Noninvasive Venous Waveform Analysis Correlates With Pulmonary Capillary Wedge Pressure and Predicts 30-Day Admission in Patients With Heart Failure Undergoing Right Heart Catheterization.

BACKGROUND: Heart failure is the leading cause of hospitalization in the elderly and readmission is common. Clinical indicators of congestion may not precede acute congestion with enough time to prevent hospital admission for heart failure. Thus, there is a large and unmet need for accurate, noninvasive assessment of congestion. Noninvasive venous waveform analysis in heart failure (NIVAHF) is a novel, noninvasive technology that monitors intravascular volume status and hemodynamic congestion. The objective of this study was to determine the correlation of NIVAHF with pulmonary capillary wedge pressure (PCWP) and the ability of NIVAHF to predict 30-day admission after right heart catheterization. METHODS AND RESULTS: The prototype NIVAHF device was compared with the PCWP in 106 patients undergoing right heart catheterization. The NIVAHF algorithm was developed and trained to estimate the PCWP. NIVA scores and central hemodynamic parameters (PCWP, pulmonary artery diastolic pressure, and cardiac output) were evaluated in 84 patients undergoing outpatient right heart catheterization. Receiver operating characteristic curves were used to determine whether a NIVA score predicted 30-day hospital admission. The NIVA score demonstrated a positive correlation with PCWP (r = 0.92, n = 106, P < .0001). The NIVA score at the time of hospital discharge predicted 30-day admission with an AUC of 0.84, a NIVA score of more than 18 predicted admission with a sensitivity of 91% and specificity of 56%. Residual analysis suggested that no single patient demographic confounded the predictive accuracy of the NIVA score. CONCLUSIONS: The NIVAHF score is a noninvasive monitoring technology that is designed to provide an estimate of PCWP. A NIVA score of more than 18 indicated an increased risk for 30-day hospital admission. This noninvasive measurement has the potential for guiding decongestive therapy and the prevention of hospital admission in patients with heart failure.

Antifibrinolytics Are Not Associated With Reduced Blood Loss in Minimally-Invasive Endoscopic-Assisted Craniectomy for Repair of Single-Suture Craniosynostosis.

ABSTRACT: Minimally-invasive endoscopic-assisted craniectomy (EAC) achieves similar functional and cosmetic outcomes, whereas reducing morbidity risk that is often associated with complex cranial vault reconstruction. Antifibrinolytics (AF) usage to limit blood loss and transfusion requirements during complex cranial vault reconstruction has been studied extensively; however, studies are limited for AF therapy in EAC. The aim of this single-center retrospective observational cohort pilot study was to evaluate whether the use of AF was associated with reduced blood loss in infants undergoing EAC. The authors hypothesized that there would be no difference in blood loss between patients who received AF and those that did not receive AF during EAC. Non-syndromic patients who underwent single-suture EAC were retrospectively evaluated. Primary outcome measure was intraoperative calculated blood loss (mL/kg). Secondary outcome measures included perioperative red blood cells transfusion volumes, number of blood donor exposures, and pediatric intensive care unit and total hospital length of stay. Study cohort demographic and outcome data were analyzed; Fisher exact test was used for categorical data, Student t test was used for continuous data. A P value of <0.05 was considered statistically significant. Forty-nine EAC patients were included in the study with 34 patients in the AF cohort and 15 patients in the non-AF cohort. There were no significant differences in demographics between the 2 groups. Additionally, there was no significant difference in intraoperative calculated blood loss or any secondary outcome measure. In our single-suture EAC study cohorts, AF administration was not associated with a decrease in blood loss when compared to those that did not receive AF therapy.

Hemodynamic Parameters in the Assessment of Fluid Status in a Porcine Hemorrhage and Resuscitation Model.

BACKGROUND: Measuring fluid status during intraoperative hemorrhage is challenging, but detection and quantification of fluid overload is far more difficult. Using a porcine model of hemorrhage and over-resuscitation, it is hypothesized that centrally obtained hemodynamic parameters will predict volume status more accurately than peripherally obtained vital signs. METHODS: Eight anesthetized female pigs were hemorrhaged at 30 ml/min to a blood loss of 400 ml. After each 100 ml of hemorrhage, vital signs (heart rate, systolic blood pressure, mean arterial pressure, diastolic blood pressure, pulse pressure, pulse pressure variation) and centrally obtained hemodynamic parameters (mean pulmonary artery pressure, pulmonary capillary wedge pressure, central venous pressure, cardiac output) were obtained. Blood volume was restored, and the pigs were over-resuscitated with 2,500 ml of crystalloid, collecting parameters after each 500-ml bolus. Hemorrhage and resuscitation phases were analyzed separately to determine differences among parameters over the range of volume. Conformity of parameters during hemorrhage or over-resuscitation was assessed. RESULTS: During the course of hemorrhage, changes from baseline euvolemia were observed in vital signs (systolic blood pressure, diastolic blood pressure, and mean arterial pressure) after 100 ml of blood loss. Central hemodynamic parameters (mean pulmonary artery pressure and pulmonary capillary wedge pressure) were changed after 200 ml of blood loss, and central venous pressure after 300 ml of blood loss. During the course of resuscitative volume overload, changes were observed from baseline euvolemia in mean pulmonary artery pressure and central venous pressure after 500-ml resuscitation, in pulmonary capillary wedge pressure after 1,000-ml resuscitation, and cardiac output after 2,500-ml resuscitation. In contrast to hemorrhage, vital sign parameters did not change during over-resuscitation. The strongest linear correlation was observed with pulmonary capillary wedge pressure in both hemorrhage (r2 = 0.99) and volume overload (r2 = 0.98). CONCLUSIONS: Pulmonary capillary wedge pressure is the most accurate parameter to track both hemorrhage and over-resuscitation, demonstrating the unmet clinical need for a less invasive pulmonary capillary wedge pressure equivalent.

Observational Study of Noninvasive Venous Waveform Analysis to Assess Intracardiac Filling Pressures During Right Heart Catheterization.

BACKGROUND: Outpatient monitoring and management of patients with heart failure (HF) reduces hospitalizations and health care costs. However, the availability of noninvasive approaches to assess congestion is limited. Noninvasive venous waveform analysis (NIVA) uses a unique physiologic signal, the morphology of the venous waveform, to assess intracardiac filling pressures. This study is a proof of concept analysis of the correlation between NIVA value and pulmonary capillary wedge pressure (PCWP) and the ability of the NIVA value to predict PCWP > 18 mmHg in subjects undergoing elective right heart catheterization (RHC). PCWP was also compared across common clinical correlates of congestion. METHODS AND RESULTS: A prototype NIVA device, which consists of a piezoelectric sensor placed over the skin on the volar aspect of the wrist, connected to a data-capture control box, was used to collect venous waveforms in 96 patients during RHC. PCWP was collected at end-expiration by an experienced cardiologist. The venous waveform signal was transformed to the frequency domain (Fourier transform), where a ratiometric algorithm of the frequencies of the pulse rate and its harmonics was used to derive a NIVA value. NIVA values were successfully captured in 83 of 96 enrolled patients. PCWP ranged from 4-40 mmHg with a median of 13 mmHg. NIVA values demonstrated a linear correlation with PCWP (r = 0.69, P < 0.05). CONCLUSIONS: This observational proof-of-concept study using a prototype NIVA device demonstrates a moderate correlation between NIVA value and PCWP in patients undergoing RHC. NIVA, thus, represents a promising developing technology for noninvasive assessment of congestion in spontaneously breathing patients.

Follow-up imaging of traumatic vertebral artery dissections is unnecessary in asymptomatic patients.

OBJECTIVE: Routine computed tomography (CT) imaging in trauma patients has led to increased recognition of blunt vertebral artery injuries (BVIs). We sought to determine the prevalence of strokes, injury progression, and need for intervention in patients with BVI. METHODS: Consecutive patients presenting with BVI during 2 years were identified from the institutional trauma registry. Inpatient records, imaging studies, and follow-up data were reviewed in detail from the electronic medical record. RESULTS: There were 76 BVIs identified in 70 patients (64% male; mean age, 47 ± 19 years); bilateral injuries occurred in 6 patients. Five patients who arrived at the hospital intubated had evidence of posterior circulation infarcts on admission CT, whereas one additional patient had evidence of a posterior circulation infarct attributed to complications of late spinal surgery. Four of the five patients with infarcts on admission CT survived to discharge, but only one had residual stroke symptoms. Minor (grade 1 or grade 2) injuries occurred in 25 (36%) patients; severe (grade 3 or grade 4) injuries occurred in 45 (64%). Twelve patients died of associated injuries (eight with severe BVI, four with minor BVI). Stepwise logistic regression analysis selected age (odds ratio, 1.14; confidence interval, 1.04-1.25; P < .001) and intubation on arrival (odds ratio, 450.4; confidence interval, 17.41-1645.51; P < .001) as independent predictors of hospital stroke and death. Of the 58 surviving to discharge, 31 (53%) returned for follow-up CT scans. Six of 10 (60%) patients with minor injuries had resolution or improvement compared with 3 of 21 (14%) with severe injuries (P = .027). One patient (10%) with a minor BVI and two patients (10%) with severe BVI had radiologic progression, but none were clinically significant. During a mean follow-up of 15 ± 13 months, none of the study patients had treatment (surgical or interventional) for BVI, and there were no delayed strokes. Only five patients in this series had vertebral pseudoaneurysms, which limits conclusions about this type of BVI. CONCLUSIONS: These data suggest that BVI-related strokes are present at the time of admission and do not have clinical sequelae. No late strokes occurred in this series, and no surgical or interventional treatments were required even in the presence of radiographic worsening. The relatively few cases of vertebral pseudoaneurysms in this series limit any conclusions about these specific lesions. However, these data indicate that follow-up imaging of nonaneurysmal BVI is not necessary in adults who are found to be asymptomatic on follow-up.

Hyperlactemia Predicts Surgical Mortality in Patients Presenting With Acute Stanford Type-A Aortic Dissection.

OBJECTIVE: Inspired by the limited facility of the Penn classification, the authors aimed to determine a rapid and optimal preoperative assessment tool to predict surgical mortality after acute Stanford type-A aortic dissection (AAAD) repair. DESIGN: Patients who underwent an attempted surgical repair of AAAD were determined using a de-identified single institution database. The charts of 144 patients were reviewed retrospectively for preoperative demographics and surrogates for disease severity and malperfusion. Bivariate analysis was used to determine significant (p≤0.05) predictors of in-hospital and 1-year mortality, the primary endpoints. Receiver operating characteristic curve generation was used to define optimal cut-off values for continuous predictors. SETTING: Single center, level 1 trauma, university teaching hospital. PARTICIPANTS: The study included 144 cardiac surgical patients with acute type-A aortic dissection presenting for surgical correction. INTERVENTIONS: Surgical repair of aortic dissection with preoperative laboratory samples drawn before patient transfer to the operating room or immediately after arterial catheter placement intraoperatively. MEASUREMENTS AND MAIN RESULTS: The study cohort comprised 144 patients. In-hospital mortality was 9%, and the 1-year mortality rate was 17%. Variables that demonstrated a correlation with in-hospital mortality included an elevated serum lactic acid level (odds ratio [OR] 1.5 [1.3-1.9], p<0.001), a depressed ejection fraction (OR 0.91 [0.86-0.96], p = .001), effusion (OR 4.8 [1.02-22.5], p = 0.04), neurologic change (OR 5.3 [1.6-17.4], p = 0.006), severe aortic regurgitation (OR 8.2 [2.0-33.9], p = 0.006), and cardiopulmonary resuscitation (OR 6.8 [1.7-26.9], p = 0.01). Only an increased serum lactic acid level demonstrated a trend with 1-year mortality using univariate Cox regression (hazard ratio 1.1 [1.0-1.1], p = 0.006). Receiver operating characteristic analysis revealed optimal cut-off lactic acid levels of 6.0 mmol/L and 6.9 mmol/L for in-hospital and 1-year mortality, respectively. CONCLUSION: Lactic acidosis, ostensibly as a surrogate for systemic malperfusion, represents a novel, accurate, and easily obtainable preoperative predictor of short-term mortality after attempted AAAD repair. These data may improve identification of patients who would not benefit from surgery.

Prediction of Prolonged Ventilation after Coronary Artery Bypass Grafting: Data from an Artificial Neural Network.

OBJECTIVES: The need for mechanical ventilation 24 hours after coronary artery bypass grafting (CABG) is considered a morbidity by the Society of Thoracic Surgeons. The purpose of this investigation was twofold: to identify simple preoperative patient factors independently associated with prolonged ventilation and to optimize prediction and early identification of patients prone to prolonged ventilation using an artificial neural network (ANN). METHODS: Using the institutional Adult Cardiac Database, 738 patients who underwent CABG since 2005 were reviewed for preoperative factors independently associated with prolonged postoperative ventilation. Prediction of prolonged ventilation from the identified variables was modeled using both "traditional" multiple logistic regression and an ANN. The two models were compared using Pearson r2 and area under the curve (AUC) parameters. RESULTS: Of 738 included patients, 14% (104/738) required mechanical ventilation ≥ 24 hours postoperatively. Upon multivariate analysis, higher body-mass index (BMI; odds ratio [OR] 1.10 per unit, P < 0.001), lower ejection fraction (OR 0.97 per %, P = 0.01) and use of cardiopulmonary bypass (OR 2.59, P = 0.02) were independently predictive of prolonged ventilation. The Pearson r2 and AUC of the multivariate nominal logistic regression model were 0.086 and 0.698 ± 0.05, respectively; analogous statistics of the ANN model were 0.159 and 0.732 ± 0.05, respectively.BMI, ejection fraction and cardiopulmonary bypass represent three simple factors that may predict prolonged ventilation after CABG. Early identification of these patients can be optimized using an ANN, an emerging paradigm for clinical outcomes modeling that may consider complex relationships among these variables.

Unregulated saphenous vein graft distension decreases tissue viscoelasticity.

OBJECTIVES: Unregulated intraoperative distension of human saphenous vein (SV) graft leads to supraphysiologic luminal pressures and causes acute physiologic and cellular injury to the conduit. The effect of distension on tissue viscoelasticity, a biophysical property critical to a successful graft, is not well described. In this investigation, we quantify the loss of viscoelasticity in SV deformed by distension and compare the results to tissue distended in a pressure-controlled fashion. MATERIALS AND METHODS: Unmanipulated porcine SV was used as a control or distended without regulation and distended with an in-line pressure release valve (PRV). Rings were cut from these tissues and suspended on a muscle bath. Force versus time tracings of tissue constricted with KCl (110 mM) and relaxed with sodium nitroprusside (SNP) were fit to the Hill model of viscoelasticity, using mean absolute error (MAE) and r2-goodness of fit as measures of conformity. RESULTS: One-way ANOVA analysis demonstrated that, in tissue distended manually, the MAE was significantly greater and the r2-goodness of fit was significantly lower than both undistended tissues and tissues distended with a PRV (p<0.05) in KCl-induced vasoconstriction and SNP-induced vasodilation. CONCLUSIONS: Unregulated manual distension of SV graft causes loss of viscoelasticity and such loss may be mitigated with the use of an in-line PRV.

Brilliant blue FCF is a nontoxic dye for saphenous vein graft marking that abrogates response to injury.

BACKGROUND: Injury to saphenous vein grafts during surgical preparation may contribute to the subsequent development of intimal hyperplasia, the primary cause of graft failure. Surgical skin markers currently used for vascular marking contain gentian violet and isopropanol, which damage tissue and impair physiologic functions. Brilliant blue FCF (FCF) is a nontoxic dye alternative that may also ameliorate preparation-induced injury. METHODS: Porcine saphenous vein (PSV) was used to evaluate the effect of FCF on physiologic responses in a muscle bath. Cytotoxicity of FCF was measured using human umbilical venous smooth muscle cells. Effect of FCF on the development of intimal hyperplasia was evaluated in organ culture using PSV. Intracellular calcium fluxes and contractile responses were measured in response to agonists and inhibitors in rat aorta and human saphenous vein. RESULTS: Marking with FCF did not impair smooth muscle contractile responses and restored stretch injury-induced loss in smooth muscle contractility of PSV. Gentian violet has cytotoxic effects on human umbilical venous smooth muscle cells, whereas FCF is nontoxic. FCF inhibited intimal thickening in PSV in organ culture. Contraction induced by 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate and intracellular calcium flux were inhibited by FCF, oxidized adenosine triphosphate, KN-62, and brilliant blue G, suggesting that FCF may inhibit the purinergic receptor P2X7. CONCLUSIONS: Our studies indicated that FCF is a nontoxic marking dye for vein grafts that ameliorates vein graft injury and prevents intimal thickening, possibly due to P2X7 receptor inhibition. FCF represents a nontoxic alternative for vein graft marking and a potentially therapeutic approach to enhance outcome in autologous transplantation of human saphenous vein into the coronary and peripheral arterial circulation.

Aortic arch involvement worsens the prognosis of type B aortic dissections.

OBJECTIVE: Medical management of acute aortic dissections limited to the descending thoracic aorta (AD-desc) is associated with acceptable outcomes. Uncertainty remains about whether acute type B aortic dissections involving the aortic arch (AD-arch) have an increased risk of retrograde extension into the ascending aorta or other dissection-related complications. This study compared outcomes of AD-arch with AD-desc managed medically. METHODS: Consecutive patients admitted from 2005 to 2014 with acute aortic dissections not involving the ascending aorta were retrospectively analyzed. Primary end points included dissection-related death and operative intervention. RESULTS: The study included 99 patients (63% men; mean age, 60 ± 14 years) with acute aortic dissections. Dissections were limited to the aorta distal to the left subclavian artery (AD-desc) in 79 patients (80%), and 20 (20%) had involvement of the left subclavian (n = 16), left common carotid (n = 1), or innominate (n = 3) arteries (AD-arch). Dissections ended proximal to the celiac artery in 30 patients (30%), between the celiac artery and aortic bifurcation in 36 (36%), and distal to the aortic bifurcation in 33 (33%). During medical management, further proximal extension into the arch occurred in two AD-arch patients and one AD-desc patient (P < .05), but proximal dissection into the ascending aorta occurred in only one AD-arch patient with Marfan disease. Compared with patients with AD-desc, those with AD-arch were younger (53 ± 12.5 vs 62 ± 16 years; P < .01) and had more frequent early interventions (40% vs 19%; P = .047), cardiac complications (35% vs 11%; P < .01), and neurologic events (25% vs 6%; P < .01). Seven AD-arch patients (35%) and nine AD-desc patients (11%) died of dissection-related causes (P < .01). Among survivors, late interventions were performed in four of eight AD-arch patients (50%) and in six of 58 AD-desc patients (10%; P = .02). Medical treatment without intervention was successful in four AD-arch patients (20%) and in 52 AD-desc patients (66%; P < .001). Multivariate logistic regression retained arch involvement as the sole predictor of dissection-related death (odds ratio, 4.2; 95% confidence interval, 1.3-13.4) and failure of medical treatment (odds ratio, 7.7; 95% confidence interval, 2.5-29). The distal extent of dissection had no bearing on outcome. CONCLUSIONS: AD-arch dissections are associated with a higher risk of cardiac and neurologic events, need for early intervention, and dissection-related death than AD-desc dissections. Because further proximal dissections into the ascending aorta were rare in this study, medical management appears to be safe as the initial treatment of AD-arch dissections. However, surgeons should be aware of the increased risk of complications and the potential need for urgent interventions in these patients.

Traditional graft preparation decreases physiologic responses, diminishes viscoelasticity, and reduces cellular viability of the conduit: A porcine saphenous vein model.

Traditional methods of intraoperative human saphenous vein preparation for use as bypass grafts can be deleterious to the conduit. The purpose of this study was to characterize acute graft preparation injury, and to mitigate this harm via an improved preparation technique. Porcine saphenous veins were surgically harvested (unprepared controls, UnP) and prepared using traditional (TraP) and improved preparations (ImP). The TraP used unregulated radial distension, marking with a surgical skin marker and preservation in heparinized normal saline. ImP used pressure-regulated distension, brilliant blue FCF-based pen marking and preservation in heparinized Plasma-Lyte A. Rings from each preparation were suspended in a muscle bath for characterization of physiologic responses to vasoactive agents and viscoelasticity. Cellular viability was assessed using the methyl thiazolyl tetrazolium (MTT) assay and the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay for apoptosis. Contractile responses to potassium chloride (110 mM) and phenylephrine (10 µM), and endothelial-dependent and independent vasodilatory responses to carbachol (0.5 µM) and sodium nitroprusside (1 µM), respectively, were decreased in TraP tissues compared to both UnP and ImP tissues (p ⩽ 0.05). TraP tissues demonstrated diminished viscoelasticity relative to UnP and ImP tissues (p ⩽ 0.05), and reduced cellular viability relative to UnP control (p ⩽ 0.01) by the MTT assay. On the TUNEL assay, TraP tissues demonstrated a greater degree of apoptosis relative to UnP and ImP tissues (p ⩽ 0.01). In conclusion, an improved preparation technique prevents vascular graft smooth muscle and endothelial injury observed in tissues prepared using a traditional approach.

Prediction of excess weight loss after laparoscopic Roux-en-Y gastric bypass: data from an artificial neural network.

INTRODUCTION: Laparoscopic Roux-en-Y gastric bypass (LRYGB) has become the gold standard for surgical weight loss. The success of LRYGB may be measured by excess body mass index loss (%EBMIL) over 25 kg/m(2), which is partially determined by multiple patient factors. In this study, artificial neural network (ANN) modeling was used to derive a reasonable estimate of expected postoperative weight loss using only known preoperative patient variables. Additionally, ANN modeling allowed for the discriminant prediction of achievement of benchmark 50% EBMIL at 1 year postoperatively. METHODS: Six hundred and forty-seven LRYGB included patients were retrospectively reviewed for preoperative factors independently associated with EBMIL at 180 and 365 days postoperatively (EBMIL180 and EBMIL365, respectively). Previously validated factors were selectively analyzed, including age; race; gender; preoperative BMI (BMI0); hemoglobin; and diagnoses of hypertension (HTN), diabetes mellitus (DM), and depression or anxiety disorder. Variables significant upon multivariate analysis (P < .05) were modeled by "traditional" multiple linear regression and an ANN, to predict %EBMIL180 and %EBMIL365. RESULTS: The mean EBMIL180 and EBMIL365 were 56.4 ± 16.5 % and 73.5 ± 21.5%, corresponding to total body weight losses of 25.7 ± 5.9% and 33.6 ± 8.0%, respectively. Upon multivariate analysis, independent factors associated with EBMIL180 included black race (B = -6.3%, P < .001), BMI0 (B = -1.1%/unit BMI, P < .001), and DM (B = -3.2%, P < .004). For EBMIL365, independently associated factors were female gender (B = 6.4%, P < .001), black race (B = -6.7%, P < .001), BMI0 (B = -1.2%/unit BMI, P < .001), HTN (B = -3.7%, P = .03), and DM (B = -6.0%, P < .001). Pearson r(2) values for the multiple linear regression and ANN models were 0.38 (EBMIL180) and 0.35 (EBMIL365), and 0.42 (EBMIL180) and 0.38 (EBMIL365), respectively. ANN prediction of benchmark 50% EBMIL at 365 days generated an area under the curve of 0.78 ± 0.03 in the training set (n = 518) and 0.83 ± 0.04 (n = 129) in the validation set. CONCLUSIONS: Available at https://redcap.vanderbilt.edu/surveys/?s=3HCR43AKXR, this or other ANN models may be used to provide an optimized estimate of postoperative EBMIL following LRYGB.

Impaired weight loss in laparoscopic adjustable gastric banding patients over 50 years of age: diabetes mellitus as an independent risk factor.

INTRODUCTION: Laparoscopic adjustable gastric banding (LAGB) represents a safe and effective bariatric procedure, particularly for patients over 50. Preoperative risk factors for impaired post-LAGB excess weight loss are not well characterized for this population. This study aimed to identify demographics, characteristics or comorbidities associated with excess weight loss at 6 and 12 months postoperatively (EWL180 and EWL365, respectively) for these patients. METHODS: One hundred and seventeen LAGB patients >50 years of age from 2005 to 2014 were retrospectively reviewed for factors potentially associated with EWL180 and EWL365. Rationally selected variables chosen for analysis included age, race, gender, initial body mass index and preoperative weight loss; comorbidities assessed included hypertension, psychiatric disorders and diabetes mellitus (DM). Variables correlated with EWL180 or EWL365 on bivariate linear regression analysis (P ≤ .05) were input into multivariate linear regression analysis to confirm independent association. RESULTS: Preoperative DM (B = -9.1% EWL; 95% CI -13.6, -4.5%; P < .001) and African-American race (B = -8.8% EWL; 95% CI -17.3, -0.3%; P = .05) were independent risk factors for impaired EWL180. Only DM was a risk factor for impaired EWL365 (B = -9.7% EWL; 95% CI -17.7, -1.8%; P = .02). CONCLUSIONS: LAGB is a successful operation in patients >50 years of age. Preoperative DM is an independent risk factor for impaired EWL in this cohort.

Red cell distribution width is a novel biomarker that predicts excess body-mass index loss 1 year after laparoscopic Roux-en-Y gastric bypass.

INTRODUCTION: Bariatric surgery is the most effective method for producing sustained weight loss, improving obesity-associated comorbidities and reducing inflammation in the morbidly obese population. The red cell distribution width (RDW) is a novel marker of inflammation that is usually reported as part of a complete blood count. In this study, we tested our hypothesis that red cell distribution width might represent a novel biomarker predictive of excess body-mass index loss (EBMIL) following laparoscopic Roux-en-Y gastric bypass (LRYGB). METHODS: Five hundred and forty-seven LRYGB patients included from a single institution were individually reviewed, noting both preoperative RDW and percent excess BMI loss at 6 months and 1 year post-LRYGB (%EBMIL180 and %EBMIL365, respectively). Bivariate and multivariate linear regression analysis was conducted between age, gender, initial body-mass index (BMI0) and RDW and each of the two endpoints, to assess the independence of RDW as a predictor of postoperative success. RESULTS: The median RDW was 13.9 (13.3-14.6) %, and median EBMIL180 and EBMIL365 were 55.4 (45.2-66.7) % and 71.3 (58.9-87.8) %, respectively. After controlling for age, gender and BMI0, RDW was associated with %EBMIL365 (B = -1.4 [-2.8 to -0.002] %, P = .05), but not %EBMIL180 (B = -0.6 [-1.6 to 0.5] %, P = .30. Upon Kruskal-Wallis analysis, patients with a preoperative RDW > 15.0 % had significantly lower %EBMIL than those in the <13.0 % (P < .001) and 13.0-15.0 % (P < .01) strata. CONCLUSIONS: RDW is predictive of EBMIL at 1 year following LRYGB. This represents a novel preoperative biomarker that may provide clinically useful prognostic information.

An Evaluation of Induced Failure Modes in the Belmont® Rapid Infuser.

BACKGROUND: Rapid infusers are vital tools during massive hemorrhage and resuscitation. Sporadic reports of overheating and shutdown of the Belmont® Rapid Infuser, a commonly used system, have been attributed to 1-sided clot blockage of the fluid path. We investigated multiple causes of failure of this device. METHODS: Packed red blood cells and thawed fresh frozen plasma with normal saline solution were used as base fluids for serial 10-minute trials using standard disposable sets in 2 Belmont devices. Possible contributors to device failure, including calcium-containing solutions and external leakage currents, were evaluated. Thermographic images of the heater and disposable cartridges were recorded. The effects of complete unilateral clotting were modeled by sealing half of the disposable cartridge with epoxy. RESULTS: Clotting on the surface of the heat exchanger coil increased with calcium concentration and was only observed at calcium concentrations >12.0 mmol/L (P < 0.0001) in a 1:1 plasma:red blood cell mixture, resulting in high-pressure downstream occlusion alarms and interruption of flow. CONCLUSIONS: Clot-based occlusion can be induced in the Belmont Rapid Infuser under unrealistic conditions. In the absence of complete unilateral flow blockage, we did not observe any significant overheating of the infuser under extreme operating conditions.

Preoperative Predictors of 30-Day Mortality and Prolonged Length of Stay after Above-Knee Amputation.

BACKGROUND: The above-knee amputation (AKA) is an operation of last resort with high postoperative morbidity and mortality. This study identifies preoperative risk factors predictive of both 30-day mortality and extended length of stay (LOS) in AKA patients. METHODS: Two hundred ninety-five AKA patients from 2004 to 2013 from a single institution were retrospectively reviewed using a deidentified electronic medical record. Rationally selected factors potentially influencing 30-day mortality and LOS were chosen, including demographics, etiologies, vascular surgical history, lifestyle factors, comorbidities, and laboratory values. Variables trending with one of the end points on bivariate analysis (P ≤ 0.10) were entered into multivariate forward stepwise regression models to determine independence as a risk factor (P ≤ 0.05). Subgroup analysis of AKA patients without a traumatic, burn, or malignant etiology was similarly conducted. RESULTS: Within the 295 patient cohort, 60% of the patients were male, 18% were African American, mean age was 58 years and mean body mass index was 28 kg/m(2). The 30-day mortality rate was 9%, and mean postoperative LOS of discharged patients was 9.3 days. Upon logistic regression, thrombocytopenia (platelet count < 250 × 10(6)/mL, P < 0.001, odds ratio 6.1) and preoperative septic shock (P = 0.02, odds ratio 5.1) were identified as independent risk factors for 30-day mortality. Upon linear regression, burn etiology (P < 0.001, B = 15.8 days), leukocytosis (white blood cell count > 12 × 10(6)/mL, P < 0.001, B = 6.2 days), and guillotine amputation (P < 0.001, B = 7.6 days) were independently associated with prolonged LOS. Excluding patients with AKAs due to trauma, burn, or malignancy, only thrombocytopenia (platelet count < 250 × 10(6)/mL, P < 0.001, odds ratio 10.2) and leukocytosis (white blood cell count > 12 × 10(6)/mL, P = 0.01, B = 5.2 days) were independent risk factors for in-hospital mortality and prolonged LOS, respectively. CONCLUSIONS: Preoperative septic shock and thrombocytopenia are independent risk factors for 30-day mortality after AKA, while burn etiology, leukocytosis, and guillotine amputation contribute to prolonged LOS. Awareness of these risk factors may help enhance both preoperative decision making and expectations of the hospital admission.

Prediction of in-hospital mortality after ruptured abdominal aortic aneurysm repair using an artificial neural network.

OBJECTIVE: Ruptured abdominal aortic aneurysm (rAAA) carries a high mortality rate, even with prompt transfer to a medical center. An artificial neural network (ANN) is a computational model that improves predictive ability through pattern recognition while continually adapting to new input data. The goal of this study was to effectively use ANN modeling to provide vascular surgeons a discriminant adjunct to assess the likelihood of in-hospital mortality on a pending rAAA admission using easily obtainable patient information from the field. METHODS: Of 332 total patients from a single institution from 1998 to 2013 who had attempted rAAA repair, 125 were reviewed for preoperative factors associated with in-hospital mortality; 108 patients received an open operation, and 17 patients received endovascular repair. Five variables were found significant on multivariate analysis (P < .05), and four of these five (preoperative shock, loss of consciousness, cardiac arrest, and age) were modeled by multiple logistic regression and an ANN. These predictive models were compared against the Glasgow Aneurysm Score. All models were assessed by generation of receiver operating characteristic curves and actual vs predicted outcomes plots, with area under the curve and Pearson r(2) value as the primary measures of discriminant ability. RESULTS: Of the 125 patients, 53 (42%) did not survive to discharge. Five preoperative factors were significant (P < .05) independent predictors of in-hospital mortality in multivariate analysis: advanced age, renal disease, loss of consciousness, cardiac arrest, and shock, although renal disease was excluded from the models. The sequential accumulation of zero to four of these risk factors progressively increased overall mortality rate, from 11% to 16% to 44% to 76% to 89% (age ≥ 70 years considered a risk factor). Algorithms derived from multiple logistic regression, ANN, and Glasgow Aneurysm Score models generated area under the curve values of 0.85 ± 0.04, 0.88 ± 0.04 (training set), and 0.77 ± 0.06 and Pearson r(2) values of .36, .52 and .17, respectively. The ANN model represented the most discriminant of the three. CONCLUSIONS: An ANN-based predictive model may represent a simple, useful, and highly discriminant adjunct to the vascular surgeon in accurately identifying those patients who may carry a high mortality risk from attempted repair of rAAA, using only easily definable preoperative variables. Although still requiring external validation, our model is available for demonstration at https://redcap.vanderbilt.edu/surveys/?s=NN97NM7DTK.

Race as a predictor of delay from diagnosis to endarterectomy in clinically significant carotid stenosis.

OBJECTIVE: Prompt carotid endarterectomy (CEA) in clinically significant carotid stenosis is important in the prevention of neurologic sequelae. The greatest benefit from surgery is obtained by prompt revascularization on diagnosis. It has been demonstrated that black patients both receive CEA less frequently than white patients do and experience worse postoperative outcomes. We sought to test our hypothesis that black race is an independent risk factor for a prolonged time from sonographic diagnosis of carotid stenosis warranting surgery to the day of operation (TDO). METHODS: From 1998 to 2013 at a single institution, 166 CEA patients were retrospectively reviewed using Synthetic Derivative, a de-identified electronic medical record. Factors potentially affecting TDO, including demographics, preoperative cardiac stress testing, degree of stenosis, smoking status, and comorbidities, were noted. Multivariate analysis was performed on variables that trended with prolonged TDO on univariate analysis (P < .10) to determine independent (P < .05) predictors of TDO. Subgroup analyses were further performed on the symptomatic and asymptomatic stenosis cohorts. RESULTS: There were 32 black patients and 134 white patients studied; the mean TDO was 78 ± 17 days vs 33 ± 3 days, respectively (P < .001). In addition to the need for preoperative cardiac stress testing, black race was the only variable that demonstrated a trend with (P < .10) or was an independent risk factor for (P < .05) prolonged TDO among all patients (B = 42 days; P < .001) and within the symptomatic (B = 35 days; P = .08) and asymptomatic (B = 35 days; P = .003) cohorts. On Kaplan-Meier analysis, black patients in each stratum of symptomatology (all, symptomatic, and asymptomatic patients) experienced prolonged TDO (log-rank, P < .03 for all three groups). CONCLUSIONS: Black race is a risk factor for a temporal delay in CEA for carotid stenosis. Awareness of this disparity may help surgeons avoid undesirable delays in operation for their black patients.

Surgical vein graft preparation promotes cellular dysfunction, oxidative stress, and intimal hyperplasia in human saphenous vein.

INTRODUCTION: Human saphenous vein (HSV) is the most widely used bypass conduit for peripheral and coronary vascular reconstructions. However, outcomes are limited by a high rate of intimal hyperplasia (IH). HSV undergoes a series of ex vivo surgical manipulations prior to implantation, including hydrostatic distension, marking, and warm ischemia in solution. We investigated the impact of surgical preparation on HSV cellular function and development of IH in organ culture. We hypothesized that oxidative stress is a mediator of HSV dysfunction. METHODS: HSV was collected from patients undergoing vascular bypass before and after surgical preparation. Smooth muscle and endothelial function were measured using a muscle bath. Endothelial preservation was assessed with immunohistochemical staining. An organ culture model was used to investigate the influence of surgical preparation injury on the development of IH. Superoxide levels were measured using a high-performance liquid chromatography-based assay. The influence of oxidative stress on HSV physiologic responses was investigated by exposing HSV to hydrogen peroxide (H2O2). RESULTS: Surgical vein graft preparation resulted in smooth muscle and endothelial dysfunction, endothelial denudation, diminished endothelial nitric oxide synthase staining, development of increased IH, and increased levels of reactive oxygen species. Experimental induction of oxidative stress in unmanipulated HSV by treatment with H2O2 promoted endothelial dysfunction. Duration of storage time in solution did not contribute to smooth muscle or endothelial dysfunction. CONCLUSIONS: Surgical vein graft preparation causes dysfunction of the smooth muscle and endothelium, endothelial denudation, reduced endothelial nitric oxide synthase expression, and promotes IH in organ culture. Moreover, increased levels of reactive oxygen species are produced and may promote further vein graft dysfunction. These results argue for less injurious means of preparing HSV prior to autologous transplantation into the arterial circulation.