Does laminar flow ventilation reduce the rate of infection?

Evaluation of Surgical Site Infection Rates in Traumatic Surgical Fixation and Arthroplasty Performed in Laminar Flow Versus Non-laminar Flow Theatres During the COVID Pandemic

Introduction Laminar flow (LF) in theatres has become the standard of care in orthopaedic implant surgery. Most of the evidence for laminar flow use is based on arthroplasty surgery, with early studies showing a significant reduction in infections. We conducted a retrospective comparative study to assess surgical site infection (SSI) rates in consecutive patients undergoing surgery for trauma in LF and non-laminar flow (NLF) theatres. Methods Due to COVID-19 safety restrictions, trauma surgery was performed in non-laminar flow theatres during the pandemic. We identified consecutive patients who had trauma surgery pre- and post-pandemic from February 2019 to June 2021 to avoid selection bias. A total of 1809 patients were identified for the study, and the relevant patient details were collected through the hospital operating theatre software (Bluespier) and patient records (Welsh Clinical Portal). There were 917 in the laminar theatre group and 892 in the non-laminar theatre group. For the purpose of this study, we recorded SSI rates within the first 90 days. The two groups were statistically similar in terms of age and gender of the patients. Results Nineteen patients developed surgical site infections in non-laminar flow theatres and 25 patients in laminar flow theatres. There was no significant difference between the SSI rate in laminar flow theatres (2.72%) as compared to non-laminar flow theatres (2.13%) (p=0.399). There was no link between infections and the duration of surgery. Two patients in the laminar flow group were MRSA-positive and were excluded. Conclusion In our study, the laminar flow theatres did not show a statistically significant reduction in surgical site infections. We conclude in the practical environment of trauma theatres the theoretical advantage of laminar flow does not translate to an observable reduction of infections.

Laminar airflow ventilation systems in orthopaedic operating room do not prevent surgical site infections: a systematic review and meta-analysis

BACKGROUND

Laminar airflow (LAF) technologies minimize infectious microorganisms to enhance air quality and surgical site infections (SSIs). LAF lowers SSIs in some clinical studies but not others. This study analyzes laminar airflow ventilation's capacity to reduce orthopaedic surgery-related SSIs.

METHODS

The PRISMA-compliant keywords were utilized to conduct a search for pertinent articles in various databases including PubMed, MEDLINE, CENTRAL, Web of Sciences, and the Cochrane databases. Observational studies, including retrospective, prospective, and cohort designs, satisfy the PICOS criteria for research methodology. The assessment of quality was conducted utilizing the Robvis software, while the meta-analysis was performed using the RevMan application. The study's results were assessed based on effect sizes of odds ratio (OR) and risk ratio (RR).

RESULTS

From 2000 to 2022, 10 randomized controlled clinical trials with 10,06,587 orthopaedic surgery patients met the inclusion criteria. The primary outcomes were: (1) Risk of SSI, (2) Bacterial count in sampled air and (3) Reduction in SSIs. The overall pooled OR of all included studies was 1.70 (95% CI 1.10-2.64), and the overall pooled RR was 1.27 (95% CI 1.02-1.59) with p < 0.05. LAF is ineffective at preventing SSIs in orthopaedic procedures due to its high-risk ratio and odds ratio.

CONCLUSIONS

The present meta-analysis has determined that the implementation of LAF systems does not result in a significant reduction in the incidence of surgical site infections (SSIs), bacterial count in the air, or SSIs occurrence in orthopaedic operating rooms. Consequently, the installation of said equipment in operating rooms has been found to be both expensive and inefficient.

Better Operating Room Ventilation as Determined by a Novel Ventilation Index is Associated With Lower Rates of Surgical Site Infections

OBJECTIVE

The aim was to assess the impact of operating room (OR) ventilation quality on surgical site infections (SSIs) using a novel ventilation index.

BACKGROUND

Previous studies compared laminar air flow with conventional ventilation, thereby ignoring many parameters that influence air flow properties.

METHODS

In this cohort study, we surveyed hospitals participating in the Swiss SSI surveillance and calculated a ventilation index for their ORs, with higher values reflecting less turbulent air displacement. For procedures captured between January 2017 and December 2019, we studied the association between ventilation index and SSI rates using linear regression (hospital-level analysis) and with the individual SSI risk using generalized linear mixed-effects models (patient-level analysis).

RESULTS

We included 47 hospitals (182 ORs). Among the 163,740 included procedures, 6791 SSIs were identified. In hospital-level analyses, a 5-unit increase in the ventilation index was associated with lower SSI rates for knee and hip arthroplasty (-0.41 infections per 100 procedures, 95% confidence interval: -0.69 to -0.13), cardiac (-0.89, -1.91 to 0.12), and spine surgeries (-1.15, -2.56 to 0.26). Similarly, patient-level analyses showed a lower SSI risk with each 5-unit increase in ventilation index (adjusted odds ratio 0.71, confidence interval: 0.58-0.87 for knee and hip; 0.72, 0.49-1.06 for spine; 0.82, 0.69-0.98 for cardiac surgery). Higher index values were mainly associated with a lower risk for superficial and deep incisional SSIs.

CONCLUSIONS

Better ventilation properties, assessed with our ventilation index, are associated with lower rates of superficial and deep incisional SSIs in orthopedic and cardiac procedures. OR ventilation quality appeared to be less relevant for other surgery types.

Prevention of Surgical Site Infections in Neonates and Children: Non-Pharmacological Measures of Prevention

A surgical site infection (SSI) is an infection that occurs in the incision created by an invasive surgical procedure. Although most infections are treatable with antibiotics, SSIs remain a significant cause of morbidity and mortality after surgery and have a significant economic impact on health systems. Preventive measures are essential to decrease the incidence of SSIs and antibiotic abuse, but data in the literature regarding risk factors for SSIs in the pediatric age group are scarce, and current guidelines for the prevention of the risk of developing SSIs are mainly focused on the adult population. This document describes the current knowledge on risk factors for SSIs in neonates and children undergoing surgery and has the purpose of providing guidance to health care professionals for the prevention of SSIs in this population. Our aim is to consider the possible non-pharmacological measures that can be adopted to prevent SSIs. To our knowledge, this is the first study to provide recommendations based on a careful review of the available scientific evidence for the non-pharmacological prevention of SSIs in neonates and children. The specific scenarios developed are intended to guide the healthcare professional in practice to ensure standardized management of the neonatal and pediatric patients, decrease the incidence of SSIs and reduce antibiotic abuse.

Reducing Implant Infection in Orthopaedics (RIIiO): Results of a pilot study comparing the influence of forced air and resistive fabric warming technologies on postoperative infections following orthopaedic implant surgery

BACKGROUND

Active warming during surgery prevents perioperative hypothermia but the effectiveness and postoperative infection rates may differ between warming technologies.

AIM

To establish the recruitment and data management strategies needed for a full trial comparing postoperative infection rates associated with forced air warming (FAW) versus resistive fabric warming (RFW) in patients aged >65 years undergoing hemiarthroplasty following fractured neck of femur.

METHODS

Participants were randomized 1:1 in permuted blocks to FAW or RFW. Hypothermia was defined as a temperature of <36°C at the end of surgery. Primary outcomes were the number of participants recruited and the number with definitive deep surgical site infections.

FINDINGS

A total of 515 participants were randomized at six sites over a period of 18 months. Follow-up was completed for 70.1%. Thirty-seven participants were hypothermic (7.5% in the FAW group; 9.7% in the RFW group). The mean temperatures before anaesthesia and at the end of surgery were similar. For the primary clinical outcome, there were four deep surgical site infections in the FAW group and three in the RFW group. All participants who developed a postoperative infection had antibiotic prophylaxis, a cemented prosthesis, and were operated under laminar airflow; none was hypothermic. There were no serious adverse events related to warming.

CONCLUSION

Surgical site infections were identified in both groups. Progression from the pilot to the full trial is possible but will need to take account of the high attrition rate.

Laminar Air Flow Handling Systems in the Operating Room

BACKGROUND

Surgical site infection is associated with a substantial healthcare burden and remains one of the most challenging complications to treat. Airborne particles carrying contaminating micro-organisms are responsible for the majority of these infections.

METHODS

Various operating theater ventilatory systems have been developed to prevent direct airborne bacterial inoculation of the surgical wound. Laminar air flow uses positive pressure air currents through filtration units to direct air streams away from the operative field in order to create an ultraclean zone around the operative site.

DISCUSSION

Early studies reported lower infection rates with laminar air flow and therefore it became the accepted standard for implant-related surgery. However, more recent evidence has questioned its clinical importance. The purpose of this article is to review contemporary laminar air flow handling systems and the current evidence behind their use.

Forced-Air Warming and Resistive Heating Devices. Updated Perspectives on Safety and Surgical Site Infections

Introduction: Perioperative hypothermia is one of the most common phenomena seen among surgical patients, leading to numerous adverse outcomes such as intraoperative blood loss, cardiac events, coagulopathy, increased hospital stay and associated costs. Forced air warming (FAW) and resistive heating (RH) are the two most commonly used and widely studied devices to prevent perioperative hypothermia. The effect of FAW on operating room laminar flow and surgical site infection is unclear and we initiated an extensive literature search in order to get a scientific insight of this aspect.

Material and Methods: The literature search was conducted using the Medline search engine, PubMed, Cochrane review, google scholar, and OSU library.

Results: Out of 92 Articles considered initially for review we selected a total of 73 relevant references. Currently there is no robust evidence to support that FAW can increase SSIs. In addition, both of the two warming devices present safety problems.

Conclusion: As unbiased independent reviewers, we advise clinicians to weigh the risks and benefits when using either one of these devices; no change in the current practice is necessary until further data emerges.

The effectiveness of ultra-clean air operating theatres in the prevention of deep infection in joint arthroplasty surgery

Deep infection was identified as a serious complication in the earliest days of total hip arthroplasty. It was identified that airborne contamination in conventional operating theatres was the major contributing factor. As progress was made in improving the engineering of operating theatres, airborne contamination was reduced. Detailed studies were carried out relating airborne contamination to deep infection rates.

In a trial conducted by the United Kingdom Medical Research Council (MRC), it was found that the use of ultra-clean air (UCA) operating theatres was associated with a significant reduction in deep infection rates. Deep infection rates were further reduced by the use of a body exhaust system. The MRC trial also included a detailed microbiology study, which confirmed the relationship between airborne contamination and deep infection rates.

Recent observational evidence from joint registries has shown that in contemporary practice, infection rates remain a problem, and may be getting worse. Registry observations have also called into question the value of “laminar flow” operating theatres.

Observational evidence from joint registries provides very limited evidence on the efficacy of UCA operating theatres. Although there have been some changes in surgical practice in recent years, the conclusions of the MRC trial remain valid, and the use of UCA is essential in preventing deep infection.

There is evidence that if UCA operating theatres are not used correctly, they may have poor microbiological performance. Current UCA operating theatres have limitations, and further research is required to update them and improve their microbiological performance in contemporary practice.

Cite this article: Bone Joint J 2018;100-B:1264–9.

Hip fracture surgery in mixed-use emergency theatres: is the infection risk increased? A retrospective matched cohort study

Introduction The National Institute of Health and Care Excellence recommends that people with hip fracture should have surgery on the day of, or the day after, admission. However, there remains unacceptable variation in performance around the country, with a range of 13-91% of patients meeting this target. Dedicated trauma lists have insufficient capacity in many hospitals. We occasionally employ a mixed-use emergency theatre to facilitate early surgery. Increased risk of infection has been raised as a concern owing to microbial surface contamination from a preceding unclean case and lack of laminar flow in these theatres. The objective of this study was to investigate whether there is an increased risk of surgical site infections in patients who had hip fracture surgery in a mixed-use emergency theatre. Methods Between August 2010 and July 2014, 74 patients had hip fracture surgery in a mixed-use emergency theatre without laminar flow. This group was compared with a control group of patients who had hip fracture surgery in dedicated orthopaedic theatres with laminar flow. Infection was the primary outcome measured. Results There was no statistically significant difference in the rate of infection, length of stay or 30-day mortality, readmission or reoperation rates between the two groups. Conclusions Operating on hip fractures in mixed-use theatre did not lead to an increase in infection or other complications in our series. We feel that the risk of infection can be balanced against advantages of timely operation and it may therefore be justified to use these theatres when faced with lack of time on the trauma list. A much larger series would be required to investigate the effects of confounders.

Primary hip and knee arthroplasty in a temporary operating theatre is associated with a significant increase in deep periprosthetic infection

Aims

Infection following total hip or knee arthroplasty is a serious complication. We noted an increase in post-operative infection in cases carried out in temporary operating theatres. We therefore compared those cases performed in standard and temporary operating theatres and examined the deep periprosthetic infection rates.

Patients and methods

A total of 1223 primary hip and knee arthroplasties were performed between August 2012 and June 2013. A total of 539 (44%) were performed in temporary theatres. The two groups were matched for age, gender, body mass index and American Society of Anesthesiologists grade.

Results

The deep infection rate for standard operating theatres was 0 of 684 (0%); for temporary theatres it was eight of 539 (1.5%) (p = 0.001).

Conclusion

Use of a temporary operating theatre for primary hip and knee arthroplasty was associated with an unacceptable increase in deep infection. We do not advocate the use of these theatres for primary joint arthroplasty. Cite this article: Bone Joint J 2017;99-B:917–20.