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Patient Safety: Brief Report

The Use of a Novel Technology to Study Dynamics of Pathogen Transmission in the Operating Room

Birnbach, David J. MD, MPH*∥; Rosen, Lisa F. MA; Fitzpatrick, Maureen MSN, ARNP-BC; Carling, Philip MD, MPH; Munoz-Price, L. Silvia MD, PhD§∥¶

Author Information
doi: 10.1213/ANE.0000000000000226
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The operating room (OR), while considered to be the hallmark of cleanliness, is not a sterile environment.1,2 Studies have shown that ORs are adequately cleaned during a 24-hour period in <50% of instances.2 Known pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Clostridium difficile, and multidrug-resistant Gram-negative bacilli have been found on many OR surfaces.2–4 Models of bacterial transmission in the OR have definitively shown that anesthesia providers play an important role,5 and it has been suggested that anesthesiologists may be a key vector for the spread of bacteria through their contaminated hands or gloves.6,7 This occurs by transferring organisms from the patient to the immediate environment (including the anesthesia machine) and then from the contaminated environment back to the patient. Therefore, a better understanding of how organisms are spread in ORs may help to provide the basis for developing evidence-based preventive measures in the future.1,8,9 We used an experimental technology in a simulated environment to show patterns of transmission and evaluated the efficacy of this technology for studying dynamics of pathogenic contamination in an OR.

Using a previously validated experimental technology2 in a simulated OR with anesthesia residents providing the anesthetic, we aimed to: (1) evaluate the use of a new technology to study the transmission of bacteria and blood in an OR; (2) show how a contaminated patient (mannequin) can lead to pathogen spread in the OR environment with the anesthesia provider acting as a vector; and (3) characterize and quantify the number of objects contaminated by the anesthesia provider after the intubation.


IRB exemption for this study was obtained. Ten anesthesiology residents (PGY 2–3) were enrolled in individual training sessions conducted in a simulated OR. On entry to the simulation session, each resident was asked to perform an anesthetic induction and intubation on a human patient simulator. These exercises were realistic; however, the residents were told that they did not need to record the anesthetic or use the computer keyboard. These simulations were designed to last 6 minutes and were part of an educational program that did not relate to glove use. Before the start of the scenario, the lips and inside of the mouth of the human patient simulator (CAE, Quebec, Canada) were coated with 0.5 mL fluorescent marker (DAZO, Ecolab, St. Paul, MN).2 As part of the orientation, all residents were instructed to don gloves before the start of the scenario, but no further instructions regarding glove use were provided. If gloves were not removed when the simulation was terminated, the resident was asked by the nurse who was present during the scenario to remove them before leaving the OR.

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 entire OR using a handheld ultraviolet light to determine the presence of any residue of fluorescent marker. If residual marker was found, it was removed. Disposable materials that could not be easily cleaned were replaced (reservoir bag, IV tubing, and syringes). After the resident had left the OR, an observer used an ultraviolet marker to determine the objects positive for fluorescence. The residents did not know that DAZO had been applied and did not alter standard practice.

The proportion of objects with fluorescent markers after the encounters was analyzed based on the resident’s level of training using χ2 or Fisher exact tests as needed. P < 0.05 was considered statistically significant. SAS 9.2 (SAS Institute, Inc., Cary, NC) was used for all analyses.


Forty potential sites within the resident’s working environment were examined for the presence of fluorescent markers (Table 1). The mean number of objects stained with fluorescent marker per session was 31 (range 27–35). Thirteen sites, including the IV hub, were contaminated in 100% of the sessions (Table 2). Fluorescence demonstrating contamination of IV hub is illustrated in Figure 1. Numerous areas of the mannequin’s face (nose, eyes, and forehead) were found to be contaminated, as shown in Figure 2. Table 3 identifies those areas that were contaminated only occasionally. Of note, the OR door handle was contaminated in 60% of cases despite the fact that no one left the OR with gloves on, suggesting that residents were contaminating their hands at some point before contact with the door handle. In 100% of the cases, when the laryngoscope was placed on the anesthesia machine surface immediately after use, the adjacent surface and syringes were contaminated. Of interest, even unused equipment (including the computer keyboard) was contaminated in most cases. Contamination of the keyboard is shown in Figure 3. There was no difference between levels of years of residency training in number of areas contaminated (PGY 2 = 31.2, PGY 3 = 31.4, P = 0.12).

Table 1
Table 1:
Operating Room Areas Observed for Presence or Absence of Fluorescence After Each Simulation
Table 2
Table 2:
Locations Which Were Contaminated in 100% of Scenarios
Table 3
Table 3:
Other Contaminated Areas and Percentages
Figure 1
Figure 1:
Contamination of IV hub.
Figure 2
Figure 2:
Fluorescence on mannequin’s face after scenario.
Figure 3
Figure 3:
Computer keyboard.


This study demonstrates the use of a novel technology for studying the spread of pathogenic material (e.g., blood or bacteria) in a simulated OR. We found a high degree of spread of fluorescent marker placed at the mannequin’s mouth to the OR environment. These data suggest that this technology will be useful as a tool to evaluate methods to decrease OR contamination. In addition, the findings support previous reports that anesthesiologists may be a vector for spread of pathogens from the patient to the intraoperative environment.5 In addition to providers’ hands, the IV hubs, laryngoscopes, and OR door handles appear to be surfaces that might increase the possibility for horizontal transmission of organisms among patients sharing the OR throughout the day. Moreover, the placement of a laryngoscope immediately after use on the surface of the anesthesia machine adjacent to clean syringes may create unnecessary risk of contamination of other objects with bodily fluids. Some of the areas stained by fluorescent markers in this study (including the box of nonsterile gloves) are not routinely cleaned between cases, if at all. Even if the anesthesiologist were to continually perform hand hygiene during surgery, if initial contamination from the patient to the environment occurs, there is a large risk of recontamination during the recurrent handling of the head of bed, anesthesia machine, syringes, or stethoscope.

This study has several limitations. First, it was conducted in a simulated OR using a surrogate marker for blood and oral pathogens. Behaviors in an actual OR might be different. Second, the scenario was limited to 6 minutes for performance of the induction and intubation. An actual case takes longer and may potentially lead to additional contaminated sites. Third, the examination of all mechanisms of transmission was beyond the scope of the study because it involved a small cohort of residents. Last, possible contamination was limited by the study design because other areas in the OR and areas outside the OR were not investigated for spread of fluorescence. In addition, this study was not randomized to evaluate the differences between those who removed their gloves immediately after intubation and those who did not. Although the American Society of Anesthesiologists recommendations state that gloves should be removed before touching equipment,9 this is not routinely done.10 This lack of compliance was evident in this study, where none of the residents removed their gloves before contaminating the OR environment.

Despite these limitations, our findings strongly suggest that anesthesiologists need to be conscious of the role they may play in pathogen transmission in the OR. Future studies with more robust approaches should compare the spread of fluorescent marking gel when gloves are removed immediately after intubation versus leaving them on for a sustained period as well as the potential benefit of wearing 2 sets of gloves. The use of this technology can also be used to evaluate strategies to decrease potential spread of oral pathogens in a real OR environment, as well as in other areas where anesthesiologists work such as postanesthesia care units, intensive care units, and pain clinics.


Name: David J. Birnbach, MD, MPH.

Contribution: This author helped in design and conduction of study, data collection, data analysis, and manuscript preparation.

Attestation: David J. Birnbach reviewed the original study data and data analysis, attests to the integrity of the original data and analysis, approved the final manuscript, and is the archival author.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Lisa F. Rosen, MA.

Contribution: This author helped in study design, data analysis, and manuscript preparation.

Attestation: Lisa F. Rosen approved final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Maureen Fitzpatrick, MSN, ARNP-BC.

Contribution: This author helped in design and conduction of study, data collection, and manuscript preparation.

Attestation: Maureen Fitzpatrick approved final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Philip Carling, MD, MPH.

Contribution: This author helped in design and manuscript preparation.

Attestation: Philip Carling approved final manuscript.

Conflicts of Interest: Consulting fee and patent license with Ecolab, Inc.

Name: L. Silvia Munoz-Price, MD, PhD.

Contribution: This author helped in design and conduction of study, data collection, data analysis, and manuscript preparation.

Attestation: L. Silvia Munoz-Price approved final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).


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© 2015 International Anesthesia Research Society