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PubMed1998

Standards of birth weight in twin gestations stratified by placental chorionicity.

OBJECTIVE: To establish fetal growth nomograms for twin gestations, categorized by placental chorionicity, and to compare them with those of published singleton and twin nomograms. METHODS: Computerized data files of live births of all twins delivered between January 1990 and October 1996 at Saint Peter's Medical Center were used. Birth weight curves corresponding to the fifth, tenth, 50th, 90th, and 95th percentiles were derived separately for twins with monochorionic and dichorionic placentation. We generated the curves by applying the method of generalized estimating equations, after adjusting for the potential intracluster correlation due to twinning. The curves were then smoothed on the basis of nonparametric restricted cubic splines to derive (smoothed) birth weight percentiles. We then compared our twin birth weight nomogram to six previously published singleton and two twin nomograms published previously for predicting small for gestational age infants (defined as birth weight below the tenth percentile). RESULTS: Among 1302 twin fetuses, 272 (21%) were monochorionic. Twins from monochorionic gestations weighed, on average, 66.1 g (standard deviation 28.4 g, P = .02) less than twins from dichorionic gestations after correcting for gestational age. Twin curves based on parity (nulliparity versus multiparity) were not different from each other. Analyses indicate that all previously published singleton nomograms approximate twin growth reasonably well between 32 and 34 weeks, but they underestimate twin growth at earlier gestational ages (between 25 and 32 weeks) and overestimate twin growth beyond 34 weeks' gestation. Similarly, a comparison of previously published twin nomograms with those of ours indicates that the growth standards in our population were similar to those in other published twin nomograms. CONCLUSION: We recommend that future epidemiologic and clinical studies use twin nomograms to identify growth-restricted twin fetuses. Moreover, because fetal growth is influenced by placental chorionicity, we recommend that fetal growth assessment in twin gestations consider placental chorionicity, whenever the information is available.

Birth Weight↗

PubMedDate not supplied

Determination of ventilatory minute volumes for normocapnic ventilation under anaesthesia in healthy adults.

BACKGROUND: Mechanical ventilation under anaesthesia needs to be controlled to maintain normal oxygen and carbon dioxide tensions in the blood and to economize on fresh gas flows. Various ventilation nomograms such as Radford's nomogram and Nunn's CO2 predictor are based on data from studies, some of which do not mimic the conditions which prevail under anaesthesia. We, therefore, planned a study to formulate nomograms for normocapnic ventilation for anaesthetized adult subjects. METHODS: Two hundred and fifty-three patients with normal pulmonary function tests, scheduled for elective non-thoracic surgery were studied. Subjects were ventilated with a Siemens Servo 900 B ventilator using CO2 analyser 930 (Siemens-Elema Sweden) to adjust the minute volume sufficient to maintain end-tidal carbon dioxide fraction (FE,CO2) at around 5.5 normocapnia (PaCO2 5.06-5.6 kPa). This was confirmed with arterial blood gas analysis. RESULTS: The mean (SD) ventilation required for male patients was 6.123 (0.91) L [105 (13.1) ml/kg]. This was significantly higher than the requirement for female patients [5.262 (0.82) L; 98.7 (13.3) ml/kg]. The minute volume requirements showed a significant correlation with weight (W), height (H), body surface area, body mass index and other combinations of weight and height such as W x H, W/H, W2, W3 and H/W1/3. Nomograms were constructed for different weights and heights of males and females using multiple regression analysis. These minute volumes were found to be significantly higher than those calculated according to Radford's nomogram as well as Nunn's CO2 predictor and significantly lower than the Adelaide ventilation guide. CONCLUSION: The differences obtained in our nomograms are probably because the earlier ones were based on minute carbon dioxide production and physiological dead space data obtained from widely differing studies, some of which did not resemble conditions prevailing under anaesthesia. None of these used strict inclusion criteria such as pulmonary function tests. These may also be due to a difference in body structure between the subjects studied. Therefore, minute volume requirements calculated based on available western nomograms should not be applied to Indian subjects for normocapnic ventilation under anaesthesia.

Adolescent↗

PubMed1997

Combination of prostate-specific antigen, clinical stage, and Gleason score to predict pathological stage of localized prostate cancer. A multi-institutional update.

OBJECTIVE: To combine the clinical data from 3 academic institutions that serve as centers of excellence for the surgical treatment of clinically localized prostate cancer and develop a multi-institutional model combining serum prostate-specific antigen (PSA) level, clinical stage, and Gleason score to predict pathological stage for men with clinically localized prostate cancer. DESIGN: In this update, we have combined clinical and pathological data for a group of 4133 men treated by several surgeons from 3 major academic urologic centers within the United States. Multinomial log-linear regression was performed for the simultaneous prediction of organ-confined disease, isolated capsular penetration, seminal vesicle involvement, or pelvic lymph node involvement. Bootstrap estimates of the predicted probabilities were used to develop nomograms to predict pathological stage. Additional bootstrap analyses were then obtained to validate the performance of the nomograms. PATIENTS AND SETTINGS: A total of 4133 men who had undergone radical retropubic prostatectomy for clinically localized prostate cancer at The Johns Hopkins Hospital (n=3116), Baylor College of Medicine (n=782), and the University of Michigan School of Medicine (n=235) were enrolled into this study. None of the patients had received preoperative hormonal or radiation therapy. OUTCOME MEASURES: Simultaneous prediction of organ-confined disease, isolated capsular penetration, seminal vesicle involvement, or pelvic lymph node involvement using updated nomograms. RESULTS: Prostate-specific antigen level, TNM clinical stage, and Gleason score contributed significantly to the prediction of pathological stage (P<.001). Bootstrap estimates of the median and 95% confidence interval of the predicted probabilities are presented in the nomograms. For most cells in the nomograms, there is a greater than 25% probability of qualifying for more than one of the pathological stages. In the validation analyses, 72.4% of the time the nomograms correctly predicted the probability of a pathological stage to within 10% (organ-confined disease, 67.3%; isolated capsular penetration, 59.6%; seminal vesicle involvement, 79.6%; pelvic lymph node involvement, 82.9%). CONCLUSIONS: The data represent a multi-institutional modeling and validation of the clinical utility of combining PSA level measurement, clinical stage, and Gleason score to predict pathological stage for a group of men with localized prostate cancer. Clinicians can use these nomograms when counseling individual patients regarding the probability of their tumor being a specific pathological stage; this will enable patients and physicians to make more informed treatment decisions based on the probability of a pathological stage, as well as risk tolerance and the values they place on various potential outcomes.

Decision Support Techniques↗

PubMed2006

"Random" gentamicin concentrations do not predict trough levels in neonates receiving once daily fixed dose regimens.

BACKGROUND: Monitoring plasma gentamicin concentrations in neonates 24 hours after a once daily dose (4 mg/kg) often necessitates additional blood sampling. In adults a nomogram has been developed enabling evaluation of gentamicin doses by sampling concentrations with other blood tests, 4-16 hours after administration. We attempted to develop a similar nomogram for neonates. METHODS: In addition to standard 24 hour sampling to monitor trough concentrations, one additional "random" gentamicin concentration was measured in each of 50 neonates < 4 days of age (median gestation 33 weeks [28-41]), when other blood samples were clinically necessary, 4-20 hours after gentamicin administration. 24 hour concentrations of > 1 mg/L were considered high, and an indication to extend the dosing interval. RESULTS: Highest correlation (r2 = 0.51) of plasma gentamicin concentration against time (4 to 20 hours) was with logarithmic regression. A line drawn 0.5 mg/L below the true regression line resulted in all babies with 24 hr gentamicin concentrations > 1 mg/L having the additional "random" test result above that line, i.e. 100% sensitivity for 24 hour concentrations > 1 mg/L, though only 58% specificity. Having created the nomogram, 39 further babies (median gestation 34 weeks [28-41]), were studied and results tested against the nomogram. In this validation group, sensitivity of the nomogram for 24 hr concentrations > 1 mg/L was 92%; specificity 14%, positive predictive value 66%, and negative predictive value 50%. Prematurity (< or = 37 weeks) was a more sensitive (94%) and specific (61%) indicator of high 24-hour concentrations. 62 (87%) of 71 preterm babies had high 24-hour concentrations. CONCLUSION: It was not possible to construct a nomogram to predict gentamicin concentrations at 24 hours in neonates with a variety of gestational ages. Dosage tailored to gestation with monitoring of trough concentrations remains management of choice.

Age Factors↗

PubMed2004

An alternative analysis of intraoperative parathyroid hormone data may improve the ability to detect multiglandular disease.

HYPOTHESIS: A nomogram based on regression analysis of intraoperative parathyroid hormone level decay discriminates single gland disease from multiglandular (MG) disease more accurately than the currently used 50% rule. DESIGN: Retrospective case series. SETTING: Academic health center. PATIENTS: Two hundred thirty-five patients (222 patients with single gland disease and 13 patients with MG disease) who underwent parathyroidectomy. INTERVENTIONS: Intraoperative parathyroid hormone level analysis at baseline, time 1 (about 5 minutes), and time 2 (about 10 minutes) after excision of the first gland. MAIN OUTCOME MEASURES: The mean slope was calculated at time 1 and time 2 and analyzed using one-way analysis of variance and the Fisher least significance difference post hoc tests using data normalized to baseline intraoperative parathyroid hormone levels to compare patients with single gland disease with patients with MG disease. A regression-based nomogram was created to analyze individual kinetic decay data. RESULTS: The mean (SEM) single gland disease slope was significantly steeper than the MG disease slope at both time 1 (-0.91 [0.02] vs -0.66 [0.05]; P<.01) and time 2 (-0.77 [0.01] vs -0.56 [0.05]; P<.01). When the standard threshold rule of a 50% decrease from baseline was used, only 23% of the patients with MG disease were correctly predicted by intraoperative parathyroid hormone values (77% false-positive result rate) at time 1. However, the nomogram correctly predicted 54% of the patients with MG disease at time 1 (46% false-positive result rate). At time 2, the standard threshold 50%-rule method correctly predicted 38% of the patients with MG disease (62% false-positive result rate), while the nomogram still correctly classified 54% of the patients with MG disease (46% false-positive result rate). CONCLUSIONS: A regression-based nomogram incrementally improves prediction of MG disease compared with the standard 50%-rule method and accounts for variability in the exact timing of samples. Slope analysis suggests that the earliest time point best isolates the kinetics of the excised gland. The nomogram will need to be validated prospectively.

Academic Medical Centers↗

PubMed1997

Color Doppler ultrasound, pregnancy-induced hypertension and small-for-gestational-age fetuses.

OBJECTIVE: The nomogram of blood velocity flow resistance of the spiral arteries was built at 13-25 gestational weeks. Thereafter, by using the nomogram we tried to assess the results of the color Doppler examination of the uteroplacental circulation at the second trimester to predict pregnancy-induced hypertension (PIH) and small-for-gestational-age (SGA). METHODS: Two groups of patients were studied. Group 1, for the establishment of the nomogram, included 175 uncomplicated pregnancies with gestational ages ranging from 13-25 weeks. The Doppler flow waveforms of the spiral arteries were measured once for each pregnancy in the studies. Group 2 consisted of 305 singletons selected consecutively for prospective study to confirm the occurrence of PIH or SGA. They were scanned twice for the measurements of the spiral artery waveforms at 13-19 and 20-25 weeks, respectively to test which gestational weeks interval in the nomogram is most sensitive in predicting PIH and SGA. RESULTS: The 5th, 50th and 95th percentiles of the pulsatility index (PI) values of the nomogram at the second trimester were used as the cut-off points to predict pregnancies complicated with SGA or PIH at delivery. Using the receiver operator curve, the 50th percentiles of the PI values of the nomograms were chosen as predictives for the development of PIH and SGA. At 13-19 gestational weeks, the specificities in predicting PIH and SGA were 50.71% and 49.82%, respectively, and the sensitivities were 52.00% and 50.00%, respectively. The calculated Cohen's Kappa statistics were 0.008 and 0.001, respectively in predicting PIH and SGA. At 20-25 gestational weeks, the specificities in predicting PIH and SGA were 49.64% and 49.46%, respectively, and the sensitivities were 56.00% and 57.14%, respectively. The calculated Cohen's Kappa statistics were 0.017 and 0.022, respectively in predicting PIH and SGA. CONCLUSION: The measurements of uteroplacental blood flow velocity waveforms at the second trimester are not sensitive enough to be an early screening tool for PIH and SGA in the low risk, non-selected pregnancy population. The fact suggests that in most gravidas complicated with PIH and SGA, the physiological process of trophoblastic invasion in the spiral artery was not prevented before the 25th gestational week.

Blood Flow Velocity↗

PubMed2002

Doppler assessment of the uterine circulation in the second trimester in twin pregnancies: prediction of pre-eclampsia, fetal growth restriction and birth weight discordance.

OBJECTIVE: To compare singleton nomograms of the uterine circulation with previously established twin nomograms in the prediction of pre-eclampsia, fetal growth restriction (FGR), and birth weight discordance > or = 20% in twin gestations. METHODS: This was a retrospective analysis of maternal and perinatal data obtained from 256 dichorionic twin pregnancies. The mean uterine artery resistance index was calculated from both sides and the presence and absence of notching was recorded. Cut-off levels for abnormal flow parameters were the 95th centile of reference ranges of either singleton or twin nomograms. RESULTS: According to twin reference values, 14.0% of patients were screen positive, compared to only 3.1% when singleton reference values were used. The sensitivity of abnormal uterine artery Doppler results defined by twin nomograms vs. singleton nomograms was 36.4% vs. 18.2% for pre-eclampsia, 26.7% vs. 9.7% for FGR, 28.9% vs. 7.9% for birth weight discordance > or = 20%, and 26.5% vs. 10.3% for any adverse outcome, respectively. CONCLUSION: Despite using specially constructed twin nomograms, uterine artery Doppler studies in twin gestations had an overall low sensitivity in predicting adverse obstetric outcome. Negative predictive values of uterine Doppler studies in twin gestations are lower compared to those reported in unselected singleton pregnancies, i.e. maternal and fetal complications occur more frequently despite normal uterine artery waveforms. This suggests that there is an additional pathomechanism, causing pre-eclampsia and FGR in twin gestations, that is unrelated to uteroplacental insufficiency.

Adult↗

PubMed2003

Validity of cuff-uroflow as a diagnostic technique for bladder outlet obstruction in males.

OBJECTIVE: To investigate the validity of the cuff-uroflow method as a diagnostic technique for bladder outlet obstruction (BOO) in males. MATERIAL AND METHODS: A cross-sectional study was carried out on a consecutive series of 93 males (mean age 54.1 years) referred on presenting with lower urinary tract symptoms. The patients were subjected to measurement of the isovolumetric pressure (Pcuff.op) and its corresponding flow (Qcuff.op) by means of the cuff-uroflow method. Subsequently, a study was carried out of the conventional pressure-flow, calculating the degree of BOO according to the provisional International Continence Society (ICS) nomogram. RESULTS: There was a statistical relationship between the Pcuff.op and Qcuff.op values and the degree of BOO according to the provisional ICS nomogram: patients with BOO had a lower value of Qcuff.op and a higher value of Pcuff.op than those without BOO. Using a logistic regression model a nomogram was constructed to link Pcuff.op with Qcuff.op. This nomogram was divided into three areas (obstructed, indeterminate and not obstructed). Most patients (44.1% of the sample) were situated in the indeterminate area. If those patients were excluded, the nomogram gave a sensitivity for the diagnosis of obstruction of 100% and a specificity of 55.6%. The overall rate of correct diagnosis was 84.6%. CONCLUSIONS: The parameters obtained using the cuff-uroflow method were related to the presence of BOO. According to the provisional ICS nomogram, this method showed a better sensitivity than specificity for the diagnosis of BOO.

Adult↗

PubMed2005

The umbilical cord thickness measured at 18-23 weeks of gestational age.

OBJECTIVE: To establish an umbilical cord thickness nomogram from anatomy ultrasound scans performed between 18 and 23 weeks of gestational age in singleton pregnancies, and compare it to two previously published nomograms. MATERIAL AND METHODS: In this retrospective cohort study of 1107 patients, a total of 650 singleton pregnancies were included. The umbilical cord diameter measurements were performed at the level of fetal abdominal wall insertion, and were correlated with gestational age (GA) and estimated fetal weight (EFW). Statistical analysis with non-parametric polynomial least squares regression analysis was performed. RESULTS: A statistically significant correlation between umbilical cord diameter and GA (P<0001, r=0.399, 95% CI 0.331 to 0.464), and EFW (P<0001, r=0.420, 95% CI 0.353-0.483) was observed. A nomogram of umbilical cord thickness according to GA (y), and EFW (y'), was generated from the following equations:y=-51.30+5.367*x-0.1165*x(2) and y'=6.917+0.007233*x, respectively. CONCLUSION: Our nomogram is in agreement with one of the previously published nomograms that also measured umbilical cord diameter at the level of the fetal abdominal umbilical cord insertion. Therefore, we recommend umbilical cord thickness to be measured in close proximity to the fetal abdominal wall, but no further than 0.5 cm away from the wall insertion.

Body Weights and Measures↗

PubMed2004

Preoperative probability model for predicting overall survival after resection of pulmonary metastases from colorectal cancer.

BACKGROUND: The aim of this study was identify readily available factors most helpful in predicting survival and to develop a prognostic nomogram for patients with pulmonary metastases from colorectal cancer who are candidates for thoracotomy. METHODS: Pretreatment data on 313 patients with metastases who underwent thoracotomy were analysed. Fourteen preoperative clinical and pathological variables were used to develop a probability model, in which their association with 3-year survival was tested. A nomogram to predict median, 1- and 3-year survival was constructed and validated internally using the concordance index (c-index). The nomogram was then validated with an external data set. RESULTS: Five variables were identified as independent predictors of 3-year survival: prethoracotomy carcinoembryonic antigen level, number of pulmonary tumours, presence of hilar or mediastinal tumour-infiltrated lymph nodes, histology of the primary tumour and presence of extrathoracic disease. The nomogram was well calibrated for predicting 3-year overall survival. The internal validated c-index of the nomogram was 0.72. Applied to another data set, the external validated c-index was 0.66. CONCLUSION: This model has moderate predictive ability to discriminate between patients who are likely to survive after thoracotomy for pulmonary metastases from colorectal cancer.

Adult↗

PubMed2005

Integration of gene expression profiling and clinical variables to predict prostate carcinoma recurrence after radical prostatectomy.

BACKGROUND: Gene expression profiling of prostate carcinoma offers an alternative means to distinguish aggressive tumor biology and may improve the accuracy of outcome prediction for patients with prostate carcinoma treated by radical prostatectomy. METHODS: Gene expression differences between 37 recurrent and 42 nonrecurrent primary prostate tumor specimens were analyzed by oligonucleotide microarrays. Two logistic regression modeling approaches were used to predict prostate carcinoma recurrence after radical prostatectomy. One approach was based exclusively on gene expression differences between the two classes. The second approach integrated prognostic gene variables with a validated postoperative predictive model based on standard variables (nomogram). The predictive accuracy of these modeling approaches was evaluated by leave-one-out cross-validation (LOOCV) and compared with the nomogram. RESULTS: The modeling approach using gene variables alone accurately classified 59 (75%) tissue samples in LOOCV, a classification rate substantially higher than expected by chance. However, this predictive accuracy was inferior to the nomogram (concordance index, 0.75 vs. 0.84, P = 0.01). Models combining clinical and gene variables accurately classified 70 (89%) tissue samples and the predictive accuracy using this approach (concordance index, 0.89) was superior to the nomogram (P = 0.009) and models based on gene variables alone (P < 0.001). Importantly, the combined approach provided a marked improvement for patients whose nomogram-predicted likelihood of disease recurrence was in the indeterminate range (7-year disease progression-free probability, 30-70%; concordance index, 0.83 vs. 0.59, P = 0.01). CONCLUSIONS: Integration of gene expression signatures and clinical variables produced predictive models for prostate carcinoma recurrence that perform significantly better than those based on either clinical variables or gene expression information alone.

Aged↗

PubMed1978

Limitations in prediction of gestational age and birth weight by ultrasonographic methods.

The index of predictability of estimated gestational age (EGA) and birth weight (BW) from biparietal diameter (BPD) was tested in 1333 normal pregnancies; 96% of the patients were black. The correlation BPD and actual weeks to delivery was 0.834, r2 =69.5%. Confidence limits were established and a nomogram for EGA was derived. Our nomogram and two similar ones were compared. The overall correlation between them was good, but that for specific BPD and EGA was not. In addition, our BPD values were smaller for corresponding gestational ages in other nomograms. The overall accuracy of estimated delivery date was +/- 1.6 weeks. We were not able to predict birth weight at all from a single, random BPD measurement. We have demonstrated the serious limitations that exist in the prediction of gestational age from previously established nomograms. We infer that this error is even greater when homogenous populations are so studied. We suggest that any published BPD-EGA or BPD-BW nomogram be given close, intensive statistical scrutiny, within the population studied, before it is used. When such scrutiny is not possible, serial sonographic determinations, or longitudinal use of growth charts, would be more acceptable.

Adolescent↗

PubMedDate not supplied

Prenatal measurement of the fetal cerebellum and cisterna cerebellomedullaris by ultrasound.

The fetal cerebellum can be visualized with ultrasound throughout the second trimester. We describe a technique for measuring the transverse and anteroposterior cerebellar diameters and the measurement of the cisterna magna in the same plane between 14 and 32 weeks gestation. Nomograms for these measurements against gestational age showed good correlation, and narrow confidence limits for the transverse cerebellar diameter. The transverse cerebellar diameter was also measured directly in 79 fetuses after midtrimester abortion and the measurements obtained were compared with the ultrasound TCD nomogram. Good correlation, was obtained between the post mortem measurements and the ultrasound TCD nomogram. Routine use of these measurements and nomograms should prove valuable in the diagnosis of congenital abnormality of the posterior fossa and may also be of use in assessing the effect of severe intrauterine growth retardation and other insults on cerebellar growth and development. The narrow confidence limits obtained with the TCD nomogram should enable it to be used with confidence in clinical practice.

Cerebellum↗

PubMed1999

Weight-based heparin dosing is more effective in the treatment of postoperative deep vein thrombosis.

Rapid clinical diagnosis and adequate treatment are the major determinants of successful therapy of deep vein thrombosis (DVT). In the initial treatment of DVT, heparin is the anticoagulant of choice. Appropriate heparin dosing is of major interest concerning the onset of therapeutic anticoagulation and, thus, the clinical outcome of the patients. This study was designed to compare a weight-based heparin nomogram with a standard heparin nomogram for the treatment of DVT in orthopaedic patients. Forty patients in two groups were included in the study. In group one (patients treated with the weight-based heparin nomogram) the therapeutic range (partial thromboplastin time 1.5-2.3 times the control) was reached on average within 24 h (75% of the patients); 95% of the patients reached the therapeutic range within 48 h. In group two (patients treated with the standard heparin nomogram) the therapeutic range was reached on average within 48 h (60%; 30% of the patients reached the therapeutic range within 24 h). The used weight-based heparin nomogram has proved to be effective, safe and superior to one based on standard practice concerning the time elapsed between initial heparin therapy and achieving the therapeutic range for intravenous anticoagulation.

Aged↗

PubMed1989

Two-dimensional echocardiographic aortic root dimensions in normal children and adults.

Two-dimensional echocardiography is increasingly used to measure aortic root dimensions, which provide prognostic information in aortic regurgitation and the Marfan syndrome. Aortic root dilatation is currently detected by nomograms based on M-mode echocardiographic data. Aortic root diameters measured by 2-dimensional echocardiography at the anulus, sinuses of Valsalva, supra-aortic ridge and proximal ascending aorta in 135 normal adults and 52 normal children were compared with age, gender, body habitus, blood pressure and stroke volume, and with M-mode findings and normal limits. Two-dimensional measurements at the sinuses of Valsalva were larger than M-mode aortic root values (p less than 0.001), and use of 2-dimensional values with M-mode nomograms falsely diagnosed aortic dilatation in 40% of normal children and 19% of normal adults. Two-dimensional measurements at the sinuses closely correlated with body surface area in children (r = 0.93, p less than 0.0005), moderately in adults younger than 40 years of age (r = 0.71, p less than 0.0005) and weakly in older adults (r = 0.40, p less than 0.0005). In adults, gender influenced aortic root size at all levels (p less than 0.001), but dimensions were similar when indexed for body surface area. Age strongly influenced supraaortic ridge and ascending aortic diameters; blood pressure and stroke volume had no independent effect on aortic size. In conclusion, (1) 2-dimensional echocardiographic aortic root dimensions are influenced by age and body size but not by blood pressure; (2) aortic root dilatation is overdiagnosed when aortic diameter at the sinuses of Valsalva is compared with M-mode nomograms; (3) nomograms comparing aortic diameter with body surface area should be used in children; and (4) although use of nomograms based on body size in adults should maximize sensitivity for aortic dilatation, 98% specificity is attained by use of an upper normal limit of 2.1 cm/m2 for aortic diameter at the sinuses of Valsalva in both men and women.

Adolescent↗

PubMed1998

Developing and testing a system to improve the quality of heparin anticoagulation in patients with acute cardiac syndromes.

We have taken a stepwise approach to improving the dosing of continuous intravenous heparin in patients with acute coronary syndromes. Our primary objective was to use computer modeling to develop a nomogram for managing heparin therapy and to put in place a continuous quality monitoring system to evaluate the nomogram's effectiveness. We prospectively collected data on 41 patients with unstable angina or myocardial infarction who were treated with heparin. Their response to heparin was computer modeled and the dose to achieve an activated partial thromboplastin time (aPTT) ratio of 2.0 was established. This dose was regressed against all demographic characteristics to establish predictors of heparin dose (phase I). The regression formula was used prospectively in 110 patients to initiate the infusion rate of heparin and a bolus dose to achieve an aPTT ratio of 2.5. Subsequent dosage adjustments were achieved by computer modeling the patient's aPTT response (phase II). A nomogram was developed that simulated the decisions achieved using computer-assisted methods. This was retrospectively tested and then prospectively tested in 50 patients using nursing staff (phase IV). The nomogram was then made generally available (phase IV) and has been tested in an additional 310 patients. Phase I: Of the original 41 patients, 32% of the aPTT ratios were in the therapeutic range, 36% were supratherapeutic, and 32% were subtherapeutic after the first 24 hours. Phases II and III resulted in 85% of the aPTT ratios between 1.5 and 2.5 at 24 hours. Phase 4 had similar results in 310 patients. The use of computer-assisted or a computer-generated nomogram to adjust heparin therapy results in better control of heparin therapy than using standard methods.

Adult↗

PubMed2002

Conductive keratoplasty for the correction of low to moderate hyperopia: 1-year results on the first 54 eyes.

OBJECTIVE: To document the 1-year postoperative clinical results of the safety, efficacy, and stability of conductive keratoplasty (CK) to correct low to moderate hyperopia. DESIGN: Prospective, nonrandomized, self-controlled trial. PARTICIPANTS: Five surgeons at four centers performed CK on the first 54 eyes of a multicenter, 2-year clinical trial. Treated eyes had +0.875 to +4.00 diopters (D) of hyperopia and < or =0.75 D of cylinder. The nature of this procedure was explained to all participating patients who signed informed consent forms prior to undergoing the procedure. INTERVENTION: Low energy, high-frequency current was applied directly into the peripheral corneal stroma through a delivery tip inserted at 16 or more treatment spots. An early nomogram was used for the first 54 eyes with an intended refraction of plano. MAIN OUTCOME MEASURES: Data from all 54 eyes were analyzed for safety and stability. A subset of 30 of the 54 eyes was found that had been treated with the appropriate number of spots with the early nomogram. These eyes were categorized as current nomogram eyes; the data for these eyes were analyzed for efficacy and predictability, as well as stability and safety. All patients reported on satisfaction and quality of vision after surgery. RESULTS: Preoperatively, the manifest refractive spherical equivalent refraction (MRSE) of the 30 current nomogram eyes was +1.57 D. At 1 year postoperatively, uncorrected visual acuity was 20/20 or better in 57% of the eyes and 20/40 or better in 93%. The MRSE was within 0.50 D in 46%, within +/-1.00 D in 93%, and within +/-2.00 D in 100%. No eye lost > or =2 lines of best spectacle-corrected visual acuity at 1 year postoperatively nor had an induced cylinder of > or =2.00 D. The MRSE changed a mean of 0.25 D +/- 0.43 between 3 and 6 postoperative months, 0.16 D +/- 0.38 between 6 and 9 postoperative months, and 0.07 D +/- 0.38 between 9 and 12 postoperative months. Refractive stability appeared to be attained by 6 months postoperatively. CONCLUSIONS: Conductive keratoplasty appears to be safe, effective, and stable for correcting low to moderate spherical hyperopia. Stability appeared by the 6-month follow-up visit. For the eyes treated with the current CK nomogram, uncorrected visual acuity, predictability, and stability are as good as or better than those obtained with hyperopic laser in situ keratomileusis or noncontact laser thermal keratoplasty.

Adult↗

PubMed1996

Transverse incisions for mixed and myopic idiopathic astigmatism.

PURPOSE: To determine the efficacy and safety of the Casebeer transverse nomogram for correcting idiopathic astigmatism using transverse incisions (T-incisions) with variable optical zones. SETTING: Rancho Bernardo Eye Center, San Diego, California. METHODS: This retrospective study comprised 173 eyes of 100 consecutive patients who had T-incisions according to the Casebeer transverse nomogram to correct mixed or myopic astigmatism. Preoperative cylinder ranged from 0.75 to 6.00 diopters (D). The nomogram was modified for eyes with preoperative cylinder from 1.75 to 6.00 D. Principal outcome measures were net residual astigmatism for all eyes and uncorrected visual acuity in eyes with the highest preoperative cylinder (3.25 to 6.00 D). RESULTS: A comparison of preoperative astigmatism (mean 3.07 D +/- 1.53 [SD]) and net residual astigmatism showed significant reduction in all diopter categories. Enhancements were done in 16.2% of eyes, mostly those with high preoperative cylinder. Patient age did not seem to affect results. No patient, including those with smaller optical zones, lost two or more Snellen lines of best corrected visual acuity. CONCLUSION: Use of the Casebeer transverse nomogram with T-incisions and variable optical zones effectively and safely reduced most idiopathic astigmatism between 0.75 and 5.50 D. Modifications to the nomogram yielded similar results in eyes with a higher preoperative cylinder.

Adult↗