RESUMEN
Tests are ongoing to conduct ~20 MA z-pinch implosions on the Z accelerator at Sandia National Laboratory using Ar, Kr, and D2 gas puffs as the imploding loads. The relatively high cost of operations on a machine of this scale imposes stringent requirements on the functionality, reliability, and safety of gas puff hardware. Here we describe the development of a prototype gas puff system including the multiple-shell nozzles, electromagnetic drivers for each nozzle's valve, a UV pre-ionizer, and an inductive isolator to isolate the ~2.4 MV machine voltage pulse present at the gas load from the necessary electrical and fluid connections made to the puff system from outside the Z vacuum chamber. This paper shows how the assembly couples to the overall Z system and presents data taken to validate the functionality of the overall system.
RESUMEN
BACKGROUND: Accidental placement of a large sheath or catheter in an artery during central venous cannulation, though rare, is a potentially devastating complication. The present study reviews our 14-year experience with this complication to determine appropriate role of surgical management. STUDY DESIGN: Review was conducted of all cases involving patients treated by the vascular surgery service from July 1989 to June 2003 for accidental placement of a large-caliber cannula (>or= 7 F) in an artery during catheterization of the jugular vein. Two management techniques were used during this period: removal of cannula followed by application of local pressure; and surgical exploration, removal of cannula under direct vision, and repair of artery. RESULTS: Eleven patients (5 men, 6 women) aged 35 to 73 years (mean age 56 years) were treated for cannulas placed accidentally in an artery. In nine patients, the cannula entered the carotid artery, and in two patients it entered the subclavian artery. Three patients had undergone placement of 8.5-F sheaths for monitoring cardiac hemodynamics, and 8 patients had triple-lumen catheters for fluid infusion or parenteral nutrition. Eight patients (three sheath, five catheter) were asymptomatic at the time of cannula removal. In three patients, the correct diagnosis was missed initially and infusion was started. All three developed neurologic symptoms. In two patients, the cannula (sheath) was pulled and pressure applied. One of them developed a stroke and the other developed a pseudoaneurysm that was treated surgically. Nine patients in whom the sheath or catheter was removed by surgical exploration had no new complications related to surgery. CONCLUSIONS: Surgical management seems to be the most effective and safe treatment of arterial misplacement of cannulas during jugular vein catheterization. Further study is needed to determine the optimum management of this potentially devastating complication.