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PubMed1975

Predictive validities of several clinical color vision tests for aviation signal light gun performance.

Scores on the American Optical Company (AOC) test (1965 edition), Dvorine test, Farnsworth Lantern test, Color Threshold Tester, Farnsworth-Munsell 100-Hue test, Farnsworth Panel D-15 test, and Schmidt-Haensch Anomaloscope were obtained from 137 men with color-defective vision and 128 men with normal color vision. The validity of each of these tests in predicting scores on the aviation signal light gun was assessed by using daytime and nighttime administrations of the light gun as the criteria. Two "best sets" of plates from the AOC and Dvorine tests were selected by calculating a multiple regression equation in a stepwise manner with the nighttime and then the daytime administration of the signal light gun test as the criteria. Based on a graphic presentation of the miss and false alarm rates for each test at various possible cut scores, suggestions were made regarding the use of each test and the selection of optimal pass/fail scores.

Aerospace Medicine↗
PubMed2004

[A change in the alarm level entails a change in behavioural strategy of mice in stress and a change in analgesia induced by it].

The effects of anxiogenic (pentylentetrazole) and anxiolytic (diazepam) agents on < > and cold swim stress-induced analgesia were investigated in SHR and NMRI male mice. It was shown that behavioral response to acute stress was associated with a change in the pain tolerance threshold. Diazepam increased immobility time and attenuated stress-induced analgesia (SIA). NMRI mice were more responsive to anxiolytic than the SHR mice, but the lattes manifested more dramatic changes when anxiety was pharmacologically enhanced (immobility time was significantly reduced and the SIA exaggerated). Our findings suggest that the main parameters change in reciprocal manner following a pharmacologically altered anxiety, and reveal that differences between two strains of mice are determined by differences in their sensitivity to stress.

Animals↗
PubMed2005

["Highlights" in emergency medicine -- severe head trauma, polytrauma and cardiac arrest].

According to scientific publications focusing on emergency medicine and published in international journals in the past few months, new and clinically important results can be identified. In patients with severe head trauma (SHT), application of hypertonic solutions is possible; long term outcome, however, is not improved by this measure. Prehospital capnometry is important, because otherwise up to 40 % of all mechanically ventilated patients are hypoventilated. In a study in 200 patients with prehospital cardiac arrest and ventricular fibrillation as initial cardiac rhythm, subgroup analysis (alarm-response time > 5 min) showed an increase in survival rate (14 % vs. 2 %), if defibrillation was proceeded by 3 min of conventional cardiopulmonary resuscitation (CPR) for reperfusion. If ACD ("active compression decompression")-CPR is combined with a specific ventilatory valve ("inspiratory impedance threshold device", ITD) which does not allow passive inspiration, survival rate after cardiac arrest is increased for up to 24 h. Such a device facilitates an increase in venous return to the heart during decompression of the thorax. High-dose adrenalin for intrahospital CPR in children is not associated with better survival but with worse outcome. Comparison of an emergency medical service (EMS) system from U.K. with paramedics and a physician-staffed German EMS system demonstrated that survival rate following prehospital cardiac arrest is markedly increased with doctors on board. The European multicentre trial comparing vasopressin vs. adrenalin as first vasopressor during CPR in 1219 patients did not reveal any differences between both groups. In subgroup analyses of patients with asystoly and prolonged CPR, vasopressin was superior without being associated with a benefit on neurological outcome. Further subgroup analyses revealed beneficial effects of amiodarone and thrombolysis during CPR. Thrombolysis during CPR apears to be associated with an increased rate of haemodynamic stabilisation without increased risk of bleeding complications. In a very clear advisory statement, the "International Liaison Committee on Resuscitation" (ILCOR) has recommended mild therapeutic hypothermia (i. e., cooling of cardiac arrest victims to 32 - 34 degrees C central body temperature for 12 - 24 h following cardiac arrest of cardiac etiology) not only for unconciuous patients with ventricular fibrillation as initial prehospital rhythm, but also for all other adult patients (other rhythms, intrahospital CPR) following cardiac arrest. In randomised controlled clinical trials, this therapy has markedly improved survival rate and neurological outcome. Such therapeutic cooling can be initiated nearly everywhere and with simple methods - like the infusion of ice-cold cristalloid solutions.

Cardiopulmonary Resuscitation↗
PubMed1997

[Relationship between distortion product otoacoustic emissions and pure tone thresholds in normal and hearing-impaired ears].

To establish clinical criteria for distortion product otoacoustic emissions (DPOAEs) in order to distinguish normal-hearing from hearing-impaired ears, DPOAEs were measured and evaluated in 325 normal and 291 cochlear-impaired human ears using an ILO92 Otoacoustic Emission Analyzer. The background noise level was too variational in each individual ear to ignore in DPOAE measurements. Therefore, the value of the difference between the DPOAE amplitude and the background noise level (DPOAE noise) was calculated and compared with the pure tone threshold at 1 kHz, 2 kHz and 4 kHz. It was difficult, however, to precisely separate normal-hearing and hearing impaired ears with DPOAE noise values because many normal ears presented small amplitudes of DPOAEs and some impaired ears showed high amplitudes. Therefore, cumulative distributions of sensitivity (normal hearing ears identified as normal hearing) and specificity (hearing impaired ears identified as hearing impaired) were constructed and used to calculate a cut off point for DPOAE-noise in order to separate normal hearing from hearing impaired ears. It is considered that the cut-off points (DPOAE noise values of 7.3 dB at 1 kHz, 10.3 dB at 2 kHz and 16.1 dB at 4 kHz) at which the false alarm rates (1 specificity: the rate of hearing impaired ears incorrectly identified as normal hearing) correspond to 5% can be useful for clinical evaluation of DPOAEs.

Adolescent↗
PubMed2000

Monitoring of isoflurane and desflurane breakdown: interfering gases and infrared detection.

OBJECTIVE: The reaction of isoflurane, enflurane or desflurane with dried CO2 absorbents produces carbon monixide (CO), a highly toxic gas which cannot be detected by gas monitors typically available in the operating room. Trifluoromethane (CHF3) is produced along with CO when this reaction occurs with isoflurane and desflurane, and can be detected by gas monitors. This study will determine the ability of a modified SAM module (Smart Anesthesia Multigas Module, GE/Marquette Medical Systems, Milwaukee, WI) to identify the presence of CHF3, and provide a clinically useful indirect warning of CO production. METHODS: Isoflurane (1.5%) and desflurane (7.5%) were reacted under clinical conditions with desiccated absorbents resulting in CO production. CO and CHF3 concentrations were measured using gas chromatography. The CHF3 concentrations measured by a modified SAM monitor were compared with the measurements obtained by gas chromatography. Alarm limits set on the SAM monitor were used to warn of the presence of CHF3. RESULTS: A concentration of 0.25% CHF3, as measured by the SAM monitor, corresponds to an average CO concentration of 780 ppm for isoflurane and 1700 ppm for desflurane. Lowering the threshold to 0.05% CHF3 would result in an average CO concentration of 155 ppm CO for isoflurane and 345 ppm CO for desflurane. CONCLUSIONS: We have shown that the SAM module is capable of measuring CHF3 due to anesthetic breakdown. With appropriate changes in the display programming and reference cell spectra the monitor would be able to provide an early warning of CO exposure, although the amount of CO would not be reported.

Anesthesia, General↗
PubMed1992

[Antithrombin ii in eclampsia: estimation of predictive value].

We have observed in our study that antithrombin III activity decreases very significatively in eclampsia (p < 0.0001). A level of 90% was defined as a threshold. All the rates which are under or equal to 90% have 78.3% as a positive predictive value and those over 90% have a 98.7% as a negative predictive value for the overcoming of eclampsia. We have concluded that the 90% antithrombin III activity represents the alarm level for over coming eclamptic crises. The determination of the antithrombin III activity must be systematically done in every hypertensive pregnancy with proteinuria.

Adult↗
PubMed2001

Using simulated neuronal cell models for detection of epileptic seizures in foramen ovale and scalp EEG.

OBJECTIVE: To demonstrate a novel approach for real-time and automatic detection of epileptic seizures in EEG recorded with foramen ovale (Fov) or scalp electrodes. METHODS: Our seizure detection method is based on simulated leaky integrate and fire units (LIFU), which are classical simple neuronal cell models. The LIFUs are connected to a signal preprocessing stage and increase their spiking rates in response to rhythmic and synchronous EEG signals as typically occur at the onset and during seizures. RESULTS: We analyzed 22 short-term (10+/-3 min) and 4 long-term (18+/-7 h) Fov or scalp EEGs of 10 patients with drug resistant partial epilepsy. Seizures (n=36) were marked by increases of the LIFUs spiking rates above a preset threshold. The durations of increased spiking rates due to seizures were always longer than 10 s (36+/-21 s) and allowed separation from artifacts, which caused only short durations (1.2+/-0.6 s) of high spiking rates. The LIFUs correctly detected all the seizures and produced no false alarms. In the long term Fov EEGs seizure detection occurred before the onset of clinical signs (41+/-22 s). CONCLUSIONS: By using simulated neuronal cell models it is possible to automatically detect epileptic seizures in scalp and Fov EEG with high sensitivity and specificity.

Action Potentials↗
PubMed2001

Mother-Offspring vocal recognition in northern fur seals is mutual but asymmetrical.

During the 4-month period of offspring dependence, northern fur seal, Callorhinus ursinus, mothers and pups use a well-developed multimodal recognition ability to routinely find one another within large and dense breeding aggregations. I studied the vocal/auditory aspect of this ability to look at operational differences between the two members of a recognition dyad. If parent-offspring conflict theory is applied to animal communication behaviour, we should expect unequal selective forces acting on parents and offspring. In northern fur seal maternal recognition dyads, I expected pups to expend more energy in the reunion process because they carry the greater burden of a failed reunion. Furthermore, in terms of signal detection theory, pups should have a lower rejection threshold (lower bias) than mothers. To address these questions, I conducted vocal playback experiments and behavioural observations on a natural population of northern fur seals in the Pribilof Islands, Alaska, U.S.A. Although playback results support mutual vocal recognition, pups were both more vocally responsive and made more recognition errors (i.e. false alarms). Behavioural observations, including search time, distance travelled, signalling behaviour and contact with nonoffspring show that pups expend more effort in the reunion process. These findings are consistent with expectations and begin to quantify how selection pressure on recognition behaviour can vary at different stages of development. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMedDate not supplied

Age-related prefrontal alterations during auditory memory.

Event-related potentials were recorded from young and elderly subjects while they performed a modified auditory Sternberg memory task. Aging was associated with a decrease in frontal activation, suggesting that prefrontal alterations may be central to age-related impairments in auditory working memory. Young subjects showed significant serial position effects electrophysiologically, while elderly subjects showed no recency effects for P3 latency and no serial position effects for N4 and SFN amplitude. This finding, in combination with increased false alarm rates in the elderly, suggest that the two group of subjects employed different cortico-limbic circuits to perform the task.

Acoustic Stimulation↗
PubMed2000

Epidemiological surveillance of Guillain-Barré syndrome in Sweden, 1996-1997. Network members of the Swedish GBS Epidemiology Study Group.

OBJECTIVES: To set up an epidemiological surveillance system of Guillain-Barré syndrome (GBS) in Sweden and to evaluate the pilot practice of the system for 2 years. MATERIAL AND METHODS: A network of neurologists reported incident patients with a GBS diagnosis among a general population of 4.5 million inhabitants in Sweden during 1996 1997. Historical GBS data from the national hospital in-patient registry were used for predicting incidences and controlling under-reporting. RESULTS: One hundred and seventeen cases were reported. No alarm signals were identified during the study period. A re-analysis of data in 1996 revealed: 1) a higher than expected incidence in the population aged below 40 years in January, and 2) 27% under-reporting mainly associated to one hospital and to GBS patients hospitalized outside neurological departments. Threshold values for GBS incidences among the general and selected populations were obtained from corrected data. CONCLUSION: - The Swedish Network for GBS Surveillance can provide immediate support for epidemiological evaluation of suspected outbreaks or increased GBS incidence.

Adult↗
PubMed2002

Word frequency and receiver operating characteristic curves in recognition memory: evidence for a dual-process interpretation.

Dual-process models of the word-frequency mirror effect posit that low-frequency words are recollected more often than high-frequency words, producing the hit rate differences in the word-frequency effect, whereas high-frequency words are more familiar, producing the false-alarm-rate differences. In this pair of experiments, the authors demonstrate that the analysis of receiver operating characteristic (ROC) curves provides critical information in support of this interpretation. Specifically, when participants were required to discriminate between studied nouns and their plurality reversed complements, the ROC curve was accurately described by a threshold model that is consistent with recollection-based recognition. Further, the plurality discrimination ROC curves showed characteristics consistent with the interpretation that participants recollected low-frequency items more than high-frequency items.

Association Learning↗
PubMed1992

Early detection of extravasation of radiographic contrast medium. Work in progress.

Microwave radiometry is a passive and noninvasive technique that allows quick detection of subcutaneous temperature changes. The feasibility of this technique for differentiating normal intravenous infusions of radiographic contrast medium from extravasations of contrast medium was tested in anesthetized dogs. Room-temperature and heated ionic and nonionic contrast media were administered at flow rates ranging from 0.2 to 9.9 mL/sec by means of a power injector. On the basis of these experiments, an algorithm to adjust for extravasation detection thresholds as a function of injection flow rates was developed. With this algorithm, results showed a false-positive rate of 0% at all infusion rates and false-negative rates of 2%, 2%, and 4% at pump speeds of 0.2, 1.0, and 9.9 mL/sec, respectively. The times of these extravasation "alarms" corresponded to maximum extravasated volumes, respectively, of 4, 6.5, and 8 mL. Microwave radiometry has clinical potential for early detection of extravasation of contrast medium administered with power injectors.

Algorithms↗
PubMed1995

Type testing of the Siemens Plessey electronic personal dosemeter.

This paper presents the results of a laboratory assessment of the performance of a new type of personal dosimeter, the Electronic Personal Dosemeter made by Siemens Plessey Controls Limited. Twenty pre-production dosimeters and a reader were purchased by Ontario Hydro for the assessment. Tests were performed on radiological performance, including reproducibility, accuracy, linearity, detection threshold, energy response, angular response, neutron response, and response time. There were also tests on the effects of a variety of environmental factors, such as temperature, humidity, pulsed magnetic and electric fields, low- and high-frequency electromagnetic fields, light exposure, drop impact, vibration, and splashing. Other characteristics that were tested were alarm volume, clip force, and battery life. The test results were compared with the relevant requirements of three standards: an Ontario Hydro standard for personal alarming dosimeters, an International Electrotechnical Commission draft standard for direct reading personal dose monitors, and an International Electrotechnical Commission standard for thermoluminescence dosimetry systems for personal monitoring. In general, the performance of the Electronic Personal Dosemeter was found to be quite acceptable: it met most of the relevant requirements of the three standards. However, the following deficiencies were found: slow response time; sensitivity to high-frequency electromagnetic fields; poor resistance to dropping; and an alarm that was not loud enough. In addition, the response of the electronic personal dosimeter to low-energy beta rays may be too low for some applications. Problems were experienced with the reliability of operation of the pre-production dosimeters used in these tests.

Beta Particles↗
PubMed2006

Little Egrets (Egretta garzetta) and trace-metal contamination in wetlands of China.

The rapidly developing Asian countries may face threatening environmental contamination, that however remains largely unassessed. We studied persistent trace elements in three wetlands, Poyang Lake, relatively unpolluted, and Tai Lake, and Pearl River Delta, selected as hotspots of pollution in Central China. We adopted as indicator the Little Egret, a widespread colonial waterbird, and during 1999 and 2000 we collected and analysed the same samples as for a parallel study we conducted in Pakistan, e.g. eggs, body feathers of chicks, prey spontaneously regurgitated by the chicks, and sediments at the areas most used by foraging egrets. The levels of trace-metals at our three study areas were similar, or within the range, of those found in the few other studies for East Asia, with few exceptions. The concentrations of the various elements were below the threshold that may affect the survival or reproduction of the birds, and even the highest concentrations relative to background, i.e. Se in eggs, and Hg in feathers at Pearl Delta, do not pose toxic hazards. In sediments, the levels of trace elements were lower than the critical levels assumed for contaminated soil, except for alarming high levels of As at Poyang. These results do not confirm our expectation, that Poyang was relatively uncontaminated, while Tai and Pearl were polluted. Although trace metal concentration differed significantly among the three study areas, these differences were minor and were not consistent among elements and samples. The bioaccumulation ratios from sediments through prey, feather and egg, were consistent with our previous findings for Pakistan. Only Hg exhibited high bioaccumulation, while Se and Zn had low accumulation, and the other elements no accumulation. This reasserts that feathers of predators such as egrets, may be more sensitive indicators of environmental contamination for the elements subject to bioaccumulation, whereas the sediments or the organisms low in the food chain are better indicators for the other elements.

Animals↗
PubMed1978

Response detection in respiration audiometry.

The respiration of ten adults with normal hearing was monitored to determine how well changes in respiration could be detected after auditory stimulation. Three judges used two methods of response scoring. The first was without knowledge of signal presentation, and the second was with knowledge of signal presentation. Judges detected the presence of respiratory responses not only during signal presentations (hits) but also during silent intervals (false alarms). Hits and false alarms co-varied in a manner predicted by the theory of signal detectability. A low false alarm rate could be purchased only at the expense of a low hit rate. The implications of this finding for the clinical efficacy of respiration audiometry are considered.

Acoustic Stimulation↗
PubMed2002

Parieto-occipital arteriovenous malformation.

BACKGROUND: Arteriovenous malformation (AVM) in the occipital lobe has been known to cause visual symptoms and headaches. Arteriovenous malformation is a congenital anomaly that consists of abnormal arteries and veins without the presence of a capillary bed. The majority of patients initially manifest intracranial hemorrhage, while others manifest symptoms of seizures, headaches, and progressive neurological deficits. CASE REPORTS: A 45-year-old man was referred for a baseline threshold visual field before neurosurgery for his arteriovenous malformation. The patient's medical history included seizures with visual aura. The seizures were originally attributed to alcohol withdrawal; later, he was diagnosed with a right parietooccipital AVM. Optometric examination revealed an incomplete left inferior homonymous quadranopsia. He subsequently had the embolization and resection procedures for his AVM. Seizures and visual aura symptoms terminated after AVM surgery; the visual field defect increased slightly in extent. Two additional cases are presented to highlight some common characteristics-as well as the variability-in cerebral AVMs. The second case involves a 47-year-old man with a history of left frontal lobe AVM resection 7 years earlier and headaches. The third case is that of a 60-year-old man with a large left parietal lobe AVM with seizures who is anticipating neurosurgery. CONCLUSION: Clinical differentiation of migraine from arteriovenous malformation is often regarded as difficult, since both conditions may manifest similar features of visual aura, with or without headaches. Early diagnosis and treatment of AVM may reduce the risk of serious complications. When a patient manifests alarming headaches with or without visual aura, neuro-imaging workup is warranted to rule out sinister causes.

Cerebral Angiography↗
PubMed2001

Comparison between visual and passive acoustic detection of finless porpoises in the Yangtze River, China.

Recently, sonar signals and other sounds produced by cetaceans have been used for acoustic detection of individuals and groups in the wild. However, the detection probability ascertained by concomitant visual survey has not been demonstrated extensively. The finless porpoises (Neophocaena phocaenoides) have narrow band and high-frequency sonar signals, which are distinctive from background noises. Underwater sound monitoring with hydrophones (B&K8103) placed along the sides of a research vessel, concurrent with visual observations was conducted in the Yangtze River from Wuhan to Poyang Lake in 1998 in China. The peak to peak detection threshold was set at 133 dB re 1 ,EPa. With this threshold level, porpoises could be detected reliably within 300 m of the hydrophone. In a total of 774-km cruise, 588 finless porpoises were sighted by visual observation and 44 ,864 ultrasonic pulses were recorded by the acoustical observation system. The acoustic monitoring system could detect the presence of the finless porpoises 82% of the time. A false alarm in the system occurred with a frequency of 0.9%. The high-frequency acoustical observation is suggested as an effective method for field surveys of small cetaceans, which produce high-frequency sonar signals.

Animals↗
PubMed1993

Comparison of four techniques for recognition of ventricular fibrillation from the surface ECG.

Four ventricular fibrillation (VF) detection techniques were assessed using recordings of VF to evaluate sensitivity and VF-like recordings to evaluate specificity. The recordings were obtained from Coronary Care Unit patients. The techniques were: threshold crossing intervals (TCI); peaks in the autocorrelation function (ACF); signal content outside the mean frequency (VF-filter); and signal spectrum shape (spectrum). Using 70 extracts, each 4 s long, from VF recordings, the VF filter achieved a sensitivity of 77 per cent; the ACF, TCI and spectrum algorithms had sensitivities of 67, 53 and 46 per cent, respectively. Susceptibility to false alarms was assessed using 40 extracts from VF-like recordings. The TCI algorithm was the most specific (93 per cent), while the spectrum, VF filter and ACF algorithms had specificities of 72, 55 and 38 per cent, respectively. The TCI algorithm achieved overall sensitivity of 93 per cent and specificity of 60 per cent. The spectrum, VF filter and ACF algorithms had overall sensitivities of 80, 93 and 87 per cent, and overall specificities of 60, 20 and 0 per cent, respectively.

Algorithms↗