185: The conclusion in Chapter 185 is more accurate than what I gave before.
Professor Luo Zhenyu's hand paused on the remote control, and he turned to look at him.
"Oh?"
"You just said that no one discovered that critical window period."
"Yes."
"I found it."
The atmosphere in the classroom changed in an instant.
Professor Luo Zhenyu put down the remote control, faced Lu Chen, and pushed up his glasses.
"Speak."
Lu Chen did not answer directly; instead, he walked to the whiteboard on the side of the classroom and picked up a marker.
He wrote four sets of numbers on the whiteboard.
Upon admission: Calcium ion 1.08 mmol/L
1 hour post-operation: Calcium ion 0.97 mmol/L
2 hours post-operation: Calcium ion 0.82 mmol/L
3 hours post-operation: Calcium ion 0.71 mmol/L
After writing the four numbers, Lu Chen drew a horizontal line between the second and third ones.
Then he turned around to face the entire room.
"This is the serum free calcium concentration recorded in the medical record."
"1.08 upon admission is already on the low side, but it is still within a range that can barely be compensated."
"It dropped to 0.97 one hour post-operation. Considering the effect of citrate chelating calcium ions during massive blood transfusion, this rate of decline is within expectations."
"But here."
Lu Chen pointed to the segment from 0.97 to 0.82.
"From one hour post-operation to two hours post-operation, the calcium ion plummeted from 0.97 to 0.82 within one hour."
"This rate of decline is not normal."
"If it were only the effect of citrate chelation, it wouldn't be this fast."
"This indicates that during this time period, besides the calcium loss caused by massive blood transfusion, there are other factors consuming calcium ions."
"I checked other data for the same time period."
Lu Chen wrote a few more numbers on the whiteboard.
2 hours post-operation: Blood phosphorus concentration 2.41 mmol/L (significantly elevated)
2 hours post-operation: Blood potassium concentration (significantly elevated)
2 hours post-operation: pH 7.12 (further decline)
"Elevated blood phosphorus, elevated blood potassium, decreased pH, and a sharp drop in calcium ions."
"In the context of severe trauma, the simultaneous abnormal changes in these four indicators point to the same pathological process."
Lu Chen paused for a moment.
"A comminuted pelvic fracture led to extensive bone tissue fragmentation and bone marrow extravasation."
"Under acidic conditions, intraosseous calcium phosphate releases a large amount of phosphorus."
"The elevated phosphorus binds with calcium in the blood to form calcium phosphate deposits, further consuming the already insufficient free calcium."
"At the same time, necrotic muscle tissue and lysed bone marrow cells release large amounts of potassium ions and phosphorus, accelerating electrolyte disturbance."
"This is not simple transfusion-related hypocalcemia."
"This is trauma-related calcium-phosphorus metabolic disorder superimposed on transfusion-related hypocalcemia, leading to an extremely dangerous complex electrolyte imbalance."
The classroom was silent.
Everyone was digesting what Lu Chen had said.
Professor Luo Zhenyu pushed up his glasses, and his gaze changed.
"Continue."
"When the free calcium concentration drops below 0.82, myocardial contractility will significantly decrease, and peripheral vascular tension will also further decrease."
"Combined with the direct inhibition of myocardial cells by acidosis, the circulatory system has already begun to decompensate at this point in time."
"The disseminated intravascular coagulation (DIC) that appeared 4 hours post-operation is also related to this."
"Hypocalcemia itself affects the activity of coagulation factors, compounded by the dilutional coagulopathy caused by massive blood transfusion."
"The collapse of coagulation function between 2 and 4 hours post-operation is almost inevitable."
"But if this inflection point of sharp calcium ion decline at 2 hours post-operation had been discovered in time…"
Lu Chen put the marker back on the whiteboard tray.
"Targeted intervention at that node: while continuously pumping high-concentration calcium chloride intravenously to supplement calcium, initiate continuous venovenous hemofiltration (CVVH) with citrate chelation, using low-calcium dialysate combined with citrate anticoagulation."
"The benefits of this mode are twofold."
"On one hand, CVVH can remove excess phosphorus, potassium, and inflammatory mediators, slowing down the vicious cycle of electrolyte disturbance at the source."
"On the other hand, the citrate anticoagulation mode will not worsen hypocalcemia; instead, it can precisely regulate the supplementation rate of calcium concentration during the extracorporeal circulation process."
Lu Chen paused.
"If this plan had been initiated in time at that inflection point 2 hours post-operation, based on a retrospective analysis of the laboratory data at that time…"
"The patient's collapse of coagulation function at 4 hours post-operation could have been delayed or even partially prevented."
"Once coagulation function is stabilized, the subsequent DIC would not have arrived so quickly."
"If DIC doesn't set in, the microcirculatory damage to the kidneys and liver would not be so severe."
"The progression of MODS could have been slowed down."
"Of course, I am not saying this plan would definitely have saved him."
Lu Chen looked at Professor Luo Zhenyu.
"With such severe multiple injuries, there are too many variables; a problem at any link could lead to irreversible results."
"But if intervened in time at that inflection point, I believe the possibility of reversal is around 13%."
"Not high, but not zero."
...
The classroom was silent for a long time.
It was the kind of silence where everyone was thinking.
Professor Luo Zhenyu looked at the sets of numbers on the whiteboard and did not speak for a while.
After about fifteen seconds, he slowly took off his glasses, wiped the lenses, and put them back on.
"You are the first to notice this calcium ion inflection point."
His voice was a little lower than before.
"I have given this medical record to no fewer than ten groups of students to review."
"Everyone before, including some senior Associate Chief Physicians, had their attention entirely focused on the surgical strategy and blood transfusion strategy."
"No one had ever carefully looked at that set of electrolyte follow-up data."
"Even I, when reviewing this case for the first time, did not realize this abnormal inflection point of calcium ions."
"It was only later, after inviting experts from the Endocrinology and Nephrology departments to review it together, that we discovered this problem."
Professor Luo Zhenyu looked at Lu Chen.
"Regarding the CVVH plan you just mentioned, I have also discussed it with experts from the Nephrology department, and the conclusion is similar to yours."
"Theoretically, if one intervenes during that window period, there is indeed a certain possibility of reversal."
"As for the specific probability, our estimate at the time was 10% to 15%."
"You said 13%, which is within this range."
He paused.
"I need to modify my previous conclusion."
Professor Luo Zhenyu walked back to the podium and wrote a line of text on the small whiteboard next to the screen.
"Under current technical conditions, if the electrolyte abnormality inflection point at 2 hours post-operation can be identified in time and targeted CVVH intervention is initiated, there is about a 10% to 15% possibility of reversal in this case."
After finishing, he turned around.
"This conclusion is more accurate than what I previously provided."
He looked at Lu Chen.
"What is your name?"
"Lu Chen."
"Which Hospital are you from?"
"Jiangcheng City Central Hospital, Emergency Department."
Professor Luo Zhenyu gave a hum of acknowledgment.
"Lu Chen."
He repeated the name.
"Your clinical thinking is very solid; it's not something learned by rote, but honed through practical experience."
"The ability to grasp key signals from complex data noise is not something that can be trained solely by textbooks."
"You did it."
"Very good."
He didn't say anything more and turned to pack up the materials on the podium.
But all the students present understood the weight of the words "very good" when spoken by Professor Luo Zhenyu.
This professor is famous in the Emergency Department academic circle for being strict; being able to get a "not bad" after a class is already a huge affirmation for a student.
No one present had ever heard him say "very good" to a student before.