Semiclassical inverse spectral problem for seismic surface waves in isotropic media: part I. Love waves (original) (raw)

The effect of surgeon's specialty and volume on the perioperative outcome of carotid endarterectomy

Journal of Vascular Surgery, 2013

Background: Several studies have demonstrated better outcomes for carotid endarterectomy (CEA) at high-volume hospitals and providers. However, only a few studies have reported on the impact of surgeons' specialty and volume on the perioperative outcome of CEA. Methods: This is a retrospective analysis of CEA during a recent 2-year period. Surgeons' specialties were classified according to their Board specialties into general surgeons (GS), cardiothoracic surgeons (CT), and vascular surgeons (VS). Surgeons' annual volume was categorized into low volume (<10 CEAs), medium volume (10 to <30 CEAs), and high volume ( ‡30 CEAs). The primary outcome was 30-day perioperative stroke and/or death; however, other perioperative complications were analyzed. Both univariate and multivariate analyses were done to predict the effect of specialty/volume and any other patient risk factors on stroke outcome. Results: Nine hundred and fifty-three CEAs were performed by 24 surgeons: 122 by seven GS, 383 by 13 CT, and 448 by 4 VS. Patients' demographics/clinical characteristics were similar between specialties, except the incidence of coronary artery disease, which was higher for CT (P < .0001). The indications for CEA were symptomatic disease in 38% for VS, 31% for GS, and 23% for CT (P < .0001). The perioperative stroke and death rates were 4.1%, 2.9%, and 1.3% for GS, CT, and VS, respectively (P [ .126). A subgroup analysis showed that the perioperative stroke rates for symptomatic patients were 5.3%, 2.3%, and 2.3% (P [ .511) and for asymptomatic patients were 3.6%, 3%, and 0.72% (P [ .099) for GS, CT, and VS, respectively. Perioperative stroke rates were significantly higher for nonvascular surgeons (GS and CT combined) vs VS in asymptomatic patients (3.2% vs 0.72%; P [ .033). Perioperative stroke/death was also significantly lower for high-volume surgeons: 1.3% vs 4.1% and 4.3% for medium-and low-volume surgeons (P [ .019) (1.3% vs 4.15% for high vs low/medium combined; P [ .005). More CEAs were done for asymptomatic patients in the low/ medium-volume surgeons (78%) vs high-volume surgeons (64%; P < .0001) with a stroke rate of 4.6% for low/mediumvolume surgeons vs 0.51% for high-volume surgeons (P [ .0005). A univariate logistic analysis showed that the odds ratio of having a perioperative stroke was 0.3 (95% confidence interval [CI], 0.13-0.73; P [.008) for high-volume surgeons vs low/medium-volume surgeons, 0.4 (95% CI, 0.16-1.07; P [ .069) for VS vs CT/GS and 0.2 (95% CI, 0.06-0.45; P [ .0004) when patching was used. A multivariate analysis showed that the odds ratio of having a perioperative stroke for CT VS was 2.1 (95% CI, 0.71-5.92; P [ .183); for GS vs VS, 1.8 (95% CI, 0.49-6.90; P [ .3709); for low-volume surgeons (vs high-volume) 3.4 (95% CI, 0.96-11.77; P [ .0581); medium-vs high-volume surgeons 2.2 (95% CI, 0.75-6.42; P [ .1509). Conclusions: High-volume surgeons had significantly better perioperative stroke/death rates for CEA than low/mediumvolume surgeons. Perioperative stroke/death rates were also higher for nonvascular surgeons in asymptomatic patients. (J Vasc Surg 2013;58:666-72.)

The influence of surgical specialty and caseload on the results of carotid endarterectomy

Journal of Vascular Surgery, 1986

Carotid endarterectomy is rapidly becoming one of the most commonly performed major surgical operations in the United States, in part because of the greater availability of noninvasive techniques to accurately diagnose extracranial carotid arterial disease and a low reported morbidity and mortality. We retrospectively reviewed the records for all carotid endarterectomies performed in the greater Cincinnati area for a recent 12-month period and examined the impact of surgical specialty and operative caseload on the results. Altogether, 750 operations were Performed on 656 patients by 61 surgeons working in 16 general medical,surgical hospitals. Overall, strokes occurred in 5.1% of all patients; 2.3% of patients died. Symptomatic patients had a significantly higher risk of suffering a postoperative stroke compared with asymptomatic patients (6.5% vs. 3.7%), although the risk of death was virtually identical (2.4% vs. 2.1%). When the operating surgeons were classified into four types on the basis of their previous training, no statistically significant differences in either postoperative stroke or death could be identified. Furthermore, when the surgical caseloads of these physicians were grouped into three categories (i.e., less than 12 each year, more than 50 each year, and a group between these two extremes), no significant differences in outcome were seen. We concluded that our community-wide results for carotid endarterectomy were not comparable to those previously published from specialized centers and that these results did not appear to be influenced by the type of formal surgical specialty or operative caseload.

Surgeon volume as an indicator of outcomes after carotid endarterectomy

Journal of the American College of Surgeons, 2002

BACKGROUND: High-volume hospitals have been shown to have superior outcomes after carotid endarterectomy (CEA), but the contribution of surgeon volume and specialty practice to CEA outcomes in a national sample is unknown. patients who underwent CEA (ICD-9-CM code 3812) and had data for unique surgeon identification were studied. Surgeons were categorized in terms of annual CEA volume as low-volume surgeons (Ͻ 10 procedures), medium-volume surgeons (10 to 29), and high-volume surgeons (Ն 30). Data from cardiac, general, neurologic, and vascular surgical practices were analyzed. In-hospital mortality, postoperative stroke, and prolonged length of stay (Ͼ 4 days) were the primary outcomes variables. Unadjusted and case-mix adjusted analyses were performed.

Determinants of outcome after carotid endarterectomy

1998

Background: The efficacy of carotid endarterectomy for selected patients has been evaluated with randomized controlled clinical trials. The generalizability of these studies to average surgical practice remains an important public health concern. Objective: The objective of the study was to determine the predictors of outcome after carotid endarterectomy on a regional basis. Patients and Methods: The study was designed as a retrospective cohort study and included all consecutive patients presented for carotid endarterectomy at the 8 University of Toronto-affiliated hospitals in the period from The main outcome measure was 30-day postoperative stroke or death rate. Results: During the study interval, 1280 primary carotid endarterectomies were performed. The overall combined stroke and death rate was 6.3% for all patients who underwent endarterectomy (4.0% for patients who were asymptomatic). The significant predictors of poor outcome were the following: presenting symptoms (odds ratio, 1.74; 95% confidence interval [CI], 0.96, 3.12), low surgeon volume (<6 cases per year; odds ratio, 3.98; 95% CI, 1.65, 9.58), and left-sided surgery (odds ratio, 1.72; 95% CI, 1.07, 2.76). Conclusion: These data suggest that adoption of the recommendations of the symptomatic carotid endarterectomy trials is appropriate. However, endarterectomy for asymptomatic lesions remains of uncertain benefit on a regional basis and must be individualized to the experience of the specific surgeon. The surgeon volume/outcome relationship that is identified in this study suggests a need for a minimum volume threshold for this procedure. (J Vasc Surg 1998;28:1051-8.)

The Impact of Surgical Specialty on Outcomes for Carotid Endarterectomy

Journal of Surgical Research, 2010

Background. Carotid endarterectomy (CEA) is one of the most frequently performed surgical procedures in the United States. Traditionally, this procedure has been performed by surgeons in at least four specialties. The purpose of this study was to examine the effect of surgeon specialty on the long-term outcomes of CEA among patients receiving the procedure in Pennsylvania.

Predicting complications of carotid endarterectomy

Stroke, 1993

Carotid endarterectomy has been shown to be beneficial in patients with high-grade carotid stenosis and ipsilateral transient ischemic attack or stroke. This benefit will be realized only if the operation is performed safely. We sought to determine the extent to which clinically significant adverse events occurring after carotid endarterectomy can be predicted from clinical data available before surgery. Eleven hundred sixty patients were randomly selected from all patients who underwent carotid endarterectomy and were discharged during the calendar years 1988, 1989, and 1990 in 12 academic medical centers in 10 states. Clinical data abstracted from hospital charts were analyzed retrospectively. A model was developed and validated to predict the occurrence of stroke, myocardial infarction, or death during the postoperative period of hospitalization. Eight patients (6.9%) suffered at least one adverse event. Rates for individual complications were as follows: death, 1.4%; nonfatal st...

The changing face of carotid endarterectomy

Journal of Vascular Surgery, 1996

Purpose: The economic milieu and improvements in care have altered the diagnostic and therapeutic algorithm of the patient with carotid stenosis. This study analyzes the efficacy and safety of these changes. Methods:The records of patients who underwent 320 consecutive carotid endarterectomies performed by three surgeons at our institution from 1990 to 1994 were reviewed retrospectively. Use of diagnostic angiography, use of carotid duplex ultrasound, length of hospital stay, postanesthesia recovery observation, intensive care unit (ICU) observation, complications, and hospital charges were analyzed. Results: The average length of hospital stay decreased from 6.18 days to 2.00 days (p < 0.001). The day of discharge decreased from 3.10 days to 1.24 days after surgery (p < 0.01). By 1993, 68% were discharged by the first day after surgery, increasing to 73% by 1994. From 1990 to 1992, average postoperative ICU observation time fluctuated between 18 and 25 hours; this time decreased to 12.2 hours by 1994. In 1993, only 12.5.% of patients were admitted to the ICU, down from 94.8% in 1990; by 1994, only 7.3% were admitted to the ICU (p --0.001). Postanesthesia recovery observation time decreased from 3.77 hours to 1.63 hours during this time (p_< 0.04). With regard to preoperative diagnosis, angiography was performed in 93.1% of patients in 1990; by 1994, only 32.8% underwent this procedure (p _< 0.0001). Average hospital charges decreased significantly (1990, 14,378;1994,14,378; 1994, 14,378;1994,10,436) with these modifications in patient care (p _< 0.001). The complication rate reflected no significant changes over the course of the study. There were six incidences of cerebrovascular accident (6/320, 1.9%), including one death. There were four incidences of transient ischemic attack (4/320, 1.3%), with no significant differences noted from year to year. Conclusions: This study confirms the changing nature of carotid endarterectomy and documents that these changes have not adversely affected the safety of the operation. (J VASC SURG 1996;23:622-7.) From the

Surgeon specialty and patient outcomes in carotid endarterectomy

Journal of Neurosurgery

OBJECTIVEThe goal of this study was to compare outcomes of carotid endarterectomy performed by neurological, general, and vascular surgeons.METHODSThe authors identified 80,475 patients who underwent carotid endarterectomy between 2006 and 2015 in the National Surgical Quality Improvement Program, a prospectively collected, national clinical database with established reproducibility and validity. Nine hundred forty-three patients were operated on by a neurosurgeon; 75,649 by a vascular surgeon; and 3734 by a general surgeon. Preoperative and intraoperative characteristics and 30-day outcomes were stratified by the surgeon’s primary specialty. Using propensity scores, comprising pre- and intraoperative characteristics as well as procedure and diagnostic codes, the authors matched 203 neurosurgery (NS) patients to 203 vascular surgery (VS) patients and 203 NS patients to 203 general surgery (GS) patients. No pre- or intraoperative factors were significantly different between specialti...

Patient flow to carotid endarterectomy: hastening the patient journey

ANZ Journal of Surgery, 2010

Background: Early carotid endarterectomy (CEA) after stroke or transient ischaemic attack is the proposed standard of care to prevent recurrent ischaemic events in selected patients. The aim of this study was to investigate if this standard is achieved in a tertiary vascular unit. Methods: This was a clinical audit. CEAs performed from 1 January 2006 to 31 December 2008 at Christchurch hospital were identified. The value stream from initial presentation to surgery was mapped in two phases (phase 1; 2006-2007 and phase 2; 2008). Patients who had carotid intervention for asymptomatic carotid lesions were excluded. Results: The relevant patient journey was documented in 81 patients (55 phase 1; 26 phase 2). Median time from initial presentation to carotid ultrasound was 5 days in phase 1 and 6 days in phase 2. Time from presentation to vascular surgery review was 22 days in phase 1 and 13 days in phase 2. Time from presentation to CEA significantly reduced from 83 to 32 days between phases (P < 0.005). Conclusions: There has been a significant decrease in time from presentation to operation between phase 1 and 2. The most significant change is reduced delay between vascular surgery review and CEA. There has been no improvement in urgency of referral for imaging or surgical review. This part of the patient journey is a target for improvement.