Risk factors associated with surgical site infections following vascular surgery at a German university hospital

Efficacy of Strategies Intended to Prevent Surgical Site Infection After Lower Limb Revascularization Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The objective of this study is to evaluate the efficacy of strategies intended to prevent surgical site infection (SSI) after lower limb revascularization surgery.

BACKGROUND

SSIs are common, costly complications of lower limb revascularization surgery associated with significant morbidity and mortality.

METHODS

We searched MEDLINE, EMBASE, CENTRAL, and Evidence-Based Medicine Reviews (inception to April 28, 2022). Two investigators independently screened abstracts and full-text articles, extracted data, and assessed the risk of bias. We included randomized controlled trials (RCTs) that evaluated strategies intended to prevent SSI after lower limb revascularization surgery for peripheral artery disease. We used random-effects models to pool data and GRADE to assess certainty.

RESULTS

Among 6258 identified citations, we included 26 RCTs (n=4752 patients) that evaluated 12 strategies to prevent SSI. Preincision antibiotics [risk ratio (RR)=0.25; 95% CI, 0.11-0.57; n=4 studies; I2 statistic=7.1%; high certainty] and incisional negative-pressure wound therapy (iNPWT) (RR=0.54; 95% CI, 0.38-0.78; n=5 studies; I2 statistic=7.2%; high certainty) reduced pooled risk of early (≤30 days) SSI. iNPWT also reduced the risk of longer-term (>30 days) SSI (pooled-RR=0.44; 95% CI, 0.26-0.73; n=2 studies; I2 =0%; low certainty). Strategies with uncertain effects on risk of SSI included preincision ultrasound vein mapping (RR=0.58; 95% CI, 0.33-1.01; n=1 study); transverse groin incisions (RR=0.33; 95% CI, 0.097-1.15; n=1 study), antibiotic-bonded prosthetic bypass grafts (RR=0.74; 95% CI, 0.44-1.25; n=1 study; n=257 patients), and postoperative oxygen administration (RR=0.66; 95% CI, 0.42-1.03; n=1 study) (low certainty for all).

CONCLUSIONS

Preincision antibiotics and iNPWT reduce the risk of early SSI after lower limb revascularization surgery. Confirmatory trials are required to determine whether other promising strategies also reduce SSI risk.

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.

Machine-Learning Models for Predicting Surgical Site Infections using Patient Pre-Operative Risk and Surgical Procedure Factors

BACKGROUND

Surgical site infections (SSIs) are a significant healthcare problem as they can cause increased medical costs and increased morbidity and mortality. Assessing a patient's pre-operative risk factors can improve risk stratification and help guide the surgical decision-making process. Previous efforts to use pre-operative risk factors to predict the occurrence of SSIs have relied upon traditional statistical modeling approaches. The aim of this paper is to develop and validate, using state-of-the-art machine learning (ML) approaches, classification models for the occurrence of SSI to improve upon previous models.

METHODS

In this work, using the American College of Surgeons' National Surgical Quality Improvement Program (ACS NSQIP) database, the performances (e.g., prediction accuracy) of seven different ML approaches (Logistic Regression (LR), Naïve Bayesian (NB), Random Forest (RF), Decision Tree (DT), Support Vector Machine (SVM), Artificial Neural Network (ANN), and Deep Neural Network (DNN)) were compared. The performance of these models was evaluated using the area under the curve, accuracy, precision, sensitivity, and F1-score metrics.

RESULTS

Overall, 2,882,526 surgical procedures were identified in the study for the SSI predictive models' development. The results indicate that the DNN model offers the best predictive performance with 10-fold compared to the other six approaches considered (area under the curve = 0.8518, accuracy = 0.8518, precision = 0.8517, sensitivity = 0.8527, F1-score = 0.8518). Emergency case surgeries, American Society of Anesthesiologists (ASA) Index of 4 (ASA_4), BMI, Vascular surgeries, and general surgeries were most significant influencing features towards developing an SSI.

CONCLUSION

Equally important is that the commonly used LR approach for SSI prediction displayed mediocre performance. The results are encouraging as they suggest that the prediction performance for SSIs can be improved using modern ML approaches.

Groin wound infection after vascular exposure (GIVE) multicentre cohort study

Surgical site infections (SSIs) of groin wounds are a common and potentially preventable cause of morbidity, mortality, and healthcare costs in vascular surgery. Our aim was to define the contemporaneous rate of groin SSIs, determine clinical sequelae, and identify risk factors for SSI. An international multicentre prospective observational cohort study of consecutive patients undergoing groin incision for femoral vessel access in vascular surgery was undertaken over 3 months, follow-up was 90 days. The primary outcome was the incidence of groin wound SSI. 1337 groin incisions (1039 patients) from 37 centres were included. 115 groin incisions (8.6%) developed SSI, of which 62 (4.6%) were superficial. Patients who developed an SSI had a significantly longer length of hospital stay (6 versus 5 days, P = .005), a significantly higher rate of post-operative acute kidney injury (19.6% versus 11.7%, P = .018), with no significant difference in 90-day mortality. Female sex, Body mass index≥30 kg/m2 , ischaemic heart disease, aqueous betadine skin preparation, bypass/patch use (vein, xenograft, or prosthetic), and increased operative time were independent predictors of SSI. Groin infections, which are clinically apparent to the treating vascular unit, are frequent and their development carries significant clinical sequelae. Risk factors include modifiable and non-modifiable variables.

Vein Harvest Wound Healing after Bypass Surgery for Critical Limb Ischemia

BACKGROUND

Lower-limb revascularization surgery, especially when performed using the great saphenous vein, predisposes patients to major surgical trauma on initially ischemic tissue. Vein harvest wounds (VHWs) after infrainguinal revascularization heal slowly. This study's aim was to assess the factors associated with VHW healing after infrainquinal bypass surgery for critical limb ischemia (CLI).

METHODS

A retrospective patient record study was conducted. All patients with CLI who underwent infrainguinal bypass surgery with autologous vein graft between January 1, 2015, and December 31, 2017, in the Turku University Hospital, were included. Follow-up data were collected until February 28, 2018. The following data was collected from the patient files; risk factors, ankle-brachial indices (ABIs), systolic toe pressures (STPs), the presence of an ischemic ulcer, VHW dehiscence, and the time when the VHW was completely healed. Procedures with outflow vessels at either popliteal or tibial artery were analyzed separately. Descriptive and univariate statistical analyses were performed.

RESULTS

Altogether, 195 patients were operated on for CLI, of whom 133 (68.2%) patients had ischemic ulcers. The mean follow-up time was 535.0 days (range 3.0-1143.0 days). The mean ABI improvement was 0.49 (P = 0.00), and STP improvement, 39.9 mm Hg (P = 0.00). The median time taken when VHW was healed was 48.0 days (95% confidence interval [CI], 39.4-56.6) in patients without ischemic ulcers and 82.0 days (95% CI, 59.7-104.3) in patients with ischemic ulcers, P = 0.03. VHW in patients who underwent popliteal artery bypass (62 days, 95% CI, 12.9-93.0) healed faster than VHW in those who underwent tibial artery bypass (132 days, 95% CI, 48.0-93.0), P = 0.02. Risk factors and the preoperative or postoperative ABIs or STPs had no effect on VHW healing time.

CONCLUSIONS

VHW healing was remarkably slower after revascularization surgery in patients with an ischemic foot ulcer than in those without ischemic ulcers.

Timing of surgical site infection and pulmonary complications after laparotomy

BACKGROUND

Surgical site infection (SSI) and other postoperative complications are associated with high costs, morbidity, secondary surgery, and mortality. Many studies have identified factors that may prevent SSI and pulmonary complications, but it is important to know when they in fact occur. The aim of this study was to investigate the diagnostic timing of surgical site infections and pulmonary complications after laparotomy.

MATERIAL AND METHODS

This is a secondary analysis of the PROXI trial which was a randomized clinical trial conducted in 1400 patients undergoing elective or emergent laparotomy. Patients were randomly allocated to either 80% or 30% perioperative inspiratory oxygen fraction.

RESULTS

SSI or pulmonary complications were diagnosed in 24.2% (95% CI: 22.0%-26.5%) of the patients at a median of 9 days [IQR: 5-15] after surgery. Most common was surgical site infection (19.6%); median time 10 days after surgery [IQR: 7-18]. The corresponding figures for anastomotic leakage was 5.7%, 8 days [IQR: 6-10]; pneumonia 3.5%, 5 days [IQR: 3-9]; and respiratory failure 2.3%, 3 days [IQR: 1-8]. The oxygen allocation was not significantly related to time of diagnosis for postoperative surgical site infections or pulmonary complications.

CONCLUSION

A high percentage of patients undergoing laparotomy develop a postoperative complication. This study adds new knowledge by identifying time intervals within which medical professionals should be aware of surgical site infections and pulmonary complications in order to initiate appropriate treatment of the patients.

Axillobifemoral Bypasses: Reappraisal of an Extra-Anatomic Bypass by Analysis of Results and Prognostic Factors

BACKGROUND

Axillobifemoral bypass (AFB) is method of second choice. It is reserved for patients at high operative risk or to bypass infected vessels or grafts. In this study, we analyzed prognostic factors for AFB patency and limb salvage rate to facilitate the choice of procedure.

METHODS

Between Jan 2006 and Aug 2013, 45 patients underwent AFB surgery in our department, 24 for critical limb ischemia (CLI) and 23 for infection. Endpoints of study were graft occlusion, graft infection, amputation and patient's death. Prognostic factors were compared by univariate analysis for each indication group. Mean follow-up was 40.2 (±23.2) months.

RESULTS

Complication rate was significantly higher in infection group (88.0 vs. 54.4%, p = 0.003) and in emergency surgery (83.3 vs. 56.9%, p = 0.023). Overall primary patency rate after AFB procedures was 66.7% after 1, 3, and 5 years, while secondary patency rate was 91.1% after 1 year, 82.2% after 3 years and 80.0% after 5 years. The primary and secondary patency rates did not significantly differ between the both groups (p = 0.059 and p = 0.136). Following prognostic factors showed a statistically significant influence on patency rates in CLI group: >1 previous vascular surgical intervention, patch angioplasty at the distal anastomosis site, complications after previous vascular surgery, and perioperative intake of platelet aggregation inhibitor. Only the employed bypass material had a statistical significant influence on the secondary patency rates in the infection group. Overall limb salvage rate was 82.2% after 1 year, 80.0% after 3 years and 77.8% after 5 years. There were statistically significant differences in the limb salvage rates depending on emergency surgery and a 3-vessel-run-off in the lower leg in both indication groups.

CONCLUSION

AFB have acceptable patency and limb salvage rates. AFB is a good alternative in patients with CLI at high operative risk or with infections of aortoiliac segments, even with endovascular approaches. They remain essential tools in vascular surgeon's repertoire.

Risk factors for surgical site infection following nonshunt pediatric neurosurgery: a review of 9296 procedures from a national database and comparison with a single-center experience

OBJECTIVE Surgical site infection (SSI) following CSF shunt operations has been well studied, yet risk factors for nonshunt pediatric neurosurgery are less well understood. The purpose of this study was to determine SSI rates and risk factors following nonshunt pediatric neurosurgery using a nationwide patient cohort and an institutional data set specifically for better understanding SSI. METHODS The authors reviewed the American College of Surgeons National Surgical Quality Improvement Program-Pediatric (ACS NSQIP-P) database for the years 2012-2014, including all neurosurgical procedures performed on pediatric patients except CSF shunts and hematoma evacuations. SSI included deep (intracranial abscesses, meningitis, osteomyelitis, and ventriculitis) and superficial wound infections. The authors performed univariate analyses of SSI association with procedure, demographic, comorbidity, operative, and hospital variables, with subsequent multivariate logistic regression analysis to determine independent risk factors for SSI within 30 days of the index procedure. A similar analysis was performed using a detailed institutional infection database from Children's of Alabama (COA). RESULTS A total of 9296 nonshunt procedures were identified in NSQIP-P with an overall 30-day SSI rate of 2.7%. The 30-day SSI rate in the COA institutional database was similar (3.3% of 1103 procedures, p = 0.325). Postoperative time to SSI in NSQIP-P and COA was 14.6 ± 6.8 days and 14.8 ± 7.3 days, respectively (mean ± SD). Myelomeningocele (4.3% in NSQIP-P, 6.3% in COA), spine (3.5%, 4.9%), and epilepsy (3.4%, 3.1%) procedure categories had the highest SSI rates by procedure category in both NSQIP-P and COA. Independent SSI risk factors in NSQIP-P included postoperative pneumonia (OR 4.761, 95% CI 1.269-17.857, p = 0.021), immune disease/immunosuppressant use (OR 3.671, 95% CI 1.371-9.827, p = 0.010), cerebral palsy (OR 2.835, 95% CI 1.463-5.494, p = 0.002), emergency operation (OR 1.843, 95% CI 1.011-3.360, p = 0.046), spine procedures (OR 1.673, 95% CI 1.036-2.702, p = 0.035), acquired CNS abnormality (OR 1.620, 95% CI 1.085-2.420, p = 0.018), and female sex (OR 1.475, 95% CI 1.062-2.049, p = 0.021). The only COA factor independently associated with SSI in the COA database included clean-contaminated wound classification (OR 3.887, 95% CI 1.354-11.153, p = 0.012), with public insurance (OR 1.966, 95% CI 0.957-4.041, p = 0.066) and spine procedures (OR 1.982, 95% CI 0.955-4.114, p = 0.066) approaching significance. Both NSQIP-P and COA multivariate model C-statistics were > 0.7. CONCLUSIONS The NSQIP-P SSI rates, but not risk factors, were similar to data from a single center.

Diagnosis and Treatment of Vascular Surgery Related Infection

Surgical site infection (SSI) is an important component of infections acquired from hospital. The most significant feature of vascular surgery different from other surgeries is frequent application of artificial grafts. Once SSI occurs after vascular operations with grafts, it might results in a serious disaster. Staphylococcus aureus and coagulase-negative Staphylococcus are the most common pathogenic bacteria for SSI after vascular surgery. Although SSI in vascular surgery often lacks of typical clinical characters, some clinical symptoms, laboratory data and certain imaging procedures may help to diagnose. In most cases of SSI after vascular procedures, the artificial grafts must be removed and sensitive antibiotics should be administered. However, for different cases, personalized management plan should be made depending on the severity and location of SSI.

Fatal persistent methicillin-resistant Staphylococcus aureus bacteremia and vascular graft infections complicated with the formation of multiple abscesses despite aggressive medical therapy

A 40-year-old man underwent ascending aorta replacement for an acute type A aortic dissection. After the operations, methicillin-resistant Staphylococcus aureus was identified in sputum and blood cultures. Although anti-methicillin-resistant Staphylococcus aureus drugs were administered, most of the intermittent blood cultures remained positive. The focus of methicillin-resistant Staphylococcus aureus infection was not evident in the early stages, and no specific symptoms such as abscess or endocarditis were observed. However, abscesses in the brain, mediastinum and spleen were found 3 years after the operation. The minimum inhibitory concentration of vancomycin gradually increased from 1 to 4 µg/mL during the course of treatment. This case provides evidence for a potential role of combination therapy.

Surgical wound infections after peripheral vascular surgery

Surgical wound infection is one of the most common complications after peripheral vascular surgery. It increases the affected patient's risk for major amputation as well as mortality. Furthermore, surgical wound infection is an additional cost. Wound infections after vascular surgery are of multifactorial nature and generally result from the interplay of patient- and procedure-related factors. The use of systemic antibiotic prophylaxis may be the most important method in preventing surgical wound infections. In this review article, we report the current literature of surgical wound infections after peripheral vascular surgery.

The association of perioperative dexamethasone, smoking and alcohol abuse with wound complications after laparotomy

BACKGROUND

A number of perioperative risk factors may suppress the immune system and contribute to the development of post-operative complications. The association between surgical site infection (SSI) and other wound-related complications resulting from immunosuppression through either perioperative administration of dexamethasone, pre-operative smoking or alcohol abuse is, however, uncertain.

METHODS

This study was a post hoc analysis of data from the PROXI randomized trial in 1386 patients who underwent emergency or elective laparotomy. We assessed the associations of use of dexamethasone, smoking status and alcohol abuse with the primary outcome, being a composite of SSI, anastomotic leak, wound dehiscence, burst abdomen and 30-day mortality.

RESULTS

The primary outcome occurred in 21% of patients receiving dexamethasone versus 28% of patients not receiving dexamethasone, and this was not statistically significant when adjusting for stratification variables originally used in the PROXI trial [OR 0.90, 95% CI (0.65-1.24)]. In smokers, the primary outcome occurred in 32%, compared with 23% of non-smokers (P = 0.0001). Smokers also had a higher frequency of SSI (25% vs 17%, P < 0.0001) and burst abdomen (3.8% vs 2.4%, P = 0.04). In alcohol abusers, the primary outcome occurred in 48%, compared with 25% in patients who did not abuse alcohol (P = 0.0006). Burst abdomen occurred more commonly in alcohol abusers (15% vs 2.3%, P < 0.0001).

CONCLUSION

Perioperative administration of dexamethasone was not significantly associated with SSI or other wound-related complications. Conversely, smoking and alcohol abuse were both significant predictors of the primary outcome consisting of wound-related complications and mortality.