Laminar Air Flow Handling Systems in the Operating Room

Operating Room Air May Harbor Pathogens: The Role of an Ultraviolet Air Filtration Unit

BACKGROUND

One important factor for the prevention of surgical site infections is ultraclean air in the operating room (OR). Still, the direct sterilization potential of most technologies, especially in a dynamic clinical setting, is not well understood. We aimed to determine and compare the microbial presence from the inlet and outlet flow of a filtration unit with crystalline ultraviolet-C (C-UVC) light.

METHODS

A prospective study was conducted at a single institution, where primary total joint arthroplasty and spine surgeries were performed. The OR was fitted with a positive ventilation system. In addition, a filtration unit with a C-UVC sterilizing light was placed in the OR. The inlet and outlet air flows were swabbed simultaneously and compared. Swabs were processed for culture and next-generation sequencing.

RESULTS

The mean length of the surgical procedures sampled was 68 ± 13 minutes. Overall, 19 out of 200 (9.5%) swabs isolated microorganisms. Inlet air swabs were positive at a higher rate (16 versus 3%; P < .01) compared to the outlet air swabs. A wide variety of Gram-positive, Gram-negative, and anaerobic bacteria were isolated, but fungi were only recovered from inlet air swabs. The detection of microorganisms was also higher when more door openings were performed (32.5 ± 7.1 versus 27.9 ± 5.6; P < .01).

CONCLUSIONS

Air swabs mainly isolated microorganisms from the inlet flow to the filtration unit with a C-UVC light. The sterilizing unit counteracted factors affecting the air quality in the OR, namely door openings, surgical personnel, and tissue combustion.

Prosthetic joint infections of the shoulder: A review of the recent literature

Introduction

Shoulder arthroplasty is a common treatment for shoulder arthritis. Prosthetic joint infection of the shoulder (PJIS) is a debilitating complication to the patient and the healthcare system. Incidence of infection is 0.98-5% for primary arthroplasty. The mean hospital cost for two-stage revision was approximately $35,824. The aim of this paper is to review the recent literature and collate the latest evidence to aid diagnosis and treatment of this serious complication.

Methods

A literature review was performed using PubMed and Google Scholar databases. A search strategy was adopted using the keywords: 'infection' AND 'shoulder arthroplasty' OR 'total shoulder arthroplasty'OR 'TSA' OR 'reverse shoulder arthroplasty' OR 'RSA' OR 'rTSA'. This initial search resulted in 349 articles. A PRISMA flowchart process was followed. Duplicates were removed, screening was performed and the resulting full texts were analysed and further excluded, leaving 46 articles suitable for inclusion. A PICO search strategy was also used.

Results and interpretation

Risk factors for PJIS include procedure type, trauma indications and patient factors.The organism commonly isolated is Cutebacterium acnes, which makes diagnosis challenging due to its indolent nature. Investigations include biochemical tests, synovial aspirate, tissue cultures and radiological examinations.Treatment depends on the depth of the infection and the patient requirements. Medical treatment with antibiotics to local debridement, cement spacer and revision arthroplasty have all been described in the literature. A multidisciplinary decision is made on the microbiological evidence and patient factors.

Conclusion

PJIS is a rare but potentially devastating complication of shoulder arthroplasty and diagnosis is often challenging. There has been much research performed recently, providing more evidence on how to optimise management.

Melimine-Modified 3D-Printed Polycaprolactone Scaffolds for the Prevention of Biofilm-Related Biomaterial Infections

Biomaterial-associated infections are one of the major causes of implant failure. These infections result from persistent bacteria that have adhered to the biomaterial surface before, during, or after surgery and have formed a biofilm on the implant's surface. It is estimated that 4 to 10% of implant surfaces are contaminated with bacteria; however, the infection rate can be as high as 30% in intensive care units in developed countries and as high as 45% in developing countries. To date, there is no clinical solution to prevent implant infection without relying on the use of high doses of antibiotics supplied systemically and/or removal of the infected device. In this study, melimine, a chimeric cationic peptide that has been tested in Phase I and II human clinical trials, was immobilized onto the surface of 3D-printed medical-grade polycaprolactone (mPCL) scaffolds via covalent binding and adsorption. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra of melimine-treated surfaces confirmed immobilization of the peptide, as well as its homogeneous distribution throughout the scaffold surface. Amino acid analysis showed that melimine covalent and noncovalent immobilization resulted in a peptide density of ∼156 and ∼533 ng/cm², respectively. Furthermore, we demonstrated that the immobilization of melimine on mPCL scaffolds by 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride (EDC) coupling and noncovalent interactions resulted in a reduction of Staphylococcus aureus colonization by 78.7% and 76.0%, respectively, in comparison with the nonmodified control specimens. Particularly, the modified surfaces maintained their antibacterial properties for 3 days, which resulted in the inhibition of biofilm formation in vitro. This system offers a biomaterial strategy to effectively prevent biofilm-related infections on implant surfaces without relying on the use of prophylactic antibiotic treatment.

Moving towards green anaesthesia: Are patient safety and environmentally friendly practices compatible? A focus on single-use devices

OBJECTIVE

Discuss if the use of disposable or reusable medical devices leads to a difference in terms of hospital-acquired infection or bacterial contamination. Determine which solution is less expensive and has less environmental impact in terms of carbon footprint, energy and water consumption and amount of waste.

METHODS

We carried out a narrative review. Articles published in English and French from January 2000 to April 2020 were identified from PubMed.

RESULTS

We retrieved 81 articles, including 12 randomised controlled trial, 21 literature reviews, 13 descriptive studies, 6 experimental studies, 9 life-cycle studies, 6 cohort studies, 2 meta-analysis, 4 case reports and 8 other studies. It appears that pathogen transmission in the anaesthesia work area is mainly due to the lack of hand hygiene among the anaesthesia team. The benefit of single-use devices on infectious risk is based on weak scientific arguments, while reusable devices have benefits in terms of costs, water consumption, energy consumption, waste, and reducing greenhouse gas emissions.

CONCLUSION

Disposable medical devices and attire in the operating theatre do not mitigate the infectious risk to the patients but have a greater environmental, financial and social impact than the reusable ones. This study is the first step towards recommendations for more environmental-friendly practices in the operating theatre.

Laminar airflow decreases microbial air contamination compared with turbulent ventilated operating theatres during live total joint arthroplasty: a nationwide survey

BACKGROUND

Preventing surgical site infections and prosthetic joint infections is crucial for patient safety after total joint arthroplasty. Microbial air contamination has been suggested as a risk factor. Therefore, the ventilation system that will reduce air contamination most effectively in operating theatres (OTs) has been discussed.

AIM

To determine whether laminar airflow (LAF) ventilation is superior to turbulent airflow (TAF) ventilation by looking at the colony forming units (cfu) count during live total hip and knee arthroplasties. Furthermore, to explore whether the number of OT personnel, door and cabinet lock openings and technical parameters of the ventilation systems have an impact on the number of cfu.

METHODS

Active air sampling and passive sedimented bacterial load were performed in 17 OTs, equipped with either LAF or TAF ventilation, during 51 live surgeries while observations were noted.

FINDINGS

LAF OTs reduced cfu counts compared with TAF OTs during live surgery (P<0.001). All LAF OTs provided ultraclean air whereas TAF had nine procedures exceeding the threshold of 10 cfu/m³. Door and cabinet lock openings and number of personnel did not influence the cfu count, while it decreased with increasing volume and total air change per hour (P<0.05).

CONCLUSION

All LAF OTs had cfu counts within recommendations and provided lower cfu counts compared with TAF OTs. The number of OT personnel and total openings did not have an influence on cfu counts. Increased volume of the OT and total air change per hour showed a decrease in active cfu counts.

Prevention of infection in primary THA and TKA

Rates of peri-prosthetic joint infection (PJI) in primary total hip and total knee arthroplasty range between 0.3% and 1.9%, and up to 10% in revision cases. Significant morbidity is associated with this devastating complication, the economic burden on our healthcare system is considerable, and the personal cost to the affected patient is immeasurable.

The risk of surgical site infection (SSI) and PJI is related to surgical factors and patient factors such as age, body mass index (BMI), co-morbidities, and lifestyle. Reducing the risk of SSI in primary hip and knee arthroplasty requires a multi-faceted strategy including pre-operative patient bacterial decolonization, screening and avoidance of anaemia, peri-operative patient warming, skin antisepsis, povidone-iodine wound lavage, and anti-bacterial coated sutures.

This article also considers newer concepts such as the influence of bearing surfaces on infection risk, as well as current controversies such as the potential effects of blood transfusion, laminar flow, and protective hoods and suits, on infection risk.

Cite this article: EFORT Open Rev 2020;5:604-613. DOI: 10.1302/2058-5241.5.200004

Arthroplasty during the COVID-19 Pandemic

This article aims to give a brief outline of the pathogenesis and transmission of SARS-CoV-2 and how to safely navigate an arthroplasty practice during and after the pandemic.

Re-examining causes of surgical site infections following elective surgery in the era of asepsis

The currently accepted assumption that most surgical site infections (SSIs) occurring after elective surgery under standard methods of antisepsis are due to an intraoperative contamination event, remains unproven. We examined the available evidence in which microbial cultures of surgical wounds were taken at the conclusion of an operation and determined that such studies provide more evidence to refute that an SSI is due to intraoperative contamination than support it. We propose that alternative mechanisms of SSI development should be considered, such as when a sterile postoperative wound becomes infected by a pathogen originating from a site remote from the operative wound-eg, from the gums or intestinal tract (ie, the Trojan Horse mechanism). We offer a path forward to reduce SSI rates after elective surgery that includes undertaking genomic-based microbial tracking from the built environment (ie, the operating room and hospital bed), to the patient's own microbiome, and then to the surgical site. Finally, we posit that only by generating this dynamic microbial map can the true pathogenesis of SSIs be understood enough to inform novel preventive strategies against infection following elective surgery in the current era of asepsis.

Efficacy of an ambulance ventilation system in reducing EMS worker exposure to airborne particles from a patient cough aerosol simulator

The protection of emergency medical service (EMS) workers from airborne disease transmission is important during routine transport of patients with infectious respiratory illnesses and would be critical during a pandemic of a disease such as influenza. However, few studies have examined the effectiveness of ambulance ventilation systems at reducing EMS worker exposure to airborne particles (aerosols). In our study, a cough aerosol simulator mimicking a coughing patient with an infectious respiratory illness was placed on a patient cot in an ambulance. The concentration and dispersion of cough aerosol particles were measured for 15 min at locations corresponding to likely positions of an EMS worker treating the patient. Experiments were performed with the patient cot at an angle of 0° (horizontal), 30°, and 60°, and with the ambulance ventilation system set to 0, 5, and 12 air changes/hour (ACH). Our results showed that increasing the air change rate significantly reduced the airborne particle concentration (p < 0.001). Increasing the air change rate from 0 to 5 ACH reduced the mean aerosol concentration by 34% (SD = 19%) overall, while increasing it from 0 to 12 ACH reduced the concentration by 68% (SD = 9%). Changing the cot angle also affected the concentration (p < 0.001), but the effect was more modest, especially at 5 and 12 ACH. Contrary to our expectations, the aerosol concentrations at the different worker positions were not significantly different (p < 0.556). Flow visualization experiments showed that the ventilation system created a recirculation pattern which helped disperse the aerosol particles throughout the compartment, reducing the effectiveness of the system. Our findings indicate that the ambulance ventilation system reduced but did not eliminate worker exposure to infectious aerosol particles. Aerosol exposures were not significantly different at different locations within the compartment, including locations behind and beside the patient. Improved ventilation system designs with smoother and more unidirectional airflows could provide better worker protection.

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.