Whole Blood Selective Aortic Arch Perfusion for Exsanguination Cardiac Arrest: Assessing Myocardial Tolerance to the Duration of Cardiac Arrest.

INTRODUCTION: Selective aortic arch perfusion (SAAP) is an endovascular technique that consists of aortic occlusion with perfusion of the coronary and cerebral circulation. It been shown to facilitate return of spontaneous circulation (ROSC) after exanguination cardiac arrest (ECA), but it is not known how long arrest may last before the myocardium can no longer be durably recovered. The aim of this study is to assess the myocardial tolerance to exsanguination cardiac arrest before successful ROSC with SAAP. METHODS: Male adult swine (n = 24) were anesthetized, instrumented, and hemorrhaged to arrest. Animals were randomized into three groups: 5, 10, and 15 min of cardiac arrest before resuscitation with SAAP. Following ROSC, animals were observed for 60 min in a critical care environment. Primary outcomes were ROSC, and survival at 1-h post-ROSC. RESULTS: Shorter cardiac arrest time was associated with higher ROSC rate and better 1-h survival. ROSC was obtained for 100% (8/8) of the 5-min ECA group, 75% (6/8) of the 10-min group, 43% (3/7) of the 15-min group (P = 0.04). One-hour post-ROSC survival was 75%, 50%, and 14% in 5-, 10-, and 15-min groups, respectively (P = 0.02). One-hour survivors in the 5-min group required less norepinephrine (1.31 mg ±â€Š0.83 mg) compared with 10-SAAP (0.76 mg ±â€Š0.24 mg), P = 0.008. CONCLUSION: Whole blood SAAP can accomplish ROSC at high rates even after 10 min of unsupported cardiac arrest secondary to hemorrhage, with some viability beyond to 15 min. This is promising as a tool for ECA, but requires additional optimization and clinical trials.Animal Use Protocol, IACUC: 0919015.

Resuscitative endovascular balloon occlusion of the aorta associated with improved survival in hemorrhagic shock.

BACKGROUND: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is controversial as a hemorrhage control adjunct due to lack of data with a suitable control group. We aimed to determine outcomes of trauma patients in shock undergoing REBOA versus no-REBOA. METHODS: This single-center, retrospective, matched cohort study analyzed patients ≥16 years in hemorrhagic shock without cardiac arrest (2000-2019). REBOA (R; 2015-2019) patients were propensity matched 2:1 to historic (H; 2000-2012) and contemporary (C; 2013-2019) groups. In-hospital mortality and 30-day survival were analyzed using chi-squared and log rank testing, respectively. RESULTS: A total of 102,481 patients were included (R = 57, C = 88,545, H = 13,879). Propensity scores were assigned using age, race, mechanism, lowest systolic blood pressure, lowest Glasgow Coma Score (GCS), and body region Abbreviated Injury Scale scores to generate matched groups (R = 57, C = 114, H = 114). In-hospital mortality was significantly lower in the REBOA group (19.3%) compared to the contemporary (35.1%; p = 0.024) and historic (44.7%; p = 0.001) groups. 30-day survival was significantly higher in the REBOA versus no-REBOA groups. CONCLUSION: In a high-volume center where its use is part of a coordinated hemorrhage control strategy, REBOA is associated with improved survival in patients with noncompressible torso hemorrhage.

Class of hemorrhagic shock is associated with progressive diastolic coronary flow reversal and diminished left ventricular function.

Introduction: The relationship between coronary artery flow and left ventricular (LV) function during hemorrhagic shock remains unknown. The aim of this study was to quantify coronary artery flow directionality alongside left ventricular function through the four classes of hemorrhage shock. Methods: Following baseline data collection, swine were exsanguinated into cardiac arrest via the femoral artery using a logarithmic bleed, taking each animal through the four classes of hemorrhagic shock based on percent bleed (class I: 15%; class II: 15%-30%; class III: 30%-40%; class IV: >40%). Telemetry data, left ventricular pressure-volume loops, and left anterior descending artery flow tracings over numerous cardiac cycles were collected and analyzed for each animal throughout. Results: Five male swine (mean 72 ± 12 kg) were successfully exsanguinated into cardiac arrest. Mean left ventricular end-diastolic volume, end-diastolic pressure, and stroke work decreased as the hemorrhagic shock class progressed (p < 0.001). The proportion of diastole spent with retrograde coronary flow was also associated with class of hemorrhagic shock (mean 5.6% of diastole in baseline, to 63.9% of diastole in class IV; p < 0.0001), worsening at each class from baseline through class IV. Preload recruitable stroke work (PRSW) decreased significantly in classes II through IV (p < 0.001). Systemic Vascular Resistance (SVR) is associated with class of hemorrhage shock (p < 0.001). Conclusion: With progressive classes of hemorrhagic shock left ventricular function progressively decreased, and the coronary arteries spent a greater proportion of diastole in retrograde flow, with progressively more negative total coronary flow. Preload recruitable stroke work, a load-independent measure of inotropy, also worsened in severe hemorrhagic shock, indicating the mechanism extends beyond the drop in preload and afterload alone.

The functional vascular anatomy of the swine for research.

OBJECTIVES: Swine (Sus Scrofa) are utilized broadly in research settings, given similarities to human vessel size and function; however, there are some important differences for clinicians to understand in order to interpret and perform translational research. This review article uses angiograms acquired in the course of a translational research program to present a description of the functional anatomy of the swine. METHODS: Digital subtraction angiography and computed tomography angiography were obtained throughout the course of multiple studies utilizing power injection with iodinated contrast. Subtracted two-dimensional images and three-dimensional multiplanar reformations were utilized post image acquisition to create maximal intensity projections and three-dimensional renderings of using open-source software (OsiriX). These imaging data are presented along with vessel measurements for reference. RESULTS: An atlas highlighting swine vascular anatomy, with an emphasis on inter-species differences that may influence how studies are conducted and interpreted, was compiled. CONCLUSIONS: Swine are utilized in broad-reaching fields for preclinical research. While many similarities between human and swine vasculature exist, there are important differences to consider when conducting and interpreting research. This review article highlights these differences and presents accompanying images to inform clinicians gaining experience in swine research.

A feasibility study of partial REBOA data in a high-volume trauma center.

PURPOSE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to temporize patients with infradiaphragmatic hemorrhage. Current guidelines advise < 30 min, to avoid ischemia/ reperfusion injury, whenever possible. The technique of partial REBOA (P-REBOA) has been developed to minimize the effects of distal ischemia. This study presents our clinical experience with P-REBOA, comparing outcomes to complete occlusion (C-REBOA). PATIENTS AND METHODS: Retrospective analysis of patients' electronic data and local REBOA registry between January 2016 and May 2019. INCLUSION CRITERIA: adult trauma patients who received Zone I C-REBOA or P-REBOA for infradiaphragmatic hemorrhage, who underwent attempted exploration in the operating room. Comparison of outcomes based on REBOA technique (P-REBOA vs C-REBOA) and occlusion time (> 30 min, vs ≤ 30 min) RESULTS: 46 patients were included, with 14 treated with P-REBOA. There were no demographic differences between P-REBOA and C-REBOA. Prolonged (> 30 min) REBOA (regardless of type of occlusion) was associated with increased mortality (32% vs 0%, p = 0.044) and organ failure. When comparing prolonged P-REBOA with C-REBOA, there was a trend toward lower ventilator days [19 (11) vs 6 (9); p = 0.483] and dialysis (36.4% vs 16.7%; p = 0.228) with significantly less vasopressor requirement (72.7% vs 33.3%; p = 0.026). CONCLUSION: P-REBOA can be delivered in a clinical setting, but is not currently associated with improved survival in prolonged occlusion. In survivors, there is a trend toward lower organ support needs, suggesting that the technique might help to mitigate ischemic organ injury. More clinical data are needed to clarify the benefit of partial occlusion REBOA.

Integrating Endovascular and Operative Intervention in Trauma.

BACKGROUND: Patterns of utilization of the hybrid operating room (hybrid-OR) in trauma have not been described. The aim of this study was to describe the sequencing and integration of endovascular and operative interventions in trauma using a hybrid-OR. MATERIALS AND METHODS: This is a single-center, retrospective cohort study of trauma patients who underwent both endovascular and operative intervention (2013-2019). Patients were separated into four groups based on procedure patterns: concomitant-linked (C-L), concomitant-independent, serial-linked (S-L) and serial-independent (S-I). The groups were defined as follows: C-L - related endovascular and operative interventions in the same OR; concomitant-independent - unrelated interventions in the same OR; S-L - related interventions in separate ORs; S-I - unrelated interventions in separate ORs. Patient characteristics, procedures performed and time to angiography in each group were analyzed. RESULTS: Out of 202 patients, most procedures utilizing the hybrid-OR were for hemorrhage control (84.1%) and were performed in a C-L manner (36.1%). Patients in the C-L group were most likely to undergo lower extremity revascularization and received the most transfusions. Patients in the S-L and S-I groups were more severely injured, had greater severe abdominal injury and were more likely to undergo damage control surgery and solid organ interventions, respectively. The C-L group had the highest percentage of patients to undergo angiography within 12 h (77%, P = 0.053). CONCLUSION: The hybrid-OR is an ideal space for hemorrhage control in trauma, but there is room for improvement in the triage of patients with non-compressible torso hemorrhage. Current practice patterns prioritize the hybrid-OR for management of lower extremity injury and are not optimal. Use of the hybrid-OR could be improved by concomitant management of patients with severe abdominal injury requiring damage control surgery.

Certification in endovascular hemostasis for trauma surgeons: Possible and practical?

BACKGROUND: Endovascular hemostasis is commonplace with many practitioners providing services. Accruing sufficient experience during training could allow acute care surgeons (ACSs) to expand their practice. We quantified case load and training opportunities at our center, where dedicated dual-trained ACS/vascular surgery faculty perform these cases. Our aim was to assess whether ACS fellows could obtain sufficient experience in 6 months of their fellowship in order to certify in these techniques, per the requirements of other specialties. METHODS: We performed a retrospective case series where we reviewed 6 years (2013-2018) of endovascular activity at an academic, level I trauma center quantifying arterial access, angiography, embolization, stent and stent graft placement, and IVC filter procedures. This was compared with the certification requirements for interventional radiology, vascular surgery, cardiothoracic surgery, and interventional cardiology. RESULTS: Between 2013 and 2018, 1,179 patients with a mean ± SD Injury Severity Score of 22.47 ± 13.24, underwent 4960 procedures. Annual rates per procedure, expressed as median (interquartile range), were arterial access 193.5 (181-195.5), diagnostic angiography 352 (321.5-364.5), embolization 90.5 (89.25-93.25), stent placement 24 (13.5-29.25), and IVC filter procedures 16.5 (10-23.75). Our 6-month case volume exceeded or was within 85% of the required number of cases for vascular surgery and interventional radiology training, with the exception of stent-graft deployment for both specialties, and therapeutic procedures for vascular surgery. CONCLUSION: The case volume at a large trauma center with a dedicated endovascular trauma service is sufficient to satisfy the case requirements for endovascular certification. Our trainees are already acquiring this experience informally. An endovascular trauma curriculum should now be developed to support certification within ACS fellowship training.

Targeted Regional Optimization: Increasing the Therapeutic Window for Endovascular Aortic Occlusion In Traumatic Hemorrhage.

ABSTRACT: Resuscitative endovascular balloon occlusion of the aorta (REBOA) allows for effective temporization of exsanguination from non-compressible hemorrhage (NCTH) below the diaphragm. However, the therapeutic window for aortic occlusion is time-limited given the ischemia-reperfusion injury generated. Significant effort has been put into translational research to develop new strategies to alleviate the ischemia-reperfusion injury and extend the application of endoaortic occlusion. Targeted regional optimization (TRO) is a partial REBOA strategy to augment proximal aortic and cerebral blood flow while targeting minimal threshold of distal perfusion beyond the zone of partial aortic occlusion. The objective of TRO is to reduce the degree of ischemia caused by complete aortic occlusion while providing control of distal hemorrhage. This review provides a synopsis of the concept of TRO, pre-clinical, translational experiences with TRO and early clinical outcomes. Early results from TRO strategies are promising; however, further studies are needed prior to large-scale implementation into clinical practice.

Measuring Cardiac Output in a Swine Model.

Swine are frequently used in medical research given their similar cardiac physiology to that of humans. Measuring cardiac parameters such as stroke volume and cardiac output are essential in this type of research. Contrast ventriculography, thermodilution, and pressure-volume loop (PV-loop) catheters can be used to accurately obtain cardiac performance data depending on which resources and expertise are available. For this study,five Yorkshire swine were anesthetized and intubated. Central venous and arterial access was obtained to place the necessary measurement instruments.A temperature probe was placed in the aortic root. A cold saline bolus was delivered to the right atrium and temperature deflection curve was recorded. Integration of the area under the curve allowed for the calculation of the current cardiac output.A pigtail catheter was percutaneously placed in the left ventricle and 30 mL of iodinated contrast was power injected over 2 seconds. Digital subtraction angiography images were uploaded to volumetric analysis software to calculate the stroke volume and cardiac output. A pressure volume-loop catheter was placed into the left ventricle (LV) and provided continuous pressure and volume data of the LV, which allowed the calculation of both stroke volume and cardiac output.All three methods demonstrated good correlation with each other. The PV-loop catheter and thermodilution exhibited the best correlation with a 3% error and a Pearson coefficient of 0.99, with 95% CI=0.97 to 1.1, (p=0.002). The PV-loop catheter against ventriculography also showed good correlation with a 6% error and a Pearson coefficient of 0.95, 95% CI=0.96 to 1.1 (p=0.01). Finally, thermodilution against ventriculography had a 2% error with r=0.95, 95% CI=0.93 to 1.11, (p=0.01). In conclusion, we state that the PV-loop catheter, contrast ventriculography, and thermodilution each offer certain advantages depending on the researcher's requirements. Each method is reliable and accurate for measuring various cardiac parameters in swine such as the stroke volume and cardiac output.

Selective aortic arch perfusion versus open cardiac massage in exsanguination cardiac arrest: A comparison of coronary pressure dynamics in swine.

AIM: To evaluate the mean aortic-right atrial pressure (AoP-RAP) gradients and mean coronary perfusion pressures (CPPs) observed during open cardiac massage (OCM) versus those obtained with selective aortic arch perfusion (SAAP) in post-mortem hypovolemic swine. METHODS: Post-mortum, male swine, utilized in prior studies of hemorrhage, were included in the study. Animals were bled ∼25-50% of circulating volume prior to death. Animals either underwent clamshell thoracotomy and OCM immediately after death was confirmed (n = 6) or underwent SAAP within 5-15 min of death (n = 6). Aortic root and right atrial pressures were recorded continuously during each method of resuscitation using solid state blood pressure catheters. Representative five beat samples were extracted; short, similarly timed segments of SAAP were also extracted. Mean AoP-RAP gradient and CPPs were calculated and compared. RESULTS: Mean AoP-RAP gradient and CPP were significantly higher in SAAP animals compared to OCM animals (mean ±â€¯SD; 29.1 ±â€¯8.4 vs. 24.5 ±â€¯5.0, p < 0.001; 28.9 ±â€¯8.5 vs. 9.9 ±â€¯6.0, p < 0.001). Mean CPP was not significantly different from mean AoP-RAP gradient in SAAP animals (p = 0.92); mean CPP was significantly lower than mean AoP-RAP gradient in OCM animals (p < 0.001). While 97% of SAAP segments had a CPP > 15 mmHg, only 17% of OCM segments had a CPP > 15 mmHg (p < 0.001). CONCLUSION: SAAP appears to create a more favorable and efficient hemodynamic profile for obtaining ROSC when compared to OCM in this preclinical porcine study.

Outcomes following abdominal trauma in Scotland.

PURPOSE: Traumatic abdominal injury is associated with significant mortality, especially in hemodynamically unstable patients. Trauma management now supports more conservative surgical management with judicious non-operative management. The aim of this study is to use STAG data to characterize abdominal trauma outcomes, focusing on factors that may influence mortality. METHODS: A retrospective analysis of prospectively collected STAG data was queried using AIS codes for Scottish abdominal trauma patients between 2011 and 2015. Patients were divided into non-survivor and survivor groups, reflecting mortality. Following this, outcomes and injury patterns of patients undergoing operative or non-operative management were compared between groups. RESULTS: A total of 1226 were analyzed. The mean age of the cohort was 42.47 ± 19.42 years, with most patients suffering blunt injuries. Non-survivors had more severe injuries to the liver, diaphragm, pancreas, vasculature, and pelvis (p < 0.001, p = 0.005, p = 0.025, p < 0.001, and p < 0.001, respectively). Survivors more often received CT scanning (0.09 [0.03-0.27]) and underwent surgical intervention (57.4% vs 39.7%; p = 0.001). Non-survivors more often had a shorter time till operative intervention (2.6 h vs 6.3 h, p < 0.001). CONCLUSIONS: About 7% of patients in the STAG registry display abdominal injury. Mortality was found to have strong associations with older age, hemodynamic instability, poor neurological status, and head and neck injury. Outcomes may improve with the anticipated creation of the Scottish Trauma System.

State-of-the-Art Review-Endovascular Resuscitation.

ABSTRACT: The emerging concept of endovascular resuscitation applies catheter-based techniques in the management of patients in shock to manipulate physiology, optimize hemodynamics, and bridge to definitive care. These interventions hope to address an unmet need in the care of severely injured patients, or those with refractory non-traumatic cardiac arrest, who were previously deemed non-survivable. These evolving techniques include Resuscitative Endovascular Balloon Occlusion of Aorta, Selective Aortic Arch Perfusion, and Extracorporeal Membrane Oxygenation and there is a growing literature base behind them. This review presents the up-to-date techniques and interventions, along with their application, evidence base, and controversy within the new era of endovascular resuscitation.

Mesenteric vascular disease: A population-based cohort study.

OBJECTIVES: Mesenteric vascular disease carries a high risk of mortality and morbidity; however, due to obscure clinical presentation, it can be under-recognized. Currently, epidemiology of mesenteric vascular disease remains poorly defined. The aim of this study is to analyze changes in Scottish mortality rates from mesenteric vascular disease overtime. METHODS: This is a retrospective, longitudinal population-based cohort study using data extracted from death certificates and Scottish Index of Multiple Deprivation. All deaths related to a vascular disorder of the intestines recorded as an underlying cause of death between 1979 and 2014 were identified using International Classification of Disease-9 or International Classification of Disease-10 code groups. Data included demographics and location of death. The residence postcodes were used to classify socio-economic status using the Scottish Index of Multiple Deprivation. RESULTS: From 2,142,921 deaths over 36 years, 14,530 (0.7%) were due to mesenteric vascular disease with a median (interquartile range) age of 77 and a 2:1 female to male gender ratio. The mean ± standard deviation age significantly increased from 72.6 ± 12.1 in 1979 to 76.8 ± 11.1 in 2014 (p < 0.001, R2 = 0.772). Males were consistently younger than females at the time of death. The two lowest Scottish Index of Multiple Deprivation categories accounted for half of the cohort, throughout the study period (p = 0.068). The adjusted death rate per 100,000 population increased from 7.6 in 1979 to 12.1 in 2014. CONCLUSIONS: The reported death rates of mesenteric vascular disease in Scotland between 1979 and 2014 have nearly doubled. Mesenteric vascular disease affects twice as many women as men and is associated with social deprivation. The increased reporting of mesenteric vascular disease is likely due to increased recognition and incidence. These implications should be considered when planning healthcare provision in Scotland.

The Cardiac Physiology Underpinning Exsanguination Cardiac Arrest: Targets for Endovascular Resuscitation.

ABSTRACT: Exsanguination leading to cardiac arrest is the terminal phase of uncontrolled hemorrhage. Resuscitative interventions have focused on preload and afterload support. Outcomes remain poor due to several factors but poor coronary perfusion undoubtedly plays a role. The aim of this study is to characterize the relationship between arterial pressure and flow during hemorrhage in an effort to better describe the terminal phases of exsanguination.Male swine weighing 60 kg to 80 kg underwent splenectomy and instrumentation followed by a logarithmic exsanguination until asystole. Changes in hemodynamic parameters over time were compared using one-way, repeated measures analysis of variance.Nine animals weighing 69 ±â€Š15 kg were studied. Asystole occurred at 53 ±â€Š13 min when 52 ±â€Š11% of total blood volume has been shed. The greatest fall in mean hemodynamic indices were noted in the first 15 min: SBP (80-42 mm Hg, P = 0.02), left ventricular end-diastolic volume (94-52 mL, P = 0.04), cardiac output (4.8-2.4 L/min, P = 0.03), coronary perfusion pressure (57-30 mm Hg, P = 0.01), and stroke volume (60-25 mL, P = 0.02). This corresponds to the greatest rate of exsanguination. Organized cardiac activity was observed until asystole without arrythmias. Coronary flow was relatively preserved throughout the study, with a precipitous decline once mean arterial pressure was less than 20 mm Hg, leading to asystole.In this model, initial hemodynamic instability was due to preload failure, with asystole occurring relatively late, secondary to failure of coronary perfusion. Future resuscitative therapies need to directly address coronary perfusion failure if effective attempts are to be made to salvage these patients.

Development of a Selective Aortic Arch Perfusion System in a Porcine Model of Exsanguination Cardiac Arrest.

Hemorrhage constitutes the majority of potentially preventable deaths from trauma. There is growing interest in endovascular resuscitation techniques such as selective aortic arch perfusion (SAAP) for patients in cardiac arrest. This involves active perfusion of the coronary circulation via a thoracic aortic balloon catheter and is approaching clinical application. However, the technique is complex and requires refinement in animal models before human use can be considered. This paper describes a large animal model of exsanguination cardiac arrest treated with a bespoke SAAP system. Swine were anesthetized, instrumented and a splenectomy was performed before a controlled, logarithmic exsanguination was initiated. Animals were heparinized and the shed blood collected in a reservoir. Once cardiac arrest was observed, the blood was pumped through an extra-corporeal circuit into an oxygenator and then delivered through a 10 Fr balloon catheter placed in the thoracic aorta. This resulted in the return of a spontaneous circulation (ROSC) as demonstrated by ECG and aortic root pressure waveform. This model and accompanying SAAP system allow for standardized and reproducible recovery from exsanguination cardiac arrest.