The Influence of Preoperative Anemia on Clinical Outcomes After Infrainguinal Bypass Surgery

Risk Factors for Surgical Site Infection after Lower Limb Revascularisation Surgery: a Systematic Review and Meta-Analysis of Prognostic Studies

OBJECTIVE

To systematically review and meta-analyse adjusted risk factors for surgical site infection (SSI) after lower limb revascularisation surgery.

DATA SOURCES

MEDLINE, Embase, Evidence Based Medicine Reviews, and the Cochrane Central Register of Controlled Trials (inception to 28 April 2022).

REVIEW METHODS

Systematic review and meta-analysis conducted according to PRISMA guidelines. After protocol registration, databases were searched. Studies reporting adjusted risk factors for SSI in adults who underwent lower limb revascularisation surgery for peripheral artery disease were included. Adjusted odds ratios (ORs) were pooled using random effects models. GRADE was used to assess certainty.

RESULTS

Among 6 377 citations identified, 50 studies (n = 271 125 patients) were included. The cumulative incidence of SSI was 12 (95% confidence interval [CI] 10 - 13) per 100 patients. Studies reported 139 potential SSI risk factors adjusted for a median of 12 (range 1 - 69) potential confounding factors. Risk factors that increased the pooled adjusted odds of SSI included: female sex (pooled OR 1.41, 95% CI 1.20 - 1.64; high certainty); dependent functional status (pooled OR 1.18, 95% CI 1.03 - 1.35; low certainty); being overweight (pooled OR 1.82, 95% CI 1.29 - 2.56; moderate certainty), obese (pooled OR 2.20, 95% CI 1.44 - 3.36; high certainty), or morbidly obese (pooled OR 1.65, 95% CI 1.08 - 2.52; moderate certainty); chronic obstructive pulmonary disease (pooled OR 1.42, 95% CI 1.17 - 1.71; high certainty); chronic limb threatening ischaemia (pooled OR 1.67, 95% CI 1.22 - 2.29; moderate certainty); chronic kidney disease (pooled OR 2.13, 95% CI 1.18 - 3.83; moderate certainty); intra-operative (pooled OR 1.23, 95% CI 1.02 - 1.49), peri-operative (pooled OR 1.92, 95% CI 1.27 - 2.90), or post-operative (pooled OR 2.21, 95% CI 1.44 - 3.39) blood transfusion (moderate certainty for all); urgent or emergency surgery (pooled OR 2.12, 95% CI 1.22 - 3.70; moderate certainty); vein bypass and or patch instead of endarterectomy alone (pooled OR 1.86, 95% CI 1.33 - 2.59; moderate certainty); an operation lasting ≥ 3 hours (pooled OR 1.86, 95% CI 1.33 - 2.59; moderate certainty) or ≥ 5 hours (pooled OR 1.60, 95% CI 1.18 - 2.17; moderate certainty); and early or unplanned re-operation (pooled OR 4.50, 95% CI 2.18 - 9.32; low certainty).

CONCLUSION

This systematic review identified evidence informed SSI risk factors following lower limb revascularisation surgery. These may be used to develop improved SSI risk prediction tools and to identify patients who may benefit from evidence informed SSI prevention strategies.

The Impact of Pre-Operative Anaemia on One Year Amputation Free Survival and Re-Admissions in Patients Undergoing Vascular Surgery for Peripheral Arterial Disease: a National Vascular Registry Study

OBJECTIVE

Anaemia is common among patients undergoing surgery, but its association with post-operative outcomes in patients with peripheral arterial disease (PAD) is unclear. The aim of this observational population based study was to examine the association between pre-operative anaemia and one year outcomes after surgical revascularisation for PAD.

METHODS

This study used data from the National Vascular Registry, linked with an administrative database (Hospital Episode Statistics), to identify patients who underwent open surgical lower limb revascularisation for PAD in English NHS hospitals between January 2016 and December 2019. The primary outcome was one year amputation free survival. Secondary outcomes were one year re-admission rate, 30 day re-intervention rate, 30 day ipsilateral major amputation rate and 30 day death. Flexible parametric survival analysis and generalised linear regression were performed to assess the effect of anaemia on one year outcomes.

RESULTS

The analysis included 13 641 patients, 57.9% of whom had no anaemia, 23.8% mild, and 18.3% moderate or severe anaemia. At one year follow up, 80.6% of patients were alive and amputation free. The risk of one year amputation or death was elevated in patients with mild anaemia (adjusted HR 1.3; 95% CI 1.15 - 1.41) and moderate or severe anaemia (aHR 1.5; 1.33 - 1.67). Patients with moderate or severe anaemia experienced more re-admissions over one year (adjusted IRR 1.31; 1.26 - 1.37) and had higher odds of 30 day re-interventions (aOR 1.22; 1.04 - 1.45), 30 day ipsilateral major amputation (aOR 1.53; 1.17 - 2.01), and 30 day death (aOR 1.39; 1.03 - 1.88) compared with patients with no anaemia.

CONCLUSION

Pre-operative anaemia is associated with lower one year amputation free survival and higher one year re-admission rates following surgical revascularisation in patients with PAD. Research is required to evaluate whether interventions to correct anaemia improve outcomes after lower limb revascularisation.

A framework for perioperative care for lower extremity vascular bypasses: A Consensus Statement by the Enhanced Recovery after Surgery (ERAS®) Society and Society for Vascular Surgery

The Society for Vascular Surgery and the Enhanced Recovery After Surgery (ERAS) Society formally collaborated and elected an international, multi-disciplinary panel of experts to review the literature and provide evidence-based suggestions for coordinated perioperative care for patients undergoing infrainguinal bypass surgery for peripheral artery disease. Structured around the ERAS core elements, 26 suggestions were made and organized into preadmission, preoperative, intraoperative, and postoperative sections.

The adverse impact of pre-operative anaemia on survival following major lower limb amputation

INTRODUCTION

Approximately 5000 major lower-limb amputations (MLLA) for PAD occur per-annum in the UK with clinical outcomes being poor for this high-risk cohort of patients. Existing evidence suggests that anaemic surgical patients have an increased 30-day mortality, but this has not been explored in the context of MLLA. Recent prioritization processes suggested that MLLAs are a target area for research into outcome improvement. This cohort study evaluates the impact of anaemia on the outcome of MLLA to understand if optimization might improve outcomes.

METHODS

All PAD patients undergoing MLLA during 2015-2018 at a tertiary vascular centre were reviewed. Patients were stratified into groups; non-anaemia (>12 g/dL), mild-anaemia (12-10 g/dL) and severe-anaemia (<10 g/dL) by pre-operative haemoglobin (Hb). Primary outcome was overall survival by Kaplan-Meier. Secondary outcomes included length of stay (LOS), post-operative blood-transfusion, surgical-site infection (SSI) and myocardial infarction (MI). Cox-proportional-hazard and receiver-operator characteristics (ROC) analyses were conducted.

RESULTS

345 patients were followed up over (mean) 23 months. 105 were non-anaemic, 111 mildly anaemic and 129 severely anaemic. Patients with severe-anaemia had a higher incidence of heart and renal failure (p = 0.003) than those with non- or mild-anaemia. Overall survival worsened significantly with increasing anaemia (p = 0.001). LOS was significantly longer in mild-anaemia which is 26 (16-43) days, (p = 0.006) and severe-anaemia of 28 days (17-40), (p < 0.001) compared to non-anaemia of 18 (10-30) days. Post-operative blood-transfusion (RBC) was required more frequently in 70.5% of severely anaemic patients (p < 0.001), compared to mildly anaemic (24.3%) and non-anaemic (7.6%) patients, with those receiving RBCs having a significantly worse survival. There was no difference in MI, SSI or wound dehiscence. Anaemia was significantly associated with mortality; (HR 1.7 (1.04-2.78), p = 0.03). A minimum-Hb of 10.4 g/L (by ROC) was identified as a cutoff Hb for an increased risk of mortality.

CONCLUSION

Pre-operative anaemia is associated with worse outcome following MLLA, with increasing severity of anaemia associated with increasing mortality and RBC transfusion being potentially detrimental. More work is required to prospectively evaluate this relationship in this complex and multi-morbid cohort of patients.

Risk Factors for Surgical Site Infections After Lower Extremity Open Revascularization

BACKGROUND

Surgical site infection (SSI) is a serious complication of lower extremity open revascularization and is associated with increased morbidity, increased healthcare costs, and decreased postoperative quality of life. The objective of this study was to determine factors associated with an increased risk of developing postoperative SSI in patients undergoing lower extremity revascularization. Associations between SSI and postoperative complications were also identified.

METHODS

Patients who underwent lower extremity open revascularization from 2014-2017 were identified using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). A multivariate logistic regression analysis was used to determine risk factors associated with SSIs within 30 days of the operation and postoperative complications. Odds ratios (ORs) were adjusted for demographics, preoperative comorbidities, procedure type, and intraoperative variables.

RESULTS

Ten thousand nine hundred ten patients who underwent lower extremity open revascularization were identified, with a mean age of 67.24 years and of whom 7,318 (67%) were male. Of the 10,910 patients, 922 (8.45%) had an SSI within 30 days of the operation. Risk factors associated with developing SSI included body mass index 25-29.9 (OR, 1.34; 95% confidence interval [CI], 1.08-1.67), body mass index ≥ 30 (OR, 2.12; 95% CI, 1.71-2.62), history of severe chronic obstructive pulmonary disease (OR, 1.47; 95% CI, 1.18-1.84), preprocedural beta-blocker use (OR, 1.25; CI 95%, 1.05-1.49), procedure time > 214 minutes (OR, 1.44; 95% CI, 1.22-1.70), and creatinine > 1.2 (OR 1.03; 95% CI, 0.87-1.21). One factor associated with a decreased risk of developing SSI was male gender (OR, 0.71; 95% CI, 0.60-0.84). Patients who developed an SSI were more likely to have adverse outcomes such as myocardial infarction/stroke, major amputation, bleeding requiring transfusion or secondary procedure, or require a reintervention in the treated segment.

CONCLUSIONS

There are various patient-related and operative factors that increase the likelihood of developing an SSI after lower extremity open revascularization. These findings indicate that addressing modifiable perioperative SSI risk factors may be beneficial in decreasing rates of SSI and improving postoperative outcomes.

Impact of Perioperative Blood Transfusion in Anemic Patients Undergoing Infra Inguinal Bypass

OBJECTIVE

Patients who present with lower extremity ischemia are frequently anemic and the optimal transfusion threshold for this cohort remains controversial. We sought to evaluate the impact of blood transfusion on postoperative major adverse cardiac events (MACE), including myocardial infarction, dysrhythmia, stroke, congestive heart failure, and 30-day mortality for these patients.

METHODS

All consecutive patients who underwent infra-inguinal bypass at our institution from 2011 to 2020 were included. Perioperative red blood cell transfusion was the primary exposure, and the primary outcome was MACE. Univariate and multivariable analyses were performed to assess the impact of patient and procedural variables, including red blood cell transfusion, stratified by hemoglobin (Hgb) nadir: <7, 7-8, and >8 g/dL.

RESULTS

Of the 287 patients reviewed for analysis, 146 (50.9%) had a perioperative transfusion (mean: 1.6 ± 3 units). Patients who received a transfusion had a mean nadir Hgb of 8.3 ± 1.0 g/dL, compared to 10.1 ± 1.7 g/dL without a transfusion. The overall incidence of MACE was 15.7% (45 of 287 patients). Univariate analysis demonstrated that MACE was associated with blood transfusion (P = 0.009), lower Hgb nadir (P = 0.02), and higher blood loss (P = 0.003). On multivariate analysis, transfusion was independently associated with MACE for patients with a Hgb nadir >8 g/dL (OR: 3.09; P = 0.006), but not for patients with Hgb nadir 7-8 g/dL (OR: 0.818; P = 0.77). Additionally, patients with MACE had significantly longer length of hospital stay than for patients without (13 vs. 7.7 days, P = 0.001).

CONCLUSIONS

For patients undergoing infra-inguinal bypass, receiving a red blood cell transfusion with a Hgb nadir >8 g/dL was associated with a 3-fold increase in MACE, with nearly twice the length of stay. For patients with a Hgb 7-8 g/dL, transfusion did not increase or reduce the incidence of MACE. These findings suggest no benefit of blood transfusion for patients with Hgb nadir >7 g/dL and harm for Hgb >8 g/dL, however causation cannot be proven due to the retrospective nature of the study and randomized studies are needed to confirm or refute these findings.

The Impact of Anemia on One-Year Amputation-Free Survival in Patients Undergoing Revascularization for Chronic Limb-Threatening Ischemia: A Retrospective Cohort Study

BACKGROUND

Anemia is potentially associated with increased morbidity and mortality following vascular surgery procedures. This study investigated whether peri-procedural anemia is associated with reduced 1-year amputation-free survival (AFS) in patients undergoing revascularization for chronic limb-threatening ischemia (CLTI).

METHODOLOGY

A retrospective analysis of patients diagnosed with CLTI between February 2018-February 2019, who subsequently underwent revascularization, was conducted. Hemoglobin concentration measured at index assessment was recorded and stratified by WHO criteria. Subsequent peri-procedural red blood cell transfusions (RBC) were also recorded. The primary outcome was 1-year AFS. Kaplan Meier survival analysis and Cox's proportional hazard modelling were conducted to assess the effect of anemia and peri-procedure transfusion on outcomes.

RESULTS

283 patients were analyzed, of which 148 (52.3%) were anemic. 53 patients (18.7%) underwent RBC transfusion. Patients with anemia had a significantly lower 1-year AFS (64.2% vs. 78.5%, P = 0.009). A significant difference in 1-year AFS was also observed based upon anemia severity (P = 0.008) and for patients who received RBC transfusion (45.3% vs 77.0%, P < 0.001). On multivariable analysis, moderately severe anemia was independently associated with increased risk of major amputation/death (aHR 1.90, 95% CI 1.06-3.38, P = 0.030). After adjusting for severity of baseline anemia, peri-procedural RBC transfusion was associated with a significant increase in the combined risk of major amputation/death (aHR 3.15, 95% CI 1.91-5.20, P < 0.001).

CONCLUSION

Moderately severe peri-procedural anemia and subsequent RBC transfusion are independently associated with reduced 1-year AFS in patients undergoing revascularization for CLTI. Future work should focus on investigating alternative measures to managing anemia in this cohort.

Anaemia: A risk factor for death and adverse outcomes following surgery for acute lower limb ischaemia

INTRODUCTION

Acute limb ischaemia (ALI) forms a significant part of the vascular surgery workload and carries with it high rates of morbidity and mortality. Anaemia is also common amongst vascular surgical patients and has been linked with poor outcomes in some subgroups. We aimed to assess the frequency of anaemia in patients with ALI and its impact on survival and complications following revascularisation to help direct future efforts to optimise outcomes in this patient group.

METHODS

A retrospective analysis of prospectively collected departmental data on patients undergoing surgical intervention for ALI between 2014 and 2018 was performed. Anaemia was defined as a pre-operative haemoglobin (Hb) of <120 g/L for women and <130 g/L for men. The primary outcome was overall survival, assessed with the Kaplan-Meier estimator, with application of Cox proportional hazard modelling to adjust for confounding covariates.

RESULTS

There were 158 patients who underwent treatment for ALI: 89 (56.3%) of these were non-anaemic with a mean Hb of 146 (SD = 18.4), and 69 (43.7%) were anaemic with a mean Hb of 106 (SD = 13.4). Anaemic patients had a significantly higher risk of death than their non-anaemic counterparts on univariate analysis (HR = 2.11, 95% CIs, 1.28-3.5, p = 0.0036). There was ongoing divergence in survival up to around 6 months between anaemic and non-anaemic groups. Under the Cox model, anaemia was similarly significant as a predictor of death (HR = 2.15, 95% CIs, 1.17-3.95, p = 0.013), accounting for recorded comorbidities, medication use and blood transfusion.

CONCLUSIONS

Anaemia is a significant and independent risk factor for death following revascularisation for ALI and can be potentially be modified. Vascular surgical centres should ensure they have robust pathways in place to identify and consider treating anaemia. There is scope for further work to assess how to best optimise a patient's levels of circulating haemoglobin.

Sarcopenia in Patients Undergoing Lower Limb Bypass Surgery is Associated with Higher Mortality and Major Amputation Rates

BACKGROUND

Sarcopenia is adversely associated with survival in several diseases. Vasculopathy is often associated with multimorbidity and consequent deconditioning with poor long-term outcomes. This study examined the impact of sarcopenia on clinical outcome in patients with and without critical limb-threatening ischaemia who underwent infrainguinal bypass surgery.

METHODS

All patients undergoing infra-inguinal surgical revascularisation in 2016-2018 were retrospectively reviewed. Sarcopenia was defined as a skeletal muscle area at the L3 vertebral level (defined as L3 muscle area < 114cm² for men or <89.8cm² for women) on CT angiography. The primary outcome was overall survival by analysed by time to event analysis. Secondary outcomes included ipsilateral major lower-limb amputation, length of hospital stay, myocardial infarction and surgical-site infection.

RESULTS

A total of 116 patients with a mean age of 66.9 years were included, with a mean follow-up of 21 months. 14 (12%) of patients were sarcopenic; there were more patients with diabetes (40% vs 7%) in the sarcopenic group, p=0.018. Age, gender, Rutherford grade at presentation, other co-morbidities, other laboratory tests, conduit material and Rutherford grade at presentation were similar in those with and without sarcopenia and were statistically insignificant upon testing. Overall survival was worse for sarcopenic patients (Log Rank P=0.001) and Hazard Ratio for death 5.8; 95%CI 1.8-19.1; P=0.001. Major lower-limb amputation occurred more frequently in patients with sarcopenia (7/14 [50%] vs 23/102 [23%]; P=0.046). There was no difference in other secondary outcomes including rates of graft occlusion, myocardial infarction, surgical site infection and length of stay. Adding SMA measurement to a multivariate generalised linear model including age, sex, diabetes, and haemoglobin improved the AUROC from 0.75-0.85.

CONCLUSION

In this cohort of patients undergoing vascular surgery, sarcopenia defined using L3 muscle area was significantly associated with overall mortality and major lower-limb amputation.

Etiology and Comorbidity Diagnoses Effect on Outcomes for Patients Undergoing Endoscopic Retrograde Cholangiopancreatography

Introduction

Endoscopic retrograde cholangiopancreatography (ERCP) is now the first-line approach to treating choledocholithiasis. As a minimally invasive procedure, it is considered relatively safe but still entails a higher risk than other routine endoscopic procedures. This study aims to look at possible patient etiologies and comorbidities that may affect patient outcomes. 

Methods

This study used the Nationwide Inpatient Sample (NIS) from the years 2012 - 2015 to collect anonymous patient data through the use of International Classification of Diseases, Ninth Revision (ICD-9) codes. Specific codes were used to determine the top five etiologies (or presenting diagnosis) for patients who had this surgery and to separate outpatients with specific comorbidity diagnoses. The IBM Statistical Package for Social Sciences (SPSS) (IBM SPSS Statistics, Armonk, NY) was then used to compare patients with these diagnoses or etiologies to those without to measure differences in patient outcomes, such as mortality, length of stay, and total charges.

Results

Patients who had an etiological diagnosis of acute kidney failure had worse outcomes than patients who were admitted for ERCP without that etiological diagnosis. There were also specific comorbidity diagnoses that were noted to have worse patient outcomes, including congestive heart failure, diabetes mellitus with complications, a coagulopathy disorder, anemia, or chronic liver disease. Additionally, patients who had both acute kidney disease and chronic liver disease had the worst outcomes.

Conclusions

This study highlights the need to understand all patient risk factors before having them undergo ERCP, especially in the setting of scheduled surgery. Working to control these factors before surgery can increase the possibility of avoiding negative outcomes like mortality, increased patient costs, and increased length of stay.