Der Anaesthesist
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Unexpected bleeding in the perioperative period is largely caused by impaired inherited or drug-induced primary haemostasis. Standard tests for plasma coagulation are predominantly employed to gauge the risk of bleeding. ⋯ Accordingly, healthy patients of the American Society of Anesthesiologists (ASA) grades I and II without any suspicion of impaired haemostasis who are scheduled for procedures without expected transfusion requirements, need no standard tests for coagulation. In all other patients (including patients taking medication affecting coagulation, or patients who are unable to provide adequate information) platelet count, platelet function, aPTT, PT, and fibrinogen levels should be assessed.
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Pharmacokinetic models can be differentiated into two groups: physiological-based models and empirical models. Traditionally the pharmacokinetics of volatile anaesthetics are described using physiological-based models together with the respective tissue-blood distribution coefficients. The compartments of the empirical model have no anatomical equivalents and are merely the product of the mathematical procedure for parameter estimation. ⋯ In clinical practice volatile anaesthetics are normally combined with N(2)O and/or opioids. This results in an additive interaction between volatile anaesthetics and N(2)O but a synergistic interaction of volatile anaesthetics with opioids. However, there are relatively few investigations on the interactions between the clinically widely used combination of volatile anaesthetics, N(2)O and opioids.
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Randomized Controlled Trial
[Preoperative administration of angiotensin-converting enzyme inhibitors].
The discussion about perioperative withdrawal or continuation of angiotensin-converting enzyme inhibitors (ACEI) remains controversial. Should it be continued to avoid peaks in blood pressure and heart rate during anesthesia? Or should it be discontinued the day before to avoid clinically relevant hypotonia? What is the greater risk? Since there are only a few studies dealing with this question, we compared the cardio-circulatory reaction during anesthesia after withdrawal and with continuation of ACEI therapy. ⋯ The continuation of ACEI therapy in the morning is not associated with a better control of blood pressure and heart rate but causes a more pronounced hypotension which forced a therapy more often. Patients chronically treated with ACEI should receive the ACEI the last time on the day before the operation and not with the premedication in the morning.
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Introduction of the laryngeal mask airway (LMA) has been a revolutionary development in airway management over the last decades. It was first used clinically in 1981 by A. ⋯ Originally intended as a substitute for conventional mask respiration for short periods of general anaesthesia, the laryngeal mask is in the meantime used in many areas as an alternative to elective endotracheal intubation as well as an option for controlling difficult airways. This contribution provides an overview of the basics as well as practical aspects of LMA use, and discusses the possibilities and limitations of the laryngeal mask in daily practice.