Current opinion in anaesthesiology
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Curr Opin Anaesthesiol · Aug 2002
Magnetic resonance imaging anesthesia: new challenges and techniques.
The increasing use of magnetic resonance imaging as a diagnostic modality has led to increased demand for sedation and monitoring during the procedure. This review is to acquaint the reader with the most recent developments in magnetic resonance imaging diagnostics and to describe the evolving techniques and strategies for patient management. ⋯ Anesthesia and sedation during magnetic resonance imaging have a unique set of constraints. However, most of the standards of modern, safe anesthetic care can be met in this environment. The growing experience at many hospitals has demonstrated that a wide range of patients can receive safe care during magnetic resonance imaging.
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Closed-loop systems are able to make decisions on their own and try to reach and maintain a preset target. As a result, they might help the anaesthesiologist in optimizing the titration of drug administration without overshooting, controlling physiological functions and guiding monitoring variables. Thanks to the development of fast computer technology and more reliable pharmacological effect measures, the study of automation in anaesthesia has regained popularity. ⋯ Until now, most of these systems are still under development. The challenge is now to establish fully the safety, efficacy, reliability and utility of closed-loop anaesthesia for its adoption into the clinical setting. Besides the optimization of controlled variables and control models, these systems have to be tested in extreme circumstances.
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The capabilities of interventional radiology are developing faster than perhaps any other branch of medicine. Coupled with and fuelled by parallel advances in computer technology, medical physics and developments in endovascular catheter technology, interventional radiologists are innovating not only replacements for open surgeries, but entirely new therapies as well. This has, however, provided a range of new potential complications for the patient and, in contrast to other areas, presents risks for the anesthesiologist as well. ⋯ In the light of these new developments in interventional radiology there is much research to be done. Further developments in imaging and computer processing technology will doubtless make possible the real time integration of anatomical image with metabolic state and functional anatomy. The impact of the hazards of these new techniques on the safety of anesthesia has, however, been the subject of virtually no research. A particularly needy area will be the ergonomics of the delivery of anesthesia care in these new environments.
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The controversy over preemptive analgesia continues unabated, with studies both supporting and refuting its efficacy. The timing of an analgesic intervention and presence of a placebo control may have significant impact on the interpretation of results and may have led to the premature conclusion that preemptive analgesia is of limited clinical utility. A review of the recent literature using strict definitions of preemptive and preventive analgesia is required in order to clarify the broader issue of the benefits of perioperative analgesia. ⋯ Studies that used a preventive design had a greater likelihood of finding a beneficial effect. The application of preventive perioperative analgesia (not necessarily preincisional) is associated with a significant reduction in pain beyond the clinical duration of action of the analgesic agent, in particular for the N-methyl-D-aspartate antagonists. The classical definition of preemptive analgesia should be abandoned in favor of preventive analgesia. This will broaden the scope of inquiry from a narrow focus on preincisional versus postincisional interventions to one that aims to minimize postoperative pain and analgesic requirements by reducing peripheral and central sensitization arising from noxious preoperative, intraoperative and postoperative inputs.
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Anesthetics influence a wide variety of transmitter- and voltage-gated ion channels in the mammalian central nervous system. At the molecular level, the gamma-aminobutyric acid (GABA) subtype A receptor has emerged as a primary therapeutic target. This review highlights recent advances in our understanding of how anesthetics modify GABA(A) receptor function. ⋯ Detailed insights into anesthetic-GABA(A) receptor interactions have resulted in intense efforts to develop safer drugs that selectively target subtypes of GABA(A) receptors.