Physiologic effect of nifedipine and tamsulosin on contractility of distal ureter.

BACKGROUND AND PURPOSE: Renal colic not only leads to significant morbidity but imposes a financial burden on society in lost productivity and healthcare dollars spent. Both tamsulosin and nifedipine can facilitate spontaneous stone passage in the distal ureter and reduce the associated colic. We evaluated the physiologic effect of these agents on the distal pig ureter. MATERIALS AND METHODS: Bilateral ureters were removed en bloc with the bladder trigone from three pigs. Five-millimeter rings were taken from the intramural and distal ureter. Isometric tension recording was performed during both spontaneous and electrically stimulated contraction. Measurements of contractile interval and amplitude were taken in baseline buffer solution, nifedipine at 10(-6) g/L, and tamsulosin at 10(-6) g/L. Spontaneous contractile activity was also measured with phenylephrine at 10(-4) g/L followed by tamsulosin at 10(-6) g/L. RESULTS: Under conditions of spontaneous contractility, phenylephrine decreased the contraction interval by 46%, an effect which was reversed by tamsulosin. Tamsulosin increased the baseline interval by 27% (P < 0.025) and decreased the amplitude by 7% (P > 0.1). Nifedipine blocked all contractile activity. Under stimulated contractility, tamsulosin had no effect on the interval and decreased the amplitude by 7% (P > 0.1). Nifedipine blocked all contractile activity. CONCLUSIONS: We believe that both tamsulosin and nifedipine prevent the disorganized antiperistalsis associated with ureteral spasm while allowing some degree of antegrade fluid-bolus (stone) propagation. It is this mechanism of action that facilitates spontaneous passage and reduces associated renal colic when tamsulosin and nifedipine are used for the management of ureteral stone disease.

Hand-assisted laparoscopic approach to multiple-organ removal.

BACKGROUND: Over the past decade, laparoscopy has matured to a common, and in some cases, standard surgical approach. Over this time period, many technological advances have contributed to this progression, one of which is hand assistance. Hand-assisted laparoscopy allows a shortened technical learning curve, security and ease in dissection, the ability to remove organs en bloc, and shorter operative times while maintaining the postoperative advantages of laparoscopy. PATIENTS AND METHODS: We present our experience with a hand-assisted laparoscopic approach for two patients requiring bilateral nephrectomy in preparation for renal transplantation and a third patient having concurrent right simple nephrectomy and simple cystectomy for chronic pyocystis. RESULTS: The hand-assisted approach allowed for utilization of one anesthetic, repositioning of the patient without violating the sterile field, and a short convalescent time. The average hospital stay was 5 days, including two patients who required postoperative revascularization of their clotted arteriovenous fistulas. CONCLUSION: The established indications for hand-assisted laparoscopy include removal of large surgical specimens en bloc, anticipated difficult dissection, and failure of standard laparoscopic procedure progression. We propose that removal of multiple organs should be added to this list.

Laser Glare in the Cockpit: Psychophysical Estimates versus Model Predictions of Veiling Luminance Distribution.

Two methods for estimating the visual effects of light scattered from a laser glare source were compared: (1) a veiling luminance (VL) model that convolves a radiometric scan of the corneal light distribution with a point-spread function to calculate the retinal distribution and (2) psychophysically determined equivalent background luminance (EBL). For six subjects, detection thresholds for a 12-arc-min-diameter test spot were measured at 24 points in the glare field (4 quadrants x 6 eccentricities between 0.25 and 8 deg). Measured Weber fractions were used to calculate EBL's for each test point. Output of the VL model matched the EBL data well, but underestimated the EBL at the smallest (0.25-deg) eccentricity and overestimated it at eccentricities from 1 to 4 deg. This model can be a useful predictor of visual decrements in a variety of glare situations.

Laparoscopic surgeries for the bladder.

Various reparative, reconstructive, extirpative, and miscellaneous surgeries of the bladder with laparoscopic techniques are in the process of evolution. Our increasing expertise enhanced by improved instrumentation make these procedures feasible and encourage us to venture into this relatively less explored arena of laparoscopic urology.

Comparative financial analysis of laparoscopic pelvic lymph node dissection performed in 1990-1992 v 1993-1994.

In 1994, it was reported that laparoscopic pelvic lymph node dissection (L-PLND) was US $1350 more expensive than open pelvic lymph node dissection (O-PLND) for the staging of prostate cancer. Despite the lower postoperative expenses associated with L-PLND, the intraoperative expenditures were 52% higher, primarily because of the prolonged operating time and the cost of disposable instrumentation. The objective of the present study was to determine if, with increasing laparoscopic experience and a more competitive surgical supply market, the intraoperative as well as the overall hospital expenses would diminish. The study population consisted of 105 men who underwent staging L-PLND for cancer of the prostate. Group I was composed of 50 patients who underwent surgery between 1990 and 1992, and Group II consisted of 55 patients operated on in 1993 and 1994. All hospital-related expenses were reorganized into preoperative, intraoperative, and postoperative and subsequently corrected for inflationary changes to a base year of 1993-1994. The total overall expenses of the two groups were similar, differing by only $65. Despite a lowering of preoperative and postoperative expenses in the 1993-1994 group by 112% and 31%, respectively, the intraoperative expenses were still $571 higher. The operative time decreased by 19 minutes in the contemporary group, but the expense of surgical supplies continued to increase up to $910 (104%) more than the 1990-1992 group. It is hoped that the use of "laparoscopic kits" as well hospital equipment consortiums will help slow the escalating costs of surgical care. However, it is the responsibility of the laparoscopic surgeon to demonstrate that these procedures are as safe, efficient, and cost-effective as their open counterpart.

Laparoscopic urologic surgery. The financial realities.

Since 1990, laparoscopic surgery has gained an important role in the specialty of urology. This article provides a financial analysis of the three most common urolaparoscopic procedures compared with their open surgical counterpart. The intraoperative costs of laparoscopic surgery are more expensive, but the postoperative expenses are less compared with open surgery. The financial ramifications of a shorter period of convalescence following laparoscopic surgery must be considered.

Comparative financial analysis of laparoscopic versus open pelvic lymph node dissection for men with cancer of the prostate.

Laparoscopic pelvic lymph node dissection has been applied as a minimally invasive staging technique for men with prostate cancer. This procedure has been shown to shorten markedly postoperative hospitalization, decrease analgesic requirements and shorten convalescence period compared to open pelvic node dissection. However, the laparoscopic procedure takes longer to perform and many disposable instruments are used, thus increasing the cost. We determine the overall cost of laparoscopic versus open pelvic lymph node dissection. Between January 1989 and April 1992, 61 men underwent only staging pelvic lymph node dissection for cancer of the prostate at a single university teaching hospital. Of these patients 11 and 50 underwent open and laparoscopic pelvic lymph node dissection, respectively. Information from the hospital business office was reorganized into preoperative, intraoperative and postoperative expenses. All individual charges were transformed up or down to the dollar amounts of the 1990 to 1991 fiscal year so as to correct for inflationary changes. Preoperative costs were not significantly different between the 2 operative approaches. Intraoperative expenses were 52% greater if laparoscopic pelvic lymph node dissection was performed and can be explained by the longer operative times and use of disposable instrumentation. However, the postoperative period lasted an average of 1.61 days following laparoscopic pelvic lymph node dissection. Postoperative nursing and analgesic requirements were significantly more for patients undergoing open pelvic lymph node dissection. The overall postoperative costs following open pelvic lymph node dissection were 280% more expensive than for the laparoscopic procedure. The overall total costs were approximately $1,250 more for laparoscopic pelvic lymph node dissection. Wages lost or earned during this period and rapid return to normal activity following laparoscopic pelvic lymph node dissection would, in our opinion, justify this additional cost.

Treatment of exophthalmos.

Current procedures for Graves' exophthalmos fail to achieve complete correction. The standard orbital decompressions were therefore modified to maximize the degree of volumetric increase behind the axis of the globe. In 15 orbits, the preoperative exophthalmos averaged 9.5 mm, whereas the postoperative exophthalmos was 4.1 mm. Postoperative CT study demonstrated that the remaining posterior orbital wall, combined with the persistently increased intraocular muscle volume, blocked retrodisplacement of the globe, despite adequate total volumetric increase. The increased muscle volume varied from 2 to 5 cc. Despite this residual exophthalmos, the modified four-wall expansion provides excellent aesthetic results with visual improvement and resolution of chemosis and exposure keratitis.

Cirrus cloud transmittance and backscatter in the infrared measured with a CO(2) lidar.

Two independent methods of measuring the transmittance of cirrus clouds are compared. Both used a CO(2) pulsed Doppler lidar at a wavelength of 10.59 microm. The first method used backscatter from the calibration target El Chichon stratospheric cloud that was present over Boulder in 1982 and 1983. The second method used conical lidar scans at different zenith angles when uniform cirrus decks were present. Extinction coefficients measured from both methods average 0.1 km(-1) for tenuous cirrus 1.0 km thick to 0.78 km(-1) for cirrus several kilometers thick. There is a wide standard deviation in extinction values. Extinction-tobackscatter ratios S vary from <1000 sr for tenuous clouds to 2600 sr for dense clouds. Mie scattering and extinction calculations for spherical ice particles of 10-50 microm in radius lead to ratios S > 2000 sr, so long as the ice absorption is entered into the calculations. The backscattering ratio for ice cylinders is 1 order of magnitude lower than for spheres. Backscatter in the IR may, therefore, be reasonably well modeled by some combination of spheres and cylinders. Cloud thickness statistics from lidar returns show that cirrus decks average ~500 m thick. Clouds thinner than 300 m were often overlooked by the unaided surface-based observer. These preliminary results are in rather close agreement with the LOWTRAN 6 cirrus cloud model predictions.