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At least 973 records · Page 54Linked to original sources

PubMed2006

Nasal NO measurement by direct sampling from the nose during breathhold: Aspiration flow, nasal resistance and reproducibility.

The objective of this study was assessment of the effect of aspiration flow, the nasal cycle, and time on nasal nitric oxide (nNO) concentrations in air sampled from one nostril during breathhold. nNO was measured in 45 healthy subjects (19 males, aged 18-45 years) from one nostril during breathholding. We compared nNO values and time to plateau in both nostrils with 3 aspiration flows (280, 700, 1,200 ml/min) and assessed the short-term and long-term reproducibility. Mean nNO values at flows of 280, 700 and 1,200 ml/min differed significantly (P < 0.01): 854, 474, 380 ppb, respectively. The (median) plateau was reached after 6, 4 and 3 s for the different flows. The within-subject coefficient of variability was always < 5%. We found no difference in nNO between left-, right-, largest or smallest nostril (P > 0.10). nNO values after 6, 24 h and 7 days were not significantly different from baseline (P > 0.10) and showed fair reproducibility. The highest aspiration flow was experienced as unpleasant. nNO can be measured in either nostril and shows no diurnal variation. The measurement is quick, reproducible, feasible and best accepted with an aspiration flow of 700 ml/min during breathhold for 10 s.

Adolescent↗

PubMed2002

Reproducibility of the blood lactate threshold, 4 mmol.l(-1) marker, heart rate and ratings of perceived exertion during incremental treadmill exercise in humans.

The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related to fitness levels were also investigated. A group of 20 men [mean (SD)] [age 20.5 (1.4) years] and 16 women [age 21.2 (0.9) years] took part in the study. The subjects performed two identical incremental exercise tests consisting of at least six 4 min stages. Blood lactate concentrations, HR and RPE were recorded at the end of each stage. Limits of agreement (LoA), correlation coefficients and 95% confidence intervals for the mean difference between tests were employed to investigate the level of agreement and reproducibility of blood lactate concentration, HR and RPE. For the group as a whole, the sample correlation coefficient for speed at v(Th,la)- was r=0.88, and was r=0.92 for the speed at v(la)-(,4). At v(Th,la) -, the correlation coefficients for the moderately fit and unfit were r=0.94 and r=0.36, respectively, and at v(la)-(,4) r=0.93 and r=0.68, respectively. The LoA for the moderately fit group indicated that a change of 1.62 km.h(-1) in v(Th,la)- would be necessary to be considered a change in training status. For HR and RPE, relationships between the tests were generally poor. The LoA suggested that changes in scores must be unacceptably large. These findings cast doubt on the sensitivity of testing for change of blood lactate concentration, HR and RPE in this population.

Adult↗

PubMed2003

Reproducibility of the exponential rise technique of CO(2) rebreathing for measuring P(v)CO(2) and C(v)CO(2 )to non-invasively estimate cardiac output during incremental, maximal treadmill exercise.

The purpose of this study was to determine the reproducibility of the indirect Fick method for the measurement of mixed venous carbon dioxide partial pressure (P(v)CO(2)) and venous carbon dioxide content (C(v)CO(2)) for estimation of cardiac output (Q(c)), using the exponential rise method of carbon dioxide rebreathing, during non-steady-state treadmill exercise. Ten healthy participants (eight female and two male) performed three incremental, maximal exercise treadmill tests to exhaustion within 1 week. Non-invasive Q(c) measurements were evaluated at rest, during each 3-min stage, and at peak exercise, across three identical treadmill tests, using the exponential rise technique for measuring mixed venous PCO(2) and CCO(2) and estimating venous-arterio carbon dioxide content difference (C(v-a)CO(2)). Measurements were divided into measured or estimated variables [heart rate (HR), oxygen consumption (VO(2)), volume of expired carbon dioxide (VCO(2)), end-tidal carbon dioxide (P(ET)CO(2)), arterial carbon dioxide partial pressure (P(a)CO(2)), venous carbon dioxide partial pressure ( P(v)CO(2)), and C(v-a)CO(2)] and cardiorespiratory variables derived from the measured variables [Q(c), stroke volume (V(s)), and arteriovenous oxygen difference ( C(a-v)O(2))]. In general, the derived cardiorespiratory variables demonstrated acceptable (R=0.61) to high (R>0.80) reproducibility, especially at higher intensities and peak exercise. Measured variables, excluding P(a)CO(2) and C(v-a)CO(2), also demonstrated acceptable (R=0.6 to 0.79) to high reliability. The current study demonstrated acceptable to high reproducibility of the exponential rise indirect Fick method in measurement of mixed venous PCO(2) and CCO(2) for estimation of Q(c) during incremental treadmill exercise testing, especially at high-intensity and peak exercise.

Adult↗

PubMed2001

Reproducibility of the parameters of the on-transient cardiopulmonary responses during moderate exercise in patients with chronic obstructive pulmonary disease.

To be clinically useful as indices reflective of altered physiological function consequent to interventions in patients with chronic obstructive pulmonary disease (COPD), the time constant (tau) and steady-state amplitude of the kinetic responses for oxygen uptake (VO2) carbon dioxide output (VCO2) ventilation (VE) and heart rate (HR) have to be appropriately differentiable and reproducible. We therefore assessed the reproducibility of tau and steady state amplitude values in 41 patients with severe COPD [mean (SD)] [forced expiratory volume in 1 s = 41 (7)% predicted], aged 64 (5) years. Of the total, 6 of the patients (15%) did not produce breath-by-breath data of sufficient quality to warrant kinetic analysis. The remaining 35 patients completed two moderate-intensity 10 min square-wave exercise tests separated by 2 h, both before and after an endurance training programme. Tests were conducted on an electromagnetically-braked cycle ergometer at an exercise intensity corresponding to 80% of the estimated lactate threshold (thetaLa) or 50% of peak oxygen uptake if thetaLa was insufficiently differentiable. Breath-by-breath measurements of VO2, VCO2, VE and HR were averaged into 10 s bins and the on-transient response kinetics were estimated using a mono-exponential model. Analysing the pre-training and the post-training test 1 and test 2 comparisons together, the test 1- test 2 differences were not significantly different from 0 for either tau or A. The standard deviation of the test 1- test 2 differences allowed us to define the magnitude of change that would reach statistical significance. For tau, this averaged some 8, 10, 11 and 8 s, for VO2, VCO2, VE and HR, respectively, for a one-tailed paired-comparisons test (i.e. appropriate for assessing hypothesised improvements resulting from an intervention); for a two-tailed comparison, the differences were approximately 2 s greater. The corresponding one-tailed values for A were 100 ml x min(-1), 95 ml x min(-1), 2.5 1 x min(-1) and 4 beats x min(-1), respectively; the two-tailed values were 10%-15% greater. We therefore conclude that both tau and A for moderate-intensity exercise can be reproducibly estimated in patients with COPD when the data set provides a sufficiently large amplitude of response and sufficiently low sample variability to allow appropriate parameter estimation.

Aged↗

PubMed2000

Geometry and reproducibility in 360 degrees fundoplication.

BACKGROUND: In this study, we set out to precisely define two symmetrical points-a on the anterior fundic wall and b on the posterior fundic wall. These points, when advanced around a 60-Fr bougie-filled esophagus, will meet on the right side, to the right of the anterior vagus nerve, to create a reliable, reproducible, loose (i.e., or "floppy") 360 degrees fundoplication (FP). METHODS: For the terms of this study, circumference = c; diameter = d; c/d = pi; pi = 3.14; and d(cm) = Fr/30. Using a flexible plastic ruler, we measured, in cadavers (n = 5) and intraoperatively (n = 16), esophageal c at the gastroesophageal junction (GEJ) with a 60-Fr bougie in place; d was calculated from c. RESULTS: The smallest measured value for c was 7.5 cm (d = 2.39 cm); the largest value for c was 10.0 cm (d = 3.18 cm). The mean value was 8.35 cm (d = 2.66 cm). Points a and b are established by measuring laterally from a point where the greater curve meets the GEJ in the bougie-filled esophagus. Point a is 6.0 cm laterally and 6.0 cm below the short gastric vessels on the anterior fundus; point b is 6.0 cm laterally in a symmetrical position on the posterior fundus. Connecting these three points as a line defines the inner c of the completed FP and measures 12.0 cm. This gives an internal d of 3.82 cm for the FP. This is >1 cm larger than d for the mean measured external esophageal c of 8.35 cm where d = 2.66 cm. This technique creates a correctly oriented, symmetrical, "floppy," true fundoplication. It avoids wrapping or twisting the fundus around the GEJ. The technique is easily taught and reproducible. CONCLUSIONS: Two points, measured a horizontal distance of 6.0 cm from the GEJ, symmetrically placed on the anterior (point a) and posterior (point b) fundus can be brought anterior (a) and posterior (b) to the esophagus and sutured to the right of the anterior vagus nerve to reliably and reproducibly create a "floppy" 360 degrees fundoplication.

Esophagus↗

PubMedDate not supplied

Amniotic infection syndrome: nosology and reproducibility of placental reaction patterns.

Clinically responsive placental examination seeks to provide useful information regarding the etiology, prognosis, and recurrence risk of pregnancy disorders. The purpose of this study was to assemble and validate a complete set of the placental reaction patterns seen with amniotic fluid infection in the hope that this might provide a standardized diagnostic framework useful for practicing pathologists. Study cases (14 with amniotic fluid infection, 6 controls) were reviewed blindly by six pathologists after agreement on a standard set of diagnostic criteria. After analysis of initial results, criteria were refined and a second, overlapping set of cases were reviewed. Majority vote served as the gold standard. Grading and staging of maternal and fetal inflammatory responses was found to be more reproducible using a two- versus three-tiered grading system than a three- versus five-tiered staging system (overall agreement 81% vs. 71%). Sensitivity, specificity, and efficiency for individual observations ranged from 67-100% (24/30 > 90%). Reproducibility was measured by unweighted kappa values and interpreted as follows: < 0.2, poor; 0.2-0.6, fair/moderate; > 0.6, substantial. Kappa values for the 12 lesions evaluated in 20 cases by the six pathologists were: acute chorioamnionitis/maternal inflammatory response (any, 0.93; severe 0.76; advanced stage, 0.49); chronic (subacute) chorioamnionitis (0.25); acute chorioamnionitis/fetal inflammatory response (any, 0.90; severe, 0.55; advanced stage, 0.52); chorionic vessel thrombi (0.37); peripheral funisitis (0.84); acute villitis (0.90); acute intervillositis/intervillous abscesses (0.65), and decidual plasma cells (0.30). Adoption of this clearly defined, clinically relevant, and pathologically reproducible terminology could enhance clinicopathologic correlation and provide a framework for future clinical research.

Adult↗

PubMed2004

Maternal vascular underperfusion: nosology and reproducibility of placental reaction patterns.

Placental examination can be a useful tool for specifying the etiology, prognosis, and recurrence risk of pregnancy disorders. The purpose of this study was to test the reliability of a predetermined set of placental reaction patterns seen with maternal vascular underperfusion in the hope that this might provide a useful diagnostic framework for practicing pathologists. Study cases (14 with clinical and pathologic evidence of maternal underperfusion plus 6 controls) were evaluated for the presence or absence of 11 lesions by eight perinatal pathologists. After analysis of initial results, diagnostic criteria were refined and a second, overlapping set of cases was reviewed. The collective sensitivity, specificity, and efficiency of individual assessments for the 11 lesions relative to the group consensus ranged from 74-93% (22/33 > 90%). Reproducibility was measured by unweighted kappa-values and interpreted as follows: < 0.2 poor, 0.2-0.6 fair/moderate, > 0.6 substantial. Kappa values for lesions affecting villi and the intervillous space were increased syncytial knots (any -0.42, severe -0.50), villous agglutination (0.42), increased intervillous fibrin (0.25), and distal villous hypoplasia (0.57). Individual estimates of percent involvement for syncytial knots, intervillous fibrin, and distal villous hypoplasia were correlated with placental and fetal weight for gestational age. Extent of increased intervillous fibrin showed the strongest correlation with both placental weight ( R = -0.64) and fetal weight ( R = -0.45). Kappa values for lesions affecting maternal vessels and the implantation site were acute atherosis (0.50), mural hypertrophy of membrane arterioles (0.43), muscularized basal plate arteries (0.48), increased placental site giant cells (0.54), and immature intermediate trophoblast (0.36). Correlation of maternal vessel and implantation site lesions with the clinical diagnosis of preeclampsia showed that excessive placental site giant cells and immature intermediate trophoblast were more sensitive and efficient predictors, whereas atherosis and muscularized basal plate arteries were more specific. Kappa value for a thin umbilical cord, a possible indicator of fetal volume depletion, was 0.61. Reproducibility for a global impression of maternal vascular underperfusion, taking into account all of the above lesions, was moderate (kappa 0.54) and improved after inclusion of additional pathologic and clinical data (kappa 0.68). Adoption of this clearly defined, clinically relevant, and pathologically reproducible terminology could enhance clinicopathologic correlation and provide a more objective framework for future clinical research.

Adult↗

PubMed2006

Reproducibility of intravascular ultrasound radiofrequency data analysis: implications for the design of longitudinal studies.

OBJECTIVES: The purpose of this study was to assess in vivo the reproducibility of tissue characterization using spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (IVUS-VH). BACKGROUND: Despite the need for reproducibility data to design longitudinal studies, such information remains unexplored. METHODS AND RESULTS: IVUS-VH (Volcano Corp., Rancho Cordova, USA) was performed in patients referred for elective percutaneous intervention and in whom a non-intervened vessel was judged suitable for a safe IVUS interrogation. The IVUS catheters used were commercially available catheters (20 MHz, Volcano Corp., Rancho Cordova, USA). Following IVUS-VH acquisition, and after the disengagement and re-engagement of the guiding catheter, an additional acquisition was performed using a new IVUS catheter. Fifteen patients with 16 non-significant lesions were assessed by 2 independent observers. The relative inter-catheter differences regarding geometrical measurements were negligible for both observers. The inter-catheter relative difference in plaque cross-sectional area (CSA) was 3.2% for observer 1 and 0.5% for observer 2. The limits of agreement for (observer 1 measurements) lumen, vessel, plaque and plaque burden measurements were 0.82, -1.10 mm(2); 0.80, -0.66 mm(2); 1.08, -0.66 mm(2); and 5.83, -3.89%; respectively. Limits of agreement for calcium, fibrous, fibrolipidic and necrotic core CSA measurements were 0.22, -0.25 mm(2); 1.02, -0.71 mm(2); 0.61, -0.65 mm(2); and 0.43, -0.38 mm(2) respectively. Regarding the inter-observer agreement, the limits of agreement for lumen, vessel, plaque and plaque burden measurements were 2.61, -2.09 mm(2); 2.20-3.03 mm(2); 1.70, -3.04 mm(2); and 9.16, -16.41%; respectively, and for calcium, fibrous, fibrolipidic and necrotic core measurements of 0.08, -0.09 mm(2); 0.89, -1.28 mm(2); 0.74, -1.06 mm(2); and 0.16, -0.20 mm(2); respectively. CONCLUSIONS: The present study demonstrates that the geometrical and compositional output of IVUS-VH is acceptably reproducible.

Coronary Disease↗

PubMed1993

Reproducibility and validity of food intake measurements from a semiquantitative food frequency questionnaire.

Few food frequency questionnaires have been evaluated for their ability to assess intakes of individual foods that may be related to disease independently of their nutrient content. The reproducibility and validity of food intake measurements by a 131-item semiquantitative food frequency questionnaire were evaluated in a sample of 127 men from the Health Professionals Follow-up Study, a large longitudinal study of diet and disease. Each subject completed two questionnaires 1 year apart and two 1-week diet records 6 months apart during the intervening year. Pearson correlations assessing reproducibility between food intakes from the two questionnaires ranged from .31 for pie to .92 for coffee (mean = .59). Validity was measured by comparing food intakes from the second questionnaire with those from the diet records. Pearson correlations corrected for within-person weekly variation in diet record data ranged from .17 for other nuts to .95 for bananas (mean = .63). Large within-person variation precluded the calculation of accurate validity correlations for 29 foods. As we previously observed in women, the foods most often overreported were fruits and vegetables, and meats and dairy products were most often underreported. With few exceptions, reasonable levels of reproducibility and validity were observed for intake of individual foods in this extensive food frequency questionnaire.

Adult↗

PubMed1992

Reproducibility of a symptomatic response to upright tilt in young patients with unexplained syncope.

Serial upright tilt testing has been advocated as a possible therapeutic end point in treating patients with recurrent syncope, but the reproducibility of such testing has not been well-established in the absence of therapy. In 21 patients with recurrent syncope and a symptomatic response to upright tilt testing, tilt was repeated following a 25- to 30-minute recovery. Syncope or presyncope was reproduced in 14 of 21 patients on repeat tilt; 4 of 21 patients experienced milder symptoms, and 3 of 21 patients remained entirely asymptomatic on repeat tilt. The pattern of physiologic response was different during initial and repeat tilt in 7 of the 21 patients. Blood pressure and heart rate (before and during symptoms) were similar for the group on initial and repeat tilt. The abnormal physiologic response and associated symptoms elicited during upright tilt testing for unexplained syncope can be reproduced on immediate repeat tilt testing in most patients. However, the frequently attenuated response during repeat testing may limit its use as a therapeutic end point in individual patients.

Adolescent↗

PubMed1992

Reproducibility of quantitative backscatter echocardiographic imaging in normal subjects.

Cyclic backscatter variation is useful in differentiating normal from ischemic and myopathic myocardium; however, there are few data on the reproducibility of clinical cyclic variation measurements. Therefore, a study using 2-dimensional and M-mode backscatter imaging was performed in 20 normal male subjects by 2 observers at an initial session and by 1 of the observers after 1 week. Cyclic variation on M-mode was calculated as the difference between the end-diastolic backscatter and the backscatter at the nadir. Two-dimensional determinations of backscatter were made using a single frame at end-diastole and one at end-systole. The cyclic change was the difference between backscatter measured in the end-diastolic and end-systolic frames. There were no statistically significant differences in analysis of variance among the grouped repeated measurements in either the interventricular septum or the posterior left ventricular wall. At the initial session, cyclic backscatter variation in the posterior wall using M-mode techniques was 5.9 +/- 1.8 dB (SD). The cyclic change in backscatter in the septal wall, using the 2-dimensional technique, was 4.3 +/- 2.4 dB. In the posterior wall, the cyclic change in backscatter was 5.7 +/- 1.7 dB. Pairwise observer correlations between repeated measurements ranged from -0.48 to 0.45. Thus, although there were no significant differences in group means on repeat measurements, repeated measurements in individual subjects were not reliably reproduced because of limited independent sampling of backscatter measurements at only 2 points in the heart cycle. Increased independent sampling and measurement from a backscatter waveform throughout the cardiac cycle may improve reproducibility of measurements.

Adult↗

PubMed1992

Reproducibility of mandibular motion and muscle activity levels using a commercial computer recording system.

A commercial computer recording system (BioPak) was tested for its accuracy and reproducibility in recording mandibular motion and muscle activity levels (EMG). Accuracy of measurements of mandibular motion was tested using sliding calipers. Accuracy of muscle activity levels was checked with a sine-wave calibration signal of known amplitude and frequency. Reproducibility of motion and of EMG was made using five control subjects each tested on 3 separate days. Computer measurements of motion were found to require correction for nonlinearity at openings beyond 45 mm. Most maximum voluntary excursions were found to be more reproducible than motions during mastication. However, lateral deviation during opening was strongly affected by magnet orientation and varied greatly between trials. Electromyographic recordings were distorted by improper treatment of high-frequency components of the signal and also varied greatly between trials. This study suggests that the BioPak system may indicate changes in some measures of mandibular motion and EMG levels in patients for whom no changes have occurred.

Adult↗

PubMed1990

Capillary blood cell velocity in finger nailfold: characteristics and reproducibility of the local cold response.

The characteristics and reproducibility of nailfold capillary blood cell velocity (CBV) of the local cold response was evaluated in 30 cases by video-microscopy using a flying-spot technique. CBV, as well as flow stop duration during cooling, from a first and second test was significantly (P less than 0.05) reproducible, whether or not the test was repeated after 60 min or after an interval of 12 weeks. Because of interindividual variations in rest CBV, and a better reproducibility of the flow stop duration, this last parameter is more useful in clinical practice for follow-up evaluations of the local cold response test. The usefulness of the flying-spot generator for rapid and accurate measurement of CBV in finger nailfold capillaries is demonstrated in normal subjects and patients with primary Raynaud syndrome during a local cooling test.

Adult↗

PubMed1992

Reproducibility of data from a hand-held digital pulp tester used on teeth and oral soft tissue.

Controlled studies of the reproducibility of data from electronic pulp testing instruments are limited and contain few statistical analyses. The reproducibility of these readings is important if the instrument is to be used for determining differences in sensitivity. Twenty human subjects (16 male) were used in this study. One incisor, one premolar, one molar tooth with small or no restorations, and two gingival soft tissue positions from each upper and lower arch of each subject were stimulated with the Analytic Technology vitality scanner. This procedure was repeated twice with a 5-minute rest between each trial, for a total of three trials. Each subject was then seen again after a period of at least 3 days, at which time the trials were repeated. The collected data were grouped by trial, tooth position, and day. Paired t test analysis of both the absolute difference between any two trials on the same day and the average of the absolute differences between corresponding trials on days 1 and 2 showed no statistically significant differences (p greater than 0.05). Accommodation to the stimulus was evaluated by examining differences in the mean values between the three same-day trials. The Analytic Technology vitality scanner was found to be reproducible both for consecutive same-day trials and for corresponding trials on different days. No same-day trends in meter readings were noted.

Adult↗

PubMed1992

Syntactic structure analysis in invasive breast cancer: analysis of reproducibility, biologic background, and prognostic value.

The reproducibility, biologic background, and prognostic value of syntactic structure analysis were studied in a group of 94 patients with invasive primary breast cancer. Using an interactive digitizing video overlay system, the centers of malignant breast cancer nuclei were marked in the five (subjectively) most cellular fields of vision for each case at a final magnification of X1,200, and the corresponding minimum spanning tree was composed for each field. From each minimum spanning tree, 10 syntactic structure features were derived; subsequently, the mean, standard deviation, minimum, and maximum values of the five fields analyzed were calculated for further statistical analysis. Forty statistics thus were available for each case. The reproducibility of repeatedly measuring the same field (independent of nuclearity) and the same patient twice by the same or different observers was good for most of the syntactic structure features. When comparing the statistics of the syntactic structure features with other established prognosticators, correlations were found with (in this order) standard deviation and mean nuclear area (expressing nuclear differentiation), volume percentage epithelium (expressing architectural differentiation), and mitotic activity index. In univariate survival analysis several syntactic structure statistics yielded prognostic significance, the best being the maximum of the number of nuclei with two neighbors (P = .002; Mantel-Cox test, 12.4). Multivariate analysis revealed that syntactic structure features did not provide additional prognostic values with regard to each other. However, they did show additional prognostic values with regard to the multivariate prognostic index (currently one of the best prognosticators in breast cancer), which combines the mitotic activity index, lymph node status, and tumor size. Measurement of syntactic structure features could therefore contribute to an improved prediction of prognosis of breast cancer patients. In conclusion, syntactic structure analysis is a simple, fast, and highly reproducible technique that shows prognostic value in invasive breast cancer and also has important prognostic value with regard to the well-established and prognostically strong morphometric features. It seems to be a promising new method of analyzing tissue architecture in breast cancer and perhaps in many other tumors.

Breast Neoplasms↗

PubMed1988

Reproducibility of two in vivo tests of platelet function.

We correlated repeat determinations of platelet aggregate ratios (PAR) and plasma beta-thromboglobulin (BTG) in the right and left arms of thirty-four subjects in order to measure test reproducibility and to evaluate the effects of venipuncture. The reproducibility of PAR on the same blood samples was relatively low but similar to that obtained when the right arm and left arm values were compared, thus indicating little variation secondary to venipuncture. For BTG, the reproducibility on identical blood samples was quite high, but fell significantly when plasma samples from the two sides were correlated. This finding and increased BTG values when obvious blood collection problems occurred, indicated that plasma BTG levels are quite sensitive to venipuncture technique.

Humans↗

PubMed1991

Ventilatory threshold during exercise in patients with mild to moderate chronic heart failure: determination, relation with lactate threshold and reproducibility.

Detection of the ventilatory threshold during exercise has been proposed in order to assess exercise tolerance in patients with chronic heart failure. The relation between the different methods of detecting the ventilatory threshold and the lactate threshold, however, and their reproducibility, have not really been assessed. Forty-three patients with chronic heart failure underwent an exercise test with respiratory gas analysis. A lactate threshold could be determined in 36 patients and a ventilatory threshold in 27 to 38 patients, depending on the method of determination of the ventilatory threshold. The greatest number of determinations (38) and the best correlation coefficient with the lactate threshold (r = 0.87 and 0.88, respectively) were obtained with the method of the ventilatory equivalent for oxygen and by averaging the different methods of determination. Reproducibility of the ventilatory threshold was only moderately good (r = 0.83) and less satisfactory than that of the peak oxygen uptake (r = 0.97). We conclude that unless the way of detecting the ventilatory threshold is improved in patients with chronic heart failure, the peak oxygen uptake will remain more reproducible.

Adult↗

PubMed1990

A validation study on the reproducibility of transcranial Doppler velocimetry.

The transcranial Doppler method for the measurement of intracranial arterial blood flow velocity is a useful noninvasive technique with a number of applications. The present study validated the reproducibility of this method for repeated measurements of flow velocity in the middle cerebral and basilar arteries. Fifteen healthy volunteers were studied. Measurements were made twice by one examiner and once by another in a single day and again by the first examiner on another day. The reproducibility was evaluated by calculating the correlation coefficient (r) and the coefficient of variation (CV) of the difference between the values obtained from each pair of measurements. Although depending on the examiner, the time interval between the examinations and the vessels studied some differences were noted in the reproducibility, both the r (0.69-0.95) and CV (6.7%-19.5%) values in the whole study were good enough to warrant the applicability of this method for the repeated measurements of the intracranial arterial blood flow velocity in future studies.

Cerebral Arteries↗