Risks

2008-11-27

MEDICAL ERRORS, ENDOSCOPY ACCIDENTS, IATROGENICITY

I.F. Herrmann
Professor, European hospital, Rome, Italy

P. Heeg 
Professor, Institute for Medical Microbiology and Hygiene, University of Tübingen, Medical Centre, Germany

B. Matteja 
Engineer, Product Research and Development, Torino, Italy

H. M. Strahl 
ENT-Consultant, Interdisciplinary Center, Duesseldorf, Germany

H.-P. Werner 
Professor, Centre for Reprocessing (HygCen), Advisor of the Austrian and German Government, Bischofshofen, Austria

W. Boyce 
Professor of Medicine and Radiology, University of South Florida, Tampa, USA

R. Giuli 
Professor of Surgery and Executive Director of OESO, Paris, France

Silent risks and hidden dangers in endoscopy:

what to do?

Abstract: The surface of integrated channel systems is not smooth. The indentations, irregularities and bifurcation inside and at the exits of the channel systems are weak points, where fresh patient material (blood and tissue) remains. Biofilm-formation on the surface is the matrix for microbial growth. Endoscopists must be aware of this risk. The use of 10.000 pixel optics to check the channel system and to control the surface with the microscope should be a requirement in daily practice.

The microbiological analysis alone is not sufficient. The combination of micro-endoscopy with a specified microbiological analysis or better with new techniques based on ATP monitoring or polymerase chain reaction may be the first step towards an improved control of the infection risk. The patients must be informed about these facts as well as the insurance companies in order to calculate the risk of endoscopy. The routine endoscopy with biopsy is the most common procedure and can be performed perfectly with a disposable system. Disposable tube systems connectable to a solid endoscope (without integrated channels) have to be available in order to avoid the risk. We want to ask the responsible companies in this field to collaborate. Endoscopy is an important tool and disposable tube systems at this moment are without any doubt the only safe way.

Comment: This publication is based on the interdisciplinary Workshop: “Standard and/or flexibility in the upper GI endoscopy - Ways to diagnostic and interventional endoscopy”. 9th World Congress of OESO in Monte Carlo (April 6-9th, 2008). Scientific coordination: Robert Giuli.

All participants of this Workshop agreed to constitute an interdisciplinary anti-contamination task force.
Keywords: Endoscope – Contamination

Introduction

Currently, endoscopes are cleaned following the guidelines of national healthcare authorities, endoscopic societies or the recommendations of the companies who produce the endoscopes. In order to clean the integrated channel system brushes and detergent solutions or “washer disinfectors” according to EN ISO 15883 are used, as recommended by the manufacturers. The users feel safe adhering to the guidelines of these organisations. In collaboration with these companies, courses are organized to instruct the users (i.e. the endoscopic team) regarding washing systems. The question is, is this enough? Should we, as responsible users, control the cleanliness and hence the quality of our scopes in a more sophisticated way? And doing it this way can we open new doors to future technologies at the same time?

Background

A systematic review of scientific literature published between 1966 and 2005 reports 70 infection-related incidences (outbreaks). The majority of these cases could have been prevented by adherence of healthcare workers to effective quality control systems [1,2]. However, there is still evidence that endoscopy-associated infections are underreported: for various reasons it is difficult to verify the causal chain and endoscopists may not be very eager to publish cases of nosocomial infections related to endoscopic interventions which they themselves carried out.

The last reported outbreak took place at Las Vegas, Nevada, USA as reported in Las Vegas -Sun 29th of February, 2008 (lit.). The implication is that given the total number of endoscopic procedures which are performed in one hospital over the course of 4 years, there may be up to 40.000 patients who are at risk of infection, including significant blood-borne infections like hepatitis B, hepatitis C and AIDS. The first symptom of these infections is often an unspecific flu-like presentation without specific signs of a virus infection. Often this first symptom may be resolved without the cause being diagnosed. Seven to twenty years after the occurrence of the disease no one will think to ask the question: Did you have an endoscopic procedure 7-20 years ago?

According to the Las Vegas Sun report the investigators discovered that the aspect of the procedure that changed  between patients was the needle for the injection of the anaesthetic drug. For economical reasons the syringe with the anaesthetic remained the same. Is the potential cause of the infection related to aspiration of infected blood into the syringe along with the anaesthetic drug which subsequently is injected into the next patient? Only two patients were infected on the same day, the others on different days. Does this mean that the used syringe containing propofol remains in the refrigerator and is reused until it is empty? There was no mention of whether or not there was an examination of the endoscopes themselves used during the contamination risk-period.

The results of the Hygea-study [3] have demonstrated that after specific instruction to the endoscopic team in professional cleaning, 37% of the endoscopes were still contaminated. The contamination was located in the channel systems, at the Albarran lever and in the connected tube systems. The smooth outer surface is not a problem, because it is easy to clean.

Methods

Microscopic investigations of the endoscope tip and of the entrances of the channels were performed with the Zeissmicroscope OPMI 11. For endoscopic examinations of the inner surface of the integrated channel systems a 10.000 pixel optic, diameter 0.77 mm was used (“naked endoscope”, PolyDiagnost).

Results

The surface of the channel system of new endoscopes is only partially smooth. There are small indentations (Fig. 1), irregularities and a bifurcation at the connections between different parts of the channel. These are the areas, where tissue and blood may be caught and adhere even after cleaning. Investigations of reprocessed endoscopes with integrated channel system regarded as clean demonstrate two types of damage which have infection risks:

a) Fresh tissue or blood particles on the endoscopes may adhere to the surface of the tip and the channel system. These stick more easily on small irregular surface areas or on areas with damaged coating (Fig. 2). This is especially likely in cases when the endoscope is not cleaned immediately after use and is a particular issue with endoscopes having integrated channels.

b) Detergents as well as chemical disinfectants may coagulate, denaturate or precipitate on the surface of the residual blood or tissue within the channel system. However infectious organic material can survive under the surface. With the help of a 10.000 pixel optic it is possible to see the contamination risk in the channel system of a cleaned endoscope. It shows images of dirty channels with yellow and red material and white lines with deposits (Fig. 3). One can see residues of tissue and blood in the channels especially in irregular areas. These areas of indentation, irregularity and bifurcation of the channel system with increased risk of contamination are virtually impossible to clean properly.

c) After using the endoscope frequently or after a long period of time, deposits grow on the surface of the tip and in the suctioning-rinsing and biopsy channels. These deposits do not disappear after cleaning with brushes (Fig. 4). The microscopy of the outer surface of the endoscope tip shows the same infiltration of deposits on the light emission window, as well as at the entrance of the channel system. This infiltration starts with the biofilm on the surface (Fig. 5). Candida cells infiltrate the plastic material. The final deposits consist of fungi, bacteria and amorphous material as shown by electronic microscope scanning of the surface [4].

Discussion

The common reaction to these results is to ask for more manpower, more expertise, and more sophisticated cleaning and disinfecting machines. However these strategies do not address the crucial problem of irregular surfaces in the channel system and the consequences of infiltration of bacteria and fungi into the surface material. Immediate cleaning after use will not eliminate these defects due to indentations, irregularities and bifurcation. What happens for example when the endoscopist requires a new endoscope because of increasing deposits on the endoscope surface? Which hospital will buy a new endoscope as long as the old one is still functioning?

Society as a whole should have a strong interest to find out the reasons for endoscope contamination and to eliminate the risk. Are the companies, which manufacture these endoscopes aware of these facts? This present manuscript gives an inside view of the surface of the integrated channel system, and illustrates that there is a combination of smooth and rough surfaces within channels. Irregularities of the channel surface were expected only in older endoscopes or in endoscopes with a heavy operation factor (i.e. frequent use) [5]. The microendoscopy of the integrated channel system of brand new endoscopes demonstrates that irregularities and indentations are present from the very beginning in a new product and that these can significantly affect the safety of the equipment. To date, there appears to be no reliable procedure to clean these long, thin channels with indentations. Contaminated material may always adhere to these irregularities. Another weak point is how to clean the tiny and hooked exit of the rinsing channel. Biofilm covers the surface after the endoscope is used. The Candida network adheres to the biofilm. Bacteria can then enter this network [4]. The only way to eliminate or at least to slow this process is to clean the endoscope immediately after use. The use of antibiofilm products is recommended [6]. Nevertheless there is a time factor which may limit the use of the endoscope because of the increasing irregularities of the surface [6]. The plastic material of the tip with biofilm on the surface (Fig. 5) presents favourable conditions for the infiltration of Candida cells into the plastic material [4,7,8]. If this occurs the endoscope has to be taken out of use. Experimental work to eliminate these deposits after infiltration to date has not been successful [4]. If the coating of the endoscope becomes defective, the cleaning process becomes more difficult. The rough surface is biased towards contamination. Detergents as well as chemical disinfectants result in a precipitation and a fixation on the surface of the contaminated material [9]. Infected material will survive under the surface. Deposits or crust-formations support this process and amplify the contamination risk. The existing techniques used for culturing are too slow to verify contamination. Improved effectiveness is expected from new techniques based on ATP monitoring or polymerase chain reaction detection [10,11]. Biological tests with germs are not effective for obtaining information about the contamination risk [5,12]. The recovery of test organisms following artificial contamination of the endoscope channels is only 12-18%. This indicates that the fluid used to rinse the channels contains just a small proportion of microorganisms adhering inside the scope. Of course the recovery rate is strongly dependant on the type of the rinsing fluid. These findings reveal the limited value of microbiological checks of reprocessed endoscopes.

At this point in time, micro endoscopy with a 10.000 pixel optic is the relatively safest way to detect contamination. But the lack of visibility of contaminated material in the channel system does not allow us to conclude that the channel system is clean. The recommended wash disinfectors have their own problems:

• cross contamination between endoscopes and washer disinfectors may happen;
• the transmission of microorganisms to other endoscopes can take place;
• the risk of cross-infections within one hospital exists;
• contamination as a problem of importing is possible [6].

Resulting strategies to avoid such problems are:

• multiple endoscopes should not be disinfected in the same washer disinfector cycle;
• auto disinfection of washer disinfectors should be performed after every disinfection cycle of a washer disinfector; this practice will be very expensive; The solution is twofold: to use endoscopes without integrated channel systems connected with disposable channel systems whenever possible (Fig. 6) [13] and to perform the endoscopy transnasally without  intravenous sedation (Fig. 7).

The width of nasal passage of an adult is sufficient to allow the passage of two tubes up to 3.7 mm in total diameter. They would be positioned one above the other (7.4 mm endoscope + disposable tube). Endoscopes without integrated channel systems are smooth and easy to clean. The disposable tube system is attached to the endoscope and has a suctioning-rinsing and working channel. The use of nose-drops for decongestion and local anaesthesia (e.g. drops of oxybuprocain 1-2%) especially in allergic subjects are useful. The endoscopy is performed without sedation and with the patient in sitting position in order to analyse function. The endoscope passes the upper sphincter while the patient is drinking a sip of clear water. For air inflation the patient changes to recumbent position. Biopsies can be taken from the duodenum, stomach and oesophagus as per usual.

The advantages of this method are:

• There is no risk of drug-associated, intravenous infection, because no sedation is used;
• There is no risk of contamination with disposable channel systems;
• The endoscopic technique allows examination of the function of the digestive tract and provides an opportunity to take reflux (gas and liquid) samples under visual control [14];
• The inversion of the endoscope in the esophagus and duodenum and the measurement of size and shape of a pathologic change are now possible;
• This new technique permits intervention procedures to be performed at the same time
• It is more cost-effective: the patient is able to function normally immediately after the endoscopy; he can drive his car or can return to work;
• Less assistance is necessary, because the patient remains able to collaborate;
• There is a reduction of costs to the public healthcare, to the economy and to the patients due to the resulting decrease of the cost/efficiency-index with the reduction of the infection risks.

The disadvantages are:

• The endoscopist must be flexible enough to change his / her traditional method to use a new technique;
• There may be a possible change of current target markets for the companies who manufacture endoscopes. The more desirable route would be to start with countries which have a high incidence of AIDS and hepatitis B and C. This would allow us to specify the adaptations without commercial bias.
• The disposable system has no Albarran lever; the endoscopy of the ductus choledochus and ductus pancreaticus has not been possible until now. In these cases the safest way to solve this particular problem is to establish control mechanisms such as:

a) the endoscopy of the integrated channel system could use a mini-scope as a procedure of routine;

b) the bacteriological analysis of the channel system could be improved. Bacteriological analyses of reprocessed endoscopes however are not sufficient [6].

Validation of cleaning and disinfection processes, not merely checking the end product, is essential. Perspectives In countries with high incidence of AIDS, hepatitis B and C and where there are limited resources and financial means, it would be unrealistic to purchase and maintain equipment such as automatic washer disinfectors. The  majority of the flexible eso-gastro-duodenoscopies without or with biopsy are performed with integrated, and most likely,  contaminated channel systems. For these countries, a disposable system may significantly reduce the infection risk and subsequently morbidity and mortality in terms of bloodtransmitted infectious diseases.

The disposable system opens new scientific possibilities.Samples of gas, liquid etc. from the duodenum, stomach and oesophagus could then be taken under direct view. This procedure could provide us, for example, with important information about gastric function and metabolism. We know this from the extended endoscopy of up to 8 hours during investigation of the stomach function during digestion [14]. Observation of the gastric function has opened a totally new insight into the gastric function and metabolism. 10

 Print this page | Diese Seite drucken

No Comments

No comments yet.

RSS feed for comments on this post.

Sorry, the comment form is closed at this time.