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DDX cyanosis with normal O2 sats?

Discussion in 'Pediatrics' started by dkwyler94, Apr 29, 2004.

  1. dkwyler94

    dkwyler94 Senior Member
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    I am seeing a patient on my rural health rotation. He is 15 months and came to the clinic with cyanosis of the lips and fingers. His O2 sats were normal. He had a previous occurance and 7-1/2 weeks. He had a normal PE. No murmur reported at birth. CXR normal. Hx of illness two weeks ago.

    I have come up with some hemoglobinopathies, I was wondering if anyone else has any ideas. I am an MSIII and told the doctor I would spend some day researching it, but I don't have my medical texts here with me.

    Thanks
    David
     
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  3. kickazzz2000

    kickazzz2000 Member
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    Sounds like Raynauds' Phenomenon...does it happen when exposed to cold temps?
     
  4. kickazzz2000

    kickazzz2000 Member
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    You said no murmurs at birth, but did you check for yourself?

    Does the kid ever get tired and squat?
     
  5. omores

    omores sleep deprived
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    Cyanosis in the setting of normal O2 sats suggests methemoglobinemia. It'd be interesting to see what this kid's blood looked like (chocolate brown?) and whether it changed color in response to oxygen -- if not, you've got a likely candidate.

    If blood tests do reveal an increased percentage of methemoglobin, you've got to consider whether it's congenital or acquired. A careful history might help you out, including a detailed family history, since congenital cases often run in families (hemoglobin M--autosomal dominant; cytochromeb5/cb5 reductase deficiency--autosomal recessive or compound heterozygous).

    The two acute episodes argue against a congenital form, but you could be dealing with heterozygous cb5 reductase deficiency + acute stressor. You'd want to ask about recent medications, toxin exposures, and the source of drinking water (since nitrates in well water can cause this). There have been case reports of methemoglobinemia in kids who eat crayons: some of them contain aniline dyes, which are a well-known cause of methemoglobinemia. The recent illness is intriguing -- what was it? Sometimes acute methemoglobinemia follows diarrheal illnesses, for reasons that are still debated.

    If the blood does change colour in response to oxygen, you might be thinking of a low-oxygen affinity hemoglobin, or a pulmonary or cardiac cause (which would imply that the O2 sat reading was wrong and the CXR was deceptive). Raynaud's is an interesting suggestion, but you'd expect a clear history of cold exposure, sharply demarcated colour change, and no cyanosis of the lips. There's a similar condition called acrocyanosis -- blue hands and feet caused by vasospasm, sometimes stress-induced, but from what I know it's usually seen in adults, more common in women, and doesn't cause blue lips.
     
  6. Anasazi23

    Anasazi23 Your Digital Ruler
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    I've seen a lot of kids who are actually experiencing seizures accompanied with cyanosis. An eeg might be worthwhile.

    Just a thought.
     
  7. omores

    omores sleep deprived
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    Anasazi -- I'm curious: do you know how the seizures and cyanosis are related?
     
  8. Anasazi23

    Anasazi23 Your Digital Ruler
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    Some children, depending on the seizure type, experience tonic contractions that are associated with breath-holding. This can cause the cyanosis, and the mother often reports "blue lips and fingers" for the duration of the seizure. Of course, if the extremities are not obviously tonic or clonic, it may be much less obvious to pick up.
     
  9. dkwyler94

    dkwyler94 Senior Member
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    Thanks for the thoughts. It is my rural FP rotation and the kid was seeing one of the other doctors in the practice. I took a quick history so I could do some research, but the doctor did the physical. The mother stated she had not ever been told about a murmur and the doctor did not hear one.

    The patient continued acting pretty normal throughout both events per the mother, so I wouldn't expect it was a seizure (abscence) or other kind.

    Methhemoglobinemia was the most likely cause I came up with and suggested to the doctor. She decided at this point to do a heart echo to R/O any cardiac disfunction. I believe she is going to do the blood-filter paper test to look for coloration at the next visit. I didn't come up with this until after the patient had left.

    Thanks for the thoughts. Of course everything goes a bit slower when working up a Pt when they have to drive 200 miles for an echo, but I will post what subsequent findings are.

    Thanks
    David
     
  10. omores

    omores sleep deprived
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    Yes, please do keep us posted!
     
  11. dkwyler94

    dkwyler94 Senior Member
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    As promised, I will give you follow-up on this case as it progresses. I am almost done with this rotation, but will be calling the physician if we aren't finished with the work-up and diagnosis prior to Friday. I am curious as to what it turns out to be.

    The cardiac echo was performed and was negative. I did some research on methhemoglobinemia. There were a few additional blood tests recommended to rule out other potential causes. CBC, electrolytes, the basics. When the doctor gets these blood tests, she will be doing the filter paper test to examine the color change. If it appears prolonged and the other tests are negative, the doctor will send out for a hemoglobin study.

    It sounds like there is a test, performed with basically a pulse ox that uses four light waves instead of two which can indicate the % of hemoglobin bound versus the O2 saturation in the blood. Unfortunatly, in a town of 2000 it is a little hard to come by this.


    David
    PS. I must say, rural practice is quite different then in the city. In some ways more fun if you are a maverik and want to do everything, but it sure would be nice to not have to always be sending everyone out. A work-up really takes a very long time. :sleep:
     

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