Evaluation of hemodynamic effects of xenon in dogs undergoing hemorrhagic shock

OBJECTIVES: The anesthetic gas xenon is reported to preserve hemodynamic stability during general anesthesia. However, the effects of the gas during shock are unclear. The objective of this study was to evaluate the effect of Xe on hemodynamic stability and tissue perfusion in a canine model of hemorrhagic shock. METHOD: Twenty-six dogs, mechanically ventilated with a fraction of inspired oxygen of 21% and anesthetized with etomidate and vecuronium, were randomized into Xenon (Xe; n = 13) or Control (C; n = 13) groups. Following hemodynamic monitoring, a pressure-driven shock was induced to reach an arterial pressure of 40 mmHg. Hemodynamic data and blood samples were collected prior to bleeding, immediately after bleeding and 5, 20 and 40 minutes following shock. The Xe group was treated with 79% Xe diluted in ambient air, inhaled for 20 minutes after shock. RESULT: The mean bleeding volume was 44 mL.kg-1 in the C group and 40 mL.kg-1 in the Xe group. Hemorrhage promoted a decrease in both the cardiac index (p<0.001) and mean arterial pressure (p<0.001). These changes were associated with an increase in lactate levels and worsening of oxygen transport variables in both groups (p<0.05). Inhalation of xenon did not cause further worsening of hemodynamics or tissue perfusion markers. CONCLUSIONS: Xenon did not alter hemodynamic stability or tissue perfusion in an experimentally controlled hemorrhagic shock model. However, further studies are necessary to validate this drug in other contexts.

Influence of plasma arc and quartz-tungsten-halogen curing lights on the polymerization of orthodontic composite resin / Influência das fontes fotoativadoras xenon e halógena na polimerização de resina composta para colagem ortodôntica

PURPOSE: To analyze, in vitro, the influence of a quartz-tungsten-halogen (QTH) and a plasma arc (PAC) on the degree of conversion and hardness of a composite resin, as well as the heat generated by the units. METHODS: Transbond XT disks were prepared and light-cured for 10, 20 and 30 seconds with a QTH (Curing Light XL 3000) or with a PAC (Apollo 95E) for 1, 2 and 3 seconds. The composite resin polymerization was evaluated by infrared spectrophotometry (FTIR) and Knoop hardness number (KHN). The temperature at the curing tip was evaluated. The results were analyzed using ANOVA and Tukey test (α=0.05). RESULTS: According to FTIR and KHN, the polymerization of the composite resin was statistically higher with the QTH. The temperature obtained with the QTH 20 s (45.44ºC) and 30 s (45.84ºC) was statistically higher than the QTH 10 s (39.90ºC). The PAC 1 s (27.12ºC), 2 s (28.48ºC) and 3 s (29.96ºC) presented the lowest temperature and did not differ statistically among them. CONCLUSION: Transbond XT light-activated for 10, 20 and 30 seconds with the QTH presented higher degree of conversion and hardness in comparison with those obtained with the PAC for 1, 2 and 3 seconds, and the QTH generated more heat than the PAC.

OBJETIVO: Analisar, in vitro, as fontes luminosas Halógena (QTH) e Xenon (PAC) no grau de conversão e dureza de uma resina composta e também o calor gerado por estas unidades. METODOLOGIA: discos com resina Transbond XT foram fotoativados por 10, 20 e 30 segundos com QTH (Curing light XL 3000) ou com PAC (Apollo 95E) por 1, 2 e 3 segundos. A resina composta foi analisada por meio de espectrofotometria infravermelha (FTIR) e pelo teste de dureza Knoop (KHN). A temperatura na ponta dos aparelhos foi também avaliada. Os resultados foram analisados usando ANOVA e Tuckey test (α=0.05). RESULTADOS: Conforme FTIR e KHN a polimerização do compósito foi estatisticamente maior com QTH. A temperatura obtida do QTH com 20 segundos (45,44ºC) foi estatisticamente maior do que com 10 segundos (39,90ºC). O PAC com 1, 2 e 3 segundos apresentou as temperaturas mais baixas e não diferem estatisticamente entre si. CONCLUSÃO: A resina Transbond XT fotoativada por 10, 20 e 30 segundos com QTH apresentou maior grau de conversão e dureza em comparação com PAC por 1, 2 e 3 segundos. O QTH produziu mais calor que o PAC.