Surgical site infection: incidence and impact on hospital utilization and treatment costs

Negative pressure wound therapy compared with conventional wound dressings for closed incisions in orthopaedic trauma surgery: A meta-analysis

We performed a meta‐analysis to evaluate the effect of negative pressure wound therapy compared with conventional wound dressings on closed incisions in orthopaedic trauma surgery. A systematic literature search up to October 2021 was done and 12 studies included 3555 subjects with closed incisions in orthopaedic trauma surgery at the start of the study: 1833 of them were provided with negative pressure wound therapy and 1722 were conventional wound dressings. They were reporting relationships about the effect of negative pressure wound therapy compared with conventional wound dressings on closed incisions in orthopaedic trauma surgery. We calculated the odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) to assess the effect of negative pressure wound therapy compared with conventional wound dressings on closed incisions in orthopaedic trauma surgery using the dichotomous and continuous methods with a random or fixed‐effect model. Negative pressure wound therapy had significantly lower deep surgical site infection (OR, 0.65; 95% CI, 0.48–0.88, P = .005), superficial surgical site infection (OR, 0.23; 95% CI, 0.11–0.49, P = .31), and wound dehiscence (OR, 0.41; 95% CI, 0.21–0.80, P = .009) compared with conventional wound dressings in subjects with closed incisions in orthopaedic trauma surgery. However, negative pressure wound therapy had no significant effect on the length of hospital stay (MD, 0.29; 95% CI, −2.00‐ 2.58, P = .80) compared with conventional wound dressings in subjects with closed incisions in orthopaedic trauma surgery. Negative pressure wound therapy had significantly lower deep surgical site infection, superficial surgical site infection, and wound dehiscence; however, negative pressure wound therapy had no beneficial effect on the length of hospital stay compared with conventional wound dressings in subjects with closed incisions in orthopaedic trauma surgery. Further studies are required to validate these findings.

Adherence to Guidelines for the Administration of Intraoperative Antibiotics in a Nationwide US Sample

IMPORTANCE

Despite widespread adherence to Surgical Care Improvement Project antibiotic measures, prevention of surgical site infections (SSIs) remains a clinical challenge. Several components of perioperative antibiotic prophylaxis guidelines are incompletely monitored and reported within the Surgical Care Improvement Project program.

OBJECTIVES

To describe adherence to each component of perioperative antibiotic prophylaxis guidelines in regard to procedure-specific antibiotic choice, weight-adjusted dosing, and timing of first and subsequent administrations in a nationwide, multicenter cohort of patients undergoing noncardiac surgery.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included adult patients undergoing general, urological, orthopedic, and gynecological surgical procedures involving skin incision between January 1, 2014, and December 31, 2018, across 31 academic and community hospitals identified within the Multicenter Perioperative Outcomes Group registry. Data were analyzed between April 2 and April 21, 2021.

MAIN OUTCOMES AND MEASURES

The primary end point was overall adherence to Infectious Diseases Society of America guidelines, including (1) appropriateness of antibiotic choice, (2) weight-based dose adjustment, (3) timing of administration with respect to surgical incision, and (4) timing of redosing when indicated. Data were analyzed using mixed-effects regression to investigate patient, clinician, and institutional factors associated with guideline adherence.

RESULTS

In the final cohort of 414 851 encounters across 31 institutions, 51.8% of patients were women, the mean (SD) age was 57.5 (15.7) years, 1.2% of patients were of Hispanic ethnicity, and 10.2% were Black. In this cohort, 148 804 encounters (35.9%) did not adhere to guidelines: 19.7% for antibiotic choice, 17.1% for weight-adjusted dosing, 0.6% for timing of first dose, and 26.8% for redosing. In adjusted analyses, overall nonadherence was associated with emergency surgery (odds ratio [OR], 1.35; 95% CI, 1.29-1.41; P < .001), surgery requiring blood transfusions (OR, 1.30; 95% CI, 1.25-1.36; P < .001), off-hours procedures (OR, 1.08; 95% CI, 1.04-1.13; P < .001), and procedures staffed by a certified registered nurse anesthetist (OR, 1.14; 95% CI, 1.11-1.17; P < .001). Overall adherence to guidelines for antibiotic administration improved over the study period from 53.1% (95% CI, 52.7%-53.5%) in 2014 to 70.2% (95% CI, 69.8%-70.6%) in 2018 (P < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, although adherence to perioperative antibiotic administration guidelines improved over the study period, more than one-third of surgical encounters remained discordant with Infectious Diseases Society of America recommendations. Future quality improvement efforts targeting gaps in practice in relation to guidelines may lead to improved adherence and possibly decreased SSIs.

Perioperative Interventions to Reduce Surgical Site Infections: A Review

Surgical site infections (SSIs) contribute to increased health care costs and morbidity after procedures as well as prolonged length of stay. Perioperative personnel can use a variety of interventions to help reduce SSI incidence; however, all strategies are not effective for all patients (eg, antibiotic prophylaxis). Results of randomized controlled trials show that some SSI reduction strategies are generally effective, including preoperative skin antisepsis with an alcohol-based agent, closing surgical wounds with triclosan-coated suture, and applying a negative pressure wound therapy device to open and closed wounds. Study results do not show that irrigating clean wounds with crystalloid solutions containing antibiotics or routinely using plastic drapes with or without impregnated iodophor or silver nylon-impregnated dressings significantly reduces SSI incidence. Perioperative leaders should support the implementation of strategies to prevent SSIs and work with interdisciplinary team members to develop an SSI prevention bundle that will meet the needs of their patients.

Randomized Trial of Dilute Povidone-Iodine Soak and Scrub for Orthopaedic Foot and Ankle Surgery

BACKGROUND

There is no consensus as to which skin antiseptic solution is most effective at reducing infection following orthopaedic foot and ankle surgery. The purpose of this study is to determine if the addition of a dilute povidone-iodine soak and scrub to a standard preparation with alcohol and chlorhexidine decreases positive bacterial culture rates from the hallux nailfold.

METHODS

In this prospective, randomized controlled trial, 242 subjects undergoing orthopaedic foot and ankle surgery were randomized to one of 2 groups. The control group received our standard 2-step skin antiseptic preparation of an alcohol scrub (step 1) followed by chlorhexidine/alcohol paint (step 2). The intervention group received a 3-minute dilute povidone-iodine soak and scrub followed by that same standard 2-step skin preparation. Immediately before skin incision, culture swabs were taken from the hallux nailfold of both groups.

RESULTS

Of the 257 subjects enrolled and randomized, 242 (94.2%) completed the study, satisfying the a priori sample size requirement of 242 subjects. There were no crossovers between groups. There were no differences in baseline characteristics between groups (P > .05 for each). There was no difference in bacterial growth rates between groups (26.8% growth in the intervention group vs 26.9% growth in the control group, P = .991).

CONCLUSION

The hallux nailfold is one of the most difficult to sterilize areas prior to orthopaedic foot and ankle surgery. This randomized controlled trail found no benefit to adding a 3-minute dilute povidone-iodine soak and scrub to a standard skin preparation with alcohol and chlorohexidine.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Interventions to reduce the incidence of surgical site infection in colorectal resections: systematic review with multicomponent network meta-analysis (INTRISSI): study protocol

OBJECTIVE

To assess the relative contribution of intravenous antibiotic prophylaxis, mechanical bowel preparation, oral antibiotic prophylaxis, and combinations thereof towards the reduction of surgical site infection (SSI) incidence in elective colorectal resections.

METHODS AND ANALYSIS

A systematic search of randomised controlled trials comparing interventions to reduce SSI incidence will be conducted with predefined search terms in the following databases: MEDLINE, LILACS, Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews (CDSR). Additionally, several online databases will be searched for ongoing trials, and conference proceedings and reference lists of retrieved articles will be hand searched. The title-abstract screening will be partly performed by means of a semiautomated supervised machine learning approach, which will be trained on a subset of the identified titles and abstracts identified through traditional screening methods.The primary analysis will be a multicomponent network meta-analysis, as we expect to identify studies that investigate combinations of interventions (eg, mechanical bowel preparation combined with oral antibiotics) as well as studies that focus on individual components (mechanical bowel preparation or oral antibiotics). By means of a multicomponent network meta-analysis, we aim at estimating the effects of the separate components along the effects of the observed combinations. To account for between-trial heterogeneity, a random-effect approach will be combined with inverse variance weighting for estimation of the treatment effects. Associated 95% CIs will be calculated as well as the ranking for each component in the network using P scores. Results will be visualised by network graphics and forest plots of the overall pairwise effect estimates. Comparison-adjusted funnel plots will be used to assess publication bias.

ETHICS AND DISSEMINATION

Ethical approval by the Ethical Committee of the Medical Faculty of the Martin-Luther-University Halle-Wittenberg (ID of approval: 2021-148). Results shall be disseminated directly to decision-makers (eg, surgeons, gastroenterologists, wound care specialists) by means of publication in peer-reviewed journals, presentation at conferences and through the media (eg, radio, TV, etc).

PROSPERO REGISTRATION NUMBER

CRD42021267322.

Analysis of incidence of postoperative wound infection in closed fractures treated by surgical fixation - A prospective study

Background

In orthopaedic surgery where metallic implants are used, surgical site infection (SSI) is a significant complication as it increases the postoperative morbidity and mortality, prolongs hospital stay, and increases the hospital costs. Therefore, understanding the incidence of SSI in various healthcare settings would help us analyse the contributing factors and improve healthcare. Since the rates of SSI in various orthopaedic settings in India are lacking, this study aimed at analysing them and various associated factors in a tertiary medical institute in India.

Materials and methods

This study was a prospective cohort study carried out on 100 orthopaedic patients who underwent surgical fixation for closed fractures, with a follow-up period of one year. The incidence of SSI and the factors associated with them were analysed.

Results

The overall incidence of SSI in our study was 5% (5 cases). The maximum incidence was seen in the age group 51–60 years (40% of the infections). Regarding the duration of preoperative hospital stay, the incidence of SSI was 6.85% when the patients stayed for more than 10 days, whereas the incidence was only 1.66% when the patients stayed for less than or equal to 10 days. Among the diabetics, the incidence of infection was found to be 7.69% (1 out of 13 diabetics). Regarding the operative duration, while cases which took more than 1.5 hours of operative duration had the highest infection rate (60% of the infections), none of the cases which took less than an hour to operate got infected. Among the infective organisms isolated, 60% cases had Staphylococcus aureus, 20% had Proteus vulgaris and another 20% had Klebsiella pneumoniae infection.

Conclusions

Age greater than 50 years, a prolonged preoperative hospital stay more than 10 days, presence of diabetes, a prolonged surgical procedure more than 1.5 hours, and were found to be at a higher risk of SSI in our study.

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Surgical site infection (SSI) in orthopaedic surgery can lead to chronic infection or osteomyelitis.

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Specific data about SSI in orthopaedics in India are lacking.

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Our study highlighted the SSI related factors in orthopaedics in India.

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Higher age, longer preoperative hospital stay, prolonged surgical procedure and diabetes were found associated.

Pharmaceutical properties of a tinted formulation of a biguanide antiseptic agent, olanexidine gluconate

Olanexidine gluconate-containing preoperative antiseptic (OLG-C) is colorless, which makes it difficult to determine its area of application. To overcome this drawback, we realized a stable orange-tinted antiseptic (OLG-T) by adding new additives to OLG-C and investigated its pharmaceutical properties compared with OLG-C and povidone iodine (PVP-I). We evaluated the influence of the additives on the antimicrobial activity and adhesiveness of medical adhesives to OLG-T-applied skin by in vitro time-kill/ex vivo micropig skin assays and a peel test using excised micropig skin, respectively. In the in vitro time-kill assay, the bactericidal/fungicidal activity of OLG-T and OLG-C were equivalent. In the ex vivo micropig skin assay, their fast-acting and persistent bactericidal activities against vancomycin-resistant Enterococcus faecalis were higher than that of PVP-I. In the peel test, the adhesion force of the incise drape and the amount of stripped corneocytes on the peeled drape were comparable between OLG-T- and OLG-C-applied skin, but both were less than those of PVP-I-applied skin. The drapes for OLG-T- and OLG-C-applied skin had moderate adhesion force, and the drape-related injuries were expected to be weak. These results suggest that OLG-T performs no worse than OLG-C in terms of its antimicrobial activity and medical adhesive compatibility. Therefore, we expect OLG-T to lead to more convenient preoperative skin preparation and further contribute to lowering SSI rates.

Seksaka M, F. Balata G. Antibiotic overuse in obstetric and gynecologic procedures at Zagazig university hospitals: A prospective observational study

Surgical site infection (SSI) constitutes a major problem in healthcare in terms of healthcare cost, morbidity and mortality. Surgical antibiotic prophylaxis (SAP) is one of the effective strategies for SSI prevention. Poor adherence to SAP guidelines across different countries has been observed. Misuse of prophylactic antibiotics threatens patient safety and leads to an increase in the acquisition of antibiotic resistance. The aim of this study was to assess the utilization of SAP in obstetric and gynecologic procedures in terms of indication for prophylaxis, antibiotic selection, timing of administration and prophylaxis duration. A prospective observational study was conducted at the obstetrics and gynecology department of Zagazig University Hospital during the period from January 2020 to June 2020. Medical records of 264 women were recorded and evaluated. The American Society of Health-System Pharmacists (ASHP) therapeutic guidelines, World Health Organization (WHO) recommendations and The American College of Obstetricians and Gynecologists (ACOG) practice bulletin were used for data evaluation and hence women were stratified into two groups. For women who underwent procedures in which guidelines recommended the use of SAP (200 patients; 75.75%), 198 women (99%) received preoperative prophylaxis. None of women (0%) received the recommended first line antibiotic by guidelines while the most commonly used prophylactic antibiotics were Cefotaxime (86 patients; 43.43%) and Ampicillin-sulbactam (62 patients; 31.31%). Preoperative antibiotic prophylaxis timing was 0-60 minutes before skin incision. All women received postoperative prophylaxis that extended to an average of 7 days. Regarding the other group who underwent procedures in which prophylactic antibiotics weren’t recommended by guidelines (64 patients; 24.24%), 37 women (57.81%) followed the guidelines and didn’t receive SAP while 27 women (42.18%) received SAP. Poor adherence to guidelines recommendations regarding prophylactic antibiotic selection and prophylaxis duration was observed. High utilization rate of prophylactic antibiotics in procedures that didn’t require their use was reported..

Update on the epidemiology of healthcare-acquired bacterial infections: focus on complicated skin and skin structure infections

Healthcare-associated infections (HCAIs) are a threat to patient safety and cause substantial medical and economic burden in acute care and long-term care facilities. Risk factors for HCAIs include patient characteristics, the type of care and the setting. Local surveillance data and microbiological characterization are crucial tools for guiding antimicrobial treatment and informing efforts to reduce the incidence of HCAI. Skin and soft tissue infections, including superficial and deep incisional surgical site infections, are among the most frequent HCAIs. Other skin and soft tissue infections associated with healthcare settings include vascular access site infections, infected burns and traumas, and decubitus ulcer infections.

Surgical and remote site infections after reconstructive surgery of the head and neck: A risk factor analysis

The aim of this study was to identify risk factors for surgical (SSI) and remote site (RSI) infections, pathogens and antibiotic resistances in patients after pedicled and free flap reconstruction in the head and neck area. SSI criteria implicated infections affecting superficial or deep tissue in the flap area with purulent discharge, fistula, abscess formation and local infections signs. RSI criteria were defined as infections remote from the surgical site presenting with systemic symptoms like fever, leucocytosis, increase in C-reactive protein, purulent tracheobronchial secretion or deterioration of blood gases. Focus adequate specimen sampling and aerobic and anaerobic incubation and cultivation was performed. Epidemiological data, factors directly related to surgery or reconstruction, perioperative antibiotic regimen, length of stay, autologous blood transfusion and microbiological aspects were retrospectively analysed in 157 patients. 10.8% of patients presented SSI, 12.7% RSI. Cultivated bacteria were sampled from flap sites, blood cultures, central catheters and sputum including mainly gram-negative bacteria (70.3%) being frequently resistant against penicillin (85%) and third generation cephalosporine derivates (48%). Autologous blood transfusion (p = 0.018) and perioperative clindamycin use (p = 0.002) were independent risk factors for overall (SSI and RSI combined) infections. Prior radiation (p = 0.05), autologous blood transfusion (p = 0.034) and perioperative clindamycin use (p = 0.004) were predictors for SSIs. ASA >2 (p = 0.05) was a risk factor for remote site infections and prolonged ICU stay (p = 0.002) was associated with overall infections, especially in irradiated patients. Efforts need to be made in improving patient blood management, antibiotic stewardship and accurate postoperative care to avoid postoperative infections after head and neck reconstructive surgery.

Quality Initiative for the Administration of Vancomycin Prophylaxis in Penicillin-Allergic Neurosurgery Patients

Introduction

Vancomycin may be used as an alternative perioperative antibiotic for penicillin-allergic patients but follows a different infusion timing. At the institution presented herein, noncompliance with recommended vancomycin infusion timing has been hypothesized to contribute toward increased risk of surgical site infections and avoidable expenditures. The objective of this project was to utilize the Performance Improvement In Action methodology to identify, address, and solve the problem of vancomycin administration timing.

Methodology

This study took place at a multi-hospital, urban academic medical center. The protocol was developed by neurosurgery and anesthesia faculty, advanced practice providers, nursing, and pharmacy. Timing of the following points was recorded: initial order, order release, pharmacy verification, vancomycin infusion, and surgical incision. Fifty consecutive penicillin-allergic patients undergoing neurosurgical intervention were prospectively enrolled. Data comparison was made between the pilot and retrospective review cohorts.

Results

The pilot cohort achieved correct administration of vancomycin in 100% of cases. Average infusion start time prior to incision increased by 257% (p<0.0001).

Conclusions

This study demonstrates a departmental capacity for optimized timing of vancomycin infusions, in a budget- and workflow-neutral process, while reducing inappropriate administration. In the future, this protocol may be scaled to additional departments and institutions to appropriately and efficiently administer perioperative vancomycin and mitigate the risk for surgical site infections.

Comparative efficacy of 0.2% chlorhexidine and 10% Betadine for perioral skin disinfection prior to oral surgical procedures: a clinical trial

BACKGROUND

Surgical site infection (SSI) is a possible postoperative complication. Preoperative application of antiseptics on the surgical site can decrease the rate of SSIs.

AIM

This study aimed to compare the efficacy of 0.2% chlorhexidine (CHX) and 10% Betadine (povidone-iodine) for perioral skin disinfection prior to oral surgical procedures.

METHODS

This clinical trial (IRCT20181017041365N1) (registration date: 2019/05/04) evaluated 57 male patients who were randomly selected among those presenting to the Periodontology Department of Ahvaz Jundishapur University. Baseline microbial samples were collected from the perioral skin at the right and left sides of the face in each patient by sterile swabs. Next, the perioral area was disinfected with 10% Betadine in the right side and 0.2% CHX in the left side. Secondary microbial samples were then collected. Wilcoxon matched-pairs signed-ranks and Mann-Whitney test were used to compare the colony counts. The significance level was set at p ≤ 0.05. Data were analyzed with the Stata program, version15.1.

RESULTS

The bacterial colony count was 3147 (314,700) in the Betadine and 3139 (313,900) in the CHX group at baseline (P = 0.86). These values changed to 1196 (119,600) in the Betadine (P < 0.001) and 857 (85,700) in the CHX (P < 0.001) group after disinfection. A significant difference was found in colony count between the CHX and Betadine groups after intervention (P = 0.0001).

CONCLUSION

According to the results, 0.2% CHX has higher antimicrobial efficacy than 10% Betadine for perioral disinfection prior to oral surgical procedures.

TRIAL REGISTRATION

IRCT20181017041365N1. Registered on 2019/05/04.

Incidence and Predictors of Surgical Site Infection Complications in Diabetic Patients Undergoing Lower Limb Amputation

BACKGROUND

Surgical site infections (SSIs) following lower extremity amputations (LEAs) are a major cause of patient morbidity and mortality. The objectives of this study are to investigate the annual incidence of SSI and risk factors associated with SSI after LEA in diabetic patients.

METHODS

LEAs performed on diabetic patients between 2005 and 2017 were retrospectively analyzed from the American College of Surgeons National Surgical Quality Improvement Program database. Incidence rates were calculated and analyzed for temporal change. Multivariable logistic regression was conducted to identify the independent predictors of SSIs in LEA.

RESULTS

In 21,449 diabetic patients, the incidence of SSIs was 6.8% after LEA, with an overall decreasing annual trend (P = 0.013). Amputation location (below-knee in reference to above-knee) [OR (95% CI): 1.35 (1.20 - 1.53), P <0.001], smoking [OR (95% CI): 1.25 (1.11 - 1.41), P <0.001)], female sex [OR (95% CI): 1.16 (1.03 - 1.30)], preoperative sepsis [OR (95% CI): 1.24 (1.10 - 1.40), P <0.001], P = 0.013], emergency status [OR (95% CI): 1.38 (1.17 - 1.63), P <0.001], and obesity [OR (95% CI): 1.59 (1.12 - 2.27), P = 0.009] emerged as independent predictors of SSIs, while moderate/severe anemia emerged as a risk-adjusted protective factor [OR (95% CI): 0.75 (0.62 - 0.91), P = 0.003]. Sensitivity analysis found that moderate/severe anemia, not body mass index (BMI) class, remained a significant risk factor in the development of SSIs in below-the-knee amputations; in contrast, higher BMI, not preoperative hematocrit, was significantly associated with an increased risk for SSI in above-the-knee amputations.

CONCLUSIONS

The incidence of SSIs after LEA in diabetic patients is decreasing. Overall, below-knee amputation, smoking, emergency status, and preoperative sepsis appeared to be associated with SSIs. Obesity increased SSIs in above-the-knee amputations, while moderate/severe preoperative anemia appears to protect against below-the-knee SSIs. Surgeons should take predictors of SSI into consideration while optimizing care for their patients, and future studies should investigate the role of preoperative hematocrit correction and how it may influence outcomes positively or negatively.

The Use of Mobile Thermal Imaging and Deep Learning for Prediction of Surgical Site Infection

The ability to detect surgical site infections (SSI) is a critical need for healthcare worldwide, but is especially important in low-income countries, where there is limited access to health facilities and trained clinical staff. In this paper, we present a new method of predicting SSI using a thermal image collected with a smart phone. Machine learning algorithms were developed using images collected as part of a clinical study that included 530 women in rural Rwanda who underwent cesarean section surgery. Thermal images were collected approximately 10 days after surgery, in conjunction with an examination by a trained doctor to determine the status of the wound (infected or not). Of the 530 women, 30 were found to have infected wounds. The data were used to develop two Convolutional Neural Net (CNN) models, with special care taken to avoid overfitting and address the problem of class imbalance in binary classification. The first model, a 6-layer naïve CNN model, demonstrated a median accuracy of AUC=0.84 with sensitivity=71% and specificity=87%. The transfer learning CNN model demonstrated a median accuracy of AUC=0.90 with sensitivity =95% and specificity=84%. To our knowledge, this is the first successful demonstration of a machine learning algorithm to predict surgical infection using thermal images alone.Clinical Relevance- This work establishes a promising new method for automated detection of surgical site infection.

Use of Convolutional Neural Nets and Transfer Learning for Prediction of Surgical Site Infection from Color Images

One of the greatest concerns in post-operative care is the infection of the surgical wound. Such infections are a particular concern in global health and low-resource areas, where microbial antibiotic resistance is often common. In order to help address this problem, there is a great interest in developing simple tools for early detection of surgical wounds. Motivated by this need, we describe the development of two Convolutional Neural Net (CNN) models designed to detect an infection in a surgical wound using a color image taken from a mobile device. These models were developed using image data collected from a clinical study with 572 women in Rural Rwanda, who underwent Cesarean section surgery and had photos taken approximately 10 days after surgery. Infected wounds (N=62) were diagnosed by a trained doctor through a physical exam. In our model development, we observed a trade-off between AUC accuracy and sensitivity, and we chose to optimize for sensitivity, to match its use as a screening tool. Our naïve CNN model, with a limited number of convolutions and parameters, achieved median AUC = 0.655, true positive rate sensitivity = 0.75, specificity = 0.58, classification accuracy = 0.86. The second CNN model, developed with transfer learning using the Resnet50 architecture, produced a median AUC = 0.639 sensitivity = 0.92, specificity = 0.18, and classification accuracy 0.82. We discuss the specific training and optimization methods used to compensate for significant class imbalance and maximize sensitivity.

Worldwide incidence of surgical site infections in general surgical patients: A systematic review and meta-analysis of 488,594 patients

BACKGROUND

Establishing worldwide incidence of general surgical site infections (SSI) is imperative to understand the extent of the condition to assist decision-makers to improve the planning and delivery of surgical care. This systematic review and meta-analysis aimed to estimate the worldwide incidence of SSI and identify associated factors in adult general surgical patients.

MATERIALS AND METHODS

A systematic review was undertaken using MEDLINE (Ovid), CINAHL (EBSCO), EMBASE (Elsevier) and the Cochrane Library to identify cross-sectional, cohort and observational studies reporting SSI incidence or prevalence. Studies of less than 50 participants were excluded. Data extraction and quality appraisal were undertaken independently by two review authors. The primary outcome was cumulative incidence of SSI occurring up to 30 days postoperative. The secondary outcome was the severity/depth of SSI. The I² statistic was used to explore heterogeneity. Random effects models were used in the presence of substantial heterogeneity. Subgroup, meta-regression sensitivity analyses were used to explore the sources of heterogeneity. Publication bias was assessed using Hunter's plots and Egger's regression test.

RESULTS

Of 2091 publications retrieved, 62 studies were included. Of these, 57 were included in the meta-analysis across six anatomical locations with 488,594 patients. The pooled 30-day cumulative incidence of SSI was 11% (95% CI 10%-13%). No prevalence data were identified. SSI rates varied across anatomical location, surgical approach, and priority (i.e., planned, emergency). Multivariable meta-regression showed SSI is significantly associated with duration of surgery (estimate 1.01, 95% CI 1.00-1.02, P = .014).

CONCLUSIONS

and Relevance: 11 out of 100 general surgical patients are likely to develop an infection 30 days after surgery. Given the imperative to reduce the burden of harm caused by SSI, high-quality studies are warranted to better understand the patient and related risk factors associated with SSI.

Increasing rates of laparoscopic gastrointestinal surgery and decreasing rates of surgical site infections: an observational study in Japan from 2012-2017

BACKGROUND

Surgical site infections (SSI) are the most common healthcare-associated infection, and gastrointestinal surgery is frequently followed by a high incidence of SSI. Epidemiological analysis of the temporal trends in SSI following gastrointestinal surgery has yet to be performed in Japan. Our purpose was to descriptively investigate these trends.

METHODS

Extracting national surveillance data from the Japan Nosocomial Infections Surveillance (JANIS) system, we analyzed the frequency of SSI events following gastrointestinal surgery, which consisted of seven surgical procedures, from 2012-2017. We calculated the standardized infection ratio to compute risk-adjusted SSI frequency, and used the trend test to detect time-dependent changes.

RESULTS

The frequency of SSI events, except for those associated with surgery of the upper gastrointestinal tract, revealed a decreasing time-dependent trend. The use of laparoscopic surgery increased dramatically over time (p < 0.01 for the six applicable surgical sites), while the frequency of SSI events during laparoscopic surgery remained unchanged.

CONCLUSIONS

The increasing use of laparoscopic surgery was identified, and the observation coincided with the decreasing trend in SSI, especially in lower gastrointestinal tract surgery. If the relationship is causal, the overall SSI incidence among previously healthy individuals is expected to decrease, because the use of laparoscopic surgery has large growth potential in Japan.

Clinically relevant features for predicting the severity of surgical site infections

Surgical site infections are hospital-acquired infections resulting in severe risk for patients and significantly increased costs for healthcare providers. In this work, we show how to leverage irregularly sampled preoperative blood tests to predict, on the day of surgery, a future surgical site infection and its severity. Our dataset is extracted from the electronic health records of patients who underwent gastrointestinal surgery and developed either deep, shallow or no infection. We represent the patients using the concentrations of fourteen common blood components collected over the four weeks preceding the surgery partitioned into six time windows. A gradient boosting based classifier trained on our new set of features reports, respectively, an AUROC of 0:991 and 0:937 at predicting a postoperative infection and the severity thereof. Further analyses support the clinical relevance of our approach as the most important features describe the nutritional status and the liver function over the two weeks prior to surgery.

Novel Antibiotic-Irrigating Wound Protector Reduces Infectious Complications in Robot-Assisted Radical Cystectomy with Extracorporeal Urinary Diversion

OBJECTIVE

To determine whether use of an antibiotic-irrigating wound protector (AWP) reduces infectious complications after robotic radical cystectomy with extracorporeal urinary diversion (RCUD).

METHODS

A prospectively maintained bladder cancer database was queried for patients undergoing robotic RCUD at a tertiary referral center one year prior to implementing an AWP and one year after (2018-2020). All diversions were performed extra-corporally. 92 patients total. 46 consecutive patients using a traditional wound protector (TWP) and 46 consecutive with an AWP. Infections were classified as symptomatic urinary tract infection, blood stream infection, and surgical site infection. The incidence of infectious complications at 30- and 90-days were compared.

RESULTS

Baseline patient characteristics between the 2 groups showed no statistically significant differences. The overall complication rate was 65.2% in the TWP group and 26.1% in the AWP group at 30-days, and 67.4% vs 30.4% at 90-days. Focusing on infections, the 30-day complication rate was 30.4% in the TWP group compared to 6.5% in the AWP group (P =.003). This pattern persisted at 90-days with 37.0% in the TWP group compared to 6.5% in the AWP group (P =.004). Most complications were symptomatic UTI and blood stream infections, 14/24 (58%), requiring parenteral antibiotic treatment.

CONCLUSION

We provide preliminary data showing use of an AWP can reduce infectious complications after RCUD. While larger prospective studies are warranted, our findings are a significant step towards decreasing morbidity of an already highly morbid procedure.

Timing of Preoperative Antibiotic Prophylaxis and Surgical Site Infection: TAPAS, An Observational Cohort Study

OBJECTIVE

To test the hypothesis that surgical site infection (SSI) risk differs, after administration of surgical antibiotic prophylaxis (SAP) within 60-30 or 30-0 minutes before incision.

BACKGROUND

The importance of appropriate timing of SAP before surgery has long been recognized. However, available evidence is contradictive on the best timing within a 60-0 minutes time interval before incision. Here, we aim to evaluate previous contradictions with a carefully designed observational cohort.

METHODS

An observational cohort study was conducted in a Dutch tertiary referral center. For 2 years, consecutive patients with SAP indication undergoing general, orthopedic, or gynecologic surgery were followed for the occurrence of superficial and deep SSI as defined by the Center of Disease Control and Prevention. The association between timing of SAP and SSI was assessed using multivariable logistic regression.

RESULTS

After 3001 surgical procedures, 161 SSIs were detected. In 87% of the procedures, SAP was administered within 60 minutes before incision. Only antibiotics with short infusion time were used. Multivariable logistic regression indicated there was no conclusive evidence of a difference in SSI risk after SAP administration 60-30 minutes or 30-0 minutes before incision [odds ratio: 0.82; 95% confidence interval (0.57-1.19)].

CONCLUSIONS

For SAP with short infusion time no clear superior timing interval within the 60-minute interval before incision could be identified in this cohort. We were unable to reproduce differences in SSI risk found in earlier studies.

Evaluation of a Broad-Spectrum Partially Automated Adverse Event Surveillance System: A Potential Tool for Patient Safety Improvement in Hospitals With Limited Resources

OBJECTIVE

The aim of the study was to evaluate the sensitivity and resource efficiency of a partially automated adverse event (AE) surveillance system for routine patient safety efforts in hospitals with limited resources.

METHODS

Twenty-eight automated triggers from the hospital information system's clinical and administrative databases identified cases that were then filtered by exclusion criteria per trigger and then reviewed by an interdisciplinary team. The system, developed and implemented using in-house resources, was applied for 45 days of surveillance, for all hospital inpatient admissions (N = 1107). Each trigger was evaluated for its positive predictive value (PPV). Furthermore, the sensitivity of the surveillance system (overall and by AE category) was estimated relative to incidence ranges in the literature.

RESULTS

The surveillance system identified a total of 123 AEs among 283 reviewed medical records, yielding an overall PPV of 52%. The tool showed variable levels of sensitivity across and within AE categories when compared with the literature, with a relatively low overall sensitivity estimated between 21% and 44%. Adverse events were detected in 23 of the 36 AE categories defined by an established harm classification system. Furthermore, none of the detected AEs were voluntarily reported.

CONCLUSIONS

The surveillance system showed variable sensitivity levels across a broad range of AE categories with an acceptable PPV, overcoming certain limitations associated with other harm detection methods. The number of cases captured was substantial, and none had been previously detected or voluntarily reported. For hospitals with limited resources, this methodology provides valuable safety information from which interventions for quality improvement can be formulated.

Evaluation of the costing methodology of published studies estimating costs of surgical site infections: A systematic review

OBJECTIVES

Surgical site infections (SSIs) are associated with increased length of hospitalization and costs. Epidemiologists and infection control practitioners, who are in charge of implementing infection control measures, have to assess the quality and relevance of the published SSI cost estimates before using them to support their decisions. In this review, we aimed to determine the distribution and trend of analytical methodologies used to estimate cost of SSIs, to evaluate the quality of costing methods and the transparency of cost estimates, and to assess whether researchers were more inclined to use transferable studies.

METHODS

We searched MEDLINE to identify published studies that estimated costs of SSIs from 2007 to March 2021, determined the analytical methodologies, and evaluated transferability of studies based on 2 evaluation axes. We compared the number of citations by transferability axes.

RESULTS

We included 70 studies in our review. Matching and regression analysis represented 83% of analytical methodologies used without change over time. Most studies adopted a hospital perspective, included inpatient costs, and excluded postdischarge costs (borne by patients, caregivers, and community health services). Few studies had high transferability. Studies with high transferability levels were more likely to be cited.

CONCLUSIONS

Most of the studies used methodologies that control for confounding factors to minimize bias. After the article by Fukuda et al, there was no significant improvement in the transferability of published studies; however, transferable studies became more likely to be cited, indicating increased awareness about fundamentals in costing methodologies.

Use of Vancomycin Mixed Bone Graft and Vancomycin Mixed Saline Wash Before Wound Closure Reduces the Rate of Infection in Lumbar Spine Fusion Surgery

This study aims to evaluate whether surgical site vancomycin mixed in bone grafts and local vancomycin mixed in normal saline wash before wound closure decrease the infection rates in patients undergoing lumbar spinal instrumentation and posterolateral fusion. A retrospective study was performed on cases between 2017 and 2019, who underwent lumbar spine instrumentation and posterolateral fusion for lumbar canal stenosis or listhesis. The routine prophylactic procedures were performed in all patients as per institutional protocol. Patients' records were analysed and categorised into two groups, the vancomycin group (VG), where vancomycin mixed in bone graft and normal saline wash was used at the surgical site, and the control group (CG), where vancomycin was not used. The study included 63 patients, 31 in VG and 32 in CG. There is no statistical difference in age, sex, and diabetes mellitus in both groups. A total of seven cases were infected, six in CG (6/32) and one in VG (1/31). Out of six infections in CG, three patients had diabetes and four infected cases underwent surgery for debridement. In VG, the only single case got infected and treated with intravenous antibiotics. We found that the use of vancomycin added to the bone graft and normal saline in posterior lumbar spinal instrumentation and posterolateral fusion is associated with significantly lower rates of infection (p value=0.049).

Inflammatory blood parameters as prognostic factors for surgical site infection after primary hip or knee arthroplasty: a systematic review protocol

INTRODUCTION

Surgical site infection (SSI) is a potential complication of surgical procedure. SSI after implant surgery is a disaster both for patients and surgeons. Although predictive tools for SSI are available, none of them estimate early infection based on inflammatory blood parameters. The inflammatory process can be measured using several parameters including interleukin-6, C reactive protein, neutrophil to lymphocyte ratio, white cell count, erythrocyte sedimentation rate or procalcitonin. This systematic review aims to determine whether inflammatory blood parameters could be used as significant predictive factors for SSI after primary hip or knee arthroplasty.

METHODS AND ANALYSIS

A systematic review of randomised controlled trials, cross-sectional studies, case-control studies and cohort studies, published in English, will be searched in the following electronic bibliographic databases: MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials and Web of Science. Studies performed in adult patients of all ages who underwent knee or hip arthroplasty, studies containing data on the risk/prognostic factors for preknee or postknee or hip arthroplasty SSI and studies with a minimum follow-up of 30 days after surgery will be included. A standardised form will be used to extract data from the included studies comprising study characteristics, participant characteristics, details of the intervention, study methodology and outcomes. Quality Assessment of Diagnostic Accuracy tool, second version, and Standards for Reporting of Diagnostic Accuracy Studies checklist will be used to assess risk of bias. Heterogeneity will be assessed using Cochran χ² statistic and I² statistics where applicable. Grading of Recommendations Assessment, Development and Evaluation and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance will be used to report findings.

ETHICS AND DISSEMINATION

No ethics approval is required. The findings will be disseminated at national and international scientific sessions, also to be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020147925.

Bacterial DNA screening to characterize surgical site infection risk in orthopaedic patients

Purpose

To provide an initial characterization of relevant bacterial DNA profiles for patients undergoing closed-fracture fixation or total joint arthroplasties.

Patients and methods

Swabs were collected and analyzed using Polymerase Chain Reaction from adult patients undergoing closed-fracture fixation or total shoulder, knee, or hip arthroplasties.

Results

Bacterial DNA profiles varied across the different orthopaedic patient populations, and produced uncharacteristic profile shifts with direct relevance to each clinical infection.

Conclusion

Findings provide a foundational dataset regarding bacterial colonization of relevant anatomic sites that can act as sources of surgical site infections for patients.

Magnetic device in reduced port and single port bariatric surgery: First 170 cases experience

INTRODUCTION

Magnetic devices have been successfully used in bariatric surgery. To the date, the only reported use of the magnet was for liver retraction. Our purpose in this study is to demonstrate the safety and viability of using a magnetic system in different steps in single port and reduced port bariatric surgery.

METHODS

Prospective and observational study was performed. Patients older than 18 years, undergoing primary laparoscopic sleeve gastrectomy (SG), one-anastomosis gastric bypass (OAGB), and Roux-en-Y gastric bypass (RYGB) or revisional surgery by single-port or reduced-port approach between July 2020 and June 2021 were included.

RESULTS

A total of 170 patients (mean BMI, 41.47kg/m2; mean age 36.92 yrs) completed laparoscopic bariatric surgery (54 single-port sleeve gastrectomy [SPSG], 16 reduced-port SG, 83 RYGB, 4 OAGB and 14 revision surgeries), using the magnetic surgical system in different steps of the surgery. Mean surgical time for SPSG and reduced-port SG was 65.52min and 59.36min respectively; and for RYGB 74.19min, OAGB 70.98min, and revisional surgeries 88.38min. As for intraoperative complications, 2.94% mild liver laceration without significant bleeding was reported. There were no 30-day mortalities and no major complications.

CONCLUSION

Magnetic assistance in single-port and reduced-port bariatric surgery is an innovative technique. With this prospective study we attempt to demonstrate the safety profile and potential uses that may improve the implementation of new surgical approaches in bariatric surgery.

Incidence and Risk Factors for Surgical Site Infection following Emergency Cesarean Section: A Retrospective Case-Control Study

OBJECTIVE

To assess the incidence, risk, and associated factors that contribute to an acquired surgical site infection (SSI) after emergency cesarean section (CS).

METHODS

This retrospective case-control study was conducted in an acute district general hospital in England with 206 patients (101 SSI patients and 105 non-SSI patients) who had an emergency CS in 2017. Grade of surgeon, smoking status, preoperative vaginal swab status (positive or negative), diabetes status, age, body mass index, membrane rupture to delivery interval, and length of surgery were recorded. Risk factors were identified using simple and multiple logistic regression.

RESULTS

Body mass index was significantly associated with SSI (odds ratio, 1.17; 95% confidence interval, 1.11 to 1.24; P < .001). Further, substantive nonsignificant associations were recorded between SSI and patient age and vaginal swab status.

CONCLUSIONS

Body mass index was the only significant risk factor for the development of an SSI after emergency CS, possibly because of the impact of excessive adipose tissue on the immune system and reduced effectiveness of antibiotics. Diabetes status, patient age, and preoperative vaginal swab status were not significantly associated with SSI. Improved guidelines and strategies for managing at-risk patients would enable clinicians to reduce the risk of SSI development. The importance of wound management including frequent wound cleaning, appropriate dressings, dressing changes, and education is highlighted. Future research on larger samples should be conducted to validate these findings.

Risk Stratification for Superficial Surgical Site Infection after Emergency Trauma Laparotomy

Background: Superficial surgical site infections (S-SSIs) are common after trauma laparotomy, leading to morbidity, increased costs, and prolonged length of stay (LOS). Opportunities to mitigate S-SSI risks are limited to the intra-operative and post-operative periods. Accurate S-SSI risk stratification is paramount at the time of operation to inform immediate management. We aimed to develop a risk calculator to aid in surgical decision-making at the time of emergency laparotomy. Methods: A retrospective cohort study of patients requiring emergency trauma laparotomy between 2011 and 2017 at a single, level 1 trauma center was performed. Operative factors, skin management strategy, and outcomes were determined by chart review. Bayesian multilevel logistic regression was utilized to create a risk calculator with variables available upon closure of the laparotomy. Models were validated on a 30% test cohort and discrimination reported as an area under the receiver operating characteristics curve (AUROC). Results: Of 1,322 patients, the majority were male (77%) with median age of 33 years, injured by blunt mechanism (54%), and median injury severity score of 19. Eighty-eight (7%) patients developed an S-SSI. Patients who developed S-SSI had higher final lactate, blood loss, transfusion requirements, and wound classification. Patients with S-SSI more frequently had mesenteric or large bowel injury than those without S-SSI. Superficial SSI was associated with increased complications and prolonged length of stay (LOS). The S-SSI predictive model demonstrated moderate discrimination with an AUROC of 0.69 (95% confidence interval [CI], 0.56-0.81). Parameters contributing the most to the model were damage control laparotomy, full-thickness large bowel injury, and large bowel resection. Conclusion: A predictive model for S-SSI was built using factors available to the surgeon upon index emergency trauma laparotomy closure. This calculator may be used to standardize intra- and post-operative care and to identify high-risk patients in whom to test novel preventative strategies and improve overall outcomes for patients requiring emergency trauma laparotomy.

Evidence of the medical and economic benefits of implementing hygiene measures by a prevention link physician in trauma surgery: Study protocol for a biphasic multicenter prospective interventional pre-post cohort study using a structured intervention bundle development and tools of behavior change management

INTRODUCTION

The German Commission for Hospital Hygiene and Infection Prevention recommends nominating one authorized medical specialist in every medical department as an infection prevention link physician (PLP). It has been roughly described that a PLP serves as a link between the infection prevention team and the respective clinical departments. No detailed evidence about the contribution made by PLPs to the decrease of infection rates is available in Germany. The "HygArzt" project aims to demonstrate the medical and economic benefits of the implementation of hygiene measures by PLP in trauma surgery/orthopedics.

METHODS

A multicenter interventional pre/post cohort study design was chosen. The study will run for a three-year period, including a pre-, post-, and an intervention phase, in four different hospitals, one of which will serve as pilot. A complex intervention containing evidence-based infection control measures will be developed and implemented by a PLP to proof efficacy. After the successful implementation of the preventive measures in the pilot hospital, the concept will be transposed to the three remaining trauma and orthopedic departments to confirm the transferability and generalizability. To enable the PLPs of the non-pilot departments, a subject-specific training program will be developed based on the study results of the pilot hospital and offered to the PLPs.

DISCUSSION

Data are intended to provide evidence that and, if so, to which extent the implementation of specific preventive measures by a medical department-specific PLP is possible and results in a reduction of nosocomial infections in orthopedic surgery and traumatology.

CONTRIBUTION TO THE LITERATURE

The present study describes a novel complex study design to prove the effectiveness of intervention measures for infection prevention. The study design and newly developed methodological approach could serve as a model for similar studies on infection prevention in the future. For the first time, the presented research project "HygArzt" focuses on the implementation of hygiene measures by an infection prevention link physician (PLP) and investigates whether nosocomial infections, especially surgical site infections, can be reduced by the measures implemented.

TRIAL REGISTRATION

German clinical Trials register DRKS-ID:00013,296. Registered on March 5, 2018, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00013296.

Does pulsed lavage reduce the risk of surgical site infection? A systematic review and meta-analysis

BACKGROUND

Surgical site infections (SSIs) remain a significant and common postoperative complication. Whereas most surgeons use some form of wound irrigation during closure, its impact on SSI rates is debated. Preliminary studies in the use of pressurized irrigation, termed pulsed lavage, may have potential benefit to reduce the risk of SSI.

AIM

To perform a systematic review to identify studies that reported SSI rates following surgery, comparing the use of pulsed lavage to controls, following PRISMA guidelines.

METHODS

All study types and those published up to January 1^st, 2021 were included. Odds ratios (ORs) were calculated for each included study using a Mantel-Haenszel statistical analysis, via a random effects model. A sub-analysis on abdominal procedures only was also performed.

FINDINGS

Eleven studies met the inclusion criteria, covering either orthopaedic or general surgery procedures; 1875 patients were included, with 816 patients in the pulsed lavage group and 1059 patients in the control group. Overall study quality was low. There was a significant reduction in the SSI rate with the use of pulsed lavage (odds ratio (OR): 0.39; 95% confidence interval (CI): 0.25-0.62; P < 0.0001). Sub-analysis on abdominal operations only showed further improvement to the SSI rate with pulsed lavage (OR: 0.32; 95% CI: 0.21-0.49; P < 0.0001).

CONCLUSION

Pulsed lavage significantly reduces the rate of SSIs in surgical procedures, the effect being most pronounced in abdominal operations; however, current study quality is low. Randomized controlled trial data are essential to fully assess the potential clinical and financial benefits pulsed lavage can confer to SSI reduction.

The Socioeconomic Impact of Surgical Site Infections

Précis: Surgical site infections are an ever-increasing phenomenon worldwide due to different factors. This brief report aimeds to highlight at a glance, for both physicians and political and institutional leaders, the economic burden of surgical site infections.

Objectives: This brief report aimed to highlight the economic burden of surgical site infections (SSIs).

Methods: A narrative review focusing on this subject has been carried out.

Results: Surgical site infections are responsible for generating important costs. In 2017, a French cohort highlighted a mean cost of each SSI treatment to be around €1,814; the same year, the Centers for Disease Control and Prevention guidelines evaluated the mean cost caused by SSI treatment to be from $10,443 to $25,546 per SSI. This cost depends on many factors including the patient himself and the type of surgery.

Conclusions: Prevention of the risk of infection is, therefore, a profitable concept for surgery that must be integrated within all healthcare managements worldwide.

9-step magnetic assisted conversion from sleeve gastrectomy to roux-en-Y gastric bypass and hiatoplasty by single-port: Case report

RYGB represents one of the best alternatives for weight loss in obese patients achieving a weight loss of up to 60% and a resolution of comorbidities of 70%. Revision surgery contemplates multiple techniques including the conversion from one surgical technique to another, structural changes to the primary technique, among others. GERD is now a long-term problem for patients who have undergone LGS. With this case report, we show the feasibility and viability of making this revisional procedure with magnetic assistance and single-port device. (ClinicalTrials.govNCT04945304). A 32-year-old female patient underwent a SG in September 2018 with a BMI of 30 Kg/m² and no medical history of comorbidities. One year after the surgery the patient reached a BMI of 23,9 Kg/m². In 2020 the multidisciplinary team made a diagnosis of intractable GERD and for that reason, it was decided to perform a conversion surgery to RYGB by single port technique and magnetic assistance. The purpose of this case report is to expose the viability to perform a revisional bariatric surgery with magnetic assistance acting like a second surgical assistant in the steps of the procedure and utilizing a single port device to make fewer before incisions, reduce postoperative pain, length of hospital stay and better cosmesis with a safety approach. We can demonstrate the technical feasibility and safety of performing a conversion surgery of LGS to RYGB and hiatoplasty with magnetic assistance by single port and also demonstrate that the magnetic system serves beyond the liver retraction.

•

Magnetic assistance in bariatric surgery is an innovative tool to achieve excellent results. Some studies demonstrate the good results of utilizing these devices in other fields of surgery.

•

Utilizing a single-port device represents fewer incisions and better cosmesis for the patient without incrementing postoperative complications. With this device, we can reduce postoperative pain, length of hospital stay, and site of infections.

•

Magnetic assistance in other studies demonstrates the safety of utilizing liver magnetic retraction. We show another way to use the magnetic assistance and is acting like a second surgical assistant in other steps of the procedure.

The application value of operating room ventilation with laminar airflow for surgical site infection: A protocol for a systematic review and meta-analysis

BACKGROUND

The presence of biological particles in the air inside operating theatres has the potential to cause severe surgical site infections. Recently, laminar airflow systems have been regarded as a means to reducing surgical site infections using airborne microbes. Still, other publications have argued the benefits of laminar airflow systems, stating the likelihood of adverse effects. Therefore, we will conduct this systematic study to evaluate the applicational value of adopting laminar airflow systems in operating theatres to minimize surgical site infections.

METHODS

Reporting of this study adheres to the guidelines of Preferred Reporting Items for Systematic Review and Meta-analysis Protocols. The authors will perform a systematic search on MEDLINE, Web of Science, EMBASE, the China national knowledge infrastructure, and the Cochrane Library from their commencement until June 2021. The search will identify relevant randomized and non-randomized controlled trials that evaluates the applicational value of using laminar airflow ventilation in surgical theatres to minimize surgical site infections. There are no restrictions on language. Two authors will independently screen the identified studies, perform data extraction, and use an appropriate method to evaluate the bias risk in the included studies.

RESULTS

The work done in the present study will enhance the existing literature on the applicational value of laminar airflow ventilation in surgical theatre to reduce surgical site infections.

CONCLUSION

The outcomes are a reference for healthcare practitioners and patients when making informed decisions regarding care during surgeries.

Incomplete Administration of Intravenous Vancomycin Prophylaxis is Common and Associated With Increased Infectious Complications After Primary Total Hip and Knee Arthroplasty

BACKGROUND

Vancomycin is often used as antimicrobial prophylaxis in patients undergoing total hip or knee arthroplasty. Vancomycin requires longer infusion times to avoid associated side effects. We hypothesized that vancomycin infusion is often started too late and that delayed infusion may predispose patients to increased rates of surgical site infections and prosthetic joint infections.

METHODS

We reviewed clinical data for all primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients at our institution between 2013 and 2020 who received intravenous vancomycin as primary perioperative gram-positive antibiotic prophylaxis. We calculated duration of infusion before incision or tourniquet inflation, with a cutoff of 30 minutes defining adequate administration. Patients were divided into two groups: 1) appropriate administration and 2) incomplete administration. Surgical factors and quality outcomes were compared between groups.

RESULTS

We reviewed 1047 primary THA and TKA patients (524 THAs and 523 TKAs). The indication for intravenous vancomycin usage was allergy (61%), methicillin-resistant staphylococcus aureus colonization (17%), both allergy and colonization (14%), and other (8%). 50.4% of patients began infusion >30 minutes preoperatively (group A), and 49.6% began infusion <30 minutes preoperatively (group B). Group B had significantly higher rates of readmissions for infectious causes (3.6 vs 1.3%, P = .017). This included a statistically significant increase in confirmed prosthetic joint infections (2.2% vs 0.6%, P = .023). Regression analysis confirmed <30 minutes of vancomycin infusion as an independent risk factor for PJI when controlling for comorbidities (OR 5.22, P = .012).

CONCLUSION

Late infusion of vancomycin is common and associated with increased rates of infectious causes for readmission and PJI. Preoperative protocols should be created to ensure appropriate vancomycin administration when indicated.

Are operating room distractions, interruptions and disruptions associated with performance and patient safety? A systematic review and meta-analysis

OBJECTIVE

The operating room is a complex environment in which distractions, interruptions and disruptions (DIDs) are frequent. Our aim was to synthesize research on the relationships between DIDs and (i) operative duration, (ii) team performance, (iii) individual performance and (iv) patient safety outcomes in order to better understand how interventions can be designed to mitigate the negative effects of DIDs.

METHODS

Electronic databases (MEDLINE, Embase, CINAHL and PsycINFO) and reference lists were systematically searched. Included studies were required to report the quantitative outcomes of the association between DIDs and team performance, individual performance and patient safety. Two reviewers independently screened articles for inclusion, assessed study quality and extracted data. A random-effects meta-analysis was performed on a subset of studies reporting total operative time and DIDs.

RESULTS

Twenty-seven studies were identified. The majority were prospective observational studies (n = 15) of moderate quality. DIDs were often defined, measured and interpreted differently in studies. DIDs were significantly associated with extended operative duration (n = 8), impaired team performance (n = 6), self-reported errors by colleagues (n = 1), surgical errors (n = 1), increased risk and incidence of surgical site infection (n = 4) and fewer patient safety checks (n = 1). A random-effects meta-analysis showed that the proportion of total operative time due to DIDs was 22.0% (95% confidence interval 15.7-29.9).

CONCLUSION

DIDs in surgery are associated with a range of negative outcomes. However, significant knowledge gaps exist about the mechanisms that underlie these relationships, as well as the potential clinical and non-clinical benefits that DIDs may deliver. Available evidence indicates that interventions to reduce the negative effects of DIDs are warranted, but current evidence is not sufficient to make recommendations about potentially useful interventions.

Is radiological psoas muscle area measurement a predictor of postoperative complications after rectal resection for rectal cancer? A retrospective study

PURPOSE

Previous studies have reported that sarcopenia increases the risk of postoperative complications following colorectal resection. This retrospective study assessed the postoperative complications of rectal resection associated with sarcopenia.

METHODS

We retrospectively analyzed 262 patients who underwent curative low anterior resection for primary rectal cancer from January 2008 to May 2020 at our institution. The patients were divided into a sarcopenia group (normalized total psoas muscle area < 6.36 cm²/m² in males and < 3.92 cm²/m² in females; N = 49) and a non-sarcopenia group (N = 213).

RESULTS

The overall rate of postoperative complications within 30 days of surgery was higher in the sarcopenia group than in the non-sarcopenia group (46.9 vs. 29.6%; P = 0.028). The rate of postoperative remote infections was higher in the sarcopenia group than in the non-sarcopenia group (12.2 vs. 2.8%; P = 0.012). Sarcopenia was found to be a predictor of remote infection by a multivariate analysis (odds ratio, 4.08; 95% confidence interval, 1.12-14.80; P = 0.033).

CONCLUSION

Sarcopenia diagnosed using the psoas muscle index was found to be an independent predictive factor for postoperative remote infection after curative low anterior resection for rectal cancer.

Association of β-Lactam Allergy Documentation and Prophylactic Antibiotic Use in Surgery: A National Cross-Sectional Study of Hospitalized Patients

Alternative antibiotics for surgical prophylaxis are associated with increased adverse events and surgical site infection compared to cefazolin. In a sample of perioperative inpatients from 100 hospitals in the United States, cefazolin was 9-fold less likely to be used in patients with a documented β-lactam allergy whereas clindamycin was 45-fold more likely.

Timing of Preoperative Surgical Antibiotic Prophylaxis After Primary One-Level to Three-Level Lumbar Fusion

OBJECTIVE

The purpose of this study was to examine the relationship between timing of preoperative surgical antibiotic prophylaxis and postoperative surgical site infections (SSIs) among patients with 1-level to 3-level lumbar fusion.

METHODS

Patients having undergone a primary 1-level to 3-level lumbar fusion at a single institution were allocated into 5 groups based on the time from preoperative antibiotic administration to incision (group A, 0-15 minutes; group B, 16-30 minutes; group C, 31-45 minutes; group D, 46-60 minutes; and group E, 61+ minutes). Timing of antibiotic administration as a continuous variable was also analyzed. All patients received irrigation with 3 L of normal saline containing bacitracin as well as local administration of vancomycin powder. SSIs were identified by the definition set forth by the 2017 Centers for Disease Control and Prevention guidelines.

RESULTS

Among 1131 patients, 27 (2.4%) were found to have an SSI. Compared with patients with antibiotic administration within 0-15 minutes before incision, patients with administration 61+ minutes before incision (group 4) had significantly higher odds of developing an SSI (P < 0.001). Patients had a 1.05-fold higher likelihood of infection for each additional minute delay of administration before incision (P < 0.001). Receiver operating characteristic analysis reported an area under the curve of 0.733 and 0.776 for time as a continuous and categorical variable, respectively. Age (P = 0.02), body mass index (P = 0.03), diabetes mellitus diagnosis (P = 0.04), and type of antibiotic (P = 0.004) were significant predictors of SSI.

CONCLUSIONS

Our results show that preoperative antibiotic administration beyond 1 hour in patients who have undergone lumbar fusion is associated with higher rates of SSI.

Comparison of closed incision negative pressure wound therapy with conventional dressing for reducing wound complications in emergency laparotomy

OBJECTIVE

The aim of this study was to compare the post-operative effects of closed incision negative pressure wound therapy with conventional dressing in emergency laparotomy.

METHODS

This study was conducted from 1st November 2018 to 31st March 2020 in ABVIMS &amp; Dr. R.M.L. Hospital, New Delhi. The potential candidates for the study were patients of 18 years and above who were admitted in surgical emergency and underwent emergency laparotomy by a midline incision. Fifty random patients were alternatively allotted to group A (25 patients) and group B (25 patients). In the patients of group A, closed incision negative pressure wound therapy (ciNPWT) was applied on midline closed wound after an exploratory laparotomy procedure. The patients in group B, standard dry gauze dressing was done.

RESULTS

The mean age of patients in group A and group B were 46.76±12.20 and 41.96±8.33 years, respectively (p-value-0.11). The wound infection was present in 12% of cases in group A and 32% in group B, but when we calculate the p-value, it was found to be statistically non-significant (p-value-0.08). Similarly, seroma formation and wound dehiscence were found less in group A as compared to group B but not reached up to a statistically significant limit (p-value 0.55 and 0.38 respectively). The frequency of dressing change was 1-2 per week in 92% of cases in group A while it was 3-4 per week in 68% of cases in group B. The mean time of the frequency of dressing change was 1.24±0.72 per week and 4.28±1.90 per week in both the groups respectively (p-value &lt;0.001). There was no significant (p&gt;0.05) difference in the duration of hospital stay between group A (mean hospital stay 8.20±2.34 days) and group B (mean hospital stay 8.21±3.37 days).

CONCLUSION

Closed incision negative pressure wound therapy has no advantages over conventional dressing in terms of post-operative complications and hospital stay. However, it reduces the frequency of dressing change significantly, which reduces the mental stress of the patient and the burden of changing daily dressing.

Single-use negative pressure wound therapy reduces costs in closed surgical incisions: UK and US economic evaluation

OBJECTIVE

Single-use negative pressure wound therapy (sNPWT) following closed surgical incisions has a demonstrable effect in reducing surgical site complications (SSC). However, there is little health economic evidence to support its widespread use. We sought to evaluate the cost-effectiveness of sNPWT compared with standard care in reducing SSCs following closed surgical incisions.

METHOD

A decision analytic model was developed to explore the total costs and health outcomes associated with the use of the interventions in patients following vascular, colorectal, cardiothoracic, orthopaedic, C-section and breast surgery from the UK National Health Service (NHS) and US payer perspective over a 12-week time horizon. We modelled complications avoided (surgical site infection (SSI) and dehiscence) using data from a recently published meta-analysis. Cost data were sourced from published literature, NHS reference costs and Centers for Medicare and Medicaid Services. We conducted subgroup analysis of patients with diabetes, an American Society of Anesthesiologists (ASA) score ≥3 and body mass index (BMI) ≥30kg/m². A sensitivity analysis was also conducted.

RESULTS

sNPWT resulted in better clinical outcomes and overall savings of £105 per patient from the UK perspective and $637 per patient from the US perspective. There were more savings when higher-risk patients with diabetes, or a BMI ≥30kg/m² or an ASA≥3 were considered. We conducted both one-way and probabilistic sensitivity analysis, and the results suggested that this conclusion is robust.

CONCLUSION

Our findings suggest that the use of sNPWT following closed surgical incisions saves cost when compared with standard care because of reduced incidence of SSC. Patients at higher risk should be targeted first as they benefit more from sNPWT. This analysis is underpinned by strong and robust clinical evidence from both randomised and observational studies.

Assessment of the surgical site infection in colon surgery and antibiotic prophylaxis adequacy: A multi-center incidence study

INTRODUCTION

Surgically site infections (SSIs) are a major problem that limits the benefits of surgical interventions. The cumulative incidence of SSIs in colon surgery and compliance with antibiotic prophylaxis as well as the causes of non-compliance were evaluated.

METHODS

Multi-centre prospective surveillance study between 2012 and 2019 in seven hospitals of the Canary Health Service using an active epidemiological surveillance system. SSIs was defined according to the criteria of the Centers for Disease Control and Prevention.

RESULTS

In 2019, the cumulative incidence of SSIs was 10.6% (n=80), which implies maintaining the downward trend since 2012. The appearance of SSIs was more frequent during admission (76%). Surgical prophylaxis was adequate in 81.2%, the main causes of inadequacy being the excessive duration of the antimicrobial prescription (49%) and failure in the indication (33%). The incidence was higher in the group of organ-space infections (53.75% of the total) compared to superficial and deep infections.

CONCLUSION

The cumulative incidence of SSIs obtained is similar to that calculated in other studies carried out under similar conditions. Preoperative chemoprophylaxis was adequate in most of the interventions.

Association of Disposable Perioperative Jackets With Surgical Site Infections in a Large Multicenter Health Care Organization

Importance

To help prevent surgical site infections (SSIs), recommendations by a national organization led to implementation of a mandatory operating room policy in a large multicenter health care organization of required use of disposable perioperative jackets.

Objective

To assess whether the use of perioperative disposable jackets is associated with the incidence of SSIs.

Design, Setting, and Participants

Surgical site infection data for patients undergoing clean surgical procedures were retrospectively reviewed from 12 hospitals in a large multicenter health care organization during a 55-month period from January 1, 2014, to July 31, 2018. The incidence of SSI was analyzed for all National Healthcare Safety Network monitored and reported procedures. The patient population was split into 2 groups; the preintervention group consisted of 29 098 patients within the 26 months before the policy starting March 1, 2016, and the postintervention group consisted of 30 911 patients within 26 months after the policy.

Main Outcome and Measures

Comparison of the incidence of SSIs before and after intervention periods underwent statistical analysis. The total number of disposable jackets purchased and total expenditures were also calculated.

Exposures

Implementation of the mandated perioperative attire policy.

Results

A total of 60 009 patients (mean [SD] age, 62.8 [13.9] years; 32 139 [53.6%] male) were included in the study. The overall SSI incidence for clean wounds was 0.87% before policy implementation and 0.83% after policy implementation, which was not found to be significant (odds ratio [OR], 0.96; 95% CI, 0.80-1.14; P = .61). After accounting for possible confounding variables, a multivariable analysis demonstrated no significant reduction in SSIs (OR, 0.85; 95% CI, 0.71-1.01; P = .07). During the postintervention study period (26 months), a total of 2 010 040 jackets were purchased, which amounted to a cost of $1 709 898.46.

Conclusions and Relevance

The results of this study suggest that the use of perioperative disposable jackets is not associated with reductions in SSI for clean wounds in a large multicenter health care organization and presents a fiscal burden.

IMPPACT (Intravenous Monotherapy for Postoperative Perforated Appendicitis in Children Trial): Randomized Clinical Trial of Monotherapy Versus Multi-drug Antibiotic Therapy

BACKGROUND

Perforated appendicitis is the most common cause of intraabdominal abscess (IAA) in children. The optimal postoperative antibiotic regimen to reduce IAA has evolved in the last decade from triple-drug to 2-drug therapy (CM). Recent retrospective studies show decreased infectious complications with monotherapy PT. To date prospective comparative data are lacking. Therefore, a prospective randomized trial comparing PT versus CM was conducted.

METHODS

A multi-institutional prospective randomized trial was performed in children with perforated appendicitis comparing postoperative antibiotic regimens PT or CM. The primary outcome was 30-day postoperative IAA formation. Perforation was strictly defined as a hole in the appendix or fecalith in the abdomen, documented with intraoperative photographs.

RESULTS

One hundred sixty-two patients were enrolled during the study period. No differences in age, weight, or duration of presenting symptoms were identified. In addition, length of stay, duration of intravenous antibiotic treatment, discharge oral antibiotic treatment, and antibiotic-related complications did not differ between groups. Compared to the CM group, the PT group had significantly lower IAA rate [6.1% vs 23.8%, odd ratio (OR) 4.80, P = 0.002], lower postoperative computed tomography imaging rate (13.9% vs 29.3%, OR 2.57, P = 0.030), and fewer emergency room visits (8.8% vs 26.4%, OR 3.73, P = 0.022). Multivariate logistic regression analysis found the use of CM versus PT (OR 9.21, P = 0.021) to be the most significant predictor for developing IAA.

CONCLUSIONS

In children with perforated appendicitis, postoperative monotherapy with PT is superior to standard 2-drug therapy with CM and does not increase antibiotic-related complications or antibiotic exposure duration.

Superiority trial comparing intraoperative wound irrigation with aqueous 10% povidone-iodine to saline for the purpose of reducing surgical site infection after elective gastrointestinal surgery: study protocol for a randomised controlled trial

INTRODUCTION

Surgical site infection (SSI) is one of the most common complications after gastrointestinal surgery, with a reported incidence of approximately 10%-25%, which is higher than the rates after other types of surgery. Intraoperative wound irrigation (IOWI) is a simple intervention for SSI prevention, and recent studies have reported that IOWI with aqueous povidone-iodine (PVP-I) is significantly more effective at reducing the incidence of SSI than saline. However, the evidence level of previous trials evaluating the efficacy of aqueous PVP-I solution for preventing SSI has been low.

METHODS AND ANALYSES

We propose a single-institute, prospective, randomised, blinded-endpoint trial to assess the superiority of IOWI with aqueous 10% PVP-I solution compared with normal saline for reducing SSI in clean-contaminated wounds after elective gastrointestinal surgery. In the study group, IOWI with 40 mL of aqueous 10% PVP-I solution is performed for 1 min before skin suture, and in the control group, IOWI with 100 mL of saline is performed for 1 min before skin suture. We hypothesise that IOWI with aqueous 10% PVP-I solution will achieve a 50% reduction in the incidence of SSIs. The target number of cases is set at 950. The primary outcome is the incidence of incisional SSI up to postoperative day 30 and will be analysed in the modified intention-to-treat set.

ETHICS AND DISSEMINATION

This trial was designed and is being conducted by Saitama Medical Center, Jichi Medical University, with approval from the Bioethics Committee for Clinical Research, Saitama Medical Center, Jichi Medical University. Participant recruitment began in June 2019. The final results will be reported in international peer-reviewed journals immediately after trial completion.

TRIAL REGISTRATION NUMBER

UMIN000036889.

Comparison of cerebral AVMs in patients undergoing surgical resection with and without prior endovascular embolization

AIM

Brain arteriovenous malformations (AVMs) are congenital anomalies that present as intracranial hemorrhage or epilepsy. AVMs often remain clinically silent for extended periods. Although AVM treatment methods are controversial, three treatment strategies are usually combined or applied alone: surgical removal, embolization and stereotactic radiosurgery. We compared clinical and radiological outcomes in intracranial AVM patients treated via surgical resection with and without prior embolization.

MATERIALS AND METHODS

Patients who did (30 patients) and did not (30 patients) undergo endovascular embolization before surgical resection at the İzmir Katip Çelebi University Atatürk Training and Research Hospital Neurosurgery Clinic from 2011 to 2019 were included in this retrospective, cohort study. Symptoms at diagnosis, comorbidities and clinical (AVM and Spetzler-Martin grade) and morphological characteristics were assessed.

RESULTS

A mean one-year follow-up assessed outcomes using the modified Rankin score, and imaging studies assessed AVM obliteration post-procedure. Mean operation times for surgical resection with and without embolization were 166.50 ± 32.02 and 204.47 ± 26.66 min, respectively. Mean patient hospitalization periods for surgical resection with and without embolization were 8.43 ± 3.60 and 12.00 ± 5.51 days, respectively.

CONCLUSION

Among patients who underwent surgical resection, significant operation time and hospitalization time differences were observed in favor of patients who underwent embolization, indicating that preoperative embolization is a safe and beneficial method for treating ruptured and non-ruptured AVMs.

Prolonged antibiotic prophylaxis use in elective orthopaedic surgery - a cross-sectional analysis

Purpose

Surgical antibiotic prophylaxis (SAP) prevents surgical site infections (SSI). In orthopaedic surgery, the use of prolonged SAP (PSAP) has been reported in daily routine, despite guidelines advising against it. Therefore, we asked: What is the proportion of PSAP use, defined as administration of SAP ≥24 h after elective orthopaedic surgery? Are there patient- and surgery-related predictors of PSAP use?

Methods

This cross-sectional analysis investigated 1292 patients who underwent elective orthopaedic surgery including total joint arthroplasties at one Swiss centre between 2015 and 2017. Patient comorbidities, surgical characteristics and occurrence of SSI at 90 days in PSAP group were compared to the SAP group (< 24 h post-operative).

Results

PSAP use was 12% (155 of 1292). Patient-related factors associated with PSAP compared to the SAP group included older age (63 vs. 58y; p < 0.001), higher BMI (29 vs. 27 kg/m²; p < 0.001), ASA classification ≥3 (31% vs. 17%; p < 0.001) and lung disease (17% vs. 9%; p = 0.002). Surgery-related factors associated with PSAP were use of prosthetics (62% vs. 45%; p < 0.001), surgery of the knee (65% vs. 25%; p < 0.001), longer surgery duration (87 vs. 68 min; p < 0.001) and presence of drains (90% vs. 65%; p < 0.001). All four SSI occurred in the SAP group (0 vs. 4; p = 1.0). Surgeons administered PSAP with varying frequencies; proportions ranged from 0 to 33%.

Conclusion

PSAP use and SSI proportions were lower than reported in the literature. Several patient- and surgery-related factors associated with PSAP use were identified and some were potentially modifiable. Also, experienced surgeons seemed to implement differing approaches regarding the duration of SAP administration.

Review of calcium-sulphate-based ceramics and synthetic bone substitutes used for antibiotic delivery in PJI and osteomyelitis treatment

Infection in orthopaedic and trauma surgery remains a destructive complication with particularly challenging diagnosis and treatment due to bacterial antibiotic resistance and biofilm formation.

Along with surgical debridement and systemic antibiotics, an important type of adjuvant therapy is local antibiotic delivery, with the purpose of eliminating bacterial colonization and biofilm development.

Calcium sulphate, as a synthetic absorbable biomaterial used for local antibiotic delivery, has experienced an increasing popularity during the last decade, with multiple promoted advantages such as predictable antibiotic elution kinetics, complete and quick biodegradation, good biocompatibility, and limited associated complications.

A series of commercially available antibiotic-delivery systems based on calcium sulphate are under investigation and in clinical use, with different presentations, compositions, and application techniques.

The current article presents the main available calcium-sulphate-based products and the existing data about the clinical and preclinical research results, stemming from their implementation as local antibiotic carriers for surgical site and implant-associated infections treatment and prevention.

Cite this article: EFORT Open Rev 2021;6:297-304. DOI: 10.1302/2058-5241.6.200083

Enhanced PeriOperative Care and Health protection programme for the prevention of surgical site infections after elective abdominal surgery (EPO2CH): statistical analysis plan of a randomised controlled multicentre superiority trial

Background

Surgical site infections (SSI) are frequent complications after elective abdominal surgery. We designed the Enhanced PeriOperative Care and Health Protection programme (EPO₂CH) care bundle, comprising of intraoperative high fractional inspired oxygen; intraoperative goal-directed fluid therapy; active preoperative, intraoperative and postoperative warming; glucose control and treatment of hyperglycaemia (> 10 mmol L^− 1) in diabetics as well as non-diabetics; and wound irrigation before closure using an aqueous antiseptic. We hypothesise that EPO₂CH added to standard care reduces the incidence of SSI compared to standard care alone for elective abdominal surgery.

Methods

This trial is designed as an open label, pragmatic randomised controlled parallel-group multicentre superiority trial. The primary endpoint is the incidence of SSI, defined by the Centers for Disease Control and prevention, within 30 days after surgery. The incidence of SSI is assessed using the Dutch national complication register and medical chart review. Secondary endpoints include the SSI incidence within 90 days, incidence of anastomotic leakage at 30 and 90 days, the incidence of incisional hernia within 1 year, mortality within 1 year and 5 years, quality of life, health and disability, and cost-effectiveness. Primarily, an intention-to-treat analysis will be performed to estimate the relative risk using a log binomial model. If not feasible, a logistic regression will be used to estimate the odds ratio. A per-protocol analysis will also be performed. Furthermore, the attributive effect of the distinct interventions will be explored.

Discussion

The results of the EPO₂CH trial will determine if the EPO₂CH bundle is effective to prevent SSI incidence for patients undergoing elective abdominal surgery. Details of the statistical analysis are described in this Statistical Analysis Plan (SAP).

Trial registration

Registration number: Dutch Trial Register Trial NL5572. Registered on March 3, 2016.

SAP version: V1.0, January 8, 2020. This SAP has been written based on study protocol V10.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05202-y.