infection control & hospital epidemiology july 2017, vol. 38, no. 7 letters to the editor


Priority of Patient Safety Associated With Robotic Surgical Instruments—Response to Landenberg et al


To the Editor—We read with interest the letter by Landenberg et al.1 We would like to respond to the questions raised by the authors regarding our article.2 The authors expressed concerns about the size or surface area of the instruments.1 They claimed that the assessment should have been confined to the area in direct contact with patients. This critique would be reasonable only if there were no transfer of contamination from the distal part to the proximal part. However, in terms of robotic instruments, it has been reported that surgical soil can travel up the shaft by gravity because the shaft is quite open.3 We believe that the inside surface of the shaft should also be included in the measurement; therefore, we assessed the total amount of contamination of whole instruments. The possibility of a false-positive effect was raised by the


authors. They expressed concerns that higher protein values might be obtained due to substances from the distal working part and shaft, even after cleaning the instruments.1 This effect is thought to be caused by soil that originates from the manufacturing process.3–5 The effect can be minimized by reprocessing 3 times.3–5 In our study, however, the instru- ments had already been cleaned 10 times following the manufacturer’s instructions, which exceeded the cleaning process in previous studies.2 Thus, it is not likely that our results were influenced by false-positive effects. The authors claimed that the total protein from all the


instruments used in a single operation should be compared rather than per-instrument protein.1 However, methods based on per-instrument measurement have been established to evaluate the cleanliness or cleaning efficacy of surgical instru- ments.3–6 The authors did not cite any relevant articles justi- fying their proposal; there is no basis for their claim. We agree with the authors that protein itself does not have


the ability to cause wound infections.1 Risk of infection asso- ciated with surgical instruments should be linked to the bac- terial number and strain at the point of use. However, these do not necessarily persist for a long time, and they fluctuate over time. We believe that the results of the protein assay represent the maximum potential for infection. Many studies and guidelines adopt protein assay to assess contamination of surgical instruments.3–6 The authors’ comments appear to be broad. Again, they ignore the established approach to assessing contamination. Decreased incidence of surgical site infection by robotic


surgery has been reported, as stated in the articles cited by the authors of the letter.1,7 However, the incidence of infection could


be affected by publication bias.8 It is not possible to determine the actual incidence of infection related to accidental events because they tend not to be reported. Also, cases would not be identified when symptoms are not recognized as being associated with infection.8 In fact, there are reports of serious postoperative infections after 3 separate robotic surgical procedures, although thecauses wereunknown.9 Similar cases may have occurred in other patients who had a longer hospital stays without infection being diagnosed. Presently, we do not have an appropriate modality to determine the actual incidence of occult infection. We do not agree with the authors’ claim based only on the reported incidence of infection.7 The aim of our article was to provide accurate information


to avoid pitfalls such as cleaning failure. We are simply con- cerned that cases such as those mentioned above might occur sporadically, like outbreaks associated with endoscopic retro- grade cholangiopancreatography procedures.10 Technology should not be developed ignoring safety. We believe that true innovations bring novel technology by applying principles of patient safety.


acknowledgments


Financial support. This studywas supported by a Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (grant no. JP 15K19259). Potential conflicts of interest. All authors report no conflict of interest related


to this article. Yuhei Saito, MS;


Hiroshi Yasuhara, MD, PhD; Satoshi Murakoshi, MD, PhD; Takami Komatsu, MD, PhD; Kazuhiko Fukatsu, MD, PhD; Yushi Uetera, MD, PhD;


Affiliation: Surgical Center, The University of Tokyo Hospital, Tokyo, Japan. Address correspondence to Yuhei Saito, MS, Surgical Center, The University


of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 113-8655 (saitoyu- ope@h.u-tokyo.ac.jp). Infect Control Hosp Epidemiol 2017;38:879–880 © 2017 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2017/3807-0020. DOI: 10.1017/ice.2017.95


references


1. Landenberg N, Cole AP, Gild P, Trinh QD. Challenging residual contamination of instruments for robotic surgery in Japan. Infect Control Hosp Epidemiol 2017;38:501–502.


2. Saito Y, Yasuhara H, Murakoshi S, KomatsuT, Fukatsu K, Uetera Y. Challenging residual contamination of instruments for robotic surgery in Japan. Infect Control Hosp Epidemiol 2017;38:143–146.


3. Wallace BH, Wille F, Roth K, Hubert H. Results of performance qualification testing on clinically-used da Vinci Endowrist instru- ments at hospitals in Germany. Central Service 2015;3:182–187.


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