Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · May 1994
Comparative StudyComparative histopathology of epidural hydrogel and silicone elastomer catheters following 30 and 180 days implant in the ewe.
New catheter materials, termed Hydrogels, have been developed recently that are stiff until exposed to hydration. The purpose of this study was to compare the 30 and 180 day histopathology of catheters composed of a common silicone elastomer versus a Hydrogel elastomer blend (HEB). Epidural catheters composed of either silicone or HEB were implanted in 19 yearling ewes for either 30 or 180 days. ⋯ The HEB catheter was easily inserted with standard epidural needles facilitated by the inherent stiffness of the catheter prior to hydration. HEB catheters remained patent throughout 30 days of saline injections per implanted ports. Silicone catheters demonstrated increased fibrosis relative to the HEB catheter material in the epidural space and in subcutaneous tissue.
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Acta Anaesthesiol Scand · May 1994
Brain energy metabolism and blood flow during sevoflurane and halothane anesthesia: effects of hypocapnia and blood pressure fluctuations.
The effects of halothane and sevoflurane on cat brain energy metabolism and regional cerebral blood flow (rCBF) were evaluated during normo- and hypocapnia. Brain energy status was evaluated with phosphorous nuclear magnetic resonance spectroscopy (31P-MRS) and rCBF was measured by the hydrogen clearance method. A high concentration of halothane (3 MAC) impaired brain energy metabolism, while even a higher concentration of sevoflurane (4 MAC) had no untoward effect on brain energy metabolism. ⋯ We conclude that hyperventilation and fluctuating blood pressure contribute to the occurrence of abnormal brain energy metabolism during halothane and sevoflurane anesthesia. This is more pronounced with halothane than with sevoflurane. The hypocapnia-induced abnormality during exposure to 2 MAC of either agent was due to decreased CBF associated with low perfusion pressure, indicating that there was no direct effect of these anesthetics on cerebral energy metabolism.