Fifteen-year, single-center experience with in situ reconstruction for infected native aortic aneurysms.

OBJECTIVE: The purpose of the present study was to evaluate the survival and freedom from reinfection for patients with infected native aortic aneurysms (INAAs) treated with in situ revascularization (ISR), using either open surgical repair (OSR) or endovascular aneurysm repair (EVAR), and to identify the predictors of outcome. METHODS: Patients with INAAs who had undergone ISR from January 2005 to December 2020 were included in the present retrospective single-center study. The diagnosis of INAAs required a combination of two or more of the following criteria: (1) clinical presentation, (2) laboratory results, (3) imaging findings, and (4) intraoperative findings. The primary endpoint was 30-day mortality. The secondary endpoints were in-hospital mortality, estimated survival, patency, and freedom from reinfection using the Kaplan-Meier method. The predictive factors for adverse outcomes were evaluated using the Mann-Whitney U test or the Fisher exact test and multivariate regression analysis. RESULTS: A total of 65 patients (53 men [81.5%]; median age, 69.0 years; interquartile range, 61.5-75.0 years) were included, 31 (47.7%) were immunocompromised, 60 were symptomatic (92.3%), and 32 (49.2%) had presented with rupture, including 3 aortocaval fistulas (4.6%) and 12 aortoenteric fistulas (18.5%). The most common location was infrarenal (n = 39; 60.0%). Of the 65 patients, 55 (84.6%) had undergone primary OSR with ISR, 3 (4.6%) had required EVAR as a bridge to OSR, and 8 (12.3%) had undergone EVAR as definitive treatment. The approach was a midline laparotomy for 44 patients (67.7%), mostly followed by reconstruction and aortic-aortic bypass (n = 28; 40.6%) and the use of a silver and triclosan Dacron graft (n = 30; 43.5%). Causative organisms were identified in 55 patients (84.6%). The 30-day and in-hospital mortality rates were 6.2% (n = 4) and 10.8% (n = 7). The median follow-up was 33.5 months (interquartile range, 13.6-62.3 months). The estimated 1- and 5-year survival rates were 79.7% (95% confidence interval [CI], 67.6%-87.7%) and 67.4% (95% CI, 51.2%-79.3%). The corresponding freedom from reinfection rates were 92.5% (95% CI, 81.1%-97.1%) and 79.4% (95% CI, 59.1%-90.3%). On multivariate analysis, in-hospital mortality increased with uncontrolled sepsis (P < .0001), rapidly expanding aneurysms (P = .008), and fusiform aneurysms (P = .03). The incidence of reinfection increased with longer operating times (P = .009). CONCLUSIONS: The selective use of ISR and OSR combined with targeted antimicrobial therapy functioned reasonably well in the treatment of INAAs, although larger, prospective, multicenter studies with appropriately powered comparative cohorts are necessary to confirm our findings and to determine the best vascular substitute and precise role of EVAR as a bridge to OSR or definitive treatment.

Retrospective Study Comparing WBC scan and 18F-FDG PET/CT in Patients with Suspected Prosthetic Vascular Graft Infection.

OBJECTIVES: Prosthetic vascular graft infections (PVGIs) are associated with high mortality rates. To improve treatment outcome, an early and definite diagnosis is critical, and current diagnostic criteria are often insufficient. The accuracy of 2-deoxy-2-[fluorine-18]-fluoro-d-glucose positron emission tomography integrated with computed tomography (18F-FDG PET/CT) and white blood cell (WBC) scan for the diagnosis of PVGI were compared. METHODS: A retrospective single centre study was conducted on patients undergoing WBC scan and 18F-FDG PET/CT for a suspected PVGI between April 2013 and June 2016 at the Bordeaux University Hospital, France. The diagnostic value of both imaging tests was assessed for all grafts, using receiver operating characteristic (ROC) curve analysis. Images were independently interpreted by two nuclear medicine physicians blinded to the patients' clinical and other imaging data. RESULTS: Thirty-nine patients were included, of whom 15 had PVGI. Antibiotic treatment was started before nuclear imaging for 16 patients, including nine patients with a PVGI. The 96 grafts of these patients were analysed, and 19 were infected. The diagnostic value of the WBC scan was significantly higher than 18F-FDG PET/CT (ROC AUC = 0.902, 95% CI 0.824-0.980, and 0.759, CI 95% (0.659-0.858), respectively, p = .0071). Interobserver agreement was good for 18F-FDG PET/CT and excellent for WBC scan (kappa value of 0.76, 95% CI 0.62-0.9, and 0.97, 95% CI 0.92-1, respectively). Only one patient had a false negative 18F-FDG PET/CT result under antibiotic therapy. CONCLUSION: The WBC scan has a better diagnostic value than 18F-FDG PET/CT for PVGI diagnosis.

In vitro Evidence of Improved Antimicrobial Efficacy of Silver and Triclosan Containing Vascular Grafts Compared with Rifampicin Soaked Grafts.

OBJECTIVES: The aim was to compare the antimicrobial efficacy of four different grafts: a standard graft (Intergard, IG), an IG graft soaked in rifampicin (IGrif), a silver impregnated graft (Intergard Silver, IGS), and a silver + triclosan impregnated graft (Intergard Synergy, IGSy). METHODS: This was a seven day in vitro study. The IG, IGrif, IGS, and IGSy grafts were each contaminated separately with the following microorganisms: Staphylococcus epidermidis, Methicillin resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans from both clinical and American Type Culture Collection (ATCC) origins. The in vitro antimicrobial efficacy was evaluated by time to kill assays at T0, T24h, T48h, T72h, and T168h. Bactericidal activity was defined as >3 log10 reduction factor (logRF). Additionally, Rifampicin, triclosan and silver resistance development were screened. RESULTS: As anticipated for the non-antimicrobial IG, all microorganism strains proliferated. The IGSy and the IGS showed a seven day bactericidal efficacy (>3 logRF) for all tested microorganisms. This efficacy was confirmed at all time points for IGSy only, demonstrating faster bactericidal efficacy than IGS. The IGrif demonstrated a seven day bactericidal efficacy against the ATCC MRSA only, while showing no activity against C. albicans and ATCC E. coli. Regarding ATCC S. epidermidis, clinical MRSA and clinical E. coli, IGrif, although bactericidal at earlier time points, lost its antimicrobial efficacy at seven days leading to the emergence of rifampicin resistant mutants in four of six, two of six, and two of six assays, respectively. Mutant strains were also detected in ATCC MRSA in one of six assays. No triclosan or silver resistance has emerged at T7days. CONCLUSION: For all microorganisms tested, the Synergy graft combining silver with triclosan demonstrated a more sustainable and efficient seven day antimicrobial activity than the rifampicin soaked graft. The emergence of rifampicin resistant mutants suggests preference for a Synergy graft over a graft soaked in rifampicin, to prevent or treat an infection when a biological solution is not feasible.

Comparison of Genus Specific PCR and Culture with or without Sonication for Microbiological Diagnosis of Vascular Graft Infection.

OBJECTIVES: Vascular graft infections (VGIs) are severe and require prolonged adequate antimicrobial therapy. However, up to 45% of conventional cultures are negative. Sonication and genus specific PCRs for microbiological diagnosis of VGI was evaluated. METHODS: Samples were prospectively obtained from explanted vascular grafts in Bordeaux University Hospital. Conventional bacterial cultures with and without prior sonication of samples were performed. A genus specific PCR assay panel, targeting the most frequent bacteria involved in VGI (Staphylococcus, Streptococcus, Enterococcus, and Enterobacteriaceae), was also applied to sonicate fluids. The performance of these three diagnostic strategies was compared. RESULTS: Forty-five patients (118 samples) were included between July 2014 and October 2015. Six patients had no infection and 39 had a VGI. Sensitivities of graft culture, sonicate fluid culture, and genus specific PCR were 85.7%, 89.7%, and 79.5%, respectively. Specificities were 100%, 100%, and 83.3%, respectively. Sonicate fluid culture was positive for five graft samples (from four patients) with negative culture without sonication. Four VGIs were detected by PCR only (3 patients had previously received antibiotics). For 15 patients with positive graft cultures, PCR identified at least one additional bacterium compared with culture, thus 30 additional bacteria for all included patients. By combining sonicate fluid culture and PCR, a microbiological diagnosis was obtained for all patients with VGI. CONCLUSIONS: There was no statistical difference between performances of culture with and without sonication and genus specific PCR. However, combining sonicate fluid cultures and PCR may be the best strategy for microbiological diagnostic of VGI.

Automated, continuous and non-invasive assessment of pulse pressure variations using CNAP® system.

Non-invasive respiratory variations in arterial pulse pressure using infrared-plethysmography (PPVCNAP) are able to predict fluid responsiveness in mechanically ventilated patients. However, they cannot be continuously monitored. The present study evaluated a new algorithm allowing continuous measurements of PPVCNAP (PPVCNAPauto) (CNSystem, Graz, Austria). Thirty-five patients undergoing vascular surgery were studied after induction of general anaesthesia. Stroke volume was measured using the VigileoTM/FloTracTM. Invasive pulse pressure variations were manually calculated using an arterial line (PPVART) and PPVCNAPauto was continuously displayed. PPVART and PPVCNAPauto were simultaneously recorded before and after volume expansion (500 ml hydroxyethylstarch). Subjects were defined as responders if stroke volume increased by ≥15 %. Twenty-one patients were responders. Before volume expansion, PPVART and PPVCNAPauto exhibited a bias of 0.1 % and limits of agreement from -7.9 % to 7.9 %. After volume expansion, PPVART and PPVCNAPauto exhibited a bias of -0.4 % and limits of agreement from -5.3 % to 4.5 %. A 14 % baseline PPVART threshold discriminated responders with a sensitivity of 86 % (95 % CI 64-97 %) and a specificity of 100 % (95 % CI 77-100 %). Area under the receiver operating characteristic (ROC) curve for PPVART was 0.93 (95 % CI 0.79-0.99). A 15 % baseline PPVCNAPauto threshold discriminated responders with a sensitivity of 76% (95 % CI 53-92 %) and a specificity of 93 % (95 % CI 66-99 %). Area under the ROC curves for PPVCNAPauto was 0.91 (95 % CI 0.76-0.98), which was not different from that for PPVART. When compared with PPVART, PPVCNAPauto performs satisfactorily in assessing fluid responsiveness in hemodynamically stable surgical patients.

Should white blood cell scan be replaced by (18)F-FDG PET-CT in the diagnosis of prosthetic vascular graft infection?

Diagnosis of prosthetic vascular graft infection (PVGI) is a clinical challenge requiring accurate diagnostic methods for their optimal management. A 65-year-old patient with suspected PVGI was explored by fluorodeoxyglucose positron emission tomography combined with computed tomography ((18)F-FDG PET-CT) for pretreatment staging. Standard imaging was unrevealing but PET images showed multiple foci with increased uptake suggesting prosthetic infection. While routine results from the diagnostic laboratory were negative, prosthesis sonication before standard culture revealed the same bacterium as a culture of preoperative lymphocele aspiration. (18)F-FDG PET-CT and preliminary sonication of the prosthetic graft could be very helpful in the diagnosis of PVGI especially for highlighting biofilm bacteria.

18F-FDG PET-CT in suspected prosthetic vascular graft infection.

BACKGROUND: Diagnosis of prosthetic vascular graft infections is a clinical challenge, and surgical therapy is associated with comorbidity. Therefore, accurate diagnostic methods are required for their optimal management. METHODS: A 61-year-old-patient presented with erysipelas of the right lower limb 7 months after receiving a hybrid femoropopliteal bypass composed of a saphenous vein distally and external supported polytetrafluoroethylene proximally. He had been first treated for suspicious of septic arterial thrombosis or false aneurysm with antibiotics. A computed tomography (CT) angiogram was performed to detect any potential infection of the bypass and to explore erysipelas. It revealed a subcutaneous infiltration and an infiltration of the right groin but no anastomotic pseudoaneurysm or thrombosis of the bypass. The 2-[18F]-fluoro-2-desoxy-d-glucose positron emission tomography (18F-FDG PET) evidenced a significant uptake of cutaneous and subcutaneous tissue but no uptake on the vascular prosthetic graft. Therefore, the bypass was considered as noninfected and antibiotics were continued for 3 months. A physical examination on antibiotic cessation revealed a nonerythematous thigh with a C-reactive protein level significantly decreased to 36 mg/L and a normal white blood cell count. A PET scan confirmed this clinical improvement as attested by a dramatically decreased uptake of cutaneous and subcutaneous tissues and still no uptake of the graft. CONCLUSIONS: In conclusion, this case highlights the role that 18F-FDG PET-CT may play in excluding suspected prosthetic graft infection, thanks to its high sensitivity and in avoiding needless revision surgery with subsequent comorbidities.

The ability of pulse pressure variations obtained with CNAP™ device to predict fluid responsiveness in the operating room.

BACKGROUND: Respiratory-induced pulse pressure variations obtained with an arterial line (ΔPP(ART)) indicate fluid responsiveness in mechanically ventilated patients. The Infinity® CNAP™ SmartPod® (Dräger Medical AG & Co. KG, Lübeck, Germany) provides noninvasive continuous beat-to-beat arterial blood pressure measurements and a near real-time pressure waveform. We hypothesized that respiratory-induced pulse pressure variations obtained with the CNAP system (ΔPP(CNAP)) predict fluid responsiveness as well as ΔPP(ART) predicts fluid responsiveness in mechanically ventilated patients during general anesthesia. METHODS: Thirty-five patients undergoing vascular surgery were studied after induction of general anesthesia. Stroke volume (SV) measured with the Vigileo™/FloTrac™ (Edwards Lifesciences, Irvine, CA), ΔPP(ART), and ΔPP(CNAP) were recorded before and after intravascular volume expansion (VE) (500 mL of 6% hydroxyethyl starch 130/0.4). Subjects were defined as responders if SV increased by ≥15% after VE. RESULTS: Twenty patients responded to VE and 15 did not. The correlation coefficient between ΔPP(ART) and ΔPP(CNAP) before VE was r = 0.90 (95% confidence interval [CI] = 0.84-0.96; P < 0.0001). Before VE, ΔPP(ART) and ΔPP(CNAP) were significantly higher in responders than in nonresponders (P < 0.0001). The values of ΔPP(ART) and ΔPP(CNAP) before VE were significantly correlated with the percent increase in SV induced by VE (respectively, r(2) = 0.50; P < 0.0001 and r(2) = 0.57; P < 0.0001). Before VE, a ΔPP(ART) >10% discriminated between responders and nonresponders with a sensitivity of 90% (95% CI = 69%-99%) and a specificity of 87% (95% CI = 60%-98%). The area under the receiver operating characteristic (ROC) curve was 0.957 ± 0.035 for ΔPP(ART). Before VE, a ΔPP(CNAP) >11% discriminated between responders and nonresponders with a sensitivity of 85% (95% CI = 62%-97%) and a specificity of 100% (95% CI = 78%-100%). The area under the ROC curve was 0.942 ± 0.040 for ΔPP(CNAP). There was no significant difference between the area under the ROC curve for ΔPP(ART) and ΔPP(CNAP). CONCLUSIONS: A value of ΔPP(CNAP) >11% has a sensitivity of at least 62% in predicting preload-dependent responders to VE in mechanically ventilated patients during general anesthesia.