Evaluation of aortopexy in the management of severe tracheomalacia after esophageal atresia repair

Severe tracheomalacia (TM) is a difficult problem in esophageal atresia (EA) patients. We reviewed our experience with aortopexy and other interventions for severe TM in this population. With review ethics board approval, a retrospective review of TM in postoperative EA patients was conducted (1989-2010). Demographics, perinatal, and surgical information regarding EA repair was collected. TM infants were analyzed for symptomatology, clinical severity, investigations, interventions, and outcomes. Data are presented as proportions or median(range). One hundred and thirty-two EA patients were reviewed. Most had type C atresia (87.3%), and 18 patients (13.6%) died. Twenty-five patients (18.9%) had TM of whom five (20%) died. Median symptom onset was 18 days (0-729) after EA repair, with stridor (64%) or retractions/distress (44%) being most frequent. Four and two patients had airway obstruction or cardiorespiratory arrest, respectively. Median time from symptom onset to investigations was 11 days; these were most commonly rigid bronchoscopy (56%) and fluoroscopy (36%). Ten patients (40%) had severe TM on bronchoscopy. Six underwent aortopexy, one fundoplication, and three were treated medically. Length of hospital stay (LOS) post-aortopexy was 13 days (5-60), and ventilation time was 2 days (0-9). LOS was 60.5 (1-69) days postdiagnosis in non-aortopexy patients. Readmission rates for respiratory issues were significantly less in the aortopexy (median 0 vs. 5; P = 0.048) group over 2-year follow up after discharge. Complications of aortopexy included transfusion (1) and temporary diaphragmatic paresis (1), and one mortality secondary to severe congenital cardiac anomalies. Our experience suggests that aortopexy is safe and effective for the treatment of severe TM. It is associated with reduced LOS compared with other treatment strategies and few complications or long-term sequelae.

Pericardial Hemangioma Presenting as Thoracic Mass in utero

Pericardial hemangiomas are rare lesions. We present the case of an infant who was referred to our fetal diagnosis and treatment group for the presence of a left thoracic mass, pleural effusion, and mediastinal shift on fetal ultrasound. The characteristics of the lesion suggested the presence of a pulmonary sequestration. A chest radiograph done at birth was normal. At 2 weeks of age, an enhancing lesion of the left pericardium was identified on chest CT. A cardiac MRI demonstrated enhancement of the mass on T2-weighted images. The patient underwent thoracoscopic assessment of the mass for diagnostic purposes. Multiple lesions were identified along the left pericardium and diaphragm. A frozen section biopsy revealed a hemangioma. The natural history for hemangiomas is gradual regression; however, they may increase acutely in size and cause symptoms prior to involution. Investigations should be performed to identify the involvement of other organs. This case illustrates the need to closely follow all patients with prenatally diagnosed thoracic masses with CT imaging, even when they are asymptomatic and have a normal chest radiograph at birth.

Gastrointestinal duplications

BACKGROUND/PURPOSE

The aim of this study was to review the presentations of gastrointestinal duplication (GID) and to assess the influence of prenatal diagnosis on treatment.

METHODS

Retrospective review of all GID at 2 pediatric hospitals from 1980-2002 was conducted.

RESULTS

Seventy-three patients (M43:F30) were identified: 21 neonates, 28 infants (1 to 24 months), 15 children (1 to 10 years), 9 adolescents (>/=11 years). GID location by frequency was ileum (31.5%), ileocaecal valve (30.2%), duodenum (9.6%), stomach (8.2%), jejunum (8.2%), colon (6.8%), and rectum (5.5%). In neonates and infants, vomiting and distension were the most common presentations. Volvulus, caused by a duplication, occurred in 23.8% of neonates and caused the death of one neonate. Intussusception was identified in 10.9% of patients. In older children and adolescents, pain and vomiting were the most common associations. Six of these patients were being treated for Crohn's disease, with the diagnosis of duplication made at laparotomy. Eighteen patients had a prenatal diagnosis by ultrasound scan, with 77.2% of these asymptomatic after birth. Most prenatal diagnoses occurred after 1991 (77.8%). When comparing an earlier period (1980 to 1991; 29 patients) with the current (1992 to 2002; 44 patients), a greater proportion of the latter patients were asymptomatic (36.4 v 13.8%) and had a lower incidence of complications (volvulus/intussusception).

CONCLUSIONS

GID can lead to life-threatening complications. Prenatal diagnosis should lead to expeditious postnatal investigation and treatment before the onset of symptoms or complications. GID in older children can mimic Crohn's disease. Laparoscopy/laparotomy should be considered in patients with atypical Crohn's disease or when the diagnosis of an intraabdominal mass is unclear.

Evaluation of exogenous surfactant in HCL-induced lung injury

The efficacy of exogenous surfactant administration is influenced by numerous factors, which has resulted in variable outcomes of clinical trials evaluating this treatment for the acute respiratory distress syndrome (ARDS). We investigated several of these factors in an animal model of acid aspiration including different surfactant preparations, and different delivery methods. In addition, high-frequency oscillation (HFO), a mode of mechanical ventilation known to recruit severely damaged lungs, was utilized. Lung injury was induced in adult rabbits via intratracheal instillation of 0.2 N HCl followed by conventional mechanical ventilation (CMV) until Pa(O2)/FI(O2) values ranged from 220 to 270 mm Hg. Subsequently, animals were given one of three surfactants administered via three different methods and physiological responses were assessed over a 1-h period. Regardless of the surfactant treatment strategy utilized, oxygenation responses were not sustained. In contrast, HFO resulted in a superior response compared with all surfactant treatment strategies involving CMV. The deterioration in physiological parameters after surfactant treatment was likely due to overwhelming protein inhibition of the surfactant. In conclusion, various surfactant treatment strategies were not effective in this model of lung injury, although the lungs of these animals were recruitable with HFO, as reflected by the acute and sustained oxygenation improvements.

Alveolar environment influences the metabolic and biophysical properties of exogenous surfactants

Several factors have been shown to influence the efficacy of exogenous surfactant therapy in the acute respiratory distress syndrome. We investigated the effects of four different alveolar environments (control, saline-lavaged, N-nitroso-N-methylurethane, and hydrochloric acid) on the metabolic and functional properties of two exogenous surfactant preparations: bovine lipid extract surfactant and recombinant surfactant-associated protein (SP) C drug product (rSPC) administered to each of these groups. The main difference between these preparations was the lack of SP-B in the rSPC. Our results demonstrated differences in the large aggregate pool sizes recovered from each of the experimental groups. We also observed differences in SP-A content, surface area cycling characteristics, and biophysical activities of these large aggregate forms after the administration of the two exogenous surfactant preparations. We conclude that the alveolar environment plays a critical role, influencing the overall efficacy of exogenous surfactant therapy. Thus further preclinical studies are warranted to investigate the specific factors within the alveolar environment that lead to the differences observed in this study.

Effects of calcium channel blockers on the kinetics of voltage-dependent changes in synaptosomal calcium concentrations

Synaptosomal preparations from rat cerebral cortex have been used in stopped-flow fluorescence studies to measure rapid changes in intrasynaptosomal calcium concentrations upon depolarization. Synaptosomes were loaded with the fluorescent calcium chelating dye, Fura-2, by incubation with the membrane permeant acetoxymethyl ester derivative. Depolarization by elevated external K+ concentration resulted in a rapid increase in cytoplasmic Ca2+ as measured by a quench in Fura-2 fluorescence when excited at 390 nm. The fluorescence change could be reasonably fit by a single exponential process with an apparent rate of 10-15 s-1 and the magnitude of the response was voltage-dependent, increasing with increasing external K+ over the range of 5-30 mM. The observed quench was blocked by micromolar concentrations of the inorganic calcium channel blockers, Cd2+, Co2+ and La3+. Nimodipine, a dihydropyridine which blocks L-type calcium channels, inhibited only 10-15% of the flux response while nitrendipine had no consistent effect. omega-Conotoxin GVIA, a blocker of N-type channels in many species, had only a small inhibitory effect at high (1-10 microM) concentrations. The response was, however, inhibited by pre-incubation of the synaptosomes with venom of the funnel web spider. Agelenopsis aperta (0.1-300 micrograms/ml). Inhibition was observed with both a purified polyamine fraction (FTX) from the venom (IC50 = 4 nl/ml) and a purified peptide toxin, omega-AgaIVA (IC50 = 30 nM). These results indicate that voltage-dependent Ca2+ uptake by mammalian nerve terminals is mediated primarily by channels that are insensitive to dihydropyridines and omega-conotoxin GVIA but are sensitive to components of funnel web spider venom.