Rigid endoscopes—ensuring quality: before use and after repair

AORN Journal,  July, 2004  by Cynthia Spry,  Dennis C. Leiner

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The preoperative patient assessment has been conducted, the anesthesia care provider and surgeon are standing by, the instruments and equipment have been checked, and the OR has been readied for a laparoscopic cholecystectomy. The incision is made, and the surgeon inserts the laparoscope--only to discover that the image is not clear. The circulating nurse obtains another endoscope, and the faulty one is sent for repair.

This scene is repeated many times each day in ORs throughout the country. Judging by the number of endoscope repair companies in existence, endoscope repair is big business. Typically, as the volume of minimally invasive surgical procedures at a facility increases, so do the costs for endoscope repairs. In some facilities, the budget for endoscope repairs may exceed the budget for new purchases, and endoscope failure often is a direct result of improper repair.

HARSH CONDITIONS

Rigid endoscopes are fragile devices that routinely are subjected to harsh conditions. They are washed in automated systems at temperatures of 90[degrees]C (194[degrees]F) and higher. They may be packaged in metal trays with other instruments that can cause impact damage during transport or placement in the sterilizer. If endoscopes can be sterilized, they routinely are sterilized at temperatures of 134[degrees]C (273.2[degrees]F).

An endoscope used during only one procedure typically will be handled by a minimum of six people, including the scrub person; circulating nurse; surgeon; and personnel responsible for decontamination, prep and pack, and transport. Considering the number of procedures a single endoscope may be used for, the conditions of washing and sterilization, and the number and variety of people who handle the endoscope, it is easy to see how damage can occur.

PREPROCEDURE CHECKS

To prevent discovery of damage after a surgical procedure has started, central service personnel should inspect and test an endoscope before it is packaged for sterilization. The shaft is inspected for dents, which can indicate a broken rod. The lens and tip are checked for scratches, and the tip is checked for chips that may have resulted from a collision with a shaver or other instrument. Looking through the eyepiece at a light source may reveal a cloudy lens, which could indicate a leak. Finally, the endoscope may be directed at an object across the room or at a piece of paper with writing on it to determine resolution quality. If the object or words appear clear, the resolution is considered satisfactory.

The scrub person should perform additional testing on the endoscope during setup for a procedure. If an object appears clear when viewed through the endoscope, the endoscope is deemed satisfactory. These tests are imprecise; therefore, it still is possible that a surgeon will reject an endoscope during a procedure.

Additionally, a scrub person may assume a repair was satisfactory and therefore may not perform a test on a repaired endoscope, so it is not uncommon for a repaired endoscope to be rejected after several uses. These endoscopes may rail when lenses, prisms, or lens spacings inside the endoscope are not replaced with original parts. When a repair company does not have original parts, it may make modifications that affect image qualify. A quality control system for endoscope testing at the time of purchase and after repair will detect these problems.

QUALITY TESTING

There are some simple tests that can be used to test endoscope quality. Understanding what can go wrong with endoscopes from an optical standpoint and how to test them can help staff members detect problems before rather than during surgery; evaluate repairs; and instruct repair companies on the required service (Table 1).

Although the best tests of optical quality are conducted using complex and expansive optical and computer hardware, there are some simple tests that can be performed in the health care facility that will provide usable measurements of endoscope function. The OR manager can develop a checklist of measurements that should be performed before each procedure and a more complete list of measurements to be performed with new or repaired endoscopes. Only image resolution and fiber optic illumination need to be measured before each procedure. All measurements should be performed to establish a baseline for new endoscopes and to evaluate the quality of repairs. A sample checklist is provided in Figure 1.

OPTICAL RESOLUTION. Optical resolution--a measurement of image clarity--is the most important parameter to measure. It tells both the size of the smallest object that can be distinguished and the overall contrast of the image. Engineers measure optical resolution using a parameter called modular transfer function, which can be measured only with complex instruments. An estimate of resolution, however, can be obtained using simple charts developed by the US Air Force. Figure 2 shows a chart consisting of a series of three equally spaced black rectangles that is customized for use with an endoscope's circular field of view. The numbers next to each of the bars represent the number of bars that would fit across the field of view if bars were repeated over the entire image. A larger number of bars means that more detail can be distinguished in the image. A larger, high-resolution version of this chart is available online at http://www. lighthouseoptics.com/chart.