Treatment approach for coexisting chest wall fractures and unstable thoracolumbar spine fractures in polytrauma patients requiring prone spine surgery.

Concomitant chest wall fractures (sternal and/or rib fractures) with unstable thoracolumbar fractures that require surgical fixation are rare but highly morbid injuries that mandate a multidisciplinary approach to treatment. There is limited evidence in the literature regarding optimal timing and order of surgical fixation of these patients with multiple injuries. Here, we present our experience with two patients at a single institution that demonstrates the challenges that present with this patient population. We advocate for earlier fixation of the chest wall fractures in the appropriately indicated patients, prior to prone positioning for spinal fixation.

Percutaneous thoracostomy with thoracic lavage for traumatic hemothorax: a performance improvement initiative.

Objectives: Percutaneously placed small-bore (14 Fr) catheters and pleural lavage have emerged independently as innovative approaches to hemothorax management. This report describes techniques for combining percutaneous thoracostomy with pleural lavage and presents results from a performance improvement series of patients managed with percutaneous thoracostomy with immediate lavage. Methods: This was a prospective performance improvement series of patients treated at a level 1 trauma center with percutaneous thoracostomy and immediate lavage between April 2021 and May 2023. Results: Percutaneous thoracostomy with immediate lavage was used to treat nine hemodynamically normal patients with acute hemothorax. Injuries included both blunt and penetrating mechanisms. 56% of patients presented immediately after injury, and 44% presented in a delayed fashion ranging from 2 to 26 days after injury. Median length of stay was 6 days (IQR 6, 9). Seven patients were discharged home in stable condition, one was discharged to an acute rehabilitation facility, and one was discharged to a skilled nursing facility. Conclusions: Percutaneous thoracostomy with pleural lavage is clinically feasible and effective and warrants further evaluation with a multicenter clinical trial. Level of evidence: Therapeutic/care management, level V.

Thoracic Lavage for Traumatic Hemothorax.

This Surgical Innovation discusses thoracic lavage for traumatic hemothorax.

CT-based pleural effusion volume estimation formula demonstrates low accuracy and reproducibility for traumatic hemothorax.

PURPOSE: We aimed to evaluate the accuracy and reproducibility of the CT-based volume estimation formula V = d2 * h, where d and h represent the maximum depth and height of the effusion, for acute traumatic hemothorax. MATERIALS & METHODS: Prospectively identified patients with CT showing acute traumatic hemothorax were considered. Volumes were retrospectively estimated using d2 * h, then manually measured on axial images. Subgroup analysis was performed on borderline-sized hemothorax (200-400 mL). Measurements were repeated by three non-radiologists. Bland-Altman analysis was used to assess agreement between the two methods and agreement between raters for each method. RESULTS: A total of 46 patients (median age 34; 36 men) with hemothorax volume 23-1622 mL (median 191 mL, IQR 99-324 mL) were evaluated. Limits of agreement between estimates and measured volumes were -718 - +842 mL (± 202 mL). Borderline-sized hemothorax (n = 13) limits of agreement were -300 - +121 mL (± 114 mL). Of all hemothorax, 85 % (n = 39/46) were correctly stratified as over or under 300 mL, and of borderline-sized hemothorax, 54 % (n = 7/13). Inter-rater limits of agreement were -251 - +350, -694 - +1019, and -696 - +957 for the estimation formula, respectively, and -124 - +190, -97 - +111, and -96 - +46 for the measured volume. DISCUSSION: An estimation formula varies with actual hemothorax volume by hundreds of mL. There is low accuracy in stratifying hemothorax volumes close to 300 mL. Variability between raters was substantially higher with the estimation formula than with manual measurements.

Predictors of initial management failure in traumatic hemothorax: A prospective multicenter cohort analysis.

BACKGROUND: Traumatic hemothorax is common, and management failure leads to worse outcomes. We sought to determine predictive factors and understand the role of trauma center performance in hemothorax management failure. METHODS: We prospectively examined initial hemothorax management (observation, pleural drainage, surgery) and failure requiring secondary intervention in 17 trauma centers. We defined hemothorax management failure requiring secondary intervention as thrombolytic administration, tube thoracostomy, image-guided drainage, or surgery after failure of the initial management strategy at the discretion of the treating trauma surgeon. Patient-level predictors of hemothorax management failure requiring secondary intervention were identified for 2 subgroups: initial observation and immediate pleural drainage. Trauma centers were divided into quartiles by hemothorax management failure requiring secondary intervention rate and hierarchical logistic regression quantified variation. RESULTS: Of 995 hemothoraces in 967 patients, 186 (19%) developed hemothorax management failure requiring secondary intervention. The frequency of hemothorax management failure requiring secondary intervention increased from observation to pleural drainage to surgical intervention (12%, 22%, and 35%, respectively). The number of ribs fractured (odds ratio 1.12 per fracture; 95% confidence interval 1.00-1.26) and pulmonary contusion (odds ratio 2.25, 95% confidence interval 1.03-4.91) predicted hemothorax management failure requiring secondary intervention in the observation subgroup, whereas chest injury severity (odds ratio 1.58; 95% confidence interval 1.17-2.12) and initial hemothorax volume evacuated (odds ratio 1.10 per 100 mL; 95% confidence interval 1.05-1.16) predicted hemothorax management failure requiring secondary intervention after pleural drainage. After adjusting for patient characteristics in the logistic regression model for hemothorax management failure requiring secondary intervention, patients treated at high hemothorax management failure requiring secondary intervention trauma centers were 6 times more likely to undergo an intervention after initial hemothorax management failure than patients treated in low hemothorax management failure requiring secondary intervention trauma centers (odds ratio 6.18, 95% confidence interval 3.41-11.21). CONCLUSION: Failure of initial management of traumatic hemothorax is common and highly variable across trauma centers. Assessing patient selection for a given management strategy and center-level practices represent opportunities to improve outcomes from traumatic hemothorax.

Effects of prior injury on long term patient reported outcomes after trauma.

BACKGROUND: Trauma is an episodic, chronic disease with substantial, long-term physical, psychological, emotional, and social impacts. However, the effect of recurrent trauma on these long-term outcomes remains unknown. We hypothesized that trauma patients with a history of prior traumatic injury (PTI) would have poorer outcomes 6 months (6mo) after injury compared with patients without PTI. METHODS: Adult trauma patients admitted at an urban, academic, Level I trauma center were screened for inclusion (October 2020 to November 2021). Enrolled patients were administered the PROMIS-29 instrument, the primary care post-traumatic stress disorder screen, and standardized questions about prior trauma hospitalization, substance use, employment, and living situation at baseline and 6mo after injury. Assessment data was merged with clinical registry data, and outcomes were compared with respect to PTI. RESULTS: Of 3,794 eligible patients, 456 completed baseline assessments and 92 completed 6mo surveys. Between those with or without PTI, there were no differences at 6mo after injury in the proportion of patients reporting poor function in social participation, anxiety, depression, fatigue, pain interference, or sleep disturbance. Prior traumatic injury patients reported poor physical function less often than patients without PTI (10 [27.0%] vs. 33 [60.0%], p = 0.002). After controlling for age, gender, race, injury mechanism, and Injury Severity Score, PTI correlated with a fourfold decrease in poor physical function risk (adjusted odds ratio, 0.243; 95% confidence interval, 0.081-0.733; p = 0.012) in the multivariable logistic regression model. CONCLUSION: Compared with patients suffering their first injury, trauma patients with PTI have better self-reported physical function after a subsequent injury and otherwise equivalent outcomes across a range of HRQoL domains at 6mo. There remains substantial room for improvement to mitigate the long-term challenges faced by trauma patients and to facilitate their societal reintegration, regardless of the number of times they are injured. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level III.

Open versus percutaneous tube thoracostomy with and without thoracic lavage for traumatic hemothorax: a novel randomized controlled simulation trial.

Objective: To quantify and assess the relative performance parameters of thoracic lavage and percutaneous thoracostomy (PT) using a novel, basic science 2×2 randomized controlled simulation trial. Summary background data: Treatment of traumatic hemothorax (HTX) with open tube thoracostomy (TT) is painful and retained HTX is common. PT is potentially less painful whereas thoracic lavage may reduce retained HTX. Yet, procedural time and the feasibility of combining PT with lavage remain undefined. Methods: A simulated partially clotted HTX (2%-gelatin-saline mixture) was loaded into a TT trainer and then evacuated after randomization to one of four protocols: TT+/-lavage or PT+/-lavage. Standardized inserts with fixed 28-Fr TT or 14-Fr PT positioning were used to minimize tube positioning variability. Lavage consisted of two 500 mL aliquots of warm saline after initial HTX evacuation. The primary outcome was HTX volume evacuated. The secondary outcome was additional procedural time required for the addition of the lavage. Results: A total of 40 simulated HTX trials were randomized. TT alone evacuated a median of 1236 mL (IQR 1168, 1294) leaving a residual volume of 265 mL (IQR 206, 333). PT alone resulted in a significantly greater median residual volume of 588 mL (IQR 497, 646) (p=0.002). Adding lavage resulted in similar residual volumes for TT compared with TT alone but significantly less for PT compared with PT alone (p=0.002). Lavage increased procedural time for TT by a median of 7.0 min (IQR 6.5, 8.0) vs 11.7 min (IQR 10.2, 12.0) for PT (p<0.001). Conclusion: This simulation trial characterized HTX evacuation in a standardized fashion. Adding lavage to thoracostomy placement may improve evacuation, particularly for small-diameter tubes, with little added procedural time. Further prospective clinical study is warranted. Level of evidence: NA.

The hidden mortality of pediatric firearm violence.

INTRODUCTION: Firearms and motor vehicle collisions (MVC) are leading causes of mortality in children. We hypothesized that firearm injuries would have a higher mortality than MVCs in children and a higher level of resource utilization METHODS: Trauma patients <18 years old at a Level 1 pediatric trauma center sustaining gunshot wounds (GSW) or MVCs 2009-2019 were included. The primary outcome was mortality. The secondary outcome was immediate surgery. The California Department of Public Health's Overall Injury Surveillance tool was queried for patients <18 with GSW or MVC 2006-2015 to compare statewide case fatality rates (CFRs), and analyze proportions of GSWs by intent: assault, self-inflicted, and unintentional. RESULTS: Of 13,840 pediatric trauma patients at our institution, 295 GSWs (2.1%) and 4467 MVCs (32.3%) were included. Mortality was higher for GSWs (7.5% vs. 0.8%, p<0.0001). GSW patients were more likely to require immediate surgery (34.4% vs. 11.2%, p<0.0001). On multivariable analysis, GSW patients were 7.8-times more likely to die than MVC patients (OR 7.83, 95% CI 3.68-16.66, p<0.0001), adjusted for age, sex, and injury severity. Statewide, there were 10,790 pediatric GSWs with 1586 deaths (CFR 14.7%) vs. 710 deaths in 261,363 children in MVCs (CFR 0.3%, p<0.0001). The GSW CFR rose (13.4% to 16.5%, p = 0.05) while the MVC CFR decreased (0.5% to 0.2%, p<0.0001) in 2015 vs. 2006. CONCLUSION: Firearm violence in pediatric patients is significantly more lethal than MVCs and is resource intensive. The case fatality rate for pediatric firearm violence is rising. Resources must be directed at preventing pediatric firearm injuries. LEVEL OF EVIDENCE: Prognosis study, Level II.

Child-rearing During Postgraduate Medical Training and Its Relation to Stress and Burnout: Results From a Single-institution Multispecialty Survey.

INTRODUCTION: Child-rearing is difficult for medical trainees, but much of the available evidence is limited to individual specialties or lacks an analysis of well-being. In light of this, we sought to examine current perspectives across a wide range of medical specialties, determine associations with stress and burnout, and identify potential supportive solutions. METHODS: After Institutional Review Board approval, a voluntary and anonymous survey was sent to all residents and fellows at a large academic medical center with a U.S. Air Force joint training agreement in 2019. Frequency tables were generated for survey responses, using χ2 test for analysis between groups. RESULTS: One hundred and eighty-four physician trainees completed the survey (21.6% response rate), of which 38.0% were parents. Overall, 90.8% of trainees want children but 68.5% plan to wait until after training to start or grow their families, mainly due to insufficient time or inadequate child care. Less than 2% cited lack of program support as the reason. Among trainee parents, 72.0% reported that child care was at least quite stressful. Child care contributes to burnout for 68.6% of trainee parents, and there was no difference between medical and surgical trainees or between military and nonmilitary trainees. Day care was the most common primary child care strategy, and 37.1% of trainee parents reported spending >25% of their household income on child care. Proposed helpful solutions include on-site day care and subsidies. CONCLUSIONS: Most medical trainees in this sample want children, yet many are delaying growing their families due to time and financial constraints. For trainee parents, child care causes stress and family and financial strain and contributes to burnout. Physicians in training, including military members training at civilian medical centers, could benefit from child care assistance in order to relieve stress, reduce burnout, and improve well-being. Furthermore, by expanding existing resources and implementing new creative solutions to the challenges of child-rearing among medical professionals, the U.S. military has an opportunity to improve members' well-being and be a model to civilian graduate medical education programs nationwide.

The Enduring Health Consequences of Combat Trauma: a Legacy of Chronic Disease.

BACKGROUND: A better understanding of the long-term health effects of combat injury is important for the management of veterans' health in the Department of Defense (DoD) and Veterans Affairs (VA) health care systems and may have implications for primary care management of civilian trauma patients. OBJECTIVE: To determine the impact of traumatic injury on the subsequent development of hypertension (HTN), diabetes mellitus (DM), and coronary artery disease (CAD) after adjustment for sociodemographic, health behavior, and mental health factors. DESIGN: Retrospective cohort study of current and former US military personnel with data obtained from both the DoD and VA health care systems. PARTICIPANTS: Combat injured (n = 8727) service members between 1 February 2002 and 14 June 2016 randomly selected from the DoD Trauma Registry matched 1:1 based on year of birth, sex, and branch of service to subjects that deployed to a combat zone but were not injured. MAIN MEASURES: Traumatic injury, stratified by severity, compared with no documented injury. Diagnoses of HTN, DM, and CAD defined by International Classification of Diseases 9th or 10th Revision Clinical Modification codes. KEY RESULTS: After adjustment, severe traumatic injury was significantly associated with HTN (HR 2.78, 95% CI 2.18-3.55), DM (HR 4.45, 95% CI 2.15-9.18), and CAD (HR 4.87, 95% CI 2.11-11.25), compared with no injury. Less severe injury was associated with HTN (HR 1.14, 95% CI 1.05-1.24) and CAD (HR 1.62, 95% CI 1.11-2.37). CONCLUSIONS: Severe traumatic injury is associated with the subsequent development of HTN, DM, and CAD. These findings have profound implications for the primary care of injured service members in both the DoD/VA health systems and may be applicable to civilian trauma patients as well. Further exploration of pathophysiologic, health behavior, and mental health changes after trauma is warranted to guide future intervention strategies.

Persistent Opioid Use After Combat Injury and Subsequent Long-term Risk of Abuse: A Retrospective Cohort Study.

OBJECTIVE: To determine whether persistent opioid use after injury is associated with subsequent long-term development of clinically recognized opioid abuse. SUMMARY BACKGROUND DATA: Opioid abuse is an epidemic in the United States and trauma can initiate persistent use; however, it remains unclear whether persistent opioid use contributes to the subsequent development of opioid abuse. The care of combat casualties by the Departments of Defense and Veterans Affairs uniquely allows investigation of this long-term outcome. METHODS: This retrospective cohort study randomly selected 10,000 battle-injured United States military personnel. We excluded patients who died during initial hospitalization or within 180 days of discharge, had a preinjury opioid abuse diagnosis, or had missing data in a preselected variable. We defined persistent opioid use as filling an opioid prescription 3 to 6 months after discharge and recorded clinically recognized opioid abuse using relevant diagnosis codes. RESULTS: After exclusion, 9284 subjects were analyzed, 2167 (23.3%) of whom developed persistent opioid use. During a median follow-up time of 8 years, 631 (6.8%) patients developed clinically recognized opioid abuse with a median time to diagnosis of 3 years. Injury severity and discharge opioid prescription amount were associated with persistent opioid use after trauma. After adjusting for patient and injury-specific factors, persistent opioid use was associated with the long-term development of clinically recognized opioid abuse (adjusted hazard ratio, 2.39; 95% confidence interval, 1.99-2.86). CONCLUSIONS: Nearly a quarter of patients filled an opioid prescription 3 to 6 months after discharge, and this persistent use was associated with long-term development of opioid abuse.

High Versus Low Volume Fluid Resuscitation Strategies in a Porcine Model (Sus scrofa) of Combined Thermal and Traumatic Brain Injury.

BACKGROUND: Combined burn and traumatic brain injury (TBI) treatment priorities may not align due to opposing fluid resuscitation paradigms used in treating burns and TBI. We developed a porcine model of combined thermal injury/TBI and compared an "aggressive" fluid resuscitation strategy using the Parkland formula and a "restrictive" resuscitation strategy using the modified Brooke formula. METHODS: Twenty-eight swine were deeply anesthetized and received a 40% total body surface area full-thickness burn injury and TBI. Swine were then randomized to receive restrictive or aggressive resuscitation for 8 h after which time animals were euthanized and necropsy was performed. Volume of brain injury was assessed after analyzing segmental slices of brain tissue. RESULTS: There were no differences between the restrictive and aggressive resuscitation groups in blood pressure, heart rate, central venous pressure, intra-cranial pressure (ICP), or serum lactate levels after 8 h of resuscitation. Urine output was higher in the aggressive resuscitation group. The restrictive group had a significantly higher serum blood urea nitrogen (BUN) compared with baseline and compared with the aggressive group. There was no significant difference in size of brain injury between groups. CONCLUSIONS: Both restrictive and aggressive resuscitation demonstrated adequate resuscitation at 8 h postinjury. Increased serum BUN in the restrictive group may be an indicator of early acute kidney injury, despite adequate urine output. Resuscitation strategy did not appear to affect ICP or the size of brain injury.

Improvised Field Expedient Method for Renal Replacement Therapy in a Porcine Model of Acute Kidney Injury.

OBJECTIVE: Dialysis patients may not have access to conventional renal replacement therapy (RRT) following disasters. We hypothesized that improvised renal replacement therapy (ImpRRT) would be comparable to continuous renal replacement therapy (CRRT) in a porcine acute kidney injury model. METHODS: Following bilateral nephrectomies and 2 hours of caudal aortic occlusion, 12 pigs were randomized to 4 hours of ImpRRT or CRRT. In the ImpRRT group, blood was circulated through a dialysis filter using a rapid infuser to collect the ultrafiltrate. Improvised replacement fluid, made with stock solutions, was infused pre-pump. In the CRRT group, commercial replacement fluid was used. During RRT, animals received isotonic crystalloids and norepinephrine. RESULTS: There were no differences in serum creatinine, calcium, magnesium, or phosphorus concentrations. While there was a difference between groups in serum potassium concentration over time (P < 0.001), significance was lost in pairwise comparison at specific time points. Replacement fluids or ultrafiltrate flows did not differ between groups. There were no differences in lactate concentration, isotonic crystalloid requirement, or norepinephrine doses. No difference was found in electrolyte concentrations between the commercial and improvised replacement solutions. CONCLUSION: The ImpRRT system achieved similar performance to CRRT and may represent a potential option for temporary RRT following disasters.

Quantifying the need for pediatric REBOA: A gap analysis.

BACKGROUND: Trauma is the leading cause of death in children. Resuscitative endovascular balloon occlusion of the aorta (REBOA) provides temporary hemorrhage control, but its potential benefit has not been assessed in children. We hypothesized that there are pediatric patients who may benefit from REBOA. METHODS: Trauma patients <18 years old at a level 1 pediatric trauma center between 2009 and 2019 were queried for deaths, pre-hospital cardiac arrest, massive transfusion protocol activation, transfusion requirement, or hemorrhage control surgery. These patients defined the cohort of severely injured patients. From this cohort, patients with intraabdominal injuries for which REBOA may provide temporary hemorrhage control were identified, including solid organ injury necessitating intervention, vascular injury, or pelvic hemorrhage. RESULTS: There were 239 severely injured patients out of 6538 pediatric traumas. Of these, 38 had REBOA-amenable injuries (15.9%) with 34.2% mortality, accounting for 10.2% of all pediatric trauma deaths at one center. Eleven patients with REBOA-amenable injuries had TBI (28.9%). Patients with REBOA-amenable injuries represented 0.6% of all pediatric traumas. CONCLUSION: Nearly 20% of severely injured pediatric patients could potentially benefit from REBOA. The overall proportion of pediatric patients with REBOA-amenable injuries is similar to adult studies. TYPE OF STUDY: Retrospective comparative study. LEVEL OF EVIDENCE: Level III.

Does the pediatric hemodynamic cliff exist in response to hemorrhagic shock?

BACKGROUND: The paradigm that children maintain normal blood pressure during hemorrhagic shock until 30%-45% hemorrhage is widely accepted. There are minimal data supporting when decompensation occurs and how a child's vasculature compensates up to that point. We aimed to observe the arterial response to hemorrhage and when mean arterial pressure (MAP) decreased from baseline in pediatric swine. METHODS: Piglets were hemorrhaged in 20% increments of their total blood volume to 60%. MAP and angiograms of the thoracic aorta (TA) and abdominal arteries were obtained. Percent change in area of the vessels from baseline was calculated. RESULTS: Piglets (n = 8) had a differential vasoconstriction starting at 20% hemorrhage (celiac artery 36.3% [31.4-44.6] vs TA 16.7% [10.7-19.1] p = 0.0012). At 40% hemorrhage, the differential vasoconstriction favored shunting blood away from the abdominal visceral branches to the TA (celiac artery 54.7% [36.9-60.6] vs TA 29.5% [23.9-36.2] p = 0.0056 superior mesenteric artery 46.7% [43.9-68.6] vs TA 29.5% [23.9-36.2] p = 0.0100). This was exacerbated at 60% hemorrhage. MAP decreased from baseline at 20% hemorrhage (66.4 ±â€¯6.0 mmHg vs 41.4 ±â€¯10.4 mmHg, p < 0.0001), and worsened at 40% and 60% hemorrhage. CONCLUSION: In piglets, a differential vasocontriction shunting blood proximally occurred in response to hemorrhage. This did not maintain normal MAP at 20%, 40% or 60% hemorrhage. LEVEL OF EVIDENCE: Level II.

Automated Partial Versus Complete Resuscitative Endovascular Balloon Occlusion of the Aorta for the Management of Hemorrhagic Shock in a Pig Model of Polytrauma: a Randomized Controlled Pilot Study.

INTRODUCTION: Endovascular variable aortic control (EVAC) is an automated partial resuscitative endovascular balloon occlusion of the aorta (REBOA) platform designed to mitigate the deleterious effects of complete REBOA. Long-term experiments are needed to assess potential benefits. The feasibility of a 24-hour experiment in a complex large animal trauma model remains unknown. MATERIALS AND METHODS: Anesthetized swine were subjected to controlled hemorrhage, blunt thoracic trauma, and tibial fractures. Animals were then randomized (N = 3/group) to control (No balloon support), 90 minutes of complete supraceliac REBOA, or 10 minutes of supraceliac REBOA followed by 80 minutes of EVAC. One hundred ten minutes after injury, animals were resuscitated with shed blood, the REBOA catheter was removed. Automated critical care under general anesthesia was maintained for 24 hours. RESULTS: Animals in the control and EVAC groups survived to the end of the experiment. Animals in the REBOA group survived for 120, 130, and 660 minutes, respectively. Animals in the EVAC group displayed similar mean arterial pressure and plasma lactate concentration as the control group by the end of the experiment. Histologic analysis suggested myocardial injury in the REBOA group when compared with controls. CONCLUSIONS: This study demonstrates the feasibility of intermediate-term experiments in a complex swine model of polytrauma with 90 minutes of REBOA. EVAC may be associated with improved survival at 24 hours when compared with complete REBOA. EVAC resulted in normalized physiology after 24 hours, suggesting that prolonged partial occlusion is possible. Longer studies evaluating partial REBOA strategies are needed.

Esmolol reduces myocardial injury induced by resuscitative endovascular balloon occlusion of the aorta (REBOA) in a porcine model of hemorrhagic shock.

PURPOSE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) causes myocardial injury from increased aortic afterload and supraphysiologic cardiac output. However, pharmacologic methods to attenuate high cardiac output and reduce myocardial injury have not been explored. We hypothesized that the use of esmolol during REBOA would reduce myocardial injury. METHODS: Ten pigs were anesthetized and instrumented. Following 25% total blood volume hemorrhage, animals underwent 45 min of supraceliac (zone 1) REBOA with or without titration of esmolol to maintain heart rate between 80 and 100 beats per minute. Following the REBOA interventions, animals underwent 275 min of standardized critical care. RESULTS: During REBOA, heart rate was significantly lower in the esmolol group compared to control animals (100 [88 - 112] vs 193 [172 - 203] beats/minute, respectively, p < 0.001) and the average mean arterial pressure (MAP) was lower in the esmolol group (88.0 [80.3-94.9] vs 135.1 [131.7-140.4] mmHg, respectively, p = 0.01). During the critical care phase, there were no differences in heart rate or MAP between groups. Animals in the intervention group received 237.9 [218.7-266.5] µg/kg of esmolol. There was a significant increase from baseline in serum troponins for the control group (p = 0.006) and significantly more subendocardial hemorrhage compared to animals treated with esmolol (3 [3 - 3] and 0 [0 - 0], p = 0.009, respectively). CONCLUSION: In our porcine model of hemorrhagic shock, zone 1 REBOA was associated with myocardial injury. Pharmacologic heart rate titration with esmolol during occlusion may mitigate the deleterious effects of REBOA on the heart.

Reference Intervals for and the Effects of Sample Handling and Sex on Rotational Thromboelastometry in Healthy Adult Pigs.

Accurate assessment of coagulation in porcine studies is essential. We sought to establish normal values for porcine rotational thromboelastometry (ROTEM) according to the American Society for Veterinary Clinical Pathology guidelines and to assess the effects of various preanalytical parameters on those measurements. Healthy Yorkshire-cross pigs (n = 81; 46 males and 35 females) were anesthetized. By using a 18-gauge needle attached to a vacuum phlebotomy tube, blood was acquired from the cranial vena cava. Tubes were filled in the following order: evacuation clot tube, EDTA tube, heparin tube, and 2 citrate tubes. The citrate tubes were randomly assigned to 30 min with or without constant agitation on a rocker. The following parameters were reported according to the manufacturer's recommendations: clotting time, clot formation time, α, (tangent to the clot formation curve when the clot firmness is 20 mm), clot firmness after 10 and 20 min, maximal clot firmness, maximum lysis, and lysis indexes at 30 and 45 min. Reference intervals were reported as mean ± 2 SD (parametric distribution) or 2.5th and 97.5th percentile of the population's results (nonparametric distribution). The effects of sex, sampling order, and agitation on ROTEM results were analyzed through linear regression. Neither sex nor sample agitation influenced any of the ROTEM parameters. Combined reference intervals were established for each ROTEM parameter by pooling data from the nonagitated tubes for both male and female pigs. This study is the first to establish ROTEM reference intervals from a large number of male and female adult Yorkshire-cross pigs and to provide a detailed description of preanalytical sample processing.

Resuscitative endovascular balloon occlusion of the aorta in a pediatric swine model: Is 60 minutes too long?

BACKGROUND: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is recommended in adults with a noncompressible torso hemorrhage with occlusion times of less than 60 minutes. The tolerable duration in children is unknown. We used a pediatric swine controlled hemorrhage model to evaluate the physiologic effects of 30 minutes and 60 minutes of REBOA. METHODS: Pediatric swine weighing 20 kg to 30 kg underwent a splenectomy and a controlled 60% total blood volume hemorrhage over 30 minutes, followed by either zone 1 REBOA for 30 minutes (30R) or 60 minutes (60R). Swine were then resuscitated with shed blood and received critical care for 240 minutes. RESULTS: During critical care, the 30R group's (n = 3) pH, bicarbonate, base excess, and lactate were no different than baseline, while at the end of critical care, these variables continued to differ from baseline in the 60R group (n = 5) and were worsening (7.4 vs. 7.2, p < 0.001, 30.4 mmol/L vs. 18.4 mmol/L, p < 0.0001, 5.6 mmol/L vs. -8.5 mmol/L, p < 0.0001, 2.4 mmol/L vs. 5.7 mmol/L, p < 0.001, respectively). Compared with baseline, end creatinine and creatinine kinase were elevated in 60R swine (1.0 mg/dL vs. 1.7 mg/dL, p < 0.01 and 335.4 U/L vs. 961.0 U/L, p < 0.001, respectively), but not 30R swine (0.9 mg/dL vs. 1.2 mg/dL, p = 0.06 and 423.7 U/L vs. 769.5 U/L, p = 0.15, respectively). There was no difference in survival time between the 30R and 60R pediatric swine, p = 0.99. CONCLUSION: The physiologic effects of 30 minutes of zone 1 REBOA in pediatric swine mostly resolved during the subsequent 4 hours of critical care, whereas the effects of 60 minutes of REBOA persisted and worsened after 4 hours of critical care. Sixty minutes of zone 1 REBOA may create an irreversible physiologic insult in a pediatric population.

Effects of Extended Lower Extremity Cooling Following Zone 3 REBOA in a Porcine Hemorrhage Model.

INTRODUCTION: External cooling of ischemic limbs has been shown to have a significant protective benefit for durations up to 4 hours. MATERIALS AND METHODS: It was hypothesized that this benefit could be extended to 8 hours. Six swine were anesthetized and instrumented, then underwent a 25% total blood volume hemorrhage. Animals were randomized to hypothermia or normothermia followed by 8 hours of Zone 3 resuscitative endovascular balloon occlusion of the aorta, then resuscitation with shed blood, warming, and 3 hours of critical care. Physiologic parameters were continuously recorded, and laboratory specimens were obtained at regular intervals. RESULTS: There were no significant differences between groups at baseline. There were no significant differences between creatine kinase in the hypothermia group when compared to the normothermia group (median [IQR] = 15,206 U/mL [12,476-19,987] vs 23,027 U/mL [18,745-26,843]); P = 0.13) at the end of the study. Similarly, serum myoglobin was also not significantly different in the hypothermia group after 8 hours (7,345 ng/mL [5,082-10,732] vs 5,126 ng/mL [4,720-5,298]; P = 0.28). No histologic differences were observed in hind limb skeletal muscle. CONCLUSION: While external cooling during prolonged Zone 3 resuscitative endovascular balloon occlusion of the aorta appears to decrease ischemic muscle injury, this benefit appears to be time dependent. As the ischemic time approaches 8 hours, the benefit from hypothermia decreases.