Low O2 Sats

Orianna2000 · Jul 9, 2014

My male MC has encountered an alien fog that's caused an allergic reaction, seriously blistering his lungs. He's coughing, wheezing, hacking up blood, etc. The doctor checks his O2 sats, and it's a dangerously low number. Not low enough to kill him or cause permanent brain damage, but low enough that she wants to evacuate him immediately, despite the risks involved (such as the alien fog that's still lurking outside). She puts him on oxygen and they head off to the hospital, where he stays for at least a week before recovering.

My question is, what's a good number to use for his O2 sats? I tried doing research on how low it could go without killing you or causing brain damage, but the Google results I found were confusing. I arbitrarily chose 75 as the magic number, but I honestly have no idea if it's too low to be realistic.

Any doctors or nurses out there able to help?

cmhbob · Jul 9, 2014

75 is going to have him cyanotic (blue lips, fingernails, etc.) Certainly he'll be on O2. I was on 2 liters of oxygen with sats of 85-88, and no cyanosis.

Los Pollos Hermanos · Jul 9, 2014

I found these - don't know if you've seen something similar, but they've got some decent info:

http://www.patient.co.uk/doctor/pulse-oximetry

http://www.anesthesiaweb.org/hypoxia.php

midazolam · Jul 9, 2014

Worrisome is below 90. Very worrisome is below 80. This is just how I approach it, and there's no hard and fast rule - a "dangerous" O2 sat will depend on a lot of factors (I've seen some very sick patients live on the vent with an O2 sat in the 60's, but not for long).

I think 75 is a good number for the situation you described.

Orianna2000 · Jul 9, 2014

Thanks, guys! This is very helpful information.

nikkidj · Jul 9, 2014

Agree with midazolam, on all counts.

Chekurtab · Jul 10, 2014

If you MC is human, you need to describe a human type of allergic reaction. Terms like 'blistering lungs' are not appropriate, especially coming from a doctor. The O2 saturation is just one of the abnormal vital signs and has to correlate with the rest of the vitals, depending on the type and severity of the reaction.
Hope it helps.

Orianna2000 · Jul 10, 2014

Actually, they're not sure whether it's an allergic reaction, or burns caused by the fog's acidity, or something else entirely. Exposure to the fog causes disorientation from breathing it in, along with fluid-filled blisters on any exposed skin or tissue. The lungs are damaged and can't get enough oxygen, so the victim dies, unless they receive immediate medical treatment. While they're dying, the fog extracts their red blood cells to feed on.

Also, it eats through rubber and other substances, such as hazmat suits, disintegrating them in a matter of minutes.

Aleiarity · Jul 31, 2014

My daughter needs to be at 85 or above; otherwise, we have to put her on oxygen.

If she dips below for short periods like crying when she's really mad, it's not a huge deal. She gets monitored pretty closely if she's below 80, but that hasn't happened in awhile.

How would they know his lungs were blistering? How would the fog extract the red blood cells? Wouldn't the blisters (presumably filled with lymphatic fluid) get in the way?

Orianna2000 · Jul 31, 2014

I suppose at this point they don't know for sure his lungs are blistering, but it's a good bet, since he's been breathing the fog for several minutes and all of his exposed skin is blistered.

There should be enough exposed skin between the blisters for the fog to creep in and steal erythrocytes. It's a mist, so it doesn't need a large amount of skin to be able to feed. The skin would be inflamed, but don't red blood cells rush to the site of inflammation? (I could be wrong.)

MDSchafer · Jul 31, 2014

Chekurtab said:
If you MC is human, you need to describe a human type of allergic reaction. Terms like 'blistering lungs' are not appropriate, especially coming from a doctor. The O2 saturation is just one of the abnormal vital signs and has to correlate with the rest of the vitals, depending on the type and severity of the reaction.
Hope it helps.

Yeah, this.

In the field all you're really going to have access to is a pulse ox and a stethoscope, my mom and I carry both in our cars so it's not uncommon for medical professionals to have that stuff available. If there's blisters forming in the lungs what you're going to see is difficulty breathing and a low Po2.

I've not really heard of fluid filled sac blisters forming on the lungs, but I suppose it's possible. Such a condition would put someone at risk for a pneumothorax, so it's a very dangerous thing, but without an X-ray or some sort of imaging I don't know how you could figure that out in the field.

What I see a lot of people get wrong about medicine is the thought that we can diagnose things super quickly. When you're in the field it's treat first, diagnose later. In this case you would put on oxygen, maybe even intubate (I know a doc who carries a full kit and an ambu bag in his backpack.) in order to keep a clear airway because if you hear hoofs you think horses not zebras.

Orianna2000 · Jul 31, 2014

It's happened before, that's how they know what's happening in the field. The same character was exposed to the fog during an exploratory mission--it ate through his hazmat suit and he breathed the fog for a couple of minutes before anyone realized the problem. He was taken back to their base, where they have a fully-equipped infirmary, and the doctor figured out that his lungs were affected and put him on oxygen. It wasn't too serious; he healed after a couple of days.

This time, he's exposed for much longer, so the blisters would be much more severe. The doc sees the same symptoms as before, just much worse. He's struggling to breathe and coughing up blood. She treats him as best she can under emergency circumstances, giving him oxygen when his O2 sats drop, and insisting on evacuating to the nearest hospital the moment the fog is neutralized.

Am I wrong to have the doctor see the same symptoms, from the same cause, and assume the same diagnosis? She's proven right once they get to the hospital.

MDSchafer · Jul 31, 2014

Orianna2000 said:
Am I wrong to have the doctor see the same symptoms, from the same cause, and assume the same diagnosis? She's proven right once they get to the hospital.

It depends on the doc. There's nothing wrong with slapping oxygen on someone and transporting them to a hospital. But how much blood are we talking about here? Is the guy coughing up bloody mucous, or coughing up blood like a vampire after feeding? And where is the blood coming from?

Also, odds are, if something is caustic enough to cause lung blisters there'll also be inflammation of the trachea and oral cavity.

Orianna2000 · Jul 31, 2014

I hadn't considered blisters in his mouth or trachea. That's slightly more problematic, since he needs to talk on his way out--I don't want him intubated, which the doc would certainly do if his airway was swelling closed. I'll have to give this some thought.

The blood is just a splattering, nothing too serious. Well, I suppose any amount of blood in the lungs is serious, but it's just a spray of bloody mucous. Nothing approaching vampiric levels!

WhitePawn · Aug 2, 2014

Agree w Midaz on the value.

What he wears to deliver the oxygen will vary by the amount needed, for whatever that's worth. The little nose prongs are for low doses of O2. Basic mask, mid-range. The mask with the bag hanging off it (a non-rebreather) will be for the highest dosage. If the issue isn't solved by that, then he will be intubated. Ventilator time.

If the fog "burns", maybe you want to check out burn injuries. I don't have first hand knowledge of those apart from a brief ED viewing on occasion. Usually with things like bbq or campfire incidents. A brilliant fellow sprays the fluid or whatever into open flame and gets a lungfull of the resulting fiery eruption. He'll breathe in, in "oh-shit-fire" surprise, and get a first-hand taste of flame all the way down to his lungs. What I can tell you is that the whimpering and mewling never stops. Forty year old men curl into fetal positions crying and kick the mothering instincts of those around him into overdrive. Some survive, some don't, depends on the tissue damage...but I don't know how the lung itself is treated...they all get shipped off to the burn unit.

On another note, O2 is a hot, dry, burning drug. It isn't comfortable and can damage in high doses over the long-term. Catch-22 tradeoff sometimes, but, aim for breathing now and worry about the rest later is how most approach it.

Orianna2000 · Aug 2, 2014

Thanks again for the help!

They're in a fallout shelter without access to their infirmary, so all they have is a standard cannula for the oxygen. No masks, although that's probably what he needs. But they do take him to the hospital pretty quickly, so he'll survive.

They never do figure out whether the blisters are burns of a sort, or an allergic reaction, or something else. Maybe someone at R&D figures it out, but those in the field aren't notified, since they're already moving on to the next crisis.

Low O2 Sats

Orianna2000

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cmhbob

Did...did I do that?

Los Pollos Hermanos

Craving the next chocolate hit...

midazolam

Orianna2000

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nikkidj

Chekurtab

Smart donkey. Please don't call me-

Orianna2000

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Aleiarity

mostly harmless

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MDSchafer

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MDSchafer

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WhitePawn

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