Impact of surface tension on the barrier performance of gowns and coveralls

BACKGROUND

Health care workers and laboratory workers who are routinely exposed to potentially life-threatening infectious diseases should wear protective clothing when anticipating contact with infectious materials. The most critical property of protective clothing is its ability to prevent liquids and viruses from passing through the garment. There are a number of potentially infectious liquids that workers may be exposed to during routine tasks. Each liquid has different physical and chemical properties that affect penetration. However, the current test methods use a limited number of liquids for classifying the barrier performance. The impact of the surface tension of the challenge liquid on the penetration resistance of gowns and coveralls was investigated in this study.

METHODS

Eight isolation gowns and 2 coveralls were tested in accordance with American Association of Textile Chemists and Colorists 42 and American Association of Textile Chemists and Colorists 127 test methods, which were modified to incorporate the substitute challenge liquids.

RESULTS

Although current standard test methods only use water to categorize the liquid penetration resistance of minimal to moderate barrier performance gowns, a significant difference in the penetration was found when simulated body fluids were used.

CONCLUSIONS

The results suggest that safety professionals and wearers should consider the varying barrier performance of personal protective equipment with different liquids and the use limitations when selecting them for the required tasks. Furthermore, standard development organizations should consider multiple challenge liquids when classifying protective clothing for health care settings.

Evaluation of fluid leakage at the coverall and glove interface in single and double glove conditions

BACKGROUND

Fluid leakage through the glove-protective clothing interface is an area of concern for many health care personnel, including emergency medical service providers, who may wear coveralls to protect themselves from multiple types of hazards. There is currently no established standard test method to specifically evaluate the barrier performance of the glove-protective clothing interface region for any personal protective equipment ensemble.

OBJECTIVE

This study quantifies the fluid leakage at the coverall and glove interface using single and double gloving.

METHODS

A robotic arm, which can simulate upper extremity movements of health care personnel, was used to test 5 coverall models and an extended examination glove model in single and double glove conditions.

RESULTS

The results show that there was a significant difference in fluid leakage amounts between some of the coverall models and the number of glove layers studied. Findings also highlight that there is a high correlation between basis weight and stiffness of the coverall fabrics and the fluid leakage amounts.

CONCLUSIONS

These results underline that coverall constructed from thin and less stiff fabrics can result in lower fluid leakage levels. Also, there was no significant difference in fluid leakage amounts between single and double gloves when tested with each of the coverall models, with the exception of the coveralls with the highest basis weight and stiffness.

A simulation study to assess fluid leakage through the glove-gown interface in isolation settings

BACKGROUND

Isolation gowns are recommended to protect healthcare personnel, patients, and visitors from transfer of microorganisms and body fluids in patient isolation situations. Standards provide limited information about barrier performance of isolation gowns for possible exposure scenarios. One of the most vulnerable areas of the personal protective equipment ensemble is considered the glove-gown interface. However, current isolation gown classification standards do not consider the interface regions of the personal protective equipment system while assessing the level of protection. The purpose of this study was to quantitatively evaluate the fluid leakage through the glove-gown interface by simulating exposures and healthcare personnel arm movements in patient care for isolation settings.

METHODS

We tested fluid leakage of two examination gloves with different cuff lengths and seven isolation gown models designed with varying levels of barrier resistance and multiple cuff types.

RESULTS

Our results demonstrated that leakage through the glove-gown interface depends on multiple factors, including glove cuff length and gown cuff design. Gowns with the thumb loop design provided better protection than the elastic cuff design, and the elastic cuff design provided better protection compared to the knit cuff design for a given AAMI PB70 level. More importantly, a substantial penetration through gown fabrics was observed.

CONCLUSIONS

This research identifies a need to develop a standardized method to evaluate leakage at the glove-gown interface to improve worker protection.

Barrier resistance of double layer isolation gowns

Background

Isolation gowns are one of the crucial pieces of personal protective equipment (PPE) to prevent the migration of microorganisms and body fluids from patients to health care personnel and vice versa. Underperforming isolation gowns in terms of fluid resistance, could potentially put lives in danger. Wearing multiple layers of isolation gowns could theoretically increase the fluid penetration resistance. This study investigates if 2-layer lower barrier level isolation gowns meet the barrier effectiveness requirements of a single higher barrier level isolation gown.

Methods

Three commonly used ANSI/AAMI Level 2 isolation gown models were selected and tested in single layer and double layer configurations in accordance with ANSI/AAMI PB70 requirements.

Results

Total of 240 experiments were conducted to analyze the effects of gown model, fabric region, and the number of gown layers on AATCC 127 and AATCC 42 test results. In regard to AATCC 42, there was a significant difference among the different gown models, and the number of gown layers. Similar to AATCC 42 results, there was a significant difference among the different gown models, and the number of gown layers for AATCC 127; additionally, the gown regions was also significantly different.

Conclusion

Test results demonstrated that the double layer isolation gown configurations do not always provide equal fluid penetration resistance as required for a single Level 3 isolation gown using the standard test methods specified in ANSI/AAMI PB70.

Critical investigation of glove-gown interface barrier performance in simulated surgical settings

The barrier properties of personal protective equipment are vital to healthcare personnel to protect themselves from possible infectious body fluids. Intraoperative exposure of healthcare personnel to body fluids can be substantial in both inpatient and outpatient settings. The glove-gown interface is known as one of the weakest points of the whole personal protective equipment system. However, there is a lack of scientific research designed to investigate the problem. This paper reports the results of experiments using a new testing methodology developed to quantify fluid leakage through the glove-gown interface while simulating surgical settings in terms of operating room personnel activities, exposure types, exposure durations, and physical stresses applied on the interface. This study represents one of the first efforts investigating the amount of fluid leakage through the glove-gown interface for a number of surgical gown and glove models while considering glove material differences and single vs. double gloving. The test results showed that there is a significant difference in fluid leakage amounts between three gown models and four glove models studied. The results also demonstrated that double gloving significantly reduced the fluid leakage compared to single glove use. The mean fluid leakage was lower in the double synthetic glove configurations (M = 2.76g) compared with all other configurations (3GLV, M = 8.3g; 4GLV, M = 9.49g; 5GLV, M = 3.08g; 6GLV, M = 20.03g; double latex, M = 5.22g). Findings highlighted a significant interaction between glove and gown designs, which suggests that gown and gloves should be designed together as a system to minimize or eliminate the fluid leakage.

Novel Test Method for the Evaluation of Fluid Leakage at the Glove-Gown Interface and Investigation of Test Parameters

BACKGROUND

Exposure to patients' blood/body fluids could be life-affecting, when providing care to patients with infectious diseases. Although the glove-gown interface is considered one of the weakest points of the protective ensemble system, there is a lack of research, and existing standards do not provide much guidance on strategies to minimize gaps between the gowns and gloves. Currently, there is no known standard test method to evaluate fluid leakage or assess performance improvements with new gowns/gloves.

STUDY DESIGN

A novel test method with a robotic arm, which has the capability to simulate health care personnel's arm movements during fluid exposure, was developed to determine the leakage at the glove-gown interface. This article explains the test method and investigates the effect of movement, exposure type, exposure duration, procedure duration, and existence of pressure on the amount of leaked fluid at the glove-gown interface.

RESULTS

Test results suggest that, with the exception of procedure duration, all parameters significantly affected the amount of fluid leaked at the glove-gown interface. Leakage was higher for soaking when compared to spraying, increased as the exposure duration increased, and was greater with the application of pressure.

CONCLUSIONS

The novel method developed in this study could be used by manufacturers of personal protective equipment to evaluate their products. Standard development organizations could adapt this test method in their specifications, testing standards, and guidelines.

Highly porous photoluminescent diazaborole-linked polymers: synthesis, characterization, and application to selective gas adsorption

Highly porous and photoluminescent diazaborole-linked polymers are targeted by boron–nitrogen bond formation through simple condensation reactions. The resultant polymers exhibit remarkable gas uptake and tunable photoluminescent properties.

Enhanced Carbon Dioxide Capture from Landfill Gas Using Bifunctionalized Benzimidazole-Linked Polymers

Tuning the binding affinity of small gases and their selective uptake by porous adsorbents are vital for effective CO2 removal from gas mixtures for environmental protection and fuel upgrading. In this study, an amine-functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized by a combination of pre- and postsynthetic modification techniques in two steps. Presynthetic incorporation of nitro groups resulted in stoichiometric functionalization (1 nitro/phenyl) in addition to noninvasive functionalization, where more than 80% of the surface area maintained compared to BILP-6. Experimental studies presented enhanced CO2 uptake and CO2/CH4 selectivity in BILP-6-NH2 compared to BILP-6, which are governed by the synergetic effect of benzimidazole and amine moieties. DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2 and confirmed the efficacy of amine groups. Encouraged by the enhanced uptake and selectivity in BILP-6-NH2, we have evaluated its performance in landfill gas separation under vacuum swing adsorption (VSA) settings, which resulted in very promising working capacity and sorbent selection parameters outperforming most of the best solid adsorbent in the literature.

Selective recognition and imaging of bacterial model membranes over mammalian ones by using cationic conjugated polyelectrolytes

This work describes the use of cationic polyfluorenes as fluorescent markers to selectively recognize bacterial membranes.

Using microwave irradiation in Marchi's method for demonstrating degenerated myelin

Conventional methods for histological preparation of degenerated myelin are time-consuming and difficult. The purpose of our study was to shorten the time required for the procedure and to obtain better quality results for light microscopic demonstration of degenerated myelin in the central and peripheral nervous systems by using microwave irradiation. Rat brain and sciatic nerve were used for the study. The middle cerebral artery was occluded and the sciatic nerve was cut to produce myelin degeneration. Marchi's method was used for staining degenerated myelin. Fixation for light microscopy that would take two days using the conventional procedure was completed in 16.5-18.5 min using microwave irradiation. While staining of degenerated myelin requires 10 days for the conventional Marchi method, we decreased it to 7 h for brain tissue and 1 h for sciatic nerve by using the microwave oven. Moreover, a better quality preparation was achieved in the groups stained under microwave irradiation than those prepared by the conventional method.

A simple and rapid microwave-assisted hematoxylin and eosin staining method using 1,1,1 trichloroethane as a dewaxing and a clearing agent

The use and practicability of microwave-assisted staining procedures in routine histopathology has been well established for more than 17 years. In the study reported here, we aimed to examine an alternative approach that would shorten the duration of dewaxing and clearing steps of hematoxylin and eosin (H & E) staining of paraffin sections by using a microwave oven. Although xylene is one of the most popular dewaxing and clearing agents, its flammability restricts its use in a microwave oven; thus we preferred 1,1,1 trichloroethane, which is not flammable, as the dewaxing and clearing agent in the present study. In Group I and Group II (control groups), intestine was processed with xylene and 1,1,1 trichloroethane, respectively. The sections were then stained with H & E according to the conventional staining protocol at room temperature and subdivided into two groups according to the duration of dewaxing and clearing in xylene. In Groups III and IV (experimental groups) similar tissues were processed with xylene and 1,1,1 trichloroethane, respectively; however, sections from these groups were divided into four subgroups to study the period required for dewaxing and clearing in 1,1,1 trichloroethane, then stained with H & E in the microwave oven at 360 W for 30 sec. Our conventional H & E staining procedure, which includes dewaxing, staining and clearing of sections, requires approximately 90 min, while our method using 1,1,1 trichloroethane and microwave heating required only 2 min. Our alternative method for H & E staining not only reduced the procedure time significantly, but also yielded staining quality equal or superior to those stained the conventional way. Our results suggest that 1,1,1 trichloroethane can be used effectively and safely as a dewaxing and clearing agent for H & E staining in a microwave oven.

A comparison of microwave heating and proteolytic pretreatment antigen retrieval techniques in formalin fixed, paraffin embedded tissues

Antigen retrieval (AR) is a technique that re-exposes epitopes in formalin fixed, paraffin embedded sections and makes them detectable by immunohistochemistry. We compared the effects of two AR procedures, enzyme digestion and microwave heating, on immunostaining of vimentin and desmin in formalin fixed, paraffin embedded tissues. Our results showed that AR is necessary for vimentin and desmin immunostaining in tissues fixed in formalin for more than 48 h. With prolonged fixation times, microwave heating showed better results than enzyme digestion for AR. The same results were obtained using 1% zinc sulfate or Citra Plus solution as retrieval solutions for microwave heating. We recommend microwave heating for AR, because it is easier to use and produces better results compared to enzyme treatment.

Rapid Bielschowsky silver impregnation method using microwave heating

The Bielschowsky silver impregnation method has been used extensively to demonstrate neuronal processes including dendrites, axons and neurofibrils. In this study, we examined the differences in the time required for and the staining quality of the Bielschowsky method for neuronal processes when microwave heating was used instead of processing at room temperature. For this purpose, a control group of sections stained according to the conventional method at room temperature was compared to an experimental group stained in a microwave oven at 180 W for 2, 4 and 1 min in 2% silver nitrate, ammoniacal silver nitrate and gold chloride, respectively. Light microscopic examination demonstrated that the normal structure was preserved in both groups and that there was no difference in the staining quality between the control and the microwave groups. In addition, staining time for this procedure was reduced to 8 min by using the microwave oven. Our study revealed that microwave irradiation can be used safely for Bielschowsky silver impregnation of neuronal tissues.

Safranin O staining using a microwave oven

We investigated the effects of microwave irradiation on a safranin O staining method for paraffin sections of formalin fixed rabbit larynx. The control sections were stained according to the conventional method, and the experimental sections were stained in microwave oven for 10 sec at 360 W in Weigert's iron hematoxylin, and for 30 sec at 360 W in fast green and 0.1% safranin O staining solutions. Light microscopic examination of the sections revealed that the microwave heating did not adversely affect the staining properties of cartilage tissue compared to the conventional staining method. Small differences such as darker staining of the matrix and shrinkage of the cytoplasm was observed in some microwave treated sections. The present study revealed that microwave application can be used safely for the safranin O method with the advantage of reduced staining time.

An experimental study of bilateral repositioning of the Stensen's duct orifices with autologous vein and artery grafts in dogs

Sialorrhoea is an indication of dysfunction in the coordination of the swallowing mechanism. Disturbance in this coordination results in excess pooling of saliva in the anterior mouth and resultant drooling. Several surgical techniques have been described for the management of sialorrhoea. In this experimental study, we planned to try a more safe and physiologic technique by repositioning of the parotid duct orifices into the glossopalatal arch, using autologous free grafts of vein and artery in dogs. Ten adult dogs were used. In each dog, both of the parotid duct orifices were included in the study. The surgical procedure involved the dissection of both parotid duct orifices and their relocation via a submucosal tunnel into the glossopalatal arch, using a vein graft for the right side and an artery graft for the left side. Functional assessment was based on the clinical observations and retrograde sialography done on the 60th day. Results were excellent. No stricture or obstruction was noted. Histological examinations done on the 90th day showed the replacement of endothelium by multilayered cubic Stensen's duct epithelium in both artery and vein grafts. There was no difference between the results of artery and vein grafts. Surgical transposition of Stensen's duct into the glossopalatal arch with autologous vein or artery graft is a safe technique which may be used in clinical cases of drooling as an alternative to the other techniques described.

Effects of microwave irradiation and chemical fixation on the localization of perisinusoidal cells in rat liver by gold impregnation

Modified gold impregnation is one of the methods that are used in light microscopical demonstration of hepatic perisinusoidal cells. This method has some disadvantages, such as restriction of fixation time to 16 h, which allows limited time for processing the tissues, especially when dealing with a large amount of material, and a long impregnation time (16-24 h). We investigated the effect of prolonged fixation on the staining of sections, to shorten the time needed for gold impregnation by using microwave irradiation. Liver specimens were fixed in Baker's calcium-formalin for different periods of time. After fixation, frozen sections were impregnated in gold chloride solution either at room temperature or in a microwave oven. The staining quality of the sections which had been impregnated in the microwave oven for a much shorter time were equal to or even superior to the ones impregnated at room temperature. Prolonging the fixation time up to 7 days did not affect the staining results by microwave irradiation, whereas satisfactory results were not obtained from sections stained at room temperature and fixed for more than 3 days. We conclude that microwave irradiation can be used to shorten the impregnation time in gold chloride solution and the duration of fixation can be prolonged up to 3 days in the original method and up to 7 days when microwave irradiation is used during impregnation.

Rapid staining of ultrathin sections with the use of a microwave oven

The microwave oven has many potential applications, ranging from tissue fixation to staining for light and electron microscopy. This study was planned to speed up the staining of ultrathin sections. The first set of grids was stained conventionally with uranyl acetate and Reynold's lead citrate solutions. The other grids were stained with the same solutions by microwave irradiation. The electron micrographs of grids stained using the microwave technique were as satisfactory as the grids stained conventionally. Microwave-treated grids demonstrated more uniform staining and less precipitate. The use of a microwave oven shortened staining time by approximately 38 min.

Microwave fixation of whole fetal specimens

This study compares microwave fixation of whole fetal specimens with conventional techniques performed at room temperature. All fetuses were obtained from the same pregnant rat; half of them were placed in neutral formalin for 15 min at room temperature, then irradiated for 2.5 min in a domestic microwave oven. The remaining fetuses were placed in neutral formalin at room temperature for 48 hr as a control. Both experimental and control groups were exposed to routine tissue processing for light microscopy and embedded in paraffin wax. Sections 5 microns thick were stained with hematoxylin and eosin. Our results showed that the microwave technique reduced the fixation time while providing thin sections that were equal to or better in quality than those in the control group.

Urethral reconstruction with autologous vein graft: an experimental study

There is no universally accepted material for urethral reconstruction. This study presents the results of segmental urethral replacement with a free graft of jugular vein in rabbits. Histological examination showed ingrowth of normal transitional epithelium into the venous endothelium. Retrograde urethrograms revealed an excellent result up to 300 days. Fistulas and infection occurred in 4/44 rabbits; these settled spontaneously. No structures or papillary hypertrophy were noted. Segmental urethral reconstruction with autologous vein graft is a simple technique with few complications and appears suitable for use in clinical cases.