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PubMed1984

Effects of two benzodiazepines on the speed and accuracy of perceptual-motor performance in the elderly.

The daytime performance efficiency of 12 elderly subjects of average age 81.5 years (range 75-96 years) was examined in a cross-over study following lormetazepam 1 mg, nitrazepam 5 mg, and placebo capsules nightly for 7 nights. Performance was assessed on the Gibson spiral maze, and a reciprocal tapping task. In both tasks the speed and the accuracy of performance were independently measured. Performance testing sessions were conducted on the morning following the first, and the morning following the seventh dose of each of the three experimental treatments. Performance on the Gibson spiral maze showed no significant effect of either of the active drugs. On the reciprocal tapping task, speed was similarly unaffected by both drugs. However, while neither drug significantly affected overall accuracy after the first dose, nitrazepam but not lormetazepam significantly impaired overall accuracy after seven consecutive doses. This difference between nitrazepam and lormetazepam was significant. Further analyses showed nitrazepam consistently to be associated with impaired accuracy at both intermediate and high levels of task complexity. Lormetazepam, on the other hand, was associated with impairment only at the highest level of task complexity. The overall pattern of impairment associated with nitrazepam, but not with lormetazepam, was consistent with drug accumulation.

Aged↗
PubMed1996

The relative contribution of retinal and extraretinal signals in determining the accuracy of reaching movements in normal subjects and a deafferented patient.

This experiment investigated the relative extent to which different signals from the visuo-oculomotor system are used to improve accuracy of arm movements. Different visuo-oculomotor conditions were used to produce various retinal and extraretinal signals leading to a similar target amplitude: (a) fixating a central target while pointing to a peripheral visual target, (b) tracking a target through smooth pursuit movement and then pointing to the target when its excursion ceased, and (c) pointing to a target reached previously by a saccadic eye movement. The experiment was performed with a deafferented subject and control subjects. For the deafferented patient, the absence of proprioception prevented any comparison between internal representations of target and limb (through proprioception) positions during the arm movement. The deafferented patient's endpoint therefore provided a good estimate of the accuracy of the target coordinates used by the arm motor system. The deafferented subject showed relatively good accuracy by producing a saccade prior to the pointing, but large overshooting in the fixation condition and undershooting in the pursuit condition. The results suggest that the deafferented subject does use oculomotor signals to program arm movement and that signals associated with fast movements of the eyes are better for pointing accuracy than slow ramp movements. The inaccuracy of the deafferented subject when no eye movement is allowed (the condition in which the controls were the most accurate) suggests that, in this condition, a proprioceptive map is involved in which both the target and the arm are represented.

Adult↗
PubMed1982

Participation of the cerebellar dentate nucleus in the control of a goal-directed movement in monkeys. Effects of reversible or permanent dentate lesion on the duration and accuracy of a pointing response.

Experiments carried out on seven adult baboons were addressed at specifying the participation of the cerebellar dentate nucleus (DN) in the control of duration and accuracy of a goal-directed movement. The visuo-motor task used in this experiment involved trained pointing movement towards stationary target. The monkeys trained to point with the index finger to a target light were required to perform stereotyped movements of constant amplitude and direction, or movements with variable amplitude and direction. Duration of response execution was measured by movement time and accuracy by terminal spatial errors. We analysed the effects of excluding the DN on the arm ipsilateral or contralateral to the partially inactivated nucleus. Two techniques have been used to impair the DN activity: in three monkeys the structure was reversibly cooled with a chronically implanted thermode; in four others partial electrolytic destruction of the DN was performed. In the arm ipsilateral to the lesioned DN we observed modifications of movement times, appearance of systematic errors with increased dispersion. Contralateral effects were restricted to movement times. Changes in movement times and spatial errors were studied over time (4 months) in permanently lesioned animals. Only the spatial dispersion presented a total recovery. These data show that the DN is concerned with the control of speed and accuracy during the execution of visually triggered movements in monkeys. Moreover comparison of results concerning ipsilateral and contralateral effects of DN dysfunction on movement times and errors, and evidence of different time course of recovery in these variables, suggest a differential control exerted by the DN on speed and accuracy of goal directed movements.

Animals↗
PubMed1980

Translational accuracy enhanced in vitro by (p)ppGpp.

The effect of (p)ppGpp on the accuracy of translation in vitro was studied with a system that has a missense error frequency similar to that of living bacteria. When poly (U) is translated, limitation of the system in Phe increases the Leu missense error frequency. The introduction of (p)ppGpp to the Phe-limited mixtures reduces significantly the missense errors as well as reduces the rate of translation. The introduction of (p)ppGpp to a full system has no effect on the accuracy of translation but does reduce its rate. The effects of (p)ppGpp on rate and accuracy of translation can be simulated in part by other inhibitors of translation such as GDPCP, fusidic acid and tetracycline. Furthermore, the presence of ppGpp or GDPCP in a Phe-limited system leads to an accumulation of Phe-tRNA, while a Phe-limited system that contains only GTP has negligibly small concentrations of Phe-tRNA. We conclude that one way in which (p)ppGpp improves the accuracy of translation is by permitting the system to maintain a favorable Phe-tRNA/Leu-tRNA ratio.

Cell-Free System↗
PubMed1989

Determinants of diagnostic accuracy in pulmonary scintigraphy for pulmonary capillary protein leak associated with adult respiratory distress syndrome (ARDS): a technical note.

Radionuclide assessment of pulmonary capillary protein leak using [99mTc] human serum albumin (99mTc-HSA) was first reported from our laboratory. In this study we investigated the impact of 1) sampling time post tracer injection, and 2) lung region assignment, on diagnostic accuracy between 2 groups (control n = 20 and ARDS n = 20). Each patient received 370 MBq 99mTc-HSA i.v. and was imaged for 45 min. The slope index (SI) [change in lung: heart activity ratio/min] was calculated from 11 computer assigned lung regions for intervals of 5-15 (early [E]) and 15-45 (late [L]) min. The diagnostic accuracy of E vs L SI calculations for the 11 regions was evaluated by stepwise logistic regression. E SI data and L SI data from the lower 1/3 of the lung did not achieve significance for inclusion in the discriminant model (P less than 0.05). In the nine remaining regions L SI was significant. Optimal discrimination was achieved from L SI data obtained from a region confined to the lateral half of the mid 3rd of the lung field (sensitivity 81%, specificity 85%, accuracy 83%). The results confirm that: 1) a late (15-45 min) sampling period and 2) proper region assignment are necessary to maximize accuracy of this technique.

Adult↗
PubMed1977

The functional independence of response latency and accuracy: implications for the concept of conceptual tempo.

Kagan (1965a) developed the concepts of impulsive and reflective cognitive styles (conceptual tempo) to add a new dimension to the understanding and assessment of human intelligence. Although latency (the principal component of conceptual tempo) is negatively correlated with academic performance, it may not be necessary to modify latency in order to modify accuracy.. With 40 disadvantaged preschool children, it was found that reinforcing long latencies in choice tasks did not increase accuracy and vice versa, and that reinforcing both long latencies and accuracy was no more effective than reinforcing accuracy alone. These data were used to question the usefulness of the construct of conceptual tempo.

Achievement↗
PubMed1991

EEG versus MEG localization accuracy: theory and experiment.

We first review the theoretical and computer modelling studies concerning localization accuracy of EEG and MEG, both separately and together; the source is here a dipole. The results show that, of the three causes of localization errors, noise and head modelling errors have about the same effect on EEG and MEG localization accuracies, while the results for measurement placement errors are inconclusive. Thus, these results to date show no significant superiority of MEG over EEG localization accuracy. Secondly, we review the experimental findings, where there are again localization accuracy studies of EEG and MEG both separately and together. The most significant EEG-only study was due to dipoles implanted in the heads of patients, and produced an average localization error of 20 mm. Various MEG-only studies gave an average error of 2-3 mm in saline spheres and 4-8 mm in saline-filled skulls. In the one study where EEG and MEG localization were directly compared in the same actual head, again using dipoles implanted in patients, the average EEG and MEG errors of localization were 10 and 8 mm respectively. The MEG error was later confirmed by a similar (but MEG-only) experiment in another study, using a more elaborate MEG system. In summary, both theory and experiment suggests that the MEG offers no significant advantage over the EEG in the task of localizing a dipole source. The main use of the MEG, therefore, should be based on the proven feature that the MEG signal from a radial source is highly suppressed, allowing it to complement the EEG in selecting between competing source configurations.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1991

The relative accuracies of two automated noninvasive arterial pressure measurement devices.

We compared the accuracies of two types of noninvasive blood pressure devices. Thirty-two patients requiring an intraarterial catheter for anesthetic management underwent simultaneous monitoring with Dinamap 1846SX and Ohmeda Finapres 3700 devices. For the first 10 minutes of recording, new Dinamap determinations were performed every 60 seconds; subsequent recordings were made at 3-minute intervals. Data were obtained at the time of new Dinamap readings, and twice between new readings to approximate the real-time performance of the two monitors. We defined superior accuracy as a statistically significant difference in mean absolute error greater than 5 mm Hg. With these criteria, pooled data from all patients revealed no difference in performance, even in real time. Pooled data can be misleading since there was a significant amount of variation in accuracy for both monitors. Therefore, we used nonparametric analysis to determine how many individual patients were monitored better by either device. When we compared only data from new Dinamap readings, the Finapres monitor showed superior performance for systolic readings in 13 patients, versus 6 patients for the Dinamap (P less than 0.05, chi-square test). Similar analysis for diastolic and mean pressure performance did not reach statistical significance. However, in real time, the Finapres unit monitored more patients more accurately for systolic (14 Finapres versus 3 Dinamap), diastolic (11 Finapres versus 3 Dinamap), and mean (10 Finapres versus 3 Dinamap) pressure determinations. The magnitude of these differences were, however, less dramatic than expected. This was probably due to stabilization of arterial pressure during the anesthetic, which minimized the error due to intermittent sampling. We conclude that continuous Finapres readings and new Dinamap determinations are equally accurate for diastolic and mean arterial pressures. The accuracy of Finapres appears to be slightly superior for systolic pressure. The intermittent sampling of oscillometric devices compromises their performance relative to the Finapres in many, but not all, cases.

Adult↗
PubMed1993

Accuracy and cross-sensitivity of 10 different anesthetic gas monitors.

OBJECTIVE: The objective of this study was to test the accuracy and cross-sensitivity of commercially available anesthetic gas monitors. METHODS: Using gas chromatography (GC) as a reference method, the accuracy, cross-sensitivity, and ability to recognize an erroneously selected agent were determined in the following 10 monitors for volatile anesthetics: Datex Capnomac Ultima-S, Datex Capnomac, Ohmeda 5330 agent monitor, Iris Dräger, Andros Dräger PM 8020 (all monochromatic, infrared analyzers), Nellcor N-2500E, Criticare POET II, Irina Dräger (all polychromatic, infrared analyzers), Siemens Servo Gas Monitor 120 (a piezoelectric analyzer), and Brüel & Kajer Type 1304 (a photoacoustic analyzer). Accuracy was determined at 0.5, 1, 2, and 4 times the minimal alveolar concentration (MAC) of either halothane or isoflurane in oxygen (O2). The cross-sensitivity tests were performed with 70 vol% nitrous oxide in O2, 5 vol% carbon dioxide in O2, 0.032 vol% alcohol in O2, and 70% water vapor in O2. The photoacoustic analyzer showed a higher accuracy for isoflurane than the polychromatic infrared monitors. The greatest inaccuracy with isoflurane was found in the Iris Dräger monitor, which had a maximal bias percentage by volume (vol%) of 0.09 at 0.5 MAC. (This bias was within the manufacturer's specified tolerance of +/- 0.1 vol% or 10% relative difference of reading, whichever is greater.) Irina Dräger was the most accurate analyzer with halothane (mean % bias [relative %] +/- SD, 0.9 +/- 2.0%). The greatest bias with halothane was found in the monochromatic infrared analyzers, with a maximal % bias at 0.5 MAC of 50.3% of the GC reading (12.4% with a new inner Nafion tube) found in the Datex Ultima monitor. The Siemens gas monitor showed a cross-sensitivity for water vapor (-0.248 vol%). The monochromatic infrared analyzers showed a small sensitivity to alcohol (additional deviation of 0.011 to 0.147 vol% at 2 MAC isoflurane) but no sensitivity to nitrous oxide. No cross-sensitivity was found in the polychromatic infrared and photoacoustic analyzers. An incorrect selection of anesthetic agent when using a monochromatic infrared analyzer can be fatal; for example, when using halothane and selecting isoflurane the values measured by the Datex Capnomac monitor were nearly 6 times: below the actual value (i.e., 1 vol% "isoflurane" on the display = 6 vol% halothane in reality). CONCLUSIONS: The photoacoustic measurement principle is more accurate than the other methods, although the polychromatic infrared analyzers are safer because they detect erroneously selected agents.

Anesthesia, Inhalation↗
PubMed1989

A graphic representation of projection accuracy.

The author examines "the problem of measuring projection accuracy. Experience with applying the accuracy measure 'quality of prediction', as proposed by Keyfitz, leads the author to a critical evaluation and elaboration of this accuracy measure. Time series of prediction quality values may show a remarkable temporal instability, partly depending on the chosen bench mark, which seriously hinders interpretation. This interpretation problem may be solved by an easily applicable graphical solution, a convenient short-circuit device to assess a projection's accuracy without restrictions as to size of population or length of projection period." The concepts are illustrated with data used for population forecasts for the Netherlands during the 1970s. (SUMMARY IN FRE)

Demography↗
PubMed1990

Effects of video frame averaging, smoothing and edge enhancement on the accuracy and precision of quantitative coronary arteriography.

Digital analysis of cine film provides numerous options for altering images by frame averaging or filtering algorithms that either smooth or enhance edges. While these may subjectively enhance image quality, there is no uniformity in their use among laboratories and effects on quantitative coronary analysis may not be ideal. To determine which processing algorithms might help or hinder quantitative coronary arteriography, cine film images of precision drilled stenotic cylinders (0.83 to 1.83 nm diameter) implanted in dog coronary arteries were analyzed with and without such algorithms. Video frame averaging of 1 to 49 frames had no effect on measures of accuracy (mean differences) but precision (standard deviation of mean differences) was improved from 0.23 to 0.17 mm (p less than 0.05) with video averaging of greater than or equal to 25 frames. Edge enhancement filtering algorithms resulted in slight deterioration of accuracy and precision and smoothing filtering algorithms caused modest improvements in these parameters; however, these changes were not significantly different from unprocessed images. Using edge enhancement filtering algorithms, accuracy was significantly worse (-0.27 mm) compared to a smoothing filter enhancement algorithm (-0.08 mm, p less than 0.001). The combination of video averaging and smoothing algorithms had no additional beneficial effects. Thus, precision of quantitative coronary analysis of cine film can be optimized by appropriate video averaging. Edge enhancement filtering algorithms should be avoided whereas smoothing filter enhancement algorithms may improve accuracy.

Algorithms↗
PubMed1990

Accuracy of ultrasonic bladder volume measurement in children.

The accuracy of ultrasonography in assessing the bladder volume in 13 children with normal bladder contours was determined using the formula D x H x W (depth x height x width) with a mean error of 15.7%. This formula tends to overestimate the bladder volume in these patients. Multiplication by a correction factor of 0.9 yields a mean error of 11.5%. The accuracy of this evaluation is not dependent upon the bladder volume as the mean error was the same in those children whose bladder volume was either less than or greater than 150 cc. In addition, the accuracy of ultrasonography in assessing bladder volume was evaluated in 7 patients with an abnormal bladder contour (trabeculation, diverticula, etc.); mean error was 14.7%. In these 7 patients there was no predictable under or overestimation of bladder volume. In the children with abnormal bladder contours on ultrasound, the correction factor of 0.9 should not be used, as it does not add to the accuracy of the procedure in any individual patient. This technique is still valuable, however, in children with an abnormal bladder for it allows estimation of the extent of emptying without invasive catheterization.

Adolescent↗
PubMed1993

[The accuracy of holograms compared to other model measurements].

Because holograms are easy to deal with, and because their information content is especially high, they will potentially play a much larger role in the future. In this study plaster casts were placed in a measuring device fabricated in our department, measured by means of a laser beam, and then the accuracy of these measurements was compared to hologram measurements taken by means of a sliding caliper. The result was that the computer-guided hologram measurements evidenced no significant differences with the measurements with a laser beam. The hologram measurements, which are regarded as having an accuracy of 0.182 mm, should therefore be significantly superior to sliding caliper measurements. When measuring the mesiodistal width of teeth, the caliper yields a pseudo-accuracy which doesn't correspond to the factual conditions. When defining the Z-coordinates, the sliding caliper's measuring deficiencies are easily circumvented, but this does not automatically imply a higher degree of accuracy.

Dental Occlusion↗
PubMed1989

Suturing techniques of individual surgeons--differences in accuracy and mechanics.

The suturing techniques of fifteen surgeons with similar surgical experience were evaluated with respect to pinpoint accuracy and the force produced while suturing. Subjects were randomly selected from a group of surgeons whose surgical experience ranged from five to six years. Accuracy was determined by the deviated distance between the needle exit and the designated exit. Force was expressed as torques (F) loaded on a needle holder, and included the derivatives (dF/dt) and integrals (IF). Suturing times (T) were also measured. Ten attempts at suturing were allowed, using each of the following two methods: 1) allowing adjustment by wavering the needle to improve accuracy, and 2) suturing without wavering the needle. The differences in technique, on an individual basis, were highly significant. The accuracy and the mechanics, including the maximum F, maximum dF/dt, IF, IF/T, and T, all had a p-value of less than 0.0001. The surgeons' ranks according to these variables were also concordant, the Kendall's coefficients of concordance (W) being 0.60 (p = 0.002) for suturing done without wavering and 0.56 (p = 0.005) for that done with wavering. It was concluded that the surgeons' skill in suturing techniques differed significantly among individuals and that the surgeons' ranks according to the variables were also concordant. Thus, formal training in suturing techniques should be established as part of the training of all surgeons.

Clinical Competence↗
PubMed1995

Carbon dioxide analysers: accuracy, alarm limits and effects of interfering gases.

Six mainstream and twelve sidestream infrared carbon dioxide (CO2) analysers were tested for accuracy of the CO2 display value, alarm activation and the effects of nitrous oxide (N2O), oxygen (O2) and water vapour according to the ISO Draft International Standard (DIS)#9918. Mainstream analysers (M-type): Novametrix Capnogard 1265; Hewlett Packard HP M1166A (CO2-module HP M1016A); Datascope Passport; Marquette Tramscope 12; Nellcor Ultra Cap N-6000; Hellige Vicom-sm SMU 611/612 ETC. Sidestream analysers: Brüel & Kjaer Type 1304; Datex Capnomac II; Marquette MGA-AS; Datascope Multinex; Ohmeda 4700 OxiCap (all type S1: respiratory cycles not demanded); Biochem BCI 9000; Bruker BCI 9100; Dräger Capnodig and PM 8020; Criticare Poet II; Hellige Vicom-sm SMU 611/612 A-GAS (all type S2: respiratory cycles demanded). The investigations were performed with premixed test gases (2.5, 5, 10 vol%, error < or = 1% rel.). Humidification (37 degrees C) of gases were generated by a Dräger Aquapor. Respiratory cycles were simulated by manually activated valves. All monitors complied with the tolerated accuracy bias in CO2 reading (< or = 12% or 4 mmHg of actual test gas value) for wet and dry test gases at all concentrations, except that the Marquette MGA-AS exceeded this accuracy limit with wet gases at 5 and 10 vol% CO2. Water condensed in the metal airway adapter of the HP M1166A at 37 degrees C gas temperature but not at 30 degrees C. The Servomex 2500 (nonclinical reference monitor), Passport (M-type), Multinex (S1-type) and Poet II (S2-type) showed the least bias for dry and wet gases. Nitrous oxide and O2 had practically no effect on the Capnodig and the errors in the others were max. 3.4 mmHg, still within the tolerated bias in the DIS (same as above). The difference between the display reading at alarm activation and the set point was in all monitors (except in the Capnodig: bias 1.75 mmHg at 5 vol% CO2) below the tolerated limit of the DIS (difference < or = 0.2 vol%). The authors conclude that the tested monitors are safe for clinical used (except those failing the DIS limits). The accuracy of the CO2-reading (average of mean absolute bias) is better in the M-type than in the S1- or S2-type analysers although no statistical (nor clinical) significant differences could be detected. Most manufacturers work with stricter limits than those proposed by the DIS.

Blood Gas Analysis↗
PubMed1995

Improvement of the accuracy of references in the Canadian Journal of Anaesthesia.

A previous study indicated that there were many citation errors in the Canadian Journal of Anaesthesia. After this report, editors of the Journal requested any contributors, whose papers were accepted for publication, to verify the accuracy of reference citation by including a photocopy of the first page of each reference. The present study examined if the accuracy of the reference list had improved. We compared citation errors between volumes of 1990 and 1994. One hundred references from each year's publication were randomly selected. After citations of nonjournal articles were excluded, the remaining 190 citations were carefully scrutinized. Authors' names, article title, journal title, volume number, page numbers, and year were examined in each selected reference. A reference was deemed correct if each element of the citation was identical to its source. Of the examined references, 48% and 22% contained one or more errors in 1990 and 1994, respectively. Errors in the title and author field of citation were most common in the either of the two years, occurring in about 70% of the references which contained some errors. Citation errors in Canadian Journal of Anaesthesia were considerably improved after the request to verify citation accuracy. Although this check-system probably contributes to the improvement of accuracy of reference citation, the rate of citation errors remains high. We believe that contributors' efforts will enhance the value of the journal.

Anesthesiology↗
PubMed2000

Accuracy of carboxyhemoglobin dilution method for the measurement of circulating blood volume.

PURPOSE: The management of circulating blood volume (BVc) is crucial in intensive care unit (ICU) patients. The purpose of this study was to verify the accuracy and precision of the carbon monoxide-labeled hemoglobin (CO-Hb) dilution method (CO method) by comparing it with the 51Cr-labeled erythrocyte dilution method (51Cr method) for the measurement of BVc. METHODS: A prospective study was performed in 18 patients who underwent coronary artery bypass grafting (CABG) under mild hypothermic cardiopulmonary bypass (CPB). The BVc was measured by both the CO method and the 51Cr method at 24 hr after ICU admission in order to verify the accuracy and precision of the CO method. Paired data were assessed in absolute terms, and percentage errors were calculated by the degree of agreement. RESULTS: Small mean differences and standard deviations between the CO method and the 51Cr method (-70.2 +/-184.8 mL) and small percentage errors (-0.49+/-1.29%) indicated the accuracy and precision of the CO method, and a close correlation was observed (r = 0.97). CONCLUSION: The CO method can measure BVc with a similar degree of accuracy as the 51Cr method. It is simple, repeatable and safe without the risk of exposure to radioactivity in the ICU.

Blood Volume↗
PubMedDate not supplied

Completeness and accuracy of the drug treatment reporting system in Dublin, Ireland.

BACKGROUND: The National Drug Treatment Reporting System (NDTRS) is the Irish treated-drug misuse surveillance system. AIM: To measure completeness and accuracy of the NDTRS. METHODS: Cross-sectional survey of clinical records and matching NDTRS reporting forms of a random sample of 520 clients attending 4 Dublin treatment centres. Using clients' clinical records as the gold standard, system completeness (proportion of sample reported to the NDTRS) and accuracy of selected variables (proportion of reported clients' information on the NDTRS that matched clinical record information) were measured. RESULTS: 452/520 (87%) selected records were retrieved. The NDTRS was only 61.1% (95% CI 56.5-65-5) complete; completeness differed across treatment centres (21.8%-85.6%, p < 0.0001) and was greater for new and returning clients than for continuing clients (81.7% versus 53.9% respectively, p < 0.0001). Problems were identified with the accuracy of some key variables. CONCLUSIONS: Urgent actions have been taken to improve the completeness and accuracy of the reporting system.

Cross-Sectional Studies↗