Vascular surgery training in the United States, 1994 to 2003

ObjectiveThe purpose of this study was to analyze the use of operative training resources for vascular surgery residents (VSRs) and general surgery residents (GSRs) over the past 10 years in the United States, to address questions concerning adequate endovascular versus open surgical training and the potential to expand the number of VSRs to meet future workforce needs.MethodsNational operative data from the Residency Review Committee for Surgery (RRC) were analyzed for all vascular surgery (VS) and general surgery (GS) training programs from 1994 to 2003. GSR experience in programs with and without associated VS programs was also compared.ResultsMean total VS volume per VSR increased from 220 operations in 1994 to 368 in 2003, owing to the addition of 140 endovascular procedures by 2003. GSR volume was more stable, with 117 mean total VS operations in 1994 and 122 in 2003. This volume was distributed as approximately 50% major open VS operations for both VSR and GSR. In addition, 39% of VSR experience was endovascular, whereas 32% of GSR experience was vascular access. The average VSR performed 2.7 times more major open VS operations than each GSR, but because of the 10-fold greater number of GSRs, VSRs performed only 20% of the total major operations available for VS training. Selective procedures, such as renal revascularization and open infrarenal abdominal aortic aneurysm repair decreased over time, while endovascular abdominal aortic aneurysm repair increased dramatically, accounting for 46% of aortic aneurysm repairs per VSR in 2003. The mean volume of total interventional procedures per VSR in 2003 was 152 diagnostic and 213 therapeutic. GSRs in programs with and without an associated VS program had very similar operative volumes.ConclusionsInterventional procedures have increased VSR operative volume by 50% in recent years, with only a 12% decrease in major open operations. Nearly all VSRs currently meet RRC minimum requirements for open and endovascular procedures. Mean GSR operative volume has been stable, and far exceeds RRC minimum requirements. Based on the number of major open vascular operations available for training in 2003, the current number of VSR positions could be increased by 50% if GSR operative volume was decreased by 15%. However, increased interventional volume would also be required, for which there is competition with other specialties

Factors associated with stroke or death after carotid endarterectomy in Northern New England

ObjectiveThis study investigated risk factors for stroke or death after carotid endarterectomy (CEA) among hospitals of varying type and size participating in a regional quality improvement effort.MethodsWe reviewed 2714 patients undergoing 3092 primary CEAs (excluding combined procedures or redo CEA) at 11 hospitals in Northern New England from January 2003 through December 2007. Hospitals varied in size (25 to 615 beds) and comprised community and teaching hospitals. Fifty surgeons reported results to the database. Trained research personnel prospectively collected >70 demographic and clinical variables for each patient. Multivariate logistic regression models were used to generate odds ratios (ORs) and prediction models for the 30-day postoperative stroke or death rate.ResultsAcross 3092 CEAs, there were 38 minor strokes, 14 major strokes, and eight deaths (5 stroke-related) ≤30 days of the index procedure (30-day stroke or death rate, 1.8%). In multivariate analyses, emergency CEA (OR, 7.0; 95% confidence interval [CI], 1.8-26.9; P = .004), contralateral internal carotid artery occlusion (OR, 2.8; 95% CI, 1.3-6.2; P = .009), preoperative ipsilateral cortical stroke (OR, 2.4; 95% CI, 1.1-5.1; P = .02), congestive heart failure (OR, 1.6; 95% CI, 1.1-2.4, P = .03), and age >70 (OR, 1.3; 95% CI, 0.8-2.3; P = .315) were associated with postoperative stroke or death. Preoperative antiplatelet therapy was protective (OR, 0.4; 95% CI, 0.2-0.9; P = .02). Risk of stroke or death varied from <1% in patients with no risk factors to nearly 5% with patients with ≥3 risk factors. Our risk prediction model had excellent correlation with observed results (r = 0.96) and reasonable discriminative ability (area under receiver operating characteristic curve, 0.71). Risks varied from <1% in asymptomatic patients with no risk factors to nearly 4% in patients with contralateral internal carotid artery occlusion (OR, 3.2; 95% CI, 1.3-8.1; P = .01) and age >70 (OR, 2.9; 95% CI, 1.0-4.9, P = .05). Two hospitals performed significantly better than expected. These differences were not attributable to surgeon or hospital volume.ConclusionSurgeons can “risk-stratify” preoperative patients by considering the variables (emergency procedure, contralateral internal carotid artery occlusion, preoperative ipsilateral cortical stroke, congestive heart failure, and age), reducing risk with antiplatelet agents, and informing patients more precisely about their risk of stroke or death after CEA. Risk prediction models can also be used to compare risk-adjusted outcomes between centers, identify best practices, and hopefully, improve overall results

Distribution of intrarenal blood flow during bacterial Sepsis

Inappropriate polyuria during bacterial sepsis represents a poorly understood clinical entity. This study employed live Pseudomonas aeruginosa infusion to simulate this disorder in awake dogs. Intrarenal blood flow distribution was measured using radioactivity labeled microspheres. Hypotension, leucopenia, hemoconcentration, pyrexia, polyuria, and natriuresis were produced. Most dogs showed increased total renal blood flow. Redistribution of renal blood flow away from the outer cortex toward the juxtamedullary cortex, as well as increased absolute perfusion of the juxtamedullary cortex, occurred. Washout of the medullary interstitial concentration gradient by increased blood flow can explain the observed diuresis. These results support but do not prove a causal relationship between redistributed intrarenal blood flow and polyuria during bacterial sepsis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22641/1/0000192.pd

The effect of bacterial pyrogen on the distribution of intrarenal blood flow

Hemodynamic and biochemical measurements were made before and 90 min after 50 [mu]g of Pseudomonas-derived pyrogen was infused into nine awake dogs. Six control dogs received no pyrogen. Total renal blood flow (RBF) and intrarenal distribution of blood flow to four equal cortical zones (outer to juxtamedullary) were determined by the radioactive microsphere method. Pyrogen administration produced tachycardia, pyrexia, polyuria, natriuresis, and increased RBF. Cardiac output, arterial pressure, hematocrit, creatinine clearance, and white blood cell count did not change significantly. Despite increased total RBF, distribution of blood flow within the renal cortex did not change significantly after pyrogen administration. When compared with the effect of live bacteria, these studies suggest that polyuria and natriuresis result from any increased juxtamedullary blood flow without being dependent on redistribution, per se. Furthermore, the detrimental renal effect of bacterial sepsis may be related to the relative outer cortical hypoperfusion in contrast to the benign renal effect of pyrogen where no redistribution of blood flow occurs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23620/1/0000583.pd

Hemodynamic effects of cecal ligation sepsis in dogs

Cecal ligation sepsis was studied in eight pentobarbital-anesthetized dogs with hemodynamic measurements at baseline, 2 days after cecal ligation, and following Ringer's lactate resuscitation. Microsphere techniques were used to measure peripheral arteriovenous (A-V) shunting and distribution of cardiac output. Cecal ligation sepsis was manifested by pyrexia, leukocytosis, decreased blood pressure, and purulent peritonitis. Although cardiac index (CI) increased in two, decreased in four, and was unchanged in two dogs, femoral artery blood flow (FAQ) decreased in all animals (125 to 84 ml/min, P 2 difference increased while O2 consumption and A-V shunting did not change. Distribution of cardiac output increased significantly to the kidneys (163%, P P 2 differences returned to baseline values. Hindlimb A-V shunting remained low and unchanged.In contrast to the effects of local inflammation in canine septic hindlimbs, there does not appear to be a specific vasodilator released during cecal ligation sepsis which causes increased peripheral blood flow and elevated A-V shunting. Cecal ligation in dogs, however, does not mimic the disproportionately low peripheral resistance and reduced O2 extraction seen in hyperdynamic human sepsis. These results should, therefore, be interpreted with caution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23853/1/0000092.pd

Effect of intravenous glucagon on the survival of rats after acute occlusive mesenteric ischemia

The purpose of this study was to determine the optimal timing of intravenous glucagon infusion for the treatment of acute occlusive mesenteric ischemia. The superior mesenteric artery (SMA) was occluded for 85 min in 106 Sprague--Dawley anesthetized rats. The animals were divided into 12 treatment groups according to the timing of glucagon and saline administration, and survival was measured to 48 hr. Without treatment, all rats died within 24 hr. Intravenous saline (10 ml/kg/hr) for 2 hr did not significantly improve 48-hr survival (17-33%). Glucagon (1.6 [mu]g/kg/min iv) plus saline (10 ml/kg/hr iv) for 2 hr after SMA occlusion significantly improved survival from 33% (saline control) to 83% (P P &lt; 0.02). Adequate saline infusion was required for glucagon efficacy after ischemia, as shown by an intermediate 48-hr survival of 50% when only maintenance saline (1.5 ml/kg/hr) was given. These data suggest that glucagon therapy should be delayed until after operative release of an acute SMA occlusion and should be accompanied by vigorous volume expansion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25685/1/0000239.pd

“Medical high risk” designation is not associated with survival after carotid artery stenting

BackgroundWhile medical high risk (MHR) has been proposed as an indication for carotid artery stenting (CAS), the impact of MHR on long-term survival and stroke after CAS has not been described.MethodsA retrospective chart review of CAS procedures at our institution was performed. One hundred seventy-nine consecutive patients who underwent 196 CAS procedures were classified by MHR status based on cardiac, pulmonary, and renal criteria routinely used in high-risk clinical trials. Survival and stroke rates were compared after 90 CAS procedures in MHR patients vs 106 CAS procedures in normal risk patients. Survival results were also compared with 365 contemporaneous carotid endarterectomy (CEA) procedures in 346 patients.ResultsThe mean age of CAS patients was 72 years, with 87% having a smoking history, 85% hypertension, 38% diabetes, 39% symptomatic, and 74% documented coronary artery disease. Mean follow-up was 23 months. Recurrent stenosis after CEA comprised 21% of all CAS procedures. During the 30-day post-procedure period, there were five minor strokes, one major stroke, and one death, for a combined stroke/death rate of 3.6%. Kaplan-Meier analysis demonstrated mortality of 5% at 1 year and 21% at 3 years for the entire cohort. Cox regression analysis found that MHR designation was not associated with increased mortality or an increase in a composite end point of death or stroke. MHR patients had mortality of 4% at 1 year and 22% at 3 years. Normal risk patients had mortality of 6% at 1 year and 20% at 3 years. Preoperative age over 80 years old, low density lipoprotein (LDL) ≥160 mg/dL, and serum creatinine ≥1.5 mg/dL conferred statistically significant risk for death (Hazard ratios: 2.9, 4.3, and 2.4, respectively). As a point of comparison, a contemporaneous group of CEA patients were analyzed similarly. After adjusting for age over 80 years old and serum creatinine ≥1.5 mg/dL, there was no survival difference between MHR patients undergoing CAS or CEA.ConclusionsThe presence of MHR did not impact long-term survival or stroke rate after CAS, and overall survival of MHR patients in our series was comparable with risk-adjusted controls undergoing CEA. These results suggest the need for more refined predictors of medical risk to optimally guide patients in selecting carotid revascularization strategies