[Is the combination of remifentanil and propopfol suitable for transsphenoid resection of the hypophysis?]. / Eignet sich die Kombination von Remifentanil und Propofol für transsphenoidale Resektionen an der Hypophyse?

In a multi-center trial, the feasibility of combining remifentanil (RF) and target-controlled infusion of propofol (P) for patients undergoing transsphenoidal resection of the pituitary gland was tested. After IRB approval, 74 patients (29 male/45 female) were included in the study. The concentration of RF and the target concentration of P were recorded as were heart rate (HR) and mean arterial blood pressure (MAP). For intubation the RF dosage was 0.26 +/- 0.06 microgram.kg-1.min-1 and the target concentration of P was 3.16 +/- 0.63 micrograms.ml-1. After induction, HR and MAP decreased significantly. The painful events of the operation were preparation of the nasal mucous membrane and penetration of the sella turcica. By adjusting the RF dose to 0.31 +/- 0.09 microgram.kg-1. min-1 and the target concentration of P to 3.48 +/- 1.49 micrograms.ml-1, an increase of HR and MAP above initial values was avoided at this time. Hypotension and bardycardia were treated in eight patients (10.8%) with a vasopressor, in four patients (5.4%) with atropine and in four more patients (5.4%) with a combination of these drugs. Two patients (2.7%) needed antihypertensive therapy. The average time interval between the end of P-TCI and spontaneous breathing was 6 +/- 3 min (median 6 min) and till patients opened their eyes 9 +/- 4 min (median 9 min). After 13 +/- 4 min (median 13 min) the patients became orientated. The average doses of analgetics were 19.5 +/- 19.9 mg piritramide and 1.8 +/- 1.0 g metamizol during the first 12 hours postoperatively. Eight patients (10.8%) did not need any analgetics. We suggest that the combination of RF and P as a "fast track concept" can supplement the repertoire of anaesthetic managements used for transsphenoidal resection of the pituitary gland.

Determination of vibration-related spinal loads by numerical simulation.

OBJECTIVE: Dynamic spinal loads due to human whole body vibrations are extremely difficult to determine experimentally. However, they can be predicted by numerical simulation. This paper presents an approach for the prediction of dynamic spinal loads caused by whole body vibrations, as well as some basic considerations concerning the process of numerical simulation. BACKGROUND: Long-term whole body vibrations have been found to cause health risks for the lumbar spine. As an increasing percentage of the population is exposed to whole body vibrations at work, more and more people have to face the risk of whole body vibrations-related injury. Knowledge about the actual loads in the lumbar spine is essential when spinal loads are to be compared with spinal strength in order to assess the possible health risks caused by whole body vibrations. METHODS: Since an extrapolation of results to unknown data such as spinal loads can only be done using anatomical models of the human body, a simplified finite-element model is presented which is adaptable to body height, body mass, and posture of any specific subject under investigation. The model has been built by reducing a very detailed, nonlinear finite-element model of seated man in its complexity (number of degrees of freedom). Furthermore, the simplified model has been linearised to avoid nonlinear solution procedures. RESULTS: The model has been verified for vertical and horizontal excitation at the seat. Model results have been compared to measurements on subjects. Individual exposure-effect relationships may be predicted by this model, due to the adaptability to a specific subject. Additionally, a new phenomenological method of eliminating the influence of local skin-accelerometer vibrations on vibration measurements on the skin surface is discussed. This method may provide data about bone acceleration that can be used in the process of model verification. CONCLUSIONS: Integral loading measures, such as spinal loads, may be predicted with simplified finite-element models. Quantitative judgements of these loads may be performed for individual conditions. Linearised models may be used for limited ranges of excitation intensities. Energy dissipation should be modeled by discrete dashpot elements instead of proportional damping. RELEVANCE: In order to assess the risk of an injury to the lumbar spine due to whole body vibrations, spinal loads have to be compared with spinal strength. This paper presents the development and verification of a simplified finite-element model of the human body which is based on human anatomy and therefore well-suited to occupational/clinical biomechanics for the prediction of spinal loads.

Design of an active vibration dummy of sitting man.

OBJECTIVE: The determination of vibration transmission through vehicle seats today is still performed with small groups of test subjects. This method suffers from several severe disadvantages, in particular poor repeatability and objectivity due to varying test conditions and limited group sizes. Replacing test persons with a vibration dummy helps to solve this problem. DESIGN: The active vibration dummy simulates the dynamic behaviour of sitting man expressed in terms of the driving point impedance for arbitrary body masses and excitation signals. METHODS: The dummy is realized as a mechatronic system basing on a single degree of freedom setup. A real-time control loop of mass accelerations (and thus acting forces) fits the active dummy to the desired driving point impedance data set. Model and controller parameters are determined by a parameter-identification technique giving meaningful results for arbitrary impedance data sets. RESULTS: The prototype shows excellent agreement with the target data under laboratory conditions. Body mass and excitation level can be varied over the full range of car seat test requirements. RELEVANCE: The determination of vibration transmission through vehicle seats should be possible without human experiments. An active vibration dummy with adjustable vibration behaviour expressed by the vertical driving point impedance covering the entire scope of car seat tests (masses/excitation intensities) is presented. With the dummy, improved seat test procedures could be established, leading to design improvements and therefore to prevention of whole-body vibration injuries.

[Experiences with a combined sciatic and femoral block in surgery of injuries of the lower leg]. / Erfahrungen mit einem kombinierten Ischiadicus- und Femoralisblock bei traumatologischen Eingriffen am Unterschenkel.

Besides various methods of general anaesthesia, regional anaesthetic procedures are well suited for the surgical care of traumatological patients. For operations on patients with lesions of the lower leg, we have been using for 3 years a combination of dorsolateral blockade of the sciatic nerve according to Winnie with a "3 in 1-block". Our experiences with 80 patients show that a complete anaesthesia of the operation field holds for about 100 minutes with a blockade using 1.5% lidocaine with adrenaline. Main indications of this method are operations on lesions of the fibular ligament, leg fractures, ankle joint fractures, removal of osteosynthesis metal and other operations on the leg or foot. Partial or complete failures were registered in 12% of the cases. Severe complications did not occur.

[Operations of vascular brain tumors using pharmacologico-physical metabolic depression and hypotension. Report of experiences in 50 operations]. / Operationen gefässreicher Hirntumoren in pharmakologisch-physikalischer Stoffwechselsekung und Hypotension. Erfahrungsbericht über 50 Operationen.

On the basis of experience gained in operations for cerebral tumours rich in blood vessels in 50 patients the advantages of the combination of a pharmacological-physical reduction of the metabolism and hypotension is dealt with. Nitroprusside sodium hypotension is inferior to this procedure. The experience gained in the different groups is broken down in detail.