Fluid Flow Analysis of Neonatal Dual-Lumen Cannulas for Venovenous Extracorporeal Membrane Oxygenation.

Hemolysis persists as a common and serious problem for neonatal patients on extracorporeal membrane oxygenation (ECMO). Since the cannula within the ECMO circuit is associated with hemolysis-inducing shear stresses, real-world internal fluid flow measurements are urgently needed to understand the mechanism and confirm computational estimates. This study appears to be the first experimental study of fluid flow inside commercial ECMO dual-lumen cannulas (DLCs) and first particle image velocimetry (PIV) visualization inside a complicated medical device. The internal geometries of four different opaque neonatal DLCs, both atrial and bicaval positioning geometries each sized 13 Fr and 16 Fr, were replicated by three-dimensional printing clear lumen scaled-up models, which were integrated in a circuit with appropriate ECMO flow parameters. PIV was then used to visualize two-dimensional fluid flow in a single cross section within the models. An empirical model accounting for shear stress and exposure time was used to compare the maximum expected level of hemolysis through each model. The maximum measured peak shear stress recorded was 16±2 Pa in the top arterial bicaval 13 Fr model. The atrial and 16 Fr cannula models never produced greater single-pass peak shear stress or hemolysis than the bicaval and 13 Fr models, respectively, and no difference was found in hemolysis at two different flow rates. After 5 days of flow, small DLC-induced hemolysis values for a single pass through each cannula were modeled to linearly accumulate and caused the most severe hemolysis in the bicaval 13 Fr DLC. Engineering and clinical solutions to improve cannula safety are proposed.

Neonatal venoarterial and venovenous ECMO.

ECMO remains an important support tool in the treatment of neonates with reversible congenital cardiopulmonary diseases. There are specific circumstances that call for either venoarterial (VA) or venovenous (VV) ECMO in neonates. While limited by the infant's the size and gestational age, ECMO can confer exceptional survival rates to a number of neonates who can often develop without devastating complications. However, it remains a labor and time intensive endeavor, which may be impractical or unattainable in resource-limited environments. While adult and pediatric ECMO indications and equipment options have expanded in recent years, neonatal ECMO continues to be a niche subspecialty requiring specific expertise and technical skill, especially considering the ever-changing neonatal physiology in the setting of cardiopulmonary support. It is critical to recognize the unique approaches to cannulation options, imaging, vessel management, anticoagulation, and monitoring protocols to achieve optimal outcomes. Thus, it becomes nearly impossible to separate the role of pediatric surgeons from the continuous involvement with and management of neonatal ECMO patients. This necessitates that pediatric surgeons in ECMO centers continue to hone their expertise and remain heavily involved in neonatal ECMO. This section reviews the most critical current approaches and unresolved controversies in neonatal ECMO with special attention to the practical aspects and decisions a surgeon faces in initiation and termination of neonatal ECMO.

Postnatal Myelomeningocele Repair in the United States: Rates and Disparities Before and After the Management of Myelomeningocele Study Trial.

BACKGROUND AND OBJECTIVES: Evolving technologies have influenced the practice of myelomeningocele repair (MMCr), including mandatory folic acid fortification, advances in prenatal diagnosis, and the 2011 Management of Myelomeningocele Study (MOMS) trial demonstrating benefits of fetal over postnatal MMCr in select individuals. Postnatal MMCr continues to be performed, especially for those with limitations in prenatal diagnosis, health care access, anatomy, or personal preference. A comprehensive, updated national perspective on the trajectory of postnatal MMCr volumes and patient disparities is absent. We characterize national trends in postnatal MMCr rates before and after the MOMS trial publication (2000-2010 vs 2011-2019) and examine whether historical disparities persist. METHODS: This retrospective, cross-sectional analysis queried Nationwide Inpatient Sample data for postnatal MMCr admissions. Annual and race/ethnicity-specific rates were calculated using national birth registry data. Time series analysis assessed for trends relative to the year 2011. Patient, admission, and outcome characteristics were compared between pre-MOMS and post-MOMS cohorts. RESULTS: Between 2000 and 2019, 12 426 postnatal MMCr operations were estimated nationwide. After 2011, there was a gradual, incremental decline in the annual rate of postnatal MMCr. Post-MOMS admissions were increasingly associated with Medicaid insurance and the lowest income quartiles, as well as increased risk indices, length of stay, and hospital charges. By 2019, race/ethnicity-adjusted rates seemed to converge. The mortality rate remained low in both eras, and there was a lower rate of same-admission shunting post-MOMS. CONCLUSION: National rates of postnatal MMCr gradually declined in the post-MOMS era. Medicaid and low-income patients comprise an increasing majority of MMCr patients post-MOMS, whereas historical race/ethnicity-specific disparities are improving. Now more than ever, we must address disparities in the care of MMC patients before and after birth.

Survival and Scoliosis Following Resection of Chest Wall Tumors in Children and Adolescents: A Single-center Retrospective Analysis.

OBJECTIVE: We reviewed our experience with pediatric chest wall tumors (CWTs) to identify variables associated with survival, scoliosis development, and need for corrective scoliosis surgery. BACKGROUND: Chest wall neoplasms in children or adolescents are rare. Consequently, there are few large series that detail survival or quality of life indicators, like scoliosis. METHODS: Medical records were reviewed for all chest wall resections for primary and metastatic CWT performed from October 1, 1986 to September 30, 2016 on patients 21 years or younger at diagnosis. Kaplan-Meier distributions were compared using the log-rank test. Variables correlated with survival, scoliosis development, or need for corrective surgeries were analyzed using competing-risk analysis. RESULTS: Seventy-six cases [57 (75%) primary, 19 (25%) metastatic] were identified. Median age at diagnosis was 15.6 years (range: 0.5-21 years). Tumor types were Ewing sarcoma family tumors (54%), other soft tissue sarcomas (21%), osteosarcoma (11%), rhabdomyosarcoma (7%), and other (8%). A median of 3 (range: 1-5) contiguous ribs were resected. Surgical reconstruction included composite Marlex mesh and methyl-methacrylate, Gore-Tex, or primary closure in 57%, 28%, and 14% of procedures, respectively. Overall 5-year survival was 61% (95% confidence interval: 50%-75%). Scoliosis developed in 19 (25%) patients; 6 patients required corrective surgery. Variables associated with overall survival were the presence of metastatic disease at diagnosis, and whether the chest tumor itself was a primary or metastatic lesion. Younger age at chest wall resection was associated with the need for corrective surgery in patients who developed scoliosis. CONCLUSIONS: Among pediatric and adolescent patients with CWTs, survival depends primarily on the presence of metastases. Age, type of chest wall reconstruction, and tumor size are not associated with scoliosis development. Among patients who develop scoliosis, younger patients are more likely to require corrective surgery.

Proximity to the Diaphragm Predicts the Presence of Rhabdomyomatous Dysplasia in Congenital Pulmonary Airway Malformations.

INTRODUCTION: Rhabdomyomatous dysplasia (RD) is a pathologic finding in CPAMs that was incorrectly attributed to their malignant potential. The increasing recognition of extrathoracic (intradiaphragmatic and intraabdominal) congenital pulmonary airway malformations (CPAMs) offers a clue to the origin of RD. We hypothesize that the presence of RD is related to the CPAM's anatomic location. MATERIALS AND METHODS: Retrospective review was performed of all children who underwent resection of a CPAM during a 10-year period. The age at the time of operation, location of the CPAM, and pathologic findings were collected. Peridiaphragmatic location was defined as within the inferior pulmonary ligament, deep to the diaphragmatic portion of the parietal pleura ("intradiaphragmatic") or adjacent to the abdominal side of the diaphragm. Statistical analysis was performed using Fisher's exact test for 2 × 2 tables. RESULTS: Twenty-six patients with CPAM were identified. Preoperative imaging was performed by computed tomography (CT) scan (16/26), ultrasound (5/26), magnetic resonance imaging (MRI) (1/26), and chest radiograph (4/26). The median age at resection was 15 months. Of these, 16 were pure cystic adenomatoid malformations, 4 were extralobar sequestrations, 4 were intralobar sequestrations, and 2 were bronchogenic cysts. Nine lesions were peridiaphragmatic with four being intradiaphragmatic (44%). Eight of the nine resected peridiaphragmatic lesions contained histologic evidence of rhabdomyomatous changes (89%, confidence interval [CI] 52-99%). None of the other lesions contained RD (CI 0-19%, p < 0.001). CONCLUSION: RD was seen exclusively, and in virtually all peridiaphragmatic CPAMs. While the exact significance of RD remains unclear, it may represent incorporation of striated muscle tissue associated with the developing diaphragm.

Centrifugal pumps and hemolysis in pediatric extracorporeal membrane oxygenation (ECMO) patients: An analysis of Extracorporeal Life Support Organization (ELSO) registry data.

PURPOSE: It is currently unclear whether centrifugal pumps cause more hemolysis than roller pumps in extracorporeal membrane oxygenation (ECMO) circuits. The aim of this study was to help answer that question in pediatric patients. METHODS: A limited deidentified data set was extracted from the international multicenter Extracorporeal Life Support Organization (ELSO) registry comprising all reported ECMO runs for patients 18years or younger between 2010 and 2015. Logistic regression was used to evaluate a possible association between hemolysis and pump type, controlling for patient demographics, circuit factors, and complications. RESULTS: 14,776 ECMO runs for 14,026 patients had pump type recorded. Centrifugal pumps were employed in 60.4% of ECMO circuits. Hemolysis was a reported complication for 1272 (14%) centrifugal pump runs and for 291 (5%) roller pump runs. 1755 (20%) centrifugal pump runs reported kidney injury as compared to 797 (14%) roller pump runs. In the full logistic regression, the odds of hemolysis were significantly greater for runs using centrifugal pumps (OR 3.3, 95% CI 2.9-3.8, p<0.001). CONCLUSIONS: In this retrospective analysis of a large international data set, the use of centrifugal pumps was associated with increased rates of hemolysis, hyperbilirubinemia, and kidney injury. TYPE OF STUDY: Retrospective cohort study. LEVEL OF EVIDENCE: Level III.

Routine Use of Distal Arterial Perfusion in Pediatric Femoral Venoarterial Extracorporeal Membrane Oxygenation.

Lower-extremity ischemia is a significant complication in children on femoral venoarterial extracorporeal membrane oxygenation (VA ECMO). Our institution currently routinely uses distal perfusion catheters (DPCs) in all femoral arterial cannulations in attempts to reduce ischemia. We performed a single-center, retrospective review of pediatric patients supported with femoral VA ECMO from January 2005 to November 2015. The outcomes of patients with prophylactic DPC placement at cannulation (prophylactic DPC) were compared to a historical group with DPCs placed in response only to clinically evident ischemic changes (reactive DPC). Ischemic complication requiring invasive intervention (fasciotomy or amputation) was the primary outcome. Twenty-nine patients underwent a total of 31 femoral arterial cannulations, 17 with prophylactic DPC and 14 with reactive DPC. Ischemic complications requiring invasive intervention developed in 2 of 17 (12%) prophylactic DPC patients versus 4 of 14 (29%) reactive DPC. In the reactive DPC group, 7 of 14 (50%) had ischemic changes postcannulation, six underwent DPC placement, and three out of six of these patients still required invasive intervention. One of the seven patients had ischemic changes, did not undergo DPC, and required amputation. While a greater percentage of patients in the prophylactic group was cannulated during extracorporeal cardiopulmonary resuscitation (ECPR), statistical significance was not otherwise demonstrated. We demonstrate feasibility of superficial femoral artery (SFA) access in pediatric patients. We note fewer ischemic complications with prophylactic DPC placement, and observe that salvaging a limb with a reactive DPC was only successful 50% of the time. Although there was no statistical difference in the primary outcome between the two groups, limitations and confounding factors include small sample size and a greater percentage of patients in the prophylactic DPC group cannulated with ECPR in progress.

Aberrant lymphatic endothelial progenitors in lymphatic malformation development.

Lymphatic malformations (LMs) are vascular anomalies thought to arise from dysregulated lymphangiogenesis. These lesions impose a significant burden of disease on affected individuals. LM pathobiology is poorly understood, hindering the development of effective treatments. In the present studies, immunostaining of LM tissues revealed that endothelial cells lining aberrant lymphatic vessels and cells in the surrounding stroma expressed the stem cell marker, CD133, and the lymphatic endothelial protein, podoplanin. Isolated patient-derived CD133+ LM cells expressed stem cell genes (NANOG, Oct4), circulating endothelial cell precursor proteins (CD90, CD146, c-Kit, VEGFR-2), and lymphatic endothelial proteins (podoplanin, VEGFR-3). Consistent with a progenitor cell identity, CD133+ LM cells were multipotent and could be differentiated into fat, bone, smooth muscle, and lymphatic endothelial cells in vitro. CD133+ cells were compared to CD133- cells isolated from LM fluids. CD133- LM cells had lower expression of stem cell genes, but expressed circulating endothelial precursor proteins and high levels of lymphatic endothelial proteins, VE-cadherin, CD31, podoplanin, VEGFR-3 and Prox1. CD133- LM cells were not multipotent, consistent with a differentiated lymphatic endothelial cell phenotype. In a mouse xenograft model, CD133+ LM cells differentiated into lymphatic endothelial cells that formed irregularly dilated lymphatic channels, phenocopying human LMs. In vivo, CD133+ LM cells acquired expression of differentiated lymphatic endothelial cell proteins, podoplanin, LYVE1, Prox1, and VEGFR-3, comparable to expression found in LM patient tissues. Taken together, these data identify a novel LM progenitor cell population that differentiates to form the abnormal lymphatic structures characteristic of these lesions, recapitulating the human LM phenotype. This LM progenitor cell population may contribute to the clinically refractory behavior of LMs.

Extracorporeal membrane oxygenation to support whole-lung lavage in pulmonary alveolar proteinosis: salvage of the drowned lungs.

Pulmonary alveolar proteinosis is a rare lung disease characterized by accumulation of lipoproteinaceous material within the alveoli. Therapeutic whole-lung lavage (WLL) under general anesthesia is the standard treatment in patients with progressive symptomatic disease. Severe hypoxemic respiratory failure is uncommon, yet when present poses a technical challenge to performing WLL without further compromising respiratory status. Rarely, hyperbaric chamber or extracorporeal membrane oxygenation (ECMO) has been utilized to perform WLL to manage severe hypoxemia, with venovenous ECMO being used more often. We present a case of hypoxemic and hypercarbic respiratory failure from pulmonary alveolar proteinosis successfully managed by placing the patient on venoarterial ECMO to facilitate the performance of bilateral WLL.

Outcomes of laparoscopic ventral hernia repair with routine defect closure using "shoelacing" technique.

INTRODUCTION: Laparoscopic approach has become standard for many ventral hernia repairs. The benefits of minimal access include reduced wound complications, faster functional recovery, and improved cosmesis, among others. However, "bridging" of hernia defects during traditional laparoscopic ventral hernia repair (LVHR) often leads to seromas or bulging and, importantly, does not restore a functional abdominal wall. We have modified our approach to LVHR to routinely utilize transabdominal defect closure ("shoelacing" technique) prior to mesh placement. Herein, we aim to analyze outcomes of LVHR with shoelacing. METHODS: Consecutive patients undergoing LVHR with shoelacing were reviewed retrospectively. Main outcome measures included patient demographics, previous surgical history, intraoperative time, mesh type and size, postoperative complications, length of hospitalization, and hernia recurrence. RESULTS: Forty-seven consecutive patients underwent LVHR with defect closure. Average body mass index (BMI) was 32 kg/m2 (range 22-50 kg/m2). Eighteen (38%) patients had an average of 1.5 previous repairs (range 1-3). Mean defect size was 82 cm2 (range 16-300 cm2), requiring a median of 4 (range 2-7) transabdominal stitches for shoelacing. Two patients required endoscopic component separation to facilitate defect closure. Mean mesh size used was 279 cm2 (range 120-600 cm2). Mean operative time was 134 min (range 40-280 min). There were no intraoperative complications. Average length of hospitalization was 2.9 days (range 1-10 days). There were two major postoperative complications [one pulmonary embolism (PE), one stroke]; however, there was no wound-related morbidity or significant seromas. At mean follow-up of 16.2 months, there have been no recurrences. CONCLUSIONS: LVHR with defect closure confers a strong advantage in hernia repair, shifting the paradigm towards more physiologic abdominal wall reconstruction. In this series, we found our approach to be safe and comparable to historic controls. While providing reliable hernia repair, the addition of defect closure in our patients essentially eliminated postoperative seroma. We advocate routine use of the shoelace technique during laparoscopic ventral hernia repair.

Congenital subcostal hernia with unusual contents.

Congenital hernias arising in the subcostal region are rare. We describe a case of a former preterm infant, born with congenitally fused right 11th and 12th ribs and a protuberant mass in the right subcostal region. This mass was associated with a small fascial defect and herniation of abdominal contents. At operation, the mass was determined to be a hernia with an incarcerated ovarian remnant and fallopian tube.