[Processed EEG for personalized dosing of anesthetics during general anesthesia]. / Das prozessierte EEG zur personalisierten Dosierung von Anästhetika während Allgemeinanästhesie.

Electroencephalogram (EEG)-guided anesthesia is indispensable in modern operating rooms and has become established as the standard form of monitoring. Many anesthesiologists rely on processed EEG indices in the hope of averting anesthesia-related complications, such as intraoperative awareness, postoperative delirium and other cognitive complications in their patients. This educational review aims to provide information on the five most prevalent monitors used to guide depth of sedation during general anesthesia. This article elucidates the principles underpinning the application of these monitors where known, which are generally based on power in various EEG frequency bands and on the burst suppression pattern. Convinced that EEG-guided anesthesia has the potential of benefitting many surgical patients, it is felt that many basic principles and shortcomings of processed EEG indices need to be better understood in the clinical practice. After discussing the different monitors and clinically relevant data from the literature, the article gives a short practical guidance on how to critically interpret processed EEG information and troubleshooting of confounded indices in the context of clinical situations.

[The quantitative EEG in electroencephalogram-based brain monitoring during general anesthesia]. / Das quantifizierte EEG im elektroenzephalogrammbasierten Monitoring während Allgemeinanästhesie.

The electroencephalogram (EEG) is increasingly being used in the clinical routine of anesthesia in German-speaking countries. In over 90% of patients the frontal EEG changes somewhat predictably in response to administration of the normally used anesthetic agents (propofol and volatile gasses). An adequate depth of anesthesia and appropriate concentrations of anesthetics in the brain generate mostly frontal oscillations between 8 and 12 Hz as well as slow delta waves between 0.5 and 4 Hz. The frontal EEG channel is well-suited for avoidance of insufficient depth of anesthesia and excessive administration of anesthetics. This article explains the clinical interpretation of the most important EEG patterns and the biophysical background. Also discussed are important limitations and pitfalls for the clinical routine, which the anesthetist should know in order to utilize the EEG as an admittedly incomplete but clinically extremely important parameter for the level of consciousness.

A Method for Generating Simulated Plasmodes and Artificial Test Clusters with User-Defined Shape, Size, and Orientation.

We present a simple method for generating simulated plasmodes and artificial test clusters with user-defined shape, size, and orientation. Our method differs from other cluster generation techniques in that it focuses on the validity of the cluster indicators. For J clusters, indicator validity is defined as the squared correlation ratio between the cluster indicator (i.e., the observed variable) and J-1 dummy variables. The within-cluster correlation structure and the univariate distributions of the cluster indicators are specified with procedures outlined by Fleishman (1978) and Vale and Maurelli (1983). Simulation results illustrate the utility of the method for cluster analysis evaluation research.

The retained surgical sponge.

OBJECTIVE: A review was performed to investigate the frequency of occurrence and outcome of patients who have retained surgical sponges. METHODS: Closed case records from the files of the Medical Professional Mutual Insurance Company (ProMutual, Boston, MA) involving a claim of retained surgical sponges were reviewed for a 7-year period. RESULTS: Retained sponges occurred in 40 patients, comprising 48% of all closed claims for retained foreign bodies. A falsely correct sponge count after an abdominal procedure was documented in 76% of these claims. Ten percent of claims involved vaginal deliveries and minor non-body cavity procedures, for which no sponge count was performed. Total indemnity payments were $2,072,319, and defense costs were $572,079. In three cases, the surgeon was deemed responsible by the court despite the nursing staff's admitting liability and evidence presented that the surgeon complied completely with the standard of care. A wide range of indemnity payments was made despite a remarkable similarity of outcome in the patients studied. CONCLUSIONS: Despite the rarity of the reporting of a retained surgical sponge, this occurrence appears to be encountered more commonly than generally is appreciated. Operating teams should ensure that sponges be counted for all vaginal and any incisional procedures at risk for retaining a sponge. In addition, the surgeon should not unquestioningly accept correct count reports, but should develop the habit of performing a brief but thorough routine postprocedure wound/body cavity exploration before wound closure. The strikingly similar outcome for most patients would argue for a standardized indemnity payment being made without the need for adversarial legal procedures.