Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Automatism”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1991

Anesthetics and automaticity in latent pacemaker fibers: I. Effects of halothane, enflurane, and isoflurane on automaticity and recovery of automaticity from overdrive suppression in Purkinje fibers derived from canine hearts.

Knowledge of arrhythmic or antiarrhythmic actions of anesthetics on automaticity of latent pacemaker fibers has relevance to the intraoperative management of patients with bradyarrhythmia due to sinus node dysfunction or heart block. The authors determined the effects of halothane, enflurane, and isoflurane on automaticity and recovery of automaticity from overdrive suppression in canine Purkinje fibers derived from normal hearts. Purkinje fibers were superfused with a modified Krebs' solution (37 degrees C) containing epinephrine (2 or 15 microM) and equilibrated with a 97% O2-3% CO2 gas mixture (control). Transmembrane action potentials (AP) were recorded using standard microelectrode techniques. Purkinje fibers were then exposed to anesthetics at vaporizer settings of 0.75 or 1.5% (halothane), 1.75 or 3.5% (enflurane), and 1 or 2% (isoflurane), which were equivalent to measured superfusate concentrations of 0.22 or 0.47 mM (halothane), 0.44 or 0.94 mM (enflurane), and 0.28 or 0.53 mM (isoflurane). Compared to control, there was no significant effect of either concentration of the anesthetics on upstroke (phase 0) depolarization, AP amplitude or duration (50% repolarization), or maximum diastolic potential. All three anesthetics increased spontaneous rate. The increase in rate with all three anesthetics was due to enhanced diastolic depolarization (rate dV/dt, phase-4 depolarization). Recovery times from overdrive suppression were determined after 30 or 60 s of pacing at drive cycle lengths of 800, 500, and 400 ms and only at higher anesthetic concentrations. Recovery of automaticity was shortened by halothane only in slowly paced fibers exposed to the lower concentration of epinephrine. Under all other conditions recovery times were not affected by halothane.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

The ecology of automaticity: toward establishing the conditions needed to produce automatic processing effects.

In the past 15 years, the single term automatic has been applied to a diversity of laboratory phenomena that differ as to the preconditions necessary for their occurrence. Several major strains of automaticity are distinguished, based on the experimental conditions under which they are obtained: preconscious automatic processes, requiring only the proximal stimulus event; postconscious automatic processes, similar to preconscious effects but needing a recent activation or "priming" event for their operation; and goal-dependent automatic processes, which occur only when a specific, intentional processing goal is in place. It is argued that to more accurately specify the conditions under which an automatic effect will occur in the natural environment, greater attention needs to be given to aspects of the experimental paradigm (e.g., subjects' task goal, questionnaire administrations, previous tasks) that might be necessary to produce the effect.

Association Learning↗
PubMed1992

Automatic EEG interpretation: a new computer-assisted system for the automatic integrative interpretation of awake background EEG.

A new computer-assisted system for automatic interpretation of the awake electroencephalogram (EEG) was developed. First, all the items necessary for EEG interpretation were determined in accordance with the procedure that a qualified electroencephalographer (EEGer) goes through for the visual inspection of the background EEG activity, and then each item was defined quantitatively. For the automatic interpretation, specific EEG parameters were determined for each item so that they could fit the graded judgement of the item by the qualified EEGer as closely as possible. These specific EEG parameters were actually calculated from periodograms obtained from the time series of EEG records of 14 patients with various neurological diseases. The automatic EEG interpretation system thus established was applied to the EEG data of these 14 subjects and to 3 additional EEGs, and the results were compared with those obtained through the visual interpretation by the EEGer. This automatic EEG interpretation was found to be in good agreement with the visual interpretation by the EEGer in most EEG records. In contrast with the previous automatic analyses of EEG which were focussed on certain aspects of EEG such as the dominant rhythm, the present system is unique in its capability of providing an integrative interpretation of the spontaneous awake EEG by taking into account all its features except for paroxysmal abnormalities.

Adult↗
PubMed1985

Automatic measurement of blood pressure: evaluation of the Copal UA-231 automatic sphygmomanometer.

The suitability of an automatic sphygmomanometer for epidemiological work was evaluated in two studies. In the first, blood pressure measurements were made alternately on the automatic machine and on a Hawksley random zero instrument on 14 volunteers on each of four consecutive days by a single medical observer. No significant difference was found between the mean diastolic pressure obtained by each instrument but the mean systolic pressure was 5 mm higher on average on the automatic machine. In the second study, the effect of cuff position for the automatic instrument was examined. Differences between recommended and errant cuff positions of up to 4.5 mmHg were recorded but these did not reach statistical significance. These studies indicate that if used carefully this automatic instrument is suitable for survey and experimental use.

Adult↗
PubMed1992

Hypnotic susceptibility and verbal automaticity: automatic and strategic processing differences in the Stroop color-naming task.

The original hypothesis of Dixon, Brunet, and Laurence (1990) that highly hypnotizable (HH) subjects process words more automatically than do low hypnotizable (LH) subjects was retested in a paradigm that separated strategic from automatic processes in the Stroop color-naming task. The words red and blue preceded a color patch that was red or blue. Subjects were told that the word predicted the opposite color 75% of the time. Automatic and strategic processes were assessed by varying the interstimulus interval (ISI) between the word and the color patch. Both HH and LH subjects showed significant strategic effects (faster incongruent-trial, color-naming reaction times than congruent-trial reaction times at ISIs over 400 ms), but only HH subjects showed significant automaticity (significantly faster congruent-trial reaction times than incongruent-trial reaction times at 16.7 ms, the lowest ISI).

Adult↗
PubMed1991

Anesthetics and automaticity in latent pacemaker fibers. III. Effects of halothane and ouabain on automaticity of the SA node and subsidiary atrial pacemakers in the canine heart.

Atrial tachyarrhythmias are a common manifestation of digitalis toxicity. Such arrhythmias could be due to enhanced automaticity of subsidiary atrial pacemakers (SAP) compared to the sinoatrial (SA) node. Halothane is known to oppose digitalis-induced ventricular arrhythmias. Its effect on digitalis-caused atrial arrhythmias is unknown. Therefore, we tested two hypotheses, as follows. First, increasing ouabain concentrations would enhance automaticity of SAP compared to the SA node and that such enhanced automaticity could explain digitalis-caused atrial tachyarrhythmias. Second, halothane would oppose such enhanced automaticity of SAP, thereby opposing digitalis-caused atrial tachyarrhythmias. A canine right atrial preparation was perfused via the SA node artery with Krebs' solution (36.0 +/- 0.5 degrees C) equilibrated with 97% oxygen-3% carbon dioxide. Four bipolar extracellular electrodes recorded the site of earliest activation (SEA), which in this preparation could be the SA node or increasingly remote sites of SAP approximately 1, 2, and 3 cm distal to the SA node along the sulcus terminalis. Pacemaker shifts to SAP during exposure to drugs were scored for magnitude of shift as 1, 2, or 3 depending on which SAP site was the SEA. Magnitude scores were summed for each test condition and normalized by dividing the total number of preparations tested. Preparations (n = 48) were exposed to 1 or 2% halothane (perfusate concentrations of 0.51 +/- 0.01 or 0.79 +/- 0.03 mM, respectively) and/or to low- or mid-therapeutic (2.5 or 5 x 10(-8) M) or borderline toxic ouabain (1 x 10(-7) M). Normalized magnitude scores were not significantly different from zero (control value) with any halothane or ouabain concentration alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Anesthetics and automaticity in latent pacemaker fibers. II. Effects of halothane and epinephrine or norepinephrine on automaticity of dominant and subsidiary atrial pacemakers in the canine heart.

Knowledge of anesthetic effects on the automaticity of dominant and subsidiary cardiac pacemakers is fundamental to an understanding of mechanisms of arrhythmia during anesthesia, as well as to the management of patients with sinus node dysfunction or atrioventricular (AV) conduction block. Among potential pacemakers of the heart are subsidiary atrial pacemakers (SAP), which are located outside the classic sinoatrial (SA) node region but still within the right atrium. SAP have a higher inherent rate of automaticity than AV junctional pacemakers, may contribute to a multicentric atrial pacemaker complex, and can control the rhythm of the heart when the SA node is absent or inhibited. How halothane, epinephrine (E), or norepinephrine (NE), alone or in combination, would affect the relation between the automaticity of the SA node and SAP was tested using an isolated, perfused canine right atrial preparation (n = 78). This preparation was perfused via the SA node artery with Krebs' solution (36.0 +/- 0.5 degrees C) equilibrated with 97% oxygen-3% carbon dioxide. Delivered concentrations of halothane of 1 or 2% corresponded to measured perfusate concentrations of 0.50 +/- 0.02 or 0.80 +/- 0.04 mM in experiments with E (n = 24) and 0.45 +/- 0.02 or 0.75 +/- 0.04 mM in experiments with NE (n = 54). E or NE perfusate concentrations were 1, 2, and 5 micrograms/l or 2, 5, and 10 micrograms/l, respectively. To determine the site of earliest activation (SEA), extracellular recordings were made from the SA node region and distal sites (approximately 1, 2, and 3 cm) along the sulcus terminalis, the previously reported locations of SAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Comparison of intravenous oxytocin and prostaglandin E2 for induction of labour using automatic and non-automatic infusion techniques.

A double blind trial of prostaglandin E2 and oxytocin given by intravenous infusion after amniotomy for induction of labour in 100 primigravidae with unfavourable induction features is reported. No clear-cut advantage of either drug emerged although PGE2 was perhaps superior when the cervix was highly unfavourable. Prostaglandin E2 appeared to produce less deleterious effects on the fetus but was associated with a higher incidence of maternal side effects. The automatic Cardiff Infusion apparatus was found to be a safe means of PGE2 infusion and to have advantages over the use of non-automatic techniques both for PGE2 and for oxytocin infusion.

Adolescent↗
PubMed1992

Automaticity and cognitive anatomy: is word recognition "automatic"?

Recent progress in neural imaging technologies such as positron emission tomography and dense-array recording of event-related potentials has greatly increased the capacity for in vivo measurement of cognitively relevant processing activity within the human brain. Data from these neural imaging technologies can be combined with behavioral data from standard chronometric techniques to enhance computational modeling of human cognition. Applications of neural data to issues of attention and automaticity are illustrated in the domain of visual word recognition, addressing the question "Is word recognition automatic?"

Animals↗
PubMed1989

[Combination use of an automatic anti-tachycardia pacemaker and an automatic implantable cardioverter-defibrillator in sustained recurrent ventricular tachycardia resistant to drugs].

We used the combination of an antitachycardia automatic ventricular pacemaker with the automatic implantable cardioverter-defibrillator in two patients with sustained, recurrent, drug-resistant ventricular tachycardias in whom a surgical ablation was not indicated. The indications for the combined use of the two systems were the possibility to control: a) the ventricular tachycardias with ventricular programmed stimulation; b) the arrhythmias which might eventually degenerate into ventricular flutter or fibrillation (as a result of anti-tachycardia pacing) with the defibrillator. To avoid any possible interference between the two systems we used the following protocol: a) endocardial bipolar pacing; b) the sensing electrodes of the defibrillator were placed as far as possible from the endocardial one; c) a suitable programming of the pacemaker output; d) a careful selection of the anti-tachycardia pacing programme (burst rate inferior to the cut-off rate of the cardioverter-defibrillator and/or a duration of the burst pacing inferior to the arrhythmia sensing time of the defibrillator); e) use of cardioverter-defibrillators with a high cut-off rate. We never observed, during the follow-up (11 and 4 months, respectively), interference between the two systems. Both patients had ventricular tachycardia recurrences (51 and 3 episodes, respectively). The arrhythmias were correctly detected and interrupted by the pacemaker without the intervention of the defibrillator. These data confirm the feasibility of the combined use of the two systems in patients with ventricular tachycardias and, in selected cases, this approach is preferable. The anti-tachycardia pacemaker counteracts some limitations of the defibrillators available at present. It offers a protection against bradyarrhythmias and allows a more precise storage of arrhythmic events. The anti-tachycardia pacemaker often controls ventricular tachycardias without the intervention of the defibrillator, thus giving the same a longer life-span and allowing patients to avoid the shock.

Aged↗
PubMed1977

[Automatic analysis of long-term EEG in epilepsy. First experiences with a new part-automatic analytic system (author's transl)].

A new equipment for automatic analysis of prolonged EEG derivations is demonstrated. Spikes, waves and SW-combinations are detected and counted separate; counted EEG signals are written with paper speed of 25 mm per sec. Results of a 3-channel-derivation with 1-channel-analysis are shown in a time compressed graphic demonstration. The method gives better information about pathological EEG-signals of one hour or more in epileptic patients, drug effects can be demonstrated easily, and detection of pathological EEG signals is simplified.

Diagnosis, Computer-Assisted↗
PubMed1976

[Automatic clinical electrocardiography laboratory of the Udine regional hospital. Considerations on 50,000 tracings automatically analyzed with computers].

Automatic ECG processing has now passed beyond the experimental stage into the realm of clinical practice. It offers the most advanced solution to the organisation problems faced by ECG laboratories, particularly in large hospitals. A centralised laboratory for this work was first set up in Italy in 1973 at the Udine Regional Hospital. Its instrumentation and organisation are described and a consecutive sample of 1000 ECGs culled from the 50,000 computerised since its inception are discussed.

Diagnosis, Computer-Assisted↗
PubMed1976

The cleaning and disinfection by heat of bedpans in automatic and semi-automatic machines.

This work is concerned with the cleaning and disinfection by heat of stainless-steel and polypropylene bedpans, which had been soiled with either a biological contaminant, human serum albumin (HSA) labelled with technetium-99m 99m(Tc), or a bacteriological contaminant, streptococcus faecalis mixed with Tc-labelled HSA. Results of cleaning and disinfection achieved with a Test Machine and those achieved by procedures adopted in eight different wards of a general hospital are reported. Bedpan washers installed in wards were found to be less efficient than the Test Machine, at least partly because of inadequate maintenance. Stainless-steel and polypropylene bedpans gave essentially the same results.

Automation↗
PubMed1988

[Measurement of arterial pressure by an automatic method. Comparison of various devices for automatic measurement].

A comparative study of three Dinamap 845 instruments was carried out in order to find out whether the use of several automated blood pressure recorders constitutes a major source of variations in epidemiological studies. The three instruments were compared by means of a variant analysis model and proved to have virtually the same accuracy. Only one of them gave a slightly different diastolic pressure reading. No matter how useful are instruments for automated blood pressure measurement, comparisons between several recorders of the same type and regular testing for accuracy seem to be necessary in epidemiological studies.

Analysis of Variance↗