Blood Pressure (Part 2)
My utter astonishment lasted only a brief moment.
It was hardly the first time these bastards had caught me off guard with something absurd. Nor was it the first time they possessed knowledge I assumed didn't exist yet—knowledge dating back several centuries, no less. Thanks to that, I regained my composure in short order. Of course, my curiosity still needed satisfying.
"Blundell understands such matters far better than I," Liston remarked, nodding toward his colleague.
"Indeed, indeed," Blundell replied, puffing out his chest. "I am exceptionally well-versed in this realm."
"He didn't fabricate and peddle that 'Rust Bell' or whatever it was called for nothing, after all," Liston teased. "Though by now, it has proven to be an utterly useless contraption..."
"Scientific inquiry is inherently accompanied by failure!"
As expected, it was Blundell who stepped forward to offer a detailed explanation. Liston was always the one who understood people and practical surgery, while Blundell was the repository for scientific history and odd treatises. Today was no exception.
"Now then. To grasp this properly... well, you must already know the basics, I presume. You understand how atmospheric pressure was first measured, do you not?"
Listening to Blundell, my first instinctive thought was: How the hell should I know that? Seeking sympathetic ignorance, I glanced around at the faces in the room with an expectant look, only to be struck dumb. Apparently, everyone in the room knew except me.
Madness... Seriously?
"The tale dates back to the year 1643," Blundell began.
Naturally, being a master at feigning comprehension, I offered a knowing nod as though the story were an old acquaintance. On the inside, however, I was thoroughly shaken. Come to think of it, Robert Boyle had published Boyle's Law around that very era... but knowing a historical fact intellectually is vastly different from feeling its reality firsthand. The nineteenth century felt ancient enough to me, yet they had already accomplished such feats centuries before that? It was genuinely impressive.
"That gentleman utilized mercury to measure the weight of the air. He proved that the force capable of lifting mercury roughly thirty inches was equal to atmospheric pressure. Ever since, anyone who possessed a glass tube sought to measure pressure of every conceivable kind. And because it was right around then that humanity realized the heart pumps blood through pipes known as vessels, they naturally measured blood pressure as well."
They had even measured blood pressure back then! They simply weren't applying it in practice.
When I considered it, their oversight was entirely understandable. In the past, I might have immediately cursed them under my breath as backward, primitive nineteenth-century fools, but these days I possessed immense patience and empathy. Well... how could they possibly know what constitutes normal blood pressure? Terms like hypertension or hypotension couldn't exist without statistical baselines.
I had come to appreciate that without a foundation of broader physiological context, one could not even begin to realize the critical importance of blood pressure.
"Is that so? There is already a method to measure it?" I asked.
"Naturally."
"Then shall we test it at once? Senior Alfred!"
Alfred flinched, waving his hands frantically. "Ah... blood pressure can only ever be measured once in a lifetime, sir."
I paused. I was, after all, a highly competent physician from the twenty-first century. If I began tracking blood pressure in this era, the clinical synergy would be monumental. Yet here was Alfred delivering the most bizarre answer imaginable. Since this was hardly my first brush with historical oddities, I calmly pressed him instead of losing my temper.
"What on earth does that mean?"
"Well, well... you were nodding so knowingly that I assumed you understood, but you had no idea after all, haha!" Blundell chuckled heartily. "Tell me, what is atmospheric pressure? Is it not the force that drives mercury up a slender tube?"
"It is."
"Then what is blood pressure? It is the force driving blood up a slender tube. To measure that, what must one do?"
The first image that sprang to my mind was, of course, the familiar mercury sphygmomanometer. I hadn't taken blood pressure manually since my medical school clerkships, given that automated monitors were ubiquitous in the modern world. But as Blundell described the mechanical principle—the raw force pushing blood up a narrow column—a completely different image crept into my head. The sort of grotesque image one ought never to entertain.
"Don't tell me...?"
"You insert a rigid tube bent at a right angle directly into an artery," Blundell explained matter-of-factly, "and observe how high the column of blood rises."
"Ah..."
Insanity... That's not a diagnostic test, that's a bloody fountain!
Could anyone have actually attempted such a horrific experiment? No, surely not... I thought, but then Liston, the master of gruesome anecdotes, stepped in.
"And what became of that horse?" Liston asked.
"It bled to death," Blundell replied smoothly. "Which is precisely why it is said that blood pressure can only ever be measured once."
"I... I assume no one has attempted this on a human being?"
"Never," Blundell declared. "Not officially, at least."
"Ah..."
Indeed. No matter how unhinged nineteenth-century doctors were, they wouldn't have publicly dared to turn a living human into a spouting geyser just to check pressure. Though, as Liston implied, a few deviants had almost certainly tried it through the back alleys... One might wonder how an educated physician could commit such atrocities, but among the medical practitioners of this era, quite a few were functionally mad scientists—men entirely incapable of distinguishing between saving a life and satisfying their own morbid curiosity.
"So you see, measuring it in practice is absurd," Blundell concluded with a shrug. "Besides, what would one even gain from the knowledge? Aside from satisfying pure curiosity, it serves no therapeutic purpose."
"No, that isn't true."
It absolutely was not true. Blood pressure alone revealed an extraordinary wealth of vital information. If an otherwise stable patient suffered a precipitous drop in blood pressure, it signified massive hemorrhage or severe vasodilation driven by systemic sepsis. Conversely, a sudden spike in pressure indicated extreme physical exertion, agonizing pain, or catastrophic intracranial trauma. It was an indispensable vital sign that painted a comprehensive picture of survival.
Even so, a method that slaughters the patient is completely out of the question.
Could we insert an exceptionally hair-thin cannula...? No, that wouldn't solve the core issue. Mercury and whole blood possessed entirely different specific gravities. Blood was roughly comparable to water, meaning mercury was nearly fourteen times denser. A normal systolic pressure of 120 millimeters of mercury meant a column of blood would erupt nearly two meters into the air! Two meters!
Given the bore of the needles we use, the patient would...
They would die. Even if they survived the initial puncture, they would hover on the brink of hypovolemic shock. Blood pressure wasn't something to measure only on healthy men; we needed it most for critically ill patients. Draining their blood in a two-meter geyser would be outright murder. To risk a patient's life for what amounted to a mere diagnostic test rather than a cure was unacceptable.
How the hell did modern medicine measure it non-invasively...?
Without question, the most direct and accurate way to read pressure was Blundell's barbaric method of puncturing a vessel with a column. But modern medicine didn't butcher patients for a vital sign. If it had, hospitals would still be slaughterhouses echoing with funeral dirges. Someone had invented an ingenious, revolutionary workaround.
I should have gone to engineering school.
If I had known I was going to reincarnate into the nineteenth century, I would have earned a degree in mechanical engineering. Or chemistry. But I hadn't, had I? Regret was the most useless exercise in existence. Anyone who had ever taken a high-stakes exam knew the feeling: when you stare at a problem and have no clue where to begin, agonizing over it for hours never yields the answer. The student who walked out of the testing hall last was never the one who scored the highest.
"What are you brooding over now?" Liston broke into my thoughts, eyeing me suspiciously. "Don't tell me you're contemplating measuring the blood pressure of condemned convicts?"
"No..."
"Wait, hold on," Liston murmured, stroking his chin thoughtfully. "That might actually be a splendid idea. It would certainly make for a tremendous spectacle."
"No, no! Absolutely not!"
A spectacle?! Is that really how a surgeon talks about spewing human blood across a room?! I glared at Liston with deep reproach, but he merely returned my gaze with a look of wounded innocence.
"Why not?"
"Pardon?"
"You were perfectly fine with the arsenic dress experiment, so why balk at this?"
"That... that was conducted to prove to the public that arsenic is lethal poison! We had a righteous justification!"
"Ha-ha! Blood pressure possesses a righteous justification as well! Curiosity! How high would a human blood fountain spurt? How vastly would it differ from that of a horse or a hound?"
Liston delivered the argument with such unvarnished conviction that, for a terrifying second, I was almost swayed. If his expression hadn't resembled that of a deranged mad scientist on the verge of an epiphany, I might have genuinely considered it.
"I confess, I am rather curious about that myself," Blundell chimed in.
With Blundell backing the notion, it was entirely feasible if we chose to pursue it. If the three of us petitioned for it, the Metropolitan Police, Sir James, and the influential grandees of London would readily clear the path. A crimson fountain of human blood... In an era where surgical speed duels in public amphitheaters were treated as thrilling entertainment, turning condemned felons into living blood geysers would probably draw ecstatic cheers from the mob. We could even establish a permanent viewing pavilion in the heart of a London square and turn it into an iconic imperial attraction.
No, get a grip! Why the hell am I visualizing this in such vivid detail?!
My mind was being corrupted by Victorian barbarism. Shaking my head vigorously, I firmly pressed my fingers against my temples, then began massaging my forearm muscles, which had seized up from the strain of our earlier operation. Perhaps under Liston's lingering influence, my physical strength had increased noticeably; I squeezed down on my forearm with enough force to turn the flesh bone-white, yet felt hardly any fatigue in my fingers.
"Hmm. Wait...?"
"What is the matter now?"
The flesh turned white under my thumb. Blanching. Something... there's something right there. A spark flickered at the edge of my memory.
"I asked what is wrong!"
"Brother, be quiet for just one moment."
"Why, you insolent little—"
"Hush, Liston! Quiet yourself!" Blundell hissed urgently, grabbing Liston's sleeve. "Taepyeong is..."
Liston's jaw dropped in reverent horror. "Ah... ahh! The Lord has descended upon him!"
I squeezed my eyes shut. I knew full well that my own intellect alone couldn't invent a device from scratch. Call it recollection or muscle memory—I strained with every fiber of my being to drag forth the knowledge buried deep within my subconscious. It had to be there. Whether overheard during grand rounds or skimmed in a textbook during residency, there was no way I had never learned the underlying physical principle of a blood pressure cuff.
The skin turns pale... because blood flow is halted...
True, I had never formally studied the mechanical engineering of a sphygmomanometer. But when combined with modern physiological concepts, deducing the answer was infinitely easier than a nineteenth-century physician stumbling blindly in the dark.
If the skin blanches, it means the external pressure I exert exceeds the pressure within the vessel, collapsing it. The vessel's ability to resist collapse is governed entirely by the internal pressure of the blood pushing against its walls. Which means...
The pieces clicked into place.
Yes, that's it! When taking blood pressure, you wrap an inflatable cuff around the upper arm and pump it tight. Why do you tighten it? To temporarily cut off the arterial pulse! And why occlude the artery in the first place?
The external pressure required to halt the arterial blood flow corresponds precisely to the patient's internal blood pressure! That's the entire trick!
Holy shit... I really am a genius.
Even with future medical knowledge, I had never deliberately studied the engineering history of a cuff, yet here I had solved the entire puzzle simply by massaging my cramped forearm. Could anyone ever believe such absurd brilliance?
"Heh... heheh."
"Is... is that the Lord speaking as well?" Liston whispered, his voice trembling. "It sounds remarkably like the cackle of Satan himself."
"Have you ever heard the Lord laugh?!" Blundell snapped in an anxious undertone. "How would you know what He sounds like?!"
"Still, the divine possession is lasting unusually long today..."
"Has his spiritual communion deepened in the interim?"
Laughter bubbled up helplessly from my chest. Bizarre theological nonsense buzzed around my ears, but I couldn't care less. Well, actually, I did care. If only these bastards possessed an ounce more scientific literacy, I could have openly bragged about my transcendent intellect! The fact that I had to hoard this glorious revelation to myself because they were ignorant savages was an absolute tragedy.
Regardless, I snapped my eyes open.
"We must fabricate a mercury sphygmomanometer at once."
"H-has He departed?" Liston stammered.
"Who? Ah, the Lord?"
"Aye!"
"He has departed. But He has bestowed upon me a divine revelation. We have no need to plunge glass pipes into living vessels... Go quickly, and drag every skilled blacksmith and precision instrument maker you can find straight to me."
Liston slammed a massive fist over his chest, his eyes burning with holy fervor.
"In the name of my Lord, I swear I shall drag them here without fail!"