Chapter 130
Well, for now, the two paradoxical findings are just too clear.
First, the lactate level is 4.5.
That's evidence of metabolic acidosis.
But the pH is 7.45.
That's alkalosis.
And the partial pressure of carbon dioxide is 10.
Normally, when septic shock hits and lactate builds up, the body shifts acidic.
Then the lungs compensate by blowing off CO2 and trying to bring the pH back to normal.
That's why in the early stages of sepsis, the pH actually rises as compensation.
But it's impossible to drive the pCO2 down to 10.
The human lungs aren't some air compressor.
It means something's mixed in that's forcing the respiratory center itself to make the patient hyperventilate, not just compensating.
In other words, it's not sepsis.
At the very least, it's definitely not ordinary sepsis.
Then what's the cause?
What on earth is the one puzzle piece that can explain the high fever, altered consciousness, hyperventilation, and these bizarre ABGA results all at once?
I had ruled out a few diseases earlier.
Diabetic ketoacidosis?
The blood sugar check came back at 110.
Rejected.
Thyroid storm?
I palpated her neck, and it was normal.
Rejected.
Pulmonary embolism?
Her oxygen saturation is holding steady at 99%.
And the D-dimer didn't light up.
Then what's left is...
'...drugs?'
It's drugs.
A fragment of an old memory buried somewhere in my brain cells flashed to life.
Something I'd only glanced at a few months ago.
No, come to think of it, that's kind of funny.
Why do I keep remembering information from forum posts instead of textbooks?
Is that better for long-term memory or something?
I don't remember the details exactly, but...
'Mm....'
I frowned and rummaged through the archive of my memory.
[Nephrology Ghost: Back in the ER, I almost killed a patient by dumping antibiotics in because I thought it was sepsis, but I ended up saving them by putting them on dialysis. What that means is....]
Ah, it's blurry.
The memory's blurry.
What exactly did they say back then?
They said it looks just like sepsis, so it's perfect for a misdiagnosis.
'Damn. This is why my memory sucks.'
I only remember it vaguely.
This stupid brain of mine saved only the peripheral details and tossed out the key keywords.
I can't remember at all what drug it was.
But I had a hunch.
It's not Infectious Disease territory.
It's Toxicology territory.
One thing was certain: it wasn't sepsis.
It needs an antidote or dialysis, not antibiotics.
I lifted my head with eyes full of confidence.
Baek Eun-seo, standing beside me, also seemed to have reached some conclusion and was about to speak.
Our mouths opened at the same time.
This disease is...
“It's drug intoxication.”
“It's meningitis!”
Two different diagnoses collided head-on in midair.
“Huh? What?”
Baek Eun-seo stared at me with her eyes wide open.
“Huh?”
I looked back at Baek Eun-seo, equally flustered.
Different answers burst out at the same time.
A second-year and a first-year shouting completely wrong diagnoses at each other in the middle of the ER—what a sight.
“Huh? Drugs?”
Baek Eun-seo asked back in disbelief.
“The brain?”
I asked back with an incredulous expression of my own.
“The patient had a 39.2-degree fever and a mental status change.”
Baek Eun-seo began laying out her reasoning, enunciating each word clearly.
“Right. That's why we initially suspected sepsis.”
“Yes. But the ABGA is strange. If it were sepsis, it should be acidic because of the lactate, but the pH is 7.45, so it looks alkalotic. That means respiratory alkalosis is overpowering the metabolic acidosis.”
Oh, not bad.
To think a first-year would analyze blood gases and even use the word 'overpowering.'
“So?”
“I think the intracranial pressure is rising because of meningitis or encephalitis, or the inflammation is directly stimulating the brain's respiratory center and causing central hyperventilation.”
Baek Eun-seo's eyes sparkled with conviction.
“The high fever would be from encephalitis, and the altered consciousness from increased intracranial pressure. The panting makes sense too. So instead of the sepsis bundle, I think we should do a lumbar puncture and use high-dose acyclovir or a third-generation cephalosporin!”
Logical.
A very good approach.
If a young woman has high fever, altered consciousness, and unexplained hyperventilation, suspecting a central nervous system infection is textbook medicine.
But.
Would a meningitis patient breathe that hard?
Usually, when intracranial pressure rises, doesn't breathing become irregular or slow?
As Baek Eun-seo launched into her passionate argument, I quietly turned my head away from her gaze.
Then I hurriedly opened a blue window in midair.
'Come out, you ghosts.'
[Dead Doctors Gallery]
====================
(Lab results included) Looks like DI, but I can't remember exactly what it was.
Author : HellJoseonSlave1
24F. High fever / altered consciousness / hyperventilation. pH 7.45, pCO2 10, HCO3 12, Lactate 4.5. I think it's drugs, but I can't remember.
====================
Posted.
In the meantime, Baek Eun-seo kept trying to persuade me.
“Really? Because of encephalitis?”
To stall for time, I pretended to listen seriously.
“Yes! The intracranial pressure went up and caused central hyperventilation! That's the conclusion I came to, sir. What do you think?”
Baek Eun-seo was 200% certain her diagnosis was correct.
Her reasoning seemed airtight.
If I were a dimwit, I might have nodded along.
“You know, Eun-seo. The thing is...”
I hesitated.
Just then.
[A comment has been posted]
I checked the blue window out of the corner of my eye.
The first comment.
DialTheDialyzer : Yeah. Aspirin. Salicylate.
Short and punchy. The correct answer.
Salicylate.
Aspirin.
DialTheDialyzer : It stimulates the respiratory center and causes hyperventilation, while also causing metabolic acidosis. The two together make the pH look normal. Classic salicylate poisoning
Exactly.
Whatever the reason, this patient has overdosed on antipyretic analgesics and is suffering paradoxical fever and hyperventilation as a side effect.
I raised my head and looked at Baek Eun-seo.
It was time to deliver the unfortunate news to that clever first-year who was feeling so proud of her diagnosis.
“Eun-seo.”
“Yes! Should I put in the orders?”
I shook my head and said in a confident voice,
“It's not a brain problem.”
“What?”
“This is definitely drug intoxication.”
“Doctor, but I think my reasoning is rational...”
Baek Eun-seo still didn't seem ready to give it up.
Well, if she was going that far with her deduction, meningitis or encephalitis would definitely seem like the more plausible scenario.
High fever.
Altered mental status.
Hyperventilation.
They are classic symptoms of a central nervous system infection.
I cut Baek Eun-seo off.
“It is rational. You do have a point. Let me explain why I think it's not that first, and if you're still confused after hearing me out, go run to Chief Park Woong, the attending today, and make your case to him.”
“Ah... yes, sir. I'll listen.”
Baek Eun-seo immediately backed down at the word 'chief.'
I tapped the ABGA results with my finger.
“Eun-seo. Because of encephalitis, breathing hard from increased intracranial pressure is possible. That's called hyperventilation due to central nervous system abnormalities. But here's the thing.”
I looked straight into Baek Eun-seo's eyes.
“Can pCO2 drop all the way to 10?”
“Uh, well...”
Baek Eun-seo fell silent.
“No matter how hard a person pants, it's nearly impossible to get pCO2 down to 10 with spontaneous breathing. Even hyperventilation syndrome patients usually don't go below 20.”
I pointed at the patient's neck.
“Did you feel the neck?”
“Oh.”
Baek Eun-seo's face turned red.
If it were meningitis, there should be nuchal rigidity, a meningeal irritation sign.
“I'll check it properly right now!”
Baek Eun-seo hurried to the patient's bedside, lifted the neck, and tried turning it left and right.
The patient was delirious, but the neck moved very smoothly.
There wasn't a hint of stiffness.
“...Ah.”
Baek Eun-seo let out a sigh.
“It's supple, right? No nuchal rigidity, right? Then the odds of meningitis drop dramatically. If there's high fever and altered consciousness but the neck is soft, you should look for a metabolic or toxic cause rather than an infection.”
Baek Eun-seo hung her head, deflated.
But then she immediately lifted her head and asked with her usual studious, eager gaze,
“Th-then what kind of poisoning is it? An overdose of antipyretics?”
“Aspirin.”
I answered briefly.
“It directly hits the brain's respiratory center and induces hyperventilation, while also wrecking intracellular metabolism so lactate and ketones build up. That's why you get a bizarre ABGA like this patient's, where the pH is normal but CO2 and HCO3 are at rock bottom. And that's why the fever is happening too.”
“Ah...!”
Baek Eun-seo opened her mouth as if she had just had an epiphany.
“Call nephrology on call right away. Tell them we have a patient suspected of salicylate poisoning, the numbers and vitals are unstable, and emergency dialysis may be needed. Also check whether there's an ICU bed and a dialysis machine available.”
“Yes! Understood!”
Baek Eun-seo ran off to the phone.
I immediately sat down in front of the shared computer in Zone A.
Now that we knew the cause, it was time to detoxify.
Salicylic acid is an acidic substance.
We need to alkalinize the urine and help it get excreted.
“Bring me some sugar water...”
I muttered as I entered the orders.
Salicylate poisoning lowers glucose levels in the brain, so glucose has to be given even if the blood sugar is normal.
Clack, clack.
“In 1 liter of 5DW... add Bibon
(* sodium bicarbonate)
and mix it in. Since alkalinization can cause hypokalemia, KCl
(* potassium chloride)
also mix in 20 mEq......”
A perfect combination.
The so-called urine-alkalinization IV fluid.
I just named it myself.
If we give this, the patient's urine pH will rise, trapping the toxic substance in the urine and flushing it out of the body.
I hit the Enter key hard.
“Nurse Jeong!”
I called over the veteran nurse who happened to be nearby.
“Yes!”
“The order that just went out—the one with Bibon and KCl mixed into 5DW. For now, run the initial 200 cc at full drip and get it in quickly. After that, maintain it at 200 cc per hour. And put in a Foley
(* Foley catheter)
and please check the urine output and urine pH every hour.”
“Yes! I'll hang it right away!”
Nurse Jeong went off to prepare the fluids with practiced ease.
Over there, Baek Eun-seo was on the phone with the nephrology fellow, passionately arguing her case.
I leaned back deep into my chair and let out a sigh.
The patient's breathing was still labored, but now we had a direction.
Until dialysis, this fluid would wash the poison out of the patient's blood.
'At least the immediate fire is out.'
I should study internal medicine more.
If I don't want to be outdone.