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PubMed1985

Assessment of calcium homeostasis in the critically ill surgical patient. The diagnostic pitfalls of the McLean-Hastings nomogram.

Hypocalcemia is a common problem in critically ill surgical patients. We prospectively evaluated whether measurement of the total serum calcium (Ca) concentration or calculation of the serum ionized Ca level (by the McLean-Hastings nomogram) accurately reflects the measured serum ionized Ca level. Although 71% and 58% of 156 predominantly surgical intensive care unit (ICU) patients were hypocalcemic by the total serum Ca or calculated ionized Ca level, respectively, only 12% were hypocalcemic by directly measured serum ionized Ca measurement. The total serum Ca and calculated ionized Ca concentrations were sensitive (95% and 89%, respectively) but lacked specificity (32% and 46%, respectively) in predicting ionized hypocalcemia. Analyses of Ca binding to albumin in the serum of surgical ICU patients and normal subjects suggested that there is a circulating factor in critically ill patients that increases the binding of Ca to albumin. These observations may explain why the McLean-Hastings nomogram underestimates the protein-induced changes in serum Ca in critically ill surgical subjects. We conclude that: total serum Ca and calculated ionized Ca concentrations are poor indicators of the true serum ionized Ca status in critically ill surgical patients, and we recommend direct measurement of serum ionized Ca levels in these patients; and variability in the affinity of Ca for binding proteins in critical illness may explain the poor correlation between serum total and ionized Ca measurements.

Blood Proteins↗

PubMed1993

Nomograms of renal length in children obtained from DMSA scintigraphy.

The aim of this study was to establish nomograms of renal length in children comparing age, body weight, and height. Renal lengths were obtained from data derived from Tc-99m DMSA scintigraphy in 266 patients with 532 kidneys that appeared normal on DMSA studies. The children's ages ranged from 6 days to 19 years. Renal length appeared to have nonlinear relationships with patient weight and age, but was found to correlate linearly with patient height. On average, scintigraphic renal length exceeded sonographic renal length by approximately 1 cm. The most likely explanation for this is the effect of respiration causing renal motion during the acquisition of the scintigraphic images. It is hoped that the nomograms derived from these data will be of use in routine clinical practice for nuclear medicine departments performing DMSA scintigraphy in children.

Aging↗

PubMed1995

Dependence of male voiding efficiency on age, bladder contractility and urethral resistance: development of a voiding efficiency nomogram.

The influence of age, urethral resistance and bladder contractility on voiding efficiency was evaluated by pressure-flow studies in 138 men of a mean age of 60 years (range 18 to 86). From these studies the urethral resistance parameter was calculated and the maximum bladder contraction strength was determined. Premature fading of the bladder contraction was quantified by a bladder contraction strength decay factor. Voiding efficiency was expressed by the parameter of post-void residual urine volume as a percentage of the initial bladder volume. Multiple regression analysis showed that voiding efficiency depended significantly in descending order of importance on urethral resistance, maximum bladder contraction strength and bladder contraction strength decay factor. Patient age was not an independent factor. Maximum bladder contraction strength and bladder contraction strength decay factor were not correlated, suggesting that maximum bladder contraction strength and its decay constitute different properties of bladder contractile function. A voiding efficiency nomogram is proposed, making use of the values for maximum bladder contraction strength and urethral resistance in individual patients. Such a nomogram may have predictive value for the occurrence of acute retention but it must be tested prospectively.

Adolescent↗

PubMed1979

Predicting phenytoin dose - a revised nomogram.

The nomogram devised by Richens and Dunlop for predicting phenytoin dose has been tested in 127 residential epileptic patients, and the data obtained were used to prepare a revised version of the nomogram. In a further 78 patients, this new version was found to be superior to the original. The mean Km value was found to be 23.8 mumoles/liter. Km was independent of age and body surface area, but Dmax correlated positively with the latter two variables.

Adolescent↗

PubMed1995

Nomogram for estimating plasma unbound disopyramide concentrations in patients with varying plasma alpha 1-acid glycoprotein concentrations.

Since plasma protein binding of disopyramide (DP)--a class IA antiarrhythmic widely used in the prevention and treatment of various types of cardiac arrhythmias--is not only saturable within the therapeutic range but also altered under various pathophysiological conditions, the interpretation of total DP concentrations, Ctotal, measured during routine therapeutic drug monitoring (TDM) is often complicated. To circumvent this problem, we attempted to establish a comprehensive nomogram that allows estimation of unbound DP concentrations (Cu) based upon Ctotal of the drug and plasma concentration of alpha 1-acid glycoprotein (AAG), a major DP-binding protein. The nomogram was formulated with use of the in vitro binding data retrieved from 103 subjects categorized into 10 different groups each with a different mean concentration of AAG (range: 0.14-1.54 g/L). Data analysis, using a binding model assuming one specific binding site and nonspecific binding(s), revealed that alterations in plasma DP binding are attributable mainly to those in the capacity, Bmax, rather than affinity, ka, constant of the specific binding site. In addition, plasma AAG concentration correlated significantly (r = 0.90, p < 0.001) with the Bmax value over the range 0.09-2.28 g/L. For this reason, we substituted Bmax calculated by the regression equation as a function of AAG and the overall mean ka and nonspecific binding parameter values for the respective individual variables of the binding model, so that Cu of each plasma sample was estimated from the corresponding data on Ctotal and plasma AAG levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗

PubMed2004

Influence of dose, cigarette smoking, age, sex, and metabolic activity on plasma clozapine concentrations: a predictive model and nomograms to aid clozapine dose adjustment and to assess compliance in individual patients.

The measurement of plasma clozapine concentrations is useful in assessing compliance, optimizing therapy, and minimizing toxicity. We measured plasma clozapine and norclozapine (N-desmethylclozapine) concentrations in samples from 3782 patients (2648 male, 1127 female). No clozapine was detected in 291 samples (227 patients, median prescribed dose 300 mg/d). In 4963 (50.2 %) samples (2222 patients); plasma clozapine concentration ranged from 10 to 350 ng/mL.Step-wise backward multiple regression analysis (37 % of the total samples) of log10 plasma clozapine concentration against log10 clozapine dose (mg/d), age (year), sex (male = 0, female = 1), cigarette smoking habit (nonsmokers = 0; smokers = 1), body weight (kg), and plasma clozapine/norclozapine ratio (clozapine metabolic ratio, MR) showed that these covariates explained 48% of the observed variation in plasma clozapine concentration (C = ng/mL x 10-3) (P < 0.001) according to the following equation: log 10 (C) = 0.811 log 10 (dose) + 0.332 (MR) + 69.42 X 10 (-3) (sex) + 2.263 x 10 (-3) (age) + 1.976 x 10(-3) (weight) - 0.171 (smoking habit) - 3.180. This model and its associated confidence intervals were used to develop nomograms of plasma clozapine concentration versus dose for male and female smokers and nonsmokers. Predicted plasma clozapine changes by +48% in nonsmokers, +17% in females, +/-8 % for every 0.1 change in MR (reference 1.32), +/-4% for every 5 years (reference 40 years), and +/-5 % for every 10 kg body weight (reference 80 kg). The nomograms can be used (i) to individualize dosage to achieve a given target plasma clozapine concentration, and (ii) for quantitative evaluation of adherence by estimating the likelihood of an observed concentration being achieved by a given dosage regimen. The model has been validated against published data.

Adult↗

PubMed1993

Infusion nomograms.

Seven infusion nomograms are presented for the rapid and accurate composition of continuous infusions. The construction of these nomograms is described.

Algorithms↗

PubMed1978

Monitoring digoxin therapy: III. How useful are the nomograms?

1. A previously described set of guidelines for digoxin therapy has been evaluated in twenty-four patients. 2. Six different published methods (nomograms and equations) for predicting digoxin requirements have been studied to determine their clinical usefulness in the context of the twenty-four patients. 3. The limitations of the nomograms and equations are discussed.

Adult↗

PubMed1986

A comparison of graphical nomogram methods with a computerized Bayesian analysis method in the interpretation of serum phenytoin concentrations.

A study was performed to compare the predictability of a reported Bayesian graphical method, the drug nomogram used in the Bayesian Computer Method and the Driessen Nomogram with that of a computerized Bayesian analysis method in the interpretation of serum phenytoin concentrations. It was found that the results generated by the graphical method were similar to those of the computer with a mean prediction error of 3.9 mg/day in the dose to achieve a concentration at steady-state of 20 ml/l. Overall the results of the graphical method were less biased and had more precision with a significant improvement in relative precision (P less than 0.01) than the initial estimate or Driessen methods.

Adolescent↗

PubMed1989

Maximum and average urine flow rates in normal male and female populations--the Liverpool nomograms.

The study of voiding in men and women has been handicapped by the lack of a normal reference range covering urinary flow rates over a wide range of voided volumes. Normal volunteers (331 males and 249 females) were studied. Each voided once into a calibrated Dantec Urodyn 1000 mictiograph. On a second occasion 282 men and 46 women voided. The maximum and average urine flow rates of the first voids in both sexes were compared with the respective voided volumes. Nomogram charts, in centile form, for both the maximum and average urine flow rates were constructed using statistical transformations of the data. Males showed a significant decline in both urinary flow rates with age, although there was no statistically significant variation in either urine flow rate with respect to first versus repeated voiding. Females showed no statistically significant variation in either urine flow rate with respect to age, parity or first versus repeated voiding. The maximum and average urine flow rates in both sexes showed an equally strong relationship to voided volume. No artificial restriction of voided volume, e.g. minimum 200 ml, appeared appropriate. These nomograms offer reference ranges for both maximum and average urinary flow rates in both sexes covering a wide range of voided volumes (15-600 ml).

Adolescent↗

PubMed1990

Urine flow rates in male and female urodynamic patients compared with the Liverpool nomograms.

The Liverpool male and female nomograms provide normal reference ranges for the maximum and average urine flow rates over a wide range of voided volumes. A known urine flow rate, in combination with the respective voided volume (and in men the age), can be converted into an equivalent centile ranking, using the equation for the relevant nomogram. Centile rankings allow the urine flow rates of specific male and female populations to be compared. The maximum and average urine flow rates of urodynamic patients (504 consecutive male and 168 consecutive female) were converted into centile rankings. These centile rankings were then compared with the respective urodynamic diagnoses. The median centile rankings for their maximum and average urine flow rates were 21 and 11 (male) respectively and 31 and 18 (female) (vs 50 for the normal populations). The low urine flow rates applied to all diagnostic groups, including those symptomatic men and women who were found to be urodynamically normal. Low urine flow rates may be one of a number of subtle manifestations of urological disease in these patients. Men with obstruction and women with voiding difficulties had the lowest urine flow rates. The 25th centile (men) and the 10th centile (women) appeared to be most appropriate lower limits of normality for both urine flow rates to identify those men more likely to be obstructed and those women at higher risk of voiding difficulties. Men and women with detrusor instability had the highest urine flow rates. Detrusor instability was present in 71% of men with centile rankings for the maximum urine flow rate over 50; 50% of women whose maximum urine flow rate centiles were over 90 had detrusor instability.

Adolescent↗

PubMed1995

Maximum and average urine flow rates in normal children--the Miskolc nomograms.

OBJECTIVE: To establish normal reference ranges of urinary flow rates in children. SUBJECTS AND METHODS: From a screening programme, 200 healthy children (96 girls and 104 boys, between 3 and 18 years old) with no renal, urological, psychological or neurological disorders were selected, and they provided 433 micturitions for analysis. The children were divided into those with body surface areas of < 0.92 m2, between 0.92 and 1.42 m2 and > 1.42 m2. The voided volume, maximum and average flow rates of urine were measured. Data were fitted by several mathematical functions and goodness-of-fit determined. RESULTS: The relationship between maximal or average flow rates and voided volume was best fitted by a logarithmic function. The maximal and average urine flow rate nomograms are given in centile form for each body surface area group in both girls and boys. Flow rates showed a close relationship with voided volumes in both sexes and for all body sizes. The average maximal and average flow rates were higher in girls than in boys. CONCLUSION: Normal nomograms of maximal and average urine flow rates of girls and boys at three different body surfaces are presented in centile form. These may be useful for diagnosing lower urinary tract disturbances in children over a wide range of body size and voided volumes.

Adolescent↗

PubMed1980

Nomograms for precise determination of birth weight for dates.

We have derived a mathematical model (Altman and Coles, 1980) that matches closely the birth weight standards derived from the large Aberdeen survey (Thomson et al, 1968). From this, we have drawn nomograms that can be used to assess an infant's position in relation to these standards. The nomograms are easy to use and give adequate precision.

Birth Weight↗

PubMed1994

Body weight estimation of elderly patients by nomogram.

OBJECTIVE: To determine a safe and easy way to estimate body weight (BW) accurately in nonambulant elderly patients. DESIGN: An anthropometric study of ambulant patients. PARTICIPANTS: Two hundred eleven ambulant inpatients, 108 males and 103 females. SETTING: Inpatient departments of the University Department of Geriatric Medicine, Cardiff, Wales, UK. MEASUREMENTS: Skinfold thickness of chin, triceps, forearm, wrist, subscapular, sternal angle, waist, suprailiac, knee, and calf; circumference of arm, forearm, thigh and calf; body weight, chest girth, abdominal girth, upper limb length, leg length, and body weight. Measurements were carried out by means of Harpenden Skin-Fold Caliper, tape measure, and bathroom scale. RESULTS: Measured body weight in males was highly correlated with both arm circumference and chest girth. In females, measured body weight was highly correlated with waist skinfold thickness and thigh circumference. Nomograms for weight estimation in males and females were constructed from the regression equations for these measurements. CONCLUSIONS: Convenient estimation of body weight in nonambulant patients may be carried out using nomograms, which, themselves, may be used as progress sheets to assess the effect of dietary supplementation on body weight.

Aged↗

PubMed1981

Validity of the Astrand-Ryhming nomogram for predicting maximal oxygen intake.

The purpose of this study was to evaluate the validity of the predicted VO2 max from the Astrand-Ryhming nomogram, using the cycle ergometer as the sole exercise mode and following the recommended submaximal test protocol. In addition, two sets of age correction factors were compared for accuracy. Using the Astrand age correction factors, the SEE of the predicted VO2 max for the 40 male subjects was .42 L.min-1 or 5.7 ml.kg-1.min-1, (r = .76 and .83, respectively); there was no significant difference between the measured and the predicted means. Although virtually identical SEE and r were found when applying the von Dobeln age correction factors, a significantly lower predicted mean was found (p less than .05), which indicated a consistent tendency to underestimate the actual VO2 max. These results suggest that the Astrand age correction factors should be used in conjunction with the Astrand-Ryhming nomogram, especially when classifying subjects into various fitness classifications.

Adolescent↗

PubMed1973

Partograms and nomograms of cervical dilatation in management of primigravid labour.

Philpott's graphic labour has been modified and used in 15,000 labours; it has been unanimously accepted by the staff. A nomogram has been constructed to show the normal progressive dilatation of the cervix for primigravidae admitted at different stages of cervical dilatation. Retrospective evaluation of the nomogram showed that it can separate normal labour from labour destined to result in an abnormal outcome, such as longer first and second stages, a greater incidence of instrumental delivery, and babies with low Apgar scores.It is suggested that the use of a stencil representing normal labour progress, together with Philpott's partogram, will be of considerable use, both in specialist and in general-practitioner units.

Apgar Score↗

PubMed1991

Nomogram for the prediction of unbound phenytoin concentrations in patients on a combined treatment of phenytoin and valproic acid.

The interpretation of the total phenytoin (PT) concentration can be problematic if valproic acid (VPA) is given as a comedication, because VPA displaces PT from the protein binding sites and can increase the free fraction of PT. In order to estimate the free or unbound PT concentration (PTf) from the total PT concentration (PTt) and VPA concentration, a nomogram was constructed and evaluated. Data of 84 patients on combined therapy with PT and VPA were used in drawing up the regression equation (PTf = 0.0792.PTt + 0.000636.PTt.VPA) from which the nomogram was constructed. The predictions were checked using another 33 patients whose serum concentrations were determined in the morning and in addition several times during the day. The results show that using this method the PTf concentrations can be accurately estimated from the PTt and VPA concentrations.

Adolescent↗

PubMed1975

[Nomogram for the determination of arterial oxygen partial pressure of man in relation to high altitude and in dependence from age (author's transl)].

If somebody ascends from sea level to higher altitude within a short time, the change of the atmospheric conditions can be a danger for his life. Therefore, a nomogram was constructed which allows to read off the arterial oxygen partial pressures and the corresponding arterial oxygen saturation in relation to altitude. On the basis of the oxygen partial pressure of the atmosphere determined by steps of 500 m from sea level up to an antitude of 10,000 m, we calculated the decrease of the oxygen partial pressure from the inspired air to the arterial blood. When passing our airways, the inspired oxygen partial pressure is dimished by the adaptation to BTPS conditions and by the increasing CO2 partial pressure when approaching the alveolar gas exchanging zone. Another oxygen partial pressure gradient formed by inhomogeneities of ventilation to perfusion, diffusing capacity to perfusion and shunt perfusion is found at the alveolar-arterial barrier. The value of this alveolar-arterial oxygen partial pressure difference is closely correlated to age. With the values of the single steps, the nomogram was constructed. Seven abscissas show the oxygen partial pressure gradients from the inspired air at a distinct altitude to the arterial blood. In relation to a lot of CO2-depending oxygen dissociation curves, it is possible to read off additionally the corresponding arterial oxygen saturation for a person in rest up to an altitude of 10,000 m.

Adult↗