Blood banking considerations in pediatric trauma.

ABSTRACT: Transfusion of blood products to a hemorrhaging pediatric trauma patient requires seamless partnership and communication between trauma, emergency department, critical care, and transfusion team members. To avoid confusion and delays, understanding of blood banking principles and mutually agreed upon procedures and policies must be regularly updated as knowledge evolves. Because pediatric patients require specialized considerations distinct from those in adults, this brief review covers transfusion principles, policies, and procedures specific to the resuscitation of pediatric trauma patients.

Exploring blood-brain barrier hyperpermeability and potential biomarkers in traumatic brain injury.

Blood-brain barrier breakdown and associated vascular hyperpermeability leads to vasogenic edema in traumatic brain injury (TBI). Tight junctions maintain blood-brain barrier integrity; their disruption in TBI holds significant promise for diagnosis and treatment. A controlled cortical impactor was used for TBI in mouse studies. Blood was collected 1 h after injury and sent for antibody microarray analysis. Twenty human subjects with radiographic evidence of TBI were enrolled and blood collected within 48 h of admission. Control subjects were individuals with nontrauma diagnoses. The subjects were matched by age and gender. Enzyme-linked immunosorbent assays were performed on each TBI and control sample for tight junction-associated proteins (TJPs), inflammatory markers, and S100ß. Plasma was used to conduct in vitro monolayer permeability studies with human brain endothelial cells. S100ß and the TJP occludin were significantly elevated in TBI plasma in both the murine and human studies. Monolayer permeability studies showed increased hyperpermeability in TBI groups. Plasma from TBI subjects increases microvascular hyperpermeability in vitro. TJPs in the blood may be a potential biomarker for TBI.

A Rat Burn Injury Model for Studying Changes in Microvascular Permeability.

The management of burn patients is an extremely complex and clinically challenging for patient care. Aside from the increasing reports of burn injury and morbidity and mortality directly related to it, the pathobiology of burn trauma is not clearly understood. The rat model of burn trauma described here is currently used in research laboratories to study various aspects of burn injury, including vascular dysfunctions. This model demonstrates the infliction of thermal injury in Sprague-Dawley rats using a well-established boiled water approach. We have utilized intravital microscopy to examine the microvascular hyperpermeability, the excessive leakage of proteins and fluids from the intravascular space to the extravascular space in mesenteric postcapillary venules using this model. An increase in microvascular permeability is a strong indicator of microvascular dysfunctions leading to tissue edema in burn trauma.

Implementation of a standardized handoff protocol for post-operative admissions to the surgical intensive care unit.

BACKGROUND: The transfer of critically ill patients from the operating room (OR) to the surgical intensive care unit (SICU) involves handoffs between multiple providers. Incomplete handoffs lead to poor communication, a major contributor to sentinel events. Our aim was to determine whether handoff standardization led to improvements in caregiver involvement and communication. METHODS: A prospective intervention study was designed to observe thirty one patient handoffs from OR to SICU for 49 critical parameters including caregiver presence, peri-operative details, and time required to complete key steps. Following a six month implementation period, thirty one handoffs were observed to determine improvement. RESULTS: A significant improvement in presence of physician providers including intensivists and surgeons was observed (p = 0.0004 and p < 0.0001, respectively). Critical details were communicated more consistently, including procedure performed (p = 0.0048), complications (p < 0.0001), difficult airways (p < 0.0001), ventilator settings (p < 0.0001) and pressor requirements (p = 0.0134). Conversely, handoff duration did not increase significantly (p = 0.22). CONCLUSIONS: Implementation of a standardized protocol for handoffs between OR and SICU significantly improved caregiver involvement and reduced information omission without affecting provider time commitment.

Survey of American College of Surgeons Committee on trauma members on firearm injury: Consensus and opportunities.

BACKGROUND: In the United States, there is a perceived divide regarding the benefits and risks of firearm ownership. The American College of Surgeons Committee on Trauma Injury Prevention and Control Committee designed a survey to evaluate Committee on Trauma (COT) member attitudes about firearm ownership, freedom, responsibility, physician-patient freedom and policy, with the objective of using survey results to inform firearm injury prevention policy development. METHODS: A 32-question survey was sent to 254 current U.S. COT members by email using Qualtrics. SPSS was used for χ exact tests and nonparametric tests, with statistical significance being less than 0.05. RESULTS: Our response rate was 93%, 43% of COT members have firearm(s) in their home, 88% believe that the American College of Surgeons should give the highest or a high priority to reducing firearm-related injuries, 86% believe health care professionals should be allowed to counsel patients on firearms safety, 94% support federal funding for firearms injury prevention research. The COT participants were asked to provide their opinion on the American College of Surgeons initiating advocacy efforts and there was 90% or greater agreement on 7 of 15 and 80% or greater on 10 of 15 initiatives. CONCLUSION: The COT surgeons agree on: (1) the importance of formally addressing firearm injury prevention, (2) allowing federal funds to support research on firearms injury prevention, (3) retaining the ability of health care professionals to counsel patients on firearms-related injury prevention, and (4) the majority of policy initiatives targeted to reduce interpersonal violence and firearm injury. It is incumbent on trauma and injury prevention organizations to leverage these consensus-based results to initiate prevention, advocacy, and other efforts to decrease firearms injury and death. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level I; therapeutic care, level II.

Maternal pre-eclampsia as a risk factor for necrotizing enterocolitis.

OBJECTIVE: Similar pro-inflammatory responses are present in pre-eclampsia (PE) and necrotizing enterocolitis (NEC). We hypothesized that maternal PE is an independent risk factor for the development of NEC. METHODS: A retrospective database of all live births (2008-2011) at a tertiary center was constructed. Infant and maternal characteristics were gathered. Babies born to mothers with or without PE were compared. Data were analyzed using Mann-Whitney U, Pearson's χ(2), binary logistic regression and relative risks. RESULTS: Incidence of NEC was 1.5% in non-PE and 4.6% in the PE group (p < 0.001), but once controlled for gestational age and birth weight, the difference lost statistical significance. PE babies were more frequently preterm (41.4% versus 14.5%, p < 0.001) and had intrauterine growth restriction (IUGR) (10.2% versus 6.3%, p < 0.001). Within preterm babies, 9.0% of non-PE and 10.8% of PE babies developed NEC (p = 0.25). Effect of PE was significant in sub-group of IUGR babies, with NEC in 1.5% of non-PE and 13.6% in PE babies (p < 0.001). CONCLUSIONS: Maternal PE is an independent risk factor for the development of NEC in some sub-groups of babies, most notably with IUGR. Fetal hypoxia caused by abnormal placentation in PE leads to restricted growth, and may be the underlying mechanism that predisposes the newborn to NEC.

Melatonin Preserves Blood-Brain Barrier Integrity and Permeability via Matrix Metalloproteinase-9 Inhibition.

Microvascular hyperpermeability that occurs at the level of the blood-brain barrier (BBB) often leads to vasogenic brain edema and elevated intracranial pressure following traumatic brain injury (TBI). At a cellular level, tight junction proteins (TJPs) between neighboring endothelial cells maintain the integrity of the BBB via TJ associated proteins particularly, zonula occludens-1 (ZO-1) that binds to the transmembrane TJPs and actin cytoskeleton intracellularly. The pro-inflammatory cytokine, interleukin-1ß (IL-1ß) as well as the proteolytic enzymes, matrix metalloproteinase-9 (MMP-9) are key mediators of trauma-associated brain edema. Recent studies indicate that melatonin a pineal hormone directly binds to MMP-9 and also might act as its endogenous inhibitor. We hypothesized that melatonin treatment will provide protection against TBI-induced BBB hyperpermeability via MMP-9 inhibition. Rat brain microvascular endothelial cells grown as monolayers were used as an in vitro model of the BBB and a mouse model of TBI using a controlled cortical impactor was used for all in vivo studies. IL-1ß (10 ng/mL; 2 hours)-induced endothelial monolayer hyperpermeability was significantly attenuated by melatonin (10 µg/mL; 1 hour), GM6001 (broad spectrum MMP inhibitor; 10 µM; 1 hour), MMP-9 inhibitor-1 (MMP-9 specific inhibitor; 5 nM; 1 hour) or MMP-9 siRNA transfection (48 hours) in vitro. Melatonin and MMP-9 inhibitor-1 pretreatment attenuated IL-1ß-induced MMP-9 activity, loss of ZO-1 junctional integrity and f-actin stress fiber formation. IL-1ß treatment neither affected ZO-1 protein or mRNA expression or cell viability. Acute melatonin treatment attenuated BBB hyperpermeability in a mouse controlled cortical impact model of TBI in vivo. In conclusion, one of the protective effects of melatonin against BBB hyperpermeability occurs due to enhanced BBB integrity via MMP-9 inhibition. In addition, acute melatonin treatment provides protection against BBB hyperpermeability in a mouse model of TBI indicating its potential as a therapeutic agent for brain edema when established in humans.

Predicting and enhancing American Board of Surgery In-Training Examination performance: does writing questions really help?

BACKGROUND: The generative learning model posits that individuals remember content they have generated better than materials created by others. The goals of this study were to evaluate question generation as a study method for the American Board of Surgery In-Training Examination (ABSITE) and determine whether practice test scores and other data predict ABSITE performance. METHODS: Residents (n = 206) from 6 general surgery programs were randomly assigned to one of the two study conditions. One group wrote questions for practice examinations. All residents took 2 practice examinations. RESULTS: There was not a significant effect of writing questions on ABSITE score. Practice test scores, United States Medical Licensing Examination Step 1 scores, and previous ABSITE scores were significantly correlated with ABSITE performance. CONCLUSIONS: The generative learning model was not supported. Performance on practice tests and other data can be used for early identification of residents at risk of performing poorly on the ABSITE.

Tissue inhibitor of metalloproteinase-2 inhibits burn-induced derangements and hyperpermeability in microvascular endothelial cells.

BACKGROUND: Burns induce microvascular hyperpermeability. We hypothesize that this occurs partly through an imbalance between matrix metalloproteinases (MMPs) and endogenous MMP inhibitors such as tissue inhibitors of metalloproteinases (TIMPs), and that such derangements can be attenuated with the use of TIMP-2. METHOD: Rats underwent either sham or burn: serum and tissue were collected. Western blot was used to examine MMP-9 and TIMP-2 levels and MMP activity was assayed from lung tissue. Rat lung microvascular endothelial cells were used to assess monolayer permeability and evaluate the adherens junction proteins ß-catenin, vascular endothelial cadherin and filamentous actin after exposure to burn serum ± TIMP-2. RESULTS: Lung tissue from burn animals showed increased MMP activity, decreased levels of TIMP-2, and no difference in levels of active MMP-9 in burn vs control groups. Burn serum increased monolayer permeability, damaged adherens junction proteins, and incited actin stress fiber formation; TIMP-2 attenuated these derangements. CONCLUSIONS: Burns may lower TIMP-2 levels and increase MMP activity and that TIMP-2 application in vitro may attenuate burn-induced hyperpermeability and decreases damage to endothelial structural proteins. These links warrant further investigation.

Doxycycline Attenuates Lipopolysaccharide-Induced Microvascular Endothelial Cell Derangements.

INTRODUCTION: Lipopolysaccharide (LPS) is known to induce vascular derangements. The pathophysiology involved therein is unknown, but matrix metalloproteinases (MMPs) may be an important mediator. We hypothesized that in vitro LPS provokes vascular permeability, damages endothelial structural proteins, and increases MMP activity; that in vivo LPS increases permeability and fluid requirements; and that the MMP inhibitor doxycycline mitigates such changes. METHODS: Rat lung microvascular endothelial cells were divided into four groups: control, LPS, LPS plus doxycycline, and doxycycline. Permeability, structural proteins ß-catenin and Filamentous-actin, and MMP-9 activity were examined. Sprauge Dawley rats were divided into sham, IV LPS, and IV LPS plus IV doxycycline groups. Mesenteric postcapillary venules were observed. Blood pressure was measured as animals were resuscitated and fluid requirements were compared. Statistical analysis was conducted using Student's t-test and ANOVA. RESULTS: In vitro LPS increased permeability, damaged adherens junctions, induced actin stress fiber formation, and increased MMP-9 enzyme activity. In vivo, IV LPS administration induced vascular permeability. During resuscitation, significantly more fluid was necessary to maintain normotension in the IV LPS group. Doxycycline mitigated all derangements observed. CONCLUSIONS: We conclude that LPS increases permeability, damages structural proteins, and increases MMP-9 activity in endothelial cells. Additionally, endotoxemia induces hyperpermeability and increases the amount of IV fluid required to maintain normotension in vivo. Doxycycline mitigates such changes both in vitro and in vivo. Our findings illuminate the possible role of matrix metalloproteinases in the pathophysiology of lipopolysaccharide-induced microvascular hyperpermeability and pave the way for better understanding and treatment of this process.

Blood-brain barrier dysfunction following traumatic brain injury.

Traumatic brain injury is a serious cause of morbidity and mortality worldwide. After traumatic brain injury, the blood-brain barrier, the protective barrier between the brain and the intravascular compartment, becomes dysfunctional, leading to leakage of proteins, fluid, and transmigration of immune cells. As this leakage has profound clinical implications, including edema formation, elevated intracranial pressure and decreased perfusion pressure, much interest has been paid to better understanding the mechanisms responsible for these events. Various molecular pathways and numerous mediators have been found to be involved in the intricate process of regulating blood-brain barrier permeability following traumatic brain injury. This review provides an update to the existing knowledge about the various pathophysiological pathways and advancements in the field of blood-brain barrier dysfunction and hyperpermeability following traumatic brain injury, including the role of various tight junction proteins involved in blood-brain barrier integrity and regulation. We also address pitfalls of existing systems and propose strategies to improve the various debilitating functional deficits caused by this progressive epidemic.

Tumor necrosis factor-α disruption of brain endothelial cell barrier is mediated through matrix metalloproteinase-9.

Traumatic brain injuries cause vascular hyperpermeability. Tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and caspase-3 may be important in these processes but the relationship between them has not been investigated. We hypothesized that TNF-α regulates caspase-3-mediated hyperpermeability and blood brain barrier damage and hyperpermeability directly or indirectly via activation of MMP-9. To test this, rat brain microvascular endothelial cells were treated with TNF-α with or without inhibition of MMP-9. Monolayer permeability was measured, zonula occludens-1 and F-actin configuration were examined, and MMP-9 and caspase-3 activities were quantified. TNF-α increased monolayer permeability, damaged zonula occludens-1, induced filamentous-actin stress fiber formation, and increased both MMP-9 and caspase-3 activities. Inhibition of MMP-9 attenuated these changes. These data highlight a novel link between TNF-α and MMP-9 and show that TNF-α regulated caspase-3-mediated hyperpermeability and vascular damage may be linked to MMP-9 in vitro. These findings augment the understanding of traumatic brain injury and pave the way for improved treatment.

Melatonin inhibits thermal injury-induced hyperpermeability in microvascular endothelial cells.

BACKGROUND: Burns induce systemic inflammatory reactions and vascular hyperpermeability. Breakdown of endothelial cell adherens junctions is integral in this process, and reactive oxygen species (ROS) and proteolytic enzymes such as matrix metalloproteinase-9 (MMP-9) play pivotal roles therein. Outside trauma, melatonin has shown to exhibit anti-MMP activity and to be a powerful antioxidant. Consequently, we hypothesized that burn-induced junctional damage and hyperpermeability could be attenuated with melatonin. METHODS: Sprague-Dawley rats were assigned to sham or burn groups. Fluorescein isothiocyanate-bovine albumin was administered intravenously. Venules were examined with intravital microscopy; fluorescence intensities were measured intravascularly and extravascularly. Serum was collected. Rat lung microvascular endothelial cells were grown as monolayers and divided into four groups: sham serum and burn serum with and without melatonin pretreatment. Fluorescein isothiocyanate-bovine albumin flux was measured. Immunofluorescence for adherens junction proteins and staining for actin were performed, and images were captured. Cells were grown on 96 well plates, and ROS species generation following application of burn and sham serum was analyzed with and without melatonin. Statistical analysis was conducted with the Student's t test. RESULTS: Intravital microscopy data revealed an increase in vascular hyperpermeability following burn (p < 0.05). Monolayer permeability was increased with burn serum (p < 0.05); this was attenuated with melatonin (p < 0.05). Immunofluorescence showed damage of rat lung microvascular endothelial cell adherens junctions with burn serum exposure, and melatonin restored integrity. Rhodamine phalloidin staining showed filamentous actin stress fiber formation after burn serum application, and melatonin decreased this. Burn serum significantly increased ROS species generation (p < 0.05), and melatonin negated this (p < 0.05). CONCLUSION: Burns damage endothelial adherens junctions and induce microvascular hyperpermeability; melatonin attenuates this process. This insight into the mechanisms of burn-induced fluid leak suggests the role of ROS and MMP-9 but more importantly hints at the possibility of new treatments to combat vascular hyperpermeability in burns.

Surgeons' performance during critical situations: competence, confidence, and composure.

BACKGROUND: Little is known about surgeons' performance during critical situations. We hypothesized that there are methods and techniques used by surgeons that facilitate performance during critical situations. METHODS: Surgical faculty and senior general surgery residents from a single academic health center were surveyed. RESULTS: Twenty-six surgeons participated. With respect to critical situations, the surgeons felt confident (96%), expected to be successful (96%), and most did not find these situations particularly stressful (62%). The majority reported using learned skills (92%) and agree their skills can be taught (82%). Practice and preparation were reported as very important (89%). A majority use pre-emptive visualization (68%). Competence, confidence, composure, preparation, and experience were most commonly listed as characteristics or behaviors that should be encouraged in aspiring surgeons. Anger, panic, indecision, fear, and chaos were the most commonly listed characteristics that should be discouraged. CONCLUSIONS: Surgeons' response to performance under pressure is complex; however, surgeons report using simple, learned techniques that seem to be targeted toward eliminating the "fight or flight" sympathetic nervous system response.