American College of Cardiology/American Heart Association preoperative assessment guidelines reduce resource utilization before aortic surgery

BACKGROUND: Methods used for evaluation of cardiac risk before noncardiac surgery vary widely. We evaluated the effect over time on practice and resource utilization of implementing the American College of Cardiology/American Heart Association Guidelines on Preoperative Risk Assessment. METHODS: We compared 102 historical control patients who underwent elective abdominal aortic surgery (from January 1993 to December 1994) with 94 consecutive patients after guideline implementation (from July 1995 to December 1996) and 104 patients in a late after guideline implementation (from July 1, 1997, to September 30, 1998). Resource use (testing, revascularization, and costs) and outcomes (perioperative death and myocardial infarction) were examined. Patients with and without clinical markers of risk for perioperative cardiac complications were compared. RESULTS: The use of preoperative stress testing (88% to 47%; P <.00001), cardiac catheterization (24% to 11%; P <.05), and coronary revascularization (25% to 2%; P <.00001) decreased between control and postguideline groups, respectively. These changes persisted in the late postguideline group. Mean preoperative evaluation costs also fell ($1087 versus $171; P <.0001). Outcomes of death (4% versus 3% versus 2%) and myocardial infarction (7% versus 3% versus 5%) were not significantly different between control, postguideline, and late postguideline groups, respectively. Stress test rates were similar for patients at low risk versus high risk in the historical control group (84% versus 91%; P =.29) but lower for patients at low risk after guideline implementation (31% versus 61%; P =.003). CONCLUSION: Implementation of the American College of Cardiology/American Heart Association cardiac risk assessment guidelines appropriately reduced resource use and costs in patients who underwent elective aortic surgery without affecting outcomes. This effect was sustained 2 years after guideline implementation.     

Development of efficient threshold strategies for frequency doubling technology perimetry using computer simulation

PURPOSE: To develop new test procedures for frequency-doubling technology (FDT) perimetry that improve performance beyond those currently used. METHODS: Two novel threshold estimation procedures were evaluated: a rapid, efficient binary search technique (REBS) and a maximum-likelihood estimation (ZEST) procedure. A computerized visual field simulation model was developed to determine the accuracy and efficiency of these procedures. This model was constructed using previously derived characteristics of FDT perimetry from both normal observers (n = 506) and those with glaucomatous visual field loss (n = 352). The computer simulation program was used to determine the best parameters for the two new procedures and the effect of variability and response errors on algorithm performance. Comparisons were made to the performance of the modified binary search (MOBS) procedure used in the current commercial implementation of the FDT perimeter. RESULTS: Both the optimized REBS and ZEST procedures approximately halved the time required for FDT threshold testing without loss of accuracy or reproducibility. CONCLUSIONS: With suitable parameter choices, comparable performance was achieved using either ZEST or REBS. Simulation results indicate that accurate thresholds can be measured with an optimized ZEST or REBS procedure in approximately half the time required by traditional estimation methods.     

Progression of visual field loss in untreated glaucoma patients and glaucoma suspects in St. Lucia,West Indies

PURPOSE: A 1986-1987 survey found 8.8% prevalence of open-angle glaucoma in the black population of St. Lucia, West Indies. This follow-up study assessed visual field loss progression in untreated glaucoma patients and glaucoma suspects 10 years later. DESIGN: Cohort study. METHODS: Subjects were 205 glaucoma patients and suspects; 1987 data included age, sex, visual acuity, and visual fields measured by automated threshold perimetry (Humphrey C 30-2 test), and 1997 data included intraocular pressure, visual acuity, and visual fields measured by the same test. Exclusion criteria included field unreliability, field improvement due to vision improvement, nonglaucomatous vision deterioration, glaucoma treatment since 1988, and scoring of a visual field as end stage in 1987. Visual fields were scored by algorithms for the Advanced Glaucoma Intervention Study (AGIS) and Collaborative Initial Glaucoma Treatment Study (CIGTS). RESULTS: By AGIS criteria, 55% of 146 right eyes and 52% of 141 left eyes showed progression of visual field loss. In linear regressions, progression severity was unassociated with sex, intraocular pressure, or baseline visual field score, but was positively associated with age (P <.001, right; P =.002, left). The cumulative probability of reaching end stage in 10 years in at least one eye was approximately 16% by AGIS criteria. By CIGTS criteria, 73% of 146 right eyes and 72% of 141 left eyes progressed. CONCLUSIONS: These data provide a unique opportunity to study progression of untreated glaucoma. The percentage of eyes showing visual field loss progression and the percentage reaching end stage were considerably higher than in studies of visual field progression in treated eyes.     

Laser epithelial keratomileusis for myopia with the autonomous laser

PURPOSE: To describe the refractive outcome, objective clinical data, and subjective patient experiences after laser epithelial keratomileusis (LASEK) at 1, 3, and 6 months after surgery. METHODS: This was a retrospective, nonrandomized, comparative study of 58 LASEK-treated eyes (36 patients) with myopia (with and without astigmatism) between -1.50 and -14.75 D (mean -7.80 +/- 2.90 D, median -7.90 D). Refractive surgery was performed using the Alcon Summit Autonomous LADAR Vision excimer laser. Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, stability of refraction, and corneal haze were evaluated before surgery and up to 6 months after surgery. A group of randomly selected LASIK-treated eyes were compared at each time point. RESULTS: Patients who opted for monovision (n=12) were excluded. In the emmetropia targeted eyes (n=46), 45%, 83%, 85%, and 89% achieved 20/40 or better uncorrected Snellen visual acuity (UCVA) at 1 day, 1 week, 2 weeks, and 1 month respectively. At 6 months, 73% (n=28) of eyes treated achieved UCVA 20/20 with 97% achieving 20/40 or better (mean, -0.51 D). At 3 and 6 months, 71% (n=46) and 68% (n=28) were within +/- 0.50 D of emmetropia. The percentage of eyes that achieved UCVA 20/40 or better at 6 months was 97% (n=28). Visually significant corneal haze was evident in two LASEK-treated patients (four eyes) at 6 months. No eyes lost two or more lines of best spectacle-corrected Snellen visual acuity. CONCLUSIONS: Preliminary data suggest that LASEK appears to be a safe, effective, and comparable alternative to LASIK, even for higher amounts of myopia. A prospective, randomized clinical trial is needed to better define the role of LASEK as it compares to other refractive procedures, specifically LASIK and PRK.     

Using machine learning classifiers to identify glaucomatous change earlier in standard visual fields

PURPOSE: To compare the ability of several machine learning classifiers to predict development of abnormal fields at follow-up in ocular hypertensive (OHT) eyes that had normal visual fields in baseline examination. METHODS: The visual fields of 114 eyes of 114 patients with OHT with four or more visual field tests with standard automated perimetry over three or more years and for whom stereophotographs were available were assessed. The mean (+/-SD) number of visual field tests was 7.89 +/- 3.04. The mean number of years covered (+/-SD) was 5.92 +/- 2.34 (range, 2.81-11.77). Fields were classified as normal or abnormal based on Statpac-like methods (Humphrey Instruments, Dublin, CA) and by several machine learning classifiers. The machine learning classifiers were two types of support vector machine (SVM), a mixture of Gaussian (MoG) classifier, a constrained MoG, and a mixture of generalized Gaussian (MGG). Specificity was set to 96% for all classifiers, using data from 94 normal eyes evaluated longitudinally. Specificity cutoffs required confirmation of abnormality. RESULTS: Thirty-two percent (36/114) of the eyes converted to abnormal fields during follow-up based on the Statpac-like methods. All 36 were identified by at least one machine classifier. In nearly all cases, the machine learning classifiers predicted the confirmed abnormality, on average, 3.92 +/- 0.55 years earlier than traditional Statpac-like methods. CONCLUSIONS: Machine learning classifiers can learn complex patterns and trends in data and adapt to create a decision surface without the constraints imposed by statistical classifiers. This adaptation allowed the machine learning classifiers to identify abnormality in visual field converts much earlier than the traditional methods.     

Effect of doxazosin on arterial elasticity: functional versus structural changes

Drugs and diseases have differential effects on functional and structural components of large-conduit arteries and smaller vessels. The objective of this study was to demonstrate functional and structural effects of doxazosin (DOX) on largevessel and small-vessel arterial elasticity in hypertension (HTN). This was an open-label, single-blind, active-therapy study. Patients with stage 1 to 2 HTN were administered DOX 2 mg/day for 3 months and 4 mg/day for 1 month, if indicated, followed by 2-week washout period. Arterial elasticity was measured noninvasively at baseline, at 3 months and 4 months of treatment, and 2 weeks following DOX withdrawal. Although the observed effects were not statistically significant, large-vessel elasticity (C1) increased in a dose-related manner and returned to baseline 2 weeks after drug withdrawal. There was a trend toward an increase in small-vessel elasticity in a dose-related manner. However, 2 weeks after drug withdrawal, C2 (distal elasticity) had not returned to baseline and was statistically significantly different from baseline (p = 0.032). It was concluded that large-artery compliance increased in a dose-related manner. Almost all benefit was lost within 2 weeks of discontinuation, suggesting the DOX effect was functional. Small-artery compliance improved in a dose-related manner but only partially returned to baseline after DOX withdrawal, suggesting changes in artery structure by DOX.     

Nurse training. Teenage hang-ups

A survey of acute trusts' nurse cadet schemes in England showed a wide variety in entry requirements and qualifications offered. Most schemes offered successful students a place on a nurse training scheme. Legal issues surrounding 16-year-olds working in hospitals need to be clarified. Standardisation of entry requirements and course qualifications is required. At present, a student could complete a cadet course in one part of the country and not be eligible for nurse training elsewhere.