Why Do You Know This (End)

“Hoh…?”

Professor Hwang Jun stared straight at me.

“I didn’t expect to hear you mention high-frequency ventilation, Dr. Han. That’s not a machine your department uses. You know about that?”

Crap.

A chill ran down my spine.

An emergency medicine resident discussing the indications for a neonatal ventilator, a subspecialty in neonatology?

And in front of a professor, no less?

This was like a first-year resident telling a professor on rounds, “According to the latest paper, wouldn’t it be better to use this drug?”

I got too full of myself.

Even the example I brought up could be argued as being within the same department, but this was outright encroaching on another specialty.

I'm screwed.

I should’ve just stayed quiet and left.

I should’ve just peeked at the nursing chart, then muttered with the ghost about why it happened and satisfied my curiosity that way.

Why did I have to use my mouth and stir up trouble when I could’ve checked a tiny computer screen instead?

Watching the strange smile spread at the corner of Professor Hwang Jun’s lips, I had a bad feeling.

I wasn’t going home cleanly today.

“Yes, as you said, it’s currently set to SIMV(* synchronized intermittent mandatory ventilation) mode. But do you happen to know why HFOV(* high-frequency oscillatory ventilation) should be considered first in a case like this, with meconium aspiration?”

Professor Hwang asked me with a very pleased expression.

'Ah, this is...'

If I combined what I had roughly picked up during my resident and intern days from all over with the hint the ghost had given me while preparing for today’s deployment, the answer was obvious.

Probably.

If my memory was correct, that is.

“Ah, yes. I think it’s because of the risk of pneumothorax(* collapsed lung). Standard positive-pressure ventilation pushes in high pressure all at once, so there’s a high risk of rupturing the airway blocked by meconium. On the other hand, HFOV can minimize lung damage, so I believe that’s why it’s recommended.”

This should be right, shouldn’t it?

Please.

“It also has the advantage of keeping alveoli stably open while avoiding hypoxia and hyperventilation at the same time.”

“Yes. Correct. Textbook.”

Professor Hwang nodded.

So this is where all that hard studying pays off... right?

At this point, he’d be satisfied and stop asking, wouldn’t he?

But to my unease, the subtle smile on Professor Hwang’s lips didn’t disappear.

If anything, it seemed to deepen.

“But then why didn’t I use HFOV on this baby? If what you say is true, that would be the better choice. Go on, tell me.”

“Ah...”

'Tell you what? I’m not even one of the residents in your department, you damn bastard.'

I debated cursing inwardly, then held back.

No, does it even make sense to ask a third-year emergency medicine resident about detailed NICU ventilator strategy?

Are you asking the guy who delivered your jjajangmyeon to lecture you on the fermentation science of black bean paste?

But if I say, “I don’t know,” here, the situation will get weird.

On top of the genius image that had been pinned onto me so far, and more importantly, I had just pretended to know things earlier.

I quickly turned my eyes and brought up the blue window floating in the air.

Savior, answer me.

HellJoseonSlave1: This guy knows HFOV would be better but didn’t use it. What the hell? Is this a sting operation? What’s the reason?

ㄴ PediatricGhost77: Hmm. Usually they do use it... then maybe the meconium was too sticky, or maybe air trapping(* trapped air)

was a serious concern. Or maybe the vitals were bad or something.

Even the ghost looked a little flustered.

ㄴ PediatricGhost77: Maybe the blood pressure was bad? HFOV keeps intrathoracic pressure high, which reduces blood returning to the heart, so the baby’s BP can drop.

Ah!

I slapped my knee.

Well, not literally.

Hemodynamic instability.

This was it.

That had to be the answer.

It was a logic tied to the vitals, which are the most important thing to me as an emergency physician.

'Okay, I can work with this.'

I cleared my throat and opened my mouth with a very serious expression.

“Um... ah... in my opinion, I believe it was because the patient had severe hemodynamic instability during initial resuscitation.”

“Hemodynamically unstable?”

Professor Hwang crossed his arms and looked at me with interest.

“Yes. During delivery and while securing the umbilical venous catheter, the infant may have been in a state close to hypovolemic shock or cardiogenic shock. The myocardium was already weakened by hypoxia, and pulmonary hypertension was also present.”

I dressed up the keyword the ghost had thrown at me with a layer of my own knowledge and wrapped it in something that sounded convincing.

This actually makes sense, doesn’t it?

“In that case, if HFOV were applied improperly and the mean intrathoracic pressure became too high, venous return would decrease and cardiac output would plummet, causing blood pressure to drop catastrophically. I imagine you chose SIMV to prioritize blood pressure stability so as to maintain the immediate perfusion pressure.”

Perfect.

I even felt proud of myself.

“Hmm? So that’s what you were thinking.”

Professor Hwang stroked his chin.

“Makes sense. As expected from emergency medicine; that approach is quite good. Nice reasoning.”

He smiled faintly.

“But you’re a little off.”

“Pardon?”

Wrong?

At that moment, a new comment appeared in the floating window.

ㄴ PediatricGhost77: But come to think of it, if you tweak the MAP setting a bit and give more fluids, the BP issue should be fixable, so maybe not that one. Sorry lol.

'Then you should’ve said that sooner.'

I forced myself to keep a calm expression.

Well, if this was a question even PediatricGhost77 couldn’t give a clear answer to, it wouldn’t be strange that I couldn’t answer it either.

Probably.

“Ah... yes. Is that so.”

“You’re not wrong. A drop in blood pressure is scary. But that’s something you can manage with vasopressors and fluids.”

Professor Hwang pointed at the X-ray on the monitor with a finger.

“I judged the risk of air trapping to be greater. The meconium looked too viscous. I was worried that the rapid oscillations of HFOV would either push the meconium deeper into the alveoli or cause air to get in but not out, making the lungs burst like a balloon.”

“So that was it...”

“Anyway, your attempt was good.”

Professor Hwang looked at me with amusement and pulled his chair in closer, straightening his posture.

“Then last question.”

He narrowed his eyes.

“If that’s the case, then as you said, in this situation with the risk of pneumothorax, if you were to use SIMV mode... how exactly would you set it so the baby’s lungs don’t go pop?”

This is the real game.

He’s asking for specific numbers.

This isn’t something you can brush off with vague talk.

Cold sweat broke out.

I can set adult ventilators with my eyes closed now, but neonates are different.

For adults, RR is usually set to 12–16 breaths per minute, but for newborns I know it’s set at 30–60.

But in the case of meconium aspiration?

“...Ah, just a moment please. I’m not very familiar with the default settings of the machine we use in our hospital’s... NICU, so would it be alright if I simulate it in my head for a moment?”

'That’s complete gibberish.'

Even as I said it, it sounded a little embarrassing.

“Take your time and think it through.”

Professor Hwang crossed his arms and stared straight at me.

'This pressure is driving me crazy.'

I rolled my eyes and looked back at the gallery.

Come on, Pediatrics Ghost, please get this one right.

ㄴ HellJoseonSlave1: He’s even asking for specific SIMV values. Damn, isn’t this workplace harassment? Why is he doing this to a different department’s resident?

ㄴ PediatricGhost77: What do you mean workplace harassment? He’s just a good boss trying to teach you.

ㄴ PediatricGhost77: You need to give the exhalation time longer. Lower the respiratory rate to about 30 breaths per minute. Much slower than a typical newborn.

ㄴ PediatricGhost77: The I:E ratio

(* inspiratory-to-expiratory ratio)

should be around 1:3. E

has to be much longer. That gives the inhaled air time to get out.

ㄴ HellJoseonSlave1: When there’s air trapping, the ratio is the same as in adults.

ㄴ PediatricGhost77: Yeah. If you give 1:2, the air won’t fully escape and the lungs will burst. You should be looking at 1:3, maybe even 1:4.

ㄴ PediatricGhost77: And PIP

(* peak inspiratory pressure)

should be around 25. You can’t hit them too hard. PEEP

(* positive end-expiratory pressure)

should be maintained around 4 to 5.

Okay.

This time for sure.

I took one deep breath and lifted my head.

“I’ve got it sorted out.”

“Oh? Tell me.”

“First, the key is to secure enough expiratory time to prevent air trapping. Therefore, I would set the respiratory rate lower than that of a typical newborn, at around 30 breaths per minute.”

Professor Hwang’s eyes widened.

“And the most important inspiratory-to-expiratory ratio would be 1:3, and if necessary, I’d make the expiratory time even longer so the inhaled air can fully escape.”

Son Jongun looked stunned.

“To prevent pressure injury, I’d limit PIP to no more than 25, and keep PEEP at around 4 to 5, just enough to prevent alveolar collapse.”

Another silence settled over the room, and the only sound in the conference room was the computer fan spinning.

Professor Hwang stared at me with his mouth half open.

He didn’t even seem to realize his glasses had slid down to the tip of his nose.

“Huhhh...”

Professor Hwang ran a hand through his hair.

“Hahaha, good grief. This... wow.”

Professor Hwang took off his glasses and set them on the desk, bursting out laughing in disbelief.

“So Son Jongun wasn’t bluffing after all. There really was a monster hiding here.”

Well, as a ghost, I guess monster-adjacent is technically right.

Ah.

I don’t know anymore.

I just want to go home.