“Mr. Minho!”
Taeho and Gihwan hurriedly pulled Heo Minho up onto the boat.
Heo Minho lay limp and unconscious.
Gihwan shouted in panic.
“What happened? I’ll call 119!”
“The Coast Guard comes before 119. I suspect decompression sickness.”
“Decompression sickness?”
“It’s diving sickness caused by a rapid ascent. A regular hospital won’t help.”
Taeho examined Heo Minho with Bio Vision. It was a shocking sight.
Silver bubbles were drifting through the blood vessels all over his body. Nitrogen bubbles. Red emboli were visible in the cerebral vessels, and the pulmonary vessels were the same. The strands of light leading to the central nervous system were going out one by one.
“We need a decompression chamber right now!”
Taeho said urgently.
Kim Daesu climbed up belatedly as well. When he saw Heo Minho’s condition, his face turned deathly pale.
“What do we do! This is my fault! I should’ve kept a proper eye on him!”
Seong Gihwan was making the call.
—Coast Guard 124 Situation Room.
“We have an emergency patient! Diver with decompression sickness, requesting transport to a decompression chamber!”
—What is your current location?
“We’re off the coast of Samcheok, but… the exact location is…”
The captain quickly took the phone.
“37 degrees 25 minutes north, 129 degrees 10 minutes east!”
—Confirmed. Helicopter is being dispatched. Estimated arrival in ten minutes!
In Heo Minho’s current condition, even ten minutes was too long.
Taeho began emergency treatment.
“Mr. Kim, you have a diving oxygen tank, right?”
“Here!”
Taeho placed a high-concentration oxygen mask on Heo Minho. Then he tilted his body to the left and lowered his head.
“This position helps prevent the bubbles from going to the heart.”
The captain of the Merry watched from beside them and asked anxiously.
“The money… how much will the treatment cost?”
“The helicopter dispatch alone will probably be several million won. If you include decompression chamber treatment…”
“Money is money, but a man’s life is a man’s life, ain’t it!”
When Kim Daesu glared at the captain with his bulging eyes and drove the point home, the captain retreated without a word.
At that moment, Heo Minho suddenly began convulsing.
Through Bio Vision, Taeho saw that the bubbles in his cerebral vessels were growing larger.
The bubbles that had initially been the size of grains of rice were now swelling to the size of small beads, beginning to block the major branching points of the cerebral vessels. In particular, blood flow near the middle cerebral artery was almost completely cut off, and the area was turning dark.
‘Convulsions this severe mean the cerebral embolism has progressed considerably. It looks like this isn’t simple decompression sickness, but arterial gas embolism as well.’
Heo Minho’s body arched like a bow, then stiffened straight again, over and over. More and more foam flowed from his mouth. It was increased secretion caused by airway edema.
Taeho quickly raised Heo Minho’s head by about thirty degrees. He needed to improve venous return and lower intracranial pressure even a little.
As his breathing became irregular from the convulsions, the oxygen supply to his brain worsened further. A vicious cycle had begun.
“Captain. If there’s an emergency kit here, bring it quickly!”
“Yes.”
The captain hurried to a corner of the wheelhouse and brought out an old emergency kit. When he opened the lid, all it contained were bandages, gauze, iodine, and a few fever reducers.
“This is all there is, Director.”
Taeho’s brow furrowed.
There was nothing useful.
Taeho touched his glasses and whispered.
“Rema, search for emergency treatment protocols for decompression sickness.”
—Searching…
—There are no protocols applicable to the current situation. I will link to the Asclepius database and search for alternatives.
—Near-future acoustic medicine technique discovered: noninvasive bubble fragmentation using specific frequencies.
—Alternative therapy using a portable vibration-generating device is possible.
A portable vibration-generating device?
Could this work too?
Taeho took out his smartphone.
—Utilizing smartphone vibration motor. Generating vibration pattern equivalent to 28.5 kHz. Critical patient biometric data analysis complete.
—It is possible. The haptic motor in a modern smartphone can produce more precise vibrations than expected. The issue is the exact frequency and location.
—Rema AI will connect to Kang Taeho’s smartphone.
An app with the Rema logo appeared on the phone screen.
Taeho tapped the app and launched it.
A frequency graph appeared on the screen.
While precisely identifying Heo Minho’s blood vessels with Bio Vision, Taeho placed the smartphone in the exact position.
—Optimal location confirmed. Beginning vibration pattern.
The smartphone began vibrating so faintly it could barely be felt. Unlike an ordinary vibration, it was an extremely precise and rhythmic pattern.
When Taeho observed through Bio Vision, something astonishing was happening. The large nitrogen bubbles inside the blood vessels were resonating with the vibrations and breaking down into smaller and smaller bubbles.
—Bubble decomposition progress: 67%. Patient vital signs improving. Reduced vascular resistance confirmed.
Gihwan stared closely at the smartphone screen, then widened his eyes.
“Director, what are you doing right now? This vibration pattern… it isn’t ordinary haptic feedback, is it?”
Kang Taeho was briefly flustered by Gihwan’s sharp observation, but he answered calmly.
“It’s the physics of vibration. If you make the bubbles resonate at the correct frequency, their surface tension weakens and they naturally break apart.”
“But how do you know the exact frequency? The size and location of the bubbles in a decompression sickness patient would all be different.”
Gihwan kept digging. As expected of a genius scientist, he had struck at the core of it.
Kang Taeho hesitated briefly, then said,
“Hmm. After identifying the size and density of the bubbles with Bio Vision, I applied fluid dynamics formulas and calculated it.”
“Don’t tell me you’re doing those complicated calculations in your head right now?”
Gihwan looked as if he found it hard to believe.
“It isn’t that difficult to back-calculate the bubbles’ resonant frequency using a combination of Reynolds number and Weber number.”
Taeho spoke as if it were only natural, but inwardly, he was grateful for the data Rema was providing in real time.
Gihwan’s expression shifted from curiosity to shock.
“Hah… Director. Are you really human?”
“So far, yes.”
Taeho answered with an awkward smile.
Meanwhile, color slowly began returning to Heo Minho’s face.
Gihwan said in admiration,
“I thought it was theoretically possible, but seeing it in real life is truly amazing.”
“Mr. Gihwan, you’ve thought about something like this too?”
“When I was researching seaweed extracts, I used ultrasonic treatment a lot. I knew specific frequencies were effective for disrupting cell walls. But I never thought to apply it to the human body.”
Kim Daesu, who had been listening intently to the conversation from beside them, shook his head.
‘What’re they even saying? I can’t understand a lick of it. Still, well, looks like that damn fool’s getting better.’
Five minutes later, Heo Minho’s convulsions stopped, and he began regaining consciousness.
“Ugh… Where am I…”
“You damn fool! You finally coming to your senses?”
Kim Daesu shouted loudly in joy.
Tat-tat-tat-tat!
The sound of a helicopter came from afar.
When Taeho looked through Bio Vision, the bubbles in the cerebral vessels had decreased significantly, and the inflammatory response in the vascular endothelium was also being suppressed.
Gihwan looked at Taeho with shining eyes and said,
“Director. This is revolutionary. Breaking down bubbles inside blood vessels with sound waves…”
“It isn’t complete yet. Decompression chamber treatment is still necessary. But we were able to prevent acute-phase damage.”
The captain shouted into the radio.
“Calling Coast Guard 512, calling Coast Guard 512.”
Ten minutes later, the sound of rotors approached from beyond the horizon, cutting through the sea.
—Merry, Merry. This is Coast Guard 512. Please report patient status. Conscious, but severe respiratory distress. A doctor is with him.”
The helicopter began hovering thirty meters above the vessel. The rough rotor wind churned the sea. A rescuer descended by winch and stood in front of Taeho.
“Are you the doctor?”
“I’m Kang Taeho. The patient is suspected of decompression sickness. He needs immediate hyperbaric oxygen therapy.”
As the rescuer secured Heo Minho to the stretcher, Taeho also put on a harness and was connected to the winch with him.
“Director, I’m counting on you.”
“Yes. Don’t worry.”
The sea grew distant, and the helicopter cabin came into view.
“Blood pressure 90 over 60, pulse 110, respiratory rate 28, SpO₂ 92%.”
The paramedic reported.
“Switch to a reservoir mask, flow rate 15 L/min. Maintain 100% oxygen.”
Taeho checked the oxygen mask himself.
“Establish an 18G line and start 500 ml of normal saline. Correcting dehydration is important.”
He put a stethoscope in his ears.
“Breath sounds are maintained bilaterally, but there are slight bubbling sounds. No neurological symptoms yet. Continue monitoring.”
When Taeho activated Bio Vision, he could see minute bubbles inside the blood vessels glittering like silver dots as they flowed. Fortunately, they had not yet reached the cerebral vascular system.
“Fifteen minutes to Busan Naval Hospital.”
At the pilot’s report, Taeho nodded.
“We need to maintain blood flow and oxygen supply at the maximum until then.”
Taeho held Heo Minho’s hand and said,
“You’ll be all right. Hold on just a little longer.”
Heo Minho’s pulse seemed to stabilize a little more.
The helicopter continued flying toward the skies above Busan. Below, the blue sea stretched endlessly.
***
“Emergency patient coming in!”
As they entered the emergency room, a Navy medical team was waiting.
Taeho gave a concise handover.
“Male, twenty-nine years old. Rapid ascent from a depth of thirty meters without decompression stops. Chest pain and dyspnea occurred immediately after surfacing. Administered 100% oxygen on-site and inside the helicopter, 500 ml fluids given. Current vitals: 100 over 65, HR 96, RR 22, SpO₂ 98%.”
The team leader nodded.
“We’ll transfer him directly to the decompression chamber. Doctor. Unfortunately, due to military regulations, outside medical personnel cannot accompany him inside the chamber.”
“Then I’ll monitor from outside and advise you.”
“Thank you. We’ll communicate through the intercom if necessary.”
A Navy medic checked Heo Minho’s mask and oxygen flow again.
“Beginning ascent to 3 atmospheres of pressure.”
Shhh—shhh—
Through Bio Vision, Taeho could see the bubbles inside the blood vessels being compressed and shrinking in size.
After three hours, the first decompression was performed, and after six hours, the final decompression took place. They maintained 1.3 atmospheres for thirty minutes, then returned to normal atmospheric pressure.
Taeho waited patiently, observing.
Through Bio Vision, he saw only a few tiny residual bubbles remained, at a level that could be naturally absorbed.
Only then could Taeho feel relieved.
The chamber door opened slowly. The air after the long treatment mixed with the outside air all at once, giving off a subtly sweet scent.
Taeho first took Heo Minho’s wrist and checked his pulse, then asked,
“Do you feel dizzy or nauseous?”
Heo Minho caught his breath for a moment, then shook his head.
“I’m fine. Breathing feels easy too.”
Taeho gave the nurse a look.
“Please check orthostatic blood pressure once.”
When the patient raised his upper body from the bed, the medical staff supported his arm beside him. After confirming that his systolic pressure remained stable, Taeho nodded.
“Let’s try standing up slowly. One step at a time, don’t push yourself.”
With the medical staff supporting him, Heo Minho took a step.
Two steps, three steps… His gait was stable.
“Good. No problem walking. Still, get plenty of rest today, and absolutely no overexertion or diving within twenty-four hours.”
“Yes, understood.”
When Taeho made one final check with Bio Vision, only clear, uninterrupted blood flow was moving through the vessels. Taeho let out a short breath and said,
“It looks like you’ve fully recovered. From now on, make sure you follow a safe diving plan. You were lucky today, but there’s no guarantee you will be next time.”
“Thank you so much, Doctor. You saved my life.”
Heo Minho bowed deeply. Taeho smiled lightly and patted his shoulder.
Gihwan and Kim Daesu, who had arrived late, came in together.
Tears welled at the corners of Kim Daesu’s deeply wrinkled eyes.
“You all right now?”
Kim Daesu took Heo Minho’s hand. The diver’s rough hand was trembling.
Heo Minho choked up.
“Hyungnim, I’m sorry. I got too greedy.”
“You idiot… No, I should’ve looked after you better.”
Kim Daesu turned and bowed his head toward Taeho.
“Director. Thank you so very much for saving this lad.”
It was the sincerity of a man who had lived his entire life alongside the sea.
“It’s what I should do as a doctor. Thankfully, he recovered without any aftereffects.”
Taeho said in relief.
In the corridor after leaving the hospital room, Taeho looked out at the sea beyond the window and said,
“Mr. Gihwan, after what happened today, I’ve got a lot on my mind.”
“What kind of thoughts?”
Gihwan’s eyes widened.