Theresa Jacob

Regional anesthesia: preferred technique for venodilatation in the creation of upper extremity arteriovenous fistulae.

Owing to the overall poor medical health of patients with end-stage renal disease, we have sought alternatives to the use of general anesthesia for access procedures. Furthermore, since local anesthesia (1) does not offer the motor block that is sometimes desired and (2) can be difficult to maintain when a large amount of vein needs to be transposed, we examined whether regional blocks can be useful for the creation of new arteriovenous fistulae (AVF). From August 2002 to January 2005, 41 patients scheduled for AVF placement underwent a regional block with the use of a lidocaine and ropivacaine mixture using a nerve stimulator. Either axillary, interscalene, or infraclavicular blocks or a combination was used. Intraoperative duplex ultrasonography was used to assess the degree of venodilatation of the basilic and cephalic veins before and after the block. The site of each measurement was marked on the skin and selected by a clearly identifiable branch point. Each measurement was recorded three times and was made in the (1) native state, (2) after application of a tourniquet with opening and closing of the hand for 15 seconds, and (3) after placement of the block. The average age of the patients was 65 ± 14 years (SD), with ages ranging from 33 to 91 years, and the prevalence of diabetes mellitus was 50%. Complete brachial plexus block was achieved in 34 patients (83%). Sensory block was accomplished within 10 to 15 minutes and usually lasted 4 to 6 hours. Motor block was accomplished in 10 to 25 minutes. Venodilatation was not noted in patients whose blocks did not work (n = 7) or whose vein was found to be phlebitic on exploration (n = 3). The degree of venodilatation noted as a percentage increase after application of the tourniquet compared with the native state for these 34 patients (in whom the block worked) was 37% for the distal cephalic, 31% for the midcephalic, and 32% for the midbasilic vein. The degree of venodilatation noted as a percentage increase after placement of the block compared with after tourniquet application for these 34 patients was 42% for the distal cephalic, 19% for the midcephalic, and 26% for the midbasilic vein. No instances of systemic toxicity, hematomas, or nerve injury from the block were noted. Accesses placed included 20 radiocephalic AVF, 8 brachiobasilic AVF, 8 brachiocephalic AVF, 2 arteriovenous grafts, 2 radiobasilic AVF, and 1 brachial vein AVF. Regional block is a safe and, in our opinion, preferred technique for providing anesthesia for upper extremity vascular surgery. The venodilatation observed is augmented compared with that using a tourniquet and may allow more options for access placements.

Glycine prevents the induction of apoptosis attributed to mesenteric ischemia/reperfusion injury in a rat model.

PURPOSE We have previously demonstrated that glycine has a protective effect in mesenteric ischemia/reperfusion (I/R) injury. The purpose of this study was to elucidate the molecular mechanisms of the cytoprotective action of glycine. Because oxidative stress in I/R injury can lead to apoptosis, we examined the role of glycine in modulating the apoptotic signals in a rat mesenteric I/R injury model. METHODS Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals (n=6) received normal saline intravenously at the rate of 0.01 mL/g/h during the ischemia and reperfusion period. Treated animals divided in 3 groups (n=6 in each) received glycine at a dose of either 0.5, 0.75, or 1.0 mg/g, infused at the rate of 0.01 mL/g/h during the reperfusion period. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were harvested for histopathology, TUNEL assay, and immunohistochemistry. Expression of apoptosis-related molecules, bcl-2, bax, caspase-3, death receptor, Fas, and death substrate, poly (ADP-ribose) polymerase (PARP) were studied. RESULTS In glycine-treated animals, the middle and distal segments of the small intestine were well- preserved and showed better histologic grade and morphometric parameters as compared with saline controls (P<.05) in a dose-independent manner. There was increased apoptosis in saline controls as compared to the treated group (P<.01). Pro-apoptotic bax and caspase-3 were downregulated, whereas bcl-2 was upregulated in the glycine-treated animals (P<.02). Increased expression of death receptors and cleavage of PARP was observed in saline controls as compared to treated groups (P<.05). No significant differences were noted between the proximal bowel segments of treated and control animals. CONCLUSIONS These data support the concept that I/R causes formation of death- inducing signal complexes, which may activate the sequential cleavage of caspases and death substrates. We have demonstrated that one of the mechanisms of the protective effect of glycine is the downregulation of the death-inducing signals and abrogation of the apoptotic cascade in this I/R injury model.

Prospective randomized study comparing the clinical outcomes between inferior vena cava Greenfield and TrapEase filters

OBJECTIVE Although anticoagulation remains the mainstay of treatment for deep venous thrombosis, the use of inferior vena cava (IVC) filters when anticoagulation has failed or when contraindicated remains a safe and effective treatment. Greenfield (Boston Scientific, Natick, Mass) and TrapEase (Cordis, Bridgewater, NJ) filters are arguably among the most popular filtration devices. The Greenfield filter (12F introducer) has been in use for >30 years and has been well studied. The TrapEase filter (6F introducer) has been used since 2000, with a limited number of studies. Good guidelines to help determine which filter to use in any given situation are lacking; therefore, this randomized study prospectively compared the clinical outcomes (access-site thrombosis, filter thrombosis, and symptomatic pulmonary embolism [PE]) between these filters. METHODS Between July 2006 and November 2008, 156 patients (63 men, 93 women; mean age, 75 years; range, 38-101 years) were randomized: 84 to Greenfield and 72 to TrapEase IVC filter insertion in the infrarenal position using angiographic guidance. Postoperative follow-up comprised serial lower extremity and IVC/iliac vein (IV) duplex imaging (78.2%) at day 1, week 1, every 3 months for the first year, and every 6 months for the second year; clinical evaluation, and clinic visits. During this period, 349 patients (143 men, 206 women; mean age, 75 years; range, 24-96 years) were not randomized. RESULT The indications for filter placement, in the 156 randomized patients, were gastrointestinal bleeding, 37; intracranial hemorrhage, 12; free-floating clot, 19; failure of anticoagulation, 29; PE, 27; prophylactic, 4; and others, 32. During a mean 12-month follow-up (range, 0-39 months), symptomatic IVC/IV thrombosis developed in five patients (6.94%) in the TrapEase group and none in the Greenfield group (P = .019). No filter migration, access-site thrombosis, misplacement, or IVC perforation occurred. Recurrent PE was suspected in one of the five patients with IVC/IV thrombosis. Overall mortality was 42.3% (66 patients), and 30-day mortality was 13.5% (21 patients: 10 TrapEase, 11 Greenfield). The study was initially designed to recruit 360 patients in both TrapEase and Greenfield filters in 2 years to demonstrate any statistical significance but was prematurely concluded due to the interim results. CONCLUSION A higher rate of symptomatic IVC/IV thrombosis is associated with TrapEase filter placement. However, the TrapEase filter still has a selective clinical role in the prevention of thromboembolism in selected patients who are coagulopathic. This is the first randomized prospective study comparing IVC filters since their inception in 1967.

Morbidity and Mortality Associated with the Utilization of Restraints

Use of physical restraints remains a highly controversial topic. Even with proven efficacy in restraint usage across multiple settings, for years, investigators have debated whether or not the risks outweigh the benefits. There is a growing concern regarding restraints-related negative consequences. Although over the past two decades, with new regulations, education and training, there has been a reduction in the prevalence of restraint episodes, morbidity and mortality are still disconcerting. Given this subject remains an issue today, a more up-to-date review of available literature is warranted. This article reviews the current literature surrounding the utilization of restraints that has been published over last 10 years with particular emphasis on restraints-related adverse outcomes. The vast amount of literature during the past decade demonstrates an increased awareness in potential dangers, as well as highlights new areas of research in restraint utilization. Despite the proliferation of studies, there continues to remain a lack of evidence from prospective studies that would elucidate the dangers from theory to practice.

P53 gene transfer to the injured rat carotid artery promotes apoptosis

BACKGROUND In a previous study we have demonstrated significant reduction of intimal hyperplasia after adenovirus-mediated gene transfer of p53 protein to the injured rat carotid artery. The purpose of this study was to elucidate whether apoptosis is one of the mechanisms responsible for this reduction. Apoptosis, a physiologic cell death process that stabilizes cell numbers in tissues, can be independently induced by p53. METHODS In vivo gene transfer was used in isolated segments of balloon-injured rat carotid arteries. Genetically modified adenovirus encoding for wild-type p53 protein (AdWTp53) was applied at 8 x 10(10) plaque-forming units/mL. Control rats received either adenovirus null at the same concentration or balloon injury alone. Arteries were harvested at 24 and 48 hours after the procedure. Apoptosis was detected in tissue sections by in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Specimens were graded either negative or positive less than 10%, 10% to 20%, 20% to 30%, or greater than 30% according to the number of apoptotic cells in the medial or intimal layer per high power field. Specimens were also subjected to DNA agarose gel electrophoresis and transmission electron microscopy. RESULTS With the TUNEL assay no apoptosis was visualized at 24 and 48 hours in the controls (n = 5 in each group), whereas in the AdWTp53 groups (n = 5 in each) all specimens presented apoptosis (P < .05, AdWTp53 vs controls). The average grade of apoptotic cells detected in the medial layer in the AdWTp53 groups was less than 10% to 20% at 24 hours and 20% to 30% at 48 hours. The DNA agarose gel electrophoresis failed to detect a DNA laddering pattern, characteristic of apoptosis. Electron microscopy revealed morphologic changes typical of apoptosis in the treated group, whereas specimens from control group did not reveal any apoptotic features. CONCLUSIONS At 48 hours after balloon injury alone, no apoptosis was observed in the vessel wall. However, when p53 gene was transferred, apoptosis was visualized in all specimens with greater intensity at 48 hours after injury. Promotion of apoptosis may play a key role in the mechanism by which p53 gene decreases intimal hyperplasia.

Limitations of and Lessons Learned from Clinical Experience of 1,020 Duplex Arteriography

Objective: Due to the inherent risks, deficiencies and cost associated with contrast arteriography (CA), our group has been utitilizing duplex arteriography (DA) for evaluating the arteries of the lower extremity for patients undergoing lower extremity revascularization. In an effort to further explore the strengths and weaknesses of DA, we reviewed our evolving experience with DA from January 1, 1998, to January 1, 2005. Patients and Methods: The arterial segments starting from mid-abdominal aorta to the pedal arteries were studied in cross-sectional and longitudinal planes using a variety of scanheads of 7–4, 10–5, 12–5, 5–2 and 3–2 MHz extended operative frequency range to obtain high-quality B-mode, color and power Doppler images as well as velocity spectra. In 906 patients, 1,020 duplex arteriograms were obtained. The ages ranged from 30–98 years old with a mean of 73±11 (SD) years. Fifty percent of the patients were diabetics. Indications for the examination included: tissue loss (409), rest pain (221), claudication (310), acute ischemia (74), popliteal aneurysm (45), SFA aneurysm (2), abdominal aortic aneurysms (AAA) (10) and failing bypass (55). Prior procedures had been performed in 262. DA was performed by six technologists (4 of whom are MDs). In all, 207 DA were performed intraoperatively and the remainder, preoperatively. Results: The resultant procedures based upon DA included: bypass to the popliteal artery (262) and bypass to an infrapopliteal artery (325), endovascular procedures (363), thrombectomy (11), embolectomy (9), inflow bypass procedures to the femoral arteries (46), débridment (4), amputation (8) and no intervention (75). The areas not visualized well included: iliac (73), femoral (26), popliteal (17), and infrapopliteal (221). Additional imaging after DA was deemed necessary in 102 cases to obtain enough information to plan lower extremity revascularization. Factors associated with increased need to obtain CA included: DM (p<.001), infrapopliteal calcification (p<.001), older age (p = .01) and limb threatening ischemia (p<.001). Factors not associated with the need to obtain CA included: which technologist performed the exam, whether the technologist has a medical degree and whether the patient underwent prior revascularization. Conclusions: In 90% of patients reviewed, DA is able to obtain the needed information to plan lower extremity revascularization. Severe tibial vessel calcification is the most common cause of an incomplete DA exam and determines when alternative imaging modalities need to be obtained.

Clinical experience with superior vena caval Greenfield filters.

Purpose: To evaluate the results of superior vena caval (SVC) Greenfield filters in patients at risk for pulmonary embolism (PE) secondary to upper extremity deep venous thrombosis (UEDVT). Methods: Over a 46-month period, 26 patients (10 men, mean age 67 years, range 25 to 89) with UEDVT in whom anticoagulation was contraindicated (n = 22) or ineffective in preventing recurrent PE or extension of the thrombus (n = 4) were treated with placement of SVC Greenfield filters. Results: One SVC filter was misplaced into the innominate vein but left in place; this vein remains patent after 2 months without evidence of filter migration. Follow-up ranged from 10 days to 46 months (mean 7.8 months). Fifteen (58%) patients died inhospital of causes unrelated to the SVC filter or recurrent thromboembolism (mean time to death 36 days). Of the 11 survivors, follow-up ranged from 1 to 38 months (mean 22). Sequential chest roentgenograms in 9 (82%) patients revealed no filter migration or displacement. No evidence of PE was found in any of the survivors over the course of follow-up. Conclusions: Insertion of SVC Greenfield filters is a safe and feasible therapy to prevent recurrent thromboembolism in patients with UEDVT who are refractory to or inappropriate for anticoagulation therapy.

Pulmonary Embolism Without Deep Venous Thrombosis

BACKGROUND To identify patients with pulmonary embolism (PE) without deep venous thrombosis (DVT), and to compare them with those with an identifiable source on upper (UED) and lower-extremity venous duplex scans (LED). METHODS We performed a retrospective review of 2700 computed tomography angiograms of the chest between January 2008 and September 2010 and identified 230 patients with PE. We then evaluated the results of UED and LED and divided the patients into four groups based on the results of their duplex studies. We compared patients with PE and DVT with those with PE and no DVT in terms of age, gender, size and location of PE, critical illness, malignancy, and in-hospital mortality. RESULTS We identified 152 women and 78 men (mean age, 68 years) with PE. One hundred thirty-one patients had a documented source of PE (group 1). Fifty-three patients had negative LED results, but did not undergo UED (group 2). Thirty-one patients did not undergo either LED or UED (group 3). Seven men and eight women had no documented source of PE on UED and LED (group 4). Ten of 15 patients in group 4 had a documented malignancy listed as one of their diagnoses. Because patients in groups 2 and 3 did not undergo complete duplex studies, we excluded them from our analysis. We then reviewed the discharge summaries of patients in groups 1 and 4. There was no statistically significant difference in age and gender distribution, size and location of PE, critical illness, smoking status, cardiovascular disease, trauma, and in-hospital mortality between patients in group 1 and 4. Patients in group 4 had a statistically significant increased prevalence of malignancy (67% vs. 40%, P = 0.046). Patients in group 4 also had a higher percentage of active cancer than those in group 1 (47% vs. 24%, P = 0.084), although not statistically significant. We defined active cancer as either a metastatic disease or a malignancy diagnosed shortly before or after the diagnosis of PE. Patients who were undergoing treatment for cancer at the time of diagnosis of PE were also considered to have active cancer. CONCLUSION We demonstrated a statistically significant increased prevalence of malignancy in patients with PE without DVT. However, pathophysiology and clinical significance are the aspects that remain to be understood after accrual of more patients and further research. Possibilities such as de novo thrombosis of pulmonary arteries, complete dislodgement of thrombi from peripheral veins, or false-negative venous duplex need to be explored.

Protective effect of glycine in mesenteric ischemia and reperfusion injury in a rat model

PURPOSE Glycine has a protective effect in renal and skeletal muscle ischemia. The purpose of this study was to evaluate the effect of glycine in mesenteric ischemia and reperfusion injury in a rat model. METHODS Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals received normal saline solution intravenously at 0.01 mL/g of body weight/h during ischemia and reperfusion. Treated animals received glycine at 0.5, 0.75, or 1.0 mg/g of body weight, dissolved in saline solution and infused at 0.01 mL/g/h for 2 hours. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were isolated. Sections of the segments stained with hematoxylin-eosin were subjected to histologic examination (as per modified Chiu grading system) and morphometric analysis consisting of measurement of bowel wall, muscularis and mucosal thickness, epithelial coverage, and villar circumference. Isometric tension responses to electrical stimulation (10, 30, 50, 100 Hz), high doses of potassium (120 mmol/L), and carbachol (0.1, 0.5, 1.0, 5.0 micromol/L) were recorded in a multimuscle chamber. Statistical analysis was performed with unpaired t test and one-way analysis of variance. RESULTS The middle and distal segments of the small bowel in glycine-treated animals showed better histologic grade compared with saline solution-treated control rats (P <.05). At morphometric analysis, total thickness, mucosal thickness, and villar circumference ratio were well preserved in the middle and distal segments of the small bowel in the glycine-treated group (P <.05). No significant differences were observed in the proximal bowel segments between glycine-treated and control animals, because the proximal segment was not subjected to much ischemia. No differences were noted in percentage of epithelial coverage. Isometric tension responses evoked by electrical stimulation were greater (P <.05) in the middle and distal segments treated with glycine as compared with control segments. Carbachol-evoked contractions were stronger (P <.05) in the small bowel segments of animals treated with glycine. The responses evoked by 120 mmol/L of potassium were stronger in the distal segments of the small bowel in the glycine-treated group (P <.05). This cytoprotective effect of glycine was not dose-dependent. CONCLUSIONS Glycine improved mucosal viability in the ischemia and reperfusion injury rat model. Mucosal thickness and villous circumference ratio were reliable objective parameters for evaluation of intestinal ischemia injury. Glycine improved the contractile responses of the bowel segments also, probably by altering the physiologic mechanisms underlying force generation. Further studies are required to elucidate the mechanism of the cytoprotective action of glycine.

Early transposition of the sartorius muscle for exposed patent infrainguinal bypass grafts.

The traditional approach for patent and exposed and infected infrainguinal bypass grafts in the groin has included wide operative debridement and secondary or delayed primary closure. However, this has been associated with significant risk of further contamination and length of stay. The authors reviewed their experience using the wide debridement, sartorius muscle flap transposition, and primary wound closure as an alternative. During the past 5 years, they have had 50 patients with major wound necrosis or infection in the groin or thigh with the graft or native artery being exposed after debridement. This group included 28 men; 74% of the patients had hypertension, 58% had diabetes, and 20% had renal failure. The grafts were split evenly between native vein and prosthetic material. After wide debridement, closure was performed by the vascular surgeon using the sartorius muscle flap. Postoperatively, there was an 8% major amputation rate and a 12% mortality rate in the first 30 days. One patient developed a pseudoaneurysm 5 weeks after placement of the flap. This patient underwent removal of the infected polytetrafluoroethylene graft with ligation of the common femoral artery. None of the procedures have resulted in further systemic or graft sepsis. None have resulted in arterial or graft blowout. Follow-up was for an average of 18 months. Closure of groin and thigh wounds with exposed bypass graft or native artery can be safely performed with the sartorius muscle flap with excellent results. The length of stay of these patients compared to historical controls is acceptable. Furthermore, the chance of infection of the native artery or bypass may be reduced. Familiarity with this simple technique can be a valuable tool for the vascular surgeon.