Der Anaesthesist
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Induced hypotension is defined as a reduction in mean arterial blood pressure to 50-60 mm Hg in normotensive subjects. The aim of induced hypotension is to decrease intraoperative blood loss, decrease the need for blood transfusions and improve operating conditions. Most studies indicate that induced hypotension can decrease intraoperative blood loss by 50% in many surgical procedures; however, some studies report that blood loss is not significantly reduced. ⋯ Thus, major contraindications of induced hypotension are severe coronary artery disease, hypertension combined with arteriosclerosis of cerebral vessels and increased intracranial pressure in patients with cerebral disease. Complications are rare in otherwise healthy patients, but may be higher in elderly patients and those with underlying organ dysfunction. Therefore, careful assessment and selection of patients, together with consideration of the potential complications, appropriate choice of drugs and invasive beat-by-beat monitoring, are essential for the safe practice of induced hypotension.
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Only 53%-58% of patients with a subarachnoid haemorrhage (SAB) following the rupture of a cerebral aneurysm survive without neurological damage. Morbidity and mortality are closely related to the delayed ischaemic neurological deficit due to cerebral vasospasm. The following review gives an account of pathophysiological mechanisms; the importance of treatment with calcium antagonists, hypervolaemic haemodilution, and induced arterial hypertension is discussed in light of the current literature. ⋯ In view of the autoregulatory disturbances, systemic hypotension with its danger of decreased CBF must be prevented. The importance of hypervolaemic haemodilution and/or induced arterial hypertension is not clear. Despite therapeutic efforts, the number of patients who have survived a SAB without a substantial neurological deficit has not increased.
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Propofol is commercially available as Disoprivan. It is formulated as an aqueous emulsion with 1% 2,6-diisopropylphenol, 10% soya bean oil, 2,5% glycerol and 1.2% egg phosphatide. Since 1986, propofol has been used as a sedative drug in the ICU and is highly valued for its numerous positive qualities. ⋯ First, cardiovascular depression, especially if potentiated by drugs such as beta- and Ca-entry blockers, may lead to hypotensive episodes. Potential problems (drug tolerance, hypertriglyceridaemia) may be revealed in long-term studies. As long as no such studies have been presented, the authors believe that it is too early to consider propofol the ideal drug for long-term sedation.
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The safety of blood and blood components is an important aspect of transfusion medicine. Even if absolute safety of blood products cannot be achieved, this goal has come closer due to significant improvements. These include: (1) exact donor registration; (2) component preparation according to legal requirements and GMP guidelines; (3) determination of all relevant diagnostic parameters according to GMP/GLP guidelines; (4) adequate storage of products; and (5) and often underestimated parameter ensuring safety, strict guidelines for the use of blood products in the treatment of patients. Some of the results of the first Graz Consensus Conference on Transfusion Medicine are presented.