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J Schüttler

Publications and source records attributed to J Schüttler.

At least 19 recordsLinked to original sources
PubMed2007

Teletherapeutic drug administration by long distance closed-loop control of propofol.

BACKGROUND: The objective of this pilot study was to investigate the feasibility of an EEG-controlled closed-loop administration of propofol over a long distance of about 200 km. METHODS: We performed a teletherapeutic propofol infusion during total intravenous anaesthesia with propofol in 11 patients undergoing general surgery. The teletherapeutic system consisted of a computer at the patient site in Munich and a computer at the control site in Erlangen, which were connected via the internet through a virtual private network. The patient's EEG signal was sent to the control site computer, where the median frequency (MEF) of the EEG power spectrum was calculated. The propofol infusion, determined by a model-based adaptive feedback algorithm to maintain a MEF of 1.5 to 2 Hz, was sent to the patient site computer connected to the infusion pump. The quality of the control was assessed by the performance error defined as the percentage deviation of the measured MEF from the set point and the necessity of interventions by the anaesthetist at the patient site. RESULTS: During closed-loop administration of propofol [83 (52) min] the median performance error of the system was - 4.6 (4.4)% and the median absolute performance error was 18.8 (5.7)%. From a total number of 10 905 transmitted EEG epochs, there were five epochs with transmission errors, without further consequences for drug control. In one patient, teletherapy was stopped because the internet connection was interrupted. CONCLUSIONS: Teletherapeutic drug administration could be realized over a longer distance. Further studies have to investigate the practicability and safety of teletherapeutic drug control in anaesthesia.

Adolescent↗
PubMed2007

[Patient-controlled analgesia (PCA) in outpatients with cancer pain. Analysis of 1,692 treatment days].

INTRODUCTION: In the home-care setting, cancer pain patients in need of parenteral analgesia have to be switched to patient-controlled analgesia using portable pumps. But there is a paucity on data on the logistic requirements or the success rate of such a cost-intensive therapy performed by specialized home-care services. METHODS: In a retrospective study we analyzed data on care intensity, logistics and outcome of 46 consecutive palliative cancer patients with patient-controlled analgesia (PCA) in a home-care setting. RESULTS: On days 1, 2, and 3 of PCA the switch to parenteral analgesia resulted in a significant increase of the median daily opioid dose in comparison to the dose just prior to PCA. Concurrently, pain scores were significantly reduced. The median duration of PCA was 25 days (range 2-189 days). On average, each patient was seen by the home-care team every 7.4 days. The median duration of the home visits was 60 min (range, 10-190 min). Of the visits 20% were unscheduled, most of these visits being due to problems regarding analgesia. Most patients died at home. Insufficient analgesia required prefinal hospitalization in only a single case. CONCLUSION: If the indications are correct, intravenous PCA for palliative cancer pain patients results in higher opioid consumption and better pain control. Home-care PCA requires a lot of human and financial resources, but pain-related hospitalization can be prevented.

Adolescent↗
PubMed2006

[Pharmacodynamics of two different propofol formulations].

BACKGROUND: Propofol is nowadays available in various lipid formulations. We compared two different propofol formulations with respect to pharmacodynamics, using the EEG and clinical signs. MATERIALS AND METHODS: Ten volunteers received Diprivan 1% and Propofol 1% MCT Fresenius as a computer controlled infusion with increasing propofol target concentrations. A sigmoid E(max) model with effect compartment was estimated for the median frequency of the EEG power spectrum, based on measured arterial propofol plasma concentrations. Clinical pharmacodynamics were assessed by reaction on acoustic stimuli, eyelid reflex and corneal reflex. RESULTS: The drugs did not differ in pharmacodynamics with respect to EEG (EC(50) 2.1+/-0.6 for Diprivan and 2.1+/-0.5 microg/ml for Propofol Fresenius) and clinical signs. The pharmacodynamic model was characterized by a steep concentration effect relationship and a distinct hysteresis between propofol plasma concentration and effect (k(e0) 0.12+/-0.04 and 0.12+/-0.5 min(-1)). CONCLUSIONS: The investigated lipid formulations have no influence on the pharmacodynamics of propofol.

Acoustic Stimulation↗
PubMed2006

[Equipment of a land-based emergency medical service in Bavaria: a questionnaire].

BACKGROUND: Currently valid DIN regulations concerning the emergency equipment in physician-staffed rescue vehicles are not well defined for every single item. This leads to variations in the equipment in different ambulances. The aim of this study was to demonstrate the differences with some exemplary equipment purchases. METHODS: All 218 physician-staffed rescue vehicles in Bavaria received a questionnaire asking for current emergency medical equipment and planned items. RESULTS: A reply was received from 177 of the 218 bases (81%). The main results were that 88% of all bases had a 12-lead ECG, a portable emergency ventilator was available at 93% of all bases, 77% had alternative airway management devices (set for emergency coniotomy 71%, laryngeal mask 26%), expiratory CO(2 )measuring was available at 32% and 31 bases (18%) had fibrinolytic drugs in the emergency vehicles. CONCLUSIONS: There are vast differences among the emergency physician-staffed ambulances concerning the equipment which means that medical treatment according to current recommendations is not always possible at all bases.

Adult↗
PubMed2005

Concurrent recording of AEP, SSEP and EEG parameters during anaesthesia: a factor analysis.

BACKGROUND: Spontaneous EEG, mid-latency auditory evoked potentials (AEP) and somatosensory evoked potentials (SSEP) have been used to monitor anaesthesia. This poses the question as to whether or not EEG, AEP and SSEP vary in parallel with varying conditions during surgical anaesthesia. METHODS: A total of 81 variables (31 EEG, 22 SSEP, 28 AEP) were simultaneously recorded in 48 surgical patients during anaesthesia. A total of 307 cases of the 81 variables in stable anaesthetic states were recorded. A factor analysis was performed for this data set. RESULTS: Sixteen variables were excluded because of multicollinearity. We extracted 13 factors with eigenvalues >1, representing 78.3% of the total variance, from the remaining 65 x 307 matrix. The first three factors represented 12%, 11% and 10% of the total variance. Factor 1 had only significant loadings from EEG variables, factor 2 only significant loadings from AEP variables and factor 3 only significant loadings from SSEP variables. CONCLUSION: EEG, AEP and SSEP measure different aspects of neural processing during anaesthesia. This gives rise to the hypothesis that simultaneous monitoring of these quantities may give additional information compared with the monitoring of each quantity alone.

Anesthesia, General↗
PubMed2004

["The intensive care simulator": a new teaching-concept to train severe sepsis management].

BACKGROUND AND OBJECTIVE: In addition to basic research and development of new therapeutic strategies, the education of health care professionals who manage sepsis patients is an important step to decrease the high mortality of severe sepsis. Patient simulators are increasingly used for teaching in anaesthesia. A training program in sepsis management was developed, using a full-scale anaesthesia simulator including the setting of a modern intensive care unit, and its results were evaluated by means of a questionnaire. METHODS: The simulator is controlled from a separate room using a controlling computer provided with physiological models and pharmacokinetic as well as pharmacodynamic patterns of substances commonly used in anaesthesia and intensive care. An important element of the training program is the subsequent debriefing with different modules, according to the individual deficits and needs of the participants detected during simulation. RESULTS: From September 2002 to July 2004 82 physicians participated in the training program. 4 weeks after the training 52 % of the participants stated that they had changed their treatment behaviour due to the training content. They assessed the interactive simulator workshop semiquantitatively on a scale from 1 ("absolutely correct") to 7 ("not correct at all") as follows: Sepsis simulation training (SST) improves identification (mean+/-SD) (2.3 +/- 1.3) and treatment (2.5 +/- 1.2) of patients with severe sepsis, and SST including true-life scenarios is more appropriate than traditional lectures (1.5 +/- 0.7). CONCLUSION: The presented SST could be an effective way to train intensive care specialists in severe sepsis management.

Anesthesia↗
PubMed2004

[Simulator-based modular human factor training in anesthesiology. Concept and results of the module "Communication and Team Cooperation"].

BACKGROUND: Human factors (HF) play a major role in crisis development and management and simulator training can help to train HF aspects. We developed a modular training concept with psychological intensive briefing. The aim of the study was to see whether learning and transfer in the treatment group (TG) with the module "communication and team-cooperation" differed from that in the control group (CG) without psychological briefing ("anaesthesia crisis resource management type course"). METHODS: A total of 34 residents (TG: n=20, CG: n=14) managed 1 out of 3 scenarios and communication patterns and management were evaluated using video recordings. A questionnaire was answered at the end of the course and 2 months later participants were asked for lessons learnt and behavioral changes. RESULTS: Good communication and medical management showed a significant correlation (r=0.57, p=0.001). The TG showed greater initiative ( p=0.001) and came more often in conflict with the surgeon ( p=0.06). The TG also reported more behavioral changes than the CG 2 months later. The reported benefit of the simulation was training for rare events in the CG, whereas in the TG it was issues of communication and cooperation ( p=0.001). CONCLUSIONS: A training concept with psychological intensive briefing may enhance the transfer of HF aspects more than classical ACRM.

Anesthesia↗
PubMed2004

[Accuracy of target-controlled infusion (TCI) with 2 different propofol formulations].

BACKGROUND: Target-controlled infusion (TCI) of propofol was initially realized as a device for prefilled syringes (Diprifusor). New TCI systems can be used with any propofol formulation. We compared two different propofol formulations with respect to accuracy of TCI and pharmacokinetics. MATERIALS AND METHODS: A total of 10 volunteers received Diprivan 1% and Propofol 1% MCT Fresenius as TCI using the pharmacokinetic model of the Diprifusor. The prediction error was determined from measured arterial concentrations. A three-compartment model was fitted to the concentration data. RESULTS: The median prediction error and the median absolute prediction error were -1.4% and 23.3% for Diprivan, and -5.9% and 17.8% for Propofol Fresenius. The drugs did not differ in pharmacokinetics but showed a smaller central volume of distribution than used for infusion control. CONCLUSIONS: The pharmacokinetic model of Diprifusor can also be used for TCI of Propofol Fresenius. The large volume of distribution in this model may cause an overshoot in concentration.

Adult↗
PubMed2003

Testing and modelling the interaction of alfentanil and propofol on the EEG.

BACKGROUND AND OBJECTIVE: For total intravenous anaesthesia an opioid is often combined with a hypnotic. A supra-additive interaction has been reported for clinical signs such as loss of consciousness or loss of the eyelash reflex. This study investigated the type of interaction of alfentanil and propofol on the electroencephalogram. METHODS: Twenty patients scheduled for abdominal surgery were enrolled in the study. Anaesthesia was induced and maintained with alfentanil and propofol. Each patient received a target-controlled infusion of alfentanil. Three target concentrations of 150, 225 and 300 ng mL(-1) were applied to each patient in random order. Propofol was added to the alfentanil infusion by a feedback system. The set point was the range of 1.5-2.5 Hz median frequency of the electroencephalogram. Four arterial blood samples were taken within the last 20 min of each period. The mean drug concentrations were used to determine the type of interaction and an isobole was estimated by fitting Bernstein spline functions to the data. RESULTS: In 17 patients, all three alfentanil target concentrations could be administered. The test for supra-additivity as well as the isobole construction resulted in an additive type of interaction. The line of additivity cA/cA0 + cP/cP0 = 1 was best fitted for the values (standard deviation) cA0 = 1240 (51)ng mL(-1) and cP0 = 5.21 (0.36) microg mL(-1). CONCLUSIONS: The type of interaction between alfentanil and propofol on the electroencephalogram in the investigated dose range is additive. This gives the freedom and need to select the appropriate dosing ratio of alfentanil and propofol by other considerations.

Abdomen↗
PubMed2003

Modelling the pharmacodynamic interaction between remifentanil and propofol by EEG-controlled dosing.

BACKGROUND AND OBJECTIVE: Knowledge of the pharmacodynamic interaction between remifentanil and propofol is important to permit optimal dosage strategies. We studied this pharmacodynamic interaction using the median power frequency of the processed electroencephalogram as a control parameter for feedback-controlled dosing of propofol. METHODS: Twenty-one patients were given total intravenous anaesthesia with remifentanil and propofol. During three target-controlled infusion regimens, the target concentrations of remifentanil (5, 10, 15 ng mL(-1)) and propofol dosing were automatically adjusted to keep the median power frequency in the range 2 +/- 0.5 Hz. In each patient and during each remifentanil target concentration, four arterial propofol/remifentanil concentration pairs were measured. The type of interaction was tested using the relative distance from the line of additivity and the isobole was modelled using Bernstein splines. RESULTS: The results from 13 patients were used for data analysis. The measured remifentanil concentrations during the three targets were (mean +/- SD): 3.6 +/- 0.9, 8.1 +/- 2.5 and 12.4 +/- 2.8 ng mL(-1). The corresponding propofol concentrations were 2.64 +/- 0.86, 2.13 +/- 0.58 and 2.09 +/- 0.58 microg mL(-1). The data were best described with an additive type of interaction and the isobole was estimated using: ((c)Remifentanil/64.2 ng mL(-1)) + ((c)Propofol/2.61 microg mL(-1)) = 1. CONCLUSIONS: Within the studied concentration range, remifentanil and propofol showed an additive type of pharmacodynamic interaction on the electroencephalogram.

Adult↗
PubMed2001

[First results in an animal model on stents sheathed with a polytetrafluoroethylene membrane].

OBJECTIVES: Mechanisms of restenosis after coronary stent implantation include marked intimal proliferation as well as vascular tissue protrusion through the meshes. Thus, stent sheathed with membranes may be an alternative to improve the long-term outcome. METHODS: Seventeen cylindric serpentine shaped 316L stainless steel stents (nominal diameter 3.0 mm, length 15 mm) lined and covered by a polytetrafluoroethylene (PTFE) membrane and 10 unsheathed devices were implanted into the iliac arteries of 14 New Zealand White Rabbits for an observation period of 1 - 10, 11 - 20, and 21 - 30 weeks. After sacrificing the animals, specimens were harvested, fixed in formalin, processed in paraffin, serially sliced into 5 microm thick preparations, and stained (hematoxylin & eosin, elastica von Gieson). RESULTS: The polytetrafluoroethylene membrane stents increased the vascular lumen significantly (p < 0.04) to 1185.3 - 1620.4 microm compared with the native segments (655.6 +/- 268.8 microm). In the stainless steel stents the lumen decreased from 1873.1 microm to 719.1 microm. None of the devices penetrated the internal elastic membrane. There was no inflammatory vascular reaction. Compared to the native segments, the amount of elastic fibres was slightly less (native: 8.9 %, PTFE: 2.3 - 3.5 %, without PTFE: 1.9 - 5.5 %) whereas the collagen fibres increased marginally (native: 5.1 %, PTFE: 6 - 6.9 %, without PTFE: 6.4 - 8.4 %). CONCLUSIONS: In the rabbit iliac artery, stents sheathed with a microporous polytetrafluoroethylene membrane showed good tissue compatibility with no restenosis. These results warrant clinical trials.

Angioplasty, Balloon, Coronary↗
PubMed2001

200 years of nitrous oxide (laughing gas)--and the end of an era?

The history of nitrous oxide is more than 200 years old and its clinical use as anaesthetic is more than 150 years old. The symposium discussed the question whether nitrous oxide should maintain its traditional role as a component of the anaesthetic breathing gas in everdays anaesthetic procedure or whether there are indications not to continue the regular use of nitrous oxide. As a matter of fact the continued use of nitrous oxide will not change its clinical pharmacology and one may argue that every year of additional experience with this drug is likely to increase the safety of its application. However, one has steadily to judge the risks of this drug against its alternatives and these have changed dramatically over the past decades. The new anaesthesia machines allow the combination of oxygen and air as breathing gas, there are new inhalational agents (e. g. desflurane, xenon) as controllable as nitrous oxide and new i. v. agents. As a conclusion of these developments the Department of Anaesthesiology at the Universität Erlangen-Nürnberg has decided to cease the traditional use of nitrous oxide.

Anesthetics, Inhalation↗
PubMed2001

Stereoselective pharmacokinetics of ketamine: R(-)-ketamine inhibits the elimination of S(+)-ketamine.

OBJECTIVE: We investigated the pharmacokinetics of ketamine with special regard to enantiomer-specific differences. METHODS: Ten healthy young male volunteers (mean age, 28 +/- 4 years; mean weight, 79 +/- 11 kg) received racemic ketamine and S(+)-ketamine in a randomized double-blind crossover study. Drugs were administered by a computer-controlled device. Two infusion cycles with linearly increasing targets [slope, 0.1 microg x ml(-1) x min(-1) for S(+)-ketamine and 0.2 microg x ml(-1) x min(-1) for racemic ketamine] were administered. Concentrations of the ketamine enantiomers were determined from arterial blood, and pharmacokinetic parameters were estimated with a 2- and 3-compartment model. RESULTS: The total doses needed to reach defined end points were 271 +/- 80 mg and 409 +/- 75 mg for S(+)-ketamine and racemic ketamine, respectively (P <.05). S(+)-ketamine showed a significantly higher clearance (26.3 +/- 3.5 ml x kg(-1) x min(-1)) compared with racemic ketamine (14.8 +/- 1.7 ml x kg(-1) x min(-1); P <.05) and R(-)-ketamine (13.8 +/- 1.3 ml x kg(-1) x min(-1); P <.05). Furthermore, the clearance of the S (+)-ketamine was smaller in the racemate (18.5 +/- 0.7 ml x kg(-1) x min(-1); P <.05) than for the pure isomer. CONCLUSIONS: These results demonstrate that R(-)-ketamine inhibits the elimination of S(+)-ketamine.

Adult↗
PubMed2001

A new model of electrically evoked pain and hyperalgesia in human skin: the effects of intravenous alfentanil, S(+)-ketamine, and lidocaine.

BACKGROUND: The authors used the analgesics alfentanil, S(+)-ketamine, and systemic lidocaine to examine a new human model of experimental pain and hyperalgesia. METHODS: Transcutaneous electrical stimulation at a high current density (5 Hz, 67.5+/-6.6 mA) was used to provoke acute pain (numeric rating scale, 5 of 10), stable areas of secondary mechanical hyperalgesia to pin prick (43.6+/-32.1 cm2), and light touch (27.5+/-16.2 cm2) for 2 h. Alfentanil, S(+)-ketamine, and lidocaine were applied for 20 min in a double-blind, placebo-controlled, crossover design in 12 subjects using target controlled infusions. RESULTS: In the placebo session, pain ratings and areas of hyperalgesia were stable during the stimulation period, which facilitated the assessment of analgesic effects. Alfentanil effectively inhibited electrically evoked pain and reduced pin prick hyperalgesia and allodynia during its infusion. S(+)-ketamine-induced inhibition of secondary hyperalgesia was more pronounced and lasted for the whole experimental protocol. Therapeutic levels of systemic lidocaine showed only marginal analgesic effects, but lasting antihyperalgesic effects. CONCLUSIONS: A new model of electrically induced pain and hyperalgesia was established, which enabled assessment of the time course of analgesic and antihyperalgesic effects with high temporal resolution and minimum tissue damage and which was further validated by use of common intravenous anesthetics.

Adult↗
PubMed2000

Postoperative pain control following remifentanil-based anaesthesia for major abdominal surgery.

Eighty patients undergoing major abdominal surgery using remifentanil-based anaesthesia were randomly allocated in a double-blind manner to receive an intravenous bolus of fentanyl, buprenorphine, morphine or piritramide 20 min before the end of surgery. A reduced dose was administered postoperatively when patients reported moderate pain. Subsequent analgesia was provided by patient-controlled analgesia (PCA). The mean time from the end of anaesthesia to spontaneous respiration was 9 +/- 5 min. At first pain assessment, 63% of patients reported no or mild pain; 80% of patients required the second opioid bolus, those receiving piritramide needed the bolus significantly later than patients receiving buprenorphine or fentanyl. First PCA requirement also occurred significantly later in the piritramide group. This technique provided effective postoperative pain relief and transition to routine PCA and did not compromise recovery.

Abdomen↗
PubMed2000

Population pharmacokinetics of propofol: a multicenter study.

BACKGROUND: Target-controlled infusion is an increasingly common type of administration for propofol. This method requires accurate knowledge of pharmacokinetics, including the effects of age and weight. The authors performed a multicenter population analysis to quantitate the effects of covariates. METHODS: The authors analyzed 4,112 samples of 270 individuals (150 men, 120 women, aged 2-88 yr, weighing 12-100 kg). Population pharmacokinetic modeling was performed using NONMEM (NONMEM Project Group, University of California, San Francisco, CA). Inter- and intraindividual variability was estimated for clearances and volumes. The effects of age, weight, type of administration and sampling site were investigated. RESULTS: The pharmacokinetics of propofol were best described by a three-compartment model. Weight was found to be a significant covariate for elimination clearance, the two intercompartmental clearances, and the volumes of the central compartment, the shallow peripheral compartment, and the deep peripheral compartment; power functions with exponents smaller than 1 yielded the best results. The estimates of these parameters for a 70-kg adult were 1.44 l/min, 2.25 l/min, 0.92 l/min, 9.3 l, 44.2 l, and 266 l, respectively. For patients older than 60 yr the elimination clearance decreased linearly. The volume of the central compartment decreased with age. For children, all parameters were increased when normalized to body weight. Venous data showed a decreased elimination clearance; bolus data were characterized by increases in the volumes of the central and shallow peripheral compartments and in the rapid distribution clearance (Cl2) and a decrease in the slow distribution clearance (Cl3). CONCLUSIONS: Pharmacokinetics of propofol can be well described by a three-compartment model. Inclusion of age and weight as covariates significantly improved the model. Adjusting pharmacokinetics to the individual patient should improve the precision of target-controlled infusion and may help to broaden the field of application for target-controlled infusion systems.

Adolescent↗