Lack of influence of body exhaust gowns on aerobic bacterial surface counts in a mixed-ventilation operating theatre. A study of 62 hip arthroplasties

Surgical gowns as a safety barrier under non-standard environmental conditions

In this prospective study, we aimed to investigate whether surgical gowns become contaminated during surgery. Samples from the gowns of five surgeons during 19 surgeries were collected using sterile swabs in circular standard delimited areas on both wrists and the mid-chest at three time-points: immediately before surgical incision (t=0), 30 min (t=30), and 60 min (t=60) later. Additionally, at t=0 and t=60, three settle plates of plate count agar were positioned at 1.5 m from the ground and remained open for 20 min. The operating room temperature and relative humidity were monitored. The swabs were cultivated and incubated, and colony-forming units per gram (CFU/g) counts were measured. The CFU/g counts for bacteria or fungi did not differ among the three sampling sites. The surgeons' lateral dominance in manual dexterity did not influence the gowns' contamination. There were significant variations in the temperature and relative humidity over time, but not in the CFU/g counts. In conclusion, during the first hour of surgery, surgical gowns did not become a source of contamination and are an effective barrier against bacterial and fungal contamination even under non-standard surgical environmental conditions.

The effect of the surgical helmet system on intraoperative contamination in arthroplasty surgery

Aims

The surgical helmet system (SHS) was developed to reduce the risk of periprosthetic joint infection (PJI), but the evidence is contradictory, with some studies suggesting an increased risk of PJI due to potential leakage through the glove-gown interface (GGI) caused by its positive pressure. We assumed that SHS and glove exchange had an impact on the leakage via GGI.

Methods

There were 404 arthroplasty simulations with fluorescent gel, in which SHS was used (H+) or not (H-), and GGI was sealed (S+) or not (S-), divided into four groups: H+S+, H+S-, H-S+, and H-S-, varying by exposure duration (15 to 60 minutes) and frequency of glove exchanges (0 to 6 times). The intensity of fluorescent leakage through GGI was quantified automatically with an image analysis software. The effect of the above factors on fluorescent leakage via GGI were compared and analyzed.

Results

The leakage intensity increased with exposure duration and frequency of glove exchanges in all groups. When SHS was used and GGI was not sealed (H+S-), the leakage intensity via GGI had the fastest increase, consistently higher than other groups (H+S+, H-S+ and H-S-) after 30 minutes (p < 0.05) and when there were more than four instances of glove exchange (p < 0.05). Additionally, the leakage was strongly correlated with the duration of exposure (rs = 0.8379; p < 0.050) and the frequency of glove exchange (rs = 0.8198; p < 0.050) in H+S-. The correlations with duration and frequency turned weak when SHS was not used (H-) or GGI was sealed off (S+).

Conclusion

Due to personal protection, SHS is recommended in arthroplasties. Meanwhile, it is strongly recommended to seal the GGI of the inner gloves and exchange the outer gloves hourly to reduce the risk of contamination from SHS.

Effect of far-infrared radiation on inhibition of colonies on packaging during storage of sterilised surgical instruments

The sterilisation of surgical instruments is a major factor in infection control in the operating room (OR). All items used in the OR must be sterile for patient safety. Therefore, the present study evaluated the effect of far-infrared radiation (FIR) on the inhibition of colonies on packaging surface during the long-term storage of sterilised surgical instruments. From September 2021 to July 2022, 68.2% of 85 packages without FIR treatment showed microbial growth after incubation at 35 °C for 30 days and at room temperature for 5 days. A total of 34 bacterial species were identified, with the number of colonies increasing over time. In total, 130 colony-forming units were observed. The main microorganisms detected were Staphylococcus spp. (35%) and Bacillus spp. (21%) , Kocuria marina and Lactobacillus spp. (14%), and mould (5%). No colonies were found in 72 packages treated with FIR in the OR. Even after sterilisation, microbial growth can occur due to movement of the packages by staff, sweeping of floors, lack of high-efficiency particulate air filtration, high humidity, and inadequate hand hygiene. Thus, safe and simple far-infrared devices that allow continuous disinfection for storage spaces, as well as temperature and humidity control, help to reduce microorganisms in the OR.

Reduction in Operating Room Airborne Particle Burden and Time-Dependent Contamination of Sterile Instrument Trays With the Use of a Novel Air Filtration System

Introduction

Postoperative infections represent a substantial burden to patients and healthcare systems. To improve patient care and reduce healthcare expenditures, interventions to reduce surgical infections must be employed. The crystalline C-band ultraviolet (UV-C) air filtration technology (Aerobiotix Inc., Miamisburg, OH, USA) has been designed to reduce airborne bioburden through high-quality filtration and germicidal irradiation. The purpose of this study was to assess the ability of a novel UV-C air filtration device to reduce airborne particle counts and contamination of surgical instrument trays in an operating room (OR) setting.

Materials and methods

Thirty sterile instrument trays were opened in a positive-air-flow OR. The trays were randomly assigned to one of two groups (UV-C or control, n=15 per group). In the UV-C group, the UV-C filtration device was used and in the control, it was not. All trays were opened with the use of a sterile technique and left exposed in the OR for four hours. Air was sampled by a particle counter to measure the numbers of 5µm and 10µm particles. Culture specimens were obtained from the trays to assess for bacterial contamination. Outcome data were collected at 30-minute intervals for the duration of the four-hour study period.

Results

Use of the UV-C device resulted in statistically significant reductions in the numbers of 5µm (average of 64.9% reduction when compared with the control, p<0.001) and 10µm (average of 65.7% reduction when compared with the control, p<0.001)-sized particles detectable in the OR. There was no significant difference in the overall rates of contamination (33.3% in the control group vs. 26.7% in the UV-C group, p=1.0) or the time to contamination (mean survival of 114 minutes in the control group vs. 105 minutes in the UV-C group, p=0.72) of surgical instrument trays with the use of the UV-C device.

Conclusions

The results demonstrate that the UV-C filtration device can successfully reduce airborne bioburden in standard ORs, suggesting that it may have the potential to reduce the risk for wound and hardware infections. Further clinical trials are necessary to better determine the effect of this air filtration system on postoperative infection rates.

The safety of a novel single-drape cover for sterile back tables in the operating room compared to the standard two-drape method: an experimental study

BACKGROUND

Covering the prepared sterile back tables (PSBTs) during periods of nonuse and during active surgeries may decrease contamination of sterile surgical instruments that have direct contact to surgical wound. The Association of periOperative Registered Nurses (AORN) declared that an easy method for covering and removing the drape will ultimately be most effective (e.g. standard two-drape method). Hence, this study was designed to test the hypothesis that using a novel single-drape cover had more efficiency and safety in decreasing airborne bacteria-carrying particles (ABCPs) settling on the PSBTs during static and dynamic periods than the standard two-drape method.

METHODS

This experimental study was conducted with using 918 agar plates to detect contamination of the PSBTs with ABCPs on two conditions (static and dynamic) at an academic medical center in Kashan, Iran, from September 25, 2021, to January 20, 2022. The contamination of PSBTs was evaluated by 6 agar settle plates (n = 918 in total) on each PSBT in static and dynamic operating room (OR) conditions. At each time-point, this set-up was repeated on two occasions else during data collection, establishing 81 PSBTs in total. Tested groups included the PSBTs covered with the standard two-drape method, the novel single-drape cover, or no cover. The plates were collected after 15, 30, 45, 60, 120, 180, 240 min and 24 h. The primary outcome measured was comparison of mean bioburden of ABCPs settling on covered PSBTs on two conditions by using agar settle plates. The secondary outcomes measured were to determine the role of covering in decreasing contamination of PSBTs and the estimation of time-dependent surgical instrument contamination in the uncovered PSBTs on two conditions by using agar settle plates.

RESULTS

Covering the PSBTs during static and dynamic OR conditions lead to a significantly decreased bioburden of ABCPs on them (P < 0.05). No differences were seen between the standard two-drape method and the novel single-drape cover (P > 0.05).

CONCLUSIONS

We found that there is no preference for using the novel single-drape cover than the standard two-drape method. Our results showed a significant decrease in bioburden of ABCPs on the PSBTs when those were covered during static and dynamic OR conditions, indicating the efficiency for covering the PSBTs during periods of nonuse and during active surgery.

Do Ultraviolet Air Disinfection Units Reduce Contamination by Particulates in Total Knee Replacement Procedures?

BACKGROUND

Prosthetic joint infections have become the leading cause of joint replacement failure. The primary sources of contamination are skin flora and bacteria from airborne particles. Portable ultraviolet air disinfection units are used in the Operating Room (OR) to prevent contamination from airborne particles; however, their effectiveness is not proven. The purpose of this study was to compare the rate of contamination of sites with and without Ultraviolet (UV) air disinfection units during active surgeries.

METHODS

Sedimentation rates of viable particles were measured during 40 primary TKA procedures. Half of the procedures were performed with ultraviolet air disinfection units. Air-borne particles were collected on nitrocellulose membranes at 5 locations within the OR. After incubation, all microbial colonies were counted and the sedimentation rates were reported in CFUs/m²/hr. 10 additional trials were performed in an empty OR with no staff present.

RESULTS

The average contamination rate of all sites was 22 ± 1.1 CFUs/m²/hr in the empty OR vs. 21.3 ± 4.6 CFUs/m²/hr with UV units and 20.3 ± 4.9 CFUs/m²/hr without (P = .03, P = .03, P = .964). Viable contaminates were found in the sterile field in 25% of UV cases vs 45% non-UV. These differences were not statistically significant. There were differences found however, according to the number of staff in the room (6 vs 7 staff: P = .036, 6 vs 8 staff: P = .004).

CONCLUSION

There was no statistical difference in contamination rate with the usage or non-usage of UV units. These 40 cases shows that the largest variables affecting the contamination rate were the number of staff present and size of the OR.

Can clothing systems and human activities in operating rooms with mixing ventilation systems help achieve 10 CFU/m3 level during orthopaedic surgeries?

The level of airborne microbial contamination in operating rooms (ORs) is an important indicator of indoor air quality and ensures a clean surgical environment. It is necessary to research how different factors affect the colony forming unit (CFU) level during surgery in a mixing ventilation (MV) operating room (OR) to fulfil an ultra-clean air requirement. The main objective of this study is to clarify the possibility of achieving the requirement for an ultraclean operating room (≤ 10 CFU/m³) with mixing ventilation from two factors of clothing and human activities. The experiment results verified that the average CFU/m³ of three of five mock-up surgeries was 8.5 which was below or equal to the ultra-clean requirement, while the other two mock-up surgeries did not meet the ultra-clean requirement. Surgical activities together with clothing level of surgical staff in ORs seem to be the most significant reason for the high CFU level during surgery. It is possible to achieve the ultraclean air requirement (≤ 10 CFU/m³) during a surgical process with proper clothing and low surgical activities in ORs. This study clarifies the effect of clothing and human activities on the CFU level in the surgical microenvironment in ORs and contributes to developing new code of products for the surgical team.

Orthopedic Surgical Helmet Systems Significantly Impair Speech Intelligibility

Surgical suits provide protection to orthopedic surgeons, but the suits and fan noise may interfere with communication between operative team members. The goal of this study was to quantify the fan sound and effect of the suit, fan, and N95 mask. Sound levels were measured using a specialized manikin and evaluated using preferred speech interference levels (PSILs), noise criterion (NC) ratings, and comparison with speech sound levels from the literature. Additionally, sound blocking due to the surgical suit was measured and combined effects of the fan and suit were described using a signal to noise ratio (SNR). The noise with the fan at medium and high speed was louder than average speech and the PSILs at these speeds were significantly higher than with the fan off. The fan NC rating of 50 to 60 exceeded the recommended range of 25 to 30 for operating rooms. The N95 mask, space suit, and distance between speaker and receiver all reduced the sound signal at the receiver's ear, with the worst case being full personal protective equipment on both and speaker distanced from receiver. The estimated SNR for the suit and fan system was negative for many frequency bands used in speech, indicating more noise than signal. Multiple measures indicated that the fan noises were at levels associated with speech interference. This noise combined with sound blocking provided by the suit produced SNRs commonly associated with noisy to very noisy environments. This study suggests the combined effects of the suit, fan, and distance may negatively impact operating room communication. [Orthopedics. 2021;44(4):208-214.].

Do Double-fan Surgical Helmet Systems Result in Less Gown-particle Contamination Than Single-fan Designs?

BACKGROUND

Surgical helmet systems commonly are stand-alone systems with a single fan blowing air into the suit, creating positive pressure that blows particles out through areas of low resistance, possibly contaminating surgical attire and the surgical field. Two-fan systems were developed more recently to release spent air, also theoretically lowering pressure in the suit and decreasing the aforementioned risk of particle contamination. To our knowledge no study to date has measured the potential differences in gown particle contamination to support this hypothesis.

QUESTIONS/PURPOSES

We compared a commonly used single-fan system versus a two-fan system and asked: (1) Which fan system results in less gown particle contamination? (2) Are there differences between the systems in the location of contamination?

METHODS

Using an existing experimental study model, two surgeons performed five 30-minute TKA simulations comparing a single-fan to a double-fan helmet system after applying fluorescent powder to the hands, axillae, and chest. Both are two-piece hood and gown systems. The single-fan sits on top of the helmet blowing air into the suit; the double-fan system has a second fan positioned at the rear blowing out spent air. Ultraviolet light-enhanced photographs were subsequently obtained of the flexor and extensor surfaces of the arms, axillary areas, and front and back of the chest. We chose these locations because they all contain either a seam or an overlap between gown and hood or gloves through which particles can escape. The images were scored for contamination on a scale of 1 (zero specks) to 4 (> 100 specks) by three independent observers. Interobserver correlation was assessed through Spearman's test yielding 0.91 (95% CI 0.86 to 0.94; p < 0.0001), 0.81 (95% CI 0.73 to 0.87; p < 0.0001) and 0.87 (95% CI 0.80 to 0.91; p < 0.0001) between observers 1 and 2, observers 1 and 3, and observers 2 and 3, rendering the used scale reliable. Results of the observers were averaged and compared using the Mann-Whitney U test.

RESULTS

There was no difference in overall gown particle contamination between the systems (overall single-fan median contamination score 2.5 of 4 [interquartile range Q1-Q3 0-3.42] versus double fan 1 out of 4 (Q1-Q3 0-3); p = 0.082), but all tests showed there was contamination at the gown-glove interface. In general, there were few differences between the two systems in terms of location of the contamination; however, when comparing only the axillary regions, we found that the single-fan group (median score 3.67 [Q1-Q3 3-4]) showed more contamination than the double-fan group (2.33 [Q1-Q3 0-3.08]); p = 0.01.

CONCLUSION

We found no difference in gown particle contamination between a single-fan and a double-fan helmet design. However, we note that contamination was present in all tests with both systems, so surgeons should not assume that these systems provide a contamination-free environment.

CLINICAL RELEVANCE

When using such helmets, the surgeon should not place items close to the axillary region because the seam of the gown may have low resistance to particle contamination. Gown designs could be improved by creating better seals, especially at the arm-body seam.

Microbiological Air Quality in Heating, Ventilation and Air Conditioning Systems of Surgical and Intensive Care Areas: The Application of a Disinfection Procedure for Dehumidification Devices

International literature data report that the increase of infectious risk may be due to heating, ventilation and air conditioning (HVAC) systems contaminated by airborne pathogens. Moreover, the presence of complex rotating dehumidification wheels (RDWs) may complicate the cleaning and disinfection procedures of the HVAC systems. We evaluated the efficacy of a disinfection strategy applied to the RDW of two hospitals’ HVAC systems. Hospitals have four RDW systems related to the surgical areas (SA1 and SA2) and to the intensive and sub-intensive care (IC and sIC) units. Microbiological air and surface analyses were performed in HVAC systems, before and after the disinfection treatment. Hydrogen peroxide (12%) with silver ions (10 mg/L) was aerosolized in all the air sampling points, located close to the RDW device. After the air disinfection procedure, reductions of total microbial counts at 22 °C and molds were achieved in SA2 and IC HVAC systems. An Aspergillus fumigatus contamination (6 CFU/500 L), detected in one air sample collected in the IC HVAC system, was eradicated after the disinfection. The surface samples proved to be of good microbiological quality. The results suggest the need for a disinfection procedure to improve the microbiological quality of the complex HVAC systems, mostly in surgical and intensive care areas.

Centers for Disease Control and Prevention 2017 Guidelines for Prevention of Surgical Site Infections: Review and Relevant Recommendations

PURPOSE OF REVIEW

The associated patient morbidity and resource-intensive nature of managing surgical site infections (SSI) has focused attention toward not only improving treatment protocols but also enhancing preventative measures. The purpose of this review was to summarize the relevant updated CDC guidelines for the prevention of SSI that were released in 2017. The CDC recommends the integration of the guidelines for improvement in quality metrics, reportable outcomes, and patient safety.

RECENT FINDINGS

The updated guidelines include generalized recommendations for parenteral antimicrobial prophylaxis, non-parenteral antimicrobial prophylaxis, glycemic control, normothermia, oxygenation, and antiseptic prophylaxis. The arthroplasty section includes recommendations for blood transfusion, systemic immunosuppressive therapy, and antibiotics during drain use. There was low-quality evidence precluding recommendations for preoperative intra-articular corticosteroid injections, orthopedic surgical space suits, and biofilm management. The recommendations provided throughout this review, including more recent guidelines from other organizations such as the AAOS and ACR, should assist clinicians in developing and/or refining surgical site prevention protocols for their patients undergoing total joint arthroplasty procedures.

Surgeon Personal Protection: An Underappreciated Benefit of Positive-pressure Exhaust Suits

BACKGROUND

Positive-pressure exhaust suits cost more than standard surgical gowns, and recent evidence suggests that they do not decrease infection risk. As a result, some hospitals and surgeons have abandoned positive-pressure exhaust suits in favor of less expensive alternatives. We propose that in addition to their original purpose of decreasing infection rates, positive-pressure exhaust suits may also improve personal protection for the surgeon and assistants, perhaps justifying their added costs.

QUESTIONS/PURPOSES

(1) Do positive-pressure exhaust suits decrease exposure to particulate matter during TKA? (2) What areas covered by gowning systems are at risk of exposure to particulate matter?

METHODS

Three surgical gowning systems were tested: (1) surgical gown, face mask, surgical skull cap, protective eyewear; (2) surgical gown, face mask, surgical protective hood, protective eyewear; and (3) positive-pressure exhaust suit. For each procedure, a cadaver knee was injected intraarticularly and intraosseously with a 5-µm fluorescent powder mixed with water (1 g/10 mL). After gowning in the standard sterile fashion, the primary surgeon and two assistants performed two TKAs with each gowning system for a total of six TKAs. After each procedure, three independent observers graded skin exposure of each surgical participant under ultraviolet light using a standardized scale from 0 (no exposure) to 4 (gross exposure). Statistical analysis was performed using Friedman's and Nemenyi tests. The interrater reliability for the independent observers was also calculated.

RESULTS

The positive-pressure exhaust suits had less surgeon and assistant exposure compared with other systems (p < 0.001). The median overall exposure grade for each gowning system was 4 for System 1 (range, 3-4), 2.5 for System 2 (range, 2-3), and 0 for System 3 (range, 0-0). In pairwise comparisons between gowning systems, the positive-pressure exhaust suits had less exposure than gowning System 1 (difference of medians: 4, p < 0.001) and gowning System 2 (difference of medians: 2.5, p = 0.038). There was no difference found in exposure between Systems 1 and 2 (difference of medians: 1.5, p = 0.330). When gowning Systems 1 and 2 were removed, particulate matter was found in places that were covered such as the surgeon's beard, lips, inside the nostrils, behind the protective eyewear around the surgeon's eye, and in both eyebrows and eyelashes.

CONCLUSIONS

The positive-pressure exhaust suits provided greater personal protection with each procedure than the other two gowning systems.

CLINICAL RELEVANCE

With conventional gowns, particulate matter was found in the surgeon's eyelashes, under the face mask around the mouth, and inside the nostrils. Despite recent evidence that certain types of positive-pressure exhaust suits may not decrease infection, there is a clear benefit of surgeon protection from potentially infectious and harmful patient substances. Despite their added costs, hospitals and surgeons should weigh this protective benefit when considering the use of positive-pressure exhaust suits.

Surgical Space Suits Increase Particle and Microbiological Emission Rates in a Simulated Surgical Environment

BACKGROUND

The role of space suits in the prevention of orthopedic prosthetic joint infection remains unclear. Recent evidence suggests that space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause. This study aimed to compare the particle and microbiological emission rates (PER and MER) of space suits and standard surgical clothing.

METHODS

A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during 5 separate experiments. Particle counts were analyzed with 2 separate particle counters capable of detecting particles between 0.1 and 20 μm. An Andersen impactor was used to sample bacteria, with culture counts performed at 24 and 48 hours.

RESULTS

Four experiments consistently showed statistically significant increases in both PER and MER when space suits are used compared with standard surgical clothing. One experiment showed inconsistent results, with a trend toward increases in both PER and MER when space suits are used compared with standard surgical clothing.

CONCLUSION

Space suits cause increased PER and MER compared with standard surgical clothing. This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in clinical studies.

Comparison of air exhausts for surgical body suits (space suits) and the potential for periprosthetic joint infection

BACKGROUND

Periprosthetic joint infection is a major complication of total joint replacement surgery and is associated with significant morbidity, mortality and financial burden. Surgical body suits (space suits), originally designed to reduce the incidence of infection, have paradoxically been implicated in increased periprosthetic joint infection rates recently. Air exhausted from space suits may contribute to this increased rate of periprosthetic joint infection.

AIM

To investigate the flow of air exhausted from space suits commonly used in modern operating theatres.

METHODS

The exhaust airflow patterns of four commercially available space suit systems were compared using a fog machine and serial still photographs.

FINDINGS

The space suit systems tested all air exhausted into the operating room. The single fan systems with a standard surgical gown exhausted air laterally from the posterior gown fold at approximately the level of the surgical field. The single fan system with a dedicated zippered suit exhausted air at a level below the surgical field. The dual fan system exhausted air out of the top of the helmet at a level above the surgical field.

CONCLUSIONS

Space suit systems currently in use in joint replacement surgery differ significantly from traditional body exhaust systems; rather than removing contaminated air from the operating environment, modern systems exhaust this air into the operating room, in some cases potentially towards the sterile instrument tray and the surgical field.

Factors contributing to airborne particle dispersal in the operating room

Background

Surgical-site infections due to intraoperative contamination are chiefly ascribable to airborne particles carrying microorganisms. The purpose of this study is to identify the actions that increase the number of airborne particles in the operating room.

Methods

Two surgeons and two surgical nurses performed three patterns of physical movements to mimic intraoperative actions, such as preparing the instrument table, gowning and donning/doffing gloves, and preparing for total knee arthroplasty. The generation and behavior of airborne particles were filmed using a fine particle visualization system, and the number of airborne particles in 2.83 m³ of air was counted using a laser particle counter. Each action was repeated five times, and the particle measurements were evaluated through one-way analysis of variance multiple comparison tests followed by Tukey–Kramer and Bonferroni–Dunn multiple comparison tests for post hoc analysis. Statistical significance was defined as a P value ≤ .01.

Results

A large number of airborne particles were observed while unfolding the surgical gown, removing gloves, and putting the arms through the sleeves of the gown. Although numerous airborne particles were observed while applying the stockinet and putting on large drapes for preparation of total knee arthroplasty, fewer particles (0.3–2.0 μm in size) were detected at the level of the operating table under laminar airflow compared to actions performed in a non-ventilated preoperative room (P < .01).

Conclusions

The results of this study suggest that surgical staff should avoid unnecessary actions that produce a large number of airborne particles near a sterile area and that laminar airflow has the potential to reduce the incidence of bacterial contamination.

Carbon dioxide insufflation deflects airborne particles from an open surgical wound model

BACKGROUND

Surgical site infections remain a significant burden on healthcare systems and may benefit from new countermeasures.

AIM

To assess the merits of open surgical wound CO₂ insufflation via a gas diffuser to reduce airborne contamination, and to determine the distribution of CO₂ in and over a wound.

METHODS

An experimental approach with engineers and clinical researchers was employed to measure the gas flow pattern and motion of airborne particles in a model of an open surgical wound in a simulated theatre setting. Laser-illuminated flow visualizations were performed and the degree of protection was quantified by collecting and characterizing particles deposited in and outside the wound cavity.

FINDINGS

The average number of particles entering the wound with a diameter of <5μm was reduced 1000-fold with 10L/min CO₂ insufflation. Larger and heavier particles had a greater penetration potential and were reduced by a factor of 20. The degree of protection was found to be unaffected by exaggerated movements of hands in and out of the wound cavity. The steady-state CO₂ concentration within the majority of the wound cavity was >95% and diminished rapidly above the wound to an atmospheric level (∼0%) at a height of 25mm.

CONCLUSION

Airborne particles were deflected from entering the wound by the CO₂ in the cavity akin to a protective barrier. Insufflation of CO₂ may be an effective means of reducing intraoperative infection rates in open surgeries.

Do 'Surgical Helmet Systems' or 'Body Exhaust Suits' Affect Contamination and Deep Infection Rates in Arthroplasty? A Systematic Review

This systematic review examined whether negative-pressure Charnley-type body exhaust suits (BES) or modern positive-pressure surgical helmet systems (SHS) reduce deep infection rates and/or contamination in arthroplasty. For deep infection, four studies (3990 patients) gave adjusted relative risk for deep infection of 0.11 (P = 0.09) against SHS. Five of 7 (71%) studies found less air contamination and 2 of 4 studies (50%) less wound contamination with BES. One of 4 (25%) found less air contamination with SHS and 0 of 1 (0%) less wound contamination. In contrast to BES, modern SHS designs were not shown to reduce contamination or deep infection during arthroplasty.

The Gown-glove Interface Is a Source of Contamination: A Comparative Study

BACKGROUND

The original Charnley-type negative-pressure body exhaust suit reduced infection rates in randomized trials of total joint arthroplasty (TJA) decades ago. However, modern positive-pressure surgical helmet systems have not shown similar benefit, and several recent studies have raised the question of whether these gowning systems result in increased wound contamination and infections. The gown-glove interface may be one source of particle contamination.

QUESTIONS/PURPOSES

The purpose of this study was to compare particle contamination at the gown-glove interface in several modern surgical helmet systems and conventional surgical gowns.

METHODS

A 5-μm fluorescent powder was evenly applied to both hands to the level of the wrist flexion crease. After gowning in the standard fashion, the acting surgeon performed a 20-minute simulated TJA protocol. Each of the five gowning systems was run through five trials. The amount of gown contamination at the gown-glove interface then was measured by three observers under ultraviolet light using a grading scale from 0 (no contamination) to 4 (gross contamination). Statistical analysis was carried out with Minitab 15. Friedman's test was used to compare the levels of contamination across trials for each gown and the Mann-Whitney test was used post hoc to perform a pairwise comparison of each gown.

RESULTS

All gown-glove interfaces showed some contamination. Friedman's test showed that there was a significant difference in contamination between gowns (p = 0.029). The Stryker T5 Zipper Toga system showed more contamination than the other gowns. The median contamination score and range for each gowning setup was 1.8 (range, 1-4; conventional Kimberly-Clark MicroCool gown without helmet), 4 (range, 3-4; Stryker T5 Zipper Toga), 3.6 (range, 0-4; Stryker helmet with conventional gown), 1.6 (range, 0-2; Stryker Flyte Toga), and 3.0 (range, 2-3; DePuy Toga). A Mann-Whitney test found no difference among any of the gowns except for the Stryker T5 Zipper Toga, which showed more contamination compared directly with each of the other four gowns (p < 0.001 for each gown-to-gown comparison).

CONCLUSIONS

Particle contamination occurs at the gown-glove interface in most commonly used positive-pressure surgical helmet systems. The Stryker T5 Zipper Toga exhibited more contamination than each of the other gowning systems.

CLINICAL RELEVANCE

The gown-glove interface is prone to particle contamination and all surgeons should be aware of this area as a potential source of surgical site infection. Although future studies are needed to clarify the link between particle contamination through this route and clinical infection, surgeons should consider using gowning systems that minimize the migration of fomites through the gown-glove interface.

Preventing surgical-site infections: measures other than antibiotics

Surgical-site infections (SSIs) due to intra-operative contamination are chiefly ascribable to airborne particles carrying microorganisms, mainly Staphylococcus aureus, which settle on the surgeon's hands and instruments. SSI prevention therefore rests on minimisation of airborne contaminated particle counts, although these have not been demonstrated to correlate significantly with SSI rates. Maintaining clear air in the operating room classically involves the use of ultra clean ventilation systems combining laminar airflow and high-efficiency particulate air filters to create a physical barrier around the surgical table; in addition to a stringent patient preparation protocol, appropriate equipment, and strict operating room discipline on the part of the surgeon and other staff members. SSI rates in clean surgery, although influenced by the type of procedure and by patient-related factors, are consistently very low, of about 1% to 2%. These low rates, together with the effectiveness of prophylactic antibiotic therapy and the multiplicity of parameters influencing the SSI risk, are major obstacles to the demonstration that a specific measure is effective in decreasing SSIs. As a result, controversy surrounds the usefulness of many measures, including laminar airflow, body exhaust suits, patient preparation techniques, and specific surgical instruments. Impeccable surgical technique and operating room behaviour, in contrast, are clearly essential.

Surgical attire, practices and their perception in the prevention of surgical site infection

INTRODUCTION

Clean surgical scrubs, surgical gowns and headgear are worn by operative teams to decrease bacterial contamination and lower surgical site infection (SSI) rates.

METHODS

A detailed review was undertaken of peer-reviewed publications and other sources of material in the English language over the last 50 years included.

RESULTS

Surgical scrubs should be clean and made of tightly woven material. Studies investigating single-use gowns and drapes versus reusable gowns report conflicting evidence. Double gloving may reduce SSI rates in procedures where no antibiotic prophylaxis was administered. Bacterial contamination of the operative field has been shown to be decreased by the wearing of surgical headgear by the operating team.

CONCLUSIONS

Further consideration and better trials are required to determine the impact of different theatre clothing on SSI rates.

Intraoperative contamination and space suits: a potential mechanism

The body exhaust suit (BES) of Charnley creates 'negative pressure' inside the gown using intake/outtake tubing. Modern 'space suit' (SS) systems incorporate helmet-based intake fans, which use the hood material as a filter and create 'positive pressure' inside the gown. While early studies of BES demonstrate a clear reduction in infection rates following arthroplasty, recent clinical data on SS use has paradoxically reported a marked increase. We hypothesized that the positive pressure inside the gown could carry air and particles via the unsealed area around the surgeon's cuff into the operative field. We performed 12 simulated operations with the surgeons hands covered in fluorescent 0.5 micron powder that approximates the size of shedded skin squames. Photographs under UV light and air particle counts were used to compare potential contamination rates between SS and conventional gowns using a standardised scoring system. The highest powder migration was seen in the SS group with a score of 15.3 out of 28. No powder migration was seen in the standard gown group (p = 0.028). This study provides a plausible explanation for the increase in infection rates seen with SS use. We recommend SS be considered for personal protection only and supplemented with sealant tape around the inner glove.

Air sampling methods to evaluate microbial contamination in operating theatres: results of a comparative study in an orthopaedics department

AIM

To evaluate the level of microbial contamination of air in operating theatres using active [i.e. surface air system (SAS)] and passive [i.e. index of microbial air contamination (IMA) and nitrocellulose membranes positioned near the wound] sampling systems.

METHODS

Sampling was performed between January 2010 and January 2011 in the operating theatre of the orthopaedics department in a university hospital in Southern Italy.

FINDINGS

During surgery, the mean bacterial loads recorded were 2232.9 colony-forming units (cfu)/m(2)/h with the IMA method, 123.2 cfu/m(3) with the SAS method and 2768.2 cfu/m(2)/h with the nitrocellulose membranes. Correlation was found between the results of the three methods. Staphylococcus aureus was detected in 12 of 60 operations (20%) with the membranes, five (8.3%) operations with the SAS method, and three operations (5%) with the IMA method.

CONCLUSION

Use of nitrocellulose membranes placed near a wound is a valid method for measuring the microbial contamination of air. This method was more sensitive than the IMA method and was not subject to any calibration bias, unlike active air monitoring systems.

Sterility of the personal protection system in total joint arthroplasty

BACKGROUND

Bacteria shed by operating room personnel is a source of wound contamination and postoperative infections. The personal protection system (PPS) was designed to decrease airborne bacteria and intraoperative contamination in total joint arthroplasty.

QUESTIONS/PURPOSES

We determined the microbial contamination rate of the PPS and incidence of contamination with key pathogens, Staphylococcus aureus and coagulase-negative staphylococci.

PATIENTS AND METHODS

We prospectively evaluated PPS contamination in 61 primary THAs and 41 TKAs. The PPS were assumed to be sterile before opening the packs. The initial culture was taken immediately after the hood was placed over the helmet. Four cultures were collected at the conclusion of the procedure. Plates were examined and colonies were classified according to Gram stain results and biochemical tests. S. aureus was classified as methicillin-resistant or -susceptible.

RESULTS

At time zero, 22 of 102 cultures isolated an organism, accounting for a contamination rate of 22%. The bacterial contamination rate of the PPS at the conclusion of the procedure was 47% (48 of 102). The relative percentage of the various organisms found was coagulase-negative staphylococci 50%, Micrococcus sp. 20%, methicillin-susceptible S. aureus 11%, and methicillin-resistant S. aureus (MRSA) 1%.

CONCLUSIONS

The external surface of the PPS cannot be assumed to be sterile after its removal from the original packaging. Of all the PPS studied, the potential pathogens coagulase-negative staphylococcus, S. aureus, and MRSA were found in 43%. This study supports the need to change gloves if the PPS is touched or adjusted during the procedure.

Preoperative chlorhexidine preparation and the incidence of surgical site infections after hip arthroplasty

The purpose of this study was to evaluate effectiveness of an advance, at-home chlorhexidine-impregnated skin preparation cloth in decreasing the incidence of deep periprosthetic hip arthroplasty infections. Arthroplasty surgeons at the senior author's institution provided their patients with chlorhexidine-impregnated single-use cloths for use at home the night before and the morning of surgery. Between January 2007 and December 2009, the compliance of this practice, as well as the incidence of periprosthetic infections, was monitored for all patients who underwent hip arthroplasty. Of the 1134 patients who underwent hip arthroplasty, 157 patients completely complied with the preoperative chlorhexidine preparation protocol. There were 14 infections in the group that was not compliant (1.6% infection rate), and there were no infections in the compliant patient population. Based on the results of this study, at-home preoperative patient skin preparation appears to be a simple and cost-effective method to reduce periprosthetic hip infection rates.

The "six sigma approach" to the operating room environment and infection

The patient's external environment plays a significant, and in some cases dominant, role in his or her infection risk. The use of ultraclean air for certain procedures, as well as avoidance of hypothermia have been proven to reduce the risk of infection. There is no data to support the routine use of surgical masks (by surgeons or staff), ventilating helmets, or routine cleaning of all environmental surfaces in between cases. More research needs to be done in order to determine whether OR design changes, in addition to increasing OR efficiency and thus reducing case times, can also reduce infection rates. Further research is also needed to determine whether or not double gloves and/or the use of antiseptic scrubbing in addition to painting are efficacious.

Lowbury Lecture 2005: infection control from a global perspective

All healthcare settings around the world face the problem of healthcare-associated infections (HCAIs). Rates of infection vary between countries and within the same country depending on resources, interest of caregivers and healthcare staff, and patients' socio-economic situation. According to recent publications, 10-70% of HCAIs are preventable. Failure to comply with guidelines on hand hygiene, glove and gown use, and barrier nursing is a problem and unnecessary infection control measures are costly. National legislations and regional, national and international standards and guidelines associated with infection control also have an impact for countries that are not directly involved. They should be based on the assessment of infection risk, and should not increase costs unnecessarily. The International Federation of Infection Control and national infection control societies play an important role in continuing the education of infection control specialists.

Transmission and prevention of occupational infections in orthopaedic surgeons

Microorganisms are transmitted in hospitals mainly by contact, droplet, and airborne routes. Orthopaedic surgeons have a substantial occupational risk of contracting a blood-borne infection because of frequent handling of sharp instruments and objects during operative procedures. Aerosolization means the formation of aerosols and droplets when blood or other body fluids are mechanically disturbed. Smaller particles (<5 microm) will remain suspended in air. Pathogens that can survive in these small airborne particles may cause infection if they are inhaled. Aerosol-generating procedures in patients with tuberculosis or severe acute respiratory syndrome (SARS) may facilitate airborne transmission. The Hospital Infection Control Practices Advisory Committee and the Centers for Disease Control and Prevention have established guidelines for isolation precautions in hospitals.