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Clinical Update: Cataract
TASS Outbreak: Lessons Learned
By Marianne Doran, Contributing Writer
 
 

The specific cause of last year’s outbreak of toxic anterior segment syndrome (TASS) continues to elude experts. But in digging for answers, the researchers uncovered areas of vulnerability in some of the nation’s cataract surgery centers and hospitals.

Unlike the earlier TASS outbreak in 2005, which was traced to endotoxin contamination of the balanced salt solution manufactured by Cytosol Laboratories, the recent flood of TASS cases could not be directly linked to any ophthalmic product. That’s good news, but it also means that preventing future outbreaks won’t be as simple as switching to another product.

TASS experts investigating the recent outbreak believe improper instrument cleaning and sterilization procedures were associated with the outbreak in many instances. Correcting these problems will require the establishment or improvement of instrument-processing protocols, more extensive staff training and closer oversight of how surgical instruments are maintained.

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Calling Dr. Mamalis

Nick Mamalis, MD, professor of ophthalmology at the University of Utah, has been the primary point of contact for surgeons dealing with suspected cases of TASS. Eighteen years ago, he and his colleagues set up the Intermountain Ocular Research Center, which is dedicated to evaluating unexplained inflammation after ocular surgery. They ultimately coined the term TASS to describe the acute, noninfectious inflammation that can occur after anterior segment surgery.

Since that time, Dr. Mamalis has fielded countless TASS-related calls and e-mails from concerned surgeons around the country. Normally, he receives one or two such e-mails a week. But in February 2006, the number of inquiries jumped significantly, reaching more than 100 established cases by May 2006.

“We saw a marked increase in the number of centers and surgeons who were reporting TASS,” Dr. Mamalis said. “In fact, it got to the point where we were almost overwhelmed. We didn’t have the resources available to analyze these, so we set up the TASS Task Force.”

Taking TASS to task. This Task Force, which also included public health experts and industry representatives, sent detailed questionnaires to the reporting centers. Answers to the questionnaires suggested several potentially problematic products. These included intracameral anesthetics and antibiotics; preservatives and stabilizing agents in epinephrine added to balanced salt solutions; reusable cannulas with residual cortex or viscoelastic; and reusable IOL inserters.

But further investigation did not identify a specific product that could explain the outbreak, according to Task Force member Arjun Srinivasan, MD, a medical epidemiologist at the Centers for Disease Control and Prevention (CDC). “We did test products for endotoxin, including additional balanced salt solutions and viscoelastics that some people were concerned about,” he added. “But we did not find unacceptably high levels of endotoxin in any of the products we tested. No specific product or type of product seemed to be linked to a large number of cases disproportionate to its share of the market —and that was one of the things we were looking for.

“That’s not to say, of course, that a product didn’t cause the problem,” Dr. Srinivasan continued. “It’s just that if a product was involved, we were unable to identify it based on the information we were able to collect.”

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Remember Sterile Procedure?

What did become clear during the investigation is that, in some centers, oversight of the cleaning of instrumentation is not as stringent as it should be.

Lack of uniformity. “We found that many places had no set protocols for the cleaning and sterilization of instruments or certainly no ophthalmic-specific protocols,” Dr. Mamalis said. Surgeons often have little involvement in these procedures. “Until a specific problem comes up that forces them to sit down with the staff and look at the methods that are being used, surgeons are often unaware of what’s going on with the surgical instruments,” Dr. Mamalis said.

Task Force member Henry F. Edelhauser, PhD, a professor of ophthalmology and director of ophthalmic research at Emory University, added that staff members often don’t follow the “directions for use” that come with the instruments. “These little pieces of paper get put away, and sometimes with the changing of personnel and the speed of surgery, things get overlooked,” he said.

Sterile, maybe, but not exactly clean. Dr. Edelhauser pointed out that the viscoelastics used in cataract surgery are a potential source of trouble if they aren’t properly removed from the surgical instruments. “If the viscoelastics dry on the instruments—the inserters, the reusable cannulas—and then the instruments go into an ultrasonic bath or enzymes, it’s hard to dislodge them,” he said. “The viscoelastic can absorb detergents, and when the anterior chamber is reformed, those detergents are left in the eye.”

Cleaning should not be rushed. Time between surgeries is another related issue. The Task Force noted that the number of cataract surgeries performed in the reporting centers on an average day ranged from five to 50, with a median of 15. (The median number of instrument trays in use was three.) The short duration between cases leaves little time to reprocess and properly clean the surgical instruments. “A surgeon can do a phacoemulsification in four to six minutes, but it may take up to 20 to 25 minutes to clean and sterilize the surgical tray,” Dr. Edelhauser noted. “So the answer is, either allow more time between surgeries or have more surgical trays.”

There’s nothing like a fresh bath. The Task Force identified several other instrument-processing issues that may lead to TASS. These included inadequate or delayed flushing of reusable irrigation/aspiration hand pieces and tips and inadequate cleaning of ultrasound baths used to reprocess surgical instruments. Water baths can become contaminated with gram-negative bacteria, potentially producing heat-stable endotoxins that will survive autoclaving. Ideally, ultrasound baths should be emptied and cleaned after each use, and certainly at the end of each day. Autoclave units also should be cleaned thoroughly and regularly and undergo routine maintenance to prevent endotoxin contamination.

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Guidelines to the Rescue

Dr. Edelhauser put together a meeting at Emory last September to establish guidelines for the cleaning, sterilization and processing of ophthalmic instruments. In addition to Task Force members, the attendees included representatives from related nursing groups, industry, the CDC and the FDA. The guidelines are now in final draft form and are awaiting approval from the agencies and individuals involved. Once approved, these guidelines will be sent to surgery centers reporting TASS so that the surgeons and staff can begin to identify and address any problems they might have.

“It will be very helpful to get these guidelines out because hopefully they will at least give surgical centers and hospitals something they can use to help eliminate the processing of surgical instruments as a cause of TASS,” Dr. Mamalis said. “If we could do that, we would go a long way toward decreasing the incidence of TASS overall.”

Take a fearless inventory. Although the specific cause of the last TASS outbreak remains somewhat of a mystery, the experience provides valuable lessons for all cataract surgeons. “If there was one thing I would recommend to surgeons,” Dr. Mamalis said, “it would be to spend some time looking at exactly how the instruments are being processed at your facility and make sure that adequate protocols are in place for these instruments.”

He also pointed out the need for people involved in a TASS outbreak to look beyond their first impressions and assumptions. “When these outbreaks occur, it’s important that all potential factors are looked into because often the surgeon’s first thought of what caused the outbreak doesn’t turn out to be the case.”

Share your experience. Surgeons who suspect TASS should contact Dr. Mamalis at nick.mamalis@hsc.utah.edu and fill out the TASS questionnaire. The CDC is another good source of assistance if TASS is suspected. “CDC is always available, willing and very interested in helping any center that is having a cluster of TASS,” Dr. Srinivasan said. “We work together with state and local health departments to help investigate TASS clusters. Much of it can be done over the phone, but, if necessary, we can work with health departments to get people on site to do an investigation.”

Increased awareness of TASS, timely reporting of suspected cases and the continuing input of ophthalmic surgeons from around the country will provide the best defense against this potentially sight-threatening condition.

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Is It TASS?

Toxic anterior segment syndrome is more common than most surgeons realize. In one survey, more than half of those responding had seen at least one case in their practice. Here are some of the signs and symptoms that suggest TASS:

  • Rapid onset, typically developing within the 12 to 24 hours after surgery
  • Blurry vision, eye irritation
  • Marked anterior segment inflammation
  • Diffuse limbus-to-limbus corneal edema
  • Hypopyon
  • Possible fibrin formation
  • Pupil often is dilated and less responsive to light
  • Elevated intraocular pressure developing a few days after surgery

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