining perfusion to distal organs, and reduces the ischemic burden in a state of severe hemorrhagic shock. Partial REBOA may lower the risks of post-resuscitation metabolic and inflammatory impacts, and organ dysfunction.

Splanchnic Circulation and Intraabdominal Metabolism in Two Porcine Models of Low Cardiac Output

The impact of acute cardiac dysfunction on the gastrointestinal tract was investigated in anesthetized and instrumented pigs by sequential reductions of cardiac output (CO). Using a cardiac tamponade (n = 6) or partial inferior caval vein balloon inflation (n = 6), CO was controllably reduced for 1 h each to 75% (CO_75%), 50% (CO_50%), and 35% (CO_35%) of the baseline value. Cardiac output in controls (n = 6) was not manipulated and maintained. Mean arterial pressure, superior mesenteric arterial blood flow, and intestinal mucosal perfusion started to decrease at CO_50% in the intervention groups. The decrease in superior mesenteric arterial blood flow was non-linear and exaggerated at CO_35%. Systemic, venous mesenteric, and intraperitoneal lactate concentrations increased in the intervention groups from CO_50%. Global and mesenteric oxygen uptake decreased at CO_35%. In conclusion, gastrointestinal metabolism became increasingly anaerobic when CO was reduced by 50%. Anaerobic gastrointestinal metabolism in low CO can be detected using intraperitoneal microdialysis.

The pitfalls of resuscitative endovascular balloon occlusion of the aorta: Risk factors and mitigation strategies

Despite technological advancements, REBOA is associated with significant risks due to complications of vascular access and ischemia-reperfusion. The inherent morbidity and mortality of REBOA is often compounded by coexisting injury and hemorrhagic shock. Additionally, the potential for REBOA-related injuries is exaggerated due to the growing number of interventions being performed by providers who have limited experience in endovascular techniques, inadequate resources, minimal training in the technique, and who are performing this maneuver in emergency situations. In an effort to ultimately improve outcomes with REBOA, we sought to compile a list of complications that may be encountered during REBOA usage. To address the current knowledge gap, we assembled a list of anecdotal complications from high-volume REBOA users internationally. More importantly, through a consensus model, we identify contributory factors that may lead to complications and deliberate on how to recognize, mitigate, and manage such events. An understanding of the pitfalls of REBOA and strategies to mitigate their occurrence is of vital importance to optimize patient outcomes.

Pelvic trauma: WSES classification and guidelines

Complex pelvic injuries are among the most dangerous and deadly trauma related lesions. Different classification systems exist, some are based on the mechanism of injury, some on anatomic patterns and some are focusing on the resulting instability requiring operative fixation. The optimal treatment strategy, however, should keep into consideration the hemodynamic status, the anatomic impairment of pelvic ring function and the associated injuries. The management of pelvic trauma patients aims definitively to restore the homeostasis and the normal physiopathology associated to the mechanical stability of the pelvic ring. Thus the management of pelvic trauma must be multidisciplinary and should be ultimately based on the physiology of the patient and the anatomy of the injury. This paper presents the World Society of Emergency Surgery (WSES) classification of pelvic trauma and the management Guidelines.

A small case series of aortic balloon occlusion in trauma: lessons learned from its use in ruptured abdominal aortic aneurysms and a brief review

BACKGROUND

EndoVascular and Hybrid Trauma Management (EVTM) is an emerging concept for the early treatment of trauma patients using aortic balloon occlusion (ABO), embolization agents and stent grafts to stop ongoing traumatic bleeding. These techniques have previously been implemented successfully in the treatment of ruptured aortic aneurysm.

AIMS

We describe our very recent experience of EVTM using ABO in bleeding patients and lessons learned over the last 20 years from the endovascular treatment of ruptured abdominal aortic aneurysms (rAAA). We also briefly describe current knowledge of ABO usage in trauma.

METHODS

A small series of educational cases in our hospital is described, where endovascular techniques were used to gain temporary hemorrhage control. The methods used for rAAA and their applicability to EVTM with a multidisciplinary approach are presented.

RESULTS

Establishing femoral arterial access immediately on arrival at the emergency room and use of an angiography table in the surgical suite may facilitate EVTM at an early stage. ABO may be an effective method for the temporary stabilization of severely hemodynamically unstable patients with hemorrhagic shock, and may be useful as a bridge to definitive treatment of the bleeding patients.

CONCLUSION

EVTM, including the usage of ABO, can be initiated on patient arrival and is feasible. Further data need to be collected to investigate proper indications for ABO, best clinical usage, results and potential complications. Accordingly, the ABOTrauma Registry has recently been set up. Existing experiences of EVTM and lessons from the endovascular treatment of rAAA may be useful in trauma management.