Surgical removal of a foreshortened right innominate vein Wallstent causing venous outflow obstruction.

OBJECTIVES: Stenting of central venous stenosis to preserve upper extremity hemodialysis access is well-described, though upper extremity complications secondary to these stents are less frequently discussed. METHODS: We present the case of a 43-year-old male with a right brachiocephalic fistula who developed symptoms of venous hypertension following placement of a Wallstent for central venous stenosis. Workup demonstrated venous outflow obstruction secondary to stent foreshortening into the right subclavian vein. RESULTS: The Wallstent was removed in a piecemeal fashion using an open surgical technique and a HeRO graft was placed for dedicated fistula outflow with complete relief of the patient's symptoms. CONCLUSION: In situations where a stent has migrated and endovascular removal is not possible, individual Wallstent fibers can be removed through a limited venotomy.

Norepinephrine-Induced Peripheral Ischemia Leading to Gangrene: A Case Series.

ABSTRACT: Norepinephrine is used in the acute care setting to establish and maintain hemodynamic stability in patients with hypotension. Although it is often a lifesaving medication, norepinephrine may lead to profound vascular insufficiency in the extremities, resulting in dry gangrene and skin necrosis. The purpose of this article is to present a case series of skin complications related to treatment with norepinephrine and review the pathophysiology behind these complications. The authors also explore risk stratification as it relates to history and clinical presentation with subsequent focus on contingencies to mitigate the adverse effects of vasoconstriction on peripheral tissues.

A sensitive shock index for real-time patient assessment during simulated hemorrhage.

BACKGROUND: Shock index [SI = the ratio of heart rate (HR) to systolic arterial pressure (SAP)] is a metric used to diagnose patients at risk of impending hemorrhagic shock. We hypothesized that a metric called the compensatory reserve index (CRI), derived using computer modeling with continuous feature extraction from arterial waveforms, would provide an earlier indicator of cardiovascular instability than SI during progressive central hypovolemia. METHODS: There were 15 subjects (men = 8; women = 7) who underwent progressive reduction in central blood volume induced by lower body negative pressure (LBNP) until SAP < 90 mmHg. CRI was normalized on a scale of 1 (normovolemia) to 0 (circulatory volume at which instability occurs) and displayed on a colored bar. The times at which the CRI equaled 0.6 (threshold of green to amber) or 0.3 (threshold of amber to red) were compared to a clinical threshold of SI > or = 0.9. RESULTS: A SI > or = 0.9 required 22.4 +/- 6.2 min (95% CI = 19 to 25.8 min). CRI reached 0.6 (amber) at 12.5 +/- 4.9 min (95% CI = 9.8 to 15.3 min) when SI = 0.61 +/- 0.03, and became 0.3 (red) at 20.3 +/- 5.1 min (95% CI = 17.5 to 23.1 min) when SI = 0.81 +/- 1.4. CONCLUSIONS: CRI provided a significantly earlier indicator of impending hemodynamic decompensation than SI > or = 0.9 during progressive LBNP. These results support the notion that the CRI represents an improved 'shock index' as an indicator of impending hemorrhagic shock compared to standard vital signs.

Salvage of a megafistula causing high-output cardiac failure in a young adult with aneurysmorrhaphy and banding.

We present the case of a 21-year-old male with significant lengthening and aneurysmal degeneration of his brachiocephalic arteriovenous fistula resulting in a megafistula and high-output cardiac failure. A computed tomography angiogram showed narrowing at the cephalic arch. Further evaluation during the operation revealed kinking and elongation of the fistula in addition to compression of the cephalic arch in the deltopectoral groove leading to outflow obstruction. The aneurysmal fistula was treated successfully with aneurysmorrhaphy of the remaining conduit and banding of the inflow. This case demonstrates a unique etiology of venous outflow obstruction for a fistula and describes the surgical approach to its treatment in a young patient suffering from cardiac failure.

Defining the role of risk stratification and duplex ultrasound in the diagnosis of acute lower extremity deep vein thrombosis.

OBJECTIVE: Risk stratification using the plasma D-dimer level and Wells score has been proposed as a safe strategy to rule out acute lower extremity deep vein thrombosis (DVT) and limit the use of duplex ultrasound (DUS) for low-risk patients. A widely used diagnostic protocol defining the role of pretest probability and D-dimer testing in lieu of DUS has not been reported. Our aim was to define the risk of DVT in a standard population of emergency department patients who had presented with acute lower extremity symptoms and determine the role of DUS for these patients. METHODS: Outpatients presenting to the emergency department with symptoms concerning for lower extremity DVT were prospectively enrolled. All the patients underwent whole leg DUS and clinical and laboratory assessments for DVT using the Wells criteria and plasma D-dimer testing. The patients were stratified into three groups according to the combination of their Wells score and plasma D-dimer level. The prevalence of DVT and the statistical performance of the combined Wells score and plasma D-dimer were compared. RESULTS: A total of 3087 patients were enrolled. Most of the patients had had a negative plasma D-dimer level and Wells score (n = 2290 patients). A total of 222 patients had had a positive plasma D-dimer level and Wells score. The overall prevalence of acute DVT in the present study was 7.3%. Of the 2290 patients with a negative Wells score and negative plasma D-dimer level, 4 had had a diagnosis of DVT (negative predictive value, 99.8%). In contrast, DVT was present in 181 of 222 patients (81.5%) with a positive Wells score and plasma D-dimer level (positive predictive value, 81.5%). The plasma D-dimer level also correlated with the DVT location, and the D-dimer levels were highest for the patients with proximal DVT. CONCLUSIONS: The combination of a negative Wells score and negative plasma D-dimer level can safely exclude the presence of DVT. Patients with a negative Wells score and negative plasma D-dimer level are unlikely to benefit from DUS. In contrast, patients with a positive D-dimer level and positive Wells score will benefit from whole leg DUS to rule out the presence of high-risk DVT.

The clinical significance of ultra-high D-dimer levels.

OBJECTIVE: Plasma D-dimer levels >5000 ng/mL are encountered in a number of conditions other than venous thromboembolism (VTE). Recent studies have used plasma D-dimer levels as a prognostic indicator for coronavirus disease 2019 (COVID-19) infection. The implications of abnormal levels are less clear for patients diagnosed with COVID-19 with a baseline elevation in plasma D-dimer levels. In the present study, we reviewed the occurrence of plasma D-dimer levels >5000 ng/mL and investigated the clinical significance of this finding before the onset of the COVID-19 pandemic. METHODS: Inpatient records for a 4-year period were screened for laboratory results of plasma D-dimer levels >5000 ng/mL. The patient data were reviewed for the clinical identifiers commonly associated with elevated plasma D-dimer levels, including VTE, cancer, sepsis, pneumonia, other infection, bleeding, and trauma. The patients were then categorized into groups stratified by the plasma D-dimer level to allow for comparisons between the various clinical diagnoses. RESULTS: A total of 671 patients were included in the present study. VTE was the most common diagnosis for patients with a plasma D-dimer level >5000 ng/mL, followed by cancer and pneumonia. Multiple clinical diagnoses were present in 61% of the patients. No clear cause for the ultra-high plasma D-dimer level could be identified in 11.3% of the patients. Among the patients lacking a clinical diagnosis at discharge, mortality was 24% in the 5000- to 10,000-ng/mL group, 28.6% in the 10,000- to 15,000-ng/mL group, and 75% in the >15,000-ng/mL group. CONCLUSIONS: VTE, cancer, and pneumonia were frequently present when ultra-high plasma D-dimer levels were encountered, and mortality was high when the levels were >15,000 ng/mL. The results from our study from a pre-COVID-19 patient population suggest that ultra-high plasma D-dimer levels indicate the presence of severe underlying disease. This should be considered when using the plasma D-dimer level as a screening tool or prognostic indicator for COVID-19 infection.

A systematic review on the treatment of nonhealing venous ulcers following successful elimination of superficial venous reflux.

OBJECTIVE: Nonhealing leg ulcers are frequently associated with the saphenous vein reflux. Despite the success of endovascular ablations, there are patients who either fail to heal or develop recurrent ulcers. This systematic review aims to summarize the available evidence on how to treat these patients after successful elimination of superficial reflux. METHODS: A systematic review was performed following the PRISMA guidelines. The MEDLINE and Embase databases were searched for full text articles in English from 1946 to July 31, 2020. All articles that did not specifically mention the treatment of persistent venous ulcers or superficial venous reflux associated with healed or active venous ulcers were eliminated. The remaining abstracts were read for mention of either recurrent or persistent venous ulcers and, if mentioned, the full article was reviewed. All study designs were included. Study selection, data extraction and risk of bias assessment were performed by two independent reviewers. RESULTS: Four eligible studies including a total of 161 patients (177 limbs) with C6 disease were included in the review after the screening of 546 identified articles. A total of 62 patients were treated for persistent or recurrent venous ulcers after treatment of superficial reflux. Treatments included four-layer compression dressings, repeat ablations of superficial veins, and endovenous ablation of incompetent perforator veins. Overall, successful healing was noted in 50% of patients undergoing repeat ablative procedures, 100% of patients treated solely with four-layer compression dressings, and 90% of patients treated with compression and successful ablation of incompetent perforator veins. Across all studies the presence of deep vein reflux was 31% (50 of 164 limbs), post-thrombotic (secondary) ulcers 13.7% (16 of 117), and proximal obstruction was present in a single patient. Superficial venous reflux was treated using endovenous ablation (either radiofrequency ablation or laser), foam sclerotherapy, and endovenous radiofrequency ablation with or without microphlebectomy procedures. The frequency of persistent ulcers after elimination of superficial reflux ranged from 2.3% at 2 years after the intervention to 21.1% at 1 year with follow-up ranging from 6 to 52 months. CONCLUSIONS: Although further studies are warranted to improve the quality of evidence, it seems that additional ablative procedures to address incompetent perforating veins and persistent superficial reflux in combination with ongoing compression therapy is effective in healing persistent or recurrent venous ulcers after the elimination of superficial venous reflux.

Rapidly Expanding Renal Artery Aneurysm Open Repair: A Case Report.

Renal artery aneurysms are rare occurrences, representing less than 1% of all aneurysms in the general population. Little is known about the natural history and optimal management of these aneurysms. We report a 58-year-old female patient with bilateral renal artery aneurysms with significant rapid growth of the right aneurysm on 1-year follow-up. Due to her age and the anatomical complexity of the aneurysm, the patient was not a candidate for endovascular repair. She therefore underwent open repair of the right renal artery aneurysm with resection and primary anastomosis. This case offers an example of surgical management of this rare disease process.

Greater risks, fewer rights: U.S. farmworkers and pesticides.

Pesticide Action Network, United Farmworkers of America, and California Rural Legal Assistance Foundation analyzed California government data on agricultural poisonings and enforcement of worker safety standards. Nearly 500 pesticide poisonings were reported for California farmworkers every year from 1997 to 2000. The actual number of pesticide-related illnesses is unknown, since many poisonings go unreported. Most poisonings occurred as a result of soil fumigation and pesticide applications to grapes, oranges, and cotton. Pesticide drift accounted for 51% of the cases, and another 25% resulted from exposures to pesticide residues. Violations of worker safety laws were common, contributing to 41% of reported poisonings. No violations occurred in another 38%, indicating that existing laws inadequately protect workers from pesticide exposure. This snapshot of human rights abuse through pesticide exposure in California-the site of some of the world's most stringent pesticide use and worker safety laws-illustrates the global problem of pesticide poisoning among agricultural workers.

Physiologic mechanisms underlying the failure of the "shock index" as a tool for accurate assessment of patient status during progressive simulated hemorrhage.

BACKGROUND: Shock index (SI), the ratio of heart rate (HR) to systolic arterial pressure (SAP), is a metric often used to diagnose patients at risk of impending cardiovascular instability and hemorrhagic shock. We hypothesized that if SI reflected impending cardiovascular instability and shock in an individual, then: (1) elevations in SI and HR would be greater in individuals with low tolerance (LT) to progressive lower-body negative-pressure (LBNP) compared with individuals with high tolerance (HT), and (2) LT would be associated with greater vagal withdrawal of the baroreflex sensitivity (BRS) compared with HT. METHODS: A total of 187 healthy subjects (HT, 125; LT, 62) underwent exposure to LBNP until a SAP of less than 80 mm Hg (instability) was achieved. HR and SAP were used to calculate SI, and BRS was determined from spontaneous fluctuations in R-R interval and diastolic arterial pressure. Maximal cardiac vagal withdrawal was calculated as the difference between BRS at baseline and BRS at 100% LBNP tolerance. RESULTS: Contrary to our hypothesis, SI at 60%, 80%, and 100% LBNP tolerance in LT (0.59 ± 0.03, 0.73 ± 0.04, and 0.97 ± 0.06, respectively) was lower (p ≤ 0.002) than SI in HT subjects at the same levels (0.66 ± 0.03, 0.84 ± 0.04, and 1.24 ± 0.06, respectively). Maximal cardiac vagal withdrawal was less (p = 0.045) in LT subjects (11.3 ± 2.2 ms/mm Hg) compared with HT subjects (14.9 ± 2.5 ms/mm Hg). The sensitivity of SI in identifying impending instability (SI, 0.9) at 80% and 100% LBNP tolerance was 13% and 63% in LT subjects and 34% and 91% in HT subjects, respectively. CONCLUSION: The low sensitivity of the SI observed in LT individuals is associated with a lower capacity to withdraw cardiac vagal activity and can lead to an undertriage of those patients most likely to develop early hemorrhagic shock.