Clamp Site Research Articles

Development of novel rectal/uterine clamping device

We developed a novel clamping device for laparoscopic surgery, free from conventional pinch structure, capable of uniformly occluding any ductal organ. This study aimed to evaluate performance of the new clamper compared to the pinch-type clamper. The new clamper consists of two metal bars with ties at each end, which enables parallel clamping. A resected porcine stomach was used, with an infusion tube at the anal end to increase intra-luminal pressure. The oral side of the stomach was clamped with either the new clamper or the pinch-type clamper, and their performances were evaluated in qualitative and semi-quantitative manner. Qualitative evaluation involved imaging the clamping site at intra-gastric pressures from 0 to 15 mmHg using microfocus computed tomography. The new clamper showed no gap even under increased intra-luminal pressure, while the pinch-type clamper showed a gap on the distal side. Quantitative evaluation measured bursting pressure under continuous air insufflation. Air leakages were observed in the new clamper at higher intra-luminal pressures than in the pinch-type clamper (46.1 mmHg vs. 13.6 mmHg, P < 0.01). Our new clamping device showed superior performance in preclinical setting compared to the conventional pinch-type clamper. We are currently working on its design freezing and aiming for early commercialization.

Identifying risk factors for postoperative ileus following open abdominal aortic aneurysm repair

BackgroundPostoperative ileus (POI) is a common complication following major abdominal surgery. The majority of the data available regarding POI after abdominal surgery is from the gastrointestinal and urological literature. These data have been extrapolated to vascular surgery, especially with regard to enhanced recovery programs for open abdominal aortic aneurysm (AAA) surgery. However, vascular patients are a unique patient population and extrapolation of gastrointestinal and urological data may not necessarily be appropriate. Therefore, the purpose of this study was to delineate the prevalence and risk factors of POI in patients undergoing open AAA surgery. MethodsThis was a retrospective, single-institution study of patients who underwent open AAA surgery from January 2016 to July 2023. Patients were excluded if they had undergone nonelective repairs or had expired within 72 hours of their index operation. The primary outcome was rates of POI, which was defined as the presence of two or more of the following after the third postoperative day: nausea and/or vomiting, inability to tolerate oral food intake, absence of flatus, abdominal distension, or radiological evidence of ileus. ResultsA total of 123 patients met study criteria with an overall POI rate of 8.9% (n = 11). Patients who developed a POI had a significantly lower body mass index (24.3 kg/m2 vs 27.1 kg/m2; P = .003), were more likely to undergo a transperitoneal approach (81.8% vs 42.0%; P = .022), midline laparotomy (81.8% vs 37.5%; P = .008), longer total clamp times (151.6 minutes vs 97.7 minutes; P = .018), greater amounts of intraoperative crystalloid infusion (3495 mL vs 2628 mL; P = .029), and were more likely to return to the operating room (27.3% vs 3.6%; P = .016). Proximal clamp site was not associated with POI (P=.463). Patients with POI also had higher rates of postoperative vasopressor use (100% vs 61.1%; P = .014) and greater amounts of oral morphine equivalents in the first 3 postoperative days (488.0 ± 216.0 mg vs 203.8 ± 29.6 mg; P = .016). Patients who developed POI had longer lengths of stay (12.5 days vs 7.6 days; P < .001), a longer duration of nasogastric tube decompression (5.9 days vs 2.2 days; P < .001), and a longer period of time before diet tolerance (9.1 days vs 3.7 days; P < .001). Of those who developed a POI (n = 11), four (36.4%) required total parental nutrition during the admission. ConclusionsPOI is a morbid complication among patients undergoing elective open AAA surgery that prolongs hospital stay. Patients at risk for developing a POI are those with a lower body mass index, as well as those who had an operative repair via a transperitoneal approach, midline laparotomy, longer clamp times, larger amounts of intraoperative crystalloid infusion, a return to the operating room, postoperative vasopressor use, and higher amounts of oral morphine equivalents. These data highlight important perioperative opportunities to decrease the prevalence of POI.

Impact of chronic kidney disease and end-stage renal disease on outcomes after complex endovascular and open aortic aneurysm repair

ObjectiveChronic kidney disease (CKD) and end-stage renal disease are traditionally associated with worse outcomes after endovascular aortic repair (EVAR) and open aneurysm repair (OAR) of abdominal aortic aneurysms (AAAs). However, there needs to be more data on complex AAA repair involving the aorta's visceral segment. This study stratifies complex AAA repair outcomes by CKD severity and dialysis dependence. MethodsAll patients undergoing elective OAR and fenestrated/branched EVAR (F-BEVAR) for complex AAA with preoperative renal function data captured by the Vascular Quality Initiative between January 2003 and September 2020 were analyzed. Patients were stratified by CKD class as follows: normal/mild (CKD 1 and 2), moderate (CKD class 3a), moderate to severe (CKD 3b), severe (CKD class 4 and 5), and dialysis. Only patients with clamp sites above one of the renal arteries were included for complex OAR. For F-BEVAR, patients with proximal landing zones below zone 5 (above celiac artery) were included, and distal landing zones between zones 1 and 5 were excluded. Primary outcomes were perioperative and 1-year mortality. Predictors of mortality were identified by Cox multivariate regression models. ResultsWe identified 7849 elective complex AAA repairs: 4230 (54%) complex OARs and 3619 (46%) F-BEVARs. Most patients were White (89%) and male (74%), with an average age of 72 ± 8 years. The patients who underwent F-BEVAR were older and had more comorbidities. Elective F-BEVAR for complex AAA started in 2012 and increased from 1.4% in 2012 to 58% in 2020 (P < .001). The OAR cohort had more perioperative complications, but less 1-year mortality. The normal/mild CKD cohort had the highest 1-year survival compared with other groups after both complex OAR and F-BEVAR. On Cox regression analysis, when compared with CKD 1-2, worsening CKD stage (CKD 3b: hazard ratio [HR], 2.5; 95% confidence interval [CI], 1.82-3.40; P < .001; CKD 4-5: HR, 1.9; 95% CI, 1.16-3.26; P = .011; and dialysis: HR, 4.4; 95% CI, 2.53-7.72; P < .001) were independently associated with 1-year survival after F-BEVAR. After complex OAR, worsening CKD stage but not dialysis was associated with 1-year mortality compared with CKD 1-2 (CKD 3b: HR, 1.6; 95% CI, 1.13-2.35; P = .009; CKD 4-5: HR, 3.4; 95% CI, 2.03-5.79; P < .001). ConclusionsCKD severity is an essential predictor of perioperative and 1-year mortality after complex AAA repair, irrespective of the treatment modality, which may reflect the natural history of CKD. Consideration should be given to raising the threshold for elective AAA repair in patients with moderate to severe CKD and end-stage renal disease, given the high 1-year mortality rate.

Using machine learning to predict outcomes following open abdominal aortic aneurysm repair

ObjectivePrediction of outcomes following open abdominal aortic aneurysm (AAA) repair remains challenging with a lack of widely used tools to guide perioperative management. We developed machine learning (ML) algorithms that predict outcomes following open AAA repair. MethodsThe Vascular Quality Initiative (VQI) database was used to identify patients who underwent elective open AAA repair between 2003 and 2023. Input features included 52 preoperative demographic/clinical variables. All available preoperative variables from VQI were used to maximize predictive performance. The primary outcome was in-hospital major adverse cardiovascular event (MACE; composite of myocardial infarction, stroke, or death). Secondary outcomes were individual components of the primary outcome, other in-hospital complications, and 1-year mortality and any reintervention. We split our data into training (70%) and test (30%) sets. Using 10-fold cross-validation, six ML models were trained using preoperative features (Extreme Gradient Boosting [XGBoost], random forest, Naïve Bayes classifier, support vector machine, artificial neural network, and logistic regression). The primary model evaluation metric was area under the receiver operating characteristic curve (AUROC). Model robustness was evaluated with calibration plot and Brier score. The top 10 predictive features in our final model were determined based on variable importance scores. Performance was assessed on subgroups based on age, sex, race, ethnicity, rurality, median area deprivation index, proximal clamp site, prior aortic surgery, and concomitant procedures. ResultsOverall, 12,027 patients were included. The primary outcome of in-hospital MACE occurred in 630 patients (5.2%). Compared with patients without a primary outcome, those who developed in-hospital MACE were older with more comorbidities, demonstrated poorer functional status, had more complex aneurysms, and were more likely to require concomitant procedures. Our best performing prediction model for in-hospital MACE was XGBoost, achieving an AUROC of 0.93 (95% confidence interval, 0.92-0.94). Comparatively, logistic regression had an AUROC of 0.71 (95% confidence interval, 0.70-0.73). For secondary outcomes, XGBoost achieved AUROCs between 0.84 and 0.94. The calibration plot showed good agreement between predicted and observed event probabilities with a Brier score of 0.05. These findings highlight the excellent predictive performance of the XGBoost model. The top three predictive features in our algorithm for in-hospital MACE following open AAA repair were: (1) coronary artery disease; (2) American Society of Anesthesiologists classification; and (3) proximal clamp site. Model performance remained robust on all subgroup analyses. ConclusionsOpen AAA repair outcomes can be accurately predicted using preoperative data with our ML models, which perform better than logistic regression. Our automated algorithms can help guide risk-mitigation strategies for patients being considered for open AAA repair to improve outcomes.

Greater Patient Travel Distance is Associated with Perioperative and One-Year Cost Increases After Complex Aortic Surgery

With increasing regionalization of complex aortic surgery within fewer US centers, patients may face increased travel burden when accessing aortic surgery. Longer travel distances have been associated with inferior outcomes after major surgery; however, the impacts of distance on reinterventions and costs have not been described. This study aims to assess the association between patient travel distance and longer-term outcomes including costs and reinterventions after complex aortic surgery. A retrospective review was conducted of all patients in the Vascular Implant Surveillance and Interventional Outcomes Network database undergoing complex endovascular aortic repair including internal iliac or visceral vessel involvement, complex thoracic endovascular aortic repair including Zone 0-2 proximal extent or branched devices, and complex open abdominal aortic aneurysm repair including suprarenal or higher clamp sites. Travel distance was stratified by Rural-Urban Commuting Area population-density category. Multinomial logistic regression models, negative-binomial models, and zero-inflated Poisson models were used to assess the association between travel distance and index procedural and comprehensive first-year costs, long-term imaging, and long-term reinterventions, respectively. Between 2011 and 2018, 8,782 patients underwent complex aortic surgery in the Vascular Implant Surveillance and Interventional Outcomes Network database, including 4,822 complex endovascular aortic repairs, 2,672 complex thoracic endovascular aortic repairs, and 1,288 complex open abdominal aortic aneurysm repairs. Median travel distance was 22.8 miles (interquartile range 8.6-54.8 miles, range 0-2,688.9 miles). Median age was 75years for all distance quintiles. Patients traveling farther were more likely to be female (26.8% in quintile 5 [Q5] vs. 19.9% in Q1, P<0.001) and to have had a prior aortic surgery (20.8% for Q5 vs. 5.9% for Q1, P<0.001). Patients traveling farther had higher index procedural costs, with adjusted odds ratio (OR) 2.34 (95% confidence interval [CI] 1.86-2.94, P<0.0001) of being in the highest cost tertile versus lowest for patients in Q5 vs. Q1. For patients with ≥ 1-year follow-up, those traveling farther had higher imaging costs, with adjusted Q5 OR 1.55 (95% CI 1.22-1.95, P=0.0002), and comprehensive first-year costs, with adjusted Q5 OR 2.06 (95% CI 1.57-2.70, P<0.0001). In contrast, patients traveling farther had similar numbers of reinterventions and imaging studies postoperatively. Patients traveling farther for complex aortic surgery have higher procedural costs, postoperative imaging costs, and comprehensive first-year costs. These patients should be targeted for increased care coordination for improved outcomes and healthcare system burden.

Longer patient travel distance is associated with increased non-index readmission after complex aortic surgery

ObjectiveRecently evolving practice patterns in complex aortic surgery have led to regionalization of care within fewer centers in the United States, and thus patients may have to travel farther for complex aortic care. Travel distance has been associated with inferior outcomes after non-vascular surgery, particularly non-index readmission. This study aims to assess the impact of patient travel distance on perioperative outcomes and readmissions after complex aortic surgery. MethodsA retrospective review was conducted of all patients in the Vascular Quality Initiative and Vascular Implant Surveillance and Interventional Outcomes Network databases undergoing complex endovascular aortic repair (EVAR) including internal iliac or visceral vessel involvement, complex thoracic endovascular aortic repair (TEVAR) including zone 0 to 2 proximal extent or branched devices, and complex open abdominal aortic aneurysm (AAA) repair including suprarenal or higher clamp sites. Travel distance was stratified by rural/urban commuting area (RUCA) population-density category. Wilcoxon and χ2 tests were used to assess relationships between travel distance quintiles and baseline characteristics, mortality, and readmission. Travel distance and other factors were included in multivariable Cox models for survival and Fine-Gray competing risk models for freedom from readmission. ResultsBetween 2011 and 2018, 8782 patients underwent complex aortic surgery in the Vascular Quality Initiative and Vascular Implant Surveillance and Interventional Outcomes Network databases, including 4822 complex EVARs, 2672 complex TEVARs, and 1288 complex open AAA repairs. Median travel distance was 22.8 miles (interquartile range [IQR], 8.6-54.8 miles). Median age was 75 years for all distance quintiles, but patients traveling longer distances were more likely female (26.8% in quintile 5 [Q5] vs 19.9% in Q1; P < .001), white (93.8% of Q5 vs 83.8% of Q1; P < .001), to have larger-diameter AAAs (median 59 mm for Q5 vs 55 mm for Q1; P < .001), and to have had prior aortic surgery (20.8% for Q5 vs 5.9% for Q1; P < .001). Overall 30-day readmission was more common at farther distances (18.1% for Q5 vs 14.8% for Q1; P = .003), with higher non-index readmission (11.2% for Q5 vs 2.7% for Q1; P < .001) and conversely lower index readmission (6.9% for Q5 vs 12.0% for Q1; P < .001). Multivariable-adjusted Fine-Gray models confirmed greater hazard of non-index readmission with farther distance, with a Q5 hazard ratio of 3.02 (95% confidence interval, 2.12-4.30; P < .001). Multivariable-adjusted Cox models demonstrated no association between travel distance and long-term survival but found that non-index readmission was associated with increased long-term mortality (hazard ratio, 1.46; 95% confidence interval, 1.20-1.78; P = .0001). ConclusionsPatients traveling farther for complex aortic surgery demonstrate higher non-index readmission, which, in turn, is associated with increased long-term mortality risk. Aortic centers of excellence should consider targeting these patients for more comprehensive follow-up and care coordination to improve outcomes.

Efficacy of cold renal perfusion protection for open complex aortic aneurysm repair: a meta-analysis.

Cold renal perfusion (CRP) with 4°C crystalloid fluids has been described as a method to reduce renal injury during open surgical repair of complex aortic aneurysms (cAAs) (those requiring at least a suprarenal clamp site). We performed a meta-analysis to ascertain whether CRP improves kidney-related outcomes after open surgical cAA repair. Patients of any age or gender who had undergone open surgical repair of cAAs were included. Primary outcomes were the presence of postoperative kidney injury, the need for dialysis and mortality related to kidney injury. We compared patients who were treated with any intraoperative CRP strategy to a control population without CRP. We used a fixed-effects model to analyze derived odds ratios (ORs) and assess heterogeneity. We performed risk of bias analysis to identify potential confounding elements. Among the 935 studies screened, 5 primary articles met the inclusion criteria. Cold renal perfusion significantly reduced postoperative acute kidney injury (OR 0.46 [95% confidence interval 0.32-0.68], Z = 3.98, p = 0.001). Only 1 study included data for the other primary outcomes. The data were considered homogeneous, with Cochrane Q = 0.23 and I 2 of 0%. This meta-analysis showed reduced postoperative acute kidney injury with the use of CRP during open cAA repair. A prospective randomized controlled trial to perform further subgroup analysis and research the various types of CRP solutions may be warranted to identify further possible benefits.

Performance of the Emergency Surgery Score for Predicting Outcomes after Non-Elective Open Aortic Aneurysm Repair

Introduction: The Emergency Surgery Score (ESS) is a reliable tool to predict outcomes after emergency general surgery. The purpose of this study was to assess the performance of ESS for non-elective open aortic aneurysm repair (neOAR) Methods: The American College of Surgeons’ National Surgical Quality Improvement Program database was retrospectively analyzed for patients undergoing neOAR between 2015 and 2020. The performance of the ESS in predicting mortality and other outcomes was assessed using univariate and multivariate logistic regression with receiver operating characteristic analyses. Results: 838 patients underwent neOAR with a 30-day mortality of 23.4%. The ESS correlated with risk of death (C-statistic 0.753), discharge to facility (C-statistic 0.668), postoperative bleeding (C-statistic 0.687), and cardiopulmonary arrest (C-statistic 0.654). A cumulative frequency table of mortality was used to partition patients into quartiles of ESS < 5, ESS of 6, ESS of 7 or 8, and ESS > 9. A Cochran- Armitage test showed linear trend towards adverse outcomes like mortality (p < 0.001), prolonged hospital stay (p = 0.047), prolonged ICU stay (p < 0.001), return to OR (p < 0.001), renal failure (p < 0.001), reintubation (p = 0.009) and colitis (p < 0.001) among the quartiles with increasing ESS. Multivariate analysis including variables like proximal clamp site and hypotension on presentation showed that Quartile 4 (ESS>10) had 3-times higher mortality compared with reference quartile 1 (ESS<5) Conclusion: ESS performance accurately predicts mortality for neOAR procedures. It has the potential to be used for national benchmarking after urgent open aneurysm repair

New Classification for Juxta Renal Aortoiliac Occlusion-based on Imaging for Safe Clamping and Contemporary Surgical Management Results

Objectives: The objective is to decide the site of aortic clamping based on preoperative imaging and intraoperative findings and assess the outcomes on midterm follow-up in patients with juxtarenal aortoiliac occlusion (JRAIO) managed with aortic thromboendarterectomy and bypass grafting. Methods: Forty patients (39 males and one female) with JRAIO were managed with aortobifemoral bypass (ABFB). Two patients required concomitant superior mesenteric artery (SMA) bypass. The aortic clamping site was inter-renal, suprarenal, or supra-celiac, depending on the extent of thrombus relative to the renal artery and SMA ostia. We compared serum creatinine levels with renal ischemic time in the postoperative period. At the mean follow-up of 26.7 months, patients were assessed for graft patency, limb salvage, and survival rate. Results: The mean age of patients was 53.9 years, and 97.5% of patients were heavy smokers. Of the total patients, inter-renal clamping was done in 12.5%, suprarenal clamping in 70%, and supra-celiac clamping in 17.5%. Perioperative morbidity and mortality were 22.5% and 5%, respectively. Five patients with renal ischemic time ≥20 min developed acute kidney injury, showing a significant positive correlation (r = 0.465; P &lt; 0.0001) with clamp time. Postoperative mean serum creatinine values also showed a significant difference (P = 0.0001) between &lt;20 and ≥20 min groups. At follow-up, graft patency and limb salvage rates were 100%, and the survival rate was 97.4%. Conclusion: The risk of atheroembolic renal ischemia in ABFB for JRAIO can be lowered by good preoperative planning and safe intraoperative clamping technique, based on a simple classification for aortic clamping.

Cross-clamp location and perioperative outcomes after open infrarenal abdominal aortic aneurysm repair: A Vascular Quality Initiative® review.

By analyzing national Vascular Quality Initiative (VQI) data for patients undergoing open infrarenal abdominal aortic aneurysms (AAA) repair, we sought to better characterize the effects of different suprarenal clamping positions on postoperative outcomes. We performed a retrospective analysis of a prospectively collected national VQI database for all open infrarenal AAA repairs performed between 2003 and 2017. Patients were initially divided into proximal (above 1 renal, above 2 renals, and supraceliac) and infrarenal clamp groups. Patients were then subdivided into those who underwent surgery between 2003-2010 and those who had surgery between 2011-2017. Univariate followed by multivariate analyses were done to compare the baseline characteristics, preoperative, intraoperative, and postoperative outcomes between the two groups. During the study period, 9068 open AAA repairs were recorded in the VQI; of these, 5043 met the inclusion criteria. Aortic clamp level was infrarenal in 59% (N = 2975), above 1 renal in 15% (N = 735), above both renals in 21% (N = 1053), and supraceliac in 5% (N = 280). The average age was 69 years, and males comprised 73% (N = 3701) of the cohort. The overall 30-day mortality for the entire study group was 2.7%. On univariate analysis, patients who underwent proximal clamping had significantly higher 30-day mortality than those undergoing infrarenal clamping (3.7 vs 2.0%, p < 0.001). After adjusting for preoperative and intraoperative variables, this difference became nonsignificant. On multivariate analysis, clamping above both renals or the celiac artery was associated with an increased occurrence of postoperative myocardial infarction (odds ratio = 1.44, p = 0.037 and odds ratio = 1.78, p = 0.023, respectively). All proximal clamp positions were associated with a significant increase in the incidence of AKI and renal failure requiring dialysis. There was no significant difference when looking at overall survival times comparing the suprarenal and infrarenal clamp position groups (p = 0.1). Patients who underwent surgery in the latter half of the study period had longer intraoperative renal ischemia time, increased in estimated blood loss, and longer total procedure time. Suprarenal clamping, at any level, was associated with an increased risk of AKI and renal replacement therapy. Clamping above both renal and celiac arteries was associated with increased cardiac morbidity. Perioperative and long-term mortality was unaffected by clamp level. Patients operating in the latter half of the study had increased estimated blood loss, renal ischemia time, and operative time, which may reflect decreased training in open AAA repair. During open AAA repair, the proximal clamp site should be chosen based on anatomic considerations and not a perceived perioperative mortality benefit. Proximal aortic clamping should always be performed at the safest, distal-most level to reduce cardiac morbidity and the risk of postoperative dialysis.

A retroperitoneal operative approach is associated with improved perioperative outcomes compared with a transperitoneal approach in open repair of complex abdominal aortic aneurysms

ObjectiveSeveral studies have demonstrated the advantages of a retroperitoneal (RP) vs a transperitoneal (TP) approach during open repair of infrarenal abdominal aortic aneurysms (AAAs). We compared the outcomes after open repair of complex AAAs (cAAAs) using an RP vs a TP approach and evaluated the relative use of these approaches over time. MethodsWe identified all patients who had undergone open intact cAAA repair in the Vascular Quality Initiative from 2003 to -2019 and created 1:1-propensity score-matched cohorts stratified by the operative approach (RP vs TP). The primary outcome was perioperative mortality. The secondary outcomes included perioperative complications and approach usage over time. To create 1:1 propensity score-matched cohorts, the patients were matched for demographics, comorbidities, and anatomic and/or intraoperative characteristics, including proximal clamp site and renal revascularization. The approach usage over time was determined by plotting the proportion of RP usage over time for the overall open cAAA cohort and subgroups of repairs using a supraceliac cross clamp, repair with concomitant renal revascularization, and repairs performed at high-volume centers (highest quintile, >11 cases annually). ResultsOf a total of 4613 patients, 2843 (62%) had undergone open cAAA repair using the TP approach and 1770 (38%) using the RP approach. Of the 1256 matched pairs, the RP approach was associated with lower risk of perioperative mortality compared with the TP approach (3.9% vs 6.8%; relative risk [RR], 0.57; 95% confidence interval [CI], 0.41-0.80; P = .001). Furthermore, the RP approach was associated with a lower risk of cardiac complications (7.2% vs 9.6%; RR, 0.75; 95% CI, 0.58-0.98), bowel ischemia (3.1% vs 5.4%; RR, 0.56; 95% CI, 0.39-0.84), and postoperative dialysis (3.3% vs 5.5%; RR, 0.59; 95% CI, 0.41-0.87). Overall, the proportion of patients who had undergone repair via an RP approach became lower over time (−1.0%/y; 95% CI, −1.5 to −0.5; P < .001). A similar trend in the decrease was found for the patients who had undergone repair with a supraceliac clamp (−2.3%/y; 95% CI, −3.6 to −1.0; P < .001) and in the high-volume hospitals (−2.1%/y; 95% CI, −3.4 to −0.8; P = .001), although no statistically significant decrease in RP usage was found for the patients who had undergone concomitant renal revascularization (−0.9%/y; 95% CI, −2.6 to 0.8; P = .28). ConclusionsFor open cAAA repair, an RP approach was associated with lower perioperative mortality and complications compared with a TP approach. However, the relative usage of the RP approach has been decreasing over time. An increased adoption of the RP approach, when appropriate, might lead to improved outcomes with open cAAA repair.

Evaluating proximal clamp site and intraoperative ischemia time among open repair of juxtarenal aneurysms

BackgroundThe proportion of open aneurysm repairs requiring at least a suprarenal clamp has increased in the past few decades, partly owing to preferred endovascular approaches for most patients with infrarenal aneurysms, suggesting that the management of aortic clamp placement has become even more relevant. This study evaluated the association between the proximal clamp site and intraoperative ischemia times with postoperative renal dysfunction and mortality. MethodsWe used the Vascular Quality Initiative to identify all patients undergoing open repairs of elective or symptomatic juxtarenal AAAs from 2004 to 2018 and compared outcomes by clamp site: above one renal artery, above both renal arteries (suprarenal), or above the celiac trunk (supraceliac). Outcomes evaluated included acute kidney injury (AKI), new-onset renal failure requiring renal replacement therapy (RRT), 30-day mortality, and 1-year mortality. We used multilevel logistic regressions and Cox proportional hazards models, clustered at the hospital level, to adjust for confounding. ResultsWe identified 3976 patients (median age, 71 years; 70% male; 8.2% non-Caucasian), with a median aneurysm diameter of 5.9cm (interquartile range [IQR], 5.4-6.8 cm). Proximal clamp sites were above one renal artery (31%), suprarenal (52%), or supraceliac (17%). The rates of unadjusted outcomes were 20.5% for AKI, 4.1% for new-onset RRT, 4.9% for 30-day mortality, and 8.3% for 1-year mortality. On adjusted analyses, independent of ischemia time, suprarenal clamping relative to clamping above a single renal artery had higher odds of postoperative AKI (adjusted odds ratio [aOR], 1.50; 95% confidence interval; 95% CI, CI, 1.28-1.75), but similar odds for new-onset RRT (aOR, 1.27; 95% CI, 0.79-2.06) and 30-day mortality (aOR, 1.12; 95% CI, 0.79-1.58) and hazards for 1-year mortality (adjusted hazard ratio, 1.12; 95% CI, 0.86-1.45). However, every 10 minutes of prolonged intraoperative ischemia time was associated with an increase in odds or hazards ratio of postoperative AKI by 7% (IQR, 3%-11%), new-onset RRT by 11% (IQR, 4%-17%), 30-day mortality by 11% (IQR, 6%-17%), and 1-year mortality by 7% (IQR, 2%-13%). Patients with more than 40 minutes of ischemia time had notably higher rates of all four outcomes. ConclusionsSuprarenal clamping relative to clamping above a single renal artery was associated with AKI, but not new-onset RRT or 30-day mortality. However, the intraoperative renal ischemia time was independently associated with all four postoperative outcomes. Although further studies are warranted, our findings suggest that an expeditious proximal anastomosis creation is more important than trying to maintain clamp position below one renal artery, suggesting that suprarenal clamping may be the best strategy for open AAA repair when needed to efficiently perform the proximal anastomosis.

Early and midterm outcomes following open surgical conversion after failed endovascular aneurysm repair from the "Italian North-easT RegIstry of surgical Conversion AfTer Evar" (INTRICATE).

To report the early and mid-term outcomes following open surgical conversion (OSC) after failed endovascular aortic repair (EVAR) using data from a multicentric registry. A retrospective study was carried out on consecutive patients undergoing OSC after failed EVAR at eight tertiary vascular units from the same geographic area in the North-East of Italy, from April 2005 to November 2019. Study endpoints included early and follow-up outcomes. A total of 144 consecutive patients were included in the study. Endoleaks were the most common indication for OSC (50.7%), with endograft infection (24.6%) and occlusion (21.9%) being the second most prevalent causes. The overall rate of 30-day all-cause mortality was 13.9% (n= 20); 32 patients (22.2%) experienced at least one major complication. Mean length of stay was 13± 12.7days. On multivariate logistic regression, age (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.01-1-19; P= .02), renal clamping time (OR, 1.07; 95% CI, 1.02-1.13; P= .01), and suprarenal/celiac clamping (OR, 6.66; 95% CI, 1.81-27.1; P= .005) were identified as independent predictors of perioperative major complications. Age was the only factor associated with perioperative mortality at 30days. Renal clamping time >25minutes had sensitivity of 65% and specificity of 70% in predicting the occurring of major adverse events (area under the curve, 0.72; 95% CI, 0.61-0.82). At 5years, estimated survival was significantly lower for patients treated due to aortic rupture/dissection (28%; 95% CI, 13%-61%), compared with patients in whom the indication for treatment was endoleak (54%; 95% CI, 40%-73%), infection (53%; 95% CI, 30%-94%), or thrombosis (82%; 95% CI, 62%-100%; P= .0019). Five-year survival rates were significantly lower in patients who received emergent treatment (28%; 95% CI, 14%-55%) as compared with those who were treated in an urgent (67%; 95% CI, 48%-93%) or elective setting (57%; 95% CI, 43%-76%; P= .00026). Subjects who received suprarenal/celiac (54%; 95% CI, 36%-82%) or suprarenal (46%; 95% CI, 34%-62%) aortic cross-clamping had lower survival rates at 5years than those whose aortic-cross clamp site was infrarenal (76%; 95% CI, 59%-97%; P= .041). Using multivariate Cox proportional hazard, older age and emergency setting were independently associated with higher risk for overall 5-year mortality. OSC after failed EVAR was associated with relatively high rates of early morbidity and mortality, particularly for emergency setting surgery. Endoleaks with secondary sac expansion were the main indication for OSC, and suprarenal aortic cross-clamping was frequently required. Endograft infection and emergent treatment remained associated with poorer short- and long-term survival.

The Association Between Preoperative Independent Ambulatory Status and Outcomes After Open Abdominal Aortic Aneurysm Repairs

Preoperative functional status is appreciated as a key determinant of decision-making when evaluating patients for complex elective surgeries. We used the Vascular Quality Initiative to analyze the effect of being able to independently ambulate on outcomes after open abdominal aortic aneurysm (AAA) repairs. We identified all patients who underwent elective or urgent open AAA repairs from January 2013 to August 2019 in the Vascular Quality Initiative registry. We recorded demographic variables, comorbidities, and operative factors such as approach, operative ischemia time, proximal clamp site, and presence of iliac aneurysms. Short-term and long-term outcomes included 30-day mortality, any perioperative complications, failure to rescue (defined as death after a complication), and 1-year all-cause mortality. We dichotomized patients based on their ability to independently ambulate (Ambulatory) or inability to ambulate independently (Non-Ambulatory) and used both multivariable logistic regressions and cox-proportional hazards models to evaluate outcomes. Of 5,371 patients, 328 (6.1%) could not ambulate independently and were more likely to be older (median age 69 vs. 72), female (25% vs. 38%), and have greater comorbidities. Overall outcomes were: 4.3% for 30-day mortality, 38.7% for complications, 10.2% for failure-to-rescue, and 6.9% for 1-year mortality. Univariate analysis showed higher rates of all adverse outcomes in non-ambulatory patients. On adjusted analysis, non-ambulatory patients had increased odds of complications by 46% (OR 1.46 [95%-CI 1.11-1.91]) and 1-year mortality by 46% (HR 1.46 [95%-CI 1.06-1.99]), but not failure to rescue (OR 1.05 [95%-CI 0.67-1.62]) or 30-day mortality (OR 1.22 [95%-CI 0.82-1.81]). Increased hospital volume, age, and increased operative renal ischemia time were independently associated with adverse outcomes. Non-ambulatory status was observed in a small percentage of patients undergoing open AAA repair but was associated with higher rates of post-operative complications and 1-year mortality. Ambulatory capacity is one of the key determinants of outcomes following open AAA repair. In patients with poor ambulatory function, a conservative approach is highly recommended over invasive open surgical intervention.

Efficacy of Cold Renal Perfusion Protection for Open Complex Aortic Aneurysm Repair: A Meta-Analysis

Open surgical repair of complex aortic aneurysms has been associated with a risk of acute kidney injury, leading to significant morbidity and mortality. Cold renal perfusion (CRP) with 4°C crystalloid fluids during open repair is a method to reduce renal injury during repair. A meta-analysis assessing CRP for open repair of complex aortic aneurysms was performed. Complex aneurysms were defined as those requiring at least a suprarenal clamp site and included juxtarenal, suprarenal, and thoracoabdominal aortic aneurysms.

Open repair versus EVAR with parallel grafts in patients with juxtarenal abdominal aortic aneurysm excluded from fenestrated endografting

We compared the outcomes of open surgical repair (OSR) versus endovascular aortic repair (EVAR) with parallel graft technique (PG) in patients with juxtarenal abdominal aortic aneurysm (JAAA) excluded from fenestrated endovascular aortic repair (FEVAR) due to clinical, anatomical, technical or manufacturing time reasons. A single-center analysis of consecutive patients who underwent elective and urgent (within 24-48 hours) repair of JAAA from January 2010 to January 2019 was performed. Two groups were compared: patients excluded from FEVAR and respectively treated by OSR or by PG for JAAA. Perioperative clinical, anatomic and operative data were collected in a dedicated database. The endpoints were primary technical success, changes in renal function, early and long-term mortality, freedom from aortic related reinterventions (ARRs) and aortic related mortality (ARM). Overall, 118 consecutive patients were treated for JAAA, 32 of whom (27.1%) with FEVAR. Eighty-six patients were enrolled in the study (OSR group, N.=61; PG group, N.=25). The mean age was 77.4±6.5 years for PG group and 71.1±6.7 years for OSR group (P=0.0001); the average comorbidity score of the Society for Vascular Surgery was higher for patients treated by PG (10.2±4.8 vs. 5.5±0.4, P=0.0001), with no differences for hypertension and renal score. After propensity score matching, 42 patients (27 OSR, 15 PG) without differences in the preoperative risk factors were selected. Conical shape and neck mural thrombus were respectively more represented in the OSR group (95.1% vs. 56.0%; 63.9% vs. 36.0%). Aortic clamp site was supraceliac for 12 patients (19.7%), suprarenal for 21 (34.4%) and trans-renal for 28 patients (45.9%). In the PG group, 16 patients (64%) were treated with a single renal chimney. Primary technical success was similar in the two groups (100.0% vs. 92.0%, P=0.08), with a higher rate of procedure achieved by assisted technical success for the PG group after propensity score matching analysis (20.0% vs. 0%, P=0.04). Deterioration of renal function occurred for both groups of patients, with a significant creatinine increasing 12 months after surgery in the PG group compared with OSR group (1.72±0.66 vs. 1.18±0.40, P=0.006). Multiple logistic regression shows no independent predictor of peri-operative medical complication among demographics and pre-operative relevant clinical factors between the two cohorts. No difference in terms of early mortality was observed between the groups (1.6% vs. 0%, P=1.00). At 5 years, overall survival was lower for patients treated by PG (53.5% vs. 70.2%, P=0.007), such as freedom from ARRs (64.6 vs. 90.5%, P=0.03). Freedom from ARM at 5 years did not show significant differences among the two groups (100% vs. 98.4%, P=1.00). PG represents a feasible procedure for patients excluded from FEVAR due to clinical, anatomical, technical or device manufacturing time reasons, ensuring low rates of ARM. However, ARRs during the follow-up remain the Achilles heel of this technique. OSR is still the most durable procedure in the endovascular era, allowing the treatment of proximal "hostile necks" with low rates of reoperation and a similar impact on the renal function compared to PG.

Decreased transfusion requirements with use of acute normovolemic hemodilution in open aortic aneurysm repair

ObjectiveAcute normovolemic hemodilution (ANH) is an operative blood conservation technique involving the removal and storage of patient blood after the induction of anesthesia, with maintenance of normovolemia by crystalloid and/or colloid replacement. Developed and used predominately in cardiac surgery, ANH has been applied to the vascular surgery population. However, data regarding the effects on transfusion requirements in this population are limited. The objective of the present study was to compare the transfusion requirements and coagulopathy for patients who had undergone open abdominal aortic aneurysm repair (oAAAR) using ANH to those for patients who had received only product replacements, as clinically indicated. MethodsWe performed a retrospective review of patients who had undergone elective oAAAR at a quaternary aortic referral center from 2017 to 2019. Those eligible for ANH, with no active cardiac ischemia, no valvular disease, normal left ventricular and right ventricular function, chronic kidney disease stage <3, hematocrit >38%, and a normal coagulation profile were included in the present study. Patient demographics and characteristics and operative variables, including aneurysm extent, clamp site, visceral and renal ischemia time, operative time, and transfusion requirements, were collected. Postoperative morbidity, mortality, and length of stay were analyzed. The patients with and without ANH were matched and compared. Continuous measures were analyzed using Wilcoxon rank sum tests and t tests. ResultsDuring the study period, 209 oAAARs had been performed. Of the 209 patients, 76 had met the inclusion criteria. Of these 76 patients, 27 had undergone ANH and 49 had not. The patients with ANH had required fewer PRBC transfusions intraoperatively (median, 0 U; interquartile range [IQR], 0-1 U; median, 1 U; IQR, 0-2 U; P = .02), at 24 hours (median, 0 U; IQR, 0-1 U; vs median, 1 U; IQR, 0-2 U; P = .008), at 48 hours (median, 0 U; IQR, 0-1 U; vs median, 1 U; IQR, 0-2; P = .007), and throughout the admission (median, 0 U; IQR, 0-1 U; vs median, 2 U; IQR, 0-2 U; P = .011). No difference was found in the number of intraoperative platelet or cryoprecipitate transfusions. At 48 hours, the ANH group had had significantly greater platelet counts (142 ± 35.8 × 103/μL vs 124 ± 37.6 × 103/μL; P = .044), lower partial thromboplastin time, and lower international normalized ratio. No difference in myocardial infarction, return to the operating room, or mortality (one death overall). The ANH patients had a shorter length of stay (7.0 ± 2.7 vs 8.8 ± 4.8 days; P = .041). ConclusionsThe use of ANH during oAAAR resulted in fewer intraoperative and postoperative PRBC transfusions with improved coagulation parameters and a shorter hospital length of stay.

Association between hospital volume and failure-to-rescue for open repairs of juxtarenal aneurysms

BackgroundA nationwide variation in mortality stratified by hospital volume exists after open repair of complex abdominal aortic aneurysms (AAAs). In the present study, we assessed whether the rates of postoperative complications or failure-to-rescue (defined as death after a major postoperative complication) would better explain the lower mortality rates among higher volume hospitals. MethodsUsing the 2004 to 2018 Vascular Quality Initiative database, we identified all patients who had undergone open repair of elective or symptomatic AAAs, in which the proximal clamp sites were at least above one renal artery. We divided the patients into hospital quintiles according to the annual hospital volume and compared the risk-adjusted outcomes. Multivariable logistic regression, adjusted for patient characteristics, operative factors, and hospital volume, was used to evaluate three outcomes: 30-day mortality, overall complications, and failure-to-rescue. ResultsWe identified 3566 patients who had undergone open repair of elective or symptomatic complex AAAs (median age, 71 years; 29% women; 4.1% black; 48% Medicare insurance). The unadjusted rates of 30-day postoperative mortality, overall complications, and failure-to-rescue were 5.0%, 44%, and 10%, respectively. Common complications included renal dysfunction (25%), cardiac dysrhythmia (14%), and pneumonia (14%), with the specific failure-to-rescue rate ranging from 12% to 22%. On adjusted analysis, the risk-adjusted mortality rate was 2.5 times greater for the lower volume hospitals relative to the higher volume hospitals (7.4% vs 3.0%; P < .01). Although the risk-adjusted complication rates were similar between these hospital groups (30% vs 27%; P = .06), the failure-to-rescue rate was 2.3 times greater for the lower volume hospitals relative to the higher volume hospitals (6.3% vs 2.7%; P = .02). ConclusionsHigher volume hospitals had lower mortality rates after open repair of complex AAAs because they were better at the “rescue” of patients after the occurrence of postoperative complications. Both an understanding of the clinical mechanisms underlying this association and the regionalization of open repair might improve patient outcomes.

The variable impact of aneurysm size on outcomes after open abdominal aortic aneurysm repairs

ObjectivePrevious studies evaluating the association between abdominal aortic aneurysm (AAA) size with postoperative outcomes after open repairs seldom accounted for renal or visceral artery involvement, proximal clamp site, intraoperative renal ischemia time, and hospital volume. This study examined the association between aneurysm size with outcomes after open repairs. MethodsWe identified patients who underwent open repairs of infrarenal versus juxtarenal nonruptured AAAs, defined by proximal clamp site, in the 2004-2019 Vascular Quality Initiative. Outcomes included 30-day mortality, postoperative complications, failure to rescue, and 1-year mortality. Multivariable logistic regressions adjusted for patient characteristics, operative factors, hospital volume, and hospital clustering. ResultsWe identified 8011 patients (54% infrarenal, 46% juxtarenal). The median aneurysm size did not differ between infrarenal versus juxtarenal aneurysms (5.7 cm vs 5.9 cm; P = .12). For infrarenal aneurysms, every 1-cm increase in size increase the adjusted odds ratio (OR) or hazard ratio (HR) of 30-day mortality by 18% (OR, 1.18; 95% CI, 1.06-1.31), failure to rescue by 20% (OR, 1.20; 95% CI, 1.06-1.34), 1-year mortality by 18% (HR, 1.18; 95% CI, 1.10-1.26), but not complications (OR, 1.03; 95% CI, 0.98-1.07). For juxtarenal aneurysm, larger aneurysm sizes were not associated with any outcome. Proximal clamp site, ischemia time, and volume were associated with outcomes. ConclusionsThe association between AAA size and outcomes matters less with renal and visceral artery aneurysmal involvement, having important implications for surgical decision-making, operative planning, and patient counseling.

The Association Between Hospital Volume and Failure-to-rescue for Open Repairs of Juxtarenal Aneurysms

Higher-volume hospitals have lower mortality rates after open repairs of complex abdominal aortic aneurysms (AAAs). However, the clinical mechanisms underlying this association remain elusive. We assessed whether rates of postoperative complications versus failure to rescue (defined as death after a major postoperative complication) better explained lower mortality rates among higher-volume hospitals after open repairs of complex AAAs. Using the 2004 to 2018 Vascular Quality Initiative, we identified all patients who underwent open repairs of complex AAAs, where the proximal clamp site was above at least one renal artery. After dividing patients into quintiles by annual hospital volume, we compared risk-adjusted rates of 30-day postoperative mortality, complications, and failure to rescue between the lowest volume and highest volume hospitals. Multivariable logistic regressions adjusted for clinical and intraoperative factors (ie, proximal clamp site, ischemia time, iliac aneurysmal disease), and hospital clustering. We identified 3566 patients (median age, 71 years; 81% male; 92% Caucasian; median aneurysm size, 5.9 cm) undergoing open repairs of complex AAAs. The risk-adjusted mortality rate was 2.5 times greater among lower volume hospitals relative to higher volume hospitals (7.4% vs 3.0%; P < .01). While risk-adjusted complication rates were respectively similar (29.5% vs 26.9%; P = .06), risk-adjusted failure-to-rescue rates were 2.3 times greater among lower volume hospitals relative to their higher volume counterparts (6.3% vs 2.7%; P = .02) (Table). The most common postoperative complications included renal dysfunction (25%), cardiac dysrhythmia (14%), and pneumonia (14%), with their specific rates of failure to rescue varying from 12% to 22%. Higher volume hospitals have lower mortality rates after open repairs of complex AAAs because they better “rescue” patients from complications, relative to their lower volume counterparts. Understanding the clinical mechanisms underlying this association, from macroscopic hospital factors to communication and culture, in addition to the regionalization of open repairs of complex AAAs, may improve patient outcomes.TableMultivariate logistic regressions assessing the association between hospital volume and all three outcomesHigh-volume hospitalsLow-volume hospitalsaOR (95%-CI)aP valueaMortality3.0%7.4%2.51 (1.42-4.42)<.01Complications27.1%29.2%1.31 (0.91-1.90)0.15Failure-to-rescue2.7%6.3%2.30 (1.16-4.57)0.02aAdjusted for hospital volume quintiles, patient age, gender, race, insurance, BMI, smoking history, aneurysm diameter, operative approach, intraoperative ischemia time, prior aortic surgery, presence of iliac aneurysms, comorbidities (COPD, CKD, heart disease, DM, PVD, carotid artery stenosis or endarterectomy) and hospital-level clustering. Reference: high-volume hospitals. Open table in a new tab