Biomechanical performance of orthopedic gloves.

The purpose of this study was to compare the biomechanical performance of commercially available orthopedic gloves to that of a single surgical glove, as well as a double glove system. The orthopedic gloves were found to be thicker than the single surgical glove. This increased thickness of the orthopedic glove was associated with a greater resistance to glove puncture. The thickest orthopedic gloves also had reduced tactile sensitivity when compared to the single surgical glove. In addition, the glove donning forces and glove hydration rates varied considerably. These latter biomechanical performance parameters were not significantly related to glove thickness. The double glove systems tested in this study had similar performance characteristics in regard to many of the orthopedic gloves. The glove donning forces for the double glove systems were the lowest of the gloves tested. In addition, the double glove systems displayed the greatest resistance to glove hydration of the gloves tested. Their performance in the glove hydration tests and the force required to don the double glove systems were much more desirable than any of the orthopedic gloves. The results of this study indicate that the double glove systems may provide a desirable alternative to the use of the single orthopedic gloves.     

Failure of a new double glove hole detection system in the Emergency Department.

The purpose of this study was to evaluate the performance of a new double glove hole detection system in the Emergency Department. First, the frequency of holes in both gloves of the double glove hole detection system was determined using a watertight test method. Second, the frequency of glove puncture was determined first by searching for the optical color change that occurs with the ingress of fluid in the double glove hole detection system. These same gloves were then removed and also checked for holes by the watertight test method. After removal from the package, no holes were detected in the two gloves of the system using the watertight test method. In 50 consecutive patients, there was no color change in the inner glove indicating glove puncture. When these same gloves were then tested with the watertight test method, 14 of the 50 double glove hole detection systems failed; all 14 outer gloves were punctured, and three of the inner gloves had holes without demonstrable injury to the skin. This double glove hole detection system is not a reliable system to detect holes in relatively dry clinical settings because the ingress of fluid by capillary action between the gloves is necessary to cause a color change in the inner glove that signals the presence of a hole.     

Incidence of glove failure during orthopedic operations and the protective effect of double gloves

OBJECTIVE: To determine the usefulness of double gloves in protecting against the exposure of surgical team members' hands to blood. METHODOLOGY: Five-hundred-ninety-six gloves were studied during 71 orthopedic operations using the water-loading test (filling a glove with water and occluding its cuff tightly to identify leaking points). RESULTS: In all, 73 glove perforations occurred, but only nine resulted in exposure to blood (blood touching the skin). The incidence of glove perforation was 12% (73/596), and overall exposure (blood touching the skin) per operation was 13% (9/71). The latter would have been 87% (62/71) but for the use of double gloves. Sixteen percent of the perforations in double gloves were in the inner gloves, while 84% were in the outer gloves. Exposure of surgeons was reduced from 54% to 10%, first assistants from 27% to 3%, and second assistants from 7% to 0 (p < 0.02, df = 2) by double-gloving. Significantly more perforations occurred during operations on bone, compared with soft tissue operations, p < 0.0001, RR = 4 (95% CL 1.87-8.55). The most common sites of glove perforation were the index finger (47%), thumb, and the palm region: 14% each. More glove perforations occurred in nondominant hands. CONCLUSION: Double-gloving offers additional protection to surgeons and assistants by preventing hand exposure to blood intraoperatively.     

Biomechanical performance of latex and non-latex double-glove systems

The purpose of this study was to evaluate ten commercially available latex, powder-free surgical gloves and four commercially available non-latex, powder-free surgical gloves using standardized, reproducible biomechanical parameters that included glove thickness, puncture resistance, and glove donning force. For all gloves tested, with one exception (Neolontrade mark PF), puncture resistance increased for double-gloves as compared to single-gloves. In addition, single-glove thickness was not a reliable determinant of puncture resistance for either latex or non-latex gloves. For the latex gloves, the Ultrafree double and single-gloves exhibited the highest puncture resistance. The glove donning forces for the Biogeltrade mark M and Biogel Sensortrade mark single-gloves were the lowest. In contrast, the Biogel Revealtrade mark and Encoretrade mark Ultra-Thick exhibited the lowest double-glove donning forces. On the basis of these performance tests of latex gloves, the surgeon should consider the Biogel Reveal as well as the Ultrafree gloves for their latex double-glove system. For the non-latex gloves, the Pure Advantage Nitriletrade mark glove had the highest puncture resistance for one layer and two layers of glove material. The thin Pure Advantage Nitrile glove was the most resistant to glove puncture. The Pure Advantage Nitrile glove had low glove donning forces for both single-glove donning configurations and double-glove donning configurations. Consequently, we recommend the Pure Advantage Nitrile glove as the powder-free, non-latex, double-glove system.     

In vitro squeeze-flow phenomena at the instant of mechanical valve closure

Cavitation bubble formation associated with mechanical valve closure has been investigated in vitro, and the region of bubble formation has been correlated with large negative pressure transients. The region of cavitation bubbles forms in valve designs where leaflets interact with seat stops. It has been postulated that the fluid is squeezed between the leaflet and the seat stop and radially propelled at high velocities, resulting in further pressure reduction below the vapor pressure of fluid and initiating cavitation bubble formation. We conducted in vitro experiments to visualize and detect the presence of squeeze-flow phenomena associated with valve closure of mechanical heart valves. The closing dynamics were studied by simulating a single closing event of the leaflet with the valve mounted at the mitral position. Squeeze flow was detected at the instant of valve closure, when the valve leaflet interacts with the valve seat stop. The use of a high-speed video camera at 1000 frames per second with strobe light at 16000 pulses per second enabled the visualization of cavitation bubbles and its radial motion from the valve's seat stop due to the squeeze-flow effect. Vapor cavitation bubbles were observed to collapse within 0.5 ms after inception. In mechanical valves without seat stops in the major orifice region, bubbles of duration longer than that of the cavitation bubbles were observed. These microbubbles were present for 4 s before collapsing and are believed to be air bubbles whose presence in vivo has been detected with ultrasound imaging.     

Testing for viral penetration of non-latex surgical and examination gloves: a comparison of three methods

Currently, there are no international standards based on microbiological methodology for testing the ability of medical examination or surgical gloves to prevent the passage of viruses. Three protocols for the direct examination of the viral barrier properties of non-latex gloves were compared with 1080 gloves (270 gloves from each of two surgical brands and two medical examination brands). In two of the methods, gloves were filled with and suspended in a nutrient broth solution, and bacteriophage phiX174 was placed either inside or outside the glove, while the entire test vessel was agitated. Gloves tested using the third method were filled with a suspension of bacteriophage and allowed to rest in a vessel containing nutrient broth. Gloves were tested directly from the manufacturer's packaging, or after being punctured intentionally or subjected to a stress protocol. The passage of bacteriophage was detected with plaque assays. Significant differences in failure rates between glove brands were apparent only among gloves that had been subjected to the stress protocol. Overall, the two methods in which bacteriophage were placed inside the gloves provided more sensitivity than the method in which bacteriophage was spiked into broth outside the gloves. Thus the placement of bacteriophage inside test gloves (or the use of pressure across the glove barrier during testing), and the use of a standardised stress protocol, will improve significantly the ability of a glove test protocol to determine the relative quality of the barrier offered by medical examination and surgical gloves. Further research is needed to provide test methods that can incorporate reproducibly both the use of bacteriophage and simulated glove use in an industrial quality control setting.     

Air filtering capacity of an integrated cardiopulmonary bypass unit

To limit the morbidity of cardiopulmonary bypass (CPB), a new concept of integrating pumping, oxygenation, and air removal into a single unit has been developed (CardioVention Inc., Santa Clara, CA). The air filtration capacity of this system was tested. Three calves (73.2 +/- 2 kg) were connected to the integrated system by jugular and carotid cannulation. The integrated unit was challenged with injections of boluses of air of 5, 10, and 20 ml, three times each, and for a blood flow of 3 L/min and 5 L/min, respectively. The bubble count and size were recorded downstream of the unit with a Doppler ultrasound. At 3 L/min, bubbles were detected after injections of 20 ml only (n = 7 for the nine boluses). At 5 L/min, 1 bubble was detected with the nine injections of 5 ml, 14 bubbles were detected with nine injections of 10 ml, and 25 bubbles were detected with nine injections of 20 ml. No bubble exceeded 40 microm in diameter as determined by the Doppler ultrasound. The air filtering capacity of the CardioVention system is excellent both in terms of bubble count and of size after injection of large boluses of air. Its integrated concept offers a simplification of the circuit with fewer devices and connections, which further reduces the risk of accidental air introduction.     

Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats

Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture while at 285 kPa or following immediate recompression to either 285 or 405 kPa, breathing 80:20 and 50:50 heliox mixtures. During the isobaric shifts, some bubbles in adipose tissue grew marginally for 10–30 min, subsequently they shrank and disappeared at a rate similar to or faster than during air breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent shrinkage of all air bubbles, until they disappeared from view. Deep tissue isobaric counterdiffusion may cause some air bubbles to grow transiently in adipose tissue. The effect is marginal and of no clinical consequence. Bubble disappearance rate is faster with heliox breathing mixtures as compared to air. We see no reason for reservations in the use of heliox breathing during treatment of air-diving-induced decompression sickness.     

Frequency of glove puncture in the post mortem room.

The post mortem room is a potential source of danger from contamination caused by glove punctures. The objective of this study was to assess the incidence of hand injury and hand contamination during post mortem examinations. A prospective study of injury and glove puncture rate was conducted during post mortem examinations performed in 1990 on adults in Northwick Park Hospital mortuary. Four pathologists and two assistants performed a total of 44 post mortem examinations on adults. All participants completed a questionnaire after each examination, recording the total number of gloves used and the number of hand injuries and glove perforations sustained. Just over 8.3% of gloves were punctured; 31.8% of these punctures went unnoticed. Evisceration was the procedure most likely to result in hand contamination. The study highlights a significant risk which could be reduced by more care, frequent glove changes, and hand washing during post mortem examinations. In particular, gloves should be changed and hand washed when evisceration has been completed.     

Extractable latex allergens in airborne glove powder and in cut glove pieces

BACKGROUND: Quantification of natural rubber latex (NRL) allergens of NRL glove extracts has been reported in several studies. Similarly, immunoassay studies reporting the level of NRL aeroallergens in air samples have been published. When studying the NRL allergens of gloves, however, little attention has been focused on identifying the relationship between extractable NRL allergens of medical gloves and NRL aeroallergens in indoor air. OBJECTIVE: In an experimental study we analysed NRL aeroallergens of medical gloves in joint relation to total airborne dust concentration and NRL allergen concentration in gloves. METHODS: NRL aeroallergen level was measured using a chamber setting with 18 lots of powdered medical gloves. In each setting 10 pairs of powdered NRL gloves were swinging in an unventilated chamber (9 m3). Air samples were collected using airflow through Millipore filters (pore size 0.8 microm). The filters were weighed before and after the experiment, and total airborne dust concentration in the chamber was calculated. The filter samples were then extracted and the NRL allergen level measured by IgE ELISA-inhibition assay. Furthermore, cut NRL gloves were extracted and analysed by the same method. Finally, levels of two major NRL allergens, Hev b1 and Hev b 6.02, were measured in three selected NRL glove brands. RESULTS: The NRL aeroallergen level in the chamber air ranged from < 0.9 to 2.9 allergen units (AU)/m3. The total airborne dust concentration in the chamber air remained low with all lots of gloves measured (range < 20 to 80 microg/m3). The NRL allergen level in cut glove extracts varied over 100-fold (< 10 to 1050 AU/mL). Statistically significant correlation between aeroallergen concentration and airborne dust (r = 0.8, P = 0.0015) concentration was found. Moreover, significant correlation between aeroallergen levels and allergen content of cut glove pieces was observed (r = 0.59, P < 0.05). Hev b 1 levels varied from 9 to 25 ng/mL and the levels of Hev b 6.02 from 1720 to 14460 ng/mL in the glove extracts. In the extracts from airborne dust samples, Hev b 6.02 content varied from 61 to 183 ng/m3, whereas Hev b 1 levels were very low (0.4 to 3 ng/m3). CONCLUSION: An elevated NRL aeroallergen level is rather related to a high level of airborne glove powder than to a high concentration of extractable NRL allergen in medical gloves.     

Prevention of air bubble formation in a microfluidic perfusion cell culture system using a microscale bubble trap

Formation of air bubbles is a serious obstacle to a successful operation of a long-term microfluidic systems using cell culture. We developed a microscale bubble trap that can be integrated with a microfluidic device to prevent air bubbles from entering the device. It consists of two PDMS (polydimethyldisiloxane) layers, a top layer providing barriers for blocking bubbles and a bottom layer providing alternative fluidic paths. Rather than relying solely on the buoyancy of air bubbles, bubbles are physically trapped and prevented from entering a microfluidic device. Two different modes of a bubble trap were fabricated, an independent module that is connected to the main microfluidic system by tubes, and a bubble trap integrated with a main system. The bubble trap was tested for the efficiency of bubble capture, and for potential effects a bubble trap may have on fluid flow pattern. The bubble trap was able to efficiently trap air bubbles of up to 10 μl volume, and the presence of captured air bubbles did not cause alterations in the flow pattern. The performance of the bubble trap in a long-term cell culture with medium recirculation was examined by culturing a hepatoma cell line in a microfluidic cell culture device. This bubble trap can be useful for enhancing the consistency of microfluidic perfusion cell culture operation.     

Cotton fluffs as latex allergen carriers in a glove factory

BACKGROUND: Latex allergens released from gloves and bound to airborne cornstarch powder have been shown to cause respiratory allergy in health care workers. OBJECTIVE: Cornstarch from powdered latex gloves is a well-known carrier of airborne allergens. It should be investigated whether cotton fluffs used to lubricate household and industrial gloves also function as airborne carriers for latex allergens. METHODS: Latex gloves, cotton fluffs with or without latex glove contact, dipping water from the glove cooling tank, a dust sample from the floor, and 10 samples from area dust samplers were analyzed for their allergen content by using a CAP inhibition method. Furthermore, 84% (119/142) of the working group participated in a cross-sectional study involving a questionnaire and measurement of latex-specific IgE by means of CAP inhibition. RESULTS: Latex gloves, area dust samples from latex glove production sites, and the floor dust sample contained high concentrations of latex allergens. Cotton fluffs were free of allergens before being in contact with gloves but showed considerable allergen concentrations after their removal from gloves. The dipping water of the cooling tank also contained latex allergens. Of the examined employees, 12.6% had IgE-mediated sensitization, and a third of the sensitized subjects (ie, 4% of the total group) reported work-related hypersensitivity reactions. CONCLUSIONS: Cotton fluffs bind latex allergens and behave like cornstarch as airborne allergen carriers causing conjunctivitis and allergic respiratory disorders.     

颅脑减速碰撞中脑组织空化效应的模拟研究

目的:构建一种新的方法用于再现颅脑减速撞击过程中对冲部位的空化效应.方法:制作含微气泡的透明颅脑物理模型,并将其安放在竖式颅脑减速撞击移动平台上.在高强度灯光的照明环境中,将移动平台以40 cm的高度自由下落而撞击固定台面,同时采用高速摄像记录减速撞击的整个过程.之后用序列图片分析软件计算微气泡的体积与平均压力的变化,研究碰撞过程中脑组织的空化效应.结果:位于撞击对侧的微气泡在撞击过程中其体积明显增大,位于撞击侧的微气泡在撞击过程中其体积减小,位于中性点的微气泡在撞击过程中其体积增减不明显.结论:该实验结果表明颅脑对冲部位出现了负压,存在空化现象.清晰直观地再现了颅脑减速撞击过程中对冲部位的空化效应.有助于在一定程度上较好地认识颅脑减速撞击过程中脑组织内动态应力的分布特点,为阐明交通事故伤中较为常见的颅脑"对冲伤"的力学发生机制提供一定的方法和实验基础.同时该方法对于研究颅脑减速撞击损伤的致伤机理及其诊断和防护具有重要意义.     

Cow's milk casein, a hidden allergen in natural rubber latex gloves.

BACKGROUND: We have previously noted that one natural rubber latex (NRL) glove brand used for skin prick testing in the diagnosis of NRL allergy contained cow's milk casein. OBJECTIVE: We sought to examine whether other commonly marketed NRL glove brands contain cow's milk casein. METHODS: The casein content of 30 NRL glove extracts (1:5 wt/vol) was measured by RAST inhibition and by rocket immunoelectrophoresis and rocket radioimmunoelectrophoresis by using casein-specific rabbit antiserum, a serum pool from patients with cow's milk allergy, and radiolabeled anti-human IgE. The NRL allergen content was measured by ELISA inhibition. RESULTS: The casein content of the glove used in NRL allergy screening (Triflex, Baxter) was rather high (ie, about 400 microgram/g of glove). Its total protein content was 1000 microgram/g of glove. Rocket radioimmunoelectrophoresis detected distinct amounts of casein in 8, minimal amounts in 7, and no casein in the remaining 15 NRL glove brands. CONCLUSIONS: Several brands of NRL gloves were found to contain casein, implying that extracts prepared from such gloves can cause false-positive skin prick test reactions when diagnosing NRL allergy. The use of casein as a stabilizer in glove manufacture without appropriate labeling should be stopped because it can also cause contact urticaria syndrome in individuals with cow's milk allergy.     

Biomechanical performance of examination gloves.

The purpose of this study was to compare the biomechanical performance of new powder-free commercially available synthetic examination gloves to that of commercially available powder-free latex examination gloves. The synthetic gloves were significantly thinner than the latex gloves. Despite the decreased thickness, all three nitrile gloves, as well as the polyvinyl chloride glove, exhibited a greater resistance to glove puncture. The glove donning forces varied considerably among all gloves, and wet donning forces were greater than dry donning forces. Under dry conditions, the donning forces for the synthetic gloves were less than or equal to the forces for the latex gloves. Because of their increased puncture resistance and similar donning forces, synthetic gloves are a safe alternative to latex examination gloves.     

Haptic stabilization of posture: changes in arm proprioception and cutaneous feedback for different arm orientations

Postural sway during quiet stance is attenuated by actively maintained contact of the index finger with a stationary surface, even if the level of applied force (<1 N) cannot provide mechanical stabilization. In this situation, changes in force level at the fingertip lead changes in center of foot pressure by approximately 250 ms. These and related findings indicate that stimulation of the fingertip combined with proprioceptive information about the hand and arm can serve as an active sensor of body position relative to the point of contact. A geometric analysis of the relationship between hand and torso displacement during body sway led to the prediction that arm and hand proprioceptive and finger somatosensory information about body sway would be maximized with finger contact in the plane of body sway. Therefore, the most postural stabilization should be possible with such contact. To test this analysis, subjects touched a laterally versus anteriorly placed surface while in each of two stances: the heel-to-toe tandem Romberg stance that reduces medial-lateral stability and the heel-to-heel, toes-outward, knees-bent, "duck stance" that reduces fore-aft stability. Postural sway was always least with finger contact in the unstable plane: for the tandem stance, lateral fingertip contact was significantly more effective than frontal contact, and, for the duck stance, frontal contact was more effective than lateral fingertip contact. Force changes at the fingertip led changes in center of pressure of the feet by approximately 250 ms for both fingertip contact locations for both test stances. These results support the geometric analysis, which showed that 1) arm joint angles change by the largest amount when fingertip contact is maintained in the plane of greatest sway, and 2) the somatosensory cues at the fingertip provide both direction and amplitude information about sway when the finger is contacting a surface in the unstable plane.     

Anaphylaxis produced by rubber glove contact. Case reports and immunological identification of the antigens involved

A study was carried out on six subjects suffering from anaphylactic reactions including asthma, rhinoconjunctivitis, contact urticaria and hypotension following contact with rubber gloves. All of them showed skin sensitivity and serum specific IgE to various preparations of natural latex, and not to other chemicals used in glove manufacturing. Immunoblotting techniques demonstrated that at least four soluble polypeptides from natural latex had the ability to bind specific human IgE. The results suggested that natural latex proteins present in rubber gloves can cause severe specific hypersensitivity reactions.     

The scientific basis of surgical glove selection in an in vitro fertilization laboratory.

Mouse embryos and human sperm are used as quality control bioassays in human in vitro fertilization (IVF) laboratories. These two models can reveal the cytotoxicty of items commonly used in IVF, such as surgical gloves. The literature published in this area points to the cytotoxicity of both glove powders and glove products.     

Aerobic exercise before diving reduces venous gas bubble formation in humans

We have previously shown in a rat model that a single bout of high-intensity aerobic exercise 20h before a simulated dive reduces bubble formation and after the dive protects from lethal decompression sickness. The present study investigated the importance of these findings in man. Twelve healthy male divers were compressed in a hyperbaric chamber to 280kPa at a rate of 100kPamin⁻¹ breathing air and remaining at pressure for 80min. The ascent rate was 9mmin⁻¹ with a 7min stop at 130kPa. Each diver underwent two randomly assigned simulated dives, with or without preceding exercise. A single interval exercise performed 24h before the dive consisted of treadmill running at 90% of maximum heart rate for 3min, followed by exercise at 50% of maximum heart rate for 2min; this was repeated eight times for a total exercise period of 40min. Venous gas bubbles were monitored with an ultrasonic scanner every 20min for 80min after reaching surface pressure. The study demonstrated that a single bout of strenuous exercise 24h before a dive to 18 m of seawater significantly reduced the average number of bubbles in the pulmonary artery from 0.98 to 0.22 bubbles cm⁻²  ( P = 0.006)  compared to dives without preceding exercise. The maximum bubble grade was decreased from 3 to 1.5  ( P = 0.002)  by pre-dive exercise, thereby increasing safety. This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness.     

Evaluation of anti-vibration effectiveness of glove materials using an animal model

Gloves with anti-vibration features are increasingly used to reduce impact vibrations or shocks transmitted to the hands of power tool operators. Selection and evaluation of the glove materials are important steps in the designs of such gloves. In the current study, we proposed an approach to objectively evaluate the effectiveness of the glove materials using a rat-tail impact model. As a critical part of a systematic investigation, we examined the vibration reduction characteristics of typical resilient glove materials (air bladders and viscoelastic gels) and the impact vibrations transmitted to the rat tail. A special test platform that mimics impact tool vibrations was constructed and used in the experiment. A scanning laser vibrometer was used to measure the vibration at points across the platform surface under several different test conditions. The peak acceleration was found to be greatly attenuated by the glove materials, especially by using strips from a gel-filled glove. The rat tail was found to effectively absorb the high-frequency vibration. However, the glove materials and the rat tail did not reduce the frequency-weighted acceleration. The implications of the experimental results are discussed.