Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Error Sources”

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

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

At least 1,801 records · Page 100Linked to original sources
PubMed1995

A quality study of a computerized medical birth registry.

Processed by a computerized medical birth registry system, the birth records of 20,103 deliveries, from February 1992 to February 1993, were digitized with medium registry. From January 1, to February 28, 1993, the original records (n = 2,840 cases) of all 10 collaborative hospitals were requested for assessment of the data quality. Thirty-six items were scored, data of poor quality was found in 8 items; acceptable quality in 4 items; and good quality in 28 items. The feasibility of data transfer by floppy disc and per modem was evaluated. This registry system had shortened data processing time effectively and improved mutual feedback between data center and delivery units. Errors resulting from technical faults originating in preparation of the data for computerizing at hospital level could be effectively reduced. The validity of diagnosis remained as the major source of errors.

Birth Certificates↗
PubMed1992

Measurement of plasma volume in neonates.

There is no reliable and safe method for measuring plasma volume in ill newborn infants. We describe an adaptation of the dye dilution technique using indocyanine green as the plasma label, which can be used in the sickest and smallest of infants with the minimum of disturbance. To avoid the need to take large volumes of blood from the infant, samples were diluted 1:1 with distilled water and pooled adult sera was used to construct the dye dilution standard curves. Eighteen preterm and fullterm infants were studied on 30 occasions. The measured plasma volume ranged between 21.4 and 106 ml/kg. Paired measurements were performed within 30-90 minutes of each other in seven infants. In five infants estimations of plasma volume were made shortly before and 30 minutes after the infusion of a known quantity of plasma. In eight out of 12 infants who had two measurements made there was close agreement between the second measured volume and the first measured volume, taking into account how much plasma had been given to or taken from the infant between the two measurements. The error ranged from 0.2 to 5.2 ml and the plasma recovery error ranged from -2.9% to +4.7%. In the remaining four infants the errors ranged from 2.1 to 9.5 ml and -14.2% to +8.8%. Errors in the measurement of plasma volume may arise as the result of sampling too early before full mixing of the dye has occurred, and there is a potential error in the measurement due to the distribution of albumin in the extracellular space in sick infants resulting in an overestimation of the plasma volume. Proposals for reducing sources of errors are discussed.

Blood Specimen Collection↗
PubMed1992

Error in radiology: classification and lessons in 182 cases presented at a problem case conference.

The authors review and classify errors in 182 cases that were presented at problem case conferences between August 1986 and October 1990. Errors were classified by means of a system developed 20 years ago and by means of a system developed within the past several years. The authors found that sources of error have changed very little. Errors usually involved failure to consult old radiologic studies or reports, limitations in imaging technique, acquisition of inaccurate or incomplete clinical history, location of a lesion outside the area of interest on an image, lack of knowledge, failure to continue to search for abnormalities after the first abnormality was found, and failure to recognize a normal biologic variant. Errors included 126 perceptual errors (64 false-negative, 15 false-positive, and 47 misclassification errors) and 56 mishaps, including 38 complications and 18 communication errors. In seven cases nonperception errors occurred because established departmental routines were not followed, and in nine cases a new departmental routine was established after a complication occurred. Departmental policy exerts less effect on perception and interpretation errors.

Diagnostic Errors↗
PubMedDate not supplied

Data quality of a computerized medical birth registry.

Processed by a computerized medical birth registry system, the birth records of 20,103 deliveries, from February 1992 to February 1993, were digitized with medium registry. From 1 January to 28 February 1993, the original records (n = 2840 cases) of all 10 collaborative hospitals were requested for assessment of data quality. Thirty-six items were scored, data of poor quality was found in eight; acceptable quality in four; and good quality in 28. The feasibility of data transfer by floppy disc and per modem was evaluated. This registry system had effectively shortened data processing time and improved mutual feedback between the data centre and the delivery units. Errors resulting from technical faults originating in the preparation of data for computerization at hospital level could be effectively reduced. The validity of diagnosis remained as the major source of errors.

Birth Certificates↗
PubMed1998

A study of the accuracy of corneal reflection pupillometers.

We studied the accuracy of nine corneal reflection pupillometers made by three manufacturers, because, at the time of investigation, we could not find any information about their accuracy. For this purpose two steel balls separated by spacer bars, were positioned to simulate nominal inter-pupillary distance (PD) measurements of 55, 60, 65 and 70 mm. Ten measurements of each 'PD' for distance vision, were made by two experienced observers, with each instrument. We found that interobserver differences in measurement were clinically insignificant most of the time, although some data sets were significantly different statistically. The most consistent and accurate measurements of PD were achieved with PD 65 mm. The average error in mean value of the measurements for all PD's, was 2.3 mm, and the average of the standard deviation in our measurements, was 0.26 mm. Significant sources of error were poor eye relief in all instruments evaluated, as well as friction in the scale adjustment mechanism in some instruments. Our findings show that while a given pupillometer may be relied upon to give consistent readings (within the limits of clinically acceptable error), its accuracy should be checked periodically, especially for very small and very large PD measurements.

Humans↗
PubMed1976

[Possible error in interpretation of liquor enzyme activities as demonstrated on the example of lactate dehydrogenase and cholinesterase].

If examinations of the liquor are to give an insight into the metabolic condition of the brain, then it is necessary for all sources of error to be removed. The use fo exact methods requires that the liquor be free of major pleocytosis. In vitro examinations showed that additions of blood caused the activity of LDH to be doubled within thirty minutes, while that of cholinesterase even increased sixfold. It is especially after craniocerebral injuries that extra care must be taken to insure that the liquor used is as clear as water.

Brain Concussion↗
PubMed1979

Biologically active luteinizing hormone (LH) in plasma. III. Validation of the in vitro bioassay when applied to male plasma and the possible role of steroidal precursors.

An in vitro bioassay method for measuring LH activity was applied to male plasma. This method is based on the specific testosterone response to LH activity by interstitial cells from mouse testes. In contrast to assays conducted on female plasma, non-parallel response lines were obtained between serial dilutions of untreated male plasma and the International Reference Preparation for Human Pituitary Gonadotrophins FSH and LH/ICSH) for bioassay (code no. 69/104). In an attempt to eliminate this source of error, which would invalidate the assays, plasma was subjected to either ether extraction or charcoal adsorption prior to assay. While ether extraction was ineffective, charcoal treatment eliminated the source of non-parallelism. Evidence is presented indicating that the inclusion of a charcoal pre-treatment step provides an assay method for LH which fulfils the recognized criteria of reliability when applied to male plasma. An investigation of the likely causes of non-parallelism was undertaken by incubating mouse interstitial cells with various steroids and steroid sulphates at concentrations likely to be present in plasma. While most of the presumed precursors of testosterone were converted to testosterone, steroid sulphates (dehydroepiandrosterone sulphate and pregnenolone sulphate) at high concentrations as present in male plasma were the most active compounds in forming testosterone. However, the amount of testosterone produced from these precursors under controlled conditions was insufficient to account entirely for the deviation from parallelism observed with male plasma. Hence, the non-parallelism observed with untreated plasma samples cannot be entirely explained by the presence of steroidal testosterone precursors in male plasma.

Adsorption↗
PubMed1983

Validity and reliability of trends in suicide statistics.

For a number of reasons, suicide is under-reported and the reliability of official rates is subject to error through variations in defining and reporting cases, the kind of inaccuracy encountered when ascertaining cases in studies of mortality from any cause. Nevertheless, the evidence from studies designed to see whether these sources of error invalidate the differences reported between cultural and social groups indicates that they are of a random nature, at least to an extent that allows epidemiologists to compare rates between countries and districts within them, between demographic groups, and over periods of time. The accuracy and hence the value of official suicide statistics has been questioned in recent years to an extent that has led some authorities to dismiss their usefulness in epidemiological research. In England and Wales, a decision as to whether an unexpected or violent death is a suicide or not is normally made at a coroner's inquest; similar, but by no means identical procedures are followed in other developed countries. Cases defined and ascertained in this way are the usual source of national suicide statistics. Indeed, it may be claimed that the medical and post-mortem inquiry together with the evidence of witnesses on the psychological and social circumstances relating to the act, entail a more thorough investigation into this cause of death than is usual in compiling the statistics of deaths from other causes. Consider by contrast the General Registrar Office enquiry into the accuracy of reporting other causes of death (1). When, for example, deaths from cancer of the lung are registered before holding a post-mortem and the cause of death is later checked by a pathologist, the net error is about 16%. The conclusions drawn from official cancer statistics, however, are not seriously questioned. It is thus reasonable to expect suicide statistics, despite inaccuracies, also to be of heuristic value particularly as over-reporting is negligible, and it is only under-reporting, not a matter in dispute, that need be considered. Studies of under-reporting of suicide include those done in England and Wales (2), Scotland (3), and in Ireland where McCarthy & Walsh (4) examined coroners' case records in Dublin using clinical criteria to assess the probability of suicide. Though their revised rate was considerably higher than the official one, the Irish rate is still exceptionally low when compared with other countries. Barraclough (5) confirmed by other means that the adjusted rate was still half that of England.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2004

A systems approach to error prevention in medicine.

Minimization of medical errors is at the core of all clinical medical practices. The first tenet of care is to do no harm. The enormous complexity of modern medical care has made error detection and management extremely difficult. Traditional deterministic methods of solving the "error issue" cannot cope with the huge number of potential errors that are possible. Systems thinking and approach to error reduction provides a different avenue for tackling this challenging dilemma. The intent of this article is to introduce a systems view of medical errors and to explain how it can provide new insights about dealing with massively complex organizations such as the healthcare system. Important features include an understanding of system relationships, sources of error, human components, optimization versus perfection in systems and the interrelationships between human and system processes.

Delivery of Health Care↗
PubMed2002

Influence of loading rate and cable migration on fiberoptic measurement of tendon force.

Several investigators have recently used fiberoptic cables to measure tendon forces in situ. The technique may be subject to significant error due to cable migration and differences in the loading rates used for calibration and those experienced during measurement. This in vitro study examined the impact of these potential sources of error on transducer accuracy. A fiberoptic cable was passed perpendicular to the fibers of four Achilles tendons in the mediolateral direction and each specimen was cyclically loaded to 1000 N. The influence of loading rate on transducer output was investigated by comparing results from tests conducted at 20, 200 and 1000 N/s. The effect of cable migration was examined by comparing the outputs obtained after displacing the cable one tendon width medially and laterally along its path in the tendon and then repeating the 200 N/s testing protocol. It was possible to obtain nonlinear specimen-specific relationships between the fiberoptic output and tendon force. Differences in loading rate resulted in root-mean-square (RMS) errors not larger than 17% maximum load. Hysteresis effects caused RMS errors smaller than 5% maximum load. Cable migration errors were less than 27%. The total RMS error due to the combined effects of loading rate difference and cable movement was less than 32%. Fiberoptic measurement of tendon force is attractive due to its low cost, easy implementation and comparable accuracy relative to other implantable force transducers. Although additional factors such as cable placement, edge artifacts due where the transducer exits the skin and non-uniform loading may also influence fiberoptic output, careful control of loading rate and transducer movement during calibration is imperative if maximum accuracy is to be achieved.

Achilles Tendon↗
PubMed1997

Pitfalls in estimating motion detector receptive field geometry.

A number of psychophysical investigations have used spatial-summation methods to estimate the receptive field (RF) geometry of motion detectors by exploring how psychophysical thresholds change with stimulus height and/or width. This approach is based on the idea that an observer's ability to detect motion direction is strongly determined by the relationship between the stimulus geometry (height and width) and the RF of the activated motion detectors. Our results show that previous estimates of RF geometry can depend significantly on stimulus position in the visual field as well as on the stimulus height-to-width ratio. The data further show that RF estimates depend on the stimulus in a manner that is inconsistent with basic predictions derived from current motion detector models. Hence previous estimates of height, width, and height-to-width ratios of motion detector RFs are inaccurate and unreliable. This inaccuracy/unreliability is attributed to a number of sources. These include incorrect fixed-parameter values in model fits, as well as the confounding of physiological spatial summation area through combined use of contrast thresholds and Gaussian-windowed stimuli. A third source of error is an asymmetric variation of spatiotemporal correlation in the stimulus as either its height or width is varied (and the other dimension held constant). Most importantly, a fourth source of unreliability is attributed to the existence of a nonlinear, nonmonotonic distribution of motion detectors in the visual field that has been previously described and is a natural result of visual anatomy.

Contrast Sensitivity↗
PubMed1989

Serum osmolality in alcohol ingestions: differences in availability among laboratories of teaching hospital, nonteaching hospital, and commercial facilities.

Freezing point depression osmometry is preferred over vapor pressure with ingestions of volatile substances. Sixty-six laboratories nationwide (23 teaching hospital, 22 nonteaching hospital, and 21 commercial facilities) were surveyed to determine the availability and use of these techniques. Overall, 80% conducted serum osmometry (teaching, 100%; nonteaching, 82%; commercial, 57%). Freezing point depression was the most common method used by all laboratories; however, 33% of commercial laboratories and 11% of nonteaching laboratories used vapor pressure exclusively. One half of all laboratory supervisors did not identify why one method was preferred. Only 3% identified vapor pressure as a possible source of error in ingestions of volatile substances. Most laboratories estimated that they were aware of the patient diagnosis less than 50% of the time. Because vapor pressure osmometry is a potential source of false negative results when estimating serum concentrations of volatile substances, clinicians treating patients who have ingested ethanol, ethylene glycol, isopropanol, or methanol need to be aware of the methodology used in their reference laboratories.

Alcohols↗
PubMed2005

Prevention of medication errors.

Medication error is the most frequent source of medical error that is associated with adverse events, and, in many cases, is preventable. Medication errors can occur at any step in the medication process. Medication error prevention and reduction begins with a systematic approach to their detection. An important approach to mitigating errors involves the reduction of variation in task performance using tested techniques and technologies from other industries. The most important component of error prevention and reduction is the proactive promotion of a safety culture by organizational leadership, with sustained education and support for users.

Humans↗
PubMed1998

Accuracy of dilution techniques for access flow measurement during hemodialysis.

Access flow is now widely measured by creating artificial recirculation with the dialysis lines reversed and using dilution methods that sense either ultrasound velocity, electrical impedance, optical, or thermal changes. This study identifies and quantifies factors that influence the accuracy of access flow measurements and recommends ways to reduce these errors. Two major sources of access flow measurement error are identified, arising firstly from the second pass of the indicator by recirculation through the cardiopulmonary system (cardiopulmonary recirculation, CPR), and secondly from changes in venous line blood flow (Qb) and vascular access flow induced by the pressure of venous bolus injections. These errors are considered from theory, by direct measurement of access flow in a sheep model, and by analysis of clinical data. Two extremes for the venous introduction of indicator can be considered in access flow measurements, a slow infusion, which perturbs neither the venous line flow nor access flow but increases the error attributable to the second pass of the indicator by recirculation through cardiopulmonary system, or rapid injection, which eases separation of the second pass of the indicator signal but generates changes in the venous flow and access flow. If CPR is not eliminated, the area added to that of the first pass of indicator ranges up to 40%. Good time resolution could permit the separation of the areas generated by the first and second passage of the indicator. In sheep experiments, injections of 5 or 10 mL into a venous port close to the vascular access caused Qb to change by 20% to 40%. Both the animal experiments and analysis of raw data collected during routine clinical dialysis showed that moving the injection site sufficiently far from the patient, before or into the venous bubble trap, reduced the increase in Qb to only approximately 5% during the critical time when the concentration curve is changing for most tubing brands (Baxter, Belco, Gambro, Hospal, Medisystem, and National Medical Care). Because of the smaller volume of the venous bubble chamber in Cobe tubing (Cobe, Centrysystem 3), this brand showed approximately a 20% increase in Qb. Moving the site of bolus injections to before the bubble trap in the sheep experiments also eliminated the influence of changes in access flow. An additional error in access flow measurement of 20% or more arises from the use of flow reading taken from pump setting rather than a measured flow. The discrepancy between the real flow and pump setting is attributable to needle size, vascular access conditions, or pump calibration. The results show that problems can be minimized by using a dual sensor system that retains the precise timing necessary for separation of access recirculation from CPR; by accurate measurement of dialyzer blood flow; by moving the site of injection to before the venous bubble trap, sufficiently far from the patient, and correcting for any remaining deviations in flow in the venous line concurrent with the dilution curve.

Animals↗
PubMed2003

Reducing prescribing error: competence, control, and culture.

Medication errors are probably the most prevalent form of medical error, and prescribing errors are the most important source of medication errors. In this article we suggest interventions are needed at three levels to improve prescribing: (1) improve the training, and test the competence, of prescribers; (2) control the environment in which prescribers perform in order to standardise it, have greater controls on riskier drugs, and use technology to provide decision support; and (3) change organisational cultures, which do not support the belief that prescribing is a complex, technical, act, and that it is important to get it right. Solutions involve overt acknowledgement of this by senior clinicians and managers, and an open process of sharing and reviewing prescribing decisions.

Clinical Competence↗
PubMed1991

Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner.

We have constructed a three-dimensional (3-D) ultrasound scanner to make examinations easier and more accurate. The accuracy of the 3-D scanner has been determined by scanning a three-dimensional model. Lengths, angles, and volume of the model were computed and compared to values determined from physical measurement. Distances between image planes were computed with a mean error of 0.4% of true value. Volume was computed with a mean error of 1.6%, or 0.64 mL +/- 0.72 mL (1 SD). We conclude that the 3-D scanner has a system error of less than 0.4%, that it does not introduce significant new errors, and that the principal source of measurement error is poor lateral resolution due to ultrasound beam width. We believe that the 3-D scanner may be a clinically useful instrument for quantitative echographic measurements.

Algorithms↗
PubMed1984

Homogeneity in Turkish Fertility Survey: implications for cluster size derived from homogeneity in basic survey variables.

"This study examines several error statistics derived from the computed variance in basic survey variables of the Turkish Fertility Survey (1978). These are standard error, design factor, design effect and rate of homogeneity. [The] results are presented for the total sample as well as for subclasses. [It is demonstrated that] previous knowledge about the homogeneity and cluster size of main survey variables [will help] to design better surveys in the future. This process can be further extended for other survey variables by imputation." (summary in TUR)

Asia↗

Refine your search to explore more results.