On the value and limitations of incorporating a "clean phase" into the surgical treatment of prosthetic joint infections - an illustrative cadaveric study using fluorescent powder

Purposes

A septic revision of an artificial joint is routinely split up in a so-called dirty phase and a clean phase. The measures taken to initiate the start of the clean phase vary significantly between musculoskeletal infection centers. We performed simulations of one-step exchanges of infected THAs and sought to 1) determine the effect of different clean phase protocols on the sterile field, and 2) determine whether or not it is possible to re-implant the new prosthesis completely clean.

Methods

Nine fresh frozen cadaveric hips were used and primary THA was undertaken via a direct anterior approach. Before implantation of the components varying amounts of fluorescent powder (GloGerm) were deposited, simulating bacterial infection. Second, a one-step exchange was performed via a posterolateral approach. After implant removal, debridement, and lavage, randomization determined which clean phase protocol was followed, i.e. no, some or full additional measures. Finally, the new prosthesis was re-implanted.

In order to determine the effect of different clean phase protocols on contamination of the sterile field standardized UV light-enhanced photographs were obtained of 1) the gloves, 2) the instrument table, 3) the drapes, and 4) the wound and these were ranked on cleanliness by a blinded panel of hip surgeons.

In order to determine whether or not it is possible to re-implant the prosthesis completely clean, the implant was taken out again at the end of the one-step exchange and inspected for contamination under UV light.

Results

The gloves, the instrument table, the drapes and the wound were significantly cleaner after a clean phase using full additional measures compared to partial or no additional measures (p < 0.000). Partial measures were able to reduce some of the contamination of the gloves and the wound, but had no effect on the drapes and the instrument table. All re-implanted implants were contaminated with some amount of fluorescent powder at the end of the one-step exchange.

Conclusions

We advise to incorporate a clean phase with full additional measures into the surgical treatment of prosthetic joint infections, as partial measures seem to be a poor compromise.

Level of evidence

Not applicable (cadaveric study).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00467-x.

Minimizing contamination in the use of personal protective equipment: Simulation results through tracking contamination and enhanced protocols

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Our enhanced protocols presented a significant reduction in doffing contaminations.

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Long-sleeve apron as the broad outer layer perfectly protected major contaminations.

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Tracking contamination showed every touch with outer surfaces brought contamination.

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Wipes certainly decreased contamination amounts from contaminated glove surfaces.

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But wipes did not fully clean glove contaminations between fingers and fingertips.

Background

Due to variations and the inadequate use of personal protective equipment (PPE), this study aimed to evaluate our enhanced PPE protocols for minimizing doffing contamination.

Methods

Among 3 PPE kits (simple, Level D, and Level C), 30 participants conducted the first simulation in their adapted way and the second following enhanced protocols. After donning, participants performed a 1-minute simulation of direct care on a patient simulator covered with fluorescent powder. For tracking contamination routes between doffing processes, fluorescent powder contamination was examined with ultraviolet lamps in the darkened room.

Results

Participants were mostly registered nurses (N = 27, 90%), female (87%), and on average 31.7 years old with 8.5 years of clinical experience. Among 61 total simulations, 32 had at least 1 contamination (52.5%); “Noticeable” level (40%) at the “hands-fingers” and “shirt” body areas were most frequent. For first and second simulations with identical PPE kits, compared to the first with adapted practice, the second with enhanced protocols showed a significant reduction in doffing contamination rates (72.7% vs 22.7%, P = .0009 for both Level C and D; 77.8% vs 27.8%, P = .0027 for Level D).

Conclusions

Our enhanced protocols could significantly reduce contaminations. More studies are necessary to provide safer PPE protocol options.

Rare earth elements recovery from secondary wastes by solid-state chlorination and selective organic leaching

Processing of end-of-life products (EoL) containing rare earth elements (REE) has gained increasing importance in recent years with the aim of avoiding supply risks. In addition, circular economy renders complete recirculation of technology metals mandatory. Fluorescent lamp wastes are an important source for REE recovery since they contain significant amounts, up to 55 wt%, of Y and Eu in red phosphors. For these purposes, solid-state chlorination (SSC) is an economically attractive alternative to wet acid leaching treatment, which profits from a considerable reduction of chemicals consumption and process costs. Chlorination takes place with dry HCl_(g) produced from thermal decomposition of NH₄Cl_(s), not only converting the REE content of the Hg-free phosphor waste into water soluble REE metal chlorides, but also avoiding the implications of aqueous complex chemistry of REE. To establish an industrial process viable on a commercial scale, the SSC process has been optimized by (i) using a design of experiment (DOE) varying temperature, residence time, and g_NH4Cl/g_solid ratio and (ii) improved leaching of the chlorinated metals with an organic mixture selective for REE. As a result, 95.7% of the Y and 92.2% of the Eu were selectively recovered at 295.9 °C, 67 min and a ratio of 1.27 g_NH4Cl/g_solid, followed by quantitative selective leaching of the REE. Owed to its low chemicals consumption and operation costs, the current process allows for valorizing lamp waste even when raw material prices are low.

Impacts of fluorescent powders on survival of different age cohorts, blood-feeding success, and tethered flight speed of Aedes aegypti (Diptera: Culicidae) females

Fluorescent powders are one of the most common external markers used to study mosquito behavior and ecology. For their reliable and practical use, it is important to evaluate their effect on biological parameters such as survival, blood-feeding, and mobility. We evaluated the effect of five different fluorescent powders (Day-Glo ® ECO Series) on the survival of different age cohorts, blood-feeding success, and tethered flight speed on Aedes aegypti (Linnaeus) adult females. For survival analysis, three cohorts (2-5, 6-9 and 10-13 days old) were marked and mortality recorded until all died. To examine the effect of fluorescent powders on female response to blood-feeding, the proportions of unfed, partially fed, and fully engorged females, after being exposed to host blood under two different time sets (20 and 40 min.), were compared. Their impact on female tethered flight speed was evaluated recording their flight for 30 min. with a flight mill. Survival distributions between treatments were not significantly different within each cohort. Blood-feeding was not significantly different among marked or unmarked females at both times of blood exposure, with the exception of Signal Green-ECO 18 and Ultra Violet- ECO 20 (at 20 and 40 min.), in which a higher proportion of partially fed females was observed compared to control females. In relation to flight performance, no statistically significant difference in mean tethered flight speed (m/s), among marked and unmarked mosquito groups, was observed. Our results indicate that the tested powders and application method have few significant impacts on Ae. aegypti survival, blood-feeding success and flight performance, and are thus suitable for investigations of mosquito biology in the environment.

Life cycle assessment of rare earths recovery from waste fluorescent powders - A case study in China

Life cycle assessment of recycling rare earths from waste fluorescent powders was conducted, including the uncertainty and sensitivity analyses. Three scenarios were set in this study, namely, recycling with/without final disposal and waste fluorescent powders landfill. Recycling with final disposal presented lower environmental burden than that without final disposal due to the significant reduction of direct emissions. The evident impacts from chemicals and energy production stages were considered the main contributors to the overall environmental burden of recycling with final disposal due to their relatively high emissions of particulates matter, sulfur dioxide, heavy metals, and carbon dioxide as well as the use of fossil fuel. Compared with landfills, rare-earth recycling shows the highest environmental benefits because of the substitution of primary rare earths. To relieve the high demand of rare earths and reduce the overall environmental burden, governments are highly recommended to increase recycle rate, create a complete management system, improve energy consumption and wastewater treatment efficiency, and build an adequate recycle standard.

Use of personal protective equipment among health care personnel: Results of clinical observations and simulations

BACKGROUND

Very little is known about how health care personnel (HCP) actually use personal protective equipment (PPE).

METHODS

The clinical PPE practices of 50 HCP from selected units at the University of Pittsburgh Medical Center (UPMC) Presbyterian Hospital were videotaped with HCP consent. For 2 PPE simulation sessions (simple and full-body sets), 82 HCP were recruited throughout the UPMC system. Simulation practices were videotaped and examined using fluorescent powder with ultraviolet lighting. All participants completed an electronic survey. For a follow-up evaluation simulation, 12 HCP were recruited among simulation participants.

RESULTS

Among 130 total sessions from 65 participants, contamination occurred in 79.2% of simulations during the doffing process with various PPE items: simple set (92.3%) and full-body set (66.2%). Among 11 follow-up evaluation participants, contaminations still occurred in 82% after receiving individual feedback, but the overall contamination level was reduced. Using the contamination information gained during the simulation analysis, 66% of potential contamination was estimated for the clinical observation. Concerns and barriers in PPE use from HCP survey responses were as follows: time-consuming, cumbersomeness, and PPE effectiveness.

CONCLUSIONS

Although HCP knew they were being videotaped, contamination occurred in 79.2% of the PPE simulations. Devising better standardized PPE protocols and implementing innovative PPE education are necessary to ensure HCP safety.

Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2(2) full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3M of sulphuric acid, 10% v/v of H2O2 concentrated solution at 30% v/v, 10% w/w pulp density, 70°C and 3h of reaction. Two series of precipitation tests for zinc are carried out: a 2(2) full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2-2.5% and 10-12%v/v of Na2S concentrated solution at 10%w/v. In these conditions the coprecipitation of yttrium is of 15-20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75-80%.