Macro Problem: Nano Solution
Small molecules help solve a big problem: sponges left behind after surgery
By Dr. Sushil Bhatia
Contributing Editor
Problem
In a report entitled "X-Ray Detectable Surgical Sponges" from 1980, the following was reported by Hazard [Health Devices, Dec. 1980; 10(2): 52]:
Member hospitals have reported an inability to radio graphically detect sponges labeled as "X-ray detectable" or "radiopaque" following loss in patients during surgery. The problem is most acute with small sponges used in surgery of the head and spine, since their presence is frequently masked by nearby bone.
These surgical sponges can be as small as 1/4" square. They are manufactured with either a small radiopaque insert (typically a thin flexible strip about 2 mm wide) sewn or melted into the material, or they are impregnated with a radiopaque substance such as barium sulfate. While the insert tends to be more radiopaque than barium sulfate impregnation, it represents a smaller target to locate.
The sponges can be readily detected if radio graphed through tissue such as muscle or fat that is less dense than the radiopaque insert. However, if the x-rays must also pass through denser tissue such as bone, it is likely that the sponge will be masked and difficult or impossible to detect with a single radiographic view. Since the loss of these small sponges is uncommon, their detection by radiography is not a routine procedure and the limits of their radiopacity may not be widely known.
Standards activities, underway for several years, are seeking to define a required level of radiopacity and develop a standardized test method specifying exposure limits, film type, aluminum mask thickness, and radiograph viewing conditions.
It has been reported that surgical teams accidentally leave clamps, sponges, and other tools inside about 1,500 patients nationwide each year, according to the biggest study of the problem yet. The mistakes largely result not from surgeon fatigue, but from the stress arising from emergencies or complications discovered on the operating table.
According to a study published in The New England Journal of Medicine (Volume 348:229-235, January 16, 2003 No.3, Atul A. Gawande et.al), error in medicine is common and may cause harm; however, isolating the factors underlying specific types of errors has proved to be a formidable task. One persistent but poorly understood error is leaving sponges or instruments inside patients who undergo surgery. The retention of sponges and instruments is considered by many to be avoidable, and when it occurs, it can attract wide, critical press coverage. Yet these errors persist. Although the incidence has not been determined, estimates suggest that such errors occur in 1 of every 1,000 to 1,500 intra-abdominal operations.
There is great uncertainty about why these incidents occur and how to prevent them. The standards of the Association of Operating Room Nurses have long required that only sponges detectable on radiography be used and that they be counted once at the start and twice at the conclusion of all surgical procedures. The standards also recommend that instruments be counted in all cases involving an open cavity. If a count is incorrect—that is, not all materials are accounted for—then radiography or manual re-exploration is to be performed. In published case series, some incidents appear to result from a failure to adhere to these standards; however, in the majority of cases, foreign bodies go undetected despite proper procedures.
In some cases described in other medical journals, surgical sponges (which are actually gauze pads) left in patients became embedded in tissue and were mistaken for tumors. As a result, patients had parts of their intestines removed.
Dr. Gawande and his colleagues estimate that sponges or instruments are left behind at least 1,500 times a year in the U.S.—a tiny fraction of the total operations, which exceed 28 million. That works out to about one case a year for a typical large hospital. But, the authors note, the cases "attract wide, critical press coverage," and patients often sue. In Massachusetts cases that the researchers studied, patients won an average of about $53,000.
The profession has coined a word for a left-behind surgical sponge: gossypiboma, from the Latin word gossypium for cotton and the Swahili boma for "place of concealment." Sponges can disappear inside a patient even if they have long strings with rings attached to hang outside the incision and help doctors keep track of them, Dr. Gawande said.
"No major body cavity was spared," the researchers wrote, noting that 54 percent of the foreign bodies were left in the abdomen or pelvis, 22 percent in the vagina, 7.4 percent in the chest, and 17 percent in other places like the spinal canal, face, brain, and extremities. In a few cases, the forgotten object was found by the first day after surgery, but some were left in for years. The median interval was 21 days.
Three factors did stand out. Compared with patients who did not have objects left inside them, those who did were nine times as likely to have had emergency surgery and four times as likely to have had an unexpected change in their procedure. In both situations, the authors said, disorganization may increase, making it harder to keep track of sponges and equipment. The third factor was size: large people were more likely to have objects left behind than lean people, simply because there is more room for losing things.
To prevent the mishaps, Dr. Gawande and the other authors of the article suggested that surgical teams count sponges before and after every operation, and count instruments whenever the surgery involved an open cavity. Their study found that a third of the time, records showed that such counts had not been done. At many hospitals, sponges are routinely counted, but instruments are not. Or they are counted only in some operations.
In situations known to be high risk for losing sponges or tools—emergency operations, procedural changes, very large patients—he and his fellow authors suggest that X-rays be taken in the operating room to look for hidden objects before the patient is sewn up. In the future, Dr. Gawande said, it may be possible to make instruments and sponges with gadgets that would set off an alarm in response to a probe or scanner, similar to the clothing tags that set off alarms at department store exits. In spite of the passage of time, the loss of sponges and tools during surgery continues to be a big problem. Possible solutions may benefit from RFID technology.
Solution
In the past as stated above, different methods have been used, but rather unsuccessfully. Due to chaos in the operating room or to confusion, it is not always possible to think straight and follow all the procedures, especially since the well being of the patient is the number one priority. There are two possible solutions:
1. Use RFID technology by embedding a RFID chip in each sponge—a definitely expensive proposition.
2. Using nanotechnology materials of very small, particle size embedded/mixed with sponges so that they can be detected with a reader like RFID readers. This method will use two readers (before and after). The readers will provide a detectable signal as well as counter and will be able to read from a distance with the need for each individual item being separately scanned. They will be able to scan through anything (blood, septum, etc.) that a sponge will generally be absorbing.
The readers can be mounted in the roof of the operating room, which will also point out where the sponges and tools are. The readers will differentiate between the clean and dirty ones so that they can be tracked well as to their whereabouts.
This is similar to the studies being done for detection of cancer where nanoshells (invented by Dr. Naomi Halas) are being used to interact with light in unusual ways. Nanoshells are tiny balls of sand surrounded by a layer of gold. By varying the thicknesses of the sand center and the gold layering, researchers can change the optical properties of the nanoshells, making them absorb light of a chosen wavelength. The study has shown that strong scattering of light by nanoshells provides an optical signal used to detect cancer cells. At certain wavelengths of light, they "light up" the location of the cancer cells. These techniques can be readily extended to other type of diseases or commercial applications with known surface markers. Nanoshells when used with sponges will help detect their location, whether they are accidentally left inside the body or outside where they will be helpful to detect and count the sponges using the readers installed in the operating room.
Benefits of this approach
The above approach can be extended to the counting of sponges and tools in the operating room where different wavelengths of light can be used to detect used and unused sponges and tools. The two readers fitted in the roof of the operating room can keep track of the disposal of the pre-counted sponges and tools brought into the operating room— one will read, detect, and record unused and clean items, where as the other will read, detect, and record the used (dirty) items. Because of the fact that they will detect and record automatically, it will eliminate the human error factor, especially when everyone is under a lot of stress.
Dr. Sushil Bhatia is president of JMD Manufacturing Inc. and also serves as executive-in-residence at Suffolk University, Boston, where he teaches courses on global innovation and strategic management. Bhatia has been featured in publications such as The Wall Street Journal and The Boston Globe for his inventions. Bhatia received his Ph.D in chemistry from Universite de Liege (Belgium) and MBA from Suffolk University. Dr. Sanjay Sarma, a co-founder of the AutoID center at MIT, also contributed to this article.
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