Why do not we talk about MIS fellowship? A short review of the short literature.

BACKGROUND: The minimally invasive surgery (MIS) fellowship has existed for three decades and has steadily grown in both number of positions available and variety of techniques practiced. Despite continued popularity, growth, and wide breadth of surgical techniques of the MIS fellowship, publication rates in medical journals regarding these fellowships have not been as robust as one may expect. Our goal was to review the available literature on MIS fellowship. METHODS: We reviewed PubMed to search for articles pertinent for MIS fellowship. The initial search included "MIS fellowship" "minimally invasive surgery fellowship" and "laparoscopy fellowship." Articles pertaining to MIS fellowship were then reviewed by title and abstract for content. Articles were excluded from subsequent analysis if they focused on disciplines that were not direct extensions of general surgery (such as urology, gynecology, oncology). Using similar search techniques, we tabulated unfiltered publications rates specific to other major surgical fellowship disciplines. The metric articles per position was created by dividing the total number articles for each discipline by the annual fellowship positions RESULTS: An initial review of available literature produced 134 articles pertinent to MIS fellowship. Further analysis for direct relevance to MIS yielded only 58 published articles. MIS had the fewest number of publications and smallest APP, 0.7, of any of the major fellowship disciplines. CONCLUSIONS: There is a surprising dearth of material on MIS fellowship. While, MIS fellowship is a one-year experience, we have the opportunity to build on three decades of clinical experience to continue optimize the fellow experience and improve subspecialized surgical training and patient outcomes. This could be facilitated through broadened focus of inquiry and publication of findings.

Characterizing Brain Perfusion in a Swine Model of Raised Intracranial Pressure.

INTRODUCTION: Perfusion of the brain is critical, but this can be compromised due to focal space occupying lesions (SOL). SOLs can raise intracranial pressure (ICP), resulting in reduced cerebral blood flow (CBF). Most gyrencephalic models of brain injury focus on parenchymal injury, with few models of acutely elevated ICP. We hypothesized that we could employ a SOL technique to develop a titratable ICP model and sought to quantitate the resulting decrease in brain perfusion. METHODS: Six swine were anesthetized and instrumented. A Fogarty balloon catheter was inserted intracranially. Blood CO2 partial pressure was maintained between 35 and 45 mmHg. The Fogarty balloon was infused with normal saline at 1 mL/min to ICP targets of 10, 20, 30, and 40 mmHg. CBF (mL/100 g/min) were assessed at each ICP level using computed tomography perfusion (CTP). Data are presented as the mean ± standard deviation with all pressures measured in mmHg. CBF values were compared between baseline and each ICP level using analysis of variance. RESULTS: Baseline ICP was 5 ± 2 and systolic blood pressure was 106 ± 7. Balloon volumes (mL) required to achieve each incremental ICP level were 2.4 ± 0.5, 4.9 ± 1.7, 7.6 ± 1.6, and 9.9 ± 1.7. CBF decreased with each raised ICP level, with CBF being significantly less than baseline at ICP values of 30 (56.1 ± 34.7 versus 20.6 ± 11.0, P < 0.05) and 40 (56.1 ± 34.7 versus 6.5 ± 10.6, P < 0.05). CONCLUSIONS: An intracranial balloon catheter can be used to increase ICP, delivering a proportionate reduction in CBF. This model can be used in the future studies to examine adjuncts that manipulate intracranial pressure and their effect on brain perfusion.

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.

Development of an Endovascular Model of Pelvic Hemorrhage Using Volumetric Computed Tomography Validation.

PURPOSE: Uncontrolled pelvic hemorrhage from trauma is associated with mortality rates above 30%. The ability of an intervention to reduce blood loss from pelvic trauma is paramount to its success. The objective of this study was to determine if computed tomography volumetric analysis could be used to quantify blood loss in a porcine endovascular pelvic hemorrhage model. MATERIALS AND METHODS: Yorkshire swine under general anesthesia underwent balloon dilation and rupture of the profunda femoris artery, which was confirmed by digital subtraction angiography. Computed tomography angiography and postprocessing segmentation were performed to quantify pelvic hemorrhage volume at 5 and 30 minutes after injury. Continuous hemodynamic and iliofemoral flow data were obtained. Baseline and postinjury hemoglobin, hematocrit and lactate were collected. RESULTS: Of 6 animals enrolled, 5 survived the 30-minute post-injury period. One animal died at 15 minutes. Median volume of pelvic hemorrhage was 141±106 cm3 at 5 minutes and 302±79 cm3 at 30 minutes with a 114% median increase in hematoma volume over 25 minutes (p=0.040). There was a significant decrease in mean arterial pressure (107 to 71 mm Hg, p=0.030) and iliofemoral flow (561 to 122 mL/min, p=0.014) at 30 minutes postinjury, but no significant changes in hemoglobin, hematocrit, or heart rate. CONCLUSION: Computed tomography volumetric analysis can be used to quantify rate and volume of blood loss in a porcine endovascular pelvic hemorrhage model. Future studies can incorporate this approach when evaluating the effect of hemorrhage control interventions associated with pelvic fractures.

Use of Structured Presentation Formatting and NSQIP Guidelines Improves Quality of Surgical Morbidity and Mortality Conference.

BACKGROUND: Surgical Morbidity and Mortality (M&M) conference lacks a standardized structure across institutions. We compared implementation of structure and National Surgical Quality Improvement Program's (NSQIP) definitions to organize our M&M and identify cases for discussion versus the usually used method at many centers of case identification by an attending surgeon or resident. METHODS AND MATERIALS: A prospective study was performed, over a 10-wk period, to compare the identification of adverse events and the educational value of our M&M conference before and after implementation of structured NSQIP-defined presentations. Chart review was performed by a trained surgical clinical reviewer and trained NSQIP resident of all cases over the study period to identify NSQIP-defined occurrences. All presented M&Ms were evaluated for adequate reporting of adverse events and areas for improvement on a three-point scale. Surveys were administered before and after intervention to assess educational value to resident and faculty on a five-point Likert scale. Survey and presentation data were compared using Student's t-tests. P-values <0.05 were considered significant. RESULTS: Before intervention, 15% of NSQIP-defined occurrences were identified compared with 81% after intervention (P < 0.01). Thirty-three percent of deaths (1 of 3) before intervention were identified versus 100% (4 of 4) identified after intervention. Surveys obtained from faculty, residents, and students of individual presentations found improved clarity and educational content in cases presented (2.6-2.8) and improved identification of etiology (2.5-2.8), learning points (2.1-2.7), and opportunities for prevention of future adverse events (2.1-2.6) (all P < 0.01). Residents and faculty overall found that the postintervention model better identified adverse events (3.0-3.7, P = 0.02), opportunities for prevention (2.8-3.3, P = . 04), and promoted improved transparency (2.9-3.8, P < 0.01). Eighty-five percent of participants supported the changes in M&M conference. CONCLUSIONS: Incorporation of a clearly defined structure using NSQIP definitions for morbidity and identification of every mortality in our M&M conference standardized identification of adverse events thus improving conference quality. Consideration of the use of this structure should be given to other surgical departmental M&Ms.

Enrichment of tumor-initiating breast cancer cells within a mammosphere-culture microdevice.

We report for the first time a microdevice that enables the selective enrichment, culture, and identification of tumor-initiating cells on native polydimethylsiloxane (PDMS). For nearly a decade, researchers have identified tumor-initiating breast cancer cells within heterogeneous populations of breast cancer cells by utilizing low-attachment serum-free culture conditions, which lead to the formation of spheroidal colonies (mammospheres) that are enriched for tumor-initiating cells. However, the utility of this assay has been limited by difficulties in combining this culture-plate-based technique with other cellular and molecular analyses. Integrating the mammosphere technique into a microsystem can enable it to be combined directly with a number of functions, such as cell sorting, drug screens, and molecular assays. In this work, we demonstrate mammosphere culture within a PDMS microdevice. We first prove that a native hydrophobic PDMS surface is as effective as commercial low-attachment plates at selectively promoting the formation of mammospheres. We then experimentally assess the PDMS microdevice. Time-lapse images of mammosphere formation within the microdevice show that mammospheres form from single cells or small clusters of cells. Following formation of the mammospheres, it is desirable to evaluate the cells within the spheroids for enrichment of tumor initiating cells. To perform assays such as this (which require the loading and rinsing of reagents) without flushing the cells (which are in suspension) from the device, the culture chamber is separated from a reagent reservoir by a commercially available microporous membrane, and thus reagents are exchanged between the reservoir and the culture chamber by diffusion only. Using this capability, we verify that the mammospheres are enriched for tumor initiating cells by staining aldehyde dehydrogenase activity, a cancer stem cell marker. To the best of our knowledge, this is the first assay that enables the direct observation of tumor-initiating cells within a suspended mammosphere.

State-of-the-Art Review: Sex Hormone Therapy in Trauma-Hemorrhage.

ABSTRACT: Trauma-hemorrhage is the leading cause of prehospital and early in-hospital deaths, while also significantly contributing to the later development of multisystem organ dysfunction/failure and sepsis. Common and advanced resuscitative methods would potentially demonstrate benefits in the prehospital setting; however, they face a variety of barriers to application and implementation. Thus, a dialogue around a novel adjunct has arisen, sex hormone therapy. Proposed candidates include estradiol and its derivatives, metoclopramide hydrochloride/prolactin, dehydroepiandrosterone, and flutamide; with each having demonstrated a range of salutary effects in several animal model studies. Several retrospective analyses have observed a gender-based dimorphism in mortality following trauma-hemorrhage, thus suggesting that estrogens contribute to this pattern. Trauma-hemorrhage animal models have shown estrogens offer protective effects to the cardiovascular, pulmonary, hepatic, gastrointestinal, and immune systems. Additionally, a series of survival studies utilizing 17α-ethinylestradiol-3-sulfate, a potent, water-soluble synthetic estrogen, have demonstrated a significant survival benefit and beneficial effects on cardiovascular function. This review presents the findings of retrospective clinical studies, preclinical animal studies, and discusses how and why 17α-ethinylestradiol-3-sulfate should be considered for investigation within a prospective clinical trial.

Factors Associated With Increased Mortality in Severe Abdominopelvic Injury.

BACKGROUND: Associated injuries are thought to increase mortality in patients with severe abdominopelvic trauma. This study aimed to identify clinical factors contributing to increased mortality in patients with severe abdominopelvic trauma, with the hypothesis that a greater number of concomitant injuries would result in increased mortality. METHODS: This was a retrospective review of the Trauma Quality Improvement Program (TQIP) database of patients ≥ 18 years with severe abdominopelvic trauma defined as having an abdominal Abbreviated Injury Score (AIS) ≥ 3 with pelvic fractures and/or iliac vessel injury (2015-2017). Primary outcome was in-hospital mortality based on concomitant body region injuries. Secondary outcomes included mortality at 6 h, 6 to 24 h, and after 24 h based on concomitant injuries, procedures performed, and transfusion requirements. RESULTS: A total of 185,257 patients were included in this study. Survivors had more severely injured body regions than non-survivors (4 vs. 3, P < 0.001). Among those who died within 6 h, 28.5% of patients required a thoracic procedure and 43% required laparotomy compared to 6.3% and 22.1% among those who died after 24 h (P < 0.001). Head AIS ≥ 3 was the only body region that significantly contributed to overall mortality (OR 1.26, P < 0.001) along with laparotomy (OR 3.02, P < 0.001), neurosurgical procedures (2.82, P < 0.001) and thoracic procedures (2.28, P < 0.001). Non-survivors who died in < 6 h and 6-24 h had greater pRBC requirements than those who died after 24 h (15.5 and 19.5 vs. 8 units, P < 0.001). CONCLUSION: Increased number of body regions injured does not contribute to greater mortality. Uncontrolled noncompressible torso hemorrhage rather than the burden of concomitant injuries is the major contributor to the high mortality associated with severe abdominopelvic injury.

Open chest selective aortic arch perfusion vs open cardiac massage as a means of perfusion during in exsanguination cardiac arrest: a comparison of coronary hemodynamics in swine.

AIM: To describe and compare the aortic-right atrial pressure (AoP-RAP) gradients and mean coronary perfusion pressures (CPPs) generated during open chest selective aortic arch perfusion (OCSAAP) with those generated during open cardiac massage (OCM) in hypovolemic swine. METHODS: Ten male Hanford swine utilized in a prior poly-trauma study were included in the study. Animals were rendered hypovolemic via a 30% volume bleed. Upon confirmation of death, animals underwent immediate clamshell thoracotomy and aortic cross-clamping followed by 5 min of OCM. A catheter suitable for OCSAAP was then inserted into the aorta and animals underwent 1 min of OCSAAP at a rate of 10 mL/kg/min. Aortic and right atrial pressures were recorded continuously using solid-state blood pressure catheters. Representative 10-s intervals from each resuscitation method were extracted. Hemodynamic parameters including AoP-RAP gradients and CPPs were calculated and compared. RESULTS: At baseline, time from death to intervention was significantly shorter for OCM. However, mean CPPs and AoP-RAP gradients were significantly higher in animals undergoing OCSAAP. 98% of OCSAAP segments had a mean CPP > 15, compared to 35% of OCM intervals. While OCM had a significant negative correlation between time to intervention and maximum CPP, this correlation was not significant for OCSAAP. CONCLUSION: OCSAAP generates favorable and potentially time-resistant pressure gradients when compared to those generated by OCM. Further investigation of the technique of OCSAAP is warranted, as it may have potential utility as a therapy during resuscitative thoracotomy (RT).

Characterization of cerebral blood flow during open cardiac massage in swine: Effect of volume status.

Introduction: Patients in cardiac arrest treated with resuscitative thoracotomy and open cardiac massage (OCM) have high rates of mortality with poor neurological outcomes. The aim of this study is to quantitate cerebral perfusion during OCM using computed tomography perfusion (CTP) imaging in a swine model of normo- and hypovolemia. Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Cerebral blood flow (CBF; ml/100 g of brain) and time to peak (TTP; s) were measured. Animals were then euthanized by exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group) and subjected to a clamshell thoracotomy, aortic cross clamping, OCM, and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCoPP; mmHg) were collected and % CoPP > 15 mmHg (% CoPP; s) calculated post hoc. Results: Normovolemic animals (n = 5) achieved superior pCoPP compared to the hypovolemic animals (n = 5) pCoPP (39.3 vs. 12.3, p < 0.001) and % CoPP (14.5 ± 1.9 vs. 30.9 ± 6.5, p < 0.001). CTP acquisition was successful and TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs. 10.8 vs. 14.8, p = 0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs. 4.9 ± 6.0, p = 0.73) which was significantly lower than baseline values (51.9 ± 12.1, p < 0.001). Conclusion: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.

A swine model of reproducible timed induction of peripheral arterial shunt failure: Developing warning signs of imminent shunt failure.

Temporary intravascular shunts are used to maintain perfusion in injured vessels, although failure can be unpredictable and lead to significant morbidity. The aim of the present study was to develop a dose- and timing-controlled swine model of intrinsic shunt failure to facilitate the development of a warning system for impending failure. Ten Yorkshire swine (weight, 56.6 ± 4.2 kg) underwent bilateral Argyle shunt (Cardinal Health, Dublin, OH) placement in the external iliac arteries, with proximal cannulation of the circumflex iliac arteries for infusion of thrombin. The thrombin infusion was randomized to the left or right side for 5000 vs 10,000 U/h. The 5000-U/h group required 2.1 times as long as the 10,000-U/h group to reach failure (mean, 21.8 minutes vs 46.4 minutes; P < .0001), as shown by a Kaplan-Meier survival analysis (log-rank P < .0001). However, the 5000-U/h group required the same total amount of thrombin (mean, 3752 ± 856 U; P = .57). Thus, time- and/or thrombin dose-controlled induction of shunt failure is technically feasible. Furthermore, in the final 15 minutes before failure, the flow was similar between the two groups (P > .05), and the slope of the flow curve became more negative the closer the model was to failure. Overall, this model could be used to develop an alert system to predict for impending shunt failure or the need for intervention.

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.

An estrogen (17α-ethinyl estradiol-3-sulfate) reduces mortality in a swine model of multiple injuries and hemorrhagic shock.

BACKGROUND: Although 17α-ethinyl estradiol-3-sulfate (EES) reduces mortality in animal models of controlled hemorrhage, its role in a clinically relevant injury model is unknown. We assessed the impact of EES in a swine model of multiple injuries and hemorrhage. METHODS: The study was performed under Good Laboratory Practice, with 30 male uncastrated swine (25-50 kg) subjected to tibial fracture, pulmonary contusion, and 30% controlled hemorrhage for an hour. Animals were randomized to one of five EES doses: 0 (control), 0.3, 1, 3, and 5 mg/kg, administered postinjury. Subjects received no resuscitation and were observed for 6 hours or until death. Survival data were analyzed using Cox-proportional hazard regression. Left ventricular pressure-volume loops were used to derive preload recruitable stroke work as a measure of cardiac inotropy. Immediate postinjury preload recruitable stroke work values were compared with values at 1 hour post-drug administration. RESULTS: Six-hour survival for the 0, 0.3, 1, 3, and 5 mg/kg groups was 0%, 50%, 33.3%, 16.7%, and 0%, respectively. Following Cox regression, the hazard (95% confidence interval) of death was significantly reduced in the 0.3 (0.22 [0.05-0.93]) and 1 (0.24 [0.06-0.89]) mg/kg groups but not the 3 (0.49 [0.15-1.64]) and 5 (0.46 [0.14-1.47]) mg/kg groups. Mean survival time was significantly extended in the 1 mg/kg group (246 minutes) versus the 0 mg/kg group (96 minutes) (p = 0.04, t test). At 1 hour post-drug administration, inotropy was significantly higher than postinjury values in the 0.3 and 1 mg/kg groups (p = 0.003 and p < 0.001, respectively). Inotropy was unchanged in the 3 and 5 mg/kg groups but significantly depressed in the control (p = 0.022). CONCLUSION: Administration of EES even in the absence of fluid resuscitation reduces mortality and improves cardiac inotropy in a clinically relevant swine model of multiple injuries and hemorrhage. These findings support the need for a clinical trial in human trauma patients.

Automatic Hemorrhage Detection From Color Doppler Ultrasound Using a Generative Adversarial Network (GAN)-Based Anomaly Detection Method.

Hemorrhage control has been identified as a priority focus area both for civilian and military populations in the United States because exsanguination is the most common cause of preventable death in hemorrhagic injury. Non-compressible torso hemorrhage (NCTH) has high mortality rate and there are currently no broadly available therapies for NCTH outside of a surgical room environment. Novel therapies, which include High Intensity Focused Ultrasound (HIFU) have emerged as promising methods for hemorrhage control as they can non-invasively cauterize bleeding tissue deep within the body without injuring uninvolved regions. A major challenge in the application of HIFU with color Doppler US guidance is the interpretation and optimization of the blood flow images in real-time to identify the hemorrhagic focus. Today, this task requires an expert sonographer, limiting the utility of this therapy in non-clinical environments. In this work, we investigated the feasibility of an automated hemorrhage detection method using a Generative Adversarial Network (GAN) for anomaly detection that learns a manifold of normal blood flow variability and subsequently identifies anomalous flow patterns that fall outside the learned manifold. As an initial feasibility study, we collected ultrasound color Doppler images of femoral arteries in an animal model of vascular injury (N = 11 pigs). Velocity information of the blood flow were extracted from the color Doppler images that were used for training and testing the anomaly detection network. Normotensive images from 8 pigs were used for training, and testing was performed on normotensive, immediately after injury, 10 minutes post-injury and 30 minutes post-injury images from 3 other pigs. The residual images or the reconstructed error maps show promise in detecting hemorrhages with an AUC of 0.90, 0.87, 0.62 immediately, 10 minutes post-injury and 30 minutes post-injury respectively with an overall AUC of 0.83.

Development of a computed tomography perfusion protocol to support large animal resuscitation research.

BACKGROUND: Adequate cerebral perfusion is crucial for a positive neurological outcome in trauma; however, it is difficult to characterize in the acute setting with noninvasive methods. Intra-arterial computed tomography perfusion may offer a solution. The aim of this study was to develop an intra-arterial computed tomography perfusion protocol for resuscitation research. METHODS: The study examined intra-arterial contrast administration for computed tomography perfusion (CTP) acquisition. It consisted of three phases: intra-arterial contrast dose finding, evaluation of reproducibility, and evaluation during hypotension. Blood pressure and laser Doppler flow data were collected. In phase 1, animals underwent CTPs using several intra-arterial contrast injection protocols. In phase 2, animals underwent two CTPs 7 hours apart using the 2.5 mL/s for 3-second protocol. In phase 3, animals underwent CTPs at several pressures following a computer-controlled bleed including euvolemia and at systolic pressures of 60, 40, and 20 mm Hg. Phase 1 CTPs were evaluated for contrast-to-noise ratio. In phase 2, CTPs were compared within each animal and with laser Doppler flow using linear regression. Phase 3 CTPs were graphed against systolic pressure and fitted with a nonlinear fit. RESULTS: The protocol using 2.5mL/s for 3 seconds was optimal, demonstrating a contrast-to-noise ratio of 40.1 and a superior arterial input function curve compared with the 1 mL/s bolus. Cerebral blood flow demonstrated high concordance between baseline and end of study CTPs (R2 = 0.82, p < 0.001). Cerebral blood flow also compared moderately well against laser Doppler flow during 8 (R2 = 0.53, p = 0.03); however, laser Doppler flow did not perform well during hypovolemia, and the favorable concordance was not maintained (R2 = 0.45, p = 0.06). Cerebral blood flow was graphed against systolic blood pressure and fitted with a nonlinear fit (R2 = 0.95, p = 0.003). CONCLUSION: Computed tomography perfusion using intra-arterial contrast injection may offer a novel alternative to traditional CTP protocols that could prove a useful additional tool in the setting of resuscitation research.

Development of a Swine Polytrauma Model in the Absence of Fluid Resuscitation.

BACKGROUND: In locations in which access to resuscitative therapy may be limited, treating polytraumatized patients present a challenge. There is a pressing need for adjuncts that can be delivered in these settings. To assess these adjuncts, a model representative of this clinical scenario is necessary. We aimed to develop a hemorrhage and polytrauma model in the absence of fluid resuscitation. MATERIALS AND METHODS: This study consisted of two parts: pulmonary contusion dose-finding (n = 6) and polytrauma with evaluation of varying hemorrhage volumes (n = 6). We applied three, six, or nine nonpenetrating captive bolt-gun discharges to the dose-finding group and obtained computed tomography (CT) images. We segmented images to assess contusion volumes. We subjected the second group to tibial fracture, pulmonary contusion, and controlled hemorrhage of 20%, 30%, or 40% and observed for 3 hours or until death. We used Kaplan-Meier analysis to assess survival. We also assessed hemodynamic and metabolic parameters. RESULTS: Contusion volumes for three, six, and nine nonpenetrating captive bolt-gun discharges were 24 ± 28, 50 ± 31, and 63 ± 77 cm3, respectively (p = .679). Animals receiving at least six discharges suffered concomitant parenchymal laceration, whereas one of two swine subjected to three discharges had lacerations. Mortality was 100% at 12 and 115 minutes in the 40% and 30% hemorrhage groups, respectively, and 50% at 3 hours in the 20% group. CONCLUSION: This study characterizes a titratable hemorrhage and polytrauma model in the absence of fluid resuscitation. This model can be useful in evaluating resuscitative adjuncts that can be delivered in areas remote to healthcare access.

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.