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Biomedical subjects

H Fruhstorfer

Publications and source records attributed to H Fruhstorfer.

At least 19 recordsLinked to original sources
PubMed1994

Dose-response relation of ornipressin with regard to vasoconstriction in human skin.

We have studied the vasoconstrictor potency of ornipressin in the skin of 30 volunteers. Subjects received intradermal injections (50 microliters) of five different concentrations of ornipressin (10(-4) - 10(0) u. ml-1 in 0.9% saline) and plain 0.9% saline as a control. Immediately before injection, basal cutaneous blood flow in the test field was enhanced with 1% histamine. Capillary flux was measured by laser Doppler flowmetry and the size of pallor was determined. Ornipressin was effective at 10(-4) u. ml-1 and had its largest constrictor effect at concentrations of 10(-2) and 10(-1) u. ml-1. Larger concentrations were less effective in reducing capillary flux. Interindividually, the most effective concentration varied between 10(-3) and 10(-1) u. ml-1. The size of pallor grew in a dose-dependent manner but 10(0) u. ml-1 always caused reddening in its centre. Capacitance vessels (skin colour) were more sensitive to ornipressin than resistance vessels (capillary flux). The shortest latency of vasoconstriction was obtained with concentrations of 10(-2) and 10(-1) u. ml-1. The results of this study suggest that for haemostasis of the skin a concentration of ornipressin 10(-2) u. ml-1 is useful; this low concentration would reduce total dosage and unwanted side effects.

Adult↗
PubMed1994

Daily variations of functional parameters and density distribution in human blood platelets.

Blood platelets play a critical role in the onset of myocardial infarction, which has been shown to have a circadian rhythmicity with a peak incidence in the morning. In an attempt to correlate platelet parameters with the outcome of cardiovascular diseases, we studied the daily (24-h) variation of the following platelet parameters: distribution pattern of functional heterogeneous platelet subpopulations; serotonin uptake; ketanserin binding; aggregation upon thrombin, serotonin, and ADP stimulation; and platelet count. Furthermore, we analyzed the tryptophan and serotonin concentrations in the blood samples. The percentage of less dense platelets, which represent the subpopulation with the highest preactivation, showed a rhythmicity period of 24 h and an acrophase at 21:18 h. The time course of intermediate and high density platelets was inverse to that of low density platelets. The serotonin uptake exhibited also a rhythmicity with a 24-h period. The acrophase was at 13:50 h. The aggregation curves were inverse to the ketanserin binding curves. The serotonin concentration exhibited a 12-h rhythmicity. The results obtained suggest that (a) changes in platelet activity are reflected by several parameters of platelet function that underlie daily variations; (b) the aggregation curves show a peak in the morning, with an additional peak in the afternoon; and (c) changes in the distribution pattern occur independently from variations in platelet functions like aggregation and serotonin binding.

Adenosine Triphosphate↗
PubMed1991

Automatic scanner for multi-point laser Doppler flux recordings on human skin.

A computer-driven device is described which moves the probes of a laser Doppler flowmeter linearly back and forth over the skin and stops precisely at preselected points to measure capillary perfusion. It offers extended possibilities to record the spatio-temporal flux changes in response to a local stimulus (e.g. injection of a vasoactive substance).

Capillaries↗
PubMed1991

[A simple technique for estimating the level of analgesia in regional anesthesia].

In regional anesthesia the onset of analgesia is usually determined by stimulating the skin with sharp or cold objects: when sensations of sharp pain or cold are lost, all nociceptive afferents are regarded as blocked. Sharp pain and cold are mediated by thin, myelinated axons whereas the majority of nociceptor axons are unmyelinated. In peripheral nerve blocks unmyelinated fibers are blocked first, followed by those mediating sharp pain and cold. In spinal and epidural blocks the levels of anesthesia to sharp pain and cold correspond within 1-2 segments. Although pinprick seems to be a simple test for analgesia, it involves the risk of infection and is disliked by the patient. As the stimulus is spatially discontinuous, coarse testing may simulate analgesia. An ideal stimulus for testing analgesia should be noninvasive, give distinct sensations, not frighten the patient, and allow spatially continuous examination of larger skin areas. A stimulus that meets these conditions is cold applied to the skin by a metal roller (Fig. 1). If the roller is kept at room temperature (20 degrees-24 degrees C), it gives a strong cold sensation when it is slowly rolled (5-10 cm/s) over the warm skin (usually 30 degrees-35 degrees C on the trunk). With this noninvasive device, the levels of anesthesia to cold can be determined rapidly, with high precision, and without frightening the patient.

Analgesia↗
PubMed1990

[Cutaneous blood flow following subcutaneous infiltration of lidocaine with and without the addition of adrenaline or ornipressin].

The addition of ornipressin to local anesthetics increases the duration of regional anesthesia. A dose of 0.1 unit/ml produces an increase in nerve block duration comparable to adrenaline 5 micrograms/ml. In order to suppress intraoperative bleeding higher concentrations of ornipressin have been used in infiltration anesthesia. This study was designed to examine whether an increase in ornipressin concentration above 0.1 unit/ml causes a further reduction in cutaneous blood flow. Twelve volunteers took part in the study. They received intracutaneous infiltrations of 4 ml lidocaine 0.5% in the volar aspects of both forearms (Fig. 1). The solution was either plain (= Lido) or contained adrenaline 5 micrograms/ml (Lido + A), or ornipressin 0.1 unit/ml (Lido + P1) or 0.2 unit/ml (Lido + P2). Blood flow was measured with a laser Doppler flowmeter; before the infiltration the skin was locally heated to 40 degrees C in order to obtain maximal perfusion (Flow 100); this temperature was maintained throughout the measuring period. The minimal flow after infiltration was calculated as a percentage of Flow 100. Lido caused a significant decrease in flow to 59 +/- 25% (M +/- SD). Lido + A, Lido + P1 and Lido + P2 caused further significant flow reductions, to 19 +/- 21%, 23 +/- 16% and 26 +/- 23%, respectively (Figs. 3, 4). The latency of maximal flow reduction did not differ between the four solutions (Fig. 5). The results show that in infiltration anesthesia an increase in ornipressin concentration above 0.1 unit/ml does not improve superficial vasoconstriction.

Anesthetics, Local↗
PubMed1988

Effects of daytime noise load on the sleep-wake cycle and endocrine patterns in man: I. 24 hours neurophysiological data.

This study examines the influence of daytime noise load on the spontaneous EEG activity during wakefulness and sleep. Twelve healthy male subjects participated in two experimental series, each consisting of three consecutive nights and the two days in between. EEG, EOG, EMG, ECG and respiration were continuously recorded. During one series from 9:00 to 21:00 h the subjects were exposed to 85 dB(A) industrial noise. Direct effects of the noise exposure were a slight blockade of the alpha and theta activity; towards the evening, when self-estimated tiredness was high, increased alpha and beta power were found (p less than .01). Aftereffects on subsequent undisturbed night sleep were a reduction in REM sleep (p less than .001), shortened sleep cycles (p less than .01) and an increase in slow wave sleep during the 2nd sleep cycle (p less than .05). These results are interpreted as signs of strained wakefulness and intensified fatigue, as disturbance of sleep processes and as an intensified need for recovery.

Adult↗
PubMed1985

Daytime noise stress and subsequent night sleep: interference with sleep patterns, endocrine and neurocrine functions.

The effects of strong daytime noise stress on subsequent undisturbed night sleep were studied in six male volunteers. They slept for seven consecutive nights in the laboratory, two nights being preceded by an 8 h exposure to 83 dB (A) pink noise. Continuously during all nights EEG, EOG, EMG, ECG and respiration were recorded. Additionally, during five nights, blood samples were taken every 30 min by an indwelling venous catheter for the determination of ACTH, hGH, PRL, TRP, 5-HT and 5-HIAA. After daytime noise load, increased sleep stage 4 stability, partly elevated hGH and PRL levels and decreased levels of the metabolites of the serotonergic system were found. This result may be explained by the assumption that high daytime noise stress is an additional load for the CNS which demands an intensification of recovery processes during the sleep of the subsequent night.

Adrenocorticotropic Hormone↗
PubMed1985

[Addition of muscle relaxants to intravenous regional anesthesia].

Nine volunteers received two intravenous regional anaesthetics in the right arm. The first anaesthetic was performed with plain 0.25% lignocaine (dose 1 ml/kg body weight), the second with the same volume of lignocaine, with the addition of 0.5 mg pancuronium-Bromide. Latency for onset of the following was measured in both groups: 1. analgesia, 2. cold sensation, 3. warm sensation, 4. touch, 5. motor blockade. As expected, the addition of pancuronium had no influence on sensory blockade, however, motor block was significantly stronger, faster in onset, and longer in duration. Significant systemic side effects after pancuronium were not observed. No pancuronium was found in flame photometry plasma studies. On the basis of these investigations, one can recommend, for I.V.R.A., a relatively large volume of dilute local anaesthetic solution and, to achieve better muscle relaxation, the addition of 0.5 mg of pancuronium.

Adult↗
PubMed1984

Daytime noise and subsequent night sleep in man.

The effects of daytime noise on recovery processes during subsequent undisturbed night sleep were studied in six healthy men (21-27 years), exposed to 80 dB (A) pink noise 8 h per day for 2 days. Sleep EEG, ECG, and respiration were recorded in the laboratory for five consecutive nights: two baseline nights, two nights following noise stimulation, and again one baseline night. Additionally questionnaire data were collected, reflecting a subjective impairment of the recovery function of sleep after noise exposure. EEG sleep data of the first post-noise night showed an increase in slow wave sleep with a simultaneous decrease in stage 2 sleep. During the second post-noise night these changes were less prominent. Three subjects additionally showed an instability in the sleep course coinciding with elevated heart and respiration rates. However, altogether the autonomic parameters were not clearly affected by the noise exposure. The findings support the assumption that strong daytime noise may interfere with subsequent sleep processes.

Adult↗
PubMed1978

[Comparative studies of the local anaesthetic action of carticaine 1% and mepivacaine 1% (author's transl)].

The actions of carticaine 1% and mepivacaine 1% in peripheral nerve block were investigated in double-blind study. Bilateral ulnar nerve blocks were performed in 14 healthy subjects (age range 20-30 years), and latency, duration, and intensity of anaesthesia were quantitatively determined. There were no differences in latency of nerve block, but a significant difference in the duration of effect: Mepivacaine acted for nearly twice as long as Carticaine. In addition, several incomplete blocks were noted with Carticaine. On the basis of these results mepivacaine is preferred in peripheral nerve block because of its longer and more reliable action.

Adult↗
PubMed1976

Method for quantitative estimation of thermal thresholds in patients.

A quantitative method for the examination of thermal sensibility was applied in 26 normal subjects and in patients with various neurological disorders. The stimulation technique resembled Békésy audiometry: the patient reversed the direction of the temperature change of a thermode whenever warm, cold, or thermal pain thresholds were reached. The resulting temperature curve enables a quantitative description of the subject's thermal sensibility and of the degree of impairment displayed by neurological patients.

Abdomen↗
PubMed1975

A comparative study between etidocaine and bupivacaine in ulnar nerve block.

The long-acting local anaesthetics bupivacaine and etidocaine were compared in a double-blind study using ulnar nerve block. Eleven volunteers took part in the study. Solutions used were: bupivacaine 0.25% and 0.5% and etidocaine 0.5% and 1 %. All solutions contained adrenaline 5 mug/ml. The time of onset and duration of analgesia and motor block, degree of motor block, and changes in skin temperature were investigated. The results did not show any differences in the duration of sensory of motor block. Differences were seen in the degree of motor block in favour of etidocaine. The sympathetic block seemed to be more intense and of longer duration with bupivacaine. Etidocaine had a shorter time of onset in all nerve fibres.

Acetanilides↗
PubMed1975

Brachial plexus blockade for evaluation of local anaesthetic agents.

Brachial plexus block (axillary approach) has been compared with ulnar nerve block for the evaluation of local anaesthetic drugs. Duration of analgesia is the same in both techniques with the same drugs. Following axillary nerve block the median, ulnar and radial nerves are blocked for a different time. The onset of motor block is faster following axillary nerve block, according to muscle power, but not according to action potentials in the e.m.g. Once all the nerves are blocked, no differences exist for the duration of muscle paralysis. The rate of techinical failure is higher with brachial plexus blocks compared with single nerve blocks. Larger amounts of local anaesthetic solutions are necessary for plexus blockade and this may cause toxic effects. The volunteer's comfort is less after plexus block because of more widespread paralysis. Therefore, ulnar nerve block and extradural block are in many respects the most suitable techniques for evaluation of new local anaesthetic agents.

Action Potentials↗
PubMed1975

[Axillary plexus block with long-acting local anaesthetics (a comparative study of etidocaine and bupivacaine) (author's transl)].

Brachial and axillary plexus blockade was carried out on volunteers using a mixture of etidocaine 1% with adrenaline, and bupivacine 0,5% with adrenaline. Both drugs are long-acting local anaesthetics. No difference has been established with regard to duration of analgesia and motor nerve block. Blockade of sympathetic nerve fibres lasts significantly longer with bupivacaine than with etidocaine. With the latter motor blockade seems to be more strongly influenced and significantly outlasts sensory sympathetic nerve block. The results and findings of other authors are discussed, and whether the different behaviour of the 2 long acting local anaesthetics in this context implies a different affinity of the drugs to the different types of nerves.

Acetanilides↗