Dislodgement of port-A catheters in pediatric oncology patients: 11 years of experience.

BACKGROUND: Port-A catheters are frequently used in pediatric cancer patients. Their dislodgement is potentially seriously risky although the incidence is not high. We analyzed our 11 years of data to address this important problem. METHODS: From January 2001 to December 2011, 330 port-A catheters of different brands were implanted in pediatric cancer patients. In total, eight children suffered a dislodgement of their catheter. Their ages ranged from four to thirteen years, with a median age of ten. Five patients presented with catheter dysfunction, two presented with a cough and one was identified incidentally during surgery to remove his port. RESULTS: The downstream ends of the dislodged catheters were located in the right atrium (three patients), left pulmonary artery (three) and inferior vena cava (two). Six of the eight catheters were broken at the site of anastomosis to the port and the other two were broken halfway in between. All episodes of dislodgement happened after the chemotherapy regimen was completed. The dislodged catheters were successfully retrieved without complications by transcatheter retrieval using a gooseneck snare. CONCLUSIONS: The dislodgment rate of port-A catheter in our series was 2.4%. Chest X-rays can rapidly detect the problem. Most of the catheters were broken at the site of anastomosis. Earlier explantation of port-A catheters after completing chemotherapy may be considered to avoid the dislodgement of catheters, but this needs to be weighed against the possibility of underlying disease recurrence. However, we should re-examine how long port-A catheters need to be retained after chemotherapy considering the improved cure rate of pediatric cancer.

Controlled rupture of magnetic polyelectrolyte microcapsules for drug delivery.

In this study, a magnetic-sensitive microcapsule was prepared using Fe 3O 4/poly(allylamine) (Fe 3O 4/PAH) polyelectrolyte to construct the shell. Structural integrity, microstructural evolution, and corresponding release behaviors of fluorescence dyes and doxorubicin were systematically investigated. Experimental observations showed that the presence of the magnetic nanoparticles in the shell structure allowed the shell structure to evolve from nanocavity development to final rupture of the shell under a given magnetic stimulus of different time durations. Such a microstructural evolution of the magnetic sensitive shell structure explained a corresponding variation of the drug release profile, from relatively slow release to burst-like behavior at different stages of stimulus. It has proposed that the presence of magnetic nanoparticles produced heat, due to magnetic energy dissipation (as Brown and Neel relaxations), and mechanical vibration and motion that induced stress development in the thin shell. Both mechanisms significantly accelerated the relaxation of the shell structure, causing such a microstructural evolution. With such a controllable microstructural evolution of the magnetic-sensitive shell structure, active substances can be well-regulated in a manageable manner with a designable profile according to the time duration under magnetic field. A cell culture study also indicated that the magnetic-sensitive microcapsules allowed a rapid uptake by the A549 cell line, a cancerous cell line, suggesting that the magnetic-sensitive microcapsule with controllable rupturing behavior of the shell offers a potential and effective drug carrier for anticancer applications.