In-depth characterization of exhaust particles performed on-board a modern cruise ship applying a scrubber.

To comply with environmental regulations, ship operators may adopt exhaust after-treatment devices such as scrubbers or selective catalytic reduction (SCR). Beyond gaseous emission control, these technologies impact the exhaust particles emitted from marine engines to the atmosphere. This study characterizes comprehensively the chemical composition and physical properties of exhaust aerosol particles upstream and downstream a hybrid scrubber operating in open loop mode on-board a modern cruise ship. The study considers two engines, one equipped with SCR and both with scrubber, during engine load conditions of 75 % and 40 %, and the influence of marine gas oil (MGO) use in addition to heavy fuel oil (HFO). At least 4 different particle types were observed in the exhaust based on transmission electron microscopy (TEM) studies both upstream and downstream scrubber, and both scrubber and SCR affected the particle number size distribution (PSD). The geometric mean diameter (GMD) of the particles increased over scrubber both due to removal of nucleation mode particles and particle growth in the scrubber. The scrubber effectively decreased particle number (PN) and, also, non-volatile particles, but the effect depended on particle size and no significant decrease was observed in number of particles above 50 nm, typically comprising black carbon (BC) and in the case of HFO combustion, also asymmetrical metal containing particles. In addition to PN, concentrations of PAH compounds were reduced in the scrubber. The results may be further utilized when including the exhaust aerosol characteristics from ships applying scrubbers to emission inventories, as well as climate and air quality models.

Holmium:YAG laser for urinary stones.

OBJECTIVE: To evaluate the results of Holmium:YAG (Ho:YAG) laser lithotripsy in the treatment of urinary stones. MATERIAL AND METHODS: Between 1993 and 1997, 59 patients with 85 urinary stones were treated with the Ho:YAG laser lithotripsy. Retrospective evaluation was done on the 64 procedures available, comprising 53 ureteric, 8 bladder, and 2 renal calculi, and one stone in a ureterocele. RESULTS: The Ho:YAG laser fragmented all types of calculi. Of 38 patients, 29 (76%) with ureteric stones were stone-free and 7 (18%) had stone fragments smaller than 2 mm left 1-3 months after the lithotripsy, resulting in a total clinical success rate of 95%. The procedure caused four ureteric perforations. One ureteric stricture, after repeated treatments for a Steinstrasse formation, led to nephrectomy. CONCLUSIONS: The Ho:YAG laser was reliable and effective for most of the urinary stones. The largest stones in any location, and stones of hard composition, however, were treated with combined disintegration methods. Four minor ureteric perforations and one ureteric stricture were related to laser use.

A randomized study to compare biodegradable self-reinforced polyglycolic acid spiral stents to suprapubic and indwelling catheters after visual laser ablation of the prostate.

PURPOSE: A randomized controlled study was done to evaluate the efficacy of the self-reinforced polyglycolic acid spiral stent compared to a suprapubic catheter, and combined suprapubic and indwelling catheters in the prevention of urinary retention after visual laser ablation of the prostate. MATERIALS AND METHODS: We studied 72 men with benign prostatic hyperplasia who underwent placement of a suprapubic catheter and visual laser ablation of the prostate. In 27 men in group 1 the self-reinforced polyglycolic acid spiral stent was inserted into the prostatic urethra after visual laser ablation of the prostate, while 23 in group 2 received no other devices. In 22 men in group 3 an indwelling catheter was left in situ for an average of 6.5 days. RESULTS: Voiding began 1 or 2 days postoperatively in 20 of 27 patients (median 1 day) in group 1, and 8 of 23 (median 6 days) in group 2. In 16 of 22 men in group 3 voiding began 1 or 2 days (median 6) after removal of the indwelling catheter. Improvements in patient weighted symptom score, mean peak urinary flow rate and post-void residual volume were significant (p < 0.001) at 6 months of followup in all groups. The overall infection rate was 30%. CONCLUSIONS: The self-reinforced polyglycolic acid spiral stent is superior to the suprapubic catheter alone, and to combined indwelling and suprapubic catheters for the treatment of postoperative urinary retention after laser therapy, offering possibilities for shorter catheterization time.

Cost and effectiveness of different treatment alternatives in urinary stone practice.

The cost and effectiveness of seventy-six consecutive percutaneous nephrolithotomy (PNL) procedures performed during the years 1990-1992, a sample of 425 ESWL patients with 675 treatments from 1991-1992, and 45 successive open pyelolithotomies (PL) performed before the advent of the new stone treatment techniques during the years 1981-1985, were studied for each of the treatment modalities. The costs were counted per patient and based on the cumulative charge of the procedures, cost for in-patient care, and treatment of additional procedures and operatively treated complications. The results showed that the great majority of ESWL patients were treated at a low cost and with few additional procedures and complications compared to PNL, particularly, when stones smaller than 20 mm were treated. Considering all the patients, the cumulative mean hospital cost per patient without the cost for the follow-up was as follows, FIM (pound): PL 33860(4200), PNL 63360(7860), and ESWL 17430(2160). The remarkable number of additional and auxiliary measures (including the pre- and post-operative ESWL procedures) resulted in considerable extra costs for the PNL patients until they were rendered stone-free. Another series comprising 42 successive patients with 48 stone basket procedures (SB) from the years 1981-1985 was retrospectively compared to 42 patients with 50 ureteroscopic stone extractions (URS) between January 1985 and April 1988 before the beginning of the ESWL practice in Finland as well as to 54 patients with 79 ESWL treatments for a lower ureteric stone during the years 1991-1992. The stone-free status after the three procedures until one month was 71, 66, and 60%, with no statistically significant difference. In the group of lower ureteric stones the cumulative mean hospital cost per patient was as follows, FIM (pound): SB 19520(2420), URS 17750(2200), and ESWL 17810(2210). Also in the treatment of lower ureteric stones, ESWL is an equally cost-effective method representing an alternative worth consideration, particularly for patients preferring a minimally invasive urinary stone treatment.

Residual stones after percutaneous nephrolithotomy; sensitivities of different imaging methods in renal stone detection.

Kidneys of 35 renal stone patients treated with percutaneous nephrolithotomy (PNL) were examined at 12-36 months (mean 23 months) after the procedure by plain radiography (PR), conventional linear tomography (LT), computed tomography (CT), and ultrasonography (US) to find out the long-term stone-free rate as well as the accuracy of these imaging methods to detect residual or recurrent renal stones. The present series included 36 kidneys with a 56% postoperative stone-free status examined by plain radiography and a 58% one examined by linear tomography at 12-36 months. CT showed 47% and US 72% of the kidneys to be stone-free, respectively. The sensitivity of CT was superior to plain radiography (P < 0.05), linear tomography (P < 0.05) or US (P < 0.001) in the detection of residual or recurrent stones after percutaneous nephrolithotomy analyzed statistically by McNemar's test. In the same group of 35 patients, which consisted of the above 36 postoperative kidneys together with 19 contralateral kidneys, a total of 55 kidneys were evaluated by the above methods, revealing 56 stones in 31 kidneys. Of these stones 95% were detected by CT, 70% by plain radiography, 68% by linear tomography, and 32% by renal US. Of the 55 kidneys, 14 contained 20 stone fragments smaller than 3 mm, and 26 kidneys carried 43 concrements smaller than 6 mm. The sensitivities of the four imaging methods in the detection of these small fragments were as follows: plain radiography 60% and 60%, linear tomography 55% and 58%, CT 95% and 93%, and US 15% and 26%.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of urinary stones by extracorporeal shock wave lithotripsy.

A total of 1641 ESWL-treatments were performed in 948 patients at Helsinki University Central Hospital between June 1989 and December 1991. In a series of 816 patients and 1287 treatments with data available 681 (76.4%) stones were located in the kidney, 208 (23.3%) in the ureter, and three (0.3%) in the urinary bladder. Auxiliary procedures were performed in 156 (19.1%) and repeated treatments in 300 (36.8%) patients. The most common complication was intensive pain during the procedure in 138 (16.9%) patients. The first 139 patients were followed until six months after their last ESWL-procedure. The six-month stone-free rates of renal and ureteric stones of these patients were 67.4% and 86.7%, respectively. The overall six-month clearance rate was 72.4%.

Results of the management of ureteric stones with the ureterorenoscope.

Eighty ureterorenoscopies (URS) were performed for stone removal in 67 patients between January 1985 and April 1988. The success rates for stone removal were 54% in the lower third of the ureter, 70% in the middle third, 38% in the upper third, and 33% in the renal pelvis. The overall success rate was 42%. Open ureterolithotomy was performed after failed ureteroscopy nine times. There were two perforations of the ureter: one by the hook of the forceps and the other by the dormia basket. No significant late complications occurred in 51 patients after six to 36 months postoperatively. At the moment ureteroscopy is of value particularly in the treatment of lower or middle ureteric stones.

Early experience with percutaneous nephrolithotomy.

Fifty-four percutaneous nephrolithotomy (PNL) procedures were performed in 41 patients between May 1986 and December 1987. Six patients required more than one procedure and there was one failure which was treated by open ureterolithotomy. Most of the stones were initially found in the pelvicalyceal system, one in the lower third and nine in the middle or upper third of the ureter. There were five significant complications: one "steinstrasse" (accumulation of stone fragments in the distal ureter after the procedure), one massive perirenal haematoma, one intramural perforation by a ureteric catheter and two extravasations of irrigation fluid one of which necessitated intensive care. Most of the renal and upper ureteric stones have now been successfully removed percutaneously with good patient tolerance.