Der Anaesthesist
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Randomized Controlled Trial Clinical Trial
[Methemoglobinemia due to prilocaine after plexus anesthesia. Reduction by prophylactic administration of ascorbic acid?].
This study investigated in vivo and in vitro kinetics of o-toluidine-induced methemoglobinemia and the influence of ascorbic acid on resulting methemoglobin concentrations. o-Toluidine is a metabolite of prilocaline and ascorbic acid is recommended for treatment of methemoglobinemia as an alternative to methylene blue. ⋯ In vitro high concentrations of ascorbic acid are able to reduce the resulting methemoglobin concentration 360 min after addition of 50 micrograms/ml o-toluidine. The application of 2,000 mg ascorbic acid i.v. before plexus anesthesia with prilocaine does not reduce the concentration of methemoglobin.
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Monitoring and management of intravascular volume status is of crucial importance in critically ill patients. Hypovolemia, induced by hemorrhage or pathologic fluid shifts in the presence of systemic inflammation, is frequently the cause for hemodynamic instability and hypotension. This deficit of central blood volume leads to a reduction in biventricular cardiac preload. ⋯ Several conventional parameters of systemic hemodynamic monitoring such as the cardiac filling pressures CVP and PAOP, the estimation of the left ventricular end-diastolic area (LVEDA) by echocardiography and measurement of central blood volumes as the right-ventricular end-diastolic volume (RVEDV) or the global end-diastolic volume (GEDV) by thermodilution are frequently used for preload monitoring. Further, functional preload parameters such as the left ventricular stroke volume variation (SW), describing the specific interactions of the heart and the lungs under mechanical ventilation, have been recently proposed to be useful for predicting fluid responsiveness. Thus, it is the aim of the present article to analyze these different concepts of hemodynamic monitoring regarding their usefulness and clinical applicability to predict fluid responsiveness at the bedside.
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Aortocaval compression syndrome (supine hypotensive syndrome) represents a common complication mainly of late pregnancy, although the syndrome has been described to occur as early as 16 weeks of gestation. The nature and severity of symptoms range from unspecific complaints to severe maternal hypotension, loss of consciousness, cardiovascular collapse, and consecutive fetal depression. Predominantly, the syndrome is provoked by placing the parturient supine. ⋯ For the anesthetist, cesarean section is most relevant, because of the coincidence of several risk factors. The following article begins by reviewing the pathophysiology of the syndrome, known risk factors and anesthesiological procedures that predispose to the syndrome. The second part is concerned with prophylactic measures and therapeutic options, together with the discussion of a clinically practicable algorithm.
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Ambulatory surgical care is intended to save healthcare expenditure from the economical viewpoint. From the patients point of view significant advantages as well as specific disadvantages of ambulatory surgery are known. ⋯ Reducing the surgical trauma by minimally invasive surgical techniques and very good controllability by modern anesthesia concepts is making the management of the postoperative period crucial for successful ambulatory surgery. Most of the complications and common problems during the postoperative period, such as pain, nausea and vomiting, are not specific for ambulatory surgery, but management places an increasing burden of responsibility not only on general and specialised physicians, but also on other health professionals, patients, and family members.
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In Germany the predominant standard of preoperative care for elective surgery is fasting after midnight, with the aim of reducing the risk of pulmonary aspiration. However, for the past several years the scientific evidence supporting such a practice has been challenged. Experimental and clinical studies prove a reliable gastric emptying within 2 h suggesting that, particularly for limited intake of clear fluids up to 2 h preoperatively, there would be no increased risk for the patient. ⋯ They recommend a more liberal policy regarding per os intake of both liquid and solid food, with consideration of certain conditions and contraindications. The following article reviews the literature and gives an overview of the scientific background on which the national guidelines are based. The intention of this review is to propose recommendations for preoperative fasting regarding clear fluids for Germany as well.