Effects of surface charge and cluster size on the electrochemical dissolution of platinum nanoparticles using COMB3 and continuum electrolyte models

We study the site-dependent dissolution of platinum nanoparticles under electrochemical conditions to assess their thermodynamic stability as a function of shape and size using empirical molecular dynamics and electronic-structure models. The third-generation charge optimized many-body potential is employed to determine the validity of uniform spherical representations of the nanoparticles in predicting dissolution potentials (the Kelvin model). To understand the early stages of catalyst dissolution, implicit solvation techniques based on the self-consistent continuum solvation method are applied. It is demonstrated that interfacial charge and polarization can shift the dissolution energies by amounts on the order of 0.74 eV depending on the surface site and nanoparticle shape, leading to the unexpected preferential removal of platinum cations from highly coordinated sites in some cases.

Effects of a standardized emergency department protocol on after-hours use of venous duplex ultrasound

OBJECTIVE

Vascular laboratory (VL) venous duplex ultrasound is the "gold standard" for diagnosis of lower extremity deep venous thrombosis (DVT), which is linked to many morbid conditions. Decreasing night and weekend use of VL services in the emergency department (ED) represents a potentially viable means of reducing costs as skilled personnel must remain on call and receive a wage premium when activated. We investigated the effects of workflow changes that required ED providers to use a computerized decision-making tool, integrated into the electronic medical record, to calculate a Wells score for each patient considered for an after-hours venous duplex ultrasound study for suspected DVT.

METHODS

The rate of VL use and study positivity before and after implementation of the decision-making tool were examined in addition to measures of ED throughput, rate of concomitant pulmonary embolism, disposition of examined patients from the ED, observed thrombus distribution in duplex ultrasound studies positive for DVT, and calculated personnel costs of after-hours VL use.

RESULTS

A total of 391 after-hours, ED-initiated venous duplex ultrasound studies were obtained during the 4-year study period (n = 213 before intervention, n = 178 after intervention; P = .12). Whereas the period immediately after the start of the intervention saw a decrease in VL use, this was not sustained. Studies performed after the intervention were not more likely to be positive for acute DVT (12.2% vs 18%; P = .1179). The average Wells score was 2.8 (range, 0-6). VL personnel were called in 347 times during the 4-year period, with a total cost of $14,643.40. Nurse-ordered studies were significantly more likely to be positive, with 22% revealing acute DVT compared with 12% for physician-ordered studies (P = .042). The intervention resulted in significant improvements in ED throughput, with time between triage and study request falling from 226 minutes to 165 minutes (P < .001). Observed thrombus distribution revealed involvement of the most proximal external iliac system in a minority of cases (11%), whereas most thrombi (89%) were limited to the femoropopliteal, calf, and superficial venous systems.

CONCLUSIONS

A requirement for ED providers to document a Wells score before obtaining an after-hours venous duplex ultrasound study resulted in only a transient decrease in VL use but improved ED throughput. Studies ordered by nurses were significantly more likely to be positive, possibly as a result of consistent protocol adherence compared with the physicians. Future studies may warrant investigation into this provider variance.

Repair of Bilateral Iliac Artery Aneurysms Associated with a Congenital Pelvic Kidney

The association of iliac artery aneurysms with a congenital pelvic kidney is extremely rare. Although multiple techniques are well described for renal preservation with renal ectopia in the setting of aortic reconstruction, few reports exist describing techniques for renal preservation in the setting of bilateral iliac artery aneurysms. A case is presented of a middle-aged man with a 6-cm right common iliac artery aneurysm and a 3-cm left common iliac artery aneurysm and a right pelvic kidney. A double-proximal-clamp technique and temporary shunting to the pelvic kidney were used during the aneurysm repair. The technical aspects of this procedure are presented as well as a brief discussion of the various options for renal preservation with renal ectopia when repairing complex aneurysmal disease.

Interdisciplinary Quality Improvement Conference: Using a Revised Morbidity and Mortality Format to Focus on Systems-Based Patient Safety Issues in a VA Hospital: Design and Outcomes

The Veterans Healthcare Administration (VA) has embraced patient safety and quality improvement in the quest to improve care for veterans. The New Mexico VA Health Care System introduced a new morbidity and mortality conference, called the Interdisciplinary Quality Improvement Conference (IQIC), using patient case presentations to focus on underlying systems in the clinical care environment. The revised conference design also effectively teaches the 6 Accreditation Council for Graduate Medical Education (ACGME) core requirements for resident education. A formal process was established for case selection, presentation, systems issue identification, tracking, and follow-up. The IQIC has enabled the identification of more than 20 system issues at the study institution. Outcome data show lasting improvement in system issues that were addressed by this mechanism. The VA IQIC is an effective method to both identify and correct systems issues that affect patient care and is an effective method for teaching residents the 6 ACGME requirements for residency education.

Long-term follow-up of endovascular abdominal aortic aneurysm repair in a rural veteran patient population

BACKGROUND

The endovascular repair of abdominal aortic aneurysms (EVARs) requires follow-up to detect and treat late complications.

METHODS

Two hundred eleven patients underwent EVAR for infrarenal, nonruptured abdominal aortic aneurysms from 1999 to 2010 at the Raymond G. Murphy VA Medical Center, Albuquerque, NM. A retrospective review examined patient demographics, comorbidities, the distance the patient lived from the facility, early and late complications, and the device implanted. Statistical analysis included the chi-square test for independence, the Fisher exact test, and the 2-sample Mann-Whitney U test for means.

RESULTS

The mean time from the operation to the first complication was 21 months (standard deviation = 20 months) with a mean follow-up of 48 months (standard deviation = 36 months). The late complication rate was 22.8% (54 patients). Sixteen percent did not require any reinterventions, 57% were treated with percutaneous interventions, and 27% required an open surgical procedure. No single comorbidity, combination of comorbidities, distance the patient lived from the facility, or device implanted was predictive of complications.

CONCLUSIONS

EVAR follow-up is essential to detect complications. When complications occur, the majority occur well after the initial treatment, and most can be treated with minimally invasive percutaneous techniques.

Endoscopy in a deployed combat support hospital: maintaining military end-strength

OBJECTIVE

The objective was to examine the safety and efficacy of the 48th Combat Support Hospital's use of diagnostic endoscopy in Afghanistan.

METHODS

A retrospective review was performed on the medical records of all endoscopy patients treated at the 48th Combat Support Hospital in Bagram, Afghanistan, from December 6, 2002 through June 7, 2003.

RESULTS

Twenty-four patients (male, 21; female, 3; mean age, 35 years) underwent 28 endoscopic procedures as follows: colonoscopy, 14; esophagogastroduodenoscopy (EGD), 13; and flexible sigmoidoscopy, 1. Four patients underwent both EGD and colonoscopy. There were no complications. Of the 18 U.S. military patients, 3 (15%) were evacuated for further evaluation and/or treatment and 1 (5%) patient underwent an elective screening colonoscopy. For 14 of 17 U.S. military personnel (82%), the endoscopic procedures obviated evacuation from Afghanistan.

CONCLUSIONS

Diagnostic colonoscopy and EGD were valuable and safe adjuncts that precluded evacuations out of theater for 82% of military patients. Endoscopy should be used when U.S. military operations necessitate the deployment of large numbers of forces for protracted periods.

Operation Enduring Freedom: the 48th Combat Support Hospital in Afghanistan

OBJECTIVE

To examine the experience of the 48th Combat Support Hospital (CSH) while deployed to Afghanistan, with an emphasis on trauma care.

MATERIALS AND METHODS

Before redeployment, a retrospective review was performed on the medical records of all patients treated at the 48th CSH from December 6, 2002 through June 7, 2003.

RESULTS

During the 6-month period, 10,679 patients were evaluated and/or treated. There were 477 hospital admissions (adults, 387; children, 90; trauma, 204) and 634 operating room procedures. The most common mechanisms of injury were land mines/unexploded ordinance (74 = 36%) and gunshot wounds (41 = 20%). Extremities were the most common site. A total of 358 cases was performed on 168 trauma patients (mean, 2 cases per patient; range, 1-12). There were 63 complications in 40 trauma patients and 11 patients died.

CONCLUSIONS

The 48th CSH supported military and humanitarian operations with an ongoing process of re-evaluation, adaptation, and medical education that resulted in low morbidity and mortality rates.

What imaging studies are necessary for abdominal aortic endograft sizing? A prospective blinded study using conventional computed tomography, aortography, and three-dimensional computed tomography

OBJECTIVE

Preoperative imaging modalities for endovascular abdominal aortic aneurysm repair (EVAR) include conventional computed tomography (CT), aortography with a marking catheter, and three-dimensional computed tomography (3D CT). Although each technique has advantages, to date no study has compared in a prospective manner the reproducibility of measurements and impact on graft selection of all three modalities. The objective of this study was to determine the most useful imaging studies in planning EVAR.

METHODS

Twenty patients being considered for EVAR were enrolled prospectively to undergo a conventional CT scan and aortography. The CT scans were then reconstructed into 3D images using Preview Treatment Planning Software (Medical Media Systems, West Lebanon, NH). Four measurements of diameter and six of length were made from each modality in determining the proper graft for EVAR.

RESULTS

Measurements from all three modalities were reproducible with intraobserver correlation coefficients of 0.79 to 1.0 for aortography, 0.87 to 1.0 for CT, and 0.96 to 1.0 for 3D CT. Measurements between observers were also similar from each modality; interobserver correlations were 0.70 to 0.97 for aortography, 0.76 to 0.97 for CT, and 0.73 to 0.99 for 3D CT. Significant differences ( P < .01) in diameter measurements were noted at D2 with aortography compared with 3D CT, whereas differences in length measurements were found between CT and 3D CT at L4 (nonaneurysmal right iliac) ( P < .01). The correlation between CT and 3D CT for most length measurements was acceptable (0.63 to 1.0). Aortography for diameters correlated poorly (0.35 to 0.67) with 3D CT. When the endograft selected by aortography/CT or 3D CT alone was compared with the actual endograft used, there was agreement in 11 of 11 patients when adjusted for +/- one size in diameter or length.

CONCLUSION

Reproducible and comparable measures of diameter and length can be obtained by each of three imaging modalities available for endograft sizing. As a single imaging modality, 3D CT appears to have the best correlation for both diameters and lengths; however, the difference is not sufficient enough to alter endograft selection. Three-dimensional CT may be reserved for challenging aortic anatomy where small differences in measurements would affect patient or graft selection for EVAR.

Endovascular Management of a Peroneal Artery Injury Due to a Military Fragment Wound

A healthy 29-year-old male suffered bilateral lower extremity fragment wounds resulting in a tense right calf shortly following a wound that required a four-compartment fasciotomy. During treatment of other injuries after medical evacuation he complained of increasing right calf pain. A peroneal pseudoaneurysm (PSA) with a concomitant arteriovenous fistula (AVF) was diagnosed. The distal one-third of the peroneal artery was not visualized, and the posterior tibial and anterior tibial arteries were normal. The patient underwent percutaneous coil embolization of the pseudoaneurysm. Completion arteriography demonstrated no evidence of the PSA and AVF. The patient's bruit and pain resolved.

Re-evaluation of carotid duplex for visual complaints: who really needs to be studied?

Amaurosis fugax (AF), Hollenhorst plaques, central retinal artery occlusion (CRAO), and nonspecific visual symptoms are all reasons for patient referral for carotid artery evaluation. This study reviews the management of patients with visual signs or symptoms based on their clinical presentation, carotid duplex results, follow-up data, and outcome. We performed a retrospective review of all patients presenting to the Vascular Surgery Clinic between June 1996 and December 2001 for carotid duplex scanning because of the indication of a visual disturbance. A total of 3560 carotid duplex examinations were performed during the study period; 98 were performed for a visual complaint or finding. A total of 11.1% of group 1 (Hollenhorst plaques), 22.2% in group 2 (CRAO), 45% in group 3 (AF), and 9.8% in group 4 (nonspecific visual symptoms) had significant carotid disease and underwent carotid endarterectomy. No patient who underwent screening carotid duplex and did not have surgically correctable disease developed significant carotid disease or symptoms from carotid disease during the study period. Hollenhorst plaques, CRAO, and nonspecific visual complaints are a poor predictor of significant carotid stenosis, while AF had a significantly higher rate of surgically correctable carotid stenosis. Patients with visual signs or symptoms need an initial screening carotid duplex examination. If this does not show surgically correctable disease, patients do not need to return for further examinations unless another indication arises.

Endovascular assisted in situ bypass grafting: a simplified technique for saphenous vein side branch occlusion

The in situ bypass procedure for lower extremity limb salvage requires a long continuous incision or multiple interrupted incisions over the greater saphenous vein to ligate the saphenous vein side branches. This can result in wound complications that frequently prolong hospital stay and threaten the graft. In an effort to reduce the incidence of wound complications, alternate methods of occluding the vein side branches have been used. One method is to deliver coils under angioscopic vision into the saphenous vein side branches. This report details a simplified technique that uses widely available catheter-based equipment to perform saphenous vein side branch occlusion under fluoroscopic guidance.

Percutaneous arterial closure in peripheral vascular disease: a prospective randomized evaluation of the Perclose device

BACKGROUND

Patients with peripheral vascular disease have been excluded from initial studies of percutaneous suture-mediated closure devices (SMCD) despite representing a significant proportion of those requiring endovascular intervention. We sought to determine whether these devices could be safely used in patients with peripheral vascular disease.

METHODS

Patients were stratified into two groups and five subgroups on the basis of indication for arteriography, and they were prospectively randomized at the end of the procedure to receive either the SMCD or manual compression. Ankle-brachial index was determined and duplex ultrasound scanning of the accessed femoral artery was performed, before and after the procedure. Ultrasound data included peak systolic velocity, minimum intraluminal vessel diameter, and presence or absence of calcified plaque. Time to hemostasis, ambulation, and discharge were recorded, and major or minor complications were noted.

RESULTS

Of 102 patients included in the study, 52 patients were randomized to receive the SMCD. There was no difference in ankle-brachial index, minimum intraluminal vessel diameter, or peak systolic velocity in the accessed vessel after closure with SMCD or manual compression. Time to hemostasis, ambulation, and discharge was significantly less in the SMCD group (P =.001). Presence of calcified plaque was not associated with complications (P =.146). In the SMCD group, hemostasis was achieved with 49 of 52 devices (94.2%). There were six complications (5.9%), two of which were major and required operative intervention. All complications were hemorrhagic and not occlusive. There was no difference in overall complication rate between SMCD (7.7%) and manual compression (4.0%) groups (P =.678). No infection was noted in any of the 102 patients.

CONCLUSIONS

Suture-mediated percutaneous arterial closure can be safely performed in patients with peripheral vascular disease, even in the presence of calcified plaque. This closure technique enables shorter time to hemostasis, ambulation, and hospital discharge. There are observed differences in minor, but not major, complication rates for MC versus percutaneous arterial closure in patients with peripheral vascular disease, but these differences did not achieve statistical significance in this small series.

Mesenteric venous thrombosis in a patient with prothrombin 20210A mutation and antithrombin III deficiency: challenges to conventional anticoagulation--a case report

Mesenteric venous thrombosis presents as vague abdominal pain in patients with a medical or family history suggestive of a hypercoagulable state. Classic computed tomography findings will often confirm the diagnosis, and the presence of persistent abdominal pain or tenderness will determine the need for surgical intervention. Expeditious anticoagulation is the treatment of choice. This case demonstrates the CT findings for mesenteric venous thrombosis and discusses the challenges of anticoagulation in a patient with 2 hypercoagulable disorders.

Aberrant right subclavian artery syndrome: a case of chronic cough

A young, otherwise healthy man had chronic cough of 16 months' duration. Evaluation revealed an aberrant right subclavian artery. Kommerell's diverticulum without aneurysmal degeneration was present. Imaging studies showed compression of the esophagus but not the trachea. Results of methacholine challenge test were negative for evidence of reactive airway disease, but suggested mild variable intrathoracic obstruction. While aberrant right subclavian artery syndrome most commonly involves dysphagia, our patient's only symptom was cough. Right subclavian artery to right common carotid artery transposition was performed, with oversewing of the subclavian artery stump to the left of the esophagus through a right supraclavicular incision. This treatment was curative, with complete resolution of symptoms.

Review of standards for competence in catheter-based endovascular procedures: a resource and strategy for the interventional vascular surgeon

The field of peripheral vascular disease management is evolving. As such, vascular surgeons can no longer be complacent and expect to be included in the rapidly expanding practice of endovascular intervention. If not engaged, vascular surgeons risk losing not only the patients who have largely driven this evolution but also their role as leaders in the management of vascular disease. Therefore vascular surgeons and vascular surgical training programs find themselves in an awkward and sometimes confrontational circumstance attempting to gain experience and training in catheter-based procedures. Individual societies, both surgical and nonsurgical, have put forth competence standards for catheter-based procedures. However these standards are not always consistent and the definition of competence is often a heated debate. In addition, combining the acquisition of endovascular skills with the multitude of available endovascular training experiences, didactic and "hands-on," is not well coordinated. The objectives of this review are to summarize the literature as it relates to catheter-based endovascular competence, including publications from nonsurgical catheter-based specialties, and to place the acquisition of basic endovascular skills in context with the available endovascular courses in a stepwise strategy. A final objective is to provide a literature-based resource that outlines specific phases in the development of interventional vascular surgeons and training programs as they advance into the arena of catheter-based endovascular therapies.

Preoperative risk stratification using electron beam computed tomography in elective vascular surgery: relationship to clinical risk prediction and postoperative complications

We studied the utility of electron beam computed tomography as a screening test for the cardiovascular risk of elective vascular surgery. In 45 patients undergoing principally carotid and aortic surgical procedures, coronary artery calcification was prevalent and severe, and related to the clinically predicted cardiovascular risk of the procedure. However, only the clinically predicted surgical risk, and not coronary artery calcification, was related to the incidence of perioperative cardiovascular complications.

Endovascular management of renal ischemia in a patient with acute aortic dissection and renovascular hypertension

We report the endovascular management of a patient with a type B aortic dissection complicated by renal ischemia and resultant severe hypertension. A 69-year-old male presented with acute type B aortic dissection with proximal extension complicated by severe renovascular hypertension secondary to left renal ischemia. Endovascular management consisted of imaging with intravascular ultrasound and left renal artery stenting with balloon-expandable stents. His hypertension subsequently resolved and he was discharged on his baseline two-drug regimen. Management of the ischemic complications of type B aortic dissections may be primarily approached using endovascular methods in stable patients, with open surgery reserved for those patients refractory to these methods. Patients with evidence of decreased renal perfusion represent a select group with an increased risk of associated morbidity and mortality and should therefore be aggressively managed. Accurate information and assessment of anatomy can be obtained with intravascular ultrasound and is therefore an important adjunct to the armamentarium of endovascular specialists managing complications of aortic dissection.

Bilateral spontaneous dissection of the internal carotid arteries--a case report

A 41-year-old African American man presented with an acute stroke secondary to bilateral spontaneous internal carotid artery dissections following exercise. Spontaneous bilateral carotid artery dissection is an unusual and uncommon occurrence that can be successfully diagnosed by color-flow duplex ultrasonography and magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) imaging. A review of the literature and the authors' experience supports initial medical management of these patients. Surgery should be considered for those patients who exhibit progressive neurologic symptoms during medical management or when significant carotid artery complications, aneurysms, or flow-limiting stenoses persist.

Chronic ergot toxicity: A rare cause of lower extremity ischemia

Chronic ergot toxicity is a rare cause of lower extremity ischemia. The cornerstone of therapy in ergot toxicity is to discontinue the use of caffeine, cigarettes, and all ergot-containing medications. Although multiple different therapies have been recommended for acute toxicity, no specific treatment is uniformly recommended in chronic toxicity. We present a case of long-term ergot use for migraine headaches in a woman who had severe chronic lower extremity claudication. This case demonstrates the unique features associated with the diagnosis and management of chronic ergot toxicity. We recommend a conservative approach consisting of observation, antiplatelet agents, and the discontinuance of ergots. If symptoms progress to rest pain or gangrene, surgical treatment should be considered.

The fate of a patent carotid artery contralateral to an occlusion

The finding of carotid stenosis contralateral to a carotid occlusion is becoming more frequent. While the neurologic outcomes in this patient population have been described, the rate of disease progression measured by duplex examination and the eventual need for carotid endarterectomy has not been described. In this study, a computerized database of carotid duplex examinations was reviewed and clinical data were obtained from clinic records. From 9124 studies 117 patients were identified. Thirty patients had previous carotid surgery on the patent side and were excluded. Of 87 patients 33 required carotid endarterectomy on the patent side. The rate of disease progression and/or the performance of a carotid endarterectomy by life-table analysis was 85.9% over 8 years. There were 10 neurologic events during the follow-up period. Patients with carotid stenosis and contralateral occlusion are at significant risk for disease progression. Follow-up should be more frequent and of longer duration in this patient population. A significant number of patients with carotid artery occlusion will require a carotid endarterectomy of the patent contralateral carotid.

Hemostatic efficacy of fibrin sealant (human) on expanded poly-tetrafluoroethylene carotid patch angioplasty: a randomized clinical trial

PURPOSE

The efficacy of solvent-detergent-treated fibrin sealant (human [FSH]) for controlling anastomotic bleeding from expanded polytetrafluoroethylene (ePTFE) patch angioplasty during carotid endarterectomy was evaluated, and FSH was compared with thrombin-soaked gelatin sponge (Gelfoam; TSG).

METHODS

The study was of a randomized, open-label, single-site, single-treatment, parallel design that took place in a referral center with hospitalized patients. Forty-seven adult patients (33 men, 14 women) underwent elective carotid endarterectomy. Patients were randomized to receive either FSH (N = 24) or TSG (N = 23). FSH was obtained as an investigational new drug. FSH was applied as a liquid by means of a dual-syringe technique. Heparin anticoagulation, patch thickness, and suture type were standardized. Two different needle sizes were used (CV-6, PT-13: N = 21 [FSH: N = 10, TSG: N = 11]; CV-6, PT-9: N = 26 [FSH: N = 14, TSG: N = 13]). The FSH or TSG was applied to the ePTFE patch, and then blood flow was restored through the carotid artery. Degree of anticoagulation was assessed by anti-factor Xa activity. The time from restoration of carotid blood flow until achieving hemostasis was recorded. The blood loss from patch suture hole bleeding was measured. Completion intraoperative duplex ultrasound scanning was performed in all cases. Heparin was reversed with protamine sulfate. The primary end point was successful hemostasis within 15 minutes of restoration of carotid blood flow. The secondary end points were the amount of blood loss caused by suture line bleeding and the time to achieve hemostasis.

RESULTS

There was no difference in the number of patients with complete hemostasis at 15 minutes (TSG, 13 of 23; FSH, 12 of 24; P =.77). The measured blood loss was 99.0 +/- 119.9 (SD) mL for TSG, and 105.0 +/- 107.9 mL for FSH (P =.86). The time to hemostasis was the same for both groups (TSG, 16.5 +/- 16.5 minutes; FSH, 16.6 +/- 14.2 minutes; P =.97). Within both treatment groups, the use of larger needles (PT-13) was associated with greater blood loss (FSH, 169.7 +/- 124.2 mL; TSG, 172.7 +/- 151.5 mL) than was the use of smaller needles (PT-9; FSH, 58.8 +/- 66.3 mL; TSG, 34.1 +/- 25.6 mL; P =.036, P =.001, respectively). There were no postoperative strokes or bleeding complications in either group. No abnormalities were shown in either group by means of completion carotid duplex ultrasound scanning.

CONCLUSION

FSH was equivalent, but not superior to, TSG in achieving hemostasis during carotid endarterectomy performed with ePTFE patch angioplasty. Adhesion properties of FSH to ePTFE are possibly different than those to native tissue and warrant additional investigation.

Physiologic responses of cross-linked hemoglobin in endotoxin-treated rats

Purified human cross-linked hemoglobin (alpha alpha Hb) as well as recombinant human hemoglobin is undergoing clinical trials in the setting of acute blood loss and perioperative hemodilution. We have previously demonstrated that in rabbits with circulating plasma Hb, such as alpha alpha Hb, infusion of endotoxin (LPS) impairs myocardial contractility which results in hypotension, tissue hypoperfusion and increased mortality. The untoward cardiovascular effects occurring after the combined infusion of LPS and alpha alpha Hb in this model are similar to those reported for other agents that inhibit nitric oxide (NO) availability. To determine if the deleterious effects of alpha alpha Hb and LPS were species specific, we performed similar studies in rats. Anesthetized Sprague-Dawley rats received LPS (4 mg/kg or 40 mg/kg) alone or in combination with alpha alpha Hb (0.7 g/kg). Mean arterial blood pressures (MAP) increased in the group that received alpha alpha Hb alone (105 +/- 8 to 120 +/- 7 mm Hg, p = 0.2) and a decrease was noted in the groups that received low dose LPS (4 mg/kg, p = 0.5) and high dose LPS (40 mg/kg, p = 0.016). MAP in rats treated with the LPS at either dose combined with alpha alpha Hb remained unchanged. Levels of urine nitrite, which was measured as a surrogate marker for plasma NO, were significantly decreased at 2 hr in groups that received the combination of alpha alpha Hb and LPS at 4 mg/kg (p = 0.022) and 40 mg/kg (p = 0.003). No significant decrease was observed in animals treated only with alpha alpha Hb (p = 0.21) or LPS (4 mg/kg; p = 0.78 and 40 mg/kg; p = 0.65). Survival was evaluated during 72 hr in animals that were infused with high dose LPS (40 mg/kg) alone or in combination with alpha alpha Hb and then allowed to recover. The survival of rats treated with LPS alone or the combination was 29% at the end of 24 hr and was 100% for rats receiving only alpha alpha Hb. The data suggest that the toxicity of alpha alpha Hb appears to be a species specific phenomenon.

Determination of 60% or greater carotid stenosis: a prospective comparison of magnetic resonance angiography and duplex ultrasound with conventional angiography

The morbidity and cost of conventional angiography (CA) have focused recent efforts in cerebrovascular imaging upon the exclusive use of noninvasive techniques. Our purpose was to prospectively evaluate carotid magnetic resonance angiography (MRA) and to compare its accuracy with color-flow duplex (CFD). Fifty patients were prospectively evaluated with CA and MRA after clinical and CFD findings indicated the need for carotid angiography. CFD measurements of peak systolic velocity (PSV) and end-diastolic velocity (EDV) were made. MRA results were categorized as 0%-39%, 40%-59%, 60%-79%, or 80%-99% stenosis or occluded. Determination of percent carotid stenosis by CA was made as in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). Using receiver operating characteristic (ROC) curves, the probability of correctly predicting a > or =60% stenosis using various CFD thresholds and MRA was assessed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in determining > or =60% stenosis were estimated. For MRA the sensitivity was 85% (95% Confidence Interval [CI] = 69%-94%), specificity 70% (CI = 56%-81 %), PPV 68% (CI = 53%-80%), and NPV 86% (CI = 72%-94%). For CFD the sensitivity was 89% (CI = 74%-96%), specificity 93% (CI = 82%-98%), PPV 89% (CI = 74%-96%), and NPV 93% (CI = 82%-98%). When MRA and CFD results were concordant (n = 64), the sensitivity was 100% (CI = 89%-100%), specificity 95% (CI = 81%-99%), PPV 94% (CI = 77%-99%), and the NPV was 100% (CI = 92%-100%). The area under the ROC curve for CFD was 95%, compared to 83% for MRA (p = 0.0005). We conclude that the low specificity of MRA precludes its use as the definitive imaging modality for carotid stenosis. The 93% specificity of CFD alone warrants its consideration as a definitive carotid imaging study. By ROC curve analysis, CFD offers superior accuracy to MRA. Our data support noninvasive preoperative carotid imaging for detecting a threshold stenosis of > or =60% whether CFD is used alone, or in combination with the selective use of MRA.

Long-term follow-up of a superficial femoral vein injury: a case report from the Vietnam Vascular Registry

We report a 29-year follow-up of a high-velocity superficial femoral vein injury sustained during the Vietnam War that was treated by emergent ligation. After years of suffering recurrent ulceration from chronic venous insufficiency, this patient underwent axillary vein valve transfer with improvement in his venous hypertension. Long-term follow-up of patients with deep venous injuries is necessary to avoid complications from chronic venous insufficiency.

Long-term impact of previous breast biopsy on breast cancer screening modalities

Approximately 80% of breast biopsies are performed for what proves to be a benign process. The patients who undergo these procedures should continue screening with breast physical examination and mammography. The long-term impact of breast biopsy on these screening modalities has not been well studied. We performed a prospective, follow-up evaluation in 63 patients who underwent needle localization biopsy with benign histology at our institution between 6 and 7 years ago. This evaluation consisted of a directed history, breast physical examination, and follow-up mammogram. Two patients (3%) had undergone mastectomy for an interval breast cancer; 17 others (28%) had undergone subsequent biopsies. No patient had changes on physical examination of the biopsy site. All mammograms were evaluated as normal or as having benign abnormalities. Excisional breast biopsy does not generally produce long-term changes affecting the interpretation of breast physical examination or mammography.

Problems in placement of the Greenfield inferior vena cava filter

Placement of an intracaval device is the treatment of choice for failure of, or contraindication to, anticoagulation therapy. A retrospective study of 111 patients from 1980 to 1986 was undertaken to identify the incidence and degree of related complications or problems regarding placement of the device. Ninety seven of 111 (87.4%) patients had no complications or problems in placement; 14/111 (12.6%) patients did have problems. Of the latter group, mechanical problems included eccentric filter placement, insertional difficulty, problems in filter carrier removal, premature discharge, and misplacement. A total of four patients required a second filter. A single instance of worsening renal insufficiency was noted. Of the total group (ages 24 to 97 [means = 62.4] years), other medical problems including diabetes, smoking, malignancy, sepsis, hypertension, and alcoholism had no influence on the complications or problems. The Greenfield filter remains the method of choice for the listed indications; however, an awareness of potential problems may lessen the technical complications. The operative problems did not adversely impact hospital morbidity or cost.

Below-knee physiologic cryoanesthesia in the critically ill patient

Controversy has surrounded the role of local hypothermia as a preoperative treatment in amputations of the lower extremity. A study was undertaken to determine the effectiveness of amputation under cryoanesthesia in decreasing postoperative morbidity and mortality in below-knee (BK) amputations. Of 154 BK amputations, only 91 with unreconstructable vascular disease, gangrene, or both, were included in this study. Group I consisted of 48 patients (mean age 63.9 years) who had undergone a routine BK amputation; group II consisted of 43 patients (mean age 65.7 years) who were acutely ill and too unstable to undergo a major surgical procedure. Group II patients were treated by amputation while under cryoanesthesia before any definitive operative intervention. The patients in group II were significantly (p less than 0.05) more ill preoperatively than those in group I. Group II patients had a higher prevalence of previous myocardial infarction, previous stroke, diabetes mellitus, osteomyelitis, and wet gangrene. Seventy percent of the patients in group II had three or more risk factors vs. 46% in group I. Early postoperative mortality rates did not differ significantly between groups (group I, 8%; group II, 9%); the average length of hospital stay for group I patients was 24.2 days compared with 17.7 days in group II. Group II patients sustained slightly more postoperative complications. Amputation under cryoanesthesia appears to be of value in reducing postoperative morbidity and mortality and length of hospital stay in the acutely ill patient with unreconstructable vascular disease, gangrene, or both.