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PubMed1986

Semi-automatic image-analysis applied to the quantification of bone microstructure.

Bone microstructure can be quantified by methods ranging from simple manual techniques to fully automatic image analysis systems. We describe a semi-automatic method, developed in BASIC and running on a laboratory microcomputer. Its core is based on two special algorithms for image conversion and for calculation. These two algorithms produce quantifying characteristics for any irregularly shaped structure, as defined by one or more open or closed contour lines. The quantification of these structural parameters relies only on contour line digitization. The improved efficiency of this semi-automatic method is a consequence of combining automatic calculations and human assistance. The structural parameters chosen were for a specific research project; the correlation between mechanical and microstructural properties of cortical bone, but they may readily be changed as circumstances demand.

Biomechanical Phenomena↗
PubMed1991

Radiation dosimetry by automatic image analysis of dicentric chromosomes.

A system for scoring dicentric chromosomes by image analysis comprised fully automatic location of mitotic cells, automatic retrieval, focus and digitization at high resolution, automatic rejection of nuclei and debris and detection and segmentation of chromosome clusters, automatic centromere location, and subsequent rapid interactive visual review of potential dicentric chromosomes to confirm positives and reject false positives. A calibration set of about 15,000 cells was used to establish the quadratic dose response for 60Co gamma-irradiation. The dose-response function parameters were established by a maximum likelihood technique, and confidence limits in the dose response and in the corresponding inverse curve, of estimated dose for observed dicentric frequency, were established by Monte Carlo techniques. The system was validated in a blind trial by analysing a test set comprising a total of about 8000 cells irradiated to 1 of 10 dose levels, and estimating the doses from the observed dicentric frequency. There was a close correspondence between the estimated and true doses. The overall sensitivity of the system in terms of the proportion of the total population of dicentrics present in the cells analysed that were detected by the system was measured to be about 40%. This implies that about 2.5 times more cells must be analysed by machine than by visual analysis. Taking this factor into account, the measured review time and false positive rates imply that analysis by the system of sufficient cells to provide the equivalent of a visual analysis of 500 cells would require about 1 h for operator review.

Cells, Cultured↗
PubMed1988

A new rhythm library for testing automatic external defibrillators: performance of three devices.

A library of arrhythmias obtained from patients with cardiac arrest was developed. Such a data base will permit both in vitro testing of the rhythm analysis system of automatic external defibrillators before clinical field trials are conducted and comparison of devices. Defibrillators equipped with voice/electrocardiographic tape recorders and used in the prehospital defibrillation programs in Iowa and King County, Washington provided the rhythm source. From these recordings, segments of ventricular fibrillation with minimal artifact and a duration of greater than or equal to 6 s were selected. Segments of ventricular fibrillation (n = 102) were categorized by average peak amplitude as fine (1 to less than 3 mm), medium (3 to less than 7 mm), coarse (7 to less than 12 mm) and extra coarse (greater than or equal to 12 mm), and transcribed onto high fidelity videocassette tapes. Nonventricular fibrillation cardiac arrest rhythms (n = 144), which included wide complex idioventricular rhythms, ventricular and supraventricular tachycardias, asystole and artifact, were also transcribed. Automatic external defibrillators developed by three manufacturers reached a treat (shock) decision on 88 to 93% of the ventricular fibrillation rhythms and on 5 to 10% of the nonventricular fibrillation rhythms. The latter decisions were defined as false positive, though for many rapid nonventricular fibrillation rhythms, countershock may be the appropriate treatment response. There were no statistically significant differences among the three devices in the shock/no shock decisions. A variety of ventricular fibrillation arrhythmias and terminology to express the preclinical performance of automatic external defibrillators are defined. Three commercially available automatic external defibrillators appear to successfully identify ventricular fibrillation and nonventricular fibrillation rhythms.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMedDate not supplied

The concept of automatic reinforcement: implications for behavioral research in developmental disabilities.

Automatic reinforcement refers to situations in which behavior is maintained by operant mechanisms independent of the social environment. A number of difficulties exist in conducting an adequate functional analysis of automatically reinforced aberrant behavior. For example, sources of reinforcement are often difficult or impossible to identify, manipulate, or control. Further, the development of treatments is often difficult because many behavioral interventions, such as timeout, involve manipulation of the social environment--an approach that may be functionally irrelevant in the case of automatic reinforcement. This article discusses the problems inherent in the analysis of automatically reinforced behavior and reviews four classes of treatment that are compatible with that behavioral function. The four types of intervention reviewed include manipulations of establishing operations, sensory extinction, differential reinforcement, and punishment. Suggestions for future research are discussed.

Conditioning, Operant↗
PubMed2006

Automatic associations with the sensory aspects of smoking: positive in habitual smokers but negative in non-smokers.

To test whether pictorial stimuli that focus on the sensory aspects of smoking elicit different automatic affective associations in smokers than in non-smokers, 31 smoking and 33 non-smoking students completed a single target IAT. Explicit attitudes were assessed using a semantic differential. Automatic affective associations were positive in smokers but negative in non-smokers. Only automatic affective associations but not self-reported attitudes were significantly correlated with craving. Together these findings are consistent with the idea that positive (automatic) attitudes are involved in smoking behavior and support the view that direct and indirect measures tap different cognitive motivational systems.

Adolescent↗
PubMed2005

Automatic intraaortic balloon pump timing using an intrabeat dicrotic notch prediction algorithm.

PURPOSE: The efficacy of intraaortic balloon counterpulsation (IABP) during arrhythmic episodes is questionable. A novel algorithm for intrabeat prediction of the dicrotic notch was used for real time IABP inflation timing control. DESCRIPTION: A windkessel model algorithm was used to calculate real-time aortic flow from aortic pressure. The dicrotic notch was predicted using a percentage of calculated peak flow. Automatic inflation timing was set at intrabeat predicted dicrotic notch and was combined with automatic IAB deflation. EVALUATION: Prophylactic IABP was applied in 27 patients with low ejection fraction (< 35%) undergoing cardiac surgery. Analysis of IABP at a 1:4 ratio revealed that IAB inflation occurred at a mean of 0.6 +/- 5 ms from the dicrotic notch. In all patients accurate automatic timing at a 1:1 assist ratio was performed. Seventeen patients had episodes of severe arrhythmia, the novel IABP inflation algorithm accurately assisted 318 of 320 arrhythmic beats at a 1:1 ratio. CONCLUSIONS: The novel real-time intrabeat IABP inflation timing algorithm performed accurately in all patients during both regular rhythms and severe arrhythmia, allowing fully automatic intrabeat IABP timing.

Aged↗
PubMed2006

Integrated and automatic mixing of whole blood: an evaluation of a novel blood gas analyzer.

BACKGROUND: A homogeneous whole blood specimen is essential to produce quality results from blood gas analysis, however achieving an adequately mixed specimen can be difficult due to the absence of any dead space in a blood gas syringe. This study evaluated the efficacy of an automatic mixing feature incorporated into the ABL800 FLEX blood gas analyzer and estimated the systematic error in tests performed by the instrument. METHODS: Quantitative measurements of pH, PCO(2), PO(2), Na(+), K(+), Ca(+), glucose, lactate, and total hemoglobin were performed on 388 whole blood specimens collected into standard blood gas syringes or specific syringes designed to work in conjunction with the ABL800 FLEX. One hundred eighty specimens were manually or automatically mixed following horizontal storage for 10, 20, or 30 min and total hemoglobin was used as in indicator of specimen homogeneity. Two hundred eight specimens were used to estimate the systematic error of tests performed by the ABL800 FLEX. RESULTS: Manual mixing produced significantly more variation in paired hemoglobin measurements compared to automatic mixing at all three time points (p<0.0001). All estimates of systematic error were very low and clinically insignificant. Quantitative results showed excellent agreement with a reference analyzer. CONCLUSIONS: In contrast to manual mixing, automatic mixing by the ABL800 FLEX consistently produces a homogeneous specimen.

Adult↗
PubMed2006

First clinical experience with an automatic control system for rotary blood pumps during ergometry and right-heart catheterization.

BACKGROUND: At present, most clinically implanted rotary blood pumps are operated at constant speed and adjusted by the physician. It is generally assumed that an adaptation of pump speed to the patient's physiologic requirements would be beneficial. The data provided in this paper, based on hemodynamic and spirometric data during exercise in which a pre-load-sensitive control was used, lend quantitative support to this assumption. METHODS: An automatic speed control was developed and implemented with Matlab on a dSpace controller board. The system uses pump speed, pump power, and pump flow as its only input signals. It was connected to the clinical hardware of the DeBakey VAD System. The control is pre-load-sensitive and uses an expert system to detect excessive unloading and eventual suction. This system was used to quantify the cardiovascular reaction of patients to both automatically controlled and constant pump speed. A sub-group of 5 patients underwent bicycle ergometry with Swan-Ganz catheterization and spiroergometry. RESULTS: The automatic, closed-loop speed control showed robust and stable performance. It provided an increase in pump flow (+0.94 +/- 0.5 liters/min, p < 0.05) compared with constant-speed mode in response to physical activity. Pulmonary arterial (PAP) and capillary wedge pressure (PCWP) clearly decreased (-7.4 +/- 4.1 mm Hg for PAP and -8.3 +/- 4.2 mm Hg for PCWP, p < 0.05), and venous oxygen saturation moderately increased (+5.2%). CONCLUSION: An automatic speed-control system for rotary blood pumps was developed and demonstrated by spiroergometry to be appropriately responsive to physiologic demand.

Algorithms↗
PubMed2006

Automatic extraction of the mid-facial plane for cranio-maxillofacial surgery planning.

Recently developed computer applications provide tools for planning cranio-maxillofacial interventions based on 3-dimensional (3D) virtual models of the patient's skull obtained from computed-tomography (CT) scans. Precise knowledge of the location of the mid-facial plane is important for the assessment of deformities and for planning reconstructive procedures. In this work, a new method is presented to automatically compute the mid-facial plane on the basis of a surface model of the facial skeleton obtained from CT. The method matches homologous surface areas selected by the user on the left and right facial side using an iterative closest point optimization. The symmetry plane which best approximates this matching transformation is then computed. This new automatic method was evaluated in an experimental study. The study included experienced and inexperienced clinicians defining the symmetry plane by a selection of landmarks. This manual definition was systematically compared with the definition resulting from the new automatic method: Quality of the symmetry planes was evaluated by their ability to match homologous areas of the face. Results show that the new automatic method is reliable and leads to significantly higher accuracy than the manual method when performed by inexperienced clinicians. In addition, the method performs equally well in difficult trauma situations, where key landmarks are unreliable or absent.

Algorithms↗
PubMed2004

Automatic localization of the prostate for on-line or off-line image-guided radiotherapy.

PURPOSE: With higher radiation dose, higher cure rates have been reported in prostate cancer patients. The extra margin needed to account for prostate motion, however, limits the level of dose escalation, because of the presence of surrounding organs at risk. Knowledge of the precise position of the prostate would allow significant reduction of the treatment field. Better localization of the prostate at the time of treatment is therefore needed, e.g. using a cone-beam computed tomography (CT) system integrated with the linear accelerator. Localization of the prostate relies upon manual delineation of contours in successive axial CT slices or interactive alignment and is fairly time-consuming. A faster method is required for on-line or off-line image-guided radiotherapy, because of prostate motion, for patient throughput and efficiency. Therefore, we developed an automatic method to localize the prostate, based on 3D gray value registration. METHODS AND MATERIALS: A study was performed on conventional repeat CT scans of 19 prostate cancer patients to develop the methodology to localize the prostate. For each patient, 8-13 repeat CT scans were made during the course of treatment. First, the planning CT scan and the repeat CT scan were registered onto the rigid bony structures. Then, the delineated prostate in the planning CT scan was enlarged by an optimum margin of 5 mm to define a region of interest in the planning CT scan that contained enough gray value information for registration. Subsequently, this region was automatically registered to a repeat CT scan using 3D gray value registration to localize the prostate. The performance of automatic prostate localization was compared to prostate localization using contours. Therefore, a reference set was generated by registering the delineated contours of the prostates in all scans of all patients. Gray value registrations that showed large differences with respect to contour registrations were detected with a chi(2) analysis and were removed from the data set before further analysis. RESULTS: Comparing gray value registration to contour registration, we found a success rate of 91%. The accuracy for rotations around the left-right, cranial-caudal, and anterior-posterior axis was 2.4 degrees, 1.6 degrees, and 1.3 degrees (1 SD), respectively, and for translations along these axes 0.7, 1.3, and 1.2 mm (1 SD), respectively. A large part of the error is attributed to uncertainty in the reference contour set. Automatic prostate localization takes about 45 seconds on a 1.7 GHz Pentium IV personal computer. CONCLUSIONS: This newly developed method localizes the prostate quickly, accurately, and with a good success rate, although visual inspection is still needed to detect outliers. With this approach, it will be possible to correct on-line or off-line for prostate movement. Combined with the conformity of intensity-modulated dose distributions, this method might permit dose escalation beyond that of current conformal approaches, because margins can be safely reduced.

Algorithms↗
PubMed2004

Comparison of conventional nighttime with automatic or manual daytime CPAP titration in unselected sleep apnea patients: study of the usefulness of daytime titration studies.

Daytime CPAP titration studies with full polysomnography have been successfully performed in patients with severe sleep apnea-hypopnea syndrome (SAHS). The implementation of daytime studies in unselected SAHS patients could help to reduce the waiting lists for CPAP titrations. The main purpose of this study was to compare the effectiveness of conventional versus manual or automatic daytime CPAP titration in unselected patients with SAHS. Ninety-three consecutive patients with SAHS in whom CPAP was indicated were assigned to conventional titration or to manual or automatic (AutoSet) daytime CPAP titration, after sleep deprivation. The number of valid studies, sleep architecture, final pressure selected and mean pressure in the different sleep stages were compared. Changes in sleepiness (Epworth sleepiness score) and hours of CPAP use were assessed after 3 months of treatment. Four patients did not sleep (3 AutoSet, 1 conventional daytime groups). Sleep latency was shorter during automatic daytime titration whereas REM latency was shorter in daytime studies; the percentage of sleep stages was similar during all types of titration. CPAP requirements were significantly higher during REM sleep in conventional and manual daytime titrations while mean pressure was unchanged throughout sleep stages during AutoSet titration. CPAP pressure selected with conventional or daytime manual titration (7.5(2.2) cm H2O and 7.4(1.5) cm H2O, ns) were significantly lower (P< 0.001) than with AutoSet (9.4(1.6) cm H20. All groups showed similar decrease of sleepiness and hours of use of CPAP at 3 months of follow-up. Automatic and manual daytime PSG studies after sleep deprivation are useful for CPAP titration in unselected patients with SAHS. Pressure selected with AutoSet is significantly higher than with conventional daytime or nighttime titration, although not significant in terms of treatment compliance and symptom improvement.

Adult↗
PubMed1978

Semi-automatic data processing in clinical chemistry.

A semi-automatic system for data processing in the Clinical Chemistry Department of the School of Pathology, Johannesburg, is outlined. Careful planning of workflow in the laboratory can provide a better interface of laboratory results with a manual cumulative reporting system in which technologists and clerks co-ordinate their activities. The system used provides a less tedious and less error-prone process via automatic printing facilities. This system achieves improved patient care in terms of quality control (data checks) and cumulative reporting of results. Facility for accounts and administration purpose are also incorporated. In our experience, semi-automatic data processing can provide a solution to the clerical problems generated by the introduction of automatic testing equipment. Hardware costs are minimal in comparison to fully automated systems, which utilize on-line or off-line computers.

Chemistry, Clinical↗
PubMed1990

Dissociations of language functions in aphasics with speech automatisms (recurring utterances).

The linguistic performance of 27 aphasics with frequent production of non-lexical speech automatisms (recurrent utterances; e.g. do-do-do...) in spontaneous speech was investigated. Of the 26 patients examined with the Aachen aphasia test (AAT), 24 cases suffered from global aphasia, one from Broca's aphasia, and one was not classifiable but most resembled the fluent types as Wernicke's or conduction aphasia. While most patients were severely impaired in language comprehension, a subgroup showed impairments on a moderate level. In four cases clear dissociations between oral and written output performance were found. Only one patient, and very rarely so, interspersed his written output with his speech automatism. Analysis of written output within the theoretical framework of the logogen model provided evidence for the possibility of a partially intact phonological system in patients with speech automatisms. Results are interpreted as supporting a sub-phonemic hypothesis of the generation of non-lexical speech automatisms.

Adult↗
PubMed1985

Ventricular arrhythmias following one-stage and two-stage coronary reperfusion: evidence for both reentry and enhanced automaticity.

We studied the effects of reperfusion in 60 dogs following a 30-45 minute period of left anterior descending coronary artery occlusion using electrocardiograms and composite electrogram recordings. One-stage reperfusion in 14 of 15 dogs produced ventricular arrhythmias which degenerated into ventricular fibrillation within 60 seconds. The onset of ventricular arrhythmias was associated with continuous electrical activity in epicardial and intramural electrograms recorded from the reperfused zone. Vagal slowing during reperfusion (64 +/- 8/min) did not prevent ventricular fibrillation (eight of eight dogs) and escape beats were often followed by one or more coupled ectopic beats associated with continuous electrical activity. Rapid atrial pacing (270/min) also did not prevent the appearance of ventricular arrhythmia with associated continuous electrical activity and ventricular fibrillation (six of six dogs) nor did 4 mg/kg lidocaine (15 of 16 dogs). In another group of 15 dogs reperfusion was performed in two stages resulting in no ventricular fibrillation but in 8 of 15 dogs ventricular arrhythmias were observed beginning within two minutes after reperfusion and lasting 20-30 minutes. These ventricular arrhythmias were not associated with continuous electrical activity in any of the recorded leads. Atrial pacing suppressed ventricular arrhythmias and idioventricular rate averaged 157 +/- 10/min versus 55 +/- 10/min pre-reperfusion control. The earliest site of activation indicated automatic foci arising in the subendocardium of the reperfused zone. Lidocaine (2-4 mg/kg) rapidly (less than 90 sec) restored normal sinus rhythm and suppressed automaticity (72 +/- 11/min) as did left anterior descending artery reocclusion (52 +/- 6/min). We conclude that both reentry and enhanced automaticity play a role in ventricular arrhythmias due to reperfusion. Lidocaine (2-4 mg/kg) suppresses automatic but not reentrant ventricular arrhythmias in this experimental setting.

Animals↗
PubMed1992

Simplified enrollment for autologous transfusion: automatic referral of presurgical patients for assessment for autologous blood collections.

We implemented a pilot program at our institution for automatic referral of patients for presurgical assessment for preoperative and intraoperative collection of autologous blood. Although patients and clinicians support the use of autologous transfusion, often a request for collection of autologous blood is not initiated. During 11 months, 269 patients (82%) of three orthopedic surgeons entered the program, and 218 underwent operation and were dismissed from the hospital. A total of 940 units of autologous blood (675 preoperatively and 265 intraoperatively) was collected from these 218 patients, and 84% of the units were transfused. Throughout hospitalization, 86% of the patients received only autologous blood, whereas 14% received various proportions of homologous and autologous blood. In contrast, only 26% of a concomitant control group of 220 consecutive orthopedic surgical patients not participating in the automatic-referral program received only autologous blood. Thus, the automatic-referral program increased the percentage of elective orthopedic surgical patients who received only autologous blood from 26% to 86% (P less than 0.001). This study also showed that the same amount of blood was used for autologous transfusions as was routinely used for homologous transfusions in similar cases. The automatic-referral system was convenient for physicians and patients and offered the benefits of reduction of transfusion-associated risks and amelioration of patient anxieties.

Blood Transfusion, Autologous↗
PubMed1999

Differences in semantic category priming in the left and right cerebral hemispheres under automatic and controlled processing conditions.

The contribution of each cerebral hemisphere to the generation of semantic category meanings at automatic and strategic levels of processing was investigated in a priming experiment where prime and target words were independently projected to the left or right visual fields (LVF or RVF). Non-associated category exemplars were employed as related pairs in a lexical decision task and presented in two experimental conditions. The first condition was designed to elicit automatic processing, so related pairs comprised 20% of the positive set, stimulus pairs were temporally separated by a stimulus onset asynchrony (SOA) of 250 ms, and there was no allusion to the presence of related pairs in the instructions to subjects. The second condition, designed to invoke controlled processing, incorporated a relatedness proportion of 50%, stimulus pairs separated by an SOA of 750 ms, and instructions which informed subjects of the presence and use of category exemplar pairs in the stimulus set. In the first condition, a prime directed to either visual field facilitated responses to categorically related targets subsequently projected to the RVF, while in the second condition a prime directed to either visual field facilitated responses to related targets projected to the LVF. The facilitation effects obtained in both conditions appeared to reflect automatic processes, while strategic processes were invoked in the left, but not the right hemisphere in the second condition. The results suggest that both hemispheres have automatic access to semantic category meanings, although the timecourse of activation of semantic category meanings is slower in the right hemisphere than in the left.

Adult↗
PubMed2002

Development of a digital signal processor-based new 12-lead synchronization electrocardiogram automatic analysis system.

This paper presents a digital signal processor (DSP)-based new multichannel electrocardiogram (ECG) system for 12-lead synchronization ECG automatic analysis in real-time with high sampling rate at 1000 Hz and 12-bits precision. Using the hardware structure of double-CPU based on Microprocessor (MPU) 89C55 and DSP TMS320F206 combines the powerful control ability of MPU with DSPs fast computation ability. Fully utilizing the double-CPUs resource, the system can distribute the reasonable CPU-time for the real-time tasks of multichannel synchronization ECG sampling, digital filter, data storing, waveform automatic analysis and print at high sampling rate. The digital ECG system has the advantages of simple structure, sampling with high speed and precision, powerful real-time processing ability and good quality. The paper discusses the system's principle and the skilful hardware design, also gives the ECG processing using the fast simple integer-coefficient filter method and the automatic calculation algorithms of the ECG parameters such as heart rate, P-R interval, Q-T interval and deflexion angle of ECG-axis etc. The system had been successfully tested and used in the ECG automatic analysis instrument.

Automation↗
PubMedDate not supplied

Successful automatic external defibrillator operation by people trained only in basic life support in a simulated cardiac arrest situation.

OBJECTIVE: To show whether in an in-hospital cardiac arrest, early defibrillation can also be performed by hospital staff trained only in basic life support. BACKGROUND: The International Liaison Committee on Resuscitation (ILCOR) endorses the concept that in many settings non-medical individuals should be allowed and encouraged to use defibrillators. METHODS: Five different groups of hospital staff were evaluated whether they were able to correctly operate an automatic external defibrillator in a simulated sudden cardiac arrest situation without any prior instruction. The participants were assigned either to the 'basic life support-trained' group (BLS, n = 40, or to the 'advanced life support-trained' group (ALS, n = 40). RESULTS: All persons of the 'only BLS-trained' group delivered the three sequential ('stacked') shocks with the automatic external defibrillator when persistent ventricular fibrillation was simulated. The 'ALS-trained' persons successfully delivered the three shocks with the automatic external defibrillator in 98% of the cases. When this group used a conventional defibrillator, only 88% were able to deliver the three shocks, however they were able to do it significantly more quickly. CONCLUSION: Using an automatic defibrillator without any prior instruction, even persons trained only in BLS were able to deliver three sequential shocks in a simulated persistent ventricular fibrillation cardiac arrest.

Adult↗