Swallowed magnets: An attraction that can be fatal
- Swallowed magnets: An attraction that can be fatal
- Flat colorectal lesions are harder to spot than polyps
- Gecko toes inspire new surgical bandages
- "We've got a bleeder!"
Swallowed magnets: An attraction that can be fatal
Magnetic building sets are popular among grade-school children, but parents may want to refrain from buying them for their youngsters. Between 2006 and 2008, the US Consumer Product Safety Commission (CPSC) recalled more than 4 million toys that contained magnets small enough for a child to aspirate or ingest. Although most magnetic building sets with small parts are recommended only for children 6 years and older, the pieces frequently find their way into the hands?and mouths?of much younger children. Also, many parents assume incorrectly that children have outgrown the temptation to put small toys in their mouths by age 6. The CPSC reports that 10 out of 33 known cases of magnet ingestion involved children older than 6 years. In 2004, Dr. Alan E. Oestreich wrote to Radiology about a 12-year-old autistic patient at Cincinnati Children's Hospital Medical Center who swallowed several magnets and suffered small bowel necrosis and perforation. In the March 2006 issue of Surgical Rounds, Dr. Scott Reed reported the case of an 11-year-old boy who had similar injuries after swallowing several nuts and bolts along with a 1-cm magnet.
While surgeons have long been aware of the risks posed to children who consume magnets, the subject attracted renewed media attention following a February 2008 article in the Archives of Pediatric and Adolescent Medicine. Four-year-old Braden Eberle underwent laparoscopic surgery last spring to remove two magnets, each barely larger than a pea, lodged in his intestine. Eberle's surgeon, Dr. Sanjeev Dutta, reported that the boy's intestine showed areas of necrosis and perforation.
Today's toy magnets, made of inexpensive rare-earth elements, are far more powerful than the ones most adults remember playing with as kids. When a child swallows multiple magnets or ingests a magnet in conjunction with other metal bits (such as nuts and bolts), the pieces attract one another through the thin lining of the bowel wall. The body lacks sufficient strength to separate and expel the objects. As in Eberle's case, the magnets can pinch tissues together so tightly that the blood supply is restricted, resulting in tissue death and erosion. Magnet ingestion has been known to cause perforation, volvulus, bowel obstruction, ulceration, peritonitis, embedded magnets in the stomach lining, and, in the case of one toddler, death.
Parents often attribute complaints of abdominal pain to gastroenteritis or other mild stomach ailments, which can delay diagnosis and treatment. Dr. Reed warns surgeons to be alert for "nonspecific symptoms, such as excessive salivation, nausea, vomiting, or respiratory difficulty." Dr. Julie Gilchrist of the Centers for Disease Control and Prevention's Division of Unintentional Injury Prevention advises surgeons to consider any foreign object observed on a child's radiograph as a possible magnet and act accordingly. Note that when magnetic materials adhere to one another, they can appear as a singular object on radiographs. If a child is suspected of having swallowed or inhaled a magnet, magnetic resonance imaging should never be used, for obvious reasons, Dr. Oestreich warns.
Parents need to be made aware of the dangers of tiny magnets, and surgeons need to keep magnet ingestion in mind when evaluating children for abdominal pain.
Flat colorectal lesions are harder to spot than polyps
Just when new guidelines suggest that doctors consider using virtual colonoscopy to screen patients for colorectal cancer, a recent study in the Journal of the American Medical Association (JAMA) calls this method's efficacy into question. While virtual colonoscopy readily detects the mushroom-shaped colon polyps that can be found in up to 30% of adults, it cannot detect nonpolypoid colorectal neoplasms (NP-CRNs). NP-CRNs are flat, depressed, or slightly raised with a depressed center. They may exhibit discoloration or redness but are often indistinguishable from healthy mucosa. Roy M. Soetikno of the Veterans Affairs Palo Alto Health Care System, the study's lead author, describes them as looking like "a pancake at the bottom of a pan." NP-CRNs are difficult to visualize even when using traditional colonoscopy, especially if patients fail to follow prescribed bowel preparation protocols before undergoing the procedure.
The JAMA study examined 1,819 military veterans who underwent elective colonoscopy. Patients were mostly men, with an average age of 64 years. The study population was divided equally into three groups: screening, surveillance (those with a personal or family history of colorectal adenomas or carcinoma), and symptomatic. Before the procedure, each patient's colon was sprayed with indigo carmine dye, an effective way to highlight any NP-CRNs.
NP-CRNs were identified in 9.35% of all patients (n = 170), with a higher rate of occurrence (15.44%) in the surveillance group. NP-CRNs were 10 times more likely than polypoid lesions to contain cancerous cells "irrespective of tumor size," and depressed lesions presented the greatest cancer risk. American doctors have never been very concerned with NP-CRNs, believing them to be uncommon in the United States, but Soetikno emphasizes that "[NP-CRNs] are important, because they are much more likely [than polyps] to be cancerous."
Doctors who perform colonoscopies may need additional training in identifying NP-CRNs. A 2006 study in the New England Journal of Medicine concluded that some physicians were 10 times more successful than their colleagues at locating precancerous polyps with colonoscopy. Accuracy correlated to time spent conducting the procedure, and doctors may need to take longer than the recommended 6-minute minimum to ensure a thorough examination.
In addition to being hard to see, NP-CRNs are often hard to excise. Dr. David Lieberman, a gastroen-terologist from the Oregon Health & Science University in Portland, Oregon, and author of an editorial accompanying the JAMA study, writes that
"Complete removal of the lesions may be particularly difficult since they have indistinct borders that are hard to identify. Remaining tissue can later turn into cancer, often between screening tests." Further studies are needed to determine the long-term prognosis for patients found to have NP-CRNs.
According to the American Cancer Society, nearly 50,000 Americans die from colorectal cancer each year, making it the second leading cause of cancer death in the United States. Approximately 108,000 new cases are diagnosed annually, with the highest incidence in African American men. Early diagnosis and treatment of colorectal cancer offers a 5-year survivability rate of 90%. Yet despite recommendations that all adults get screened at age 50, almost half fail to do so, possibly because colonoscopy is invasive or embarrassing and requires unpleasant preparation and sedation. For reluctant individuals, virtual colorectal screening is a better alternative than none at all, but Medicare and most private insurance companies do not cover the procedure. That, combined with the results from the JAMA study, may mean patients will just have to take their colonoscopy the old-fashioned way.
Gecko toes inspire new surgical bandages
Nature has long played muse for would-be inventors, inspiring everything from repellant paints (based on lotus plant leaves) to ultrasonography (modeled after animal echolocation). One of the latest examples of biomimicry may have surgeons climbing the walls to get their hands on it: a gecko-inspired, biocompatible, biodegradable bandage.
The material was invented by researchers at the Massachusetts Institute of Technology (MIT). In a study published in February's Proceedings of the National Academy of Sciences, professors Robert Langer and Jeffrey Karp explain how their 21-member team fashioned "biorubber" in accordance with gecko foot mechanics, building on the research of Dr. Kellar Autumn of Lewis & Clark University and his Gecko Team. Autumn's Gecko Team was first to establish what lay behind the gecko's amazingly ?sticky' feet. In a 2002 issue of the Proceedings of the National Academy of Sciences, Autumn explained how geckos adhere to surfaces through an intermolecular process that is "mechanical rather than chemical," identified as van der Waals force. Gecko toes are covered with tiny hairs, called setae, and the Gecko Team determined that the number, shape, and spacing of these setae are what enable geckos to cling?even upside-down?to a variety of surfaces, including wet and smooth ones. Autumn said that the setae from one gecko theoretically generate enough force "to support the weight of two medium-sized people."
Applying this knowledge, Langer and Karp used mi-cropatterning to mold their biorubber, creating rows of infinitesimal pillars spaced just far enough apart to interlock with living tissue. The rubber is then coated with a sugar-based glue that adheres firmly even to moist surfaces. This "internal Band-Aid," as Karp refers to the material, has a variety of potential uses in surgery. It could prove especially valuable in bariatric surgeries, patching up a leaky bypass, for example. In some situations, it could replace staples or sutures, decreasing complications and saving time in the operating room.
The micropatterning technique allows adjustments to the spacing between each pillar, thereby varying the material's elasticity or degradability. Bandages could be customized to suit specific applications. They possibly could be impregnated with time-release drugs, such as antibiotics and antinflammatories, enhancing their usefulness. Karp offers the delivery of heart medications as a practical application for the bandage, explaining that the material's adhesive and elastic properties would allow it to remain affixed to a beating heart without interfering with cardiac function.
The only trials conducted thus far involve animal tissue and live rats, but these have been so successful that Karp believes human applications may be no more than 2 to 5 years away. When the bandages were used on intestinal tissue from pigs, they proved twice as adherent as adhesives lacking the nanobumps. In the rat studies, the glue-coated biorubber proved 100 times more adhesive than uncoated biorubber and triggered only mild inflammation.
Karp and Langer are both faculty members at the Harvard-MIT Division of Health Sciences and Technology. They have secured patents for both the biomaterial and adhesive. Next, they hope to license the technology or start a company to manufacture the bandages and expand on their research. They would also like to find a name for their new material; their first choice, "geckel," was already taken.
Image courtesy of Dr. Kellar Autumn, Associate Professor of Biology at Lewis & Clark College. Autumn K, et al. Evidence for van der Waals adhesion in gecko setae. Proc Natl Acad Sci USA. 2000(99); 12252-12256.
"We've got a bleeder!"
The next time that phrase is uttered in the operating room, you may find yourself reaching for Evicel?, a liquid fibrin sealant. The Food and Drug Administration (FDA) recently expanded approval of Evicel? previously approved for use as an adjunct to hemosta-sis in liver and vascular surgery?to include general surgery applications. Evicel contains fibrinogen and thrombin, two proteins found in human plasma that are essential to fibrin production, which everyone's blood needs to form clots following an injury.
Did you know?
$2.1 trillion—National health spending in 2006. (Health Affairs, 2008)
1.2%—Amount the average worker's earnings dropped in 2007 when adjusted for inflation. (Bureau of Labor Statistics, 2008)
$168 billion—Total cost of the recent "stimulus package" President Bush signed into law in February 2008. (New York Times, 2008)
19%—Percentage of Americans who say they plan to spend their stimulus rebate. (Associated Press-Ipsos Poll, 2008)
Evicel works by sealing small blood vessels that are cut during surgery. The liquid is sprayed or dripped onto the surface of the cut vessels to stem bleeding. According to Dr. Jesse L. Goodman, director of the FDA's Center for Biologics Evaluation and Research, "This approval provides a new option to help control bleeding during general surgery, when other approaches and techniques are ineffective or impractical."
The FDA reports that a trial involving 135 abdominal surgery patients found Evicel to be "safe and effective in controlling bleeding." While some patients experienced adverse effects, such as anemia, abdominal abscess, intestinal blockage, and loss of urinary bladder tone, these effects were generally outweighed by Evicel's benefits.
Evicel is derived from human plasma and contains no aprotinin, which is a protein extracted from bovine lung tissue that has been associated with adverse effects in many patients. The human plasma in Evicel is obtained from donors, who are prescreened for blood-borne pathogens. The fibrinogen and thrombin components undergo additional processes to further reduce any risk of Evicel transmitting bloodborne viruses to patients. As with any human plasma product, however, the risk of disease transmission can never be wholly eliminated.
Ethicon, Inc, which developed Evicel in collaboration with Omrix Biopharmaceuticals, cautions that "Evicel should not be injected directly into the circulatory system or used for the treatment of severe or brisk arterial bleeding." Omrix reports that it is currently working with Ethicon on a fibrin patch that could help control brisk bleeding during surgery.