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Up close with gastric aspiration and chest X-rays
A new video that takes a broad look at pediatric tuberculosis started its life as a short film with appeal to what can only be described
as a very, very limited audience. "Pediatric Tuberculosis: A Video Guide to Diagnosis and Treatment" (now available from the Francis J. Curry National Tuberculosis Center in San Francisco) was originally conceived as a short film about how to collect gastric aspirate from young patients.
The video’s featured physician — Ann Loeffler, MD, the one-woman pediatric faculty
at the Curry center — has a special talent for that particular task, she cheerfully confesses. "One day," she recalls, "someone said, Ann, you do a very good gastric aspirate. Why don’t we make a video of you showing how?’"
For a time, that was the plan. Then Loeffler says she found herself reconsidering. "You know, guys, that’s really a niche market," she remembers saying. At that point, the concept expanded to a project that would cover not just gastric aspirates, but all the basics of handling pediatric TB. It’s probably a good thing, since passing a tube down the throat of an unwilling six-month-old is just one of several challenges pediatric TB specialists must be ready to surmount.
For example, the video spends lots of time addressing pediatric diagnostics, with Loeffler taking viewers through the various pitfalls of reading youngsters’ chest radiographs. "They don’t always look the way specialists in adult radiography expect them to," she notes. Often, for example, the disease isn’t cavitary, and often not in an apical location, but rather in any lobe. (Indeed, it’s multi-lobar 25% of the time, Loeffler notes.) "Frequently, it’s associated with hilar lymph node enlargement, which some adult radiologists misinterpret as pulmonary vessels," she adds.
As age rises, gastric yield falls
As for collecting those gastric aspirates, Loeffler says the first thing to know is that as a diagnostic tool, "they’re very imperfect." Overall, the yield is about 40%, she says, for the simple reason that children have very few organisms.
The younger the child, the better the yield, she notes. "In children under six months, the yield is almost 100%," she adds. For that reason and others, Loeffler hardly ever does aspirates on children older than two or three years. "Can you imagine strapping down a four-year-old, especially when you know the yield will be only about 30%? That child would never speak to you again, much less take the medications you prescribe!"
For situations when an aspirate is indicated, Loeffler says the best yields can be found in early-morning, first-day collections (following a night when the child is NPO). The reason why that’s the case may have something to do with fear, she speculates. "My theory is that by the second day, they see me coming, and they have that fight-or-flight response, and it empties their stomachs," she says.
On the subject of drugs, Loeffler says it’s time to put to rest any reservations about kids and ethambutol. "Two recent papers on this subject conclude there’s maybe been one case in the world where using ethambutol has resulted in optic toxicity," she says. Even so, guidelines from the Centers for Disease Control and Prevention continue to counsel physicians to "weigh risks and benefits" before giving the drug to children who aren’t old enough to report changes in vision.
Another argument for four drugs is the fact that obtaining a specimen from a child is difficult, with the result that data on resistance are hard to come by, "so you’re essentially working in the dark with a lot of kids," Loeffler points out. Besides, the guidelines also say four drugs should be used whenever the county of residence has more than 4% background resistance rate, or when the source case acquired the disease in such an area.
Avoiding a messy situation with resistance’
"I get a lot of calls from people who started with three drugs and got into trouble," she says. "That means adding two more drugs — drugs that have a lot more toxicity, cost a lot more, and sometimes have to be given more than just once a day." True, children typically have small bacillary loads and manage to muster their way to a cure, even with suboptimal regimens, she concedes. "But you really don’t want to get into a messy situation with resistance," she concludes. "So why go there?" All the same, she warns parents to watch their children closely for any signs of optic toxicity, such as rubbing of the eyes, sitting closer to the TV set, or a diminished ability to manipulate small objects.
The video is the successor to an earlier audio tape Loeffler made, focusing mostly on the how-to’s of treating latent infection in children. That tape comes with free CME credits and is still available at no cost. The new video comes with
a 27-page booklet filled with what Loeffler calls "meaty, practical information," including dosing charts for once- and twice-weekly schedules suitable for hanging in a clinical workspace. CME credits accompany the video. The video, booklet, and CME credits are free of charge.
To obtain a copy of the video and booklet or of the audio tape, contact the Curry TB Center at (415) 502-4600 or via e-mail at firstname.lastname@example.org.