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PubMed1982

Concepts for automatic perimetry, as applied to the Scoperimeter, an experimental automatic perimeter.

The development of an experimental automatic perimeter, the Scoperimeter, is described. We use an oscilloscope as campimeter screen for the examination of the central 25 degrees of the visual field. The oscilloscope beam generates a homogeneous background luminance (0.1 cd/m2) and single stimulus static stimuli in any given position. The effective luminance-range of the stimuli is 3.0-3.5 log.unit. The visual field examination is controlled by a small computer system. Four examination programs written in Basic, are described. The screening programs using threshold related suprathreshold stimuli appear to be the most efficient compromise between speed and accuracy of the examination. The printout of these programs consists of a noninterpolated grey-scale presentation. Other programs perform static meridional perimetry or measure luminance threshold in 60 regularly distributed positions in the visual field. We have taken into consideration the factors that may influence the outcome of the examination: the presence of an instruction phase, the possibility to follow the progress of the examination and careful stimulus-timing. In a second paper we present clinical results we obtained using our instrument.

Humans↗
PubMed2002

Adjustment of maximum automatic sensitivity (automatic gain control) reduces inappropriate therapies in patients with implantable cardioverter defibrillators.

Patients with ICDs might experience oversensing associated with inappropriate shock therapy when paced at low bradycardia rates or if they have a low intrinsic rhythm. The amplifier gain of automatic gain control is maximal at long RR intervals and might lead to oversensing of myopotentials. The hypothesis was that an individual adjustment of the sensitivity floor could reduce inappropriate ICD therapies. Fourteen patients implanted with the VENTAK MINI I/II and III in whom oversensing and/or inappropriate shocks had been documented were included in this evaluation based on stored episodes. Sensitivity was modified in all ICDs by means of noninvasive software downloading that allowed reprogramming of the maximum sensitivity from 0.14 mV in two steps to 0.27 mV ("Normal," "Less," "Least"). Provocation testing (deep inspiration, sit-ups, and abdominal pressing) was conducted at "Nominal" settings (0.14 mV) while the intracardiac electrogram with annotated event marker was running continuously and was repeated at 0.22 mV (Less) and 0.27 mV (Least). All patients evaluated had documented spontaneous episodes due to oversensing before the sensitivity floor was reprogrammed. During provocation testing at Nominal settings, oversensing could be documented in 9 of (64.3%) 14 patients. Provocation testing was repeated after the sensitivity selection was reprogrammed and oversensing could not be provoked in any of the 14 implanted devices. Sensitivity was reprogrammed in all 14 patients to a higher value (5 patients Less, 9 patients Least). After sensitivity adjustment, VF was induced in all patients to verify appropriate arrhythmia detection and termination. Sensitivity reprogramming in patients with documented oversensing eliminates the incidence of inappropriate shock therapy without compromising the ability to detect VF appropriately.

Algorithms↗
PubMed2003

Automatic external defibrillators for prevention of out-of-hospital sudden death: effectiveness of the automatic external defibrillator.

Approaches to the prevention of sudden cardiac death (SCD) include strategies designed to attack the problem from the multiple perspectives of primary prevention of the underlying diseases, prophylactic treatment of high-risk individuals with identified diseases, and responses to cardiac arrest victims in the community. The latter strategy began with conventional fire department-based emergency rescue systems (emergency medical services [EMS]) that originated in the early 1970s. Although such systems were innovative and impressive at the time, they are limited by less-than-optimal response times that translate to low survival rates. Newer strategies, designed to respond faster, include a variety of methods, including ambulance- and police-based automatic external defibrillators (AEDs), deployment of AEDs in settings in which crowds accumulate and designated rescuers are available, and more general public access sites. The value of conventional EMS systems remains because of their ability to provide advanced life support as part of a dual-response system. These approaches, in conjunction with better primary and secondary prevention strategies, offer the hope of reducing the SCD burden.

Arrhythmias, Cardiac↗
PubMed2001

Is arrhythmia detection by automatic external defibrillator accurate for children?: sensitivity and specificity of an automatic external defibrillator algorithm in 696 pediatric arrhythmias.

BACKGROUND: Use of automatic external defibrillators (AEDs) in children aged <8 years is not recommended. The purpose of this study was to develop an ECG database of shockable and nonshockable rhythms from a broad age range of pediatric patients and to test the accuracy of the Agilent Heartstream FR2 Patient Analysis System for sensitivity and specificity. METHODS AND RESULTS: Children aged </=12 years who either developed arrhythmias or were at risk for developing arrhythmias were studied. Two sources were used for the database: children whose rhythms were recorded prospectively via a modified AED and children who had arrhythmias captured on paper and digitized for subsequent analysis. The rhythms were divided into 5-second strips, classified by 3 reviewers, and then assessed by the AED analysis algorithm. A total of 696 five-second rhythm strips from 191 children (81 female and 110 male) aged 1 day to 12 years (median 3.0 years) were analyzed. There was 100% specificity for nonshockable rhythms. Sensitivity for ventricular fibrillation was 96%. CONCLUSIONS: There was excellent AED rhythm analysis sensitivity and specificity in all age groups for ventricular fibrillation and nonshockable rhythms. The high specificity and sensitivity indicate that there is a very low risk of an inappropriate shock and that the AED correctly identifies shockable rhythms, making the algorithm both safe and effective for children.

Adult↗
PubMed1998

The cost-effectiveness of automatic implantable cardiac defibrillators: results from MADIT. Multicenter Automatic Defibrillator Implantation Trial.

BACKGROUND: The recently reported Multicenter Automatic Defibrillator Implantation Trial (MADIT) showed improved survival in selected asymptomatic patients with coronary disease and nonsustained ventricular tachycardia. The economic consequences of defibrillator management in this patient population are unknown. METHODS AND RESULTS: Patients were followed up to quantify their use of healthcare services, including hospitalizations, physician visits, medications, laboratory tests, and procedures, during the trial. The costs of these services, including the costs of the defibrillator, were determined in patients randomized to defibrillator and nondefibrillator therapy. Incremental cost-effectiveness ratios were calculated by relating these costs to the increased survival associated with the use of the defibrillator. The average survival for the defibrillator group over a 4-year period was 3.66 years compared with 2.80 years for conventionally treated patients. Accumulated net costs were $97,560 for the defibrillator group compared with $75,980 for individuals treated with medications alone. The resulting incremental cost-effectiveness ratio of $27,000 per life-year saved compares favorably with other cardiac interventions. Sensitivity analyses showed that the incremental cost-effectiveness ratio would be reduced to approximately $23,000 per life-year saved if transvenous defibrillators were used instead of the older devices, which required thoracic surgery for implantation. CONCLUSIONS: An implanted cardiac defibrillator is cost-effective in selected individuals at high risk for ventricular arrhythmias.

Cost-Benefit Analysis↗
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↗
PubMed1997

[Sensitivity S of film-screen systems and mode of operation of different automatic exposure systems in general practice conditions. II: Automatic exposure systems].

A new method is presented to check several automatic exposure control systems (AEC) for their suitability in radiological image production. It is based on measurements of dose and density with water as an absorbing and scattering medium. The characteristic curves of an AEC can be recorded, i.e., in what way is the dose K in the image receptor plane regulated by the AEC in dependence on the different radiation qualities and the specific water volume. These characteristics can be compared with several screen-film systems (SFS), i.e., which dose K is required by the SFS in dependence on the X ray tube voltage (kV) to get the net density of Dn = 1.00. It is possible to check the way of operating of an AEC with sufficient accuracy but less time and energy are needed. The disparity of the characteristics of AEC and SFS and their results on radiological examination are discussed.

Humans↗
PubMed2002

[Hearing screening with automatic evaluation of TEOAE and a new method of automatic evaluation of early auditory evoked potentials. Optimization and field trial].

BACKGROUND AND OBJECTIVE: To make a rational decision as to which screening test might be adequate as a universal newborn hearing screening, different methods have to be tested under "real-life" conditions. In addition, a good reference is required as "golden standard." PATIENTS/METHODS: In the study presented here, an ABR with a novel algorithm for threshold-estimation was optimized and compared to TEOAE (Echoscreen) and DPOAE (GSI 60) in a three-step protocol using a standard click-evoked ABR (Evoselect) as reference of sensitivity and specificity. RESULTS: 26 ears were found to be hearing-impaired. All of them were also detected by each of the screening method (sensitivity 100%). Specificity in the final "step 2" of the study was around 87.7/92.3% for Echoscreen, 82.4/84.4% for DPOAE and 82.4/89.1 for Evoflash (left/right, respectively). Differences were not at all significant (X2-test, p > > 0.05). In summary, results were somewhat inferior to those found by other authors, probably due to more difficult conditions in the "real-life" setting. CONCLUSIONS: A higher rate of false-alarm shows that a two-step screening is necessary. Therefore, increased resources for diagnostic procedures are required.

Adolescent↗