Jeffrey W. Gander

Limb ischemia after common femoral artery cannulation for venoarterial extracorporeal membrane oxygenation: an unresolved problem

PURPOSE Extracorporeal Life Support Organization Registry data confirm that the number of pediatric patients being supported by extracorporeal membrane oxygenation (ECMO) is increasing. To minimize the potential neurologic effects of carotid artery ligation, the common femoral artery (CFA) is frequently being used for arterial cannulation. The cannula has the potential for obstructing flow to the lower limb, thus increasing ischemia and possible limb loss. We present a single institutions experience with CFA cannulation for venoarterial (VA) ECMO and ask whether any precannulation variables correlate with the development of significant limb ischemia. METHODS We reviewed all pediatric patients who were supported by VA ECMO via CFA cannulation from January 2000 to February 2010. Limb ischemia was the primary variable. The ischemia group was defined as the patients requiring an intervention because of the development of lower extremity ischemia. The patients in the no-ischemia group did not develop significant ischemia. Continuous variables were reported as medians with interquartile ranges and compared using Mann-Whitney U tests. Differences in categorical variables were assessed using χ² testing (Fishers Exact). Statistical significance was assumed at P < .05. RESULTS Twenty-one patients (age, 2-22 years) were cannulated via the CFA for VA ECMO. Significant ischemia requiring intervention (ischemia group) occurred in 11 (52%) of 21. In comparing the 2 groups (ischemia vs no ischemia), no clinical variables predicted the development of ischemia (Table 1). In the ischemia group, 9 (81%) of 11 had a distal perfusion catheter (DPC) placed. Complications of DPC placement included one case of compartment syndrome requiring a fasciotomy and one patient requiring interval toe amputation. Of the 2 patients in the ischemia group who did not have a DPC placed, 1 required a vascular reconstruction of an injured superficial femoral artery and 1 underwent a below-the-knee amputation. Mortality was lower in the ischemia group (27% vs 60%). CONCLUSIONS Limb ischemia remains a significant problem, as more than half of our patients developed it. The true incidence may not be known as a 60% mortality in the no-ischemia group could mask subsequent ischemia. Although children are at risk for developing limb ischemia/loss, no variable was predictive of the development of significant limb ischemia in our series. Because of the inability to predict who will develop limb ischemia, early routine placement of a DPC at the time of cannulation may be warranted. However, DPCs do not completely resolve issues around tissue loss and morbidity. Prevention of limb ischemia/loss because of CFA cannulation for VA ECMO continues to be a problem that could benefit from new strategies.

Early recurrence of congenital diaphragmatic hernia is higher after thoracoscopic than open repair: a single institutional study.

INTRODUCTION Experience in thoracoscopic congenital diaphragmatic hernia (CDH) repair has expanded, yet efficacy equal to that of open repair has not been demonstrated. In spite of reports suggesting higher recurrent hernia rates after thoracoscopic repair, this approach has widely been adopted into practice. We report a large, single institutional experience with thoracoscopic CDH repair with special attention to recurrent hernia rates. METHODS We reviewed the records of neonates with unilateral CDH repaired between January 2006 and February 2010 at Morgan Stanley Childrens Hospital. Completely thoracoscopic repairs were compared to open repairs of the same period. In addition, successful thoracoscopic repairs were compared with thoracoscopic repairs that developed recurrence. Data were analyzed by Mann-Whitney U and Fisher exact tests. RESULTS Thirty-five neonates underwent attempted thoracoscopic repair, with 26 completed. Concurrently, 19 initially open CDH repairs were performed. Preoperatively, patients in the open repair group required more ventilatory support than the thoracoscopic group. Recurrence was higher after thoracoscopic repair (23% vs 0%; P = .032). In comparing successful thoracoscopic repairs to those with recurrence, none of the factors analyzed were predictive of recurrence. CONCLUSIONS Early recurrence of hernia is higher in thoracoscopic CDH repairs than in open repairs. Technical factors and a steep learning curve for thoracoscopy may account for the higher recurrence rates, but not patient severity of illness. In an already-tenuous patient population, performing the repair thoracoscopically with a higher risk of recurrence may not be advantageous.

Iatrogenic esophageal perforation in children

Esophageal perforation is most commonly iatrogenic in origin with nasogastric tube insertion, stricture dilation, and endotracheal intubation, being the most frequent sources of the injury in infants and children. Clinical presentation depends on whether the cervical, thoracic, or abdominal esophagus is injured. Any patient complaining of chest pain after an upper endoscopy has esophageal perforation until proven otherwise. In infants and children, plain chest films and esophagography may assist in making the diagnosis. Hemodynamically stable patients with a contained perforation may be managed medically. Free perforation and hemodynamic lability mandates a more aggressive surgical approach for wide drainage of the mediastinum and pleural spaces. Exploration of the chest for attempted direct repair of the injury is now only rarely indicated. Mortality rates have been reported between 20 and 28% with delays in diagnosis and treatment appearing to be most strongly correlated with poor outcomes.

Contrast Ultrasound Imaging for Identification of Early Responder Tumor Models to Anti-Angiogenic Therapy

Agents targeting vascular endothelial growth factor (VEGF) have been validated as cancer therapeutics, yet efficacy can differ widely between tumor types and individual patients. In addition, such agents are costly and can have significant toxicities. Rapid noninvasive determination of response could provide significant benefits. We tested if response to the anti-VEGF antibody bevacizumab (BV) could be detected using contrast-enhanced ultrasound imaging (CEUS). We used two xenograft model systems with previously well-characterized responses to VEGF inhibition, a responder (SK-NEP-1) and a non-responder (NGP), and examined perfusion-related parameters. CEUS demonstrated that BV treatment arrested the increase in blood volume in the SK-NEP-1 tumor group only. Molecular imaging of α(V)β(3) with targeted microbubbles was a more sensitive prognostic indicator of BV efficacy. CEUS using RGD-labeled microbubbles showed a robust decrease in α(V)β(3) vasculature following BV treatment in SK-NEP-1 tumors. Paralleling these findings, lectin perfusion assays detected a disproportionate pruning of smaller, branch vessels. Therefore, we conclude that the response to BV can be identified soon after initiation of treatment, often within 3 days, by use of CEUS molecular imaging techniques. The use of a noninvasive ultrasound approach may allow for earlier and more effective determination of efficacy of antiangiogenic therapy.

Monitoring early tumor response to drug therapy with diffuse optical tomography

Although anti-angiogenic agents have shown promise as cancer therapeutics, their efficacy varies between tumor types and individual patients. Providing patient-specific metrics through rapid noninvasive imaging can help tailor drug treatment by optimizing dosages, timing of drug cycles, and duration of therapy-thereby reducing toxicity and cost and improving patient outcome. Diffuse optical tomography (DOT) is a noninvasive three-dimensional imaging modality that has been shown to capture physiologic changes in tumors through visualization of oxygenated, deoxygenated, and total hemoglobin concentrations, using non-ionizing radiation with near-infrared light. We employed a small animal model to ascertain if tumor response to bevacizumab (BV), an anti-angiogenic agent that targets vascular endothelial growth factor (VEGF), could be detected at early time points using DOT. We detected a significant decrease in total hemoglobin levels as soon as one day after BV treatment in responder xenograft tumors (SK-NEP-1), but not in SK-NEP-1 control tumors or in non-responder control or BV-treated NGP tumors. These results are confirmed by magnetic resonance imaging T2 relaxometry and lectin perfusion studies. Noninvasive DOT imaging may allow for earlier and more effective control of anti-angiogenic therapy.

Laparoscopic Excision of Choledochal Cysts with Total Intracorporeal Reconstruction

PURPOSE There are numerous published reports of laparoscopic resection of choledochal cysts (CDCs), but almost all involve extracorporeal reconstruction of a biliary drainage system. We describe and evaluate the technique of laparoscopic CDC resection with total intracorporeal reconstruction. METHODS We reviewed all patients who underwent a laparoscopic CDC resection from March 2005 to January 2010 at Rocky Mountain Childrens Hospital and Childrens Hospital of New York-Presbyterian. We obtained data on operative time, characteristics of reconstruction, time to initiation of diet, length of stay, complications, and outcome. RESULTS Thirteen patients (median age 5 years, range 1-16) underwent a laparoscopic CDC excision with total intracorporeal reconstruction. Four ports were used in all cases and no patients required conversion to an open procedure. Operative time ranged from 130 to 325 minutes (median 240 minutes). Median time to initiation of diet was 1 day (range 1-4 days). Median length of stay was 5 days (range 4-8 days). There were no cases of cholangitis; however, 1 patient developed a small bowel obstruction requiring re-operation. CONCLUSION Laparoscopic resection of CDCs with total intracorporeal reconstruction is a safe and effective technique. The minimal handling of the bowel appears to minimize postoperative ileus, allows for early postoperative feeding and discharge.

Hepatic pulmonary fusion in an infant with a right-sided congenital diaphragmatic hernia and contralateral mediastinal shift.

Hepatic pulmonary fusion is extremely rare with only 9 previous cases reported in the literature. In typical cases, the clinician should be alerted to the possibility of hepatic pulmonary fusion if the chest radiograph shows a large opacity on the right side without a contralateral mediastinal shift. The authors present a case of right-sided diaphragmatic hernia and hepatic pulmonary fusion with associated contralateral mediastinal shift discovered beyond the neonatal period. The 9 previous cases were retrospectively reviewed with special attention to mediastinal shift on preoperative chest radiograph, operative procedure, and mortality. Only one previous case demonstrated a contralateral mediastinal shift. The most common procedure performed was partial separation of the hepatic pulmonary fusion and approximation of the diaphragmatic defect. Four of the previous 9 patients died. In our case, reduction of bowel and approximation of the diaphragmatic defect around the fused liver and lung have been successful.

Fulminant pH1N1-09 influenza-associated myocarditis in pediatric patients.

Objective: To report an atypical presentation of pH1N1-09 influenza infection in children as fulminant myocarditis and tamponade and the successful treatment with extracorporeal membrane oxygenation. Design: Case report. Setting: Pediatric cardiac intensive care unit in a quarternary care childrens hospital. Patients: Two girls, 5 and 7 yrs of age, infected with pH1N1-09 influenza virus who presented in cardiogenic shock with a pericardial effusion and echocardiographic evidence of tamponade from fulminant myocarditis. Interventions: Both patients received a pericardiocentesis. One was managed with multiple, high-dose inotropic agents, whereas the other required institution of extracorporeal membrane oxygenation. Measurements and Main Results: Acute respiratory distress syndrome is the major reported clinical manifestation of pH1N1-09 influenza virus infection in hospitalized pediatric patients. In this report we describe two children with confirmed pH1N1-09 influenza infection that required intensive care for fulminant myocarditis. Neither patient had the typical symptoms of influenza-like illness, respiratory compromise, or evidence of pulmonary involvement. One child required extracorporeal membrane oxygenation. Both children survived to hospital discharge. Conclusions: pH1N1-09 influenza infection can cause fulminant myocarditis in the healthy pediatric population. The clinical presentation may be nonspecific, and the lack of pulmonary symptoms may make diagnosis difficult. Extracorporeal membrane oxygenation support may offer an effective bridge to the recovery of heart function.

The use of recombinant tissue-type plasminogen activator in a newborn with an intracardiac thrombus developed during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) support is often used to support infants and children with hemodynamic or respiratory failure. One of the major obstacles of safely treating a child with ECMO is balancing the risk of hemorrhage with the potential for thrombus development. Managing thrombosis in the setting of ECMO is challenging and has no defined algorithm. The use of recombinant tissue-type plasminogen activator (tPA) for thrombolysis has been previously described in cases where thrombi have developed despite adequate anticoagulation. In such situations, the risk of hemorrhage must be carefully balanced with the benefit of dissolving the clot and reestablishing flow. We present a case of an infant who required ECMO because of severe primary pulmonary hypertension and subsequently developed a right atrial thrombus adjacent to the ECMO cannula. The patient was treated with tPA with immediate improvement but had fatal intracranial hemorrhage almost 3 days after the tPA was administered. In this report, we review the current literature on tPA use during ECMO support and suggest a rational approach.

Inhibition of cyclo-oxygenase 2 reduces tumor metastasis and inflammatory signaling during blockade of vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) blockade is an effective therapy for human cancer, yet virtually all neoplasms resume primary tumor growth or metastasize during therapy. Mechanisms of progression have been proposed to include genes that control vascular remodeling and are elicited by hypoperfusion, such as the inducible enzyme cyclooxygenase-2 (COX-2). We have previously shown that COX-2 inhibition by the celecoxib analog SC236 attenuates perivascular stromal cell recruitment and tumor growth. We therefore examined the effect of combined SC236 and VEGF blockade, using the metastasizing orthotopic SKNEP1 model of pediatric cancer. Combined treatment perturbed tumor vessel remodeling and macrophage recruitment, but did not further limit primary tumor growth as compared to VEGF blockade alone. However, combining SC236 and VEGF inhibition significantly reduced the incidence of lung metastasis, suggesting a distinct effect on prometastatic mechanisms. We found that SC236 limited tumor cell viability and migration in vitro, with effects enhanced by hypoxia, but did not change tumor proliferation or matrix metalloproteinase expression in vivo. Gene set expression analysis (GSEA) indicated that the addition of SC236 to VEGF inhibition significantly reduced expression of gene sets linked to macrophage mobilization. Perivascular recruitment of macrophages induced by VEGF blockade was disrupted in tumors treated with combined VEGF- and COX-2-inhibition. Collectively, these findings suggest that during VEGF blockade COX-2 may restrict metastasis by limiting both prometastatic behaviors in individual tumor cells and mobilization of macrophages to the tumor vasculature.