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PubMed1990

Day to day reproducibility of electrically inducible ventricular arrhythmias in survivors of acute myocardial infarction.

Day to day reproducibility of the response to programmed ventricular stimulation has not been evaluated in survivors of acute myocardial infarction. Programmed ventricular stimulation was performed prospectively on 2 consecutive days in 56 patients on an average of 12 +/- 5 days (range 7 to 29) after an acute myocardial infarction. No patient had a history of documented or suspected sustained ventricular tachycardia or fibrillation occurring greater than 48 h after infarction. During initial programmed ventricular stimulation, 21 patients had induction of sustained ventricular tachycardia or fibrillation (Group I), and 35 patients had induction of either nonsustained ventricular tachycardia or no ventricular tachycardia (Group II). Repeat programmed ventricular stimulation in Group I patients induced sustained ventricular tachycardia or fibrillation in 16 of 21 patients (reproducibility 76%); the maximal induced response in the other 5 patients was nonsustained ventricular tachycardia in 2 patients and fewer than six repetitive ventricular responses in 3 patients. The day to day reproducibility was significantly higher for inducible sustained ventricular tachycardia of cycle length greater than or equal to 240 ms compared with rapid sustained ventricular tachycardia of cycle length less than 240 ms (100% versus 44%, p less than 0.009) or ventricular fibrillation (100% versus 43%, p less than 0.009). Repeat programmed ventricular stimulation in Group II patients did not induce sustained ventricular arrhythmias in 31 of 35 patients (reproducibility 89%). Thus, in survivors of acute myocardial infarction, inducible slow sustained ventricular tachycardia was a highly reproducible finding, whereas inducibility of rapid sustained ventricular tachycardia and ventricular fibrillation showed a significant day to day variability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Immediate reproducibility of electrically induced sustained monomorphic ventricular tachycardia before and during antiarrhythmic therapy.

The immediate reproducibility of sustained ventricular tachycardia induction was evaluated prospectively during 106 studies performed in 53 patients with clinical sustained monomorphic ventricular tachycardia. Programmed electrical stimulation was performed twice, using the same protocol during 53 drug-free studies and 53 subsequent studies on antiarrhythmic therapy. Sustained monomorphic ventricular tachycardia was reproduced in 104 (98%) of the 106 studies. There was no significant difference in the incidence of reproducible tachycardia in the drug-free state compared with that observed during treatment with different classes of antiarrhythmic drugs. An increase in the number of extrastimuli was required to reinitiate the tachycardia in 9 (11%) of 83 studies in which single or double extrastimuli were initially required to induce the tachycardia. In 39 (37%) of 104 studies with reproducible tachycardia induction, the two tachycardias significantly differed in electrocardiographic (ECG) configuration and cycle length. These observations suggest that the overall reproducibility of ventricular tachycardia induction is sufficiently high to provide a reliable marker for evaluating the efficacy of therapeutic interventions. However, specific tachycardia characteristics such as cycle length and ECG configuration are more variable even within the same study and may be less useful in assessing the effects of subsequent interventions.

Anti-Arrhythmia Agents↗

PubMed1990

Characteristics of individuals and long term reproducibility of dietary reports: the Tecumseh Diet Methodology Study.

Food frequency reports in 1967-1969 were compared to frequency reports of the same foods asked retrospectively in 1982-1983 and 1967-1969 for 1184 respondents aged 45-64 years in the Tecumseh Community Health Study. The kappa statistic for concordance of the retrospective and baseline reports was used as a summary measure of the individual's ability to reproduce his or her earlier diet report. Reproducibility was estimated for total diet, represented by 83 foods, and for 9 subsets of foods of epidemiologic interest. In bivariate and multivariate analyses, reproducibility was strongly related to stability of diet; those whose diets changed least over the 15-year period had greatest diet reproducibility. Greater total diet reproducibility was also found among men with higher education, among women of less than 110% desirable weight reporting no special diet and among women reporting no medications. Consistent with current models of memory, the retrospective report of diet was strongly related to the current report of diet. Agreement between the retrospective and baseline diet reports was greater than agreement between the current and baseline diet reports. This indicates that, as a proxy for past diet, the retrospective report of diet is superior to the current report. Similar relationships were found for the 9 subset of foods.

Body Weight↗

PubMed1992

Reproducibility in monitoring nocturnal penile tumescence and rigidity.

The evaluation of sexual dysfunction has improved with the advent of methods to test nocturnal penile tumescence that also monitor penile rigidity. Earlier techniques may not have recorded abnormal rigidity despite normal tumescence. To test the reproducibility of penile tumescence and rigidity, the results of initial and repeat tracings performed a mean of 39 days apart were compared in 17 patients (median age 62 years). Three nocturnal patterns were identified. 1) Among the 17 patients the initial penile tumescence and rigidity pattern was reproduced on repeat testing in 15. 2) Patterns that were not reproduced in the other 2 patients were explained by the ingestion of alcohol or because of a febrile illness during the period monitored. 3) Nocturnal penile rigidity and tumescence tracings from these patients reproduced previous patterns. Monitoring of nocturnal penile tumescence and rigidity is a useful and reproducible tool in the evaluation of male sexual dysfunction.

Adult↗

PubMed1990

Five-year reproducibility of natural head posture: a longitudinal study.

Natural head posture (NHP) is being increasingly used as the logical reference position for the evaluation of craniofacial morphology. The basic premise underlying its use is that the long-term clinical reproducibility (variability) of NHP is significantly less than the variability of conventional intracranial reference planes with respect to the vertical. This study reports the results of a 5-year longitudinal study evaluating the reproducibility over time of NHP lateral cephalometric radiographs. The subjects were 126 randomly selected Chinese children in Hong Kong who were first assessed at the age of 12 years. Thirty subjects were recorded after 5 years. NHP reproducibility deteriorated over time but showed signs of stabilizing after 1 to 1 1/2 years. The method error was 1.93 degrees after 1 to 2 hours, 2.34 degrees after 3 to 6 months, and 3.04 degrees after 5 years. The individual variability of NHP reproducibility also increased over time. The standard deviation of the SN/vertical angulation was 2.61 degrees after 1 to 2 hours, 3.16 degrees after 3 to 6 months, and 4.20 degrees after 5 years. Further longitudinal data are required to determine whether NHP reproducibility continues to deteriorate after 5 years. After 5 years, however, the variance of NHP (9.24 degrees [= 3.04(2)]) remains significantly less than the variance of intracranial reference planes to the vertical (25 degrees to 36 degrees).

Cephalometry↗

PubMedDate not supplied

Sonicated echocardiographic contrast agents: reproducibility studies.

This article describes the production, analysis, and reproducibility of forming microbubbles for contrast ultrasound imaging. The sonication method used to generate microbubbles was tested by four independent observers, and a subsequent laser particle counter analysis of microbubble size and concentration determined the reproducibility of the method. The results indicated that the mean bubble size was 3.3 +/- 1.2 microns for the entire group, based on three trials of each of the four participants. The characteristics of the bubble size of the microbubbles between observers were assessed with a Poisson distribution with the reproducibility based on the sample mean for each observer's trials. Standardization and calibration of the laser particle counter was accomplished with commercially available latex spheres, sonicated albumin microspheres, and a Coulter counter analysis. Our results indicate that the sonication technique generates small microbubbles with a reproducible uniform size distribution. The method of microbubble production is reproducible and can be widely applied for use in contrast echocardiographic perfusion imaging of tissue in a variety of research and clinical studies.

Air↗

PubMed1990

Reproducibility and action levels for gamma camera uniformity.

Deciding on the action level for gamma camera non-uniformity is difficult because the reproducibilities of quality control measurements and service adjustments are usually unknown. This work evaluated the reproducibilities of integral uniformity (IU), differential uniformity (DU) and the corrected relative standard deviation (CRSD). The latter was calculated by removing from the relative standard deviation of the pixel counts the component due to statistical fluctuations. The reproducibility of each parameter was evaluated by analysing 10 intrinsic flood acquisitions with total counts of 2, 5, 10 and 30 million. All three parameters were less reproducible at the lower count densities, but as expected IU and DU also showed higher mean values. CRSD was consistent and highly reproducible, at all count densities. At 10 million counts CRSD had a coefficient of variation (COV) of 1.3% which was a five-fold improvement over the 6.6% and 6.1% found for IU and DU, respectively. The relative sensitivity of IU, DU and CRSD was compared in monthly measurements on 10 gamma cameras over one year. No significant difference in relative sensitivity was demonstrated: a change in camera performance produced about the same percentage change in each parameter. The precision with which service engineers adjust gamma cameras was also assessed by measuring the uniformity of 10 gamma cameras immediately after service adjustment at monthly intervals over one year. Finally, general action levels were defined for IU, DU and CRSD at 7%, 5% and 2.5% respectively.

Gamma Cameras↗

PubMed1991

Reproducibility of tolerance tests that are useful in the identification of campylobacteria.

Twenty type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, were used to assess the reproducibility of 25 phenotypic tests that are used in the identification of such organisms. Twenty-two of the tests depended on growth inhibition, and each of these tolerance tests was performed by using three different basal media. Although the overall reproducibility of the tests with each basal medium exceeded 89%, the proportion of strains that were able to grow in a reproducible manner on the basal media varied from 100% for blood agar and 50% for nutrient agar to 5% for brucella agar. In general, test reproducibility was highest with the basal medium that supported the most luxuriant growth. For the majority of tests, the basal medium which gave the optimum reproducibility could be determined.

Animals↗

PubMed1990

Observer reproducibility in grading dysplasia in colorectal adenomas: comparison between two different grading systems.

The two most well known and well defined grading systems for dysplasia in colorectal adenomas were compared with regard to reproducibility. The Konishi-Morson system (KMS) operates with several histological and cytological variables and grades of mild, moderate, and severe dysplasia. The Kozuka system is based on the extent of nuclear pseudostratification and also has three grades of dysplasia (III-V). As the group of severe dysplasia is very large in this system, it was extended with two higher grades, similarly based on individual histological criteria, known hereafter as the extended Kozuka system (EKS). Fifty six adenomas were graded by two observers, each observer grading twice according to the KMS criteria and twice according to EKS criteria. Intraobserver reproducibility was excellent for the KMS and moderate for the EKS, but this was not significant. The overall interobserver reproducibility was similar (moderate) for the KMS and for the EKS. Kappa values for interobserver reproducibility on individual categories were excellent for severe dysplasia according to the KMS, but low for all other categories in both systems. By simplifying both systems into two groups a high reproducibility can be obtained, but this implies that all the original grades (III-V) for the EKS must be grouped together. It is therefore recommended that a simplified KMS is used for further studies on the biological importance of dysplasia and for comparison between histological changes and other markers for colorectal neoplasia.

Adenoma↗

PubMed1992

Reproducibility of measurements of coronary narrowings by videodensitometry and by digital calipers.

Computer-assisted videodensitometry has been shown to be a reliable and reproducible method of measuring absolute and relative coronary narrowings. Using a commercially available analyzer (Vanguard XR70) we confirmed intra- and interobserver reproducibilities in 34 narrowings in 9 patients. Analyses were performed on normal area and diameter, stenotic area and diameter, percent area stenosis and percent diameter stenosis. For all 6 analyses, excellent intra- and interobserver correlations were found (r = 0.93-0.98), with slopes close to 1 and intercepts close to zero. Caliper measurements (Mitutoyo Digimatic) of the same lesions by the same observers showed good inter- and intraobserver reproducibility for percent diameter stenosis (r = 0.90 and 0.86), with mean interobserver difference of 1.67 +/- (SD) 6.4% and intraobserver difference of 2.97 +/- (SD) 7.9%. However, less good correlations were found between caliper and videodensitometric measurements of percent diameter stenosis; r = 0.61 and 0.76 for the two observers. These data suggest that videodensitometry is a highly reproducible quantitative angiographic method, suitable for documenting changes in the severity of coronary artery lesions, both spontaneous or related to interventions. Caliper measurements do not provide the same degree of accuracy, but they have acceptable reproducibility in measuring diameter stenosis. As such, they are also suitable for assessing changes in severity of coronary artery lesions in individual patients.

Angioplasty, Balloon, Coronary↗

PubMed1990

Reproducibility studies with the Zeiss SLC system and animal cataract models.

Scheimpflug photography has become the basic method for documentation of lens transparency changes in clinical and experimental ophthalmology, due to its high reproducibility. In animal cataract studies, the reproducibility is strongly influenced by the handling characteristics of the camera used, due to limited cooperation of the animal. The reproducibility of the Zeiss SLC system, which offers a direct quality control of the image on the video screen, was tested with 2 animal cataract models, the ultraviolet B (UVB)-induced cataract and the true diabetic cataract in the Brown-Norway rat. 10 rats each of the 2 cataract models and of an untreated control group were photographed in a random order on 3 occasions on the same day by the same photographer. Quality control and densitometry were performed by the same system operator, the measurement window was positioned standardly, coincident with the optical axis of the eye. Statistical comparison was carried out in the capsular layer, that is the area of initial cataract development in both models, and in the cortical layer, into which the diabetic cataract progresses during its later stages of development. The nuclear layer was also evaluated, but has no direct relation to one of the models employed. The results clearly indicate that the reproducibility is predominantly influenced by the homogeneity or inhomogeneity of the cataract model employed. The system operator and the photographer provided that they are well trained, have minor influence on the reproducibility of the Zeiss SLC system.

Animals↗

PubMed1989

A protocol for performing reproducible methacholine inhalation tests in children with moderate to severe asthma.

Reproducibility of methacholine inhalation tests (MIT) over a 2-wk period has been established in adult populations, but similar studies demonstrating reproducibility in children are lacking. We set out to establish the reproducibility of MIT in children as a prerequisite for a study of the natural history of airway hyperreactivity in asthmatic children. Most inhalation testing is done in persons with mild asthma because the recommended time interval for the withholding of medications prior to bronchial challenge is poorly tolerated by more labile asthmatics. In order to evaluate asthmatics with more severe disease, we modified a standardized method of methacholine inhalation to include a three-tier pretest medication regimen and investigated the reproducibility of this MIT protocol in 11 children as young as 6 yr of age. The three tiers were designed to keep baseline FEV1 greater than or equal to 70% predicted since diminished baseline airway caliber may affect MIT results. Eight of the 11 children were bronchodilator-dependent, and two of the eight also required inhaled steroids. Eleven children (6 to 13 yr of age) underwent MIT, between December and March, 1 day, 1 wk, and 1 month after an initial test. The PD20FEV1 using cumulative breath units (BU) were compared. The range of PD20FEV1 in the 11 children was 0.27 to 14.4 BU, with nine subjects classified as severe (PD20FEV1 less than 2.5 BU). We found a high degree of reproducibility of MIT. The interest correlation coefficient (r) was 0.98 after 1 day, 0.95 after 1 wk, and 0.96 after 1 month.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Long-term reproducibility of respiratory gas exchange measurements during exercise in patients with stable cardiac failure.

Present-day technology has greatly facilitated the monitoring of respiratory gas exchange in the clinical exercise laboratory. Despite the growing use of these techniques to assess the severity and progression of disease or therapeutic response in patients with heart failure, the long-term reproducibility of oxygen uptake (VO2), carbon dioxide production, minute ventilation, heart rate (HR), and blood pressure at rest and during incremental exercise in such patients, to our knowledge, has not been evaluated. Therefore, the purpose of this study was to quantify the reproducibility of these variables along with exercise duration, maximum VO2 (VO2max) and anaerobic threshold in a group of 16 patients (61 +/- 7 years, 14 male) with chronic, stable cardiac failure of varying severity and etiology who had five or more incremental treadmill exercise tests over a period of time that ranged from 3 to 22 months. For each variable, reproducibility was represented by the coefficient of variation (CVAR). Except for exercise duration, CVAR was not a function of the severity of heart failure and, for all variables, patient-to-patient variation in CVAR was approximately 9 percent. The maximum CVAR for HR, systolic blood pressure, VO2, and VO2max was generally below 10.5 percent and for exercise duration and anaerobic threshold it was less than 12.5 percent. Based on this retrospective analysis, it is concluded that reproducible respiratory gas exchange and HR exercise responses are obtainable over extended periods of time in patients with stable, chronic cardiac failure. Exercise duration, however, is less reproducible in patients with moderate to severe failure.

Aged↗

PubMed1990

Reproducibility of ambulatory gastric pH recordings in the corpus and antrum. Effect of food, time, and electrode position.

The reproducibility of simultaneous, long-term, ambulatory gastric pH recordings in the antrum and corpus was investigated in nine healthy subjects who underwent three separate, 27-h gastric double pH-metries. Intraindividual reproducibility for the entire 27-h recording period was good in the corpus (Kendall's concordance coefficient, W' = 0.6393, p less than 0.025) but not in the antrum (W' = 0.4806, NS). Analysis of predefined time periods showed that non-meal daytime pH was reproducible in the corpus (W' = 0.6531, p less than 0.025) but not in the antrum (W' = 0.3395, NS), whereas mealtime pH was reproducible in the antrum (W' = 0.7159, p less than 0.005) but not in the corpus (W' = 0.4954, NS); nocturnal pH was not reproducible in either the antrum or the corpus. These results reflect the functional separation of corpus and antrum and their differing responses to food. Thus, studies of gastric acidity over long periods should be conducted in the corpus, whereas studies of gastric acidity over shorter, meal-related periods should be conducted with a second electrode in the antrum.

Adult↗

PubMed1992

A comparison of six different ways of expressing the bronchodilating response in asthma and COPD; reproducibility and dependence of prebronchodilator FEV1.

Various indices are used to express the bronchodilating response. It is unclear, however, which index is most informative. The aim of this study was to compare six expressions of the bronchodilating response and to examine: 1) the independence of the prebronchodilator forced expiratory volume in one second (FEV1); and 2) the reproducibility of the bronchodilating response. Bronchodilating responses (increases in FEV1 60 min after salbutamol 400 micrograms and ipratropium bromide 80 micrograms) on six test occasions, during two years, of 183 patients (72 asthma, 111 chronic obstructive pulmonary disease (COPD)) from a large bronchodilator intervention study were used. The dependence of the prebronchodilator FEV1 was investigated both between patients (cross-sectional analysis) and within patients (longitudinal analysis) by means of linear regression analysis. The reproducibility of the bronchodilating response was calculated by means of the coefficients of variation (CVs) of the six bronchodilating responses during two years. The CVs of the six expression indices were compared by analysis of variance (ANOVA). No index was independent of the prebronchodilator FEV1. However, some indices were significantly more dependent on the prebronchodilator lung function and, therefore, less reproducible than others. The "% initial" index (change as a percentage of the prebronchodilator value) was the most dependent on the prebronchodilator lung function and had the worst reproducibility (CV ranged from 50-61%). The "% possible" (change as a percentage of the predicted minus prebronchodilator value) and "% achievable" (change as a percentage of the maximal postbronchodilator minus prebronchodilator value) indices were the least dependent on the prebronchodilator value and had the highest reproducibility (CV ranging from 34-53%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

A reproducible method for producing and quantifying the stages of fracture repair.

Male CD-1 mice, 4 to 6 months of age, were used to establish a reproducible model to study the stages of fracture repair. A custom-designed fracture apparatus was constructed, and trials with it demonstrated its capacity to reliably reproduce a closed fracture of the tibia. Dietary and sleep habits in the treated mice were the same as unfractured control mice. Four stages of fracture repair were documented and the duration of each stage was quantifiable and reproducible. The last stage of fracture repair was completed by 21 days postfracture. The reproducibility of the fracture, the reproducibility of the times and stages of fracture repair, the relatively short time to complete the fracture repair process, and the minimal discomfort which allowed the mice to maintain a normal daily routine, suggest that this is an ideal animal model for studying the fracture repair process.

Animals↗

PubMed1989

Reproducibility of iodine-123-hippuran renoscintigraphy in the normal pig at various flow rates.

Twenty-two pigs with normal kidney function and upper urinary tracts were examined with renoscintigraphies once a week for 4 weeks. In order to study the influence of urine flow on the reproducibility, renoscintigraphies were undertaken during various urinary flow rates. Renal split function was reproducible at any level of and independent of the urinary flow rates. For parenchymal and pelvic mean transit times a normogram was constructed for selected urinary flow intervals. An inverse relationship to urine production was seen. Parenchymal and pelvic transit times were fully reproducible when data were compared in two or three consecutive examinations of the same kidney at the same urinary flow rate. Both parenchymal and pelvic mean transit times were however significantly different (p less than 0.001) in kidneys studied from one urinary flow rate to another. Single kidney hippuran clearance was fully reproducible when compared in the same urinary flow interval. However a significant difference was found (p less than 0.05) when single kidney hippuran clearance was compared in renographies undertaken at different urinary flow intervals. Furthermore the study suggests that the size of hippuran clearance is dependent on the urine production, since an increase in hippuran clearance was seen in relation to increase in urinary flow. In conclusion this pig study showed, that monitoring of the urinary flow rate is extremely important in this very commonly used clinical investigation, and that the investigation should be performed in the same state of hydration at any renography to obtain reproducible results.

Animals↗

PubMed1989

[Reproducibility of the Doppler spectrum of the left ventricular stroke volume].

The left ventricular stroke volume was determined in 15 healthy male volunteers of the same age (21-23 yrs). The systolic function was characterized by six, the diastolic function by five parameters. The diameter and the cross-sectional areas of the outflow tract were determined. Intraobserver, interobserver and day-to-day variability of these parameters were investigated. The reproducibility was tested by 4 statistical methods. The significance of the differences between the mean values was determined, as well as the percentual difference of the mean values and of the variation coefficients. Linear regression analysis was done and the correlation coefficient was determined for each parameter. The variation coefficient could be regarded as the best statistical method for characterizing the reproducibility. Thus the simplest, directly measured Doppler parameters gave the best reproducibility. The reproducibility of the complex, calculated parameters was poorer. Comparing the intra- and interobserver reproducibility error, the former one was less.

Adult↗