Der Anaesthesist
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Randomized Controlled Trial Clinical Trial Controlled Clinical Trial
[Age-related correlation between EEG parameters and depth of anesthesia under propofol. Effect of fentanyl].
This study was designed to determine the relationship between the electroencephalogram (EEG) and clinical signs of depth of anaesthesia during induction of anaesthesia by slow infusion of propofol (18 mg/kg.h). ⋯ Different clinical signs corresponding to different levels of depth of anaesthesia could be differentiated by their EEG parameters. The EEG stage allowed better differentiation of the clinical conditions than the single-parameter EEG derivatives median and SEF. The results of this study show that EEG monitoring provides information about depth of anaesthesia.
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The separation of whole blood into components is the state-of-the-art in transfusion of allogeneic blood. The main reasons are the negative effects of the buffy coat and the need for FFP. Nevertheless, especially in Germany whole blood is being rejected more and more even as autologous blood. However, most of the negative effects of the buffy coat do not apply to autologous blood. Additionally, these patients usually do not develop coagulation disorders and therefore do not need plasma as a hemostatic component. On the other hand, separation into components of autologous blood leads to an increase of costs and to logistic problems that restrict autologous blood predeposit to a few institutions. Therefore, we have reviewed the literature in order to find a scientific basis for this. ⋯ Whole blood (resuspended in CPDA-1) and red cell units (stabilized in CPDA-1 or additive solutions) with a different buffy coat or leucocyte content have comparable pH values and red cell 2,3-DPG and ATP concentrations at the end of the approved storage time. The potassium load of a whole blood unit appears to be higher than red cell concentrates, but this is to some extent caused by the higher plasma content of whole blood and is not thought to be a clinically relevant problem for patients receiving only a few units. A number of studies demonstrate that dependent upon the leucocyte content of a red cell unit, leucocyte metabolites and enzymes are released and accumulate during storage. A detrimental influence on the integrity of the red cell membrane was found in several in vitro studies. Nevertheless, a significant improvement in red cell survival by leucocyte reduction was detected by only one group. Undoubtedly, nonhemolytic febrile transfusion reactions (NHFTR) are generally caused by an antibody-antigen interaction due to the transfusion of allogeneic buffy coat. On the other hand, there is some evidence that non-specific immunological mechanisms such as the release of histamine or cytokines are also capable of causing NHFTR. Thus, these reactions are expected to occur in autologous blood transfusion. However, so far, there are no data about the frequency and severity of these reactions and whether they are more likely to emerge after transfusion of blood units with a particular preparation. Blood transfusions can cause septic complications due to bacterial contamination of the transfused units. These fatal but rare complications may be reduced by pre-storage filtration of blood, but there is no indication that buffy coat reduction is effective. Three cases with septic complications have been reported after autologous transfusion, in two of which red cell concentrates (at least one was free of buffy coat) had been used. Thus, there is no justification for the conclusion that the risk of septic complications is increased by transfusion of whole blood. After all, whole blood and red cell concentrates exhibit only minor differences in relevant in vitro parameters. Hence, a higher incidence of adverse effects following the transfusion of autologous whole blood compared to autologous red cell concentrations is unlikely. Therefore, the 24 h in vivo recovery is considered to be the most valid criterion to assess the quality of red cell preparations.(ABSTRACT TRUNCATED)
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Several methods have been developed to quantify central anaesthetic effects and monitor awareness during general anaesthesia. The most important of these are the PRST score, calculated from changes in blood pressure, heart rate, sweating, and tear production, the isolated forearm technique, where the patient is allowed to move during surgery, the processed electroencephalogram (EEG) and the derived parameters median frequency (MF) and spectral-edge frequency (SEF), and mid-latency auditory evoked potentials (MLAEP). In clinical practice, the application of individual doses of anaesthetics is generally guided by autonomic vegetative clinical signs such as changes in blood pressure, heart rate, sweating, and tear production, quantified as the PRST score. ⋯ MLAEP are suppressed in a dose-dependent fashion by many general anaesthetics and correlate with wakefulness, awareness, and explicit and implicit memory during anaesthesia and seem to be a promising method of monitoring awareness during anaesthesia. Nevertheless, future studies will have to determine threshold values for the different MLAEP parameters for intraoperative awareness and explicit and implicit recall of intraoperatively presented information for the different commonly used anaesthetics. Only then will it be possible to determine the usefulness of the method in clinical practice.
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Three cases are presented dealing with rare lethal complications during the insertion of pulmonary artery catheters (PAC). Complications resulting from catheter insertion have been reported on numerous occasions; we report further examples of inadequate insertion techniques. ⋯ Based on our observations, we believe the low complication rate associated with PAC insertion has led to deviations from the normal guidelines by some physicians. Despite adequate precautions and insertion technique, iatrogenic lesions cannot be avoided in all cases because of pre-existing risk factors. For the evaluation of catheter-induced complications and the development of a risk profile, more autopsies as well as more detailed clinical documentation would be necessary.