The safety of carotid endarterectomy in patients with preoperative renal dysfunction

Recent published data suggest that performing carotid endarterectomy (CEA) in patients with renal dysfunction is associated with a prohibitively high perioperative stroke and death rate. On the basis of our experience, we hypothesized that CEA is a safe procedure in patients with renal insufficiency. A retrospective review of one surgeon's CEA experience from 1988 to 1998 was performed. A total of 398 procedures performed on 370 patients were reviewed for patient demographics and adverse events in the 30-day perioperative period. Risk factors, indications for procedure, and degree of stenosis, as well as intraoperative use of shunts, patch angioplasty, drains, completion angiography, and EEG monitoring were compared. Patients were categorized by preoperative creatinine (Cr) levels as normal (Cr <or= 1.5) or abnormal (Cr > 1.5). All data were subjected to statistical analysis. Our results showed that CEA can be performed safely in patients with renal dysfunction with no increase in perioperative stroke or death rate. Performing CEA in patients with renal insufficiency does require preoperative cardiac evaluation and close cardiac monitoring, as there appears to be an increased rate of myocardial infarction in our series.

Probability binning comparison: a metric for quantitating univariate distribution differences

BACKGROUND

Comparing distributions of data is an important goal in many applications. For example, determining whether two samples (e.g., a control and test sample) are statistically significantly different is useful to detect a response, or to provide feedback regarding instrument stability by detecting when collected data varies significantly over time.

METHODS

We apply a variant of the chi-squared statistic to comparing univariate distributions. In this variant, a control distribution is divided such that an equal number of events fall into each of the divisions, or bins. This approach is thereby a mini-max algorithm, in that it minimizes the maximum expected variance for the control distribution. The control-derived bins are then applied to test sample distributions, and a normalized chi-squared value is computed. We term this algorithm Probability Binning.

RESULTS

Using a Monte-Carlo simulation, we determined the distribution of chi-squared values obtained by comparing sets of events derived from the same distribution. Based on this distribution, we derive a conversion of any given chi-squared value into a metric that is analogous to a t-score, i.e., it can be used to estimate the probability that a test distribution is different from a control distribution. We demonstrate that this metric scales with the difference between two distributions, and can be used to rank samples according to similarity to a control. Finally, we demonstrate the applicability of this metric to ranking immunophenotyping distributions to suggest that it indeed can be used to objectively determine the relative distance of distributions compared to a single control.

CONCLUSION

Probability Binning, as shown here, provides a useful metric for determining the probability that two or more flow cytometric data distributions are different. This metric can also be used to rank distributions to identify which are most similar or dissimilar. In addition, the algorithm can be used to quantitate contamination of even highly-overlapping populations. Finally, as demonstrated in an accompanying paper, Probability Binning can be used to gate on events that represent significantly different subsets from a control sample. Published 2001 Wiley-Liss, Inc.

Probability binning comparison: a metric for quantitating multivariate distribution differences

BACKGROUND

While several algorithms for the comparison of univariate distributions arising from flow cytometric analyses have been developed and studied for many years, algorithms for comparing multivariate distributions remain elusive. Such algorithms could be useful for comparing differences between samples based on several independent measurements, rather than differences based on any single measurement. It is conceivable that distributions could be completely distinct in multivariate space, but unresolvable in any combination of univariate histograms. Multivariate comparisons could also be useful for providing feedback about instrument stability, when only subtle changes in measurements are occurring.

METHODS

We apply a variant of Probability Binning, described in the accompanying article, to multidimensional data. In this approach, hyper-rectangles of n dimensions (where n is the number of measurements being compared) comprise the bins used for the chi-squared statistic. These hyper-dimensional bins are constructed such that the control sample has the same number of events in each bin; the bins are then applied to the test samples for chi-squared calculations.

RESULTS

Using a Monte-Carlo simulation, we determined the distribution of chi-squared values obtained by comparing sets of events from the same distribution; this distribution of chi-squared values was identical as for the univariate algorithm. Hence, the same formulae can be used to construct a metric, analogous to a t-score, that estimates the probability with which distributions are distinct. As for univariate comparisons, this metric scales with the difference between two distributions, and can be used to rank samples according to similarity to a control. We apply the algorithm to multivariate immunophenotyping data, and demonstrate that it can be used to discriminate distinct samples and to rank samples according to a biologically-meaningful difference.

CONCLUSION

Probability binning, as shown here, provides a useful metric for determining the probability with which two or more multivariate distributions represent distinct sets of data. The metric can be used to identify the similarity or dissimilarity of samples. Finally, as demonstrated in the accompanying paper, the algorithm can be used to gate on events in one sample that are different from a control sample, even if those events cannot be distinguished on the basis of any combination of univariate or bivariate displays. Published 2001 Wiley-Liss, Inc.

Issues confronting lesbian and gay elders: the challenge for health and human services providers

During the past two decades, the number of people over the age of 65 in the United States has been increasing twice as fast as the rest of the population. Within this diverse group, gerontologists are increasingly aware that there also exists a large population of older lesbian, gay men, and bisexuals. Health professionals must learn to acknowledge and meet the needs of this population. This article assists in addressing the knowledge gap by acquainting the reader with the aging concerns of lesbian and gay men; the impact of homophobia on their health; common heterosexual practices and their impact on care; retirement and leisure issues; the hidden incidence of abuse and neglect; and some suggested strategies that will assist health and human services workers in providing quality care for lesbians and gays as they age.

HPV DNA testing of the residual sample of liquid-based Pap test: utility as a quality assurance monitor

HPV DNA testing of the residual sample volume of liquid-based Pap tests has been recommended as a way to determine the appropriate follow-up for women who have equivocal results in routine clinical screening. A major aspect of quality assurance in the cytopathology laboratory consists of correlation of smear interpretation with biopsy or conization results as mandated by CLIA '88. However, the use of histology as the gold standard suffers from similar problems of subjectivity and sampling as the Pap smear. In this study we explore the potential use of HPV DNA testing of the residual volume from the ThinPrep Pap Test (Cytyc Corporation, Boxborough, Massachusetts) as a substitute gold standard in quality assurance monitoring of a cervical cytology screening program. The residual samples from 397 ThinPrep Pap cases were retrospectively analyzed for high-risk HPV DNA using the Hybrid Capture II technique. Sensitivity (71.8%), specificity (86.5%), predictive value of positive (77.1%) and negative (82.9%) ThinPrep Pap interpretations were calculated on the basis of HPV DNA results for 266 cases classed as either squamous intraepithelial lesion (SIL) or negative. Overall, there was agreement between the two tests in 80.8% of cases (Cohen's kappa =.59). The percentage of HPV DNA-positive cases interpreted as atypical squamous cells of uncertain significance (ASCUS) was 43.7%, and the percentage of negative cases was 17.1%. We believe that this approach is an objective adjunct to the traditional quality assurance protocol, with the added benefit that it includes cases interpreted as negative, as well as abnormal cases that do not come to biopsy.

Timing for repeated treatment of hyperthyroid disease with radioactive iodine after initial treatment failure

PURPOSE

It has been reported that the effect of radioactive iodine (RAI) treatment is complete in 4 to 6 months. This retrospective study evaluated the appropriate time for repeated treatment of hyperthyroid disease with RAI after initial treatment failure.

METHODS

Outcomes of 128 patients treated with RAI for hyperthyroid disease were reviewed retrospectively at 3 and 6 months.

RESULTS

Eighty patients (group A) were treated successfully with a single dose of RAI. Twenty patients (group B) required a second treatment dose. Twenty-eight patients were lost to follow-up. All patients in group A were clinically improved to various degrees at 3 months and continued to improve at 6 months. All eight patients in group B who showed no improvement at 3 months remained the same at 6 months. The difference between the two groups was statistically significant.

CONCLUSION

Patients with hyperthyroid disease who are unimproved at 3 months can be retreated with RAI without further delay.

Carotid endarterectomy without pre-operative angiography

Carotid endarterectomy is being performed with increasing frequency without the benefit of preoperative angiography, based purely on duplex scanning. The available data attest to its safety, with the caveats that the duplex scan is unimpeachable, and that the symptoms and duplex scan findings are consistent. Given the well documented risk of stoke as a consequence of cerebral angiography being at least 1%, the elimination of this risk by the omission of contrast angiography would reduce the neurological morbidity and mortality rate of the diagnosis and treatment of carotid bifurcation disease by approximately 50%. The available data make a compelling case for carotid endarterectomy based on duplex scanning, without preoperative angiography, as the preferred approach to treatment of carotid artery stenosis.

Outcomes of a brief inpatient treatment program for mood and anxiety disorders

Findings are reported from a study on outcomes of a brief psychiatric inpatient treatment program (7-day average) for 67 patients with mood and anxiety disorders. Multiple outcomes measures were completed by patients, family members, and clinicians at admission, discharge, and 3 months after discharge. Findings included significant improvement from admission to discharge, with maintenance of gains 3 months later and few readmissions. Implications for psychiatric nursing practice in today's health care environment are discussed.

Mutation detection in the breast cancer gene BRCA1 using the protein truncation test

About 400 distinct mutations have been defined in the BRCA1 gene, and these are spread fairly evenly through the 5592 bp of coding DNA. This circumstance presents a formidable challenge for mutation screening. Apart from total direct sequencing, the preferred screening method has been single-strand conformation polymorphism (SSCP) gels, with a smaller input from constant denaturant gradient electrophoresis (CDGE), heteroduplex (HD) analysis, and mismatch cleavage. The protein truncation test (PTT) was used early in BRCA1 mutation screening but has not been widely adopted, perhaps because a straightforward analysis of the whole BRCA1 gene requires working with RNA and all its perceived problems. The present work was undertaken to assess the practicality of using the PTT under routine conditions for the screening of long genes such as BRCA1 that are not highly expressed in lymphocytes. We conclude that, provided RNA preparation is carried out effectively and consistently, the PTT approach has significant advantages over other methodologies such as SSCP gels.

Underperforming doctors. Back from the brink

The UK has a poor record on retraining underperforming doctors and rehabilitating sick ones. But that is set to change. Wendy Moore examines new attitudes and plans of action aimed at meeting the demands of the clinical governance revolution.

The role of patch angioplasty in prevention of early recurrent carotid stenosis

The aim of this study was to determine the effect of primary closure versus patch angioplasty on the incidence of early recurrent stenosis after carotid endarterectomy in the hands of a single surgeon, and to analyze the risk factors associated with early recurrent stenosis after carotid endarterectomy. A retrospective review was performed of 178 consecutive patients who underwent 200 carotid endarterectomies-100 done consecutively with primary closure and 100 done consecutively with patch angioplasty. Of these patients, 126 qualified for analysis by having had at least 18 months of follow-up by serial duplex scanning. Of this group, the first 65 patients underwent 75 routine primary closures, while the last 61 underwent 67 routine patch angioplasties. All patients underwent a completion angiogram at the end of the case. Recurrent stenosis was defined as luminal diameter narrowing >60% on duplex scan. A multifactorial analysis was performed to analyze the effect of age, sex, tobacco use, diabetes, hypertension, peripheral vascular disease, coronary artery disease, and contralateral stenosis on recurrent stenosis. The results of this study showed that in a single surgeon's experience with carotid endarterectomy, varying only the method of closure between primary closure versus patch angioplasty, there is no statistically significant difference in the rate of early restenosis. No difference was noted in the perioperative morbidity and mortality between groups.

Renal assessment practices and the effect of nurse case management of health maintenance organization patients with diabetes

OBJECTIVE

To examine baseline renal screening practices and the effect of nurse case management of patients with diabetes in a group model health maintenance organization (HMO).

RESEARCH DESIGN AND METHODS

We performed both 1-year retrospective and 1-year prospective studies of renal assessment practices and ACE inhibitor usage in a cohort of 133 diabetic patients enrolled in a randomized controlled trial of a diabetes nurse case management program in a group model HMO. In accordance with American Diabetes Association recommendations, urine dipstick and quantitative protein and microalbuminuria testing rates were calculated.

RESULTS

At baseline, 77% of patients were screened for proteinuria with dipsticks or had quantitative urine testing. Of patients with negative dipstick findings, 30% had appropriate quantitative protein or microalbumin follow-up at baseline. Baseline ACE inhibitor usage was associated with decreased follow-up testing (relative risk = 0.47). Nurse case management was associated with increased quantitative protein or or microalbumin testing and increased follow-up testing (relative risk = 1.65 and 1.60, respectively).

CONCLUSIONS

We found a higher degree of adherence to recommendations for renal testing than has been reported previously. Nurse case management intervention further increased renal screening rates. The inverse association between ACE inhibitor usage and microalbumin testing highlights a potentially ambiguous area of current clinical pathways.

Nurse case management to improve glycemic control in diabetic patients in a health maintenance organization. A randomized, controlled trial

BACKGROUND

Control of hyperglycemia delays or prevents complications of diabetes, but many persons with diabetes do not achieve optimal control.

OBJECTIVE

To compare diabetes control in patients receiving nurse case management and patients receiving usual care.

DESIGN

Randomized, controlled trial.

SETTING

Primary care clinics in a group-model health maintenance organization (HMO).

PATIENTS

17 patients with type 1 diabetes mellitus and 121 patients with type 2 diabetes mellitus.

INTERVENTION

The nurse case manager followed written management algorithms under the direction of a family physician and an endocrinologist. Changes in therapy were communicated to primary care physicians. All patients received ongoing care through their primary care physicians.

MEASUREMENTS

The primary outcome, hemoglobin A1c (HbA1c) value, was measured at baseline and at 12 months. Fasting blood glucose levels, medication type and dose, body weight, blood pressure, lipid levels, patient-perceived health status, episodes of severe hypoglycemia, and emergency department and hospital admissions were also assessed.

RESULTS

72% of patients completed follow-up. Patients in the nurse case management group had mean decreases of 1.7 percentage points in HbA1c values and 43 mg/dL (2.38 mmol/L) in fasting glucose levels; patients in the usual care group had decreases of 0.6 percentage points in HbA1c values and 15 mg/dL (0.83 mmol/L) in fasting glucose levels (P < 0.01). Self-reported health status improved in the nurse case management group (P = 0.02). The nurse case management intervention was not associated with statistically significant changes in medication type or dose, body weight, blood pressure, or lipids or with adverse events.

CONCLUSIONS

A nurse case manager with considerable management responsibility can, in association with primary care physicians and an endocrinologist, help improve glycemic control in diabetic patients in a group-model HMO.

EMS-initiated refusal and alternative methods of transport

OBJECTIVES

1) To describe characteristics of patient transport protocols in those U.S. cities that sanction EMS-initiated refusal of transport; and 2) to describe the frequency and type of alternatives to emergency ambulance transport.

METHODS

EMS systems in every one of the 200 largest cities in the United States were surveyed by telephone regarding EMS-initiated refusal policies, involvement of physicians in the decision-making process, and the presence or absence of alternatives to EMS transport.

RESULTS

100% of the target population responded to the telephone survey. Only 34 (17%) EMS systems have written protocols that allow EMS providers to refuse emergency ambulance transport for patients judged to have minor illness or injury after examination. Twenty-one (62%) of these EMS systems do not require on-line physician approval for EMS-initiated refusals. Seven (21%) EMS systems that allow refusal of transport also have a formalized alternative transport program in place. Nationwide, only 19 (10%) cities surveyed offer some type of alternative to ambulance transport, most commonly taxi and minivan.

CONCLUSION

The authors report the first national survey of EMS-initiated refusal practices. Few urban EMS systems have implemented this policy to decrease utilization by persons with low-acuity illness or injury. This may be related to the fact that few EMS systems currently have alternatives to emergency ambulance transport.

Termination of nontraumatic cardiac arrest resuscitative efforts in the field: a national survey

OBJECTIVES

1) To describe elements of adult nontraumatic cardiac arrest protocols in those U.S. cities in which resuscitative efforts are being terminated in the out-of-hospital setting. 2) To determine the prevalence and methods of on-scene family grief counseling delivered in this setting.

METHODS

Emergency medical services (EMS) systems in each of the 200 largest cities in the United States were surveyed by telephone regarding the content of their adult cardiac arrest protocols. Type of arrest (medical vs trauma), final dysrhythmia, termination policies, and presence or absence of a grief counseling protocol were recorded.

RESULTS

All of the target population responded to the telephone survey. Most (135; 68%) EMS systems currently have written protocols that allow in-field termination of resuscitative efforts for adult nontraumatic cardiac arrest patients who remain asystolic. Only 47 (24%) EMS systems allow cessation of efforts for patients without return of spontaneous circulation regardless of the dysrhythmia. Base station contact is required for authorization to end resuscitative efforts in 120/135 (89%) EMS systems. Only 26/135 (19%) EMS systems that cease efforts in the field have written policies concerning on-scene family grief counseling. This counseling is most likely to be conducted by the out-of-hospital providers themselves.

CONCLUSION

Many U.S. urban EMS systems are terminating efforts for selected adult nontraumatic cardiac arrest patients, although few have written policies to address grief intervention for family members at the scene.

Cigarette smoking increases endothelial-derived vasorelaxation in the rat carotid artery in a dose-dependent manner

While there is clear-cut epidemiologic, morphologic, and functional evidence to suggest that cigarette smoking is deleterious to the cardiovascular system and endothelium, previous experiments with regard to the effect of cigarette smoking on endothelial-derived vasorelaxation are not conclusive. This study examines the effect of cigarette smoking on endothelium-derived vasorelaxation and its relationship to serum nitric oxide concentrations. Fourteen Sprague-Dawley rats (350-500 g) were divided into two groups (N = 7). The experimental group was exposed to six cigarettes (Kentucky 1R4F) per day for 50 days using a Griffith snout exposure method. The two groups were sacrificed and the carotid arteries were mounted on isometric force transducers in a physiologic bath. The arteries were constricted with norepinephrine (1 x 10(-4) M). Vasorelaxation to acetylcholine (Ach) was measured in a dose response manner. Vasorelaxation to nitroglycerin was measured at 10(-4) M. After the rats were sacrificed, blood samples from each rat were examined for total nitrate/nitrite concentration with serum chemiluminescence on a vanadium column. The results were analyzed with ANOVA and the Student's t test. Vasorelaxation to nitroglycerin was 17.42% +/- 0. 44 versus 16.25% +/- 0.42 in the control and smoke exposure groups, respectively (P = 0.19). This experiment counterintuitively demonstrates that cigarette smoking augments endothelial-derived vasorelaxation. No effect was noted in the endothelium-independent vasorelaxation to nitroglycerin. Alternative mechanisms including the presence of hypoxia and exogenous nitric oxide, which lead to endothelial-dependent and -independent vasorelaxation secondary to cigarette smoking, may serve to explain the apparent augmentation of endothelial-derived vasorelaxation. Further experiments with isolated components of smoke will need to be done to resolve the debate.

Medical education. Speak to me before it's too late

Doctors' failure to communicate with patients is at the root of many complaints. But an increasing number of medical schools are now teaching their students how to talk to patients. Wendy Moore reports.

The genetic and bacteriological aspects of Peyronie's disease

PURPOSE

Peyronie's disease has been associated with HLA tissue types, including HLA-A1, DR3, DQw2 and HLA-B7 cross-reactive group antigens which include HLA-B27. This association was tested as was the process of molecular mimicry where the host HLA surface antigen cross-reacts with a microorganism.

MATERIALS AND METHODS

HLA tissue typing was performed on 51 white patients with Peyronie's disease, of whom 15 also had Dupuytren's contracture of the hand. Fecal, urine and urethral samples were taken from patients with Peyronie's disease who had proved penile inflammation on biopsy. The samples were cultured for species of Campylobacter, Shigella, Salmonella, Yersinia, Chlamydia and gonococcus, all known to cross-react with the HLA-B27 surface antigen. Antibodies to Klebsiella species, Proteus species and Escherichia coli were also assessed in the sera of 65 patients with Peyronie's disease.

RESULTS

A significant association between Peyronie's disease and HLA-B27 was found (p = 0.02). The remaining antigens of the HLA-B7 group were not significantly associated with the disease individually (HLA-B7 p > 0.2, HLA-B22 p > 0.6, HLA-B40 p > 0.7) or as a group (p = 0.69). The previously found associations did not reach significance in this study (HLA-A1 p > 0.5, HLA-B8 p > 0.2, HLA-Cw7 p = 0.1, HLA-DR3 p > 0.4, HLA-DQ2 p > 0.4). Cultures for all enteric and urethral organisms were negative, and patients with Peyronie's disease did not have elevated serum titers of anti Klebsiella, anti Proteus or anti E. coli antibodies.

CONCLUSIONS

Although there is an association between Peyronie's disease and HLA-B27, molecular mimicry does not occur with the organisms tested, and an infectious agent has not been found in this study.

Validation of a knowledge-based boundary detection algorithm: a multicenter study

A completely operator-independent boundary detection algorithm for multigated blood pool (MGBP) studies has been evaluated at four medical centers. The knowledge-based boundary detector (KBBD) algorithm is nondeterministic, utilizing a priori domain knowledge in the form of rule sets for the localization of cardiac chambers and image features, providing a case-by-case method for the identification and boundary definition of the left ventricle (LV). The nondeterministic algorithm employs multiple processing pathways, where KBBD rules have been designed for conventional (CONV) imaging geometries (nominal 45 degrees LAO, nonzoom) as well as for highly zoomed and/or caudally tilted (ZOOM) studies. The resultant ejection fractions (LVEF) from the KBBD program have been compared with the standard LVEF calculations in 253 total cases in four institutions, 157 utilizing CONV geometry and 96 utilizing ZOOM geometries. The criteria for success was a KBBD boundary adequately defined over the LV as judged by an experienced observer, and the correlation of KBBD LVEFs to the standard calculation of LVEFs for the institution. The overall success rate for all institutions combined was 99.2%, with an overall correlation coefficient of r=0.95 (P<0.001). The individual success rates and EF correlations (r), for CONV and ZOOM geometers were: 98%, r=0.93 (CONV) and 100%, r=0.95 (ZOOM). The KBBD algorithm can be adapted to varying clinical situations, employing automatic processing using artificial intelligence, with performance close to that of a human operator.

Induction of vascular permeability enhancement by human tryptase: dependence on activation of prekallikrein and direct release of bradykinin from kininogens

Tryptase is a trypsin-type serine protease that is released from mast cells. Bradykinin (BK) is released directly from kininogens or through activation of either Hageman factor or subsequent plasma prekallikrein. Its nasal administration or inhalation induces allergy-like symptoms. Although elevated levels of tryptase and BK in allergic fluids have been detected, the role of this proteinase and the mechanism of BK production at allergic reaction sites are still unknown. To investigate the pathologic functions of tryptase, the enzyme, purified from human lung, was incubated with normal human plasma, deficient plasmas, kininogens, or prekallikrein. High molecular weight kininogen was then added, and the mixtures were examined for vascular permeability enhancement (VPE) activity, a representative function of bradykinin, using guinea pig skin. Tryptase-treated plasma induced VPE in a dose-dependent manner; activity was lost in the absence of a kininase inhibitor but not an antihistamine drug. Tryptase produced VPE activity from normal or Hageman factor-deficient plasma, but only 30% of this activity was produced from prekallikrein-deficient plasma. Significantly, no activity was obtained from kininogen-deficient plasma. Deficient plasma that were reconstituted with each missing factor resulted in VPE-inducing capacity by tryptase, equivalent to that found with normal plasma. Incubation of tryptase with high or low molecular weight kininogen induced VPE activity in a dose- and incubation time-dependent manner. Prekallikrein incubated with tryptase also generated a soybean trypsin inhibitor-sensitive VPE-inducing activity from high molecular weight kininogen. The loss of tryptase VPE-producing activity as a function of incubation time was found to be a result of spontaneous inactivation of the enzyme and not of the degradation of high molecular weight kininogen by the enzyme. We conclude that tryptase induces VPE by releasing BK, primarily through prekallikrein activation, but also through direct release from kininogens. This indicates that this mast cell-derived proteinase contributes to kinin production in allergic diseases.