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PubMed1988

ND: YAG nomogram dosimetry scale for the bladder.

Bowel perforation and damage to surrounding organs is probably the most significant risk with the use of Nd-YAG laser in the bladder. To prevent this unwanted damage, a nomogram dosimetry scale was developed by delivering different settings of laser energy via a cystoscope to 25 female pigs. One week following treatment, exploratory laparotomy and cystectomy were performed. Microscopic analysis of the depth of laser irradiation was accomplished. From this study it was learned that, although the greater the energy delivered, the deeper the tissue damage, this is not uniform. Pulsed energy produced a deeper effect than continuous energy. The use of 30 watts of either pulsed or continuous energy for no longer than 15 seconds (450 joules) or 10 watts of either form of energy for less than 30 seconds (300 joules) did not produce bowel perforation. Other different combinations of high number of watts or pulses translated into transmural necrosis of the bladder with or without perforation and with or without bowel injury. Other factors such as density, thickness, color and temperature of tissue, type and wave length of laser and optimal focusing played a significant role in the final outcome. Useful information for human clinical use may be extrapolated from this experimental model.

Animals↗

PubMed1979

The flow rate nomogram: I. Development.

In normal individuals the flow rate depends on the initial bladder volume in a non-linear fashion. A flow rate nomogram taking this relationship into account was developed as an aid in the interpretation of urinary flow rate data. With this approach excellent differentiation of normal from obstructed individuals was achieved. In addition, the variability in a single individual's flow rate over time was estimated to be relatively small and, thus, uroflowmetry may be used to identify changes in outflow resistance after medical or surgical therapy.

Adult↗

PubMed1986

A dosing nomogram for continuous infusion intravenous naloxone.

Naloxone hydrochloride is extremely valuable for diagnosing and managing the opioid overdose. Due to naloxone's short half life and a long duration of action of most opioids, repeated naloxone dosing often is required to prevent the recurrence of respiratory depression. An alternative to repeated bolus administration is a continuous IV infusion. We conducted a two-phase study to determine the pharmacokinetics of naloxone and to develop a continuous dosing nomogram. In the first phase seven patients were given an IV bolus dose alone and serial plasma naloxone levels were determined. Naloxone elimination was found to be biexponential with the mean beta half life equal to 0.023 +/- 0.002 reciprocal minutes in two patients and 0.015 +/- 0.02 reciprocal minutes in five patients. In the second phase ten volunteers were given either a 2-mg or a 4-mg bolus dose followed by a 1.5-mg/hr or a 3-mg/hr continuous infusion. The mean volume of distribution of the central compartment was found to be 0.806 +/- 0.408 L/kg. The mean beta rate constant of elimination was found to be 0.036 +/- 0.027 reciprocal minutes. A computer simulation of the pharmacokinetic parameters determined in our study found that a continuous infusion of two-thirds of the bolus dose that resulted in reversal each hour will maintain the plasma naloxone levels equal to or greater than the naloxone levels that would have existed 30 minutes following the bolus dose.

Adult↗

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↗

PubMed2002

Percutaneous coronary interventions in octogenarians in the American College of Cardiology-National Cardiovascular Data Registry: development of a nomogram predictive of in-hospital mortality.

OBJECTIVES: We sought to evaluate the results of percutaneous coronary intervention (PCI) in elderly patients in contemporary practice. BACKGROUND: Prior studies of PCI in the elderly population demonstrate increased in-hospital mortality, but these studies are limited by small population size. METHODS: Using the American College of Cardiology-National Cardiovascular Data Registry (ACC-NCDR) of 100,253 patients, the in-hospital outcomes in all 8,828 PCI procedures performed on octogenarians were evaluated. Patients underwent PCI between 1998 and 2000 at over 145 participating centers. RESULTS: The mean age was 83.72 +/- 3.02 years, with female preponderance (53%). The PCI was considered angiographically successful in 93%, stents were placed in 75%, and the post-PCI length of stay was 3.3 +/- 5.1 days. Overall in-hospital mortality was 3.77% but was only 1.35% in PCI without recent myocardial infarction (MI) within one week (p < 0.0001). Patients having PCI within 6 h of the onset of their MI had an increase in mortality tenfold (13.79%) compared with patients without a recent MI (p < 0.0001). All groups that were defined based on time of PCI after MI onset up to seven days had increased mortality (all p < 0.0001). Older age (odds ratio [OR] of 1.03 per incremental year), depressed ejection fraction (EF) (OR 0.69 per 10 points for EF <60%), and time of PCI after MI onset (<6 h, OR 6.87; 6 to 24 h, OR 5.66; 24 h to one week, OR 2.93) were most strongly predictive of outcome by multivariate analysis. The predicted mortality from the multivariate model correlated well with the observed in-hospital mortality up to 20% mortality. A 254-point nomogram was constructed employing the logistic model using a weighted point system. CONCLUSIONS: In patients > or = 80 years old, PCI has good success and acceptable mortality. The presence of an acute or recent MI substantially increases the risk of in-hospital death.

Age Factors↗

PubMed2003

Prostate implant nomograms for the North American Scientific 103Pd seed.

Palladium-103-(103Pd) seed has been increasingly used in prostate implantation as either definitive or boost therapy because of its shorter half-life and higher initial dose rate. Because a growing number of radiation oncologists prefer real-time implantation in the operating room, it will be helpful if the total activity of the seeds can be determined based on the gland size before the patient is taken to the operating room. Based on our clinic data, nomograms have therefore been developed for one of the widely used 103Pd seeds, the MED3633 seed, which is produced by North American Scientific, Inc. (NASI). The total activities for implant volume ranging from 15 cc to 55 cc are provided for both seed "monotherapy" and seed boost.

Brachytherapy↗

PubMed1998

A model for collaboration in quality improvement projects: implementing a weight-based heparin dosing nomogram across an integrated health care delivery system.

BACKGROUND: At Aurora Health Care, an integrated delivery system based in Milwaukee, a system-level clinical quality improvement department was established in 1995 to facilitate collaboration on clinical quality improvement (QI) initiatives. THE COLLABORATIVE MODEL: A model was developed to use expertise within the system and avoid unnecessary duplication of efforts, while maintaining buy-in for the project's interventions at the point of service delivery. It was believed that a single team could design the improvement efforts or guidelines, and then work at a more local level with a different group of people to implement the processes. APPLYING THE MODEL TO THE HEPARIN QI PROJECT: Anticoagulation with heparin is considered the mainstay of treatment for pulmonary embolism and deep venous thrombosis. However, a large gap was found between present anticoagulation practices and published best practice in regards to achieving a key process measure. To reduce the overall time to achieving effective anticoagulation, a system-level team created an intervention primarily consisting of a preprinted order sheet, including the weight-based heparin dosing nomogram, and an education plan for physicians and other health care professionals. Significant improvement was observed at all pilot sites with overall rates of adequate anticoagulation within the first 24 hours improving from 73% to 95%. DISCUSSION: The system was able to standardize care at four of its five major hospitals and provide for better patient outcomes to a larger segment of the community, and then to replicate the heparin project to four additional sites during a six-month period. This model has been successfully applied to other quality improvement projects.

Anticoagulants↗

PubMed1994

A prospective randomized comparison of the accuracy of computer-assisted versus GUSTO nomogram--directed heparin therapy.

Failure to adequately anticoagulate the blood of patients receiving recombinant tissue plasminogen activator (TPA) leads to greater rates of rethrombosis. In a multicentered, randomized trial in 51 patients we compared the ability to achieve and maintain therapeutic anticoagulation by use of computer-assisted heparin therapy or the GUSTO (Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries) heparin nomogram guidelines in patients with myocardial infarction treated with recombinant TPA. Heparin therapy was initiated with either computer-generated starting doses or GUSTO guideline starting doses. Activated partial thromboplastin times were measured every 6 to 8 hours for the first 24 hours. The therapeutic range used in this trial was 1.5 to 2.5 times the patient's baseline activated partial thromboplastin time (APTT). Ninety-four percent of the APTT ratios in the computer group were equal to or greater than 1.5 in the first 24 hours compared with 78% in the GUSTO group (p < 0.009). No significant difference in bleeding was found (7.7% for GUSTO; 4.2% for computer). Incremental time-dependent changes in heparin dose were found (day 1, 1110 +/- 243 units/hr, APTT ratio = 2.5 +/- 1.4; day 3, 1380 +/- 374 units/hr, APTT ratio, 1.9 +/- 0.4). Computer-assisted heparin therapy TPA results in superior anticoagulation accuracy compared with the GUSTO guidelines. In addition, the pharmacodynamic response to heparin changes in the 2 to 3 days after administration of TPA, leading to greater heparin requirements.

Aged↗

PubMed1995

Barbiturate withdrawal--a nomogram for supplementary dosing after the phenobarbitone loading technique.

A case of a woman who presented with a multiple drug overdose and then subsequently had a withdrawal syndrome complicated by seizures and delirium highlights the seriousness of the barbiturate withdrawal syndrome. The patient had a short elimination half-life for phenobarbitone and required supplementary phenobarbitone doses to prevent and treat these complications. We have devised a nomogram which in conjunction with serum levels allows a rapid determination of whether and how much supplementary doses are required during barbiturate withdrawal.

Journal Article↗

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↗

PubMed1982

Aminoglycoside dosing in renal transplant patients. Comparison of nomogram and individualized pharmacokinetic methods in patients with shifting renal function.

Serum amikacin concentrations were compared in infected renal transplant recipients that were compared in infected renal transplant recipients that were dosed using a creatinine-based nomogram (group I) or an individual computer-assisted pharmacokinetic dosing method (group II). A total of 30 treatment courses were administered. Mean postinfusion peak levels were 22 microgram/ml in group I and 23.4 microgram/ml in group II. Mean serum trough levels were 8.8 microgram/ml and 5.5 microgram/ml in groups I and II, respectively. Both peak and trough serum levels were significantly more often in the acceptable therapeutic (peak 20-32 microgram/ml) and nontoxic (through less than 10 microgram/ml) ranges in group 11 patients. Seventy-seven per cent of group II and 38% of group I peak levels were in the therapeutic range, while 87% of group II and 70% of group I trough levels were less than 10 microgram/ml. Ototoxicity developed with similar frequency in both groups and occurred significantly more often with a peak level greater than 32 microgram/ml. Declining renal function, usually as a result of allograft rejection, occurred in seven (44%) group I and only three (25%) group II patients but could not be exclusively related to amikacin in any patient. A serum trough level of greater than 10 microgram/ml was associated with an increased risk of declining renal function independent of other risk factors. Failures of aminoglycoside therapy are frequently associated with inadequate serum levels. Conversely, ototoxicity and nephrotoxicity may be related to elevated serum aminoglycoside concentrations. For these reasons, the computer-assisted pharmacokinetic dosing method should be used in septic surgical patients whose renal function is subject to sudden and unexpected changes.

Adolescent↗

PubMed1975

A nomogram for computing BP/IOP ratios.

Clinical estimates of ocular blood flow, based on a comparison of systemic blood pressure and intraocular pressure, appear to be better predictors of glaucomatous visual field loss than are tonometric estimates alone. One index of ocular hemodynamic status is the blood pressure/intraocular pressure ratio (BP/IOP). A nomogram is presented to aid in calculating this index.

Blood Pressure↗

PubMed1985

Nomogram for bretylium dosing in renal impairment.

Bretylium (Bretylol), an antiarrhythmic agent, is currently being used in the prophylaxis and treatment of patients with life-threatening ventricular fibrillation and tachycardia not responsive to conventional therapy. Because bretylium has a delayed onset of action that commonly causes hypotension and may increase ventricular irritability, its use in patients (especially patients with renal impairment) must be exercised with caution. Our results show that the maximum plasma concentration (Cmax) observed at the end of bretylium infusion, when normalized to the dose, increases significantly as renal function diminishes. Significant reductions in renal and total body clearance of bretylium have been observed in patients with renal insufficiency. In order to minimize the risk of potential toxicity following multiple dosing in such patients, dosage adjustments are necessary. Based on correlations developed between the total body clearance of bretylium and renal function, we present a nomogram herein that can be effectively used for adjusting the dosage of bretylium in patients with renal impairment.

Adult↗

PubMed2003

Nomogram for spherical RGP contact lens fitting in patients with pellucid marginal corneal degeneration (PMCD).

PURPOSE: To present a nomogram for spherical rigid gas-permeable (RGP) contact lens fitting in patients with pellucid marginal corneal degeneration (PMCD). METHODS: Retrospective review of the medical records of 24 patients diagnosed with PMCD who underwent an RGP contact lens trial at the Bausch & Lomb contact lens center between April 1995 and March 2002 at L.V. Prasad Eye Institute in Hyderabad, India. Data collected included age and sex of patients, duration of presenting symptoms, associated ocular conditions, presenting visual acuity, and degree of astigmatism. For the purpose of analysis, the astigmatism was classified into four groups: group 1, less than 5.00 diopters (D); group 2, 5.00 to 10.00D; group 3, 10.00 to 15.00D; and group 4, 15.00 to 20.00D. The final lens parameters, the patient's comfort level, and the duration of follow-up were analyzed. RESULTS: Forty eyes of 24 patients were fitted with RGP contact lenses during the study period. Sixteen were male patients and eight were female patients. The age of the patients ranged from 13 to 59 years, with a mean of 35.5 years. Twenty-two (91.7%) patients had typical inferior PMCD, whereas the other two (8.3%) had superior PMCD. The mean corneal curvature was 7.1 mm (range, 5.9-7.8 mm) in group 1, 6.9 mm (range, 6.6-7.9 mm) in group 2, 7.5 mm (range, 6.5-7.8 mm) in group 3, and 7.9 mm (range, 6.8-7.8 mm) in group 4. The mean base curve of the final fitting lens was 6.3 mm (range, 5.7-7.8 mm) in group 1, 6.8 mm (range, 5.9-7.8 mm) in group 2, 7.5 mm (range, 6-8.2 mm) in group 3, and 7.2 mm (range, 6.6-7.8 mm) in group 4. The mean lens diameter of the final fitting lens was 8.7 mm (range, 8.6-10.6 mm) in group 1, 9.5 mm (range, 8.8-10.5 mm) in group 2, 10.2 mm (range, 8.8-11.5 mm) in group 3, and 10.4 mm (range, 8.8-11.3 mm) in group 4. The common fluorescein patterns were central touch with midcentral peripheral pooling in 14 (35%) and dumbbell pattern in seven (17.%). The final visual acuity range with an RGP lens in the four astigmatism groups was 20/40 to 20/20 in group 1, 20/30 to 20/20 in group 2, 20/40 to 20/20 in group 3, and 20/200 to 20/50 in group 4. Twenty-one patients were comfortable with an RGP lens, and the mean duration of follow-up was 13 months. Three patients discontinued lens wear. In one patient, the lens was not stable, and the other two experienced discomfort with their lenses. CONCLUSIONS: Spherical rigid gas-permeable lenses are a good option for patients even with advanced PMCD. In patients with astigmatism of less than 10D, a lens with a base curve of 6.0 to 7.0 mm and a diameter of 8.0 to 9.5 mm seems to be a good initial lens for trial, and for patients with astigmatism of more than 10D, a lens with a base curve of 7.0 to 7.5 mm and a diameter of 10.0 to 10.5 mm seems to be a good initial lens.

Adolescent↗

PubMed1995

The Hayek oscillator. Nomograms for tidal volume and minute ventilation using external high frequency oscillation.

The Hayek Oscillator is a recent development in external high frequency ventilation and is a useful mode of ventilatory support during anaesthesia, in chronic respiratory failure and weaning in intensive care. The Hayek Oscillator is new and its application is growing, as are the number of patients who have benefited from its use. However, there are no clear guidelines on how best to adjust the oscillator to achieve optimum ventilation. A simple method of predicting changes in tidal volume and minute ventilation following adjustment would make the oscillator more useful. We present nomograms for tidal volume, minute ventilation and effective alveolar ventilation when the three variables, oscillator frequency, mean chamber pressure and peak-to-trough pressure span were adjusted. The frequency-tidal volume relationship was unaffected by a mean chamber pressure of 0, -5, -10 cmH2O, but altered with changes in peak-to-trough pressure span. We have also determined the effect of increasing negative extrathoracic pressure on functional residual capacity. The relationship between tidal volume and frequency was non-linear and related to the peak-to-trough pressure span. Mean functional residual capacity significantly increased from 2.25 l (SEM 0.10) without the cuirass at rest to 2.61 l (SEM 0.14) at -10 cmH2O (p < 0.05; n = 5) and 2.47 (SEM 0.12) at -20 cmH2O of mean chamber pressure. Vital capacity was unchanged by increasing extrathoracic pressure as was total lung capacity.

Adult↗

PubMed1982

Re-examination of digoxin dosage regimen: comparison of the proposed nomograms or formulae in elderly patients.

1 Comparison of measured trough serum digoxin concentrations (SDC) with those predicted at steady-state by forty sets of previously described pharmacokinetic equations in conjunction with either measured or estimated creatinine clearance (Clcr) was made in an elderly group of patients with varying Clcr (25-89 ml/min) who received maintenance digoxin therapy. 2 Mean values of day-to-day variation (% coefficient of variation) for serum creatine and measured Clcr examined three times within a week in 7 of 40 elderly patients were 6.42 and 8.36% respectively, while this value for SDC was 12.46%. 3 There was a statistically significant correlation (r = 0.72 to 0.79, P less than 0.001, n = 40) between measured Clcr and that estimated from three different methods. Siersbaek-Nielsen's nomogram approach gave the best correlation. 4 The calculated correlation coefficient values between measured and predicted SDC lay within a relatively narrow range but were weak (r = 0.443-0.628). Prediction error analysis, however, allowed us to determine the best set of pharmacokinetic equations for a first approximation to appropriate digoxin maintenance dosage requirements, namely Gault-estimated elimination rate constant, measured Clcr, and Jusko-estimated volume of distribution.

Aged↗

PubMed1975

A study of the pharmacokinetics of phenytoin (diphenylhydantoin) in epileptic patients, and the development of a nomogram for making dose increments.

Phenytoin is metabolized to its parahydroxylated derivative by hepatic microsomal enzymes. This hydroxylation is a saturable process, that is, the rate of metabolism fails to increase in proportion to the serum concentration. This leads to a nonlinear relationship between the maintenance dose of the drug and the resulting steady-state serum level. As the therapeutic range of serum levels is reached, the increase in level produced by a given increment in dose becomes progressively greater. An increment of only 50-100 mg will carry the serum level from the lower to the upper limit of the therapeutic range in most patients. Thus, problems in bioavailability, noncompliance, and drug interactions are an important practical problem with this drug. Monitoring serum phenytoin levels during chronic therapy is an invaluable therapeutic aid, enabling dosage adjustments to be made in order to achieve a level within the therapeutic range. A nomogram is presented in this paper in order to assist the physician in making dosage increments.

Adolescent↗

PubMed2002

Genetic and environmental influences on exceptional longevity and the AGE nomogram.

To live beyond the octogenarian years, population and molecular genetic studies of centenarian sibships indicate that genetic factors play an increasingly important role as the limit of life span is approached. These factors are likely to influence basic mechanisms of aging that in turn broadly influence susceptibility to age-related illnesses. Lacking genetic variations that predispose to disease as well as having variations that confer disease resistance (longevity enabling genes) are probably both important to achieving exceptional old age. The AGE (aging, genetics, environment) nomogram is introduced as an illustrative construct for understanding the influence of environmental and genetic factors on survival to various ages, depending on variations in the hypothesized relative importance of genes and environment to longevity. The rapid rise in the incidence of centenarians could indicate that many more people than we originally thought have the optimal set of genetic factors necessary to get to 100 and beyond. Recent studies indicate the likelihood that such factors will be elucidated in the near future.

Aged↗