Brain aneurysm
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Still haven’t figure out what “LaPlace wins” means in this context, but I found a cool YouTube video showing 360° VR view of a surgery to repair a brain aneurysm … watch it on your smartphone or tablet so you can actually pan around the 360° view. Cool that I stumbled this YouTube VR feature while looking for videos showing brain aneurysm repair surgeries.
Link to video -
Still haven’t figure out what “LaPlace wins” means in this context, but I found a cool YouTube video showing 360° VR view of a surgery to repair a brain aneurysm … watch it on your smartphone or tablet so you can actually pan around the 360° view. Cool that I stumbled this YouTube VR feature while looking for videos showing brain aneurysm repair surgeries.
Link to video@Axtremus said in Brain aneurysm:
till haven’t figure out what “LaPlace wins” means in this context,
LaPlace's law says that the tension across a sphere (or a cylinder) is proportional to the diameter at a constant pressure.
So, if you keep pressure constant, and double the diameter, you double the wall tension. Ultimately that tension exceeds the ability of the vessel wall to remain stable, so it ruptures.
By reducing the diameter of the sphere (aneurysm), you reduce the tension on the vessel wall, hopefully preventing it from rupturing (again). Presumably, this has happened in this patient in the past - else, how would you know the diagnosis? So this surgery is designed to prevent it from happening again.
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This is a very challenging procedure for the anesthesiologist. As I said, the tension on the vessel wall is related to the pressure inside the wall, If the pressure (the blood pressure) increases, the risk of the aneurysm rupturing goes up as well.
To facilitate the placing of the aneurysm clip, it helps the surgeon (a lot) if you can make the vessel wall "soft." By lowering the blood pressure, you can make the wall "soft" and make placing the clip easier, safer, and with a lower risk of rupture when the clip is placed. Think of the challenge of "pinching off" a piece of balloon - if the balloon is soft, it's easier and safer to do.
So, the concept of "controlled hypotension" became popular. The idea was to lower the BP so much that the aneurysm is soft and the clip is easily applied. Of course, there is a potential hazard. If the BP is lowered too low, and for too long, one risks the delivery of oxygen to the brain and other vital organs. No blood pressure = no blood flow.
It was a delicate, hazardous dance that we did.
Never enjoyed those cases....
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I distinctly remember a conversation I had with a senior attending gas-passer one Saturday morning (we were both on call).
Me; So, Larry, tell me about controlled hypotension.
Larry: Yeah??
Me: How low will you take the BP?
Larry: Zero
Me; What???
Larry: Yeah. I'll take it down to zero for a few seconds. If I trust the surgeon. That's the point, you have to trust him and he has to trust you. So, when he says, "Larry, are you ready?" I say, "Yeah, I am."
"OK, take it down."
"Doing it now...pressure is 100...70...50...20...OK Ed, put the clip on ... right NOW."
"OK Larry, clip is on...bring it up..."
Me: That really happens?
Larry: Indeed. It's called "Teamwork."
And about 3 years later, I worked with Ed, and we danced that dance.
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I distinctly remember a conversation I had with a senior attending gas-passer one Saturday morning (we were both on call).
Me; So, Larry, tell me about controlled hypotension.
Larry: Yeah??
Me: How low will you take the BP?
Larry: Zero
Me; What???
Larry: Yeah. I'll take it down to zero for a few seconds. If I trust the surgeon. That's the point, you have to trust him and he has to trust you. So, when he says, "Larry, are you ready?" I say, "Yeah, I am."
"OK, take it down."
"Doing it now...pressure is 100...70...50...20...OK Ed, put the clip on ... right NOW."
"OK Larry, clip is on...bring it up..."
Me: That really happens?
Larry: Indeed. It's called "Teamwork."
And about 3 years later, I worked with Ed, and we danced that dance.
@George-K said in Brain aneurysm:
I distinctly remember a conversation I had with a senior attending gas-passer one Saturday morning (we were both on call).
Me; So, Larry, tell me about controlled hypotension.
Larry: Yeah??
Me: How low will you take the BP?
Larry: Zero
Me; What???
Larry: Yeah. I'll take it down to zero for a few seconds. If I trust the surgeon. That's the point, you have to trust him and he has to trust you. So, when he says, "Larry, are you ready?" I say, "Yeah, I am."
"OK, take it down."
"Doing it now...pressure is 100...70...50...20...OK Ed, put the clip on ... right NOW."
"OK Larry, clip is on...bring it up..."
Me: That really happens?
Larry: Indeed. It's called "Teamwork."
And about 3 years later, I worked with Ed, and we danced that dance.
Holy balls.
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Nice descriptions.
Every surgical resident knows laplace’s law.
It explains why when there is an obstructing carcinoma of the left colon, it’s the cecum on the right that will perforate. Diameter of the cecum is the largest in the colon. The obstruction causes a closed loop and the tension on the wall of the cecum increases past the point of containing and becomes ischemic and eventually bursts.
So…Obstructed colon. Pain in the right lower abdomen. Ominous sign. Laplace. T=PR. Tension equals pressure times radius. I expect the residents to know that from the moment they start seeing patients in the ER.
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There was a while when also trauma management involved controlled hypotension. Don’t bring up the pressure so much that u actually increase bleeding.
I think it’s fallen out of practice because it’s clinical utility was never really proved.
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There was a while when also trauma management involved controlled hypotension. Don’t bring up the pressure so much that u actually increase bleeding.
I think it’s fallen out of practice because it’s clinical utility was never really proved.
@bachophile we had an oral surgeon who was very much into reconstructive surgery. And by reconstructive, I don't mean pulling teeth that were in the wrong place. I mean he would fix prognathism, do LeForte reconstructions (that's where you separate the upper jaw from the base of the skull and move it around) etc.
These patients were usually young (late teens and into their 20s) and healthy. Besides the airway challenges, blood loss was a major consideration. It was not unusual to have to transfuse these patients at least 1 unit.
When we started using controlled hypotension (MAP ~ 40) blood loss became a non-issue. I don't know if it was ever studied elsewhere, but our experience showed it to be useful.
We also had a few orthopedic surgeons who liked it for hip replacements and for Harrington rod instrumentations.
As I said, I don't know if it's fallen out of favor since then, so ymmv.
