Multicenter parallel randomized trial evaluating incisional negative pressure wound therapy for the prevention of surgical site infection after lower extremity bypass.

OBJECTIVE: Incisional negative pressure wound therapy (iNPWT) applied over all incisions after lower extremity bypass in the prevention of surgical site infections (SSIs) is unclear. The primary and secondary aims of this study were to investigate if prophylactic iNPWT after the elective lower extremity bypass prevents SSI and other surgical wound complications. METHODS: This was a multicenter, parallel, randomized controlled trial. Patients undergoing elective lower extremity bypass in 3 hospitals were randomized to either iNPWT or standard dressings. SSIs or other wound complications were assessed within the first 90 days by wound care professionals blinded to the randomized result. The validated Additional treatment, Serous discharge, Erythema, Purulent exudate, Separation of deep tissues, Isolation of bacteria, and Stay (ASEPSIS) score was used to objectively assess the wounds. ASEPSIS score ≥21 is defined as an SSI. Unilateral and bilateral groups were analyzed with the Fisher exact test and the McNemar test, respectively. RESULTS: In the unilateral group (n = 100), the incidence of SSI in the iNPWT group was 34.9% (15/43), compared with 40.3% (23/57) in the control group, according to the ASEPSIS score (P = .678). In the bilateral group (n = 7), the SSI rate was 14.3% (1/7) in the iNPWT group compared with 14.3% (1/7) in the control group (P = 1.00). In the unilateral group, there was a higher wound dehiscence rate in the control group (43.9%) compared with the iNPWT group (23.3%) (P = .0366). No serious iNPWT-related adverse events were recorded. CONCLUSIONS: There was no reduction of SSI rates in leg incisions with iNPWT compared with standard dressings in patients undergoing elective lower extremity bypass, whereas iNPWT reduced the incidence of wound dehiscence.

Semi-Conservative Treatment Versus Radical Surgery in Abdominal Aortic Graft and Endograft Infections.

OBJECTIVE: Abdominal aortic graft and endograft infections (AGIs) are rare complications following aortic surgery. Radical surgery (RS) with resection of the infected graft and reconstruction with extra-anatomical bypass or in situ reconstruction is the preferred therapy. For patients unfit for RS, a semi-conservative (SC), graft preserving strategy is possible. This paper aimed to compare survival and infection outcomes between RS and SC treatment for AGI in a nationwide cohort. METHODS: Patients with abdominal AGI related surgery in Sweden between January 1995 and May 2017 were identified. The Management of Aortic Graft Infection Collaboration (MAGIC) criteria were used for the definition of AGI. Multivariable regression was performed to identify factors associated with mortality. RESULTS: One hundred and sixty-nine patients with surgically treated abdominal AGI were identified, comprising 43 SC (14 endografts; 53% with a graft enteric fistula [GEF] in total) and 126 RS (26 endografts; 50% with a GEF in total). The SC cohort was older and had a higher frequency of cardiac comorbidities. There was a non-significant trend towards lower Kaplan-Meier estimated five year survival for SC vs. RS (30.2% vs. 48.4%; p = .066). A non-significant trend was identified towards worse Kaplan-Meier estimated five year survival for SC patients with a GEF vs. without a GEF (21.7% vs. 40.1%; p = .097). There were significantly more recurrent graft infections comparing SC with RS (45.4% vs. 19.3%; p < .001). In a Cox regression model adjusting for confounders, there was no difference in five year survival comparing SC vs. RS (HR 1.0, 95% CI 0.6 - 1.5). CONCLUSION: In this national AGI cohort, there was no mortality difference comparing SC and RS for AGI when adjusting for comorbidities. Presence of GEF probably negatively impacts survival outcomes of SC patients. Rates of recurrent infection remain high for SC treated patients.

Editor's Choice - Outcome of Radical Surgical Treatment of Abdominal Aortic Graft and Endograft Infections Comparing Extra-anatomic Bypass with In Situ Reconstruction: A Nationwide Multicentre Study.

OBJECTIVE: Abdominal aortic graft and endograft infection (AGI) is primarily treated by resection of the infected graft and restoration of distal perfusion through extra-anatomic bypass (EAB) or in situ reconstruction/repair (ISR). The aim of this study was to compare these surgical strategies in a nationwide multicentre retrospective cohort study. METHODS: The Swedish Vascular Registry (Swedvasc) was used to identify surgically treated abdominal AGIs in Sweden between January 1995 and May 2017. The primary aim was to compare short and long term survival, as well as complications for EAB and ISR. RESULTS: Some 126 radically surgically treated AGI patients were identified - 102 graft infections and 24 endograft infections - treated by EAB: 71 and ISR: 55 (23 neo-aorto-iliac systems, NAISs). No differences in early 30 day (EAB 81.7% vs. ISR 76.4%, p = .46), or long term five year survival (48.2% vs. 49.9%, p = .87) were identified. There was no survival difference comparing NAIS to other ISR strategies. The frequency of recurrent graft infection during follow up was similar: EAB 20.3% vs. ISR 17.0% (p = .56). Survival and re-infection rates of the new conduit did not differ between NAIS and other ISR strategies. Age ≥ 75 years (odds ratio [OR] 4.0, confidence interval [CI] 1.1 - 14.8), coronary artery disease (OR 4.2, CI 1.2 - 15.1) and post-operative circulatory complications (OR 5.2, CI 1.2 - 22.5) were associated with early death. Prolonged antimicrobial therapy (> 3 months) was associated with reduced long term mortality (HR 0.3, CI 0.1 - 0.9). CONCLUSION: In this nationwide multicentre study comparing outcomes of radically treated AGI, no differences in survival or re-infection rate could be identified comparing EAB and ISR.

Healthcare professionals' experiences of being observed regarding hygiene routines: the Hawthorne effect in vascular surgery.

BACKGROUND: The Hawthorne Effect is the change in behaviour by subjects due to their awareness of being observed and is evident in both research and clinical settings as a result of various forms of observation. When the Hawthorne effect exists, it is short-lived, and likely leads to increased productivity, compliance, or adherence to standard protocols. This study is a qualitative component of an ongoing multicentre study, examining the role of Incisional Negative Pressure Wound Therapy after vascular surgery (INVIPS Trial). Here we examine the factors that influence hygiene and the role of the Hawthorne effect on the adherence of healthcare professionals to standard hygiene precautions. METHODS: This is a qualitative interview study, investigating how healthcare professionals perceive the observation regarding hygiene routines and their compliance with them. Seven semi-structured focus group interviews were conducted, each interview included a different staff category and one individual interview with a nurse from the Department for Communicable Disease Control. Additionally, a structured questionnaire interview was performed with environmental services staff. The results were analysed based on the inductive qualitative content analysis approach. RESULTS: The analysis revealed four themes and 12 subthemes. Communication and hindering hierarchy were found to be crucial. Healthcare professionals sought more personal and direct feedback. All participants believed that there were routines that should be adhered to but did not know where to find information on them. Staff in the operating theatre were most meticulous in adhering to standard hygiene precautions. The need to give observers a clear mandate and support their work was identified. The staff had different opinions concerning the patient's awareness of the importance of hygiene following surgery. The INVIPS Trial had mediated the Hawthorne effect. CONCLUSION: The results of this study indicate that the themes identified, encompassing communication, behaviour, rules and routines, and work environment, influence the adherence of healthcare professionals to standard precautions to a considerable extent of which many factors could be mediated by a Hawthorne effect. It is important that managers within the healthcare system put into place an improved and sustainable hygiene care to reduce the rate of surgical site infections after vascular surgery.

Incisional negative pressure wound therapy for the prevention of surgical site infection after open lower limb revascularization - Rationale and design of a multi-center randomized controlled trial.

INTRODUCTION: Lower limb revascularization with inguinal incisions is a common vascular surgical procedure. Due to risk of injury to lymphatic vessels and a diverse bacterial flora in the groin, surgical site infections (SSI) represent a common and sometimes life-threatening complication. While transverse incisions in endovascular aneurysm repair has a low SSI rate, vertical incisions in thrombendarterectomy (TEA) has a higher risk and bypass the highest risk. This randomized controlled trial (RCT) will investigate the protective role of negative pressure wound therapy (NPWT) on closed inguinal incisions in elective vascular surgery undergoing TEA and bypass procedures, respectively, to prevent SSI. METHODS: This RCT registered at ClinicalTrials.gov (Identifier: NCT01913132) compares the effects of a NPWT dressing (PICO™, Smith & Nephew, UK) to standard wound dressing on postoperative SSI. The multi-center study includes two distinct vascular procedures with different SSI risk profiles: TEA and lower limb bypass. Three hundred and fifty-eight groin incisions are anticipated to be included in the TEA group and 133 inguinal incisions in the bypass group. Bilateral inguinal incisions will be randomized to NPWT in one groin and control dressing in the contralateral groin, and this dependency was accounted for in sample size calculation and will be addressed in data analysis. DISCUSSION: This RCT attempts to evaluate the potential benefit of NPWT on closed inguinal incisions after two distinct vascular procedures at high risk of SSI. Outcome of this trial could have implications on postoperative wound care in both vascular and non-vascular surgical patients.

Antibiotic Prophylaxis With Trimethoprim/Sulfamethoxazole Instead of Cloxacillin/Cefotaxime Increases Inguinal Surgical Site Infection Rate After Lower Extremity Revascularization.

Due to the consistently high proportion of surgical site infections (SSI) after vascular surgery, a change of prophylactic antibiotic therapy from cloxacillin/cefotaxime to trimethoprim/sulfamethoxazole (TMP-SMX) was conducted in 2016. The study included consecutive patients undergoing lower extremity revascularization due to acute or chronic lower extremity arterial disease. The antibiotic regime was changed in between the two sampling periods (2014 -2016 versus 2016 -2017). The diagnosis of SSI was based on clinical examination and microbiological results, and severity was classified according to the Szilagyi classification. One hundred and twenty-two patients in the cloxacillin/cefotaxime and 67 patients in the TMP-SMX group were included. The SSI rates were 32.0% and 40.3%, respectively (p=0.25). The proportion of women were higher in the TMP-SMX group (32.8% versus 47.8%, respectively, p=0.043). No other differences between the two groups were found regarding patient, vascular surgery procedure characteristics or severity of SSI. Groin infection rate was higher in the TMP-SMX group (15.4% versus 30.5%, respectively, p=0.022). When adjusting for gender, groin infection was more common in the TMP-SMX group (Odds Ratio 2.5, 95% CI 1.1 -5.4). The groin SSI rate was higher after elective surgery in the TMP-SMX group (13.0% versus 27.8%, respectively, p=0.027), and also after adjusting for gender (Odds Ratio 2.6, 95% CI 1.1 -6.2). The change in antibiotic prophylaxis from Cloxacillin/Cefotaxime to TMP-SMX was associated with an increased rate of inguinal SSI in patients undergoing lower extremity revascularization, despite a possible Hawthorne effect.

Low wall stress in the popliteal artery: Other mechanisms responsible for the predilection of aneurysmal dilatation?

The popliteal artery (PA) is, after aorta, the most common site for aneurysm formation. Why the PA is more susceptible than other peripheral muscular arteries is unknown. We hypothesized that the wall composition, which in turn affects wall properties, as well as the circumferential wall stress (WS) imposed on the arterial wall, might differ compared to other muscular arteries. The aim was to study the WS of the PA in healthy subjects with the adjacent, muscular, common femoral artery (CFA) as a comparison. Ninety-four healthy subjects were included in this study (45 males, aged 10-78 years and 49 females, aged 10-83 years). The diameter and intima-media thickness (IMT) in the PA and CFA were investigated with ultrasound. Together with blood pressure the WS was defined according to the law of Laplace adjusted for IMT. The diameter increased with age in both PA and CFA (p<0.001), with males having a larger diameter than females (p<0.001). IMT increased with age in both PA and CFA (p<0.001), with higher IMT values in males only in PA (p<0.001). The calculated WS was unchanged with age in both arteries, but lower in PA than in CFA in both sexes (p<0.001). In conclusion, this study shows that the PA and CFA WS is maintained during aging, probably due to a compensatory remodelling response with an increase in arterial wall thickness. However, the stress imposed on the PA wall is quite low, indicating that mechanisms other than WS contribute to the process of pathological arterial dilatation in the PA.

Age-related increase in wall stress of the human abdominal aorta: an in vivo study.

BACKGROUND: The regulation of wall stress in the abdominal aorta (AA) of humans might be of specific interest, because the AA is the most common site for aneurysm formation in which wall stress seems to be an important pathophysiological factor. We studied the age-related changes in wall stress of the AA in healthy subjects, with the common carotid artery (CCA) as a comparison. METHODS: A total of 111 healthy subjects were examined with B-mode ultrasonography to determine the lumen diameter and intima-media thickness (IMT) in the AA and the CCA. RESULTS: Aortic IMT was affected by age in men and by both age and lumen diameter in women. Carotid IMT was affected by age and pulse pressure in both men and women. Wall stress was higher in the AA than in the CCA (P < .001), and men had higher wall stress than women in both the AA (P < .001) and the CCA (P < .05). Furthermore, wall stress was constant during life in the CCA of men and women and in the AA of women. In the male aorta, however, wall stress increased with age (P < 0.01). CONCLUSIONS: Arterial diameters increase with age, and a compensatory thickening of the arterial wall prevents the circumferential wall stress from increasing. However, this compensatory response is insufficient in the male AA and results in an increase in stress with age. These findings might explain the propensity for aneurysms to develop in the AA of men.

Noninvasive ultrasound measurements of aortic intima-media thickness: implications for in vivo study of aortic wall stress.

OBJECT: The abdominal aorta (AA) has a predilection for aneurysm formation. An etiologic factor may be underlying aortic wall stress. The purpose of this study was to examine whether the intima-media thickness (IMT) of the AA, as a surrogate to arterial wall thickness, can be measured noninvasively with satisfactory results to calculate circumferential wall stress, and to evaluate regional and gender differences in wall stress. METHODS: Sixty-five middle-aged healthy subjects were examined with B-mode ultrasound to determine the diameter and IMT in the infrarenal AA, common carotid artery (CCA), common femoral artery (CFA), and popliteal artery (PA). Blood pressure was measured noninvasively in the brachial artery. Wall stress was calculated according to the law of LaPlace. RESULTS: Intraobserver variability for the IMT in the AA showed a coefficient of variation of 11%. IMT was thickest in the AA compared with the CCA, CFA, and PA (P <.001). There was a gender difference in IMT in the CFA (P <.05) and PA (P <.01) but not in the AA. Greater wall stress was found in the AA than in the CCA (P <.001) and PA (P <.001), with men having greater wall stress in all studied arterial regions. CONCLUSIONS: Aortic IMT can be satisfactorily studied in vivo with noninvasive B-mode ultrasound. There are gender differences in IMT and wall stress, and the largest wall stress is found in the AA in men, which might be important in aneurysm development.