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At least 487 records · Page 27Linked to original sources
PubMed2005

Pattern of prostate-specific antigen (PSA) failure dictates the probability of a positive bone scan in patients with an increasing PSA after radical prostatectomy.

PURPOSE: Physicians often order periodic bone scans (BS) to check for metastases in patients with an increasing prostate-specific antigen (PSA; biochemical recurrence [BCR]) after radical prostatectomy (RP), but most scans are negative. We studied patient characteristics to build a predictive model for a positive scan. PATIENTS AND METHODS: From our prostate cancer database we identified all patients with detectable PSA after RP. We analyzed the following features at the time of each bone scan for association with a positive BS: preoperative PSA, time to BCR, pathologic findings of the RP, PSA before the BS (trigger PSA), PSA kinetics (PSA doubling time, PSA slope, and PSA velocity), and time from BCR to BS. The results were incorporated into a predictive model. RESULTS: There were 414 BS performed in 239 patients with BCR and no history of androgen deprivation therapy. Only 60 (14.5%) were positive for metastases. In univariate analysis, preoperative PSA (P = .04), seminal vesicle invasion (P = .02), PSA velocity (P < .001), and trigger PSA (P < .001) predicted a positive BS. In multivariate analysis, only PSA slope (odds ratio [OR], 2.71; P = .03), PSA velocity (OR, 0.93; P = .003), and trigger PSA (OR, 1.022; P < .001) predicted a positive BS. A nomogram for predicting the bone scan result was constructed with an overfit-corrected concordance index of 0.93. CONCLUSION: Trigger PSA, PSA velocity, and slope were associated with a positive BS. A highly discriminating nomogram can be used to select patients according to their risk for a positive scan. Omitting scans in low-risk patients could reduce substantially the number of scans ordered.

Bone and Bones↗
PubMed1999

Transverse cerebellar diameter on cranial ultrasound scan in preterm neonates in an Australian population.

OBJECTIVE: Fetal measurement of transverse cerebellar diameter (TCD) has been shown to correlate well with gestational age (GA), even in the presence of growth retardation. The aim of this study was to define the normal range of TCD in preterm neonates in an Australian population between 23 and 32 weeks GA. METHODOLOGY: Infants admitted to the Royal Women's Hospital, Melbourne, having routine cranial ultrasound scans (< 1500 g and/or of gestational age </= 32 weeks at birth) had their TCD measured on a cranial scan performed during the first 3 days of life. The posterior fossa was examined through the asterion using a General Electric LOGIQ 500 scanner (GE Medical Systems, Waukesha, USA) and TCD measurement was taken in the coronal plane. RESULTS: 106 infants < 1500 g and/or of GA </= 32 weeks at birth had their TCD measured between 1 January 1997 and 30 November 1997. Transverse cerebellar diameter and associated 95% confidence intervals are described for infants between 23 and 32 weeks GA. The linear regression equation relating TCD and GA was: TCD (mm) = -12.9 + 1.61 x GA (weeks). R2 = 0.80, P < 0.001. CONCLUSION: This is the only study of TCD measurement using cranial ultrasound in a group of preterm newborns, and forms the basis for nomograms of TCD which can be used as a tool to assist in the assessment of GA, even in growth-retarded preterm newborns, and in the diagnosis of cerebellar hypoplasia.

Cephalometry↗
PubMed1996

Preliminary noninvasive back-pressure recordings of bladder pressure.

Obstructive voiding is best evaluated with urodynamics, including bladder pressure and urine flow rates. Until recently, the recording of bladder pressure required the use of a urethral catheter. In preliminary observations, a noninvasive back-pressure method using an external condom catheter has been introduced to determine bladder pressure. This device uses a side tube for pressure recording and an outlet tube that is clamped for short periods of time. We have investigated design criteria for back-pressure recording techniques. In the laboratory setting using a plastic model, we determined that a low compliance condom is needed. In addition, a back flow of fluid during the clamping procedure helps to obtain quick back pressures and facilitates evaluation of pressure when low flow rates are present. These modified condom devices were evaluated in four male subjects. Back pressures were not statistically different than bladder pressures recorded with a urethral catheter. The use of back pressures in the evaluation for obstructive uropathy can be enhanced by using a pressure and flow nomogram.

Humans↗
PubMed1993

The weight-based heparin dosing nomogram compared with a "standard care" nomogram. A randomized controlled trial.

OBJECTIVE: To determine whether an intravenous heparin dosing nomogram based on body weight achieves therapeutic anticoagulation more rapidly than a "standard care" nomogram. DESIGN: Randomized controlled trial. SETTING: Two community teaching hospitals in Phoenix, Arizona, and Rochester, New York. PARTICIPANTS: One hundred fifteen patients requiring intravenous heparin treatment for venous or arterial thromboembolism or for unstable angina. INTERVENTION: Patients were randomized to the weight-based nomogram (starting dose, 80 units/kg body weight bolus, 18 units/kg per hour infusion) or the standard care nomogram (starting dose, 5000-unit bolus, 1000 units per hour infusion). Activated partial thromboplastin time (APTT) values were monitored every 6 hours, and heparin dose adjustments were determined by the nomograms. MEASUREMENTS: Activated partial thromboplastin times were measured using a widely generalizable laboratory method. The primary outcomes were the time to exceed the therapeutic threshold (APTT > 1.5 times the control) and the time to achieve therapeutic range (APTT, 1.5 to 2.3 times the control). Bleeding complications and recurrent thromboembolism were also compared. RESULTS: Kaplan-Meier curves for the primary outcomes favored the weight-based nomogram (P < 0.001 for both). In the weight-based heparin group, 60 of 62 patients (97%) exceeded the therapeutic threshold within 24 hours, compared with 37 of 48 (77%) in the standard care group (P < 0.002). Only one major bleeding complication occurred (in a standard care patient). Recurrent thromboembolism was more frequent in the standard care group; relative risk, 5.0 (95% CI, 1.1 to 21.9). CONCLUSIONS: The weight-based heparin nomogram is widely generalizable and has proved to be effective, safe, and superior to one based on standard practice.

Angina, Unstable↗
PubMed1981

Vancomycin therapy in patients with impaired renal function: a nomogram for dosage.

The relation between vancomycin clearance and renal function was studied in 22 patients with various degrees of renal functional impairment and in four normal volunteers. Clearance of vancomycin and creatinine were highly correlated (r = 0.92) among 17 persons not on dialysis. In five dialysis patients vancomycin clearance averaged 0.086 mL/min . kg of body weight (+/- SEM = 0.025). These relations enabled us to construct a nomogram for vancomycin dosage adjustment (based on a mean steady-state serum vancomycin concentration of 15 micrograms/mL) in patients with various degrees of renal functional impairment.

Adolescent↗
PubMed1986

Guidelines for external fixation frame rigidity and stresses.

Using results from FEM analyses and experiments as references, analytical methods are applied to develop simple approximate formulas to relate frame rigidity, maximal pin stresses, and peak pin-bone stresses in external fracture fixation (EFF) configurations in axial loading to the most important frame, pin, and bone parameters. It is found that, in a realistic range, the parameters can be adapted to vary the frame rigidity from about 13 N/mm to 17,000 N/mm, thereby reducing the maximal stresses in the pins and at the pin-bone interface by a factor of 140. In particular, when compromises have to be established in the frame characteristics in order to ensure a flexible configuration and limit the stress values at the same time, the formulas presented can provide useful guidelines. The side-bar separation and the pin modulus, in particular, can be adapted to decrease the rigidity, while only moderately increasing the stresses, thereby reducing changes for pin failure, pin-bone loosening, and pin-tract infection. A nomogram is presented for a quick reference to estimated relations between frame characteristics, rigidity, and stresses. It is believed that this material may be of use in EFF design and applications in clinical and animal experimental trials.

Biomechanical Phenomena↗
PubMed2002

Clinical predictors of androgen-independent prostate cancer and survival in the prostate-specific antigen era.

OBJECTIVES: To further characterize and identify novel predictors of androgen-independent prostate cancer (AIPC) and survival in the prostate-specific antigen (PSA) era. METHODS: A total of 184 consecutive patients with prostate cancer receiving chronic androgen suppression were assessed for the development of AIPC and overall survival. RESULTS: The median time to development of AIPC was 44 months (Stage M+ = 24 months; Stage M0 = 63 months, P = 0.000001). The 10-year overall survival rate for Stage M0 or M+ disease was 89% and 55%, respectively. AIPC developed significantly more commonly in patients with a higher nadir PSA level (greater than 1 ng/dL), a longer time to reach nadir PSA (greater than 3 months), a larger body mass index (greater than 27 kg/m2), greater pretherapy PSA level, and when evidence of metastatic disease was identified (logistic regression analysis). Overall survival was significantly associated with advanced stage (skeletal metastases), pretreatment PSA level, and history of skeletal fracture (multivariate Cox regression analysis). CONCLUSIONS: In the PSA era, longer intervals of androgen suppression therapy in nonmetastatic, biochemically recurrent prostate cancer have translated into a change in the duration of androgen-dependent prostate cancer. Although the duration of androgen dependence remains variable, prolonged--possibly "curative"--control exists in a subset of patients. Obese men developed AIPC significantly sooner than did slender men. A skeletal fracture was a significant negative predictor of overall survival. These observations form the basis for nomogram predictions of AIPC in the PSA era.

Aged↗
PubMed1996

A nomogram to predict the best biological half-life values for candidates for oral prolonged-release formulations.

It is sometimes possible to maintain plasma concentrations between desired maximum and minimum limits by repetitively administering a drug in an oral prolonged-release formulation when this goal cannot be achieved with a rapid-release formulation. However, this approach does not work with all drugs. The biological half-life value of the drug can be one cause for failure of this approach. Although it is recognized that a half-life may be too long or too short, neither the criteria for determining these values nor the consequences of failing to meet them have been established. The best half-life values for prolonged-release candidates were found by simulating once-a-day and twice-a-day administration of formulations and examining the capacity of these formulations to maintain steady-state plasma concentrations between various selected limits. These observations were used to establish criteria to judge the acceptability of half-lives. Half-life values were considered too long if drugs were self-sustaining and simulations of their rapid-release formulations were also successful. Half-life values were considered too short if minor variability in prolonged-release rates resulted in plasma concentrations above and/or below the selected limits. The actual half-life values that were considered too long or too short depended on the dosing interval and the selected maximum and minimum plasma concentrations. A nomogram was constructed to assess the acceptability of the biological half-life of a candidate for once-a-day or twice-a-day prolonged-release formulations. The nomogram employs the user-selected limits for the desired plasma concentrations to predict whether the half-life of a candidate is (1) too long, (2) too short, or (3) acceptable (i.e., between 1 and 2).

Administration, Oral↗
PubMed2002

Validation study of the accuracy of a postoperative nomogram for recurrence after radical prostatectomy for localized prostate cancer.

PURPOSE: A postoperative nomogram for prostate cancer was developed at Baylor College of Medicine. This nomogram uses readily available clinical and pathologic variables to predict 7-year freedom from recurrence after radical prostatectomy. We evaluated the predictive accuracy of the nomogram when applied to patients of four international institutions. PATIENTS AND METHODS: Clinical and pathologic data of 2,908 patients were supplied for validation, and 2,465 complete records were used. Nomogram-predicted probabilities of 7-year freedom from recurrence were compared with actual follow-up in two ways. First, the area under the receiver operating characteristic curve (AUC) was calculated for all patients and stratified by the time period of surgery. Second, calibration of the nomogram was achieved by comparing the predicted freedom from recurrence with that of an ideal nomogram. For patients in whom the pathologic report does not distinguish between focal and established extracapsular extension (an input variable of the nomogram), two separate calculations were performed assuming one or the other. RESULTS: The overall AUC was 0.80 when applied to the validation data set, with individual institution AUCs ranging from 0.77 to 0.82. The predictive accuracy of the nomogram was apparently higher in patients who were operated on between 1997 and 2000 (AUC, 0.83) compared with those treated between 1987 and 1996 (AUC, 0.78). Nomogram predictions of 7-year freedom from recurrence were within 10% of an ideal nomogram. CONCLUSION: The postoperative Baylor nomogram was accurate when applied at international treatment institutions. Our results suggest that accurate predictions may be expected when using this nomogram across different patient populations.

Adult↗
PubMed2000

The concept of cerebral circulatory-pressure index (CCPI).

The theoretical relations between blood pressure (MABP), intracranial pressure (ICP) and cerebral perfusion pressure (CPP) as well as the new Cerebral Circulation-Pressure Index (CCPI) are presented in the paper. The special nomogram collecting all of these parameters was constructed. CPPI was defined as a quotient of CPP and ICP: [formula: see text] CCPI reflects the relationship between the systemic MABP and ICP and for ensuring the normal conditions of intracranial circulation the MABP must be at least 4 divided by 5 times higher than ICP. The low values of CCPI, if they are not immediately corrected, results on severe brain disability or even death. We didn't find till now what should be the upper limit of CCPI, which overcrossing may be danger for the patient, especially with impaired autoregulation. Based on analysis of patients operated due to intracranial disorders as brain tumours, spontaneous and traumatic haematomas as well as ruptured aneurysms we find that the values of CCPI over 3 have a good prognosis, between 3 and 2 is a field for intensive treatment consisting on decreasing ICP or increasing the systemic blood pressure or both. If CCPI is below 1.5 the prognosis is pessimistic and all the patients died. CCPI together with the nomogram are useful in current evaluation of the state of patients and of the efficacy of treatment and prediction of the treatment results.

Adolescent↗
PubMed2006

Utility of a mathematical nomogram to predict delayed graft function: a single-center experience.

BACKGROUND: In 2003, Irish and colleagues published a weighted nomogram designed to predict the risk of delayed graft function (DGF) in a given transplant. It was anticipated that the predictive nomogram would permit preemptive therapies or allocation decisions based on the risk of DGF. The potential for reducing unfavorable outcomes and expenses appeared significant. This nomogram, however, was developed using population data found in the United States Renal Data System and has not been prospectively validated. METHODS: We evaluated the accuracy and utility of this nomogram in all cadaver renal transplants performed at a single transplant center. In addition, we correlated DGF with a variety of independent donor and recipient variables outside the established nomogram. RESULTS: The average nomogram DGF risk was 0.41 (a 41% chance of DGF) among the 169 cases in our population. The mean was 0.45+/-0.14 (confidence interval: 0.40-0.49) for the 42 DGF-positive subjects, and 0.40+/-0.14 (confidence interval: 0.38-0.43) for the 127 DGF-negatives (t=1.80; P=0.07). CONCLUSIONS: Although there was a trend showing the predictive value of the nomogram the overlap was tremendous, limiting the accuracy of the calculation for any single recipient. Prospective application of a nomogram on a case-by-case basis did not contribute meaningful information that could guide clinical decision-making regarding use, allocation or immunosuppressive regimen aimed at minimizing DGF.

Adult↗
PubMedDate not supplied

Major clinical events, signs and severity assessment scores related to actual survival in patients who died from primary biliary cirrhosis. A long-term historical cohort study.

BACKGROUND/AIMS: One of the prognostic methods for survival in primary biliary cirrhosis (PBC) is the Mayo model, with a time-scale limited to 7 years. The aim of our study was to assess how major clinical events, signs, several severity assessment methods and Mayo survival probabilities fit in with actual patient survival, by using yearly observations until 0.5 years before patient death from PBC. METHODOLOGY: Data of 32 patients dying from PBC were collected prior to death at -0.5, -1, -2 etc. years (median: -5 years, range: -16 to -0.5 years). Major events registered were: first occurrence of ascites, upper gastrointestinal bleeding or manifest hepatic encephalopathy and signs, first observation of spider naevi or purpura. Severity assessment methods applied (all with scores and classes) were: Mayo (M), Child-Campbell (C), Pugh-Child (P), Pugh-Child-PBC (PP), 'Child-Pugh' (CP), and Ascites Nutritional State-Child (ANS). Fifty percent survival estimates were calculated from Mayo scores. Severity assessment method variables were: ascites (C, P, PP, CP, ANS), encephalopathy (C, P, PP, CP), nutritional state (C, ANS), edema (M), age (M), serum albumin (M, C, P, PP, CP), bilirubin (C, M, P, PP, CP), and prothrombin time (M, P, PP, CP). RESULTS: In 27 out of 32 patients a major event occurred, always between -6 and -0.5 years (median: -1 year) and, never between -16 and -7 years (p < 0.0001). A sign was first observed in 30/32 between -14 and -0.5 years (median: -2 years). Compared to the total population, a sign, and even more so, an event indicated a shorter survival (p = 0.004 and p = 0.0002, respectively). The median 50% estimated survival (predicted by the Mayo model) fitted the actual survival from -6 to -0.5 years (r = -0.7, p < 0.0001), but not from -16 to -7 years (r = -0.1, p = 0.4). All -6 to -0.5-year severity scores correlated (p < 0.0001) both with actual survival (M, C, P, PP, and CP r = 0.7; ANS r = 0.5) and with estimated M 50% survival (C, P, PP, CP r = -0.9; ANS r = -0.6; M score: -0.99), but none with actual survival from -16 to -7 years, except for M, slightly (r = -0.3, p = 0.04). A nomogram for mean C, CP, M and ANS scores related to actual survival was constructed for the -6 to -0.5-year period. The C and CP classes A, B, and C did not appear to distinguish sufficiently into actual survival, whereas the M classes did. CONCLUSIONS: The occurrence of a major event appeared to exclude survival over 6 years. In these final 6 years, Child-Campbell, Mayo and Pugh scores correlated equally well with actual survival and better than Ascites/Nutritional State score. In our PBC patients, Campbell was an excellent alternative for Pugh; for Pugh, the original Child-Turcotte variable limits were fully sufficient.

Adult↗
PubMed1991

Distributions of oxygen, nutrient, and metabolic waste concentrations in multicellular spheroids and their dependence on spheroid parameters.

The distribution of oxygen, nutrients and metabolic wastes in multicellular tumor spheroids and its dependence on the parameters characterizing the spheroid (i.e., spheroid geometry, diffusivity, and consumption/production rates of biological substances) have been investigated by a theoretical analysis: 1. Parameter dependence is qualitatively demonstrated and visualized. 2. Reduction of the number of variables by specific coordinate transformations made it possible to generate nomograms from which concentration distributions for any choice of parameter values may easily be obtained. In particular, these nomograms may also be used for estimating concentration profiles of metabolic waste products, e.g. of lactate, which are expected to accumulate in the tumor spheroids. 3. An additional set of nomograms is given which is more convenient for determining time courses of these concentrations during spheroid growth. 4. A quantitative sensitivity analysis of parameter dependencies is performed to identify those parameters upon which a concentration of interest depends most critically in a given experimental situation.

Cell Aggregation↗
PubMed2006

Application of artificial neural network in prediction of bladder outlet obstruction: a model based on objective, noninvasive parameters.

OBJECTIVES: An artificial neural network model previously described by us that was based on lower urinary tract symptoms yielded a modest prediction of bladder outlet obstruction. The aim of this study was to establish another model, using more objective parameters, that could better predict for bladder outlet obstruction. METHODS: The records of 457 patients were used in the construction of the model. Of the 457 records, 300 were allocated to the training phase and 157 to the testing phase. All patients had the average flow rate, maximal flow rate, postvoid residual urine volume (PVR), and total prostate volume recorded. The results of the pressure flow study of those patients were considered the reference standard against which the artificial neural network was tested. RESULTS: Three models were tested. Models 1 and 2 were based on a three-output design (ie, nonobstructed, equivocal, and obstructed). The only difference was the number of iterations. The accuracy of the first model was 60.5% compared with 46.5% for the second. For a third model, in which the equivocal pressure flow study results were added to the nonobstructed group, the accuracy rose to 72%. Deletion of equivocal cases (around 19% of the total) was associated with an accuracy of 76% in the prediction of obstruction. CONCLUSIONS: An artificial neural network based on objective and noninvasive parameters could replace the pressure flow study in only 72% of cases. An accuracy of 76% in the detection of bladder outlet obstruction is rather impractical, because an equivocal zone has always been available on pressure flow study nomograms.

Humans↗
PubMed1994

[Normal weight of the brain in adults in relation to age, sex, body height and weight].

Based on more than 8000 autopsies of male and female patients without brain diseases the normal brain weight of adult males and females in relation to sex, age, body-weight, and body-height as well as Body Mass Index were calculated. The average brain weight of the adult male was 1336 gr; for the adult female 1198 gr. With increasing age, brain weight decreases by 2.7 gr in males, and by 2.2 gr in females per year. Per centimeter body height brain weight increases independent of sex by an average of about 3.7 gr. Body Mass Index is of minor importance and only relevant in males. Based on these data the independent variables, age and height, were for the first time combined in a nomogram for the calculation of brain weight. The mathematical functions were integrated in a computer program which facilitates the calculation of normal brain weights in individual cases.

Adult↗
PubMed2005

Evaluation of tonometric correction factors.

PURPOSE: To investigate the efficacy of currently available correction factors in correcting intraocular pressure (IOP) measurements for the errors induced by the normal variations in corneal structural characteristics. MATERIALS AND METHODS: Central corneal thickness (CCT) and corneal radius of curvature were measured on 324 individuals (175 normal: group 1 and 149 had either open angle glaucoma or ocular hypertension: group 2). IOP was measured in all normal subjects with the Goldmann applanation tonometer and the highest recorded IOP was obtained from patient charts for subjects with either open angle glaucoma or ocular hypertension. Regression analysis was performed on IOP, CCT, and corneal radius of curvature. The corrected IOP was also calculated using the models proposed by Ehlers and Orssengo and Pye. Linear regression analysis was used to calculate the residual association between corneal parameters and corrected IOP. RESULTS: There was a significant positive correlation between IOP measured using Goldmann applanation tonometer and the CCT in both groups. There was no significant correlation between corneal radius of curvature and IOP in either group. There was a significant negative correlation in both the groups between CCT and corrected IOP calculated using the models of Ehlers and Orssengo and Pye. This indicates that the Ehlers and Orssengo and Pye models may significantly overestimate the effect of CCT on IOP measurement. CONCLUSION: The effect of CCT and IOP as observed in the present study and by other studies in literature is less than predicted by both the Ehlers formula and the Orssengo and Pye model. Correcting IOP for the effect of CCT using these models could be erroneous and lead to overcorrection of IOP, thus resulting in erroneously low corrected IOP eyes with thicker cornea and erroneously high corrected IOP in eyes with thinner cornea.

Adult↗
PubMed1984

Estimation of gentamicin clearance and volume of distribution in neonates and young children.

Gentamicin therapy should be guided by serum level monitoring in all age groups, dosage adjustments depending on age related changes in pharmacokinetics. Population data analysed from two centres (43 infants from Glasgow and 100 infants and children from Manchester) by the computer program NONMEM showed that volume of distribution was related to body weight by a proportionality factor that decreased from the region of 0.41-0.46 l/kg in children less than 3 months to 0.25-0.32 l/kg in older children, a value which merges with that accepted for adults (0.25 l/kg). In both young and older children, clearance was also found to be dependent on body weight. Renal function (creatinine concentrations) provided no further explanatory power. When these results were used prospectively to forecast gentamicin concentrations with a Bayesian kinetic parameter estimation program, trough concentrations were more precisely predicted than peaks when a single concentration measurement was used. In clinical practice, however, two concentration measurements are usually routinely available and these should lead to greater precision of both peak and trough predictions. These results have been incorporated into a simple nomogram which can be used to determine a dose of gentamicin which will achieve target peak concentrations in infants, assuming that troughs should not exceed 2 micrograms/ml.

Age Factors↗
PubMed1978

Confirmation of a computer-derived nomogram to predict gentamicin serum concentrations in postsurgical patients.

The applicability of a previously reported nomogram to predict serum gentamicin levels in postsurgical patients was investigated. Seventeen patients accounting for 20 courses of gentamicin were studied. A total of 72 peak serum gentamicin levels were measured by a microbiological assay and compared with predicted serum levels determined by the dosing nomogram. Eighty-five percent of the measured peak gentamicin serum levels agreed with nomogram-predicted levels. This figure was reduced to 65% when certain unforeseen factors (i.e., patient interference with intravenous lines, dosage miscalculation and extra routes of gentamicin elimination) were identified. The nomogram is a particularly useful tool for the clinician to whom serum gentamicin levels are unavailable and who needs a method to predict serum gentamicin concentration based upon a given dosage.

Adult↗