NASTRAN modeling and analysis of rigid and flexible walled acoustic cavities

The acoustic slot elements, CSLOTi, are applied to analyze two-dimensional enclosures with fixed or moving boundaries. The capability utilized to compute (a) the acoustic natural modes and frequencies of a rigid walled enclosure and (b) the sound pressure at any point inside an enclosure when the surrounding walls are forced to vibrate. Applications to an automobile passenger compartment illustrate the technique. The axisymmetric fluid elements, CFLUIDi, are used in conjunction with a suitable choice of symmetry planes and a model of the surrounding structure to approximate a two-dimensional enclosure with flexible walls. The enclosure walls are modeled using finite elements or structural modes. Illustrative examples include a comparison of rectangular cavity modes with those calculated using the acoustic slot element and the free vibration modes of two enclosures coupled through a flexible rectangular panel

Laparoscopic Transperitoneal Pyeloplasty

Laparoscopic pyeloplasty is a first-line option for the management of ureteropelvic junction obstruction. It has a greater success rate than endopyelotomy and is associated with a shorter and less intense convalescence than open surgical pyeloplasty. The technique is well established and reproducible, although the procedure is more difficult in certain situations, such as after a previous pyeloplasty. Because laparoscopic suturing is needed, it is considered an advanced laparoscopic procedure. Suturing devices can facilitate suturing, but they are not optimal for all repairs. This article and the accompanying video summarize the preoperative, intraoperative, and postoperative considerations for laparoscopic pyeloplasty.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90443/1/end-2E2010-2E0605.pd

55 Local anaesthetic reduces postoperative analgesic requirements in laparoscopic urological surgery

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75011/1/j.1464-410X.2006.06085_55.x.pd

Convenient Creation and Use of Suturing Supplies for Laparoscopic Partial Nephrectomy

Abstract The closure of the renal defect is the most challenging part of laparoscopic partial nephrectomy when suturing is required. The author presents a method of creating and using suturing material for laparoscopic partial nephrectomy that has been developed over several hundred cases at the author's institution. These techniques can be used to simplify the task of suturing during laparoscopic partial nephrectomy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78109/1/end.2009.0006.pd

The Alternative to Laparoendoscopic Single-Site Surgery: Small Strategic Laparoscopic Incision Placement (SLIP) Nephrectomy Improves Cosmesis Without Technical Restrictions

Background: The latest attempt to improve the cosmesis of laparoscopic surgery is laparoendoscopic single-site surgery (LESS). We present our initial experience with an alternative procedure with similar cosmetic benefit but without technical limitations. Methods: Small strategic laparoscopic incision placement (SLIP) nephrectomy is performed transperitoneally, generally using three 5-mm ports (one in the umbilicus) and one 12-mm port placed below the pubic hairline, such that only two 5-mm scars are visible without close inspection. We assessed our first 21 procedures, which included all but five of the standard transperitoneal nephrectomies by a single surgeon from June 2008 through July 2009. These were matched 1:2 (exactly by gender and American Society of Anesthesiology score, and then closest in age and body mass index) from 96 patients undergoing similar standard transperitoneal laparoscopic procedures from 2005 through 2008. Results: The SLIP and control groups were well matched, with mean age and body mass index differing by only 3.6 years and 1.1, respectively. Of the SLIP patients, 34% were obese or morbidly obese, and a trainee was the primary surgeon in 81% of cases. Mean operative time was 23 minutes longer in the SLIP cases. There was no difference between groups in estimated blood loss, complication rate, or convalescence. Conclusions: Like LESS, SLIP nephrectomy provides improved cosmesis. Unlike LESS, it is only slightly more difficult to perform than standard laparoscopic nephrectomy and can be performed in technically challenging cases (obesity, large specimen, etc). Similar to the literature on LESS, there is no convalescence benefit to SLIP nephrectomy; the advantage over standard laparoscopy is purely cosmetic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90438/1/end-2E2010-2E0340.pd

Single-Setting Bilateral Hand-Assisted Laparoscopic Partial Nephrectomy

Abstract Purpose: To assess the feasibility and safety of single-setting bilateral hand-assisted laparoscopic partial nephrectomy. Materials and Methods: Between August 2003 and June 2004, we performed single-setting bilateral laparoscopic partial nephrectomies on three patients. A hand-assisted approach was used, employing the same hand-assistance incision for both sides. Renal hilar clamping was not required, as the depth of penetration of all six tumors was only 0 to 4mm (mean, 1.8mm). The tumor diameters ranged from 1.8 to 3.8cm (mean, 2.4cm). Results: All operations were performed successfully, with no conversion to open surgery. Excision was performed with bipolar forceps, and final hemostasis was obtained with an argon beam coagulator (Valleylab, Boulder, CO) and Floseal (Baxter, Deerfield, IL), without suturing. The mean estimated blood loss was 208mL. The mean operative time was 246 minutes, which included repositioning. There were no intraoperative complications, and the postoperative course was uneventful in all patients except for a hospital stay of 5 days in one patient owing to transient ileus. Pathology revealed a benign lesion on one side and renal cell carcinoma on the other side in two patients, and bilateral leiomyomas in one patient. All margins of resection were negative, and neither of the two patients with cancer has had recurrence at a mean follow-up of 51 months. Among all three patients, the mean preoperative serum creatinine was 0.9mg/dL, and the average level at a mean of 35 months postoperatively was 1.0mg/dL. Conclusion: Single-setting bilateral hand-assisted laparoscopic partial nephrectomies can be safely and effectively performed on patients with bilateral small exophytic kidney tumors. We do not recommend this technique if both kidneys require temporary hilar occlusion, but it can be considered if only one kidney requires hilar occlusion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78122/1/end.2008.0549.pd

Failure of Percutaneous Endoscopic Resection of a Renal Cystic Nephroma on Longer-Term Follow-Up

In 2005 we reported in this journal the treatment of cystic nephroma, a rare but presumed benign renal tumor, with percutaneous resection. Initial follow-up confirmed removal of the intra-pelvic portion of the cystic nephroma and persistence of the unresected intra-parenchymal portion. Surveillance with computed tomography revealed gradual regrowth of the mass, ultimately resulting in a size greater than that at the time of initial resection. Laparoscopic radical nephrectomy without adrenalectomy revealed benign cystic nephroma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63237/1/end.2007.0441.pd

Tethered body problems and relative motion orbit determination

Selected problems dealing with orbiting tethered body systems have been studied. In addition, a relative motion orbit determination program was developed. Results from these tasks are described and discussed. The expected tethered body motions were examined, analytically, to ascertain what influence would be played by the physical parameters of the tether, the gravity gradient and orbit eccentricity. After separating the motion modes these influences were determined; and, subsequently, the effects of oscillations and/or rotations, on tether force, were described. A study was undertaken, by examining tether motions, to see what type of control actions would be needed to accurately place a mass particle at a prescribed position relative to a main vehicle. Other applications for tethers were studied. Principally these were concerned with the producing of low-level gee forces by means of stabilized tether configurations; and, the initiation of free transfer trajectories from tether supported vehicle relative positions

Ex-Vivo Ureteroscopy at the Time of Live Donor Nephrectomy

Background and Purpose: Potential transplant renal allograft recipients exceed the number of donors. Our institution now considers patients with small, unilateral, nonobstructing, incidental renal calculi for possible renal donation. We adopted ex-vivo ureteroscopy (ExURS) to render these kidneys stone free at the time of renal transplantation. We examined the safety and efficacy of ExURS. Patients and Methods: After confirming a lack of significant metabolic defects on 24-hour urinalysis, 23 patients with small nonobstructing unilateral nephrolithiasis detected on preoperative CT angiography underwent donor nephrectomy. Immediately after cold perfusion, ExURS was performed with ice cold saline irrigation. Retrospective review was performed. Results: Pyeloscopy was successfully performed in all 23 patients. A total of 28 calculi, mean largest diameter 3.9-mm (range 3-6-mm), were visualized in 19 kidneys. Basket extraction and holmium laser lithotripsy was performed in 12 and 6 kidneys, respectively. Treatment rendered 17/19 stone-containing kidneys stone free with a mean treatment time of 6.2 minutes (3-10-min). There were no intraoperative complications. Median serum creatinine level of recipients at 1 month and 1 year were 1.4+/-1.8-mg/dL and 1.3+/-0.6-mg/dL, respectively. At a median follow-up of 63+/-47.2 months, there were no transplant urinary calculi among the recipients. Conclusions: ExURS safely renders live donor kidney allografts stone free with low risk of recurrence. When used appropriately, ExURS could safely increase the number of potential kidney donors and minimize the risk of adverse stone events.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90444/1/end-2E2010-2E0627.pd