Bladder rupture after blunt trauma: guidelines for diagnostic imaging.

PURPOSE: The purpose of this study was to establish guidelines for diagnostic imaging for bladder rupture in the blunt trauma victim with multiple injuries, in whom the delay caused by unnecessary testing can hamper the trauma surgeon and threaten outcome. METHODS: We undertook chart review (1995-1999) of patients with blunt trauma and bladder rupture at our four institutions and performed focused literature review of retrospective series. RESULTS: Of our 53 patients identified, all had gross hematuria and 85% had pelvic fracture. Literature review revealed similar rates. CONCLUSION: The classic combination of pelvic fracture and gross hematuria constitutes an absolute indication for immediate cystography in blunt trauma victims. Existing data do not support lower urinary tract imaging in all patients with either pelvic fracture or hematuria alone. Clinical indicators of bladder rupture may be used to identify atypical patients at higher risk. Patients with isolated hematuria and no physical signs of lower urinary tract injury may be spared the morbidity, time, and expense of immediate cystographic evaluation.

Holmium: YAG lithotripsy: optimal power settings.

PURPOSE: We tested the hypothesis that holmium:YAG laser lithotripsy speed is best maximized by using low pulse energy at high pulse frequency. MATERIALS AND METHODS: To demonstrate that optical fiber damage increases with pulse energy and irradiation, the 365-microm optical fiber irradiated calcium hydrogen phosphate dihydrate (CHPD), calcium oxalate monohydrate (COM), cystine, magnesium ammonium phosphate hexahydrate (MAPH), and uric acid calculi at pulse energies of 0.5 to 2.0 J. Optical energy output was measured with an energy detector after 10 J to 200 J of total energy. To demonstrate that lithotripsy efficiency varies with power, fragmentation was measured at constant power settings at total energies of 200 J and 1 kJ with the 365-microm optical fiber. Fragmentation was measured for the 272-microm optical fiber at pulse energies of 0.5 J to 1.5 J at 10 Hz. To demonstrate that low pulse energy produces smaller fragments than high pulse energy, fragment size was characterized for COM and uric acid calculi after 0.25 kJ of irradiation using the 272-microm to 940-microm optical fibers at 0.5 J to 1.5 J. RESULTS: Damage to the 365-microm optical fiber was greatest for irradiation of CHPD, followed by MAPH, and COM (P<0.001). There was no significant optical fiber damage after cystine and uric acid lithotripsy. For the 365-microm optical fiber and CHPD, fragmentation after 200 J was greatest for pulse energies < or =1.0 J (P< 0.001). For other compositions, fragmentation was not statistically different among the power settings for constant irradiation. No significant difference was noted in fragmentation for any composition at different pulse energies (1.0 v. 2.0 J) for 1-kJ irradiation. However, for all compositions, the calculated lithotripsy speed was greatest at high power settings (P<0.001). For the 272-microm optical fiber, CHPD fragmentation was greatest for the 1.0-J pulse energy. The mean fragment size and relative quantity of fragments > or =2 mm both increased as pulse energy increased. CONCLUSIONS: Optical fiber degradation varies with stone composition, irradiation, and pulse energy. Holmium:YAG lithotripsy speed is maximized with higher power (either increased pulse energy or higher pulse frequency). Because low pulse energy may be safer and yields smaller fragments than high pulse energy, holmium:YAG lithotripsy speed is best increased by using pulse energies < or =1.0 J at a high repetition rate.

Proteus mirabilis viability after lithotripsy of struvite calculi.

PURPOSE: We tested the hypotheses that Proteus mirabilis viability of struvite calculi differs after exposure to different lithotripsy modalities and that the photothermal mechanism of holmium:YAG lithotripsy is antibacterial. MATERIALS AND METHODS: Human calculi of known struvite composition (greater than 90% magnesium ammonium phosphate hexohydrate) were incubated with P. mirabilis. Calculi were randomly distributed and fragmented with no lithotripsy (controls), or shock wave, intracorporeal ultrasonic, electrohydraulic, pneumatic, holmium:YAG or pulsed dye laser lithotripsy. After lithotripsy fragments were sonicated and specimens were serially plated for 48 hours at 38C. Bacterial counts and the rate of bacterial sterilization were compared. RESULTS: Median bacterial counts (colony-forming units per ml.) were 8 x 10(6) in controls and 3 x 10(6) in shock wave, 3 x 10(7) in ultrasonic, 4 x 10(5) in electrohydraulic, 8 x 10(6) in pneumatic, 5 x 10(4) in holmium:YAG and 1 x 10(6) in pulsed dye laser lithotripsy cases (p <0.001). The rate of bacterial sterilization was 50% for holmium:YAG lithotripsy treated stones versus 0% for each of the other cohorts (p <0.01). CONCLUSIONS: P. mirabilis viability varies among lithotrites. The photothermal mechanism of holmium:YAG lithotripsy is antibacterial.