Despite the perception that operating rooms (ORs) are sterile environments, this is clearly not the case. Anesthesiologists have occasionally raised concerns about infection spread and cross-contamination in the OR for >2 decades.1 The inanimate hospital environment is a reservoir for resistant organisms,2 and frequent contact with upper airway secretions and small volumes of blood3 lead to potential contamination of anesthesia providers and their surroundings (including laryngoscope,4–9 anesthesia machine,3,10 computer keyboard,11 stopcock,12 and IV tubing).13 A few simple solutions have been proposed to limit potential transfer of oral flora, blood-borne pathogens, and bacterial contamination to the patient and anesthesia workspace,9,10,14,15 but there is little evidence that these solutions are being embraced or considered as the standard of care.16 The practice of hand hygiene, despite the American Society of Anesthesiologists’ recommendations,17 is not practiced regularly. Therefore, the introduction of an intervention that may minimize contamination after endotracheal intubation is a viable option for potentially reducing infection risk. Anesthesiologists are leaders in evidence-based practice, and our goal was to design a study that could provide data to inform current infection-prevention practices. It has been suggested that the use of 2 sets of gloves for intubation may prevent the contamination of clean syringes, tubes, airways, and other equipment on the anesthesia table,1,18 but this has not been tested adequately. Using technology that was previously reported to identify where oral pathogens are spread during routine intubation,19 we sought to determine whether wearing 2 sets of gloves would limit contamination in the OR as compared with standard (single-gloved hands) practice. Our first study conducted in a simulated OR demonstrated that anesthesiologists are indeed a vector for pathogen spread,19 which occurs in various OR locations that may not be cleaned routinely between cases.2 Based on those findings, we hypothesized that wearing double gloves would decrease contamination of various locations in the OR. The aim of the current study was to compare the pathogen spread and number of contaminated sites when anesthesia providers wore a single set of gloves versus a double set of gloves with the outer set removed immediately after tracheal intubation.
This study was exempted by the University of Miami Miller School of Medicine IRB. Forty-one anesthesiology residents (PGY2-4) were enrolled in a study either as individuals or groups with a total of 22 simulation sessions recorded as a convenience sample. The study was conducted at the University of Miami-Jackson Memorial Hospital Center for Patient Safety, a state-of-the-art simulation center. Residents were assessed either as individuals (10) or as members of teams (12) to mimic realistic scenarios where >1 anesthesia provider may be present in the OR. The study was designed as a double-blinded, controlled, randomized trial.
As part of an educational program conducted for 44 weeks (approximately every other week), anesthesiology residents participated in a simulation-based educational program. Individuals were being trained for knowledge and technical skills, whereas groups were being primarily trained to function better as teams. Unbeknownst to the residents, we evaluated the spread of a surrogate marker for oral pathogens. Sessions were randomized as to single or double gloves on a 1-to-1 ratio. All residents who participated were eligible.
All participants wore gloves at the start of the scenario. Of the 22 simulation sessions, 11 were conducted with the intubating resident wearing single gloves, and 11 with the intubating resident wearing double gloves with the outer pair removed immediately after the placement of the endotracheal tube. The study was randomized by random number generation as to who wore single or double gloves. The primary outcome was the number of contaminated sites at the end of the simulation. A second outcome was to determine whether other clean anesthesia-related materials, including unused syringes, were contaminated if the laryngoscope was placed on the anesthesia machine surface after use.
Residents were asked to perform an anesthetic induction and intubation in an OR scenario that was timed to approximately 6 minutes, but they were unaware of the study design. As previously reported,19 before the start of the scenario, the lips and inside of the mouth of the mannequin (CAE, Quebec, Canada) were coated with 0.5 mL DAZO fluorescent marking gel (Ecolab, St. Paul, MN) as a surrogate for oral cavity pathogens or blood. Residents who wore single gloves were instructed to remove their gloves at the completion of the scenario if they had not done so on their own. Residents who wore double gloves were instructed by a nurse who was present in the OR (confederate nurse) to remove the outer set immediately after completion of the tracheal intubation, before contact with their surroundings. Forty sites of potential intraoperative pathogen spread were identified a priori and assigned a score of zero (no fluorescence) or 1 point (positive fluorescence; range 0–40). These 40 sites were previously reported in a validation study.19 After the simulation was terminated, an observer blinded to whether the residents wore single or double gloves examined all identified sites using a handheld ultraviolet light in the OR to determine the transfer of fluorescence to the patient and the surrounding environment. The observer was different from the investigator who created the random allocated sequence and enrolled participants.
As previously described,19,20 the OR was cleaned between cases with both alcohol-based hand rub as well as soap and water to remove all previously placed fluorescent marker. To verify that the OR was adequately cleaned before each simulation, an observer examined the OR using a handheld ultraviolet lamp to determine the presence of any residue of fluorescent marker. If residual marker was found, it was removed before initiation of the next simulation. Disposable materials that could not be easily cleaned (reservoir bag, IV tubing, and syringes) were replaced between simulations. The residents did not know that DAZO had been applied to the mannequin and did not alter standard practice and thus were blinded to the intervention.
The proportion of objects positive for fluorescent markers based on single versus double-glove usage was analyzed using χ2 or Fisher exact test as appropriate. Poisson regression was used to analyze the total number of contaminated sites. The regression model included the intervention group (single versus double gloves), the number of team members (1, 2, or 3), and the interaction of group and number of team members. Results are reported as mean and standard error (SE). SAS 9.3 (SAS Institute Inc., Cary, NC) was used for all analyses. Since this was an exploratory study, no power analysis was performed. Sample size was limited by the number of participants in the course. The 0.01 significance level was used to determine statistical significance because there was no previous power analysis.
All participants completed the study and remained in the group to which they were assigned. Three participants (all in the single-glove group) removed their gloves after intubation, the remainder continued to wear gloves until termination of the scenario. Team sizes were nearly evenly distributed between the single and double-glove groups. The difference in the rate of contamination between anesthesiology residents who wore single gloves versus those with double gloves was clinically and statistically significant. The number of sites that were contaminated in the OR when the intubating anesthesiologist wore single gloves was 20.3 ± 1.4, while the number of contaminated sites by residents wearing double gloves was 5.0 ± 0.7 (P < 0.001). The average number of contaminated sites in the single-glove group was 4.1 times higher than the average in the double-glove group (99% confidence interval, 2.6–6.5). The number of participants on the anesthesia team did not have a significant effect on the outcome (P = 0.557); furthermore, the effect of the number of participants was consistently non-significant within the groups (P = 0.395).
Of note, the areas that were more frequently contaminated when residents wore single gloves versus double gloves included the anesthesia machine surface towel (100% vs 18.2%; P < 0.001), reservoir bag (81.8% vs 9.1%; P = 0.002), and suction tubing (72.7% vs 0.0%; P = 0.001). Rates of contamination of commonly affected sites, with the intubating resident wearing either single or double gloves are illustrated in Table 1. Figure 1 illustrates the sites where fluorescence was observed in the simulated OR (asterisk = site of fluorescence). Four contaminated sites (door handle, door, OR light control, and overhead light switch) are not observable in this figure.
Placing the contaminated laryngoscope on the clean anesthesia machine surface resulted in workspace contamination regardless of single or double-glove use. Figure 2 displays the fluorescence on the laryngoscope handle as well as the surrounding surface when the laryngoscope was placed on the clean tabletop towel after use. Figure 3 displays fluorescence seen on the oxygen flow control knob, showing a partial fingerprint. Every surface (n = 40) we examined in our study during single gloving was contaminated in at least one of the simulation sessions, even equipment not used (such as the extra laryngoscope handle [91%] and blade [82%] and computer keyboard [36.4%]).
The results of this study suggest that when an anesthesiologist wears 2 sets of gloves during laryngoscopy and endotracheal intubation and then removes the outer set immediately after intubation, the contamination of the intraoperative environment is reduced as compared with that of standard practice (which may not include adherence to the American Society of Anesthesiologists’ recommendations). In addition, where the laryngoscope handle and blade should be placed after intubation is consequential and demands further study. The contamination of the OR door handle occasionally seen in this study affects all personnel; not only the anesthesia providers but also may impact contamination of other ORs and hospital locations. We believe that these findings indicate that the use of double gloves for intubation with the removal of the outer pair after completion of the procedure should be considered for adoption as a standard practice. It is not uncommon for an anesthesia provider to prepare syringes and other equipment for the next case, while still in the OR completing the current case. Our data suggest that this practice is at odds with appropriate infection control procedures, because the material prepared for a different case would be at great risk of contamination from the current patient.
Without previous instruction, 2 residents in the double-glove group placed the contaminated laryngoscope blade in the outer glove when it was removed so that the blade was contained in a sheath formed by the outer glove. The containment of the blade was neither an aim of this study nor was this study powered to evaluate this practice. But it is interesting that in neither of these cases was the anesthesia machine surface nor unused syringes contaminated. Of interest, not a single resident in the single-glove group performed hand hygiene after placement of the endotracheal tube. This is not surprising based on previously published observations.16
This study has several limitations. First, it was conducted in a simulated OR using a surrogate marker for oral pathogens and was performed only among anesthesiology residents. Behaviors in an actual OR, or among attending anesthesiologists, might be different. Second, residents were limited to approximately 6 minutes for performance of the scenario. An actual case typically takes much longer and may potentially lead to additional contaminated sites. Further, we selected 40 potential sites for contamination; in an actual OR, there may be numerous additional contaminated sites. Moreover, the presence of fluorescent markers on surfaces reflects transfer of fluorescent marker from the mouth to the surfaces, but we cannot prove that this would imply either bacterial contamination or future patient infections. However, we believe that the reduction of the spread of secretions from the patient’s mouth to the OR environment is in everyone’s best interest. Although conducted in a simulated setting, previous studies suggest that these results are generalizable in our OR and to ORs in other hospitals.16,19 Future studies are needed to establish the containment of oral cavity pathogens using double gloves and particularly the impact of using the outer glove as a sheath for the used laryngoscope blade.
Name: David J. Birnbach, MD, MPH.
Contribution: This author helped design and conduct the study, analyze the data, and write the manuscript.
Attestation: David J. Birnbach has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.
Name: Lisa F. Rosen, MA.
Contribution: This author helped design the study, analyze the data, and write the manuscript.
Attestation: Lisa F. Rosen has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Maureen Fitzpatrick, MSN, ARNP-BC.
Contribution: This author helped design and conduct the study and write the manuscript.
Attestation: Maureen Fitzpatrick has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Philip Carling, MD, MPH.
Contribution: This author helped design the study and write the manuscript.
Attestation: Philip Carling has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Kristopher L. Arheart, EdD.
Contribution: This author helped design the study and analyze the data.
Attestation: Kristopher L. Arheart has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: L. Silvia Munoz-Price, MD, PhD.
Contribution: This author helped design the study, analyze the data, and write the manuscript.
Attestation: L. Silvia Munoz-Price has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).
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© 2015 International Anesthesia Research Society
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