Muscle Flap Technique Safe for On-ECMO Congenital Diaphragmatic Hernia Repair.

INTRODUCTION: Prosthetic patches (patch) and muscle flaps (flap) are techniques used for repair of congenital diaphragmatic hernia (CDH) with a large defect unamenable to primary closure. We hypothesized that the flap technique for CDH repair while on extra-corporeal membrane oxygenation (on-ECMO) would have decreased bleeding complications compared to patch due to the hemostatic advantage of native tissue. METHODS: A single-center retrospective comparative study of patients who underwent on-ECMO CDH repair between 2008 and 2022 was performed. RESULTS: Fifty-two patients met inclusion criteria: 18 patch (34.6%) and 34 flap (65.4%). There was no difference in CDH severity between groups. On univariate analysis, reoperation for surgical bleeding was lower following flap repair compared to patch (23.5% vs 55.6%, respectively; p = 0.045), 48-h postoperative blood product transfusion was lower after flap repair (132 mL/kg vs 273.5 mL/kg patch; p = 0.006), and two-year survival was increased in the flap repair group compared to patch (53.1% vs 17.7%, respectively; p = 0.036). On multivariate analysis adjusting for CDH side, day on ECMO repaired, and day of life CDH repaired, flap repair was significantly associated with lower five-day postoperative packed red blood cell transfusion amount, improved survival to hospital discharge, and improved two-year survival. CONCLUSIONS: Our experience suggests that the muscle flap technique for on-ECMO CDH repair is associated with reduced bleeding complications compared to prosthetic patch repair, which may in part be responsible for the improved survival seen in the flap repair group. These results support the flap repair technique as a favored method for on-ECMO CDH repair. LEVEL OF EVIDENCE: Level III.

Cerium oxide nanoparticle conjugation to microRNA-146a mechanism of correction for impaired diabetic wound healing.

Diabetic wounds represent a significant healthcare burden and are characterized by impaired wound healing due to increased oxidative stress and persistent inflammation. We have shown that CNP-miR146a synthesized by the conjugation of cerium oxide nanoparticles (CNP) to microRNA (miR)-146a improves diabetic wound healing. CNP are divalent metal oxides that act as free radical scavenger, while miR146a inhibits the pro-inflammatory NFκB pathway, so CNP-miR146a has a synergistic role in modulating both oxidative stress and inflammation. In this study, we define the mechanism(s) by which CNP-miR146a improves diabetic wound healing by examining immunohistochemical and gene expression analysis of markers of inflammation, oxidative stress, fibrosis, and angiogenesis. We have found that intradermal injection of CNP-miR146a increases wound collagen, enhances angiogenesis, and lowers inflammation and oxidative stress, ultimately promoting faster closure of diabetic wounds.

Lung function improves after delayed treatment with CNP-miR146a following acute lung injury.

Acute respiratory distress syndrome (ARDS) is a highly morbid pulmonary disease characterized by hypoxic respiratory failure. Its pathogenesis is characterized by unrestrained oxidative stress and inflammation, with long-term sequelae of pulmonary fibrosis and diminished lung function. Unfortunately, prior therapeutic ARDS trials have failed and therapy is limited to supportive measures. Free radical scavenging cerium oxide nanoparticles (CNP) conjugated to the anti-inflammatory microRNA-146a (miR146a), termed CNP-miR146a, have been shown to prevent acute lung injury in a pre-clinical model. In this study, we evaluated the potential of delayed treatment with CNP-miR146a at three or seven days after injury to rescue the lung from acute injury. We found that intratracheal CNP-miR146a administered three days after injury lowers pulmonary leukocyte infiltration, reduce inflammation and oxidative stress, lower pro-fibrotic gene expression and collagen deposition in the lung, and ultimately improve pulmonary function.

Cerium oxide nanoparticle delivery of microRNA-146a for local treatment of acute lung injury.

Acute respiratory distress syndrome (ARDS) is a devastating pulmonary disease with significant in-hospital mortality and is the leading cause of death in COVID-19 patients. Excessive leukocyte recruitment, unregulated inflammation, and resultant fibrosis contribute to poor ARDS outcomes. Nanoparticle technology with cerium oxide nanoparticles (CNP) offers a mechanism by which unstable therapeutics such as the anti-inflammatory microRNA-146a can be locally delivered to the injured lung without systemic uptake. In this study, we evaluated the potential of the radical scavenging CNP conjugated to microRNA-146a (termed CNP-miR146a) in preventing acute lung injury (ALI) following exposure to bleomycin. We have found that intratracheal delivery of CNP-miR146a increases pulmonary levels of miR146a without systemic increases, and prevents ALI by altering leukocyte recruitment, reducing inflammation and oxidative stress, and decreasing collagen deposition, ultimately improving pulmonary biomechanics.

Nanosilk Increases the Strength of Diabetic Skin and Delivers CNP-miR146a to Improve Wound Healing.

Diabetes mellitus is a metabolic disorder associated with properties and an increased risk of chronic wounds due to sustained pro-inflammatory response. We have previously of radical scavenging cerium oxide nanoparticles (CNP) conjugated to the anti-inflammatory microRNA (miR)-146a, termed CNP-miR146a, improves diabetic wound healing by synergistically lowering oxidative stress and inflammation, and we sought to evaluate this treatment in a topical application. Silk fibroin is a biocompatible polymer that can be fabricated into nanostructures, termed nanosilk. Nanosilk is characterized by a high strength-to-density ratio and an ability to exhibit strain hardening. We therefore hypothesized that nanosilk would strengthen the biomechanical properties of diabetic skin and that nanosilk solution could effectively deliver CNP-miR146a to improve diabetic wound healing. The ability of nanosilk to deliver CNP-miR146a to murine diabetic wounds and improve healing was assessed by the rate of wound closure and inflammatory gene expression, as well as histologic analysis. The effect of nanosilk on the properties of human diabetic skin was evaluated by testing the biomechanical properties following topical application of a 7% nanosilk solution. Diabetic murine wounds treated with topical nanosilk and CNP-miR146a healed by day 14.5 compared to day 16.8 in controls (p = 0.0321). Wounds treated with CNP-miR146a had higher collagen levels than controls (p = 0.0126) with higher pro-fibrotic gene expression of TGFß-1 (p = 0.0092), Col3α1 (p = 0.0369), and Col1α2 (p = 0.0454). Treatment with CNP-miR146a lowered pro-inflammatory gene expression of IL-6 (p = 0.0488) and IL-8 (p = 0.0009). Treatment of human diabetic skin with 7% nanosilk solution resulted in significant improvement in maximum load and modulus (p < 0.05). Nanosilk solution is able to strengthen the biomechanical properties of diabetic skin and can successfully deliver CNP-miR146a to improve diabetic wound healing through inhibition of pro-inflammatory gene signaling and promotion of pro-fibrotic processes.

Determining maternal risk factors for gastroschisis using colorado's birth registry database.

AIM OF STUDY: Gastroschisis is a congenital abdominal wall defect which results in herniation of abdominal contents. The objective of this study was to determine the maternal risk factors for gastroschisis in Colorado. METHODS: A case-control study was performed using the Birth Registry database from 2007 to 2016. The outcome was gastroschisis, and the main variable was maternal age which was divided into <21, 21-30, and >30 years of age. Descriptive analysis, bivariate analysis, and logistic regression was performed. RESULTS: There were 236 cases of gastroschisis compared to 944 controls. Maternal age did vary significantly between groups (23.4 ±â€¯5 years (cases) vs. 28.7 ±â€¯5.9 years (controls); p < 0.0001). Unadjusted analysis demonstrated that those with young maternal age (<21 years of age) had a 14.14 (95% CI 8.44-23.67) higher odds of gastroschisis compared to those >30 years of age. Independent risk factors for gastroschisis were exposure to prenatal and first trimester cigarettes, prenatal and first trimester alcohol, and chlamydia infection. The odds (4.41, 95% CI 1.36-14.26) of gastroschisis were highest in those with first trimester cigarette exposure and young maternal age (p = 0.03). CONCLUSIONS: Young maternal age, cigarette exposure, alcohol exposure, and chlamydia infection increase the odds of gastroschisis. The interaction between young maternal age and first trimester cigarette exposure significantly increases the odds of gastroschisis. TYPE OF STUDY: Prognosis Study. LEVEL OF EVIDENCE: Level III.

A congenital cystic pulmonary airway malformation occurring together with both an extralobar pulmonary sequestration and an esophageal duplication cyst.

A foregut duplication cyst occurring together with both a congenital cystic pulmonary airway malformation and extralobar pulmonary sequestration is an unusual combination. Prenatal ultrasound, MRI, and postnatal CT are helpful for operative planning. Surgical resection is the definitive management for all three anomalies.

Is Tapering Enteroplasty an Alternative to Resection of Dilated Bowel in Small Intestinal Atresia?

BACKGROUND: Intestinal atresia is a congenital defect resulting in intestinal discontinuity and can be associated with significant morbidity related to intestinal failure. The bowel proximal to the atresia is often significantly dilated and dysfunctional. The treatment approaches of this dilated bowel include resection with primary anastomosis versus tapering enteroplasty with preservation of bowel length. The purpose of this study was to compare these two approaches in regard to bowel function as characterized by the time to full enteral feeding. METHODS: A retrospective review was performed of intestinal atresia repair performed at a tertiary referral pediatric hospital from 2007 to 2017. Length of stay, time to full enteral feeds, and complications were assessed in patients who underwent repair with tapering enteroplasty (n = 8) and compared with those who underwent resection and anastomosis (n = 39). RESULTS: The median age at surgery, gender distribution, weeks gestational age (WGA), location of the atresia, and comorbidities were similar between the two groups. Overall, there was no statistically significant difference in length of stay and time to full enteral feeds between groups. Three of eight (38%) patients in the tapered group and five of 39 patients (13%; P = 0.12) in the nontapered group underwent further surgical exploration because of bowel dysmotility. Factors associated with longer length of hospital stay were abdominal reoperation and WGA, and factors associated with longer time to full enteral feeds were WGA, abdominal reoperation, and gastroschisis. CONCLUSIONS: Tapering enteroplasty at initial operation for intestinal atresias preserves bowel length and has statistically equivalent outcomes to resection and anastomosis in regard to the length of stay and time to full enteral feeds.

Examination of Prenatal Sonographic Findings: Intra-Abdominal Bowel Dilation Predicts Poor Gastroschisis Outcomes.

BACKGROUND: Gastroschisis is an anterior abdominal wall defect with variable outcomes. There are conflicting data regarding the prognostic value of sonographic findings. OBJECTIVES: The aim of this study was to identify prenatal ultrasonographic features associated with poor neonatal outcomes. METHOD: A retrospective review of 55 patients with gastroschisis from 2007 to 2017 was completed. Ultrasounds were reviewed for extra-abdominal intestinal diameter (EAID) and intra-abdominal intestinal diameter (IAID), echogenicity, visceral content within the herniation, amniotic fluid index, defect size, and abdominal circumference (AC). Ultrasound variables were correlated with full enteral feeding and the diagnosis of a complex gastroschisis. RESULTS: Bivariate analysis demonstrated an increased time to full enteral feeds with increasing number of surgeries, EAID, and IAID. Additionally, there was a significant relationship between IAID and AC percentile with the diagnosis of complex gastroschisis. On multivariate analysis, only IAID was significant and increasing diameter had a 2.82 (95% CI 1.02-7.78) higher odds of a longer time to full enteral feeds and a 1.2 (95% CI 1.05-1.36) greater odds of the diagnosis of a complex gastroschisis. CONCLUSIONS: Based on these findings, IAID is associated with a longer time to full enteral feeding and the diagnosis of complex gastroschisis.

Injectable, self-healable zwitterionic cryogels with sustained microRNA - cerium oxide nanoparticle release promote accelerated wound healing.

Diabetics are prone to chronic wounds that have slower healing, and methods of accelerating the wound closure and to ensure protection from infections are critically needed. MicroRNA-146a gets dysregulated in diabetic wounds and injection of this microRNA combined with reactive oxygen species-scavenging cerium oxide nanoparticles (CNPs) can reduce inflammation and improve wound healing; however, a better delivery method than intradermal injections is needed. Here we demonstrate a biomaterial system of zwitterionic cryogels (gels formed below freezing temperatures) laden with CNP-miR146a that are topically applicable, injectable, self-healable, and provide sustained release of the therapeutic molecules. These cryogels are comprised of CBMA or SBMA and HEMA, and do not contain chemical crosslinkers. Properties of the gels can be manipulated by changing monomer type and ratio. These materials have demonstrated efficacy and viability in vivo with a diabetic mouse wound healing model. Overall, these materials have a high potential for application in wound treatments due to their ease of production, antifouling characteristics, durability, topical application, and sustained release mechanics. STATEMENT OF SIGNIFICANCE: This work presents the development of zwitterionic cryogels with unique physical properties including injectability and self-healing, that also offer highly sustained release of nanoparticles over time to improve wound healing in a diabetic mouse model. The nanoparticles are made of cerium oxide, which is known to scavenge reactive oxygen species and reduce oxidative stress, and these particles have been further tagged with a microRNA146a that has been shown to reduce inflammation. Zwitterionic materials are known for their superior antifouling properties and good biocompatibility and ability to incorporate bioactive factors. Given these properties, the use of these materials as wound healing dressings would be exciting, yet to date it has been difficult to prolong the release of bioactive factors from them due to their hydrophilicity. Previously we developed zwitterionic cyrogels with very sustained protein release over time, but those materials were quite brittle and difficult to handle. Here, we demonstrate for the first time that by removing the crosslinker molecule from our reaction and polymerizing gels under cryo-conditions, we are able to form zwitterionic cryogels that are injectable, self-healing, and with sustained release profiles. The sustained release of miRNA146a-tagged cerium oxide nanoparticles from these gels is demonstrated to speed up diabetic wound healing time and significantly reduce inflammation.

Mesenchymal stromal cells contract collagen more efficiently than dermal fibroblasts: Implications for cytotherapy.

BACKGROUND: Stem cell therapy is the next generation a well-established technique. Cell therapy with mesenchymal stem cells (MSC) has been demonstrated to enhance wound healing in diabetic mice, at least partly due to improved growth factor production. However, it is unclear whether MSC can biomechanically affect wound closure. Utilizing the well-established cell-populated collagen gel contraction model we investigated the interactions between MSC and the extracellular matrix. METHODS: Murine fetal liver-derived Mesenchymal Stem Cells (MSCs) or fetal Dermal Fibroblasts (DFs) were cultured in cell-populated collagen gels (CPCGs). The effect of cell density, conditioned media, growth factors (TGF-B1, FGF, PDGF-BB), cytoskeletal disruptors (colchicine, cytochalasin-D), and relative hypoxia on gel contraction were evaluated. Finally, we also measured the expression of integrin receptors and some growth factors by MSCs within the contracting gels. RESULTS: Our results show that at different densities, MSCs induced a higher gel contraction compared to DFs. Higher cell density resulted in faster and more complete contraction of CPCGs. Cytoskeletal inhibitors either inhibited or prevented MSC-mediated contraction in a dose dependent fashion. Growth factors, conditioned media from both MSC and DF, and hypoxia all influenced CPCG contraction. DISCUSSION: The results suggest that MSCs are capable of directly contributing to wound closure through matrix contraction, and they are more effective than DF. In addition, this study demonstrates the importance of how other factors such as cell concentration, cytokines, and oxygen tension can provide potential modulation of therapies to correct wound healing impairments.

MOMS Plus: Single-Institution Review of Outcomes for Extended BMI Criteria for Open Fetal Repair of Myelomeningocele.

BACKGROUND: In utero repair has become an accepted therapy to decrease the rate of ventriculoperitoneal shunting and improve neurologic function in select cases of myelomeningocele. The Management of Myelomeningocele Study (MOMS) trial excluded patients with a BMI >35 due to concerns for increased maternal complications and preterm delivery, limiting the population that may benefit from this intervention. OBJECTIVES: The aim of this study was to evaluate outcomes associated with extending the maternal BMI criteria to 40 in open fetal repair of myelomeningocele. METHOD: Retrospective review of fetal closure of myelomeningocele at a quaternary referral center between 2013 and 2016 with maternal BMI ranging from 35 to 40. RESULTS: Eleven patients with a BMI >35 were identified. The average BMI was 37. The average maternal age at the time of evaluation was 27 years. The average gestational age at fetal surgery was 24 weeks. Gestational age at birth was an average of 32 weeks. There was one perinatal death immediately following the fetal intervention. The shunt rate at 1 year was 45% (5/11 patients). CONCLUSIONS: In this single-institution review of expanded BMI criteria for fetal repair of myelomeningocele, we did not observe any adverse maternal outcomes associated with maternal obesity; however, the gestational age at delivery was 2 weeks earlier compared to the MOMS trial.

Differential Expression of Transforming Growth Factor-ß1 Is Associated With Fetal Regeneration After Myocardial Infarction.

BACKGROUND: Global extracellular matrix (ECM)-related gene expression is decreased after myocardial infarction (MI) in fetal sheep when compared with adult sheep. Transforming growth factor (TGF)-ß1 is a key regulator of ECM; therefore we hypothesize that TGF-ß1 is differentially expressed in adult and fetal infarcts after MI. METHODS: Adult and fetal sheep underwent MI via ligation of the left anterior descending coronary artery. Expression of TGF-ß1 and ECM-related genes was evaluated by ovine-specific microarray and quantitative polymerase chain reaction. Fibroblasts from the left ventricle of adult and fetal hearts were treated with TGF-ß1 or a TGF-ß1 receptor inhibitor (LY36497) to evaluate the effect of TGF-ß1 on ECM-related genes. RESULTS: Col1a1, col3a1, and MMP9 expression were increased in adult infarcts 3 and 30 days after MI but were upregulated in fetal infarcts only 3 days after MI. Three days after MI elastin expression was increased in adult infarcts. Despite upregulation in adult infarcts both 3 and 30 days after MI, TGF-ß1 was not upregulated in fetal infarcts at any time point. Inhibition of the TGF-ß1 receptor in adult cardiac fibroblasts decreased expression of col1a1, col3a1, MMP9, elastin, and TIMP1, whereas treatment of fetal cardiac fibroblasts with TGF-ß1 increased expression of these genes. CONCLUSIONS: TGF-ß1 is increased in adult infarcts compared with regenerative, fetal infarcts after MI. Although treatment of fetal cardiac fibroblasts with TGF-ß1 conveys an adult phenotype, inhibition of TGF-ß1 conveys a fetal phenotype to adult cardiac fibroblasts. Decreasing TGF-ß1 after MI may facilitate myocardial regeneration by "fetalizing" the otherwise fibrotic, adult response to MI.

Use of Cerium Oxide Nanoparticles Conjugated with MicroRNA-146a to Correct the Diabetic Wound Healing Impairment.

BACKGROUND: Diabetic wounds have become one of the most challenging public health issues of the 21st century, yet there is no effective treatment available. We have previously shown that the diabetic wound healing impairment is associated with increased inflammation and decreased expression of the regulatory microRNA miR-146a. We have conjugated miR-146a to cerium oxide nanoparticles (CNP-miR146a) to target reactive oxygen species (ROS) and inflammation. This study aimed to evaluate the consequences of CNP-miR146a treatment of diabetic wounds. STUDY DESIGN: Eight-millimeter wounds were created on the dorsal skin of Db/Db mice and treated with PBS or differing concentrations of CNP-mir146a (1; 10; 100; or 1,000 ng) at the time of wounding. Rate of wound closure was measured until the wounds were fully healed. At 4 weeks post-healing, a dumbbell-shaped skin sample was collected, with the healed wound in the center, and an Instron 5942 testing unit was used to measure the maximum load and modulus. RESULTS: Our data showed that diabetic wounds treated with PBS or 1 ng CNP-miR146a took 18 days to heal. Treatment with 10, 100, or 1,000 ng of CNP+miR-146a effectively enhanced healing, and wounds were fully closed at day 14 post-wounding. The healed skin from the CNP-miR146a-treated group showed a trend of improved biomechanical properties (increased maximum load and modulus), however it did not reach significance. CONCLUSIONS: We found that a 100-ng dose of CNP-miR146a improved diabetic wound healing and did not impair the biomechanical properties of the skin post-healing. This nanotechnology-based therapy is promising, and future studies are warranted to transfer this therapy to clinical application.

Hand-to-hand coupling and strategies to minimize unintentional energy transfer during laparoscopic surgery.

BACKGROUND: Energy-based devices are used in nearly every laparoscopic operation. Radiofrequency energy can transfer to nearby instruments via antenna and capacitive coupling without direct contact. Previous studies have described inadvertent energy transfer through bundled cords and nonelectrically active wires. The purpose of this study was to describe a new mechanism of stray energy transfer from the monopolar instrument through the operating surgeon to the laparoscopic telescope and propose practical measures to decrease the risk of injury. METHODS: Radiofrequency energy was delivered to a laparoscopic L-hook (monopolar "bovie"), an advanced bipolar device, and an ultrasonic device in a laparoscopic simulator. The tip of a 10-mm telescope was placed adjacent but not touching bovine liver in a standard four-port laparoscopic cholecystectomy setup. Temperature increase was measured as tissue temperature from baseline nearest the tip of the telescope which was never in contact with the energy-based device after a 5-s open-air activation. RESULTS: The monopolar L-hook increased tissue temperature adjacent to the camera/telescope tip by 47 ± 8°C from baseline (P < 0.001). By having an assistant surgeon hold the camera/telescope (rather than one surgeon holding both the active electrode and the camera/telescope), temperature change was reduced to 26 ± 7°C (P < 0.001). Alternative energy devices significantly reduced temperature change in comparison to the monopolar instrument (47 ± 8°C) for both the advanced bipolar (1.2 ± 0.5°C; P < 0.001) and ultrasonic (0.6 ± 0.3°C; P < 0.001) devices. CONCLUSIONS: Stray energy transfers from the monopolar "bovie" instrument through the operating surgeon to standard electrically inactive laparoscopic instruments. Hand-to-hand coupling describes a new form of capacitive coupling where the surgeon's body acts as an electrical conductor to transmit energy. Strategies to reduce stray energy transfer include avoiding the same surgeon holding the active electrode and laparoscopic camera or using alternative energy devices.

Operating Room Fires and Surgical Skin Preparation.

BACKGROUND: Operating room fires are "never events" that remain an under-reported source of devastating complications. One common set-up that promotes fires is the use of surgical skin preparations combined with electrosurgery and oxygen. Limited data exist examining the incidence of fires and surgical skin preparations. STUDY DESIGN: A standardized, ex vivo model was created with a 15 × 15 cm section of clipped porcine skin. An electrosurgical "Bovie" pencil was activated for 2 seconds on 30 Watts coagulation mode in 21% oxygen (room air), both immediately and 3 minutes after skin preparation application. Skin preparations with and without alcohol were tested, and were applied with and without pooling. Alcohol-based skin preparations included 70% isopropyl alcohol (IPA) with 2% chlorhexidine gluconate, 74% IPA with 0.7% iodine povacrylex, and plain 70% IPA. RESULTS: No fires occurred with nonalcohol-based preparations (p < 0.001 vs alcohol-based preparations). Alcohol-based preparations caused flash flames at 0 minutes in 22% (13 of 60) and at 3 minutes in 10% (6 of 60) of tests. When examining pooling of alcohol-based preparations, fires occurred in 38% (23 of 60) at 0 minutes and 27% (16 of 60) at 3 minutes. CONCLUSIONS: Alcohol-based skin preparations fuel operating room fires in common clinical scenarios. Following manufacturer guidelines and allowing 3 minutes for drying, surgical fires were still created in 1 in 10 cases without pooling and more than one-quarter of cases with pooling. Surgeons can decrease the risk of an operating room fire by using nonalcohol-based skin preparations or avoiding pooling of the preparation solution.

Measuring social contacts in the emergency department.

BACKGROUND: Infectious individuals in an emergency department (ED) bring substantial risks of cross infection. Data about the complex social and spatial structure of interpersonal contacts in the ED will aid construction of biologically plausible transmission risk models that can guide cross infection control. METHODS AND FINDINGS: We sought to determine the number and duration of contacts among patients and staff in a large, busy ED. This prospective study was conducted between 1 July 2009 and 30 June 2010. Two 12-hour shifts per week were randomly selected for study. The study was conducted in the ED of an urban hospital. There were 81 shifts in the planned random sample of 104 (78%) with usable contact data, during which there were 9183 patient encounters. Of these, 6062 (66%) were approached to participate, of which 4732 (78%) agreed. Over the course of the year, 88 staff members participated (84%). A radiofrequency identification (RFID) system was installed and the ED divided into 89 distinct zones structured so copresence of two individuals in any zone implied a very high probability of contact <1 meter apart in space. During study observation periods, patients and staff were given RFID tags to wear. Contact events were recorded. These were further broken down with respect to the nature of the contacts, i.e., patient with patient, patient with staff, and staff with staff. 293,171 contact events were recorded, with a median of 22 contact events and 9 contacts with distinct individuals per participant per shift. Staff-staff interactions were more numerous and longer than patient-patient or patient-staff interactions. CONCLUSIONS: We used RFID to quantify contacts between patients and staff in a busy ED. These results are useful for studies of the spread of infections. By understanding contact patterns most important in potential transmission, more effective prevention strategies may be implemented.