Browsing by Author "Kronenberg, P"
Now showing 1 - 10 of 12
Results Per Page
Sort Options
- Advances in Lasers for the Treatment of Stones-a Systematic ReviewPublication . Kronenberg, P; Somani, BPURPOSE OF REVIEW: Laser lithotripsy is increasingly used worldwide and is a continuously evolving field with new and extensive research being published every year. RECENT FINDINGS: Variable pulse length Ho:YAG lithotripters allow new lithotripsy parameters to be manipulated, and there is an effort to integrate new technologies into lithotripters. Pulsed thulium lasers seem to be a viable alternative to holmium lasers. The performance of similar laser fibers varies from manufacturer to manufacturer. Special laser fibers and "cleaving only" fiber tip preparation can be beneficial for the lithotripsy procedure. Different laser settings and the surgical technique employed can have significant impact on the success of laser lithotripsy. When safely done, complications of laser lithotripsy are rare and concern the endoscopic nature of procedure, not the technology itself, making laser lithotripsy one of the safest tools in urology. Laser lithotripsy has had several new developments and more insight has been gained in recent years with many more advances expected in the future.
- Are we all doing it wrong? Influence of stripping and cleaving methods of laser fibers on laser lithotripsy performance.Publication . Kronenberg, P; Traxer, OPURPOSE: We assessed whether stripping and cleaving the laser fiber tip with specialized tools, namely laser fiber strippers, or ceramic or metal scissors, would influence lithotripsy performance. MATERIALS AND METHODS: Laser fiber tips were stripped with a specialized laser fiber stripper or remained coated. The tips were then cleaved with metal or ceramic scissors. Laser lithotripsy experiments were performed with the 4 fiber tip combinations using an automated laser fragmentation testing system with artificial stones made of plaster of Paris or BegoStone Plus (Bego, Lincoln, Rhode Island). High frequency-low pulse energy (20 Hz and 0.5 J) and low frequency-high pulse energy (5 Hz and 2.0 J) settings were used for 30 seconds. Fissure width, depth and volume, and laser fiber tip photos were analyzed. RESULTS: Coated laser fiber tips always achieved significantly higher ablation volumes (sometimes greater than 50%) than stripped laser fiber tips (p <0.00001) regardless of cleaving scissor type, stone material or lithotripter setting. Coated fiber tips cleaved with metal scissors ablated as well as those cleaved with ceramic scissors (p = 0.16). However, stripped fibers were much less ablative when they were cut with metal scissors compared to ceramic scissors (p <0.00001). Harder stone material decreased ablation volume (p <0.00001). Low frequency-high pulse energy settings were an average of 3 times more ablative than high frequency-low pulse energy settings (p <0.00001). Stripping the fibers, a harder stone material and low frequency-high pulse energy settings were associated with increased fiber tip degradation. CONCLUSIONS: Coated laser fibers provided better lithotripsy performance and metal scissors were as good as ceramic scissors to cleave coated fibers. This knowledge may improve and simplify the way that laser lithotripsy procedures are done worldwide.
- Cistadenoma multiquístico da próstata: caso clínicoPublication . Furtado, A; Féria, R; Silva, A; Kronenberg, P; Alves, C; Cardoso, POs cistadenomas prostáticos são tumores raros e como tal pouco reportados na literatura. Descreve-se o caso clínico de um indíviduo do sexo masculino, com 48 anos de idade, assintomático e sem antecedentes pessoais do foro urológico, referenciado à consulta por PSA elevado e achado ecográfico de volumosa massa pélvica. A cistoscopia apresentava, estritamente, um abaulamento extrínseco da parede vesical póstero-inferior. Levou-se a cabo a excisão cirúrgica da massa tumoral e a sua análise anátomo-patológica caracterizou-a como cistadenoma multiquístico da próstata.
- A experiência dos Serviços de Urologia: litíase urináriaPublication . Graça, B; Kronenberg, P; Furtado, A; Abreu, R; Lopes, SOs autores fazem uma descrição da experiência do Serviço, na cirurgia da litíase dos últimos 10 anos, e destacam o actual arsenal cirúrgico disponível.
- Giant nephrothoracic abscess: a misleading disease, a surgical challenge, and an unexpected complicationPublication . Kronenberg, P; Graça, B; Coelho, MA rare case of perinephric abscess with unilateral secondary pulmonary involvement that was further complicated by spillover of purulent content into the contralateral lung is reported here. Its diagnosis, treatment, and evolution are described and discussed along with certain features of nephropulmonary fistulas. The diagnosis of these abscesses is difficult, largely because of the paucity of primary symptoms and the frequent presence of misleading secondary symptoms. Deceptive cases like this one highlight the importance of its contemplation in every physician's differential diagnosis.
- In vitro fragmentation efficiency of holmium: yttrium-aluminum-garnet (YAG) laser lithotripsy--a comprehensive study encompassing different frequencies, pulse energies, total power levels and laser fibre diametersPublication . Kronenberg, P; Traxer, OOBJECTIVE: To assess the fragmentation (ablation) efficiency of laser lithotripsy along a wide range of pulse energies, frequencies, power settings and different laser fibres, in particular to compare high- with low-frequency lithotripsy using a dynamic and innovative testing procedure free from any human interaction bias. MATERIALS AND METHODS: An automated laser fragmentation testing system was developed. The unmoving laser fibres fired at the surface of an artificial stone while the stone was moved past at a constant velocity, thus creating a fissure. The lithotripter settings were 0.2-1.2 J pulse energies, 5-40 Hz frequencies, 4-20 W power levels, and 200 and 550 μm core laser fibres. Fissure width, depth, and volume were analysed and comparisons between laser settings, fibres and ablation rates were made. RESULTS: Low frequency-high pulse energy (LoFr-HiPE) settings were (up to six times) more ablative than high frequency-low pulse energy (HiFr-LoPE) at the same power levels (P < 0.001), as they produced deeper (P < 0.01) and wider (P < 0.001) fissures. There were linear correlations between pulse energy and fragmentation volume, fissure width, and fissure depth (all P < 0.001). Total power did not correlate with fragmentation measurements. Laser fibre diameter did not affect fragmentation volume (P = 0.81), except at very low pulse energies (0.2 J), where the large fibre was less efficient (P = 0.015). CONCLUSIONS: At the same total power level, LoFr-HiPE lithotripsy was most efficient. Pulse energy was the key variable that drove fragmentation efficiency. Attention must be paid to prevent the formation of time-consuming bulky debris and adapt the lithotripter settings to one's needs. As fibre diameter did not affect fragmentation efficiency, small fibres are preferable due to better scope irrigation and manoeuvrability.
- Lithotripsy Performance of Specially Designed Laser Fiber TipsPublication . Kronenberg, P; Traxer, OWe evaluated and compared a standard laser lithotripsy fiber to laser fibers claimed to have lithotripsy performance enhancing features. MATERIALS AND METHODS: A special AccuMax™ 200 polished tip fiber and an AccuTrac™ ball-shaped tip fiber, each with an approximately 240 μm core, were compared to a standard 272 μm core fiber (Rocamed™). The polished and ball-shaped tip fibers were used and reused without preparation. The standard fiber was stripped and cleaved according to manufacturer instructions after each experiment. An automated laser fragmentation testing system was used to perform multiple 30-second laser lithotripsy experiments. To mimic most typical lithotripsy conditions soft and hard stone materials were used with high frequency, low pulse energy (20 Hz and 0.5 J) or with low frequency, high pulse energy (5 Hz and 2.0 J) lithotripter settings. Ablation volumes and laser fiber tip photographs before and after lithotripsy were compared. RESULTS: The standard and ball-shaped tip fibers did not differ in ablation volume (p = 0.72) but they ablated 174% and 188% more stone, respectively, than the polished tip fiber (p <0.0001). The ball-shaped tip showed remarkable fiber tip degradation after short-term use at low frequency, high pulse energy settings. When high pulse energy settings were applied first even for short-term use, the ablation volume achieved by the polished and ball-shaped tip fibers at high frequency, low pulse energy settings decreased more than 20%. CONCLUSIONS: The standard laser fiber was as good as and sometimes better than the specially designed fibers. Rapid degradation of the specially designed laser fiber tips strongly limits their general usefulness but ball-shaped tip fibers may be useful in specific situations.
- Litíase aparelho urinário superior: tratamento cirúrgicoPublication . Kronenberg, P; Furtado, A; Dores, J; Coelho, M
- Oncocitoma renal: tem a URO-TC utilidade no diagnóstico histológico?Publication . Dores, J; Kronenberg, P; Santos, PB; Ferreira, S; Gomes, FCIntrodução: Ao longo dos últimos anos, a crescente utilização de exames imagiológicos, nomeadamente ecografia e tomografia computorizada (TC), traduziu-se num aumento do diagnóstico incidental de tumores renais, sobretudo pequenas massas renais (<4 cm). O conhecimento de que até 30% destas massas podem ser benignas, entre elas os oncocitomas, levou á procura de métodos de diagnóstico mais eficazes, de forma a evitar situações de sobretratamento e de forma a tornaram-se decisões terapêuticas mais fundamentadas. Objectivos: Analisar retrospectivamente uma série de tumores renais histologicamente comprovados, nomeadamente oncocitomas e carcinomas de células renais (CCR), e verificar se existem diferenças morfológicas e/ou nos padrões de captação de contraste através da URO-TC. Material e métodos: Identificámos todos os tumores renais entre 2004-2015 com o diagnóstico histológico de oncocitoma e de CCR. Estes resultados foram obtidos por biopsia do tumor renal, tumorectomia/nefrectomia parcial ou nefrectomia radical. Registámos e comparámos as características morfológicas e os padrões de captação de contraste na fase nefrográfica com medição de unidades de Hounsfield (HU) dos oncocitomas e dos CCR (células claras), selecionados de acordo com a dimensão (aprox. idêntica á dos oncocitomas) e obtidos na sequência de tumorectomia renal ou nefrectomia radical. Resultados: Identificaram-se 16 CCR e 31 oncocitomas, dos quais 15 foram excluídos por não termos acesso ás imagens de TC no sistema informático. A dimensão média dos oncocitomas foi 3,7 cm (1,8 – 14) e a dos CCR 3,5 cm (1,9 – 8,4). A atenuação de contraste média dos oncocitomas e dos CCR na fase sem contraste foi de 33 HU e 32 HU, respectivamente. Na fase nefrográfica, a captação média de contraste para os oncocitomas foi de 47,5 HU e 47,4 HU para os CCR. Na fase nefrográfica, a diferença de atenuação entre os oncocitomas e o parênquima renal normal foi 43,5 HU e a diferença de atenuação entre os CCR e o parênquima renal normal foi 59,7 HU. Estes resultados foram estatisticamente significativos (p<0,05). Não se identificaram outras alterações na fase excretora da TC, nem diferenças relevantes de carácter morfológico, nomeadamente nos contornos das lesões, presença de calcificações, ou de cicatriz central. Conclusões: Na avaliação imagiológica por URO-TC, nomeadamente na fase nefrográfica, parece existir uma tendência para maior isodensidade dos oncocitomas em relação ao parênquima renal normal. Este achado poderá contribuir para uma melhor decisão terapêutica, na medida em que nos pode direccionar para uma biópsia de confirmação em detrimento da excisão cirúrgica.