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PubMed1977

Controlled ventilation with the Mapleson D system A theoretical and experimental study.

A theoretical analysis has been performed to show the interrelationships between alveolar carbon dioxide concentration, carbon dioxide output, alveolar ventilation and fresh gas flow during controlled ventilation with the Mapleson D system. The model and forms of equation used have been substantiated by experiments in which dogs were ventilated through a coaxial version of the Mapleson D system at varying levels of fresh gas flow and alveolar ventilation. By assuming that man ventilated with this system behaves as does the dog, a nomogram has been produced to predict alveolar carbon dioxide concentrations at any levels of fresh gas flow and minute volume.

Anesthesia, Inhalation↗
PubMed1984

Application of hydrogel lens average thickness.

The equation for the average thickness of a hydrogel lens is a complex function. This report gives a simple method of estimating this parameter. By structuring the information into nomograms, an accurate system is derived which facilitates the design of a contact lens to provide a required average oxygen transmissibility. Several examples of the accuracy of the estimated value compared to the calculated value are shown. Details of the use of these nomograms are given with a discussion on the worth of an average thickness value as compared to a local thickness value.

Contact Lenses, Hydrophilic↗
PubMed1983

Estimating ideal body mass in children.

An equation and nomogram to estimate ideal body mass (IBM) for establishing dosage regimens of certain drugs in children was derived from a large pediatric data base. The data were from more than 20,000 U.S. children (ages 1-17 years) included in two major surveys published by the National Center for Health Statistics. The IBM was defined as the 50th percentile weight for a given height (ht). The equation derived was IBM(kg) = 2.396e0.01863(ht), where height is in cm. The IBMs estimated from this equation were compared with estimates from three other methods, two of which were derived from an adult population. The adult methods were unsuitable for pediatric use. This equation and nomogram for estimating IBM in children should be useful in determining dosage regimens of aminoglycosides and other drugs for obese pediatric patients.

Body Height↗
PubMed1997

How Chlamydomonas keeps track of the light once it has reached the right phototactic orientation.

By using a real-time assay that allows measurement of the phototactic orientation of the unicellular alga Chlamydomonas with millisecond time resolution, it can be shown that single photons not only induce transient direction changes but that fluence rates as low as 1 photon cell(-1) s(-1) can already lead to a persistent orientation. Orientation is a binary variable, i.e., in a partially oriented population some organisms are fully oriented while the rest are still at random. Action spectra reveal that the response to a pulsed stimulus follows the Dartnall-nomogram for a rhodopsin while the response to a persistent stimulus falls off more rapidly toward the red end of the spectrum. Thus light of 540 nm, for which chlamy-rhodopsin is equally sensitive as for 440-nm light, induces no measurable persistent orientation while 440-nm light does. A model is presented which explains not only this behavior, but also how Chlamydomonas can track the light direction and switches between a positive and negative phototaxis. According to the model the ability to detect the direction of light, to make the right turn and to stay oriented, is a direct consequence of the helical path of the organism, the orientation of its eyespot relative to the helix-axis, and the special shielding properties of eyespot and cell body. The model places particular emphasis on the fact that prolonged swimming into the correct direction not only requires making a correct turn initially, but also avoiding further turns once the right direction has been reached.

Animals↗
PubMed1994

A guideline nomogram to control intraoperative haemodilution in cardiac surgery.

Intraoperative blood collection prior to cardiopulmonary bypass (CPB) is a common procedure in cardiac surgery. Its aims are to obtain fresh whole blood to be infused after CPB, to use autologous blood in the prime or to avoid too high levels of haematocrit (HCT) during CPB. Calculations to determine the amount of blood to be collected are generally based on theoretical assumptions. In this paper we have set up and controlled, on a clinical basis, a nomogram to be used in order to obtain a standard pre-CPB HCT equal to 38%, using a moderately hypervolaemic haemodilution based on blood collection simultaneous with fluid replacement. Thirty adult patients were evaluated in order to settle the nomogram; subsequently, the nomogram validity was checked on 100 adult patients. Statistical analysis revealed the good clinical usefulness of this instrument.

Adult↗
PubMed1998

Factors predicting the diameter of the popliteal artery in healthy humans.

PURPOSE: To determine the relevance of popliteal dilatations, knowledge of the normal popliteal artery diameter is essential. This study investigates the diameter of the popliteal artery in healthy males and females. METHODS: We measured the diameter of the popliteal artery in 121 healthy volunteers (59 males and 62 females), ages 8 to 81, with echo-tracking B-mode ultrasonography. We analyzed the influence of age, sex, height, weight, body surface area (BSA) and systolic blood pressure with a multiple regression model. RESULTS: The popliteal artery increased steadily in diameter throughout life. From 25 years on, the diameter was larger in males than in females. If corrected for BSA, this difference decreased from 17% to 7%. This study found a correlation between popliteal artery diameter and BSA (r=0.47 and r=0.61, respectively, p < 0.0001). Age, followed by BSA, was the most influencing factor on popliteal diameter in both males and females (r=0.62 and r=0.66, respectively, p < 0.0001). We used age and BSA in creating a model for prediction of popliteal artery diameter. CONCLUSIONS: The diameter of the popliteal artery increases with age, initially during growth, but also in adults. This is related to age, body size and sex, with males having larger arteries than females. It is now possible to predict the normal popliteal arterial diameter, and nomograms are presented for use in the study of aneurysmal arterial disease.

Adolescent↗
PubMed1978

Acute response to acid-base stress.

A method previously established in the experimental animal for predicting the acute response to either metabolic stress (bicarbonate administration) or respiratory stress(manipulation of oxygenator gas during cardiopulmonary bypass) has been extended to man. The method is based on a single nomogram. The accuracy of the nomogram is demonstrated using data from 13 patients on cardiopulmonary bypass. Similar agreement obtains between the nomogram and data reported by others. The nomogram can be used to estimate the therapeutically required dose of bicarbonate.

Acid-Base Imbalance↗
PubMed1991

Graphic estimation of phenytoin dose in adults and children.

Two simple nomograms for individualizing the phenytoin dose in adults and children based on two or more steady-state plasma or serum levels (Css) at different daily doses are described. The nomograms allow one to plot, detect, and exclude abnormal points due to noncompliance, interactions, or laboratory errors, to draw the best line for the remaining points, and to estimate the dose necessary to reach a desired Css without calculations but with the same accuracy as more complex computer-dependent methods based on calculation of Vmax and Km. Our nomograms may be a practical aid in adult or pediatric practice.

Adolescent↗
PubMedDate not supplied

Comparison of different treatment strategies for diffuse large-cell lymphomas: a decision analysis.

There are more than 20 drug combinations in use for the treatment of diffuse large-cell non-Hodgkin's lymphoma (NHL). New treatments have been developed without prior comparison in clinical trials. The authors devised a Markov-process model to compare the efficacy of a first-generation combination chemotherapy regimen (CHOP) with that of a third-generation regimen (MACOP-B) using currently available data. For a typical 57-year-old male patient, life expectancy with MACOP-B was 12.1 years, compared with 8.3 years with CHOP. The remission rate after initial treatment and the functional status after the first remission is achieved were the most important determinants of life expectancy. It was still possible for CHOP to become better strategy provided that the initial remission rate with MACOP-B were lower than 50% or that functional status after remission was achieved were less than 66%. The analysis suggests that the most effective therapeutic regimen for diffuse large-cell lymphoma must not only result in a high remission rate but also cause minimal late sequelae. These two parameters were incorporated into the nomogram, which can serve as a basis for comparison of the efficacy of any chemotherapeutic regimen in non-Hodgkin's lymphoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Use of electron beam tomography data to develop models for prediction of hard coronary events.

BACKGROUND: Prediction of hard cardiac events (myocardial infarction and coronary death) remains difficult in spite of the identification of several relevant risk factors for the development of coronary artery disease (CAD). New indicators of risk might add to our predictive ability. We used measures of coronary artery calcification (CAC) found by electron beam tomography (EBT) imaging to develop prediction models for hard cardiac events alone and in association with traditional risk factors for CAD. METHODS: Two groups of patients were studied: group A, 676 asymptomatic patients (mean age 52 years, 51% men) prospectively followed up for 32 +/- 7 months after being referred by primary care physicians for a screening EBT, and group B, 10,122 asymptomatic patients screened by EBT at one center and used as controls for calculation of calcium score nomograms. RESULTS: The occurrence of hard events in group A patients was related to traditional risk factors for CAD, presence of CAC (score >0), Ln (1 + absolute calcium score [CS]), and age- and sex-specific CS percentiles (CS%). Univariate analyses showed that age, smoking, diabetes mellitus, presence of CAC, Ln (1 + absolute CS), and CS% were predictive of hard events (all P <.05). Multiple logistic regression analyses demonstrated that CS% was the only significant predictor of events and provided incremental prognostic value when added to traditional risk factors for CAD (chi-square, P <.001). In a comparison of receiver-operator characteristic curves for prediction of hard events, the area under the curve for CS% plus conventional risk factors and age was significantly larger than that obtained by use of traditional risk factors and age separately as predictors (0.84 vs 0.71, respectively, P <.001). Furthermore, the area under the curve of CS% alone was significantly larger than that of traditional risk factors and age combined (0.82 vs 0.71, P =.028). CONCLUSIONS: Patients are usually selected for EBT screening on the basis of the presence of conventional risk factors for CAD. However, an age- and sex-specific calcium score provides the best predictive model for the occurrence of hard coronary events and adds incremental prognostic information to conventional risk factors for CAD.

Aged↗
PubMed1995

Gender-specific second-trimester biometry.

OBJECTIVE: This study was designed to evaluate the significance of gender differences for commonly used biometric parameters obtained ultrasonographically from second-trimester euploid fetuses. STUDY DESIGN: Gender-specific linear regression equations were developed for gestational age dependent and independent biometry from second-trimester ultrasonographically normal singleton euploid fetuses by use of biparietal diameters and femur and humerus lengths. Regression lines for male fetuses were compared with those for females by determining overlap of 95% confidence intervals at specific points. RESULTS: A total of 288 male fetuses (mean gestational age 16.7 +/- 1.0 weeks) and 251 female fetuses (mean gestational age 16.8 +/- 1.2 weeks) (not significant) were evaluated. Small statistically significant gender differences in fetal biometry were identified. The largest gender difference for gestational age-dependent parameters was a biparietal diameter difference of 1.15 mm at 21 weeks. The largest gender difference for gestational age-independent parameters was a femur length difference of 1.7 mm at a biparietal diameter of 50 mm. CONCLUSION: Statistically, but not clinically, significant gender differences of small magnitude exist for second-trimester fetal biometry, suggesting that gender-specific nomograms may be of limited value.

Biometry↗
PubMed2003

Re-evaluation of the dose to the cyst wall in P-32 radiocolloid treatments of cystic brain tumors using the dose-point-kernel and Monte Carlo methods.

Intracavity instillation of beta-emitting colloid pharmaceuticals is a common technique used to treat cystic brain tumors. Most of the dosimetric calculations that have been reported in the literature for this problem are based on empirical formulas derived by Loevinger. Concentration of P-32 radiolabeled solution for the delivery of a prescribed dose (200 Gy to the cyst wall) has been published previously using this formalism in what we refer to as a standard nomogram. The calculations using the Loevinger formulas for calculating the P-32 activity necessary to achieve 200 Gy at the cyst wall is re-evaluated and compared to numerically computed results based on full Monte Carlo simulations (EGSnrc) and the dose-point-kernel (DPK) integration method. For cyst diameters greater than 1 cm, the new calculations agree well with previously published results (the standard nomogram) to within a few percents. However, for cyst diameters of less than 1 cm, it is shown that the standard nomogram results underestimate the therapeutic activity by a factor of approximately 3 for very small diameters (approximately 0.2 cm). New tables based on our calculations are presented and the sources of discrepancies are identified. It is concluded that the new set of data based on our calculations should replace the standard nomogram to administer accurately the target dose to the cyst wall for the smaller diameter cysts (< 1 cm).

Beta Particles↗
PubMed1981

Transfusion nomogram: an application of physiology to clinical decisions regarding the use of blood.

A nomogram has been prepared that depicts relationships between cardiac output (Q), oxygen consumption (Vo2), hemoglobin concentration (Hb), the position of the oxygen-hemoglobin dissociation curve, the oxygen saturation of arterial blood (SaO2), and the partial pressure of oxygen in the mixed venous blood (PVO2). Examples are provided to illustrate how this nomogram may be employed to facilitate decisions regarding the need for blood transfusions in patients in whom oxygen delivery may be impaired.

Blood Transfusion↗
PubMed2004

Gleason grading and prognostic factors in carcinoma of the prostate.

Gleason grade of adenocarcinoma of the prostate is an established prognostic indicator that has stood the test of time. The Gleason grading method was devised in the 1960s and 1970s by Dr Donald F Gleason and members of the Veterans Administration Cooperative Urological Research Group. This grading system is based entirely on the histologic pattern of arrangement of carcinoma cells in H&E-stained sections. Five basic grade patterns are used to generate a histologic score, which can range from 2 to 10. These patterns are illustrated in a standard drawing that can be employed as a guide for recognition of the specific Gleason grades. Increasing Gleason grade is directly related to a number of histopathologic end points, including tumor size, margin status, and pathologic stage. Indeed, models have been developed that allow for pretreatment prediction of pathologic stage based upon needle biopsy Gleason grade, total serum prostate-specific antigen level, and clinical stage. Gleason grade has been linked to a number of clinical end points, including clinical stage, progression to metastatic disease, and survival. Gleason grade is often incorporated into nomograms used to predict response to a specific therapy, such as radiotherapy or surgery. Needle biopsy Gleason grade is routinely used to plan patient management and is also often one of the criteria for eligibility for clinical trials testing new therapies. Gleason grade should be routinely reported for adenocarcinoma of the prostate in all types of tissue samples. Experimental approaches that could be of importance in the future include determination of percentage of high-grade Gleason pattern 4 or 5, and utilization of markers discovered by gene expression profiling or by genetic testing for DNA abnormalities. Such markers would be of prognostic usefulness if they provided added value beyond the established indicators of Gleason grade, serum prostate-specific antigen, and stage. Currently, established prognostic factors for prostatic carcinoma recommended for routine reporting are TNM stage, surgical margin status, serum prostate-specific antigen, and Gleason grade.

Adenocarcinoma↗
PubMed1983

An azlocillin dosing nomogram for renal insufficiency.

We have developed an azlocillin dosing nomogram suitable for use in patients with various degrees of renal functional impairment. A total of 50 kinetic studies undertaken by us and an additional 60 similar kinetic investigations as reported in the literature formed the basis for the construction of our nomogram. This renal failure dosing nomogram gives immediate information to the physician who needs to give azlocillin to a patient with renal failure.

Azlocillin↗
PubMed1987

A nomogram for the interpretation of acid-base data.

A diagnostic nomogram based on log pCO2 and log cHCO3- as coordinates is presented. The significance areas for compensated acid-base disorders are indicated. The nomogram facilitates the recognition of mixed acid-base disorders. The graph is being used for on-line plotting.

Acid-Base Equilibrium↗
PubMed2003

Technical-methodological report: a nomogram for peak leg power output in the vertical jump.

Leg power is an important component in assessing both performance-related and health-related fitness. The Lewis equation and nomogram have been used for years to estimate leg power. A recent evaluation of the Lewis equation and further research led to the development of the Sayers equation. This equation provides an estimate of peak leg power, which has greater relevance than average power. Our purpose was to provide a simple and effective nomogram for calculating peak leg power output. The Sayers equation was transformed to an alignment nomogram and evaluated for facility of use and accuracy. The resultant alignment nomogram is easy to use and generates values for peak leg power in the vertical jump, which are well within the precision of the regression equation (r > 0.9999, CV < 0.2%). Interobserver error was less than 0.3% with a correlation of 0.9999. The Keir nomogram provides a simple and effective representation of the Sayers equation for use in both performance-related and health-related fitness assessments.

Adult↗