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PubMed1999

Rectal temperature time of death nomogram: sudden change of ambient temperature.

Cooling experiments on dummies known as body-like cooling were performed with sudden decrease and increase of ambient temperature in the order of 15 degrees C. In the case of a sudden decrease of ambient temperature, a second 'temperature plateau' occurs which is shorter than the known plateau at the beginning of body cooling. The cooling curves can be described mathematically by a three-step procedure based on the two-exponential term of the 'nomogram method'. The second plateau at the beginning of the second cooling phase in sudden decreased ambient temperature requires a lower value of the constant A (1.15) compared with the known value (1.25) at the beginning of body cooling. In the case of a sudden increase of ambient temperature in the order of 15 degrees C no procedure could be found to model the cooling curves mathematically.

Air↗
PubMed1999

The diameter of the common femoral artery in healthy human: influence of sex, age, and body size.

PURPOSE: To determine the relevance of dilatations of the common femoral artery (CFA), knowledge of the normal CFA diameter is essential. The diameter of the CFA in healthy male and female subjects of different ages was investigated. METHODS: The diameter of the CFA was measured in 122 healthy volunteers (59 male, 63 female; 8 to 81 years of age) with echo-tracking B-mode ultrasound scan. The influence of age, sex, height, weight, body surface area (BSA), and systolic blood pressure was analyzed by means of a multiple regression model. RESULTS: The CFA increased steadily in diameter throughout life. From 25 years onwards, the diameter was larger in men than in women. Significant correlations were found between the CFA diameter and weight (r = 0.58 and r = 0.57 in male and female subjects, respectively; P <.0001), height (r = 0.49 and r = 0.54 in male and female subjects, respectively; P <.0001), and BSA (r = 0.60 and r = 0.62 in male and female subjects, respectively; P <.0001). Age and BSA were used to create a model for prediction of the CFA diameter (r = 0.71 and r = 0.77 in male and female subjects, respectively; P <.0001). CONCLUSION: The diameter of the CFA increases with age, initially during growth but also in adults. This is related to age, body size, and sex male subjects have larger arteries than female subjects. It is now possible to predict the normal CFA diameter, and nomograms that may be used in the study of aneurysmal disease are presented.

Adolescent↗
PubMedDate not supplied

[Utilization of the pharmacokinetic parameters of acetylsalicylic acid for optimizing its use with people of different ages].

Nomograms for application of acetylsalicylic acid in persons of different age are presented. The nomograms are based on pharmacokinetic parameters of acetylsalicylic acid with regard to the age. Proceeding from the known constants of absorption and elimination, the nomograms are made use of to screen the loading and maintenance doses, to determine the time of administering the first maintenance dose and the maximal amount of the drug in the body, which was built up as a result of the use of the accepted treatment schedule. While using the nomograms one should be guided by the known therapeutic dose and the dosage intervals or by the therapeutic or maximal allowable dose. The nomograms are unsophisticated, fairly convenient, and help determine the optimal regimen of the use of acetylsalicylic acid in persons of different age.

Adult↗
PubMed1992

Relationship among age, serum cholesterol level and population percentile in adults.

The data of the National Health and Nutrition Examination Survey comprehensively have shown that distributions of serum cholesterol levels in the US adult population are age and sex dependent. General formulas were constructed and published by the author on the basis of the data of the National Health and Nutrition Examination Survey to predict the population percentile for serum cholesterol levels by age. A mathematical model and a computer program previously published by the author were employed in the study. Analysis of the computer-assisted predicted and the National Health and Nutrition Examination Survey-reported percentiles indicated that the designed program for calculating the formulas was accurate and reliable. The formula could determine the relationship among adult age, serum cholesterol level and population percentile. A comprehensive table and nomograms that show the relationship among age, serum cholesterol level and population percentile in men and women for each year group between 20 and 79 years of age are obtained in this study, using the previously published formulas. The population percentiles predicted by the formula may reflect the relative degrees of risk for coronary heart disease. The population percentile, simultaneously expressed as 'risk percentile', may be used as a parameter of risk assessment for coronary heart disease for all adult ages and sexes. Seventy-five population percentile of serum cholesterol level is suggested as a cutoff point of high 'risk percentile' for coronary heart disease. This information on the percentile may have a preventive diagnostic value for detection, evaluation and treatment of patients with high cholesterol levels. The comprehensive table and nomograms showing the relationship among age, serum cholesterol level and population percentile may be hopefully available to clinicians and useful in their medical practice and may also be helpful in future clinical investigation.

Adult↗
PubMed1978

USE OF A PROGRAMMABLE CALCULATOR IN CARDIOPULMONARY PERFUSION.

This study describes a hand-held, battery-powered, programmable instrument (Calculator Model SR-52) that can be taken directly into the operating room by cardiopulmonary perfusionists. Three programs are described in detail: 1) Cardiopulmonary perfusion parameters and estimated blood volume; 2) blood gas parameters and saturations, with temperature corrections; and 3) cardiopulmonary oxygen transfer and oxygenator efficiency. This inexpensive calculator allows perfusion personnel to manipulate easily-derived data into values which heretofore have required elaborate nomograms or special slide rules-or were not available within a reasonable computational time.

Journal Article↗
PubMed1991

Intra-ocular concentration-time relationships of subconjunctivally administered gentamicin.

Eighty-nine patients scheduled for cataract removal or lens implantation were divided randomly into three groups. Each received 5, 10 or 20 mg gentamicin subconjunctivally at times varying between 0.2 and 19 hours pre-operatively. At surgery a sample of aqueous humour was obtained and analysed for gentamicin concentration. The data for each group were subjected to non-linear regression analysis to fit an open one-compartment pharmacokinetic model with first-order kinetics. A statistically acceptable fit was obtained. The average values of the pharmacokinetic parameters obtained from the single doses were used to simulate multiple-dose kinetics. The average target intra-ocular gentamicin concentrations and dosage interval were specified in the computer program, which subsequently allowed calculation of the dose required. This allowed the construction of a simple linear nomogram that can be used to read off the dose needed for handling specific clinical situations.

Aged↗
PubMed2026

Factors associated with additional intervention requirement following ESWL in pediatric patients with urolithiasis.

OBJECTIVE: To identify predictors of additional intervention following extracorporeal shock wave lithotripsy (ESWL) in pediatric patients and to develop a clinically applicable predictive model. MATERIALS AND METHODS: This retrospective cohort study included 647 pediatric patients who underwent ESWL between 2015 and 2025. Demographic, clinical, and radiological variables were analyzed. Univariable and multivariable logistic regression analyses were performed to identify independent predictors of additional intervention. Model performance was evaluated using receiver operating characteristic curve analysis. RESULTS: Additional intervention was required in 65 patients (10.0%). On multivariable analysis, stone size 10-20 mm (OR: 3.04, p = 0.003), moderate (OR: 2.16, p = 0.049) and severe hydronephrosis (OR: 6.05, p < 0.001), and multiple stones (OR: 3.52, p = 0.030) were identified as independent risk factors. Increasing age (OR: 0.84, p = 0.026), history of urolithiasis (OR: 0.41, p = 0.006), and lower calyx location (OR: 0.14, p = 0.034) were associated with a reduced risk. The model demonstrated good discriminative performance (AUC: 0.794), with a sensitivity of 72% and specificity of 75%. Internal validation using bootstrap resampling demonstrated stable model performance, yielding a corrected AUC of 0.732. CONCLUSION: Stone burden, hydronephrosis severity, and stone multiplicity are key determinants of additional intervention after ESWL in pediatric patients. The proposed model shows good predictive performance and may support individualized risk stratification and clinical decision-making.

Humans↗
PubMed1983

[A graphic method for determining the refractive power of intraocular lenses].

A nomogram has been developed for determining the refractive power of emmetropic intraocular lenses. Individual deviations of optical dimensions from mean values, such as axis length, anterior chamber depth and corneal curvature are used to find a graphical solution. Errors of measurement of optical dimensions are analyzed with regard to their influence on the refractive power of an intraocular lens; errors in measuring the length of the axis have the greatest influence. The nomogram represents a simple method of determining the refractive power of an emmetropic lens. Furthermore, residual refraction can be determined if an intraocular lens of a given power is used or if postoperative ametropia is desired.

Eye↗
PubMed1999

A nomogram to evaluate intrinsic absorption rate constants of potential oral prolonged-release candidates.

The purpose of this study was to devise a simple method to determine whether or not a drug's absorption rate constant favored the selection of that drug for an oral prolonged-release drug delivery system (DDS). Computer simulations were used to observe the drug time-course in the DDS, the gastrointestinal tract, and the cumulative amount absorbed following administration of an 8-, 12-, and 24-hr zero-order DDS. For each DDS, the drug's intrinsic absorption rate constant, ka, was systematically varied from 0.1 to 10 hr-1. Results demonstrated that the DDS controlled the absorption rate whenever drug release was rate-limiting. However, the release rate did not determine the length of time that a DDS controlled the absorption rate. Instead, the duration of DDS-controlled absorption increased as the ka value increased. When ka > or = 2 hr-1, the DDS controlled more than 80% of the 8-, 12-, and 24-hr dosing intervals. Conversely, when ka < or = 0.12 hr-1, the DDS failed to control absorption. In conclusion, this investigation developed a technique to ascertain the rate-limiting step when a zero-order DDS releases a drug that undergoes first-order absorption. This technique was employed to construct a nomogram that allows its users to estimate the duration of control by an 8-, 12-, or 24-hr DDS based on the ka value for the drug.

Adsorption↗
PubMedDate not supplied

Predicting treatment dose for novel therapies using urea standard Kt/V.

Calculation of urea standard Kt/V (stdKt/V) as a dose measure for guiding novel hemodialysis or hemofiltration therapy prescription is complex since this parameter depends on the magnitude of posttreatment urea rebound. We propose here a two-step procedure for calculating urea stdKt/V from single-pool urea Kt/V values (spKt/V) determined from serum urea concentrations in pretreatment and posttreatment blood samples. First, the dependence of urea stdKt/V on equilibrated Kt/V (eKt/V) was derived from a fixed-volume single-pool model. Second, an empirical equation for predicting urea eKt/V from urea spKt/V values was determined using multiple linear regression and available data during 4-hour hemodialysis, 2-hour hemodialysis, and 2-hour hemofiltration treatments. This empirical (rate/dose) equation is likely more robust for novel therapies than other equations derived from only data during conventional (4-hour) hemodialysis treatments. The combination of these formulas allowed construction of nomograms for calculating urea stdKt/V from spKt/V during novel therapies. These principles were further illustrated by calculating the predicted treatment dose for daily (six times per week) hemofiltration therapy required to achieve a given urea stdKt/V.

Hemofiltration↗
PubMed1992

Phase II trial of suramin in patients with advanced renal cell carcinoma: treatment results, pharmacokinetics, and tumor growth factor expression.

Twenty-six patients with advanced renal cell carcinoma were treated with suramin administered by continuous infusion, with dosing determined by a nomogram. One patient achieved a partial response and five patients achieved a minor response or had stable disease for > 3 months. Toxicities included an immune-mediated thrombocytopenia in one patient and Staphylococcus sepsis that was not associated with neutropenia in five patients. Pharmacokinetic parameters were determined by the ADAPT II MAP-Bayesian parameter estimation program. Patient data were fit using a two-compartment open model and first-order rate elimination. This showed a wide interpatient variation in time to target level (median, 13.8 days), volume of distribution (median, 15.2 liters/m2), and t1/2-beta (median, 20.6 days). The patients who achieved a partial response, minor response, or stable disease had a slower elimination rate of suramin, compared to patients with progressive disease. Tumor specimens were obtained prior to therapy and were analyzed for the production of five different growth factor-specific RNA transcripts. These included transforming growth factor alpha, acidic fibroblast growth factor, basic fibroblast growth factor, and platelet-derived growth factor types A and B. No difference in the pattern of growth factor expression was seen in tumors of responding and nonresponding patients. Suramin does not have significant antitumor activity in renal cell carcinoma. The wide variability in pharmacokinetics suggests that individual dosing should be used in future trials of suramin for treatment for other malignancies. Pertinent corollary studies of tumor biology and clinical pharmacology should be included whenever possible in clinical trials in patients with renal cell carcinoma.

Adult↗
PubMed2004

Differentiating vascular pathophysiological states by objective analysis of flow dynamics.

BACKGROUND AND PURPOSE: There is an unmet need to classify cerebrovascular conditions physiologically and to assess cerebrovascular system performance. The authors hypothesized that by simultaneously considering the dynamic parameters of flow velocity, acceleration, and pulsatility index (PI) (impedance) in individual Doppler spectrum waveforms, they could develop an objective method to elucidate the pathophysiology of vascular conditions and classify cerebrovascular disorders. This method, dynamic vascular analysis (DVA), is described. METHODS: First, a theoretical model was developed to determine how any vascular segment and the ensemble of intracranial vascular segments could be defined according to its dynamic physiological characteristics. Next, the DVA method was applied to 847 anonymous serial complete clinical transcranial Doppler (TCD) studies of patients without regard for their diagnosis to ascertain actual reference ranges and the normality of the distribution curves for each dimension of the 3-parameter nomogram. The authors applied DVA to 2 clinical cases to see if they could track the changes in vascular performance of 2 known progressive diseases. RESULTS: The theoretical analysis identified 295,245 possible vascular states for the ensemble of vascular segments in the cerebral circulation. When applied to clinical TCD data, DVA revealed continuous, normally distributed data for the velocity, PI, and logarithm of the acceleration. CONCLUSIONS: DVA is proposed as a method for monitoring the physiological state of each cerebral artery segment individually and in ensemble. DVA evaluates the relationship among acceleration (force or pressure), velocity, and PI and provides an objective means to evaluate intracranial vascular segments using the paradigm of the well-described pressure-perfusion autoregulation relationship. DVA may be used to study cerebrovascular pathophysiology and to classify, evaluate, and monitor cerebrovascular disorders or systemic disorders with cerebrovascular effects.

Adult↗
PubMed2005

Urea clearance in dysfunctional catheters is improved by reversing the line position despite increased access recirculation.

BACKGROUND: Problematic or dysfunctional hemodialysis (HD) catheters are routinely reversed to achieve adequate blood flow for dialysis delivery. The purpose of the study is to determine the effect of varying blood pump speed (Qb) on access recirculation (AR), and urea clearance (K) in dysfunctional catheters in the normal and reversed positions. METHODS: Nineteen HD patients with tunneled cuffed catheters (5 functional and 14 dysfunctional catheters) were included; dysfunctional catheters are defined as the inability to attain a Qb of 300 mL/min or greater on 2 consecutive HD runs. AR and K measurements were obtained systematically for each catheter in the normal and reversed positions at increasing Qbs. K was measured using the ionic dialysance technique. RESULTS: In functional catheters, AR in the normal position was 0% and increased to 15% +/- 13% when reversed. Dysfunctional catheters had a greater AR of 25% +/- 16% when reversed. In functional catheters, there was no evidence of an increase in AR with increasing Qb irrespective of position. Similarly, there was no relationship between increasing AR and greater Qbs (r 2 = 0.10) in dysfunctional catheters. In dysfunctional catheters, when reversed, mean K increased from 128 +/- 10 mL/min at a Qb of 200 mL/min to 157 +/- 38 mL/min at maximal Qb (P < 0.05). CONCLUSION: We show that at increasing Qbs, K is improved in both functional and dysfunctional catheters. Data from the study are used to describe a nomogram to determine minimum Qb for a dysfunctional catheter in reversed position to maximize K.

Aged↗
PubMed1980

Using pharmacokinetics in drug therapy. VI: Comparing methods for dealing with nonlinear drugs like phenytoin.

Four methods for estimating dosage regimens for drugs exhibiting non-linear pharmacokinetic behavior (e.g., phenytoin) are described and compared. Estimations of phenytoin Vmax (maximum rate of drug metabolism) and Km (dissociation constant of drug-enzyme complex), and resulting dosage estimates arrived at by four methods were compared with values in six cases. All four methods provided pharmacokinetic estimates that shorten the period of dose titration and improve estimates of phentoin levels. Given a minimum amount of dose-versus-plasma-level data, all four methods provided reliable and comparable estimates of dosage regimens, although one method based on a nomogram sometimes estimated a narrower range of dosage regimens and plasma levels. When there is a potential for inaccuracy in the plasma-level-data, however, the estimated dosage regimens may be too unreliable for practical application.

Drug Administration Schedule↗
PubMed1998

Multivariate models as predictors of pathological stage using Gleason score, clinical stage, and serum prostate-specific antigen.

The patient presented is a 58-year-old man with newly diagnosed prostate cancer who likely has at least a 10- to 15-year life expectancy. In staging this man's extent of disease, several preoperative clinical variables are provided to assess whether the patient has local disease before offering definitive surgical therapy. It has been demonstrated that the combination of several of these variables in a multivariate analysis has greater predictive power than any of these variables do alone. Multivariate analysis using clinical stage, prostate-specific antigen (PSA), and Gleason score will provide both the physician and patient with 95% confidence intervals for determining the probability of having organ-confined disease, extracapsular penetration, seminal vesicle involvement, and lymphatic metastases. Several of the clinical variables given indicate that this patient has advanced disease, such as a PSA of 12 ng/mL, a stage T2b lesion, Gleason sum 7 disease in 2 of 3 cores from the right side associated with perineural invasion, and an additional Gleason sum 7 biopsy from the contralateral apex. For a man with these preoperative variables, there is a 13% chance of organ-confined disease, an 18% probability of seminal vesicle invasion, and a 17% chance of positive pelvic lymph nodes based on a nomogram constructed from multivariate analysis. Using this information, this man should be counseled that he has a high probability (87%) of extracapsular disease and a significant risk (15% to 20%) of having either seminal vesicle or lymph node involvement. Recognizing the risks and benefits of various forms of definitive therapy for prostate cancer, the patient has additional information to make an informed decision.

Humans↗
PubMed1985

Developmental assessment of spinal cord and cortical evoked potentials after tibial nerve stimulation: effects of age and stature on normative data during childhood.

Somesthetic information from lower extremities is processed by cerebral cortex after traversing the sensory pathways of peripheral nerve, spinal cord, brain-stem and thalamus. Clinical utility of somatosensory evoked potentials (SSEPs) during human development requires systematic analysis of normative data acquired during various stages of body growth and nervous system maturation. Accordingly, SSEPs after tibial nerve stimulation were studied in 32 normal awake children (1-8 years old) and compared with values obtained in young adults (18-40 years old). Potentials were recorded from the tibial nerve (N5), first lumbar spinous process (N14), seventh cervical spinous process (N20) and from the scalp, 2 cm behind the vertex (P28). In all children studied, the N5, N14 and N20 latencies were positively correlated with age and height yielding a predictive nomogram. An extremely variable electropositive cortical SSEP was recorded from Cz' which did not show a highly predictable linear relationship in association with a relatively poor correlation coefficient for height and age. It may be concluded that between 1 and 8 years of normal postnatal development, latencies reflecting peripheral nerve and lumbar spinal cord vary directly with height and age and can be represented by a simple cable model of a lengthening myelinated pathway. In contrast, the latency of the cortical SSEP reflects asynchronous maturation of elongating polysynaptic pathways and apparently requires a more complex model for prediction in order to enhance its clinical utility.

Adolescent↗
PubMed1983

Maintenance-dose prediction based on a single determination of concentration: general applicability to two-compartment drugs with reference to lithium.

A general approach to the selection of the maintenance dose (Dm) required to give a desired steady-state concentration of drug based on a single determination of concentration after a test dose (C*) is extended to drugs with two-compartment pharmacokinetic characteristics. Using the equation developed, the value of the proportionality factor relating 1/Dm to C was found to be within 3.2% of the value calculated from a published nomogram for lithium. The inherent error is shown to be a function of the value of the hybrid rate constants alpha and beta, as well as the value of an intercompartmental transfer rate constant, k21, in an individual.

Humans↗
PubMed2007

The value of different screening tests in predicting prostate biopsy outcome in screening for prostate cancer data from a multicenter study (ERSPC).

BACKGROUND: Although serum PSA testing is widely used as a screening test for prostate cancer (PC), it is known that it is not specific for PC. The study described here focuses on the value of screening tests next to PSA in identifying men with an elevated risk of having PC and the differences between three centers of the European Randomised study of Screening for Prostate Cancer (ERSPC). METHODS: The study population consists of 2,483 men with a PSA > or =4.0 ng/ml, all biopsied. We assessed data on age, serum PSA level at initial and repeat screening, prostate volume, number of positive DRE and TRUS findings, number of previous negative biopsies, and PPV of the three centers and overall. Using logistic regression analysis, predictors for biopsy outcome at repeat screening in men with a PSA value > or =4.0 ng/ml were determined on the complete dataset and per center. RESULTS: In 2,483 men biopsied, 665 cancers were detected (PPV = 26.8%). Data show that all predictors except prostate volume loose their predictive value in men previously biopsied. In men not previously biopsied, the predictive value of DRE and TRUS vary considerably among the three centers. CONCLUSIONS: Looking at the differences in the predictive value of screening tests in three "comparable" centers, generasibility is not as straightforward as it seems. Using a nomogram for predictive purposes developed elsewhere will require a thorough knowledge of the patient population of which it is derived, and one should interpret its results with a critical mind.

Aged↗