Independent association of arteriovenous ratio index on the primary functional maturation of autologous radiocephalic arteriovenous fistula.

OBJECTIVE: It has been hypothesized that a novel measurement technique of arteriovenous ratio (AVR) index obtained from inflow (radial artery diameter) to that of outflow (cephalic vein diameter) and its application through the Bernoulli effect has no impact on the primary functional maturation (FM) of autogenous radiocephalic arteriovenous fistula (RCAVF). METHODS: A prospective consecutive single-center cohort study with intention to treat of 324 patients undergoing RCAVF during a period of 4 years was conducted. Variables of demographics, anatomic factors, laterality, comorbidities, anesthesia type, presence of intraoperative thrill, angle of anastomosis, and AVR index were assessed through univariate and multivariate logistic regression analysis on the end point of FM. The AVR was subjected to three decimal points to ensure maximal accuracy for best sensitivity and 1 - specificity by receiver operating characteristic curve. The χ2 (subgroup) analyses were undertaken to investigate the differences in FM incidence within different ranges of AVR. Test of probability (P value) was considered to be significant with P < .05. Effect sizes were reported as odds ratio with their measure of uncertainty at 95% confidence intervals. RESULTS: Among all variables, the AVR index remained the only independent factor associated with FM (66%; n = 214/324) of RCAVFs (P = .001; 95% confidence interval, 0.08-0.26). AVR of 1 to 1.06 was associated with 100% FM in RCAVFs. Decrease or increase of this index was associated with stepwise reduction in FM of RCAVFs (P < .05). CONCLUSIONS: The suggested novel measurement technique (AVR index) is an independent predictor of FM in RCAVFs. This study implies that minimal diameter (ie, inflow artery dimeter to outflow cephalic vein diameter) mismatch (AVR, 1-1.06) irrespective of other variables remains crucial for optimal hemodynamics (pressure and velocity) of RACVFs and their primary FM.

The independent association of preoperative serum albumin on the functional maturation of radiocephalic arteriovenous fistulae.

PURPOSE: The aim of this study is to test the null hypothesis that preoperative albumin along with other preoperative confounders have no impact on the functional maturation of radiocephalic arteriovenous fistulae (RCAVF). METHODS: A retrospective cohort study of n = 195 individuals undergoing RCAVF formation from July 2013 to December 2015 was conducted. The null hypothesis was assessed through chi squared test. Independent association of each variable was evaluated through univariate and multivariate logistic regression model. Pearson's correlation test was also performed between scale variables to establish their causal link. RESULTS: Preoperative hypoalbuminaemic group of individuals demonstrated significant failure of maturation (49.3% vs. 27.2%, p = 0.002). At multivariate analysis, hypoalbuminemia remained an independent marker of fistula failure (OR 0.40, 95% CI 0.21-0.76, p = 0.004) and demonstrated a weak but a positive correlation at the endpoint of maturation (R = 0.223, p = 0.002). CONCLUSIONS: Preoperative hypoalbuminemia (<35 mg/dL) is independently associated with 40% reduction in the functional maturation of RCAVF. Stratification of this readily available biomarker prior to RCAVF formation may require consideration subjected to further research.

The Clinical Implication of Blood Product Transfusion on Morbidity and Mortality of Ruptured Abdominal Aortic Aneurysm.

BACKGROUND: Transfusion of blood products occurs frequently in ruptured abdominal aortic aneurysm surgery (rAAA). The aim of this study is to establish the impact of packed red blood cell (PRBC), fresh frozen plasma (FFP), and platelet (PLT) transfusion on the 30-day mortality and morbidity (thrombotic versus non thrombotic complications) of rAAAs. METHODS: A retrospective study of 90 consecutive rAAAs from November 2007 to June 2015 was conducted. Multivariable regression models were produced to determine blood products associated with 30-day morbidity and mortality post-rAAA. RESULTS: The overall mortality was 14.6%. At multivariable analyses, transfusion with FFP (>3 units) was independently associated with an increased risk of mortality (odds ratio [OR]: 11.27, 95% confidence interval [CI]: 1.13-96.72, P = .027). The overall morbidity was 26.8%, and subgroup analysis (thrombotic vs nonthrombotic complications) demonstrated transfusion of PLTs (>1 pool) to be independently associated with thrombotic events (OR: 4.3, 95% CI: 1.37-13.6, P = .012). Thrombotic events were responsible for 50% (n = 11 of 22) of all morbidities and mortalities (n = 6 of 12). CONCLUSION: Transfusion of FFP and PLTs may be associated with an increased risk of postoperative morbidity and mortality. The use of these blood components should be considered in the context of the patient's clinical and laboratory data as opposed to a fixed ratio to PRBCs. This may result in the reduction in thrombotic complications emerging in rAAA cohort.

Validation of the Guy's scoring system in patient selection for femoro-distal bypass grafting to a single calf or pedal artery.

OBJECTIVES: First external validation of a preoperative scoring system (Guy's) in patient selection for femoro-distal bypass grafting to single calf or pedal artery in critical limb ischemia (Fontaine III & IV/Rutherford grade IV, V & VI). MATERIAL AND METHODS: A prospective study of 76 (n = 76) consecutive femoro-crural/pedal bypass grafts on 72 individuals (n = 72) from 2008 to 2011 with 36 months mean follow-up was performed. All cases were scored against a previously designed and published scoring system (ranging from 0 to 10) based on: inflow, outflow, graft material, flow type, patent pedal vessels and diabetes mellitus. RESULTS: Preoperative score of 0-4 (n = 37) demonstrated the primary patency of 27% at 10.3 months. This value for intermediate group 5-7 (n = 34) was 70.6% at 18.9 months. The high-score group 8-10 (n = 4) showed the longest primary patency (80%) at 27.3 months. Kaplan-Meier survival analysis exhibited a consistent and significant difference in primary assisted, secondary patency and overall limb/foot salvage amongst all individual scoring groups (p < 0.001). CONCLUSION: This study validates and complements the Guy's scoring system and provides a platform for the identification of critical limb ischemia patients in whom the result of femoro-crural/distal bypass grafting is so poor that primary amputation may be both clinically and economically more justified.

Cephalic vein and radial artery diameter in formation of radiocephalic arteriovenous fistula: a systematic review.

PURPOSE: The aim of this study is to determine the optimal range of cephalic vein and radial artery diameter following preoperative duplex imaging to enhance maturation and primary patency of Brescia-Cimino radiocephalic arteriovenous fistula. METHODS: A systematic review and meta-aggregation of literature from 1966 to January 2015 in English language and adult subjects in Pubmed, OVID, CINHAL and Cochrane database was conducted. RESULTS: This search produced a total of thirty-six (n = 36) articles. Following the application of recruitment criteria, only twelve articles (n = 12) were found eligible. Their quality was assessed by Oxford Critical Appraisal skills Programme (CASP) and their recommendation for practice was examined through National Institute for Health and Care Excellence (NICE). CONCLUSIONS: The current literature suggests that the optimal range of radial artery for maximum performance (maturation and primary patency) of RCAVF is at least 2 mm (level 2, grade a). The cephalic vein diameter of at least 2 mm (non-augmented) can result in best maturation and primary patency outcomes (level 2, grade a) and threshold below 1.5 mm is not advocated (level 2, grade b).

Volume blood flow, static pressure ratio and venous conductance in native arterio-venous fistulae: three surveillance methods compared.

PURPOSE: Dialysis venous pressure monitoring has been widely recommended as a surveillance method but has not been shown to improve access outcomes in randomised controlled trials. The method has been impaired by the need to either turn off the blood pump or to derive the static venous pressure from the venous pressure measured with the dialysis pump running. We have developed a unique algorithm which converts Doppler-shifted spectral information derived from unscaled pulsatile blood flow waveforms into an estimate of mean blood pressure (MBP) at the point of ultrasound insonation. METHODS: We have devised the unique expression shown here: MBP = MAP/(1 + Pff/Vff) where MAP is the mean arterial pressure, Pff = (systolic - diastolic)/MAP measured on the contralateral arm and Vff = spectral maximum - minimum/mean. Venous conductance (VC) can be measured by combining this pressure data with Duplex ultrasound blood flow data. A new device BlueDop™ has been used to illustrate the potential clinical value of non-invasive static pressure ratio (SPRn) in a monitoring role. Duplex and BlueDop™ technology were tested in an arterio-venous fistula (AVF) study in which VC, Q and SPRn were compared. Thresholds used for detection of ≥60% venous stenosis were VC <10 mL min-1 mm Hg-1, Q <500 mL min-1, SPRn >0.56. RESULTS: The following accuracy was achieved: VC = 96%, Q = 92%, SPRn = 76% with similar accuracy in predicting premature thrombosis. CONCLUSIONS: A new algorithm has been described and its in vivo accuracy in estimating mean 'pressure from flow' has been confirmed. Two new variables and a new dedicated instrument BlueDop™ have been demonstrated in clinical use.

Neutrophil to lymphocyte ratio (NLR) of five predicts 30-day morbidity in ruptured abdominal aortic aneurysms (rAAA): a retrospective cohort study.

BACKGROUND: In recent years the role of neutrophil to lymphocyte ratio (NLR) as an independent predictor of mortality and morbidity has gained significant attention in colorectal, upper gastrointestinal and cancer surgery. To date, no study has examined this in ruptured abdominal aortic aneurysms (rAAAs). This study aims to assess the role of NLR as a prognostic marker of 30-day (30d) morbidity and mortality in patients undergoing repair of rAAAs. METHODS: Data from 80 consecutive patients with a diagnosis of rAAAs from November 2007 to June 2014 were included. Receiver operating characteristic curve analysis was used to identify the optimal value for NLR in relation to 30d mortality and morbidity. Univariate and multivariate logistic regression analysis were used to determine the role of NLR after stratification by several clinical factors. RESULTS: 25 patients (31.2%) had a low NLR (LNLR) and 55 patients (68.8%) had a high NLR (HNLR). Elevated NLR was significantly associated with low Hemoglobin and it was not associated with gender, age, AAA Size, history of HTN, COPD, smoking and renal failure. Patients with HNLR had higher 30d morbidity compared with the LNLR group (35 vs. 6 p = 0.001) but no difference in intraoperative blood loss, length of hospital, ITU stay and 30d mortality. High NLR through multivariate analysis was an independent prognostic factor for 30d morbidity [OR = 4.28, 95% (1.27-14.42), p = 0.02]. CONCLUSION: A preoperative NLR >5 is an independent predictive marker of 30d morbidity in rAAAs. This appears to be in line with earlier literature demonstrating similar outcome in the elective group of abdominal aortic aneurysm.

Donor artery aneurysm formation following the ligation of haemodialysis arteriovenous fistula: a systematic review and case reports.

PURPOSE: The purpose of this study is to investigate the pathogenesis, presentation and diagnosis of donor artery aneurysm formation following arteriovenous fistula (AVF) ligation and reach a consensus on their management. METHODS: A systematic review of literature in Ovid, MedLine, Embase, Scopus and CINHAL in the English language from 1951 to 2014 was performed. This was accompanied by two case reports. A total of 12 articles with 23 case reports were identified. Variables including patient's demographics, signs, symptoms, fistula type, duration of fistula use, time to aneurysm formation, renal transplantation, diagnostic modality, aneurysm type and size, type of surgery and outcome were reviewed. RESULTS: The data demonstrate a male predominance (5:1) and a median age of 47 years (range, 27-75 years). The median duration of access was 54 months (range, 6-300 months). The median time from ligation to aneurysm was 120 months (range, 6-280 months). The commonest aneurysm was of the brachial artery (BA, n = 21, 84%). The commonest type of AVF was radiocephalic (n = 15, 60%) followed by brachiocephalic AVF (n = 9, 36%). The management of choice was aneurysmectomy followed by interposition vein grafting (n = 12, 50%) with a median reported patency of 12 months (range, 1-38 months). This was followed by polytetrafluoroethylene (PTFE) grafting (n = 6, 25%) with a median reported patency of 6 months (range, 1-48 months). CONCLUSIONS: The pathogenesis of donor artery aneurysms remains contentious. This review suggests that duplex is the investigative modality of choice and aneurysmectomy with interposition grafting is preferred over bypass.

Aneurysmal degeneration and type Ib endoleak with proximal aneurysm rupture: A case report, review of literature and technical suggestions.

INTRODUCTION: Despite the reduction in mortality incidences of AAA in proportion to increased use of EVAR, the natural history of aneurysms with the presence of an endoleak post EVAR remains unclear. With a cumulative AAA rupture incidence of 2% at six years post EVAR, the lack of an immediate endoleak is not an indicator of success. CASE REPORT: We present a case of an 80-year-old man who presented to the emergency department with generalised abdominal pain and hypotension. Four years earlier he had underwent an EVAR for a 6 cm infra-renal AAA. The computed tomography angiogram (CTA) illustrated aneurysmal dilatation of the left common iliac artery with extensive retroperitoneal haemorrhage. The patient was transferred to the operating room for an endovascular repair but due to significant episodes of haemodynamic instability, an emergency exploratory laparotomy was performed. To our surprise, there was a left-sided infra-renal anterolateral rupture of the aneurysm sac. The stent was explanted with difficulty from its fixed proximal aortic section down to left-sided common iliac artery. The fixed bare portion of the stent in the proximal aorta and in the right common iliac artery was left in-situ and the rest was integrated to a trouser graft with an end-to-end technique. DISCUSSION: On detection of an endoleak, the aim should focus on their endovascular management, as open conversions are associated with high mortality and morbidity. CONCLUSION: If open conversion is indicated, all technical aspects of the repair including partial stent extraction should be considered for best outcome.

Efficacy of normal saline in the maintenance of the arterial lines in comparison to heparin flush: a comprehensive review of the literature.

PURPOSE: The aim of this study is to examine the efficacy of normal saline (0.9% sodium chloride) as a flush solution on patency of arterial lines in comparison to heparin flush. Data have been examined in various categories of specialty (medical, surgical, cardiac, burns, gynecology), frequency of flushes, strength and volume of flushes, continuous versus bolus, duration of each flush and patency incidence (range, ≤ 24 to ≥ 96 hours). The secondary aim focused on the incidences of reported heparin-induced thrombocytopenia (HIT type I and II). METHODS: A comprehensive review of the literature from 1951 to 2012. An electronic search of OVID, Medline, Embase, Cochrane, Scopus and CINAHL database in English language was conducted. The search was limited to adult subjects only. The following keywords were used: heparin flush, saline flush, 0.9% sodium chloride flush, arterial line and indwelling vascular line. A total of ten papers (n=10) were found eligible. RESULTS: The evidence suggests patency is feasible with both solutions but if longer duration of use (arterial line) is advocated, heparin is superior in the long term. Furthermore, heparin flush effects are dose dependent and require fewer numbers of flushes. In addition, no adverse effects were found with heparin flush solution. CONCLUSION: There is level 1 evidence to support heparin as a flush solution once the time frame exceeds 48 hours. In addition, there is level 1 evidence to suggest that heparin at higher doses and in continuous infusion has better patency incidence with no reports of HIT type II or I.

Ruptured cryptogenic mycotic abdominal aortic aneurysm by Salmonella enteritidis.

BACKGROUND: The aim of this study is to describe a case of ruptured cryptogenic mycotic abdominal aortic aneurysm by Salmonella enteritidis (SE) and present a comprehensive review of the literature. METHODS: A 66-year-old man with a past medical history of coronary artery bypass graft (CABG) and polymylagia rheumatica (PMR) presented with a 2-day history of right-flank-to-groin pain and fever. He was found to have tenderness on the right of the umbilical region and laboratory data showed leukocytosis, raised C-reactive protein, and a significant drop in hemoglobin level as compared with his first visit 17 days earlier, with no hemodynamic instability. An immediate computed tomography angiogram (CTA) was performed, which showed a 4-cm, fusiform, ruptured infrarenal aortic aneurysm. Exploratory laparatomy was performed and the aorta was isolated and excised from the infrarenal level to the common iliac bificuration. A straight silver Dacron graft soaked in rifampicin was placed with an end-to-end anastomosis. The excised aorta and the lymph nodes were sent for histologic and microbiologic assessment. RESULTS: Blood culture and specimen microbiology grew Salmonella enteritidis (SE). The histology exhibited atherosclerosis at the rupture point with decreasing neutrophil deposition from the intima to the adventitia layer, respectively. CONCLUSIONS: Infrarenal abdominal mycotic aneurysm (MA) by SE was observed and showed vague, nonspecific signs and symptoms. We recommend a high index of suspicion and low threshold for use of CT imaging in any infected patient of age >60 years with fever and abdominal pain on a background of diabetes and connective tissue disease. A comprehensive review of the literature was performed due to a lack of consensus on the best surgical treatment and limited information on the path of SE-induced aortitis or MA from presentation to final outcome.

Atmospheric pressure and infra-renal abdominal aortic aneurysm rupture: a single observational study and a comprehensive review of literature.

INTRODUCTION: There have been various suggestions that abdominal aortic aneurysm rupture (rAAA) might have a seasonal variation depending on atmospheric pressure (AP) alteration. Despite above suggestions no study has yet examined the effect of fluctuation in AP on daily, seasonal, monthly, AAA size and co-morbidities to reach a conclusive outcome. METHODS: A total of fifty (n = 50) ruptured AAA over a 5-year period were retrospectively studied. Local meteorological data on AP were obtained from UK Meteorological Office. The data was subjected to statistical analysis using Student's t-test, linear regression (Pearson correlation Coefficient) and Coefficient of determination to establish any casual link between AP and incidences of rAAA on daily, seasonal and monthly basis. The casual link was also assessed between AP, AAA size and co-morbidities. The outcome is presented in a format of comprehensive review of literature that detected only 6 papers in MEDLINE and EMBASE from 1951 to 2012 in UK. CONCLUSION: There appears to be a significant correlation between mean monthly pressures and mean monthly rupture incidence (Pearson)(n = 12; r = -0.61; p < 0.034; rsq = 0.37). The periods of low AP are associated with higher incidence of rupture (rAAA n = 29 at mean atmospheric pressure 1012 mB Vs rAAA n = 12 at mean atmospheric pressure 1016 mB Vs rAAA n = 9 at mean atmospheric pressure of 1020 mB) in our study and all reviewed literature. In addition, no casual link between AP to co-morbidities (diabetes mellitus, hypertension ischaemic heart disease, chronic obstructive pulmonary disease) and AAA size could be established or found in the literature.

Subtle mesenteric avulsion in a traumatic abdominal wall hernia: A case report.

INTRODUCTION: Traumatic abdominal wall hernias (TAWHs) are uncommon and to date less than 50 cases have been reported in the literature. Furthermore mesenteric avulsion is a rare complication of TAWHs and occurs in less than 5% of all cases. PRESENTATION OF CASE: A 47-year-old lady presented to the emergency department after a road traffic accident. In spite of seat belt use and airbag deployment, the patient presented with a visible left paramedian abdominal mass, which was tender and irreducible on examination. Subsequent computed tomography (CT) of the abdomen confirmed herniation of the small bowel with no free air or fluid in an otherwise stable patient. Intra-operative findings confirmed mesenteric avulsion and bowel necrosis. DISCUSSION: The role of emergency or elective repair of TAWHs remains unclear. As 58% of blunt mesenteric and bowel injuries due to avulsion are missed on initial work-up, it is advisable for clinicians to balance the risk of unnecessary and non-therapeutic emergency laparotomy with the morbidity and mortality associated with delay in diagnosis. CONCLUSION: Mesenteric avulsion in TAWH is rare and difficult to diagnose and a high index of suspicion is warranted despite normal findings on initial assessments.

Balloon control of the saphenofemoral junction during foam sclerotherapy: proposed innovation.

Venous obliteration using foam sclerosant is a relatively new procedure that holds great promise and may prove to be as effective as conventional surgical treatments in obliteration of the great saphenous vein. Foam sclerotherapy can have minor and major complications, most of which occur as a result of gas or sclerosant leakage into the systemic venous system. Conventionally, the saphenofemoral junction is occluded by digital pressure to prevent escape of sclerosant foam into the deep venous system. We propose balloon control of the saphenofemoral junction to prevent sclerosant leakage. This also promotes foam contact with the endothelium in a prolonged, controlled fashion. This method requires no anesthesia, is suitable for ambulatory care, and has been safe and successful in all five cases. Duplex examinations at 1 week and 3 months have shown complete obliteration of the great saphenous vein using this technique.