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Biomedical subjects

R Wymann

Publications and source records attributed to R Wymann.

8 recordsLinked to original sources
PubMed2001

Modeling and closed-loop control of hypnosis by means of bispectral index (BIS) with isoflurane.

A model-based closed-loop control system is presented to regulate hypnosis with the volatile anesthetic isoflurane. Hypnosis is assessed by means of the bispectral index (BIS), a processed parameter derived from the electroencephalogram. Isoflurane is administered through a closed-circuit respiratory system. The model for control was identified on a population of 20 healthy volunteers. It consists of three parts: a model for the respiratory system, a pharmacokinetic model and a pharmacodynamic model to predict BIS at the effect compartment. A cascaded internal model controller is employed. The master controller compares the actual BIS and the reference value set by the anesthesiologist and provides expired isoflurane concentration references to the slave controller. The slave controller maneuvers the fresh gas anesthetic concentration entering the respiratory system. The controller is designed to adapt to different respiratory conditions. Anti-windup measures protect against performance degradation in the event of saturation of the input signal. Fault detection schemes in the controller cope with BIS and expired concentration measurement artifacts. The results of clinical studies on humans are presented.

Adult↗
PubMed1993

[Incidence of drug side effects by symptoms and syndromes. From the experiences of the Comprehensive Hospital Drug Monitoring and the Swiss Drug Side Effect Center. As an example: allergic and pseudo-allergic reactions with mild analgesics and NSAID].

From 1974 to 1989, 37,392 patients were admitted to the divisions of general internal medicine of the CHDM hospitals. 19,082 of them were treated with a minor analgesic or an NSAID. In 95 of the exposed patients, an allergic or a pseudoallergic reaction to one or two of these drugs was observed. From 1981 to 1990, general practitioners, hospitals and the pharmaceutical industry reported to SANZ 158 individual cases with comparable reactions to 175 exposures of the same kind. Of the 15 different syndromes and symptoms registered in both institutions, most were reactions of the skin, mainly the usual maculopapular exanthemas (rash), urticaria and angioedema. In the CHDM, allergic or pseudoallergic reactions were observed in 0.23% of patients exposed to minor analgesics (including ASA preparations on a daily dose up to 1.0 g and pyrazolones, mainly metamizole, propyphenazone) and in 0.81% of patients exposed to NSAIDs (including the pyrazolone oxyphenbutazone). In the experience of the Comprehensive Hospital Drug Monitoring in Berne and St. Gallen (CHDM) and the Spontaneous Adverse Drug Reactions Center of Switzerland (SANZ).

Adverse Drug Reaction Reporting Systems↗
PubMed1990

[Acute severe dyspnea as a side effect of drugs. Report from the CHDM (Comprehensive Hospital Drug Monitoring)].

This "syndrome" has been observed in 4 of 23,935 in-patients registered in the years 1974-1987 in the Comprehensive Hospital Drug Monitoring (Bern/St. Gallen), with 6 reactions. Signs of an attack of bronchial asthma, laryngeal or pulmonary edema or a (heart-)circulatory event were not observed. Each patient was cyanotic and 3 had the feeling of impending death. The eliciting drugs were penicillin-G (twice) and cefazolin (once), given i.v.; iron dextran i.m. (once); pitressin tannate i.m. (once) and dicobalt edetate (Kelocyanor) i.v.(once). In each case the reaction started during or shortly after injection of the drug; the duration of the reaction in 5 of these events was 20-80 minutes. The pathomechanism could be a special form of anaphylactic reaction with acute pulmonary hypertension, comparable to IgE-induced anaphylaxis in the rabbit or aggregate anaphylaxis in the monkey or the dog. Further observations are needed for more detailed study.

Acute Disease↗
PubMed1990

Time pattern of allergic reactions to drugs.

Generalized, allergic reactions to drugs show time patterns different from those based on pharmacological concepts. We distinguish three types of reactions: acute reactions (reaction time (RT): 0-60 minutes), subacute reactions (RT: 1-24 hours) and reactions of the latent type (RT: 1 day to several weeks). In this study, allergic reactions in the strict sense are supplemented by reactions considered to be based on intolerance or idiosyncrasy to aspirin, pyrazolones, paracetamol, NSAIDs, quinidine, iodine-containing contrast media and some as yet not understood reactions to local anaesthetics. Out of a total of 23,935 drug monitoring patients with 32,317 hospitalizations in the clinical divisions of internal medicine at three Swiss hospitals during the 1974-1987 period, 951 patients with 1,040 probably or definitely drug-related events of the selected type were recorded. Ultimately, 287 patients with 310 adverse drug reactions (ADRs) fulfilled our selection criteria and were classified into six groups of syndromes (Table 1). (Of the reactions described as maculopapular rash, unspecified rash and special exanthema, only the 159 reactions from the 1985-1987 period out of a total of 889 reactions of this type observed during the whole study period were included in our secondary evaluation.) The total number of 310 reactions (100%) showed the following RT distribution: 36 (11.6%) were of the acute type, 13 (4.2%) of the latent type, 12 (3.9%) could be interpreted as two distinct possible types of reaction to different drugs, and for 3 (1.0%) reactions, the type of reaction was indeterminable. The majority of reactions, 246 (79.4%), were of the subacute type starting within 24 hours of the last drug exposure. Among the 36 reactions of the acute type, 7 events of acute severe dyspnoea were observed which seemed to be as life-threatening as anaphylactic or anaphylactoid shock. These hospital-epidemiological data are of interest for focusing basic research and developing further principles of drug safety.

Anti-Bacterial Agents↗
PubMed1987

[Skin side effects of non-steroidal anti-inflammatory analgesics and so-called minor analgesics. Report from the Berne Comprehensive Hospital Monitor].

9118 of 19,653 inpatients of two internal medicine divisions were treated with analgesics and nonsteroidal antiinflammatory drugs including minor analgesics (NSAID). In the first part of the study all generalized skin reactions (gsr) considered to be probably or definitely due to a drug were evaluated clinically. In 23 out of 91 patients with a drug induced skin reaction, this was judged to be mainly related to an NSAID drug rather than any other drug (= 0.3% of patients exposed to an NSAID). The 26 reactions of the 23 patients were as follows: 15 maculo-papular exanthemas, 6 urticarias, 2 angioedema, 2 serum sickness syndromes and 1 erythema nodosum. In the second part we did statistical calculations only on the basis of the time/exposure relationship to ascertain the rate of gsr with chemotherapeutics and antibiotics (group B), with NSAID including minor analgesics (group A) and with all other drugs. 10.8% occurred with B, 1.8% with A without B and 0.9% without A and without B. The difference between 1.8% (A without B) and 0.9% (neither A nor B) is significant (p less than 0.05).

Analgesics↗