Oct. 21, 2024
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Disposable gloves are essential in various industries, including healthcare, food service, and manufacturing. Ensuring their quality is paramount to protecting users from contamination and ensuring safety. One critical aspect of quality assurance for disposable gloves is testing for side leakage. This article explores the importance of side leakage machines in the quality testing process for disposable gloves and other methods used to ensure their reliability.
Side leakage machines play a crucial role in testing disposable gloves for defects that could compromise their integrity. These machines are designed to detect any leaks or weak points along the seams and edges of gloves, which are common areas for defects. By simulating real-world conditions, side leakage machines ensure that each glove can withstand typical usage without failing.
Side leakage machines typically use air or water to test gloves. The gloves are filled with air or water, and the machine then checks for any signs of leakage. Here&#;s a breakdown of the process:
1. Inflation Method: The glove is filled with air at a specified pressure. The machine monitors the glove for any decrease in pressure, which would indicate a leak.
2. Water Leakage Test: The glove is filled with water and then examined for any signs of water escaping through the material or seams. This method is highly effective in detecting even the smallest leaks.
Both methods provide a thorough examination of the glove&#;s integrity, ensuring that any defective products are identified and discarded before reaching consumers.
While side leakage machines are vital, other tests are also conducted to ensure the overall quality of disposable gloves. These tests help verify the gloves' durability, elasticity, and resistance to various conditions.
Visual Inspection
Before any mechanical testing, gloves undergo a visual inspection to identify obvious defects such as holes, tears, or incomplete seams. This initial check helps to eliminate any significantly defective gloves from the batch.
Tensile Strength Test
This test measures the glove&#;s ability to stretch without breaking. Gloves are pulled apart at a constant rate until they break. The tensile strength and elongation at break are recorded to ensure the gloves meet the required standards for durability and flexibility.
Puncture Resistance Test
Gloves must also be resistant to punctures, which is crucial for protecting against sharp objects. In this test, a standardized needle is used to puncture the glove, and the force required to penetrate the material is measured. High puncture resistance indicates a higher level of protection.
Chemical Resistance Test
For gloves used in environments where they might come into contact with chemicals, it&#;s essential to test their resistance to various substances. Gloves are exposed to different chemicals, and their degradation is monitored over time. This test ensures that the gloves can provide adequate protection in chemical handling situations.
Quality testing of disposable gloves is crucial for several reasons:
- User Safety: Ensuring gloves are free from defects protects users from exposure to harmful substances and contaminants.
- Compliance: Meeting industry standards and regulations is necessary for legal and operational compliance.
- Customer Trust: High-quality gloves build trust with customers, leading to brand loyalty and repeat business.
In conclusion, the use of side leakage machines and other quality testing methods is essential to ensure the reliability and safety of disposable gloves. These tests help identify defects and weaknesses, ensuring that only high-quality gloves reach the market. For more information on our testing procedures or to inquire about our range of disposable gloves, feel free to contact us. If you are looking for a reliable supplier of high-quality disposable gloves, we are here to meet your needs.
There is moderate&#;quality evidence that double gloving compared to single gloving during surgery reduces perforations and blood stains on the skin, indicating a decrease in percutaneous exposure incidents. There is low&#;quality evidence that triple gloving and the use of special gloves can further reduce the risk of glove perforations compared to double gloving with normal material gloves. The preventive effect of double gloves on percutaneous exposure incidents in surgery does not need further research. Further studies are needed to evaluate the effectiveness and cost&#;effectiveness of special material gloves and triple gloves, and of gloves in other occupational groups.
There was moderate to low&#;quality evidence in two studies that an indicator system does not reduce the total number of perforations during an operation even though it reduces the number of perforations per glove used.
We found low&#;quality evidence in one small study that the use of three gloves compared to two gloves reduces the risk of perforation further (RR 0.03, 95% CI 0.00 to 0.52). There was similar low&#;quality evidence that the use of one fabric glove over one normal glove reduces perforations compared to two normal gloves (RR 0.24, 95% CI 0.06 to 0.93). There was moderate&#;quality evidence that this effect was similar for the use of one special material glove between two normal material gloves. Thicker gloves did not perform better than thinner gloves.
We found moderate&#;quality evidence that double gloves compared to single gloves reduce the risk of glove perforation (rate ratio (RR) 0.29, 95% confidence interval (CI) 0.23 to 0.37) and the risk of blood stains on the skin (RR 0.35, 95% CI 0.17 to 0.70). Two studies with a high risk of bias also reported the effect of double compared to single gloves on needlestick injuries (RR 0.58, 95% CI 0.21 to 1.62).
We found 34 RCTs that included person&#;operations as participating units and reported on 46 intervention&#;control group comparisons. We grouped interventions as follows: increased layers of standard gloves, gloves manufactured with special protective materials or thicker gloves, and gloves with puncture indicator systems. Indicator gloves show a coloured spot when they are perforated. Participants were surgeons in all studies and they used at least one pair of standard gloves as the control intervention. Twenty&#;seven studies also included other surgical staff (e.g. nurses). All but one study used perforations in gloves as an indication of exposure. The median control group rate was 18.5 perforations per 100 person&#;operations. Seven studies reported blood stains on the skin and two studies reported self reported needlestick injuries. Six studies reported dexterity as visual analogue scale scores for the comparison double versus single gloves, 13 studies reported outer glove perforations. We judged the included studies to have a moderate to high risk of bias.
Healthcare workers are at risk of acquiring viral diseases such as hepatitis B, hepatitis C and HIV through exposure to contaminated blood and body fluids at work. Most often infection occurs when a healthcare worker inadvertently punctures the skin of their hand with a sharp implement that has been used in the treatment of an infected patient, thus bringing the patient's blood into contact with their own. Such occurrences are commonly known as percutaneous exposure incidents.
Surgeons and surgical staff can reduce their risk of contracting a serious viral infection by wearing two pairs of gloves instead of one pair of gloves. The use of three glove layers or gloves made from special material probably reduces the risk further but these need better evaluation. We need further studies to evaluate whether gloves have a similar preventive effect in other healthcare professionals outside the operating theatre.
Five low&#;quality studies showed that the number of perforations was similar for thicker and thinner gloves. In two low&#;quality studies, the use of one pair of fabric gloves over one pair of normal gloves reduced perforations compared to two pairs of normal gloves. This was similar for gloves made from special material such as fabric or steel, used in between normal gloves.
In 12 studies, two pairs of gloves reduced the number of perforations in gloves by 71% compared to the use of one pair of gloves. In three studies, two pairs of gloves reduced blood stains on the skin by 65%. The reduction in self reported needlestick injuries was less clear.
Healthcare workers can hurt themselves accidentally with needles or sharp instruments that have been used in patient care. This carries a small risk that the healthcare worker becomes infected with a viral disease such as hepatitis or HIV. Therefore it is important to prevent blood contact to prevent infection. We evaluated whether the use of gloves, more than one layer of gloves or special gloves can prevent needles or sharp instruments from piercing the skin. Up until June , we found 34 studies that evaluated operations. There were no studies in non&#;surgical staff.
There are several strategies available to reduce PEIs among healthcare workers and these are widely used. It is therefore important to know whether these preventive interventions are effective. Retrospective studies indicate that PEIs can be reduced by more than 50% by behavioural interventions, either education or the adoption of new techniques ( Bryce ; Castella ). The use of safety devices may also have a significant effect ( Bryce ; Castella ; Waclawski ). Even though the protective effect of double gloving has been shown for a long time in individual studies, it has been reported that single gloving still occurs (see also Cicconi and Haines ). However, the use of single gloves among healthcare workers is inconsistent and may be influenced by several factors including risk perception, healthcare culture and the availability and accessibility of supplies ( Fadeyi ; Kinlin ; Timilshina ). Glove use should be emphasised as a key element of multimodal sharps injury reduction programmes. A systematic review might help in the better implementation of an effective intervention. Extra gloves would also help to reduce transmission of infections from healthcare workers to patients. This topic has been studied in another Cochrane Review ( Tanner ) and the authors found two trials that reported fewer patient infections with double gloving. Needlestick injuries sustained by surgical staff were, however, not a primary outcome in that review. Our review is one of a group of Cochrane Reviews that address interventions to prevent PEIs: one on blunt needles by Parantainen , one on safe devices by Lavoie and another on education and training, which is ongoing.
The effectiveness of intact latex gloves as protection from HIV, for instance, has been shown in mechanical tests in the laboratory ( Dalgleish ). Wearing multiple gloves (two or more pairs of gloves) is thought to provide increased resistance to needle penetration and thus protection against the transmission of body fluids ( Edlich ). Special materials, such as gloves made from stainless steel wire weave, are expected to have a similar effect, as demonstrated by mechanical puncture tests with a needle penetration machine ( Diaz&#;Buxo ; Leslie ; Manson ; Mansouri ). Lefebvre demonstrated that double gloving significantly decreases the transmission of aqueous contaminant with cutting surgery needles as compared to a single glove layer. Finally, an indicator system attached to gloves might also decrease exposure to blood because it warns the user about glove punctures. Even though this would not prevent needlestick injuries as such, it could influence the person's behaviour in performing the task more safely and thus have a preventive effect.
There are several types of interventions to prevent infection from PEI. For hepatitis B, vaccination has been successful ( Chen ), but vaccination is not yet possible for hepatitis C or HIV ( Mast ). Exposure reduction therefore remains the main preventive strategy. In general, there are several strategies for reducing or eliminating exposure, such as elimination of hazards at the source (for example, the elimination of unnecessary injections) or along the path (for example, safety medical devices or workplace practices, use of personal protective equipment, etc.) ( Ellenbecker ; Roelofs ). The intervention examined in this Cochrane review, the use of gloves, is in the category of personal protective equipment.
The risk of acquiring an infection is proportional to the prevalence of the infections in the patient population. Thus, in areas where hepatitis B, hepatitis C and HIV are highly prevalent, such as in certain countries in Africa, Asia and Eastern Europe, the risks are much higher than in Northern and Western Europe, Australia or in North America ( Centers for Disease Control ; Shepard ). This situation has a significant impact on the health of workers and also on the healthcare system as a whole. The transmission of occupational blood&#;borne infectious diseases leads to absenteeism, morbidity and, in some cases, mortality among healthcare workers. This leads to a reduction in the healthcare workforce and consequently affects patients&#; quality of care and safety. The risk of acquiring an infectious disease at work means that healthcare workers may also suffer from psychological stress, which affects both their work and personal life ( Fisman ; Sohn ). There is also an economic burden imposed on hospitals due to managing occupational exposure to blood&#;borne diseases, such as costs related to blood tests, treatment, outpatient visits and lost working hours.
Healthcare workers are at risk of acquiring infectious diseases through exposure at work. Exposure to blood or bodily fluids from infected patients can lead to infection with hepatitis B, hepatitis C and human immunodeficiency virus (HIV), among other pathogens. These are serious viral infections that may cause a chronic disease process or initiate cancer and eventually lead to death. According to Pruss&#;Ustun et al, 16,000 hepatitis C, 66,000 hepatitis B and HIV infections may have occurred worldwide among healthcare workers in the year due to occupational exposure to blood and bodily fluids ( Pruss&#;Ustun ). The World Health Organization (WHO) reports that two million healthcare workers across the world experience percutaneous exposure to infectious diseases each year ( WHO ). In Europe it is estimated that there are more than one million needlestick injuries annually ( European Biosafety Network ). A European Union directive on prevention of sharp injuries in the hospital and healthcare sector was agreed upon in , and member states were bound to implement the directive into their national legislation by May .
We conducted two sensitivity analyses to find out if risk of bias led to changes in the findings. We first re&#;analysed the results including only studies with a low risk of bias. In a second re&#;analysis we included all studies with a low and unknown risk of bias.
We re&#;analysed the data to determine whether there was a difference in effect in studies with high exposure in the control group. We also re&#;analysed subgroups from low and middle&#;income countries for the year of study publication since limited resources create special challenges for preventive care, as reported by World Bank . We also regrouped studies that were carried out in countries with a high HIV or hepatitis C prevalence among adults, as reported by the Centers for Disease Control and Prevention ( Centers for Disease Control ).
Finally, we used the GRADE approach to assess the quality of the evidence per comparison and per outcome, as described in the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins ). Starting from an assumed level of high quality, we reduced the quality of the evidence by one or more levels if there were one or more limitations in the following domains: risk of bias, consistency, directness of the evidence, precision of the pooled estimate and the possibility of publication bias. Thus, we rated the level of evidence as high, moderate, low or very low depending on the number of limitations. For the most important comparisons and outcomes, we used the program GRADEpro to generate 'Summary of findings' tables ( GRADEpro ).
For studies with multiple study arms that belong to the same comparison, we divided the number of events and participants equally over the study arms to prevent double counting of study participants in the meta&#;analysis (e.g. Analysis 7.1 ; Laine b DI ).
We pooled studies with sufficient data, which we judged to be clinically and statistically homogeneous, with RevMan 5 software ( RevMan ). Where studies were statistically heterogeneous, we used a random&#;effects model; otherwise we used a fixed&#;effect model.
We assessed statistical heterogeneity by means of the I 2 statistic. We used the values of < 40%, between 30% and 60%, between 50% and 90%, and > 75% as indicating not important, moderate, substantial and considerable heterogeneity, respectively, as proposed in the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins ).
We divided outcomes into inner, outer and matched glove perforations, reported needlestick injuries, observable blood stains on the hands and dexterity reported on a VAS scale. We judged studies falling within these categories to be conceptually similar and sufficiently homogeneous to be combined in a meta&#;analysis.
We defined studies as clinically homogeneous when they had similar populations, interventions and outcomes measured at the same follow&#;up point. We judged interventions to be sufficiently homogeneous when they fit into one of the categories defined in Types of interventions . We regarded all healthcare professionals as sufficiently similar to assume a similar preventive effect from glove interventions. We also considered studies similar for participants with a high and a low exposure level.
We contacted the authors of seven included studies but did not receive an answer or authors could not provide us with the additional information needed for the meta&#;analysis. We could calculate the number of operations for three studies ( Carter ; Chua ; Liew Single ) and the number of persons participating in the operation for three other studies ( Laine b 2R ; Laine b DI ; Naver ) from the data presented in the article. We based our calculation on the assumption that only one pair of gloves was collected per person per procedure.
We intended to calculate the design effect for studies that employed a cluster&#;randomised design but did not make an allowance for the design effect. In studies where the operators were randomised or where the unit of randomisation was the operation or the patient and where there was only one surgeon, we assumed that there was no unit of analysis issue. In studies where the unit of analysis was the patient or operation and where there was more than one person who could sustain needlestick injuries in one operation, the outcomes could be clustered at the operator level. To avoid these issues, we calculated all outcomes per surgeon and per operation. We called this unit of analysis a surgeon&#;operation to indicate that this was the risk for one surgeon performing one operation.
We treated the results of all trials as being dichotomous and used rate ratios (RR) rather than odds ratios, because of the high prevalence of most outcomes. Some studies reported rates that were larger than one per unit because needlestick injuries or glove perforations can be sustained more than once. To address this issue, we calculated the natural logarithm (ln) of the RRs and their standard errors from the number of glove perforations and the number of surgeon&#;operations in an Excel spreadsheet, as recommended by the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins ). We used the natural log of the rate ratios and their standard errors as input in RevMan where we combined them using the generic inverse variance method. We provide the raw data for all studies in additional tables ( Table 2 ; Table 3 ; Table 4 ).
Authors reported the outcome of their studies in many different ways. We assumed that the most valid estimate of the risk of exposure for healthcare personnel was provided by the number of holes in gloves used by one person during one operation. It would have been more precise if 'operation' could have been defined as 'the number of hours engaged in an operation of average difficulty', comparable to a number of person&#;years at risk, but the data were not sufficient to calculate this.
To rate the overall risk of bias in studies, we used random sequence generation, allocation concealment and blinding of the outcome assessor as the most important domains. We rated studies that had a high risk of bias in one of these three items as having a high risk of bias. We rated studies with low risk of bias in all three items as having a low risk of bias.
For the assessment of risk of bias in studies, we used the 'Risk of bias' tool as provided in RevMan 5 ( RevMan ). We used the items on randomisation, allocation concealment, blinding of participants and outcome assessors, incomplete outcome data and selective outcome reporting, as described in the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins ).
Authors worked independently in pairs to extract data from the included studies into a form (AS and JV, M&#;CL and MP, CM and SI). The form included the essential characteristics of the study, participants, interventions, outcomes and results. We also noted any adverse events and the sponsorship of the study. The two pairs of authors (AS and JV, M&#;CL and MP, CM and SI) independently assessed the risk of bias of each study, using consensus when disagreements occurred. The pairs consulted a third author when disagreements persisted. We did not mask trial names because we did not believe that this would have increased validity.
Using the inclusion and exclusion criteria, authors worked independently in pairs (AS and JV, M&#;CL and MP) to screen the identified titles and abstracts of the references that were identified by the search strategy for potential studies. We obtained the full texts of those references that appeared to meet the inclusion criteria. We did not blind the full&#;text articles because we felt that this would not increase validity. We resolved disagreements between pairs by consensus. The pairs consulted a third author when disagreements persisted.
For the updated search we simplified the original search and used only a filter for randomised studies. We searched the same databases up until June , except for LILACS, because the initial search did not reveal any studies ( Appendix 2 ).
We used the strategy to search CENTRAL, MEDLINE, EMBASE, NHSEED, Science Citation Index Expanded, CINAHL, OSH&#;update (NIOSHTIC and CISDOC), LILACS and PsycINFO from the earliest record to September . In addition, we searched the databases of WHO, the UK National Health Service (NHS) and the International Healthcare Worker Safety Center until ( Appendix 1 ).
For the original search we first applied search terms for percutaneous exposure incident (PEI). We then combined these terms for PEI with the recommended search strings for randomised trials ( Robinson ) and for non&#;randomised studies ( Verbeek ).
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The search until September was part of a larger search for all interventions to prevent percutaneous exposure incidents (PEIs) in healthcare personnel. For interventions that are difficult to randomise we then also included non&#;randomised studies. After the division of the original review into four separate reviews in , we used an updated search strategy that was restricted to randomised glove studies only.
We used dexterity as a secondary outcome. We used the ratio of the number of perforations in the most outer gloves as an indication of loss of dexterity when wearing two glove layers compared to one glove layer. This is based on the assumption that a loss of dexterity as a result of double gloving would lead to a higher number of perforations in the outer gloves, whereas the inner gloves could still protect against skin perforation. In addition, we took visual analogue scales (VAS) as indicators of loss of dexterity.
Exposure of healthcare workers to potentially contaminated bodily fluids, including blood, was our primary outcome measure. Exposure could be either needlestick injury, sharps injury, blood stains inside the gloves or on the skin, or glove perforations. We considered all reports of such exposure as valid measures of the outcome, including self reports, reports by the employer or empirical observations of blood stains by researchers.
Participants are healthcare workers, who are all persons professionally involved in providing health care to patients. We decided that at least 75% of the participants needed to fulfil this criterion.
In a third subgroup analysis for the same comparison, we grouped studies according to the exposure in the control groups. We labelled studies with more than 0.2 perforations per person&#;operation in the control group as high&#;exposure studies (n = 4). For double gloving the effect in the high&#;exposure studies was slightly better (RR 0.27, 95% CI 0.19 to 0.39) than in studies with lower exposure rates (RR 0.31, 95% CI 0.22 to 0.43) ( Analysis 10.1 ). The subgroup difference was non&#;significant (P value = 0.66).
In a second analysis for the same comparison, we grouped studies from low and middle&#;income countries and studies from high&#;income countries in different subgroups. For double gloving the effect for high&#;income countries was slightly better, with a rate ratio of 0.23 (95% CI 0.16 to 0.34) compared to 0.34 (95% CI 0.24 to 0.47) for low and middle&#;income countries ( Analysis 9.1 ). The difference between subgroups was non&#;significant (P value = 0.15).
For the main comparison, which had clear significant results and included most of the studies ( Analysis 1.1 ), we grouped studies from countries with a high HIV or hepatitis C prevalence in one subgroup. Ten of 12 studies belonged to the category with a HIV prevalence of more than 1% or a hepatitis C prevalence of more than 2%. For double gloving, the effect in the studies from the high prevalence countries was slightly better (RR 0.28, 95% CI 0.22 to 0.37) than in countries with a lower prevalence (RR 0.38, 95% CI 0.15 to 0.96) ( Analysis 8.1 ). The subgroup difference was non&#;significant (P value = 0.54).
We also carried out a sensitivity analysis in comparisons with high heterogeneity, leaving out studies with a high risk of bias. For two studies comparing thicker with thinner gloves the rate ratio of 0.75 (95% CI 0.55 to 1.02) remained non&#;significant and almost the same as 0.63 (95% CI 0.37 to 1.08), however the heterogeneity dropped from 67% to 0% (I² statistic).
For two studies without a high risk or bias triple special versus double normal gloves yielded a rate ratio of 0.25 (95% 0.10 to 0.65), which is similar to 0.24 (95% CI 0.13 to 0.45), but the heterogeneity measured with the I² statistic increased from 33% to 56%.
We left out one study with a high risk of bias from the meta&#;analysis that compared double special with double normal gloves. The pooled rate ratio for the two subgroups using fabric gloves increased significantly from 0.24 (95% CI 0.06 to 0.93) to 0.13 (95% CI 0.06 to 0.29) and the heterogeneity dropped from 78% to 0% (I² statistic).
For seven studies without a high risk of bias double gloving versus single gloving yielded a rate ratio of 0.33 (95% CI 0.21 to 0.51) which is almost exactly the same as the overall result of 0.29 (95% CI 0.23 to 0.37). Heterogeneity remained the same (I² = 0%).
We carried out a sensitivity analysis for the comparisons that yielded positive results by leaving out all studies that we judged as being at high risk of bias for at least one of the items: random sequence generation, allocation concealment or blinding of outcome assessor. A sensitivity analysis including only low&#;risk studies was not possible, as only one study had a low risk of bias for all three items ( Tanner ).
There was one study that reported the loss of dexterity, rated with VAS scores for double gloves with indicator systems versus double gloves without the system, but sensitivity and dexterity were still rated as adequate for both gloving types ( Analysis 7.4 ).
Laine did not provide sufficient information to be included in the meta&#;analysis. For the first gloves the authors reported no difference in the number of perforations to the inner glove in intervention and double standard gloves groups (six perforations in both groups) but a big difference in inner glove perforations in the intervention and single standard gloves groups (six compared to 76). However, it is unclear how many indicator and standard gloves were included in the study.
Two studies with four study arms reported any perforation to the first inner glove ( Laine ; Laine b DI ). One study with two study arms is included in the meta&#;analysis. The number of perforations to the first inner glove was reduced by 90% when using double indicator gloves compared to standard gloves (RR 0.10, 95% CI 0.02 to 0.45) ( Analysis 7.1 ). The effect was larger when comparing double indicator gloves with the single gloving method (94%) than when comparing with the double standard gloving method (83%).
Turnquest reported the number of blood stains on the skin and could not show a difference in the number of blood stains per gloves used between the two gloving methods (RR 0.98, 95% CI 0.14 to 6.98).
One study ( Sebold ) showed a non&#;significant increase in perforations when using thick gloves instead of wearing one standard glove and one special material glove (RR 15.36, 95% CI 0.88 to 267.57) ( Analysis 6.1 ). Another study ( Turnquest ) reported the outcome per pairs of gloves and did not find a difference in perforations when wearing one layer of thick gloves compared to two layers of standard gloves (RR 0.98, 95% CI 0.44 to 2.19).
Five studies reported the number of perforations to the inner glove ( Chua ; Sebold ) or the number of inner gloves with perforations ( Carter ; Liew Double ; Liew Single ). Study results are inconsistent, with one study favouring thicker gloves, three studies showing non&#;significant results favouring thicker gloves and one study favouring thinner gloves ( Analysis 5.1 ). We did not combine studies in the meta&#;analysis due to high subgroup differences (P value = 0.02; I² = 80.3%).
There was one study that reported the VAS scores for the loss of dexterity for double with fabric glove versus double latex gloves. Participants (n = 18) reported double latex gloves to be less good for tactile sensation, general dexterity, precision with instruments, grip and power, cement handling and comfort compared to double latex gloves ( Analysis 3.2 ).
One study could not be included in the meta&#;analysis. The study reported a 57% reduction per glove pairs used when wearing one standard and one cloth glove compared to two standard gloves ( Tanner , RR 0.43, 95% CI 0.23 to 0.82).
We combined three studies that used fabric gloves and they showed an 87% reduction of inner glove perforations when wearing one fabric and one standard glove (double special) compared to double standard gloves (RR 0.24, 95% CI 0.06 to 0.93). One study showed a non&#;significant reduction of inner glove perforations when using wire weave gloves in double gloving compared to double standard gloves (RR 0.73, 95% CI 0.38 to 1.38) .
We had four studies that compared double special gloves versus normal gloves ( Hester o&#;c ; Louis ; Sanders ; Underwood ) ( Analysis 3.1 ). The difference between subgroups was high (P value = 0.003) and therefore, we did not combine studies using different special material gloves.
We could not include five trials in the meta&#;analysis due to missing data and the results were inconsistent. Four studies reported the number of perforations per glove pairs used. Three studies showed non&#;significant results, with two of them showing an increase and one showing a decrease in outer glove perforations with double gloves ( Doyle , RR 0.75, 95% CI 0.42 to 1.35; Jensen , RR 1.75, 95% CI 0.77 to 1.79; Marín Bertolin , RR 1.20, 95% CI 0.75 to 1.92). One study showed a significant reduction of outer glove perforations with double gloves ( Aarnio , RR 0.26, 95% CI 0.07 to 0.92). The study Berridge did not provide information about the number of gloves used and reported more perforations for double gloves (28 compared to 18).
There were four studies that reported the loss of dexterity for double versus single gloves, measured with a visual analogue scale, but none of these studies reported the data sufficiently to be combined in a meta&#;analysis. All four studies reported less dexterity with the use of double compared to single gloves. Because of the lack of a standardised way of measuring dexterity and the lack of sufficient statistical testing, it is difficult to judge if this decreased dexterity is clinically important or not. We report their published data in Analysis 1.5 .
Three other trials could not be included in the meta&#;analysis. Avery a could not be included because the study did not have any events, either in the double gloving or in the single gloving group. We had to exclude Quebbeman from the analysis because 28% of the participants switched from the intervention to the control group or vice versa. Berridge did not provide information on the number of gloves used but reported that blood contamination to the skin was reduced by half when wearing two pairs of gloves.
One trial did not report sufficient data to be included in the meta&#;analysis and the outcome is calculated per pairs of gloves used. Jensen reported a 80% reduction of perforations using double standard gloves compared to single standard gloves (RR 0.2, 95% CI 0.09 to 0.43).
Six trials did not report sufficient information on the number of persons per operation and could not be included in the meta&#;analysis. All of those trials reported a positive effect of the intervention. Significant results ranged from 96% to 56% fewer perforations in double standard gloves compared to single standard gloves. Four trials reported enough information to show the effect as the number of inner glove perforations per total number of gloves or glove pairs used. The rate ratio in Aarnio was 0.04 (95% CI 0.00 to 0.73), in Doyle 0.15 (95% CI 0.04 to 0.48), in Jensen 0.30 (95% CI 0.16 to 0.57) and in Marín Bertolin 0.44 (95% CI 0.23 to 0.82). Two trials did not provide information on the number of gloves used and only reported the number of perforations ( Berridge ; Laine ). Both studies reported that the number of perforations to the inner glove was reduced with the double gloving method.
We considered the measurement of perforations to be at low risk of bias for studies using both a water leak test and an air inflation test. Only one study used both ( Thomas ). Other studies used either only one of the two or visually inspected the gloves and we therefore judged them to be at high risk of bias.
The measurement of needlestick injuries was a source of bias in all studies that used this outcome ( Doyle ; Marín Bertolin ; Quebbeman ). Needlestick injuries can only be based on self report because there are no other methods of ascertaining that an injury has occurred. Like any occupational injury, the reporting of needlestick injuries increases when workers are more aware of the problem, for example due to an awareness campaign. Any intervention has the same effects as an awareness campaign and is likely to raise the number of reported injuries. This will probably lead to an underestimation of the true intervention effect.
All but one study reported all outcomes that were described in the methods section of the report and we judged the risk of bias as low. Avery b only reported the number of outer glove perforations per type of glove and the number of inner glove perforations was missing, therefore we judged the risk of bias as high.
In 29 studies the risk of bias is unknown because information was lacking as to whether all gloves were reported or it was unknown how many gloves were excluded ( Figure 3 ). Eleven studies reported perforations or incidences for at least 90% of all gloves used during the procedures and cases randomised and we judged the risk of bias as low. One study reported that 17% of the gloves were excluded from the analysis and we judged the risk of bias as high ( Rudiman ).
However, not blinding the outcome assessor is considered a potential risk of bias, when evaluating the effect of the type of glove or gloving. For 27 studies it was unclear if the outcome assessor was blinded and we assessed the risk of bias as unclear ( Figure 3 ). The outcome assessment should be done blind in order to be of low risk of bias and this was reported for three studies only ( Kovavisarach ; Sutton ; Tanner ). In 11 studies, the outcome was assessed by the participants themselves or the gloves were labelled as being used for double gloving and we judged the risk of bias as high.
It is impossible to be blind the glove user to extra or different types of gloves. In spite of this lack of blinding, we assessed the risk of bias as low because it would be difficult for a surgeon to use this knowledge to change the number of needlestick injuries, blood contaminations on the skin or perforations of gloves.
Risk of bias varied considerably over studies ( Figure 2 ). Overall, we considered only one study to have a low risk of bias based on adequate allocation procedures (randomisation and concealment) and blinding of the outcome assessor ( Tanner ). We judged 17 studies to have a high risk of bias, according to their high risk in at least one of these three items ( Figure 3 ). Other studies had both low and unknown risks of bias in these three items (n = 23).
Five studies are not yet included or excluded because the interventions are unclear. All these studies compared different types of single gloves but did not provide information on the characteristics of the gloves used. Four studies refer to the gloves only as A, B, C or D ( Bliss ; Hwang b ; Hwang c ; Hwang d ) and one study reports the name of the gloves used ( Newsom ). We contacted the authors or manufacturer but did not receive an answer. We located one study in the last search update which is still awaiting full&#;text assessment and data extraction ( Guo ).
Based on the full&#;text articles, we mainly excluded studies because they either did not have a primary outcome measure or the methods or comparison were inadequate. For instance, two studies used behavioural changes such as glove use as outcome measure ( Duerink ; Jeffe ) and one study reported alarms by an electronic device meant to detect barrier breakdowns ( Caillot ). In one study the randomisation was unclear and the patients in the intervention and control group were significantly different ( Kelly ). Brunton compared two single, non&#;sterile, powder&#;free gloves and Gaujac compared sterile to non&#;sterile double gloving. Some studies reported results from technical laboratory tests without patients involved. Many studies were of a descriptive nature and as such did not include an intervention.
More than half of the studies were conducted in Europe (19) or the USA (10). Most studies from Europe were conducted in the UK (10). Other European countries were Finland (five), Denmark (two), France (one) and Spain (one). Nine studies were from Asia (Thailand (four), India (one), Indonesia (one) and Oman (three)). Other studies were from Australia (three).
The mean control group rate across nine studies for double standard gloves was 0.515 inner glove perforations per person&#;operation (range 0.011 to 1.067) and 0.210 matched perforations per person&#;operation (range 0.143 to 0.288) across four studies.
A sample of non&#;used gloves was investigated for perforations in several studies as a preliminary control. The number of perforations was always found to be zero or very small. Needlestick injuries or blood contamination incidences were presumed to be zero before the start of the procedure in question.
Glove perforations were detected by filling the gloves with water and observing the jets of water in 36 studies, including one study that added ink to the water. In four studies the gloves were filled with air and then immersed in water, after which the perforations were noted as air bubbles. In one study they were examined visually.
Perforations were recorded with two different measures. Most studies reported any perforation to the innermost glove and some studies reported matched perforations. The first outcome considers every perforation to the innermost glove as a break of the protective barrier and therefore includes all possible exposures. The second outcome, matched perforations, considers perforations as a break in the protective barrier only if the inner glove and the outer glove are perforated in the same area (same spot, finger or side). We reported both outcomes as it is unclear which outcome measurement represents a more valid measure of the risk.
We included two studies with the number of glove pairs used in the meta&#;analysis. The total number of glove pairs was 825, with 343/335 intervention/control pairs in one and 68/79 in the other study.
We included thirty&#;one studies in the meta&#;analysis with an average of 115 person&#;operations in the intervention group (range 15 to 398) and 119 person&#;operations in the control group (range 8 to 443). These studies included person&#;operations in total.
The majority of studies included only surgeons or surgeons and their assistants. Scrub or theatre nurses were included in nine studies. One study also included dental hygienists, one study surgical technicians and three dental studies included surgeons and surgical staff. Twenty&#;six studies included procedures that are related to obstetrics, orthopedics or abdominal surgery. Seven studies did not specify the type of operation but two of these studies stated that the operations lasted longer than one hour. Six studies took place in dentistry workplaces.
All included studies were randomised controlled trials. For every surgical procedure, studies randomised operations, patients, operating teams or individual team members to the type of gloving. In all studies the intervention lasted for the duration of one operation as none of the included studies randomised participants to one type of gloving for the whole duration of the study (e.g. one surgeon has to use double gloves in all procedures during the next four months). Most studies presented the effect per number of gloves used and not per operation per person, which is the unit of randomisation. None of those studies adjusted for the cluster effect. However, we calculated the effect per person&#;operation and included the number of persons and operations as the denominator in the outcome measure. Hence, we included all studies as individual randomised trials.
Six studies compared double indicator gloves to standard gloves (single or double) and only collected the first pair of gloves used during the procedure. Four studies compared double indicator gloves to single standard gloves ( Laine ; Laine a ; Laine b DI ; Naver ). Two studies compared double indicator gloves to double standard gloves ( Laine ; Laine b DI ).
We included two comparisons to standard gloves. The first comparison includes studies that evaluate the theory that the use of indicator gloves reduces the number of perforations in one glove and thus lowers the risk of exposure to bodily fluids (lower number of perforations per glove). The second comparison includes studies that evaluate the theory that the immediate feedback of indicator gloves enables the glove wearer to change their behaviour and protects them from getting additional perforations during the remaining surgical procedure (lower total number of perforations during one procedure).
Indicator gloves are coloured standard gloves and worn under an outer standard glove (double indicator). When an outer glove perforation occurs, moisture from the operating site leaks between both layers and the colour of the inner glove (usually green) becomes highly visible for the glove wearer. The glove wearer can react faster when a perforation occurs and replace the perforated glove with a new glove.
Five studies compared three layers of two normal material and one special material glove (triple special) to two layers of normal material gloves (double normal). Studies used special material gloves between two standard gloves or between one standard and one thicker glove. We included the former as triple special standard and the latter as triple special thicker. Four studies compared triple special standard to double standard gloves ( Pieper l&#;k&#;k ; Pieper l&#;s&#;s ; Sebold ; Sutton ) and one study compared triple special thicker to double thicker (outer standard gloves, inner orthopaedic gloves) ( Hester o&#;c&#;o ).
Two studies evaluated whether thicker gloves are equivalent to glove combinations. The studies compared thicker gloves to two standard gloves and thicker gloves to the combination of standard and special material gloves. Turnquest compared one layer of orthopaedic gloves (thicker than standard gloves) to two layers of standard gloves. Another study compared double thicker (inner standard, outer orthopaedic glove) to triple special gloves (inner standard glove, middle knitted fabric glove, outer standard glove) ( Sebold ).
Five studies compared double gloving with one special material glove and one normal material glove (double special) to double gloving with two normal material gloves (double normal). Four studies used special material gloves made out of knitted fabric (cloth: Sanders ; Tanner ; cotton: Hester o&#;c ; Underwood and one study used wire weave gloves: Louis ). Normal material gloves were standard gloves (standard thickness) in four studies and thicker gloves (orthopaedic gloves) in one study ( Hester o&#;c ).
Studies could be combined into three different comparisons. For the first comparison (special or thicker gloves versus normal gloves) we included studies that evaluated whether special material gloves are better than standard gloves or thicker gloves are better than comparable thinner gloves. Those studies compared single to single, double to double and triple to triple gloves. For the second comparison (special or thicker gloves versus a combination of gloves) we used studies that evaluated whether special material or thicker gloves are equally as effective as two other gloves. Those studies compared single to double and double to triple gloves. For the third comparison (an extra or special glove layer versus no extra layer) we used studies that evaluated whether an extra glove layer of special material or thicker gloves adds additional protection compared to not wearing this extra layer. Those studies compared double to single and triple to double gloves.
Studies used all types of gloves made from special material (e.g. wire or cotton). Studies also evaluated thicker gloves, which are meant to increase protection as a result of thicker glove membranes. Special material gloves are usually permeable to liquids. Unlike thicker gloves that can also be worn as single gloves, in healthcare settings gloves made out of special material are usually worn together with normal material gloves (latex, nitrile rubber or vinyl) in double or triple gloving.
Three studies specified the size of the gloves used. In Wilson a , one half size larger glove was worn over one normal sized glove, Wilson b used the larger glove inside and in Wilson c , two normal sized gloves were used.
Eighteen studies evaluated whether two glove layers offer more protection than one glove layer. Since all studies were carried out among surgeons, the minimum control intervention was at least one pair of standard gloves. There were no studies that compared gloves versus no gloves in healthcare staff other than surgeons. There were no studies that compared three versus one glove layer. One study evaluated whether three glove layers are better than two. We defined wearing one glove layer as single gloving, two layers as double gloving and three layers as triple gloving. An extra layer of gloves could be both standard gloves or indicator gloves. Indicator gloves are coloured gloves, which are usually green and worn as inner gloves under a standard glove. The green colour will show an outer glove perforation when liquid leaks between both layers and the colour of the inner glove becomes highly visible for the glove wearer. Besides the different colour, indicator and standard gloves are similar in thickness and material and the protection with increased glove layers works in the same way. We only included studies using indicator gloves in the comparisons of extra gloves if they had collected all gloves used during one procedure.
With the search strategy described in Appendix 1 and Appendix 2 , after removal of duplicates, we had a total of 11,337 references (11,239 from our search in plus 98 from the search update in ). We selected 336 references for full&#;text reading (322 plus 14 from ). Out of these, we excluded those that did not fulfil our inclusion criteria or that were duplicate publications. In case the article did not provide enough data, we contacted the authors and asked them to send the missing information. If we did not receive sufficient information to judge if the study should be included, we classified the study as awaiting classification. This resulted in 34 articles eligible for inclusion in our review. Five of them had three study arms and two had two study arms. Hence the total number of intervention&#;control comparisons was 46 ( Figure 1 ).
No study compared the effect of gloves versus no intervention in healthcare staff other than surgical staff.
There was moderate&#;quality evidence that double gloving in the form of using two pairs of standard thickness gloves instead of one pair reduced the risk of inner glove perforation for one person for one operation by 71% (rate ratio (RR) 0.29, 95% confidence interval (CI) 0.23 to 0.37). The effect was larger when measuring only matched perforations (89%). The use of two glove layers also reduced the risk of blood contamination by 65% (RR 0.35, 95% CI 0.17 to 0.70) compared to one glove layer. Double gloves reduced the number of reported needlestick injuries by 42% in two studies, but the result was not statistically significant (RR 0.58, 95% CI 0.21, 1.62) because this was based on 16 events only. The effect of double gloves compared to single gloves was similar when restricted to studies from low&#;income countries, to studies from countries with a high prevalence of HIV or hepatitis C and to studies with high exposure rates.
Three layers of standard gloves or gloves made out of special material in combination with standard gloves can provide additional protection. There was low&#;quality evidence for a 97% reduction in the number of perforations with three layers of standard gloves compared to two layers but this is based on one small study only.
The use of double fabric gloves (one fabric and one standard material glove) compared to two standard material gloves reduced the risk of inner glove perforations by 76% (95% CI 6% to 94%) and is based on low&#;quality evidence from three studies only. Our sensitivity analysis (excluding one study at high risk of bias) increased the effect of double fabric gloves compared to double normal gloves from 76% to 87% (RR 0.13 95% CI 0.06 to 0.29) and the I² statistic for heterogeneity dropped from 78% to 0%.
The effect of double fabric gloves compared to double normal gloves is similar to the effect of triple special gloves (two standard and one special material glove). There was moderate&#;quality evidence that triple special gloves compared to double normal gloves reduced the risk of perforations by 76% (RR 0.24, 95% CI 0.13 to 0.45). This was shown for fabric, Kevlar, steel and spectra polyethylene fibre gloves.
There was moderate&#;quality evidence that double indicator gloves compared to standard gloves (single and double gloves) reduced the number of perforations in one glove on average by 90% (RR 0.10, 95% CI 0.02 to 0.45). When perforations occur, the glove is replaced faster with an intact glove layer. However, the use of indicator gloves did not significantly reduce the total number of inner glove perforations for one person during one operation compared to double gloves without the indicator system (RR 0.72, 95% CI 0.36 to 1.42).
In five low&#;quality studies, thicker gloves had a similar risk of inner glove perforations compared to thinner gloves (RR 0.63, 95% CI 0.37 to 1.08).
As a proxy measure of loss of dexterity due to double gloving, eight studies compared the number of perforations in the outer glove of the double gloves to the number of perforations in single gloves and found this to be similar (RR 1.10, 95% CI 0.93 to 1.31).
Perforations are a proxy measure for actual needlestick injuries. We assume that needlestick injuries are proportional to the number of perforations even though we do not have good evidence to underpin this assumption. There were two studies that measured both perforations and needlestick injuries in this review. The rate ratio for these two outcomes differed substantially (RR 0.32 and RR 0.57, respectively). In the review by Parantainen there were four studies that measured both these outcomes and there was no difference between the RRs, but this could also be due to the use of blunt needles as the intervention. However, laboratory studies (Edlich ) showed that the penetration through two glove layers requires considerably more force than the penetration of one layer only and, thus, supports the idea that extra glove layers mechanically prevent needlestick injuries.
The measurement of needlestick injuries is notoriously difficult because it relies on self report, which is easily biased by awareness of the problem (Boal ). Thus it could be that reporting is more frequent with double gloving because this would draw more attention to the problem of needlestick injuries. It could also be that some needlestick injuries with single gloves do go unnoticed because less force is needed to perforate the glove barrier. Given these measurement problems it is not likely that the effect on needlestick injuries can be assessed with more certainty.
The effect of double gloving on dexterity was not fully clear in this review because only three studies measured and reported this adverse effect, with two studies showing a slight decrease in dexterity, but one study rating dexterity for double gloves as poor. As a proxy but objective measure for loss of dexterity, we assumed that needlestick injuries would be more frequent in the outer glove of double gloves than in single gloves. However, this was not the case. Additionally, we found one study that evaluated dexterity in the laboratory under standard conditions and found that double gloves did not influence dexterity (Fry ). We believe, therefore, that there is no serious impairment of dexterity from double gloving.
Studies included in this review covered a time period from to and apparently were initiated by the HIV epidemic and the risk of contamination for surgical staff. The number of glove studies reached a peak in the s and then decreased again. We found nine studies from low and middle&#;income countries (at the time of the study) (World Bank ). Four studies were from Thailand (, , , ), one from Indonesia (), one from India () and three from Oman (). Only three studies were from an area with more than 1% prevalence of HIV (Thailand) and 12 studies were from an area with more than 2% prevalence of hepatitis C among the adult population (Indonesia, Australia, Thailand, Oman) (Centers for Disease Control ).
Most studies could be described as pragmatic trials because they were carried out by the healthcare staff who were themselves at risk. This increases the applicability of the evidence but at the same time has probably decreased the quality of studies. This has also led to a lack of trials with nurses as study participants. Studies included only operations or dental procedures, excluding other healthcare procedures with exposure risks, such as blood sampling by phlebotomists. Some authors have argued that double gloves protect against sharps injuries with surgery needles but protect much less against injuries with hollow&#;bore needles (Bouvet ). It could therefore be that the effects are less in other participants with tasks different from surgery. Although one study with nurses as study participants is awaiting classification, all participants were part of the operating staff and were thus not very different from the participants of the studies included in this review.
We included only randomised controlled trials, even though there were also many non&#;randomised studies available. Therefore, the studies included are the better&#;quality studies. Nevertheless, we rated the quality of the included studies as at best moderate. This could have resulted from most studies being performed by surgeons themselves and not being set up by a research institute. The reporting of randomisation methods and allocation concealment was especially unclear and because many studies were over 20 years old, it was impossible to get clarification from the authors.
Even though glove perforations form a fairly objective method of assessing potential exposure to blood, the differences in reporting this outcome decreased its validity. It is unclear in which direction this bias would go. Ideally one would like to know the number of perforations per physician/nurse per unit of exposure time, for example the number of perforations per 100 physician/nurse hours at risk. For operations, this would not be very difficult to calculate as was shown by Meyers . Consensus on this measure is needed. We also rated the risk of bias from outcome assessment as high when the authors had not used a combined water and air test to assess perforations. Current European standards also specify that, to test gloves for perforations, both a specific water test and air test should be used to assess whether a glove achieves the acceptance quality level (level 2 for surgical gloves which means that perforations are allowed in 1.5% of new gloves) (CEN ). However, we believe that this bias has not influenced the results of the review to a great extent because the same measurement error would apply to both the intervention and the control group.
In spite of these limitations, and given the relatively large effect size and the consistency of the evidence, we believe there is no need for more and better studies on double gloving.
For triple gloving, special material gloves and thicker gloves, the evidence was less clear and we do see a need for more and better&#;quality studies.
We did not exclude articles in languages other than English. Therefore, even though few were found, we are confident that there is no language bias in our review. We carried out all selection and data extraction processes in duplicate and involved a third assessor if we could not easily reach consensus.
We did not see publication bias in the funnel plot of the double gloving studies and also the Egger's test was non&#;significant. Even though glove manufacturers must have a financial interest in the results of double gloving studies, because double gloving will increase the amount of gloves sold, we did not see involvement of the manufacturers in the included studies.
Several reviews have been published on the prevention of percutaneous exposure incidents in the past but only two included gloves as the intervention. Compared to the earlier review of Rogers , the number of included studies increased enormously. Probably due to an non&#;comprehensive search strategy the authors found only four studies, whereas we located 45. Tanner is a Cochrane Review on the prevention of surgical cross&#;infection and glove perforations are only included as a secondary outcome. The review limited the inclusion of studies to surgical team members and included 31 randomised controlled trials. We included three more studies but did not find studies outside surgery. Two trials included in the review by Tanner assessed infections but did not find any. Based on the same studies as were included in this review, the authors concluded that double gloving protects against glove perforations even though they calculated odds ratios to assess the treatment effect. Given the high incidence of perforations odds ratios will provide an overestimate of the effect. Therefore, we believe that the rate ratios that we calculated for this review are a more appropriate estimate of the treatment effect. A more recent review by Yang identified only 10 studies, eight RCTs and two cohort studies that evaluated double gloving (Yang ). The authors did not perform a meta&#;analysis but still concluded that double gloving was effective.
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