Tuesday, May 15, 2018

Confusion, Diaphoresis, and Hyperventilation Aboard a Private Airplane

This was intended to be a case report but the amount of work required to publish a case report is just too great to justify it.  The publishing landscape has been flooded with an attendant raft of predatory journals, so one must be very careful.

This will be an online interactive case report.  I will tweet this post, asking for comments and diagnoses in the comments below (preferable to twitter comments) and update with the answer and a discussion in 1-2 weeks.

A 68 year-old otherwise healthy male passenger was flying with his friend, a pilot, in a private plane from California to Montana for a fishing trip.  Within an hour after takeoff, he became confused and diaphoretic and was hyperventilating, then he lost consciousness for approximately 20 minutes.  The pilot applied supplemental oxygen and checked his passenger's arterial oxygenation via oximetry, finding it to be 95%.  The flight was diverted for a medical emergency.  During descent and landing, the passenger regained consciousness but remained confused.  In the emergency department of a nearby hospital, he had normal vital signs, and had a non-focal neurological examination, but remained confused.  Representative images from CTA of the chest are shown below (click on the images to expand).  A head CT was normal excepting for some age related atrophy.  What is the diagnosis?

12 comments:

  1. pneumomediastinum from a pneumothorax?

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    1. No pneumomediastinum or PTX, but that's a good thought

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  2. I see thrombosis In the right lung. HL

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    1. That is correct. But it is not the final diagnosis. Crosskerry warns of “search satisfycing” and its germane here

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    2. I see a ton of "search satisfying" in hospital medicine. Based on the cross sections of the CT I have, I'm not entirely convinced there's anything wrong with him that explains his presenting complaint. Based on your response to the answers, I feel like the admitting diagnosis from the ED physician was PE and there was no further explanation given, and investigation was otherwise unrevealing. You're not telling us something.

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    3. Now I see your portal venous air. Decompression sickness makes sense. I'm sure that's not how it was presented to you though.

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  3. Confusion from a pulmonary embolism with a normal O2 sat is not a common pattern. Fluctuating confusion from a dissection would seem more likely. I have crap CT chest skills but doesn't the aorta look abnormal in the second image?

    By the way, isn't "search satisfycing" exactly what we do every day in medicine? We get enough evidence to make a treatment decision and then stop investigating further. Better to refer to premature satisfycing instead. Anyway, I'm going to a lecture by Croskerry on Friday.

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    1. Tell Pat the Phlegmfighter says hi. But don't tell him that I said he made "search satisfycing" up. It's a valid conceptual idea, but it has no empirical backing. I think it is often used in relation to trauma surveys.

      In this case, I think the failure is, after getting a "finding" of PE, to call that the "diagnosis." But that ditzle PE is totally insufficient to explain his symptoms.

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  4. decompression illness, flying after diving, +/- air embolism?

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  5. Evangelos PapadomichelakisMay 16, 2018 at 7:06 AM

    Altitude-induced decompression sickness.

    Air bubbles in portal circulation and IVC.

    Well described in aviation

    https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/DCS.pdf

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    1. correct! Most folks don't know or don't bother to ask what type of aircraft it is. Unpressurized aircraft are authorized by FAA to cruise at up to 25,000 feet, and beyond 18,000 feet there is a risk of decompression and its associated symptoms.

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    2. Evangelos PapadomichelakisMay 16, 2018 at 11:52 AM

      Thanks for the puzzle, Scott!

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