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Randomized Controlled Trial
. 2025 May 1;120(5):1027-1035.
doi: 10.14309/ajg.0000000000003093. Epub 2024 Sep 23.

A New Drying Method of Thermolabile Flexible Endoscope Channels by Laminar and Turbulent Airflow: A Prospective, Randomized-Controlled, Single-Center, Proof-of-Concept Trial

Florian A Michael  1 , Michael Jung  1 , Mike Reimers  1 , Clara Oschwald  1 , Ulrike Mihm  1 , Christoph Welsch  1 , Dirk Walter  1 , Fabian Finkelmeier  1 , Johannes Masseli  1 , Anita Pathil  1 , Georg Dultz  1 , Danuta Puhlmann  2 , Laura Diaz-Martinez  2 , Daniel Hack  2 , Neelam Lingwal  3 , Jörg Bojunga  1 , Volkhard A J Kempf  2 , Stefan Zeuzem  1 , Mireen Friedrich-Rust  1
Affiliations
Randomized Controlled Trial

A New Drying Method of Thermolabile Flexible Endoscope Channels by Laminar and Turbulent Airflow: A Prospective, Randomized-Controlled, Single-Center, Proof-of-Concept Trial

Florian A Michael et al. Am J Gastroenterol. .

Abstract

Introduction: International guidelines suggest different possibilities for drying of endoscopes during reprocessing. Clinical results of these available drying methods are not satisfactory. The aim of this study was to compare the drying cycle of a standard endoscope washer-disinfector (EWD) (standard drying method [SD]) with a shortened mandatory drying by the EWD followed by a special drying device using laminar and turbulent air flow (novel drying method [ND]).

Methods: Sixty endoscopes (duodenoscopes, colonoscocopes, and gastroscopes) from 3 different manufacturers underwent high-level disinfection and drying depending on the randomization group. Operational time of drying was measured for both groups. Residual fluid in the channels was measured using a laboratory scale. After a 14-day storage period, a sample of the endoscope channels was obtained to determine bacterial contamination.

Results: ND had significantly fewer residual water in endoscope channels (SD: 90% vs ND: 0%; P < 0.001) after high-level disinfection and drying and less bacterial contamination after storage for 14 days (SD: 47% vs ND: 20%; P = 0.028). Time consumed for drying in ND was also significantly shorter (SD: 16 minutes 4 seconds vs ND: 5 minutes 59 seconds; P < 0.001).

Discussion: Drying with a special automatic drying device was superior compared with an EWD's drying program as evidenced by no measurable residual water, reduced microbiological contamination, and a more than 2-fold decrease in operational time. Thus, drying by laminar and turbulent airflow may represent an attractive alternative to the currently used standard approach in the reprocessing process of flexible endoscopes.

Keywords: disinfection; drying; endoscopes; equipment contamination*; gastrointestinal/microbiology*.

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Conflict of interest statement

Guarantor of the article: Florian A. Michael, MD.

Specific author contributions: F.A.M., M.F.-R., and M.J.: developed the study conception and design. Material preparation was performed by F.A.M., M.F.-R., M.J., and N.L. Data collection was performed by all authors except for N.L. Analysis was performed by F.A.M. and N.L. The first draft of the manuscript was written by F.A.M. and by M.J. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Financial support: The trial was supported by Pentax Medical. One PlasmaTyphoon+, 2 gastroscopes, 2 colonoscopes, 2 duodenoscopes, a fully equipped endoscopic tower including a processor and additional single-use consumables to support the products were provided for the duration of the trial (12, 2021–12, 2023). Beyond, Pentax Medical financed the analysis of the 60 samples with 3.048,60 euros. However, the study was entirely investigator initiated with study design, data collection, analysis and interpretation performed independently by investigators. The study presented manuscript was not influenced by the company.

Potential competing interests: F.A.M. has received lecture fees from Pentax Medical and Chemische Fabrik Dr. Weigert GmbH & Co. KG. M.R. has received lecture fees from Pentax Medical. All other authors do not have any competing interests.

The trial was approved by the local ethics committee (2021-190) and was registered at the German Clinical Trials Register (DRKS00025582) before enrollment started.

Figures

None
Graphical abstract
Figure 1.
Figure 1.
Graphical visualization of randomization process. After performing all manual and automated washing and disinfection steps, every endoscope underwent their predefined drying program according to randomization in either SD or ND. SD: The endoscope channels were dried for approximately 15 minutes by constant laminar air flow by the drying program of the EWD. ND: In the first step, the endoscope channels were also dried with laminar air flow by a shortened drying program for approximately 2.5 minutes in the EWD. In the second step, the endoscopes were then connected to a special automated drying device (PlasmaTyphoon+) and all channels were dried for another 2.5 minutes. Compared with drying in the EWD, which applies constant compressed air to the endoscope channels over the entire drying period, the novel drying device uses a sophisticated drying process. First, fluid in all endoscope channels was removed using a forceful laminar air flow. Then, remaining fluid was removed by a turbulent airflow. Thereby, adherent droplets are dissolved and removed, resulting in completely dry endoscope channels according to the manufacturer. EWD, endoscope washer-disinfector; ND, novel drying method; SD, standard drying method.
Figure 2.
Figure 2.
Study flow chart. SD: drying by EWD for approximately 15 minutes by constant laminar air flow. ND: drying by shortened drying program for approximately 2.5 minutes in the EWD and then for another 2.5 minutes by an automated drying device using laminar and turbulent airflow (PlasmaTyphoon+). F, Fujifilm; O, Olympus; P, Pentax Medical; EWD, endoscope washer-disinfector; ND, novel drying method; SD, standard drying method.
Figure 3.
Figure 3.
Overview of microbiological contamination of endoscope channels depending on the study group. Standard drying method (SD): drying by endoscope washer-disinfector (EWD) for approximately 15 minutes by constant laminar air flow. Novel drying method (ND): drying by shortened drying program for approximately 2.5 minutes in the EWD and then for another 2.5 minutes by an automated drying device using laminar and turbulent airflow (PlasmaTyphoon+). There were no duodenoscopes of Fujifim used in the present trial.
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