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CT Scans May Cause Medical Device Malfunctions

2008-07-18 08:07:35
By: Richard Hellman, MD, FACP, FACE

On July 15 , 2008, the FDA released a report stating that direct x-ray exposure from CT scanning has been reported to not only cause malfunction of cardiac pacemakers and defibrillators, but also to affect other devices, including neurostimulators and implanted or externally worn drug infusion pumps, including insulin pumps.

The FDA reported that the higher dose-rate capability of the newer x-ray machines, their increased use, and better reporting systems may all contribute to the findings. But it is far from clear as to how often insulin pumps, including both hospital infusion systems and the patient’s own external insulin pump, malfunction during CT scans.

In the case of pacemakers and implantable defibrillators, the most common effect of the prolonged exposure to the higher x-ray dose, often found with the newer CT scanners, including spiral CT's, is a over-sensing of the device. This can cause serious problems, including discharge of the defibrillator and pacemaker pauses. The neurostimulators have also been associated with unintended shocks. Although the report did not detail the effect on the insulin pumps, it is likely that the particular engineering of the pump and the dose of radiation may interact in a variety of ways, none that are desirable.

In the short term, we will monitor this carefully, but suggest that all clinicians be aware that, if possible, it may be best to have the insulin pump off during the CT scan. In any case, the insulin pump should be checked afterwards for malfunctioning if it is near the CT scanning device during the scan.

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Shashank R Joshi – India

August 27, 2008 - 14:51

Subject: Byetta and Pancreatitis-Practical Issues

Byetta and Pancreatitis - An Indian View
-- Dr. Shashank R Joshi, MD, DM, FACE, FRCP(Glg)
Endocrinologist, Mumbai India
Hon Editor, Journal of The Association of Physicians of India
Chair, Indian Chapter of AACE

Both your bezoar case and pancreatopathy make good reading. Incidentally, I reviewed global literature of all agents of diabetes and their impact on the pancreas. All secretagogues, as well as glinides, have case reports of pancreatitis reported. However, cause-effect relationship has never been proven, both in animal studies as well as reported anecdotes. In fact, the global reportage of pancreatitis is so small statistically that most cases had some other etiology for pancreatic injury. So currently we do not have sufficient evidence for pancreatic injury due to exenatide, but it stands to reason that in a predisposed individual it may act as a potential trigger for pancreatic injury.

The real worry will be the ongoing LAR preparation which is now under phase 3 trial program

Exenatide has some evidence to suggest that it may trigger a cholinergic response in alcoholics and that could be a beeptive pathway for pancreatic injury

So clinically, exenatide needs the following caveats prior to its use:
1) Chronic alcoholics or abuse
2) Refractory GERD
3) History of acute or chronic pancreatitis
4) Gall stones
5) Gastroparesis

One should avoid or exercise caution to use it in the above stated indications. Our institution avoids byetta in the above mentioned indications till further data will emerge

In India to date, one case of pancreatitis is reported.

Richard Hellman MD – NKC,

August 26, 2008 - 11:06

Subject: Byetta and stomach pain

Dear J.A. Moore,

Your question about Byetta and your nightly pain, which your doctor says is from your stomach, is a very important one, and thank you for asking it. It is not clear as to whether you are free of abdominal pain at this time. If you are pain free at this time, it may be difficult to be sure as to why you had pain in the past. If you are still having nightly pain, then my comments may be more relevant. Since I am not your doctor, I do not know enough about you to make a diagnosis or offer therapy, but I hope I can be helpful in some general suggestions. As we get older, the risk that a pain in the abdomen is a serious medical condition increases. But resistant pain in the abdomen can be from many causes: infections, such as a H.Pylori infection of the stomach, inflammation, such as pancreatitis, or a disease of the intestine called Crohn's disease, motility problems, such as gastroparesis, and other possibilities, vascular problems such as abdominal aneurysms, and also tumors, such as cancers of the stomach and of the pancreas. But there are other, much more common and simple problems, such as irritability of the gastrointestinal tract either due to drugs, such as metformin, or conditions as irritable bowel syndrome. I certainly could not tell from what you have said whether your problem is any of the above, or whether it is or was related to byetta.

But I think your questions are right-on and you should find out why you have had pain and whether it has anything to do with either byetta or to metformin. Your doctor should be able to do some screening tests for pancreatitis, and gastroenterologists can answer other of your questions, but I would encourage you to proceed to ask your health providers to answer your excellent questions.

You should also note that in the editorial I wrote on byetta, I discussed the responsibility of doctors to answer questions of this type. Thank you again for your excellent question. I hope I have been helpful.

J.A. MOORE – Washington DC

August 25, 2008 - 13:47

Subject: Byette

I have been taking Byette and have a nightly pain which the Dr says is my stomach. I am overweight and have high triglycerides. The Drs ran all kinds of tests on my gall bladder xrays plus other tests....including nuclear meds test. Gall bladder tests turned up negative. Then the Gastro Drs said it must be the valve on the stomach that's weak on diabetics and they gave me some medicine that kept me going to the toliet. I quit the medicine after almost a week of torture. But I took 3-Omega Oils capsules 3 times a day and Liptor and Tricore. My lipids were tested two weeks ago and the pain is gone and my Lipids very low in normal range with one type being under the allowable rate but my Endo Dr said that was OK. SHOULD I WORRY THAT I may have or had pancreatitis? I am still taking the Byette plus Metformin and Lantus..