Mistake-Proofing the Design of Health Care Processes

Chapter 6: Medical and Nonmedical Examples: Differences and Similarities

Introduction

Despite the different domains in which mistake-proofing is employed, actual devices often are not very different. This chapter provides 19 pairs of examples. Each medical example is paired with an example from industry or everyday life. The examples also suggest that many solutions for medical mistake-proofing have already been implemented in other industries and only need to be adapted, or directly imported, for use in medical environments.

Maurer, et al.¹ pose the question "Are industry-based safety initiatives relevant to medicine?" Their article argues for an affirmative response:

The fundamental concepts of these quality programs, [e.g., Six Sigma], although initially designed to improve manufacturing quality and efficiency, can be effectively applied to service-based activities such as medical care. In one case, implementing an industry-based quality program in the medical department of a large manufacturing concern initiated improvements and changes to the medical care process.

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Example Pair 6.1—Color Coded Wires

Medical Application

In Figure 6.1, each monitor lead is color-coded so that it can be correctly placed on the patient and hooked to the same color-coded outlet on the machine.

Comparable Nonmedical Application

Color-coding is a weak but widely used mistake-proofing method shown in Figure 6.2 on the back of a computer. Depending on the application, color-coding can be very effective, despite its inability to stop the process.

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Example Pair 6.2—Automatic Wheelchair Brakes

Medical Application

Xiang, Chany, and Smith² reported that in 2003, more than 100,000 wheelchair-related injuries were seen and treated in US emergency rooms—twice the number reported in 1991. The authors also reported that in all age groups of wheelchair users, tipping over and falling accounted for 65 percent to 80 percent of injuries. Brechtelsbauer and Louie³ reported on a study of incidents involving wheelchair use in long-term care and found that most injuries were a result of attempts by residents to self-transfer into or out of the wheelchair.

The wheelchair in Figure 6.3 is equipped with a device that automatically locks the wheelchair when no one is sitting in it. When empty, it can only be moved when the unlocking lever on the handle is used.

Comparable Nonmedical Application

Some applications of medical mistake-proofing do not differ from nonmedical applications. Many riding mowers have a "dead-man's switch" on the seat. When the rider gets out of the seat for any reason, the engine turns off. The mower is equipped with an electronic sensor on the bottom of the seat (Figure 6.4). Of course, employing electronics would be an added system for non-electric wheelchairs. The purely mechanical approach could be preferred because of its simplicity.

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Example Pair 6.3—Picking Up the Right Product, Part I

Medical Application

The Pyxis system controls access to medications. The drawers are locked and inaccessible unless the proper verification process is completed. The user enters patient and order information via the keyboard or the barcode reader. The information is processed, and only the correct drawer opens to allow access to the prescribed drug. The supply cabinet in Figure 6.5 features a pick-to-light system. Green lights indicate the shelf on which the selected item resides.

Comparable Nonmedical Application

Comparable systems exist in industry. The bins in Figure 6.6 are equipped with pick-to-light systems. These systems have a computer-controlled system of lights that indicate from which bin items are to be removed. Some are equipped with an infrared sensor that sounds a buzzer if an item is selected from the wrong bin.

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Example Pair 6.4—Picking Up the Right Product, Part II

Medical Application

Figure 6.7 shows the interior of a robotic pharmacy. The inventory-picking robot increases the accuracy of picking and the speed/efficiency of the operation. Comparable systems, called Automated Storage and Retrieval Systems (ASRS), are used extensively in industrial settings.

Comparable Nonmedical Application

The Oviatt Library at California State University at Northridge features an ASRS in its East Wing (Figure 6.8). The ASRS employs 13,260 steel bins that measure 2 feet by 4 feet. Infrequently used books and older periodicals are stored in the 8,000 sq. ft wing, which has a ceiling height of 40 feet. Bar codes attached to books and periodicals are mapped to their bin locations in the ASRS system. Materials are retrieved using a computerized lift that is guided by rails at the top and bottom.

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Example Pair 6.5—Close the Door to Start

Medical Application

The automatic tissue processor in Figure 6.9 is equipped with an alarm to verify that the door of the processor has been properly closed before processing begins. Processing will be halted if the door is opened for any reason.

Comparable Nonmedical Application

At times, mistake-proofing for a medical environment is not very different from existing mistake-proofing applications in everyday life. For decades, clothes dryers have been designed to stop operating when the door is opened (Figure 6.10).

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Example Pair 6.6—Push to Go

Medical Application

The portable x-ray machine in Figure 6.11 is equipped with a brake that disengages when a user pushes down on the handle. The mechanism prevents the x-ray machine from moving unless it is being pushed.

Successful mistake-proofing requires attention to many details

Comparable Nonmedical Application

The portable x-ray machine in Figure 6.11 and the luggage cart in Figure 6.12 employ the same approach to eliminate errors. The luggage cart requires the user to depress the bar in order to disengage the cart's brake. The shaved ice machine in Figure 6.13 requires the lid to the shaving chamber to be closed and depressed in order for the machine to operate.

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Example Pair 6.7—Collision Prevention

Medical Application

The bumper switch stops a portable x-ray machine if the front bumper comes into contact with an object (Figure 6.14). The bumper is easily pushed in so that the slightest contact causes the portable unit to stop immediately.

Comparable Nonmedical Application

In robotic manufacturing systems, material is moved using automated guided vehicle systems (Figure 6.15). The automated guided vehicles are equipped with bumpers that stop the vehicle if they contact anything in their path. It is the bumpers, not neural networks, that enable these special purpose robots to adhere to the first law of robotics: "A robot may not injure a human being, or, through inaction, allow a human being to come to harm."⁴

Similar approaches are used on jetways at major airports. Bumpers stop the jetway if it comes into contact with anything near the wheels.

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Example Pair 6.8—What Goes In Must Not Come Out

Medical Application

The sharps container in Figure 6.16 ensures that used sharps (needles) cannot be reached and removed after they are deposited. The used sharp is placed on the back part of the lid, which is then lifted to dump the sharp into the container. The lid's design makes it impossible to access the used sharps. This example is similar to the darkroom door example (Chapter 5, Figure 5.1).

Comparable Nonmedical Application

The same techniques for preventing individuals from gaining access to deposited items are used in library book returns (Figure 6.17) and bank night depositories (Figure 6.18).

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Example Pair 6.9—Two Hands Required

Medical Application

As a safety mechanism, all defibrillators require the activation of two separate buttons, held by one operator, to trigger discharge of an electrical current across the thorax of patients in ventricular fibrillation (Figure 6.19). The two-button feature reduces the risk of accidental discharge or misplaced electrical shock.

Comparable Nonmedical Application

The punch press in Figure 6.20 was made in the United States and exported to a factory in Asia. The American manufacturer assumed that one person would operate the machine. It has two switches, one for each of the worker's hands. Multiple switches are very common on manufacturing machinery. They provide the same safeguard as the buttons on the defibrillator in Figure 6.19.

In countries with low wages and lax occupational safety laws, getting the most out of this machine means using six hands instead of two. One bad judgment or lapse of attention can result in the maiming of a worker and the end of a productive working life. Medicine is not very different. One bad judgment or lapse of attention can maim a patient or end the career of a doctor or nurse. Neither result is acceptable.

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Example Pair 6.10—How Information Is Presented Matters

Medical Application

How information is displayed makes all the difference in its utility. Clipboards filled with papers (Figure 6.21) are much more effective at providing an audit trail than they are at communicating the status of the patient or how the process should proceed.

The use of electronic medical records enables information to be reformatted in ways that are more readily understandable. Powsner and Tufte⁵ propose medical charting software that renders years of data more easily understandable (Figure 6.22). Go to Chapter 7, Example 7.18, for a larger image of the graphic medical chart.

Comparable Nonmedical Application

The formatting of information also matters outside of medicine. Figures 6.23 and 6.24 document the performance of a complex machine being tested before it is shipped to a customer. The company found that most of the critical information on which decisions were based could be contained on one summary page (Figure 6.24). Reportedly, the result was that decisions were made more quickly, and use of the information increased. Managers also found that the trends on the one-page graph (Figure 6.25) were easier to spot than when presented on a graph that was "three cubicles long" and folded every 11 inches (Figure 6.26).

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Example Pair 6.11—Tooling: Jigs and Fixtures

While the idea of using jigs and fixtures in health care may seem distasteful, there are numerous examples of devices that allow the body to be positioned in ways that facilitate good care. In many cases, these devices are used solely to increase a patient's comfort.

Medical Application

The CT scan head holder in Figure 6.27 keeps the patient's head in the correct position during a CT scan, which is critical to an accurate reading.

The immobilizer (Figure 6.28) has been in use for 40 years. Designed by a technician who had many problems with positioning infants and children, it securely restrains infants during imaging.

Beds used in maternity wards are equipped with stirrups (Figure 6.29) to allow expectant mothers to be positioned correctly and as comfortably as possible under the circumstances.

Comparable Nonmedical Application

Figures 6.30 and 6.31 depict a fixture for holding parts in the correct orientation during fabrication.

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Example Pair 6.12—Lock-Outs

Medical Application

An electromechanical door lock system on the lab centrifuge in Figure 6.32, together with a manual lock, prevents run initiation unless the door is closed and latched. When a run is in progress, the door locks automatically and can be opened only when the power is on, the rotor is virtually stopped (spinning less than 40 rpm), and the lock is in the unlocked position. An LED (light emitting diode) on the "open door" key lights up when the door can be opened.

Comparable Nonmedical Application

The centrifuge in Figure 6.33 is used to stress test ceramic semiconductor packages to ensure the integrity of the hermetic seal. Heavy steel wheels full of parts are loaded into the machine. The lid is closed and locked before starting. After the machine has started to spin, the cover is locked and cannot be opened until the speed of rotation approaches zero.

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Example Pair 6.13—Visual Indication of Settings

Medical Application

Michael Westley, medical director of critical care and respiratory therapy at Virginia Mason Hospital in Seattle, Washington, reported that:

The hospital was able to reduce cases of ventilator-associated pneumonia (VAP) from 30 in 2002 to 5 in 2004. Costs associated with each case of VAP ranged from $5,000 to $40,000. Doctors and nurses reduced the number of cases by "reliably doing boring things." The "boring things" included frequent hand washing by doctors and nurses and keeping patients' heads elevated.⁶

The Mississippi delegation to the Patient Safety Improvement Corps (PSIC) also focused on reducing VAP rates. One action they took was to ensure that patients' beds were raised to an angle of at least 30°. To facilitate "reliably doing boring things," Darla Belt, an RN on the team, felt that it was important to be able to determine whether the bed was at the correct angle from outside the room in the ICU. Her solution was to apply a label to the bed to indicate the correct angle (Figure 6.34). She reports that staff members have become accustomed to the label's position. Spotting it from the doorway, they no longer have to walk into the room to check the bed's angle, realizing that a flat or vertical sign is indicative of a less than ideally positioned bed. Consequently, an out of place sign is immediately noticeable to the staff. Now, when they see a bed without a gauge on its railing indicating the angle of the bed, they can judge the correct angle of the bed fairly accurately.⁷

Figure 6.35 could be seen as a slight improvement: staff mount the label at 30° so that it is level when the bed is at the correct angle. Staff will quickly become accustomed to looking at this angle and judging whether or not it is correct.

Comparable Nonmedical Application

The label in Figures 6.36 and 6.37 is attached to a vibrator bowl (Figure 6.38) that is used to prepare steel tools for chroming. The label helps workers determine if the bowl is operating correctly. It is difficult to tell from the photograph, but in Figure 6.37, the lines labeled 60 and 70 appear to be less blurry. This indicates that the lead angle is between 60° and 70°. The series of circles running horizontally below the fan shaped figure show vibration amplitude. At the circle labeled 2, the two circles created by the vibration do not touch. At 7, the two circles overlap. At 3.5, the circles just touch. This means that the amplitude is 3.5 mm. The label enables anyone to determine how well the bowl is operating.

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Example Pair 6.14—Knowledge in the World Equals Knowledge on the Pill

Medical Application

Many pharmaceutical companies use color-coding and information printed on the product (Figure 6.39) to inform consumers of the medication and dosage.

Comparable Nonmedical Application

A color-coding scheme is used for electronic resistors to communicate tolerances and electrical properties from .01 to 10,000,000 ohms (Figure 6.40).

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Example Pair 6.15—Don't Reinvent the Wheel, Part I

Medical Application

Often, there is no difference between medical and nonmedical applications. In the case of the restaurant pager, the medical application is an off-the-shelf application taken directly from the restaurant industry, not a separate invention.

In St. Joseph's Hospital in West Bend, IL, pagers are distributed to patients in the hospital waiting room (Figure 6.41).

Comparable Nonmedical Application

Staff members saw restaurant pagers (Figure 6.42) and bought them, then began using them to improve patient and health care worker satisfaction.

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Example Pair 6.16—Coverage Must Be Complete

Medical Application

Chlorhexidine has been shown to be more effective than iodine for the prevention of intravascular catheter-related infections.⁸ Yet, its adoption has not been as rapid as some might expect. One explanation is that chlorhexidine is clear (Figure 6.43). It does not leave iodine's telltale, burnt orange stain. The stain gives a visual indication of where it has been applied, and whether or not the coverage is satisfactory. A solution is to add blue-green tint (Figures 6.44 and 6.45) to chlorhexidine for easier visualization.

Comparable Nonmedical Application

Ceilings are typically white. The application of a fresh coat of white paint on a surface that is already white makes it difficult to determine where spots have been missed, and whether an adequate amount of paint has been applied for good coverage. A solution is to add pink tint for easier visualization. The specially formulated ceiling paint in Figure 6.46 goes on pink but dries white.

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Example Pair 6.17—Wheelie Bars

Medical Application

The anti-tip wheels mounted to the back of a wheelchair (Figures 6.47 and 6.48) play a very important role. They keep the chair from tipping backward. They also allow the rear wheel to be mounted further forward without the feel of tipping backward. This reduces the weight on the small front wheels, allowing them to turn and roll up and over small obstacles more easily.

Comparable Nonmedical Application

A drag racing motorcycle (Figure 6.49) is equipped with a wheelie bar that keeps its front wheel from coming up too high and prevents the driver from losing control.

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Example Pair 6.18—Don't Reinvent the Wheel, Part II

Medical Application

Figure 6.50 illustrates another adaptation of a solution used in retail stores and libraries. Richard Chole, M.D., Ph.D., noted that, even with the "sign your site" policy in place, wrong-site errors (where surgery is performed on a site other than the intended one) still occur and are attributed to one primary cause: the surgical site was not marked. After noting the antitheft chips attached to items sold at a large hardware chain store last summer, he invented a wristband embedded with a miniature, disposable microchip, and a marker pen with a specialized sticker that deactivates the chip.^9,10 After consulting with the patient or the patient's family, a staff member marks the patient's surgical site, then removes the sticker from the pen and places it on the patient's wristband to deactivate the chip.

If these steps are not followed, the wristband will set off a detector placed in the hallway between the preoperative area and the operating suite. The detector can be set up to give a visual or auditory signal that alerts hospital personnel.

Comparable Nonmedical Application

Libraries have enacted comparable measures to reduce book thefts. A narrow strip of magnetic material (Figure 6.51) is affixed to each library book. Sensors are placed in front of the exit door (Figure 6.52). An alarm goes off if the book has not been desensitized at the checkout counter.

Figures 6.53 and 6.54 illustrate alternate configurations. In Figure 6.53, a metallic layer of the sticker desensitizes the article for removal from a library. In Figure 6.54, a commercial product has a sensor strip attached to discourage and catch shoplifters. All three approaches are similar. The advantage of the magnetic material in Figure 6.51 is that it is much harder to find and, therefore, harder to remove.

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Example Pair 6.19—Color-Coded Lights

Medical Application

In an effort to make system status obvious even in lowlight situations, the intravenous (IV) pole in Figure 6.55 is equipped with light-emitting diodes (LEDs) that illuminate the bags of fluid. Colored plastic inserts change the color of the light shining on each channel so that each bag is uniquely identified. Correspondingly colored cyalume lights and stickers are attached to each IV tube (Figure 6.56). This enables the tubing at one end to be more reliably associated with its contents in the IV bag at the other end.

Comparable Nonmedical Application

The small electronic device on the toilet in Figure 6.57 detects user movement and turns on one of two LED lights. When the red light turns on, the toilet seat is in the up position. A green light indicates that the seat is down.

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A Future Mistake-Proofing Wish List

Medical Application—Rolling Bed Table

A participant attending the Patient Safety Improvement Corps, sponsored by the Department of Veterans Affairs (VA) and the Agency for Healthcare Research and Quality (AHRQ), suggested the need for an overbed table that would not roll when patients used it to steady themselves. No one present knew of such a product. The technology involved to develop such a product, however, could be relatively simple.

Comparable Nonmedical Application

The step stool in Figure 6.58 rolls freely until someone steps on it. The user's weight presses the rim of the stool firmly against the ground so that it will not roll. Perhaps this technology could be applied to solve the hazard of rolling overbed tables. Experimentation of this sort—using creativity to apply existing technology to new problems—has proven to be worthwhile in several examples discussed in this chapter.

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References

1. Maurer KF, Maurer JR, Peltier E, Savo P, et al. Are industry-based safety initiatives relevant to medicine? Focus on Patient Safety 2001;4(4):1-3.

2. Xiang H, Chany AM, Smith GA, Wheelchair-related injuries treated in US emergency departments. Inj Prev 2006;12(1:)8-11

3. Brechtelsbauer DA, Louie A. Wheelchair use among long-term care residents. Ann Long-Term Care 1999; 7(6):213-20.

4. Asimov I. I, Robot. New York: Signet Books; 1956.

5. Powsner SM, Tufte ER. Graphical summary of patient status. Lancet 1994;344(8919):386-9.

6. Connolly C. Toyota assembly line inspires improvements at hospital. Washington Post June 3, 2005; p. A01.

7. Belt D. Personal communication. June 14, 2005.

8. Chaiyakunapruk N, Veenstra DL, Lipsky BA, et al. Vascular catheter site care: the clinical and economic benefits of chlorhexidine compared with povidone iodine. Clin Infect Dis. 2003; 37(6):764-71.

9. Pahl K. Physician invents smart wristband to prevent wrong-site surgery. Barnes Jewish Hospital, Washington University in St. Louis. BJC Today 2005 August 22.

10. Ericson, G. Smart wristband designed to prevent wrongsite surgery. Washington University in St. Louis, School of Medicine; press release, 2005; Aug 9. Available at: http://mednews.wustl.edu/news/page/normal/5547.html. Accessed June 2007.

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