NOsaintsfan

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New CA1 here had a case the other day that still has me wondering what happened.

56 yo male, history of HTN and B-cell lymphoma comes in for a neck dissection/lymph node biopsy.

Patient was induced uneventfully with 120mg propofol, 50 of fentanyl and succinylcholine. No BP issues at this point.

Placed a cobra ETT and the plan was to keep the patient on the deeper side as the surgeon doesn't want the patient paralyzed.

I get the patient to 1.1 MAC and give 50 of fentynl just before incision. Prior to this the BP had been in the 110's.

Within 1 minute his BP tanks and his MAP falls to the 50's. Over the next few minutes I try giving phynlephrine, ephedrine even levophed with no/minimal response. I reduce the gas to 0.8 MAC and hes still hypotensive and nothing is working. Finally I ended up giving epinephrine and was able to get his BP back up.

I ended up having to give intermittent bonuses of epi 1mcg at a time as he wouldn't respond to anything else.

My attending was in the room by the time I was giving levophed and epi and he was thinking it was an adverse reaction to possibly the ancef.

This was a short case (45 min) and magically once we woke the patient up his BP was in the 130's systolic and he was totally fine.

My question is how often do you run across these patients that get profoundly hypotensive and only respond to epinephrine? Is this somewhat common?
 

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Was he on an ACE?


Although looking at it closer, a MAP in the 50s isn't too abnormal after general anesthesia. The non-responsiveness to pressers is though.
 

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Is his HTN poorly controlled? What HTN meds? Does the guy take an ace/arb? How much does he weigh? What gas were you using? How much fluid did you give? Did he respond to tburg? Was the cuff checked to make sure it was ok after draping? Exactly how much neo/ephed/norepi was given? Why no vaso? Any talk of popping in a-line / TEE/TTE'ing him?

I find it strange that he would respond to 1mcg of epi but not 8-16mcg of norepi, but need more details first.
 
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anbuitachi

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Is 110 SBP or MAP? You mentioned MAP of 50, so i assume 110 is MAP. Like your attending said, could be anaphylaxis or anaphylactoid to one of the medications you gave. Any other things like rash, edema, increased airway pressures, etc.
Also like above, Arb/Ace inhibitors may do it. I'm leaning more toward anaphylaxis related reaction just cause it seem like it only responded to epinephrine, not even norepi. But 1 mcg of epi intermittently is a pretty low dose

And what happened when his BP dropped from MAP 110 to 50? Did he become tachycardic? is the surgeon sitting on the carotid sinuses?
 

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If the patient is being treated with steroids for his B-cell lymphoma, that could be the reason for the hypotension. If not, your attending could be right that it's from the abx. I've seen that happen before. Either way, you did the right thing. When in a situation like this, go with Epinephrine. God's pressor.
 
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anbuitachi

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If the patient is being treated with steroids for his B-cell lymphoma, that could be the reason for the hypotension. If not, your attending could be right that it's from the abx. I've seen that happen before. Either way, you did the right thing. When in a situation like this, go with Epinephrine. God's pressor.
I can see why epi may work bit better, but why would nor epi not work even if its steroid related
 

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I can see why epi may work bit better, but why would nor epi not work even if its steroid related
I dunno maybe he gave it 1 mcg at a time lol
 
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NOsaintsfan

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More info, sorry for not being clear from the onset.

Patients BP pre surgery normally runs in the 130-140's systolic. He takes lisinopril 10mg daily and he did have this on the day of surgery.
When I referred to his BP in the 110's in my original post I was referring to his MAP.
He received a total of 2.8L of plasmalyte during the case (I know it's alot).
 

anbuitachi

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More info, sorry for not being clear from the onset.

Patients BP pre surgery normally runs in the 130-140's systolic. He takes lisinopril 10mg daily and he did have this on the day of surgery.
When I referred to his BP in the 110's in my original post I was referring to his MAP.
He received a total of 2.8L of plasmalyte during the case (I know it's alot).
he was sent into acute decompensated heart failure w massive boluses of fluid so thats why epi helped more than others. by the end of the surgery, he urinated it all out :)
 
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More info, sorry for not being clear from the onset.

Patients BP pre surgery normally runs in the 130-140's systolic. He takes lisinopril 10mg daily and he did have this on the day of surgery.
When I referred to his BP in the 110's in my original post I was referring to his MAP.
He received a total of 2.8L of plasmalyte during the case (I know it's alot).
Common things being common, I'm putting my money on ACE-induced hypotension. Look it up -- you will see it commonly in hypertensive patients on ACEi's and ARBs. Usually 1-2 units of IV vasopressin will resolve the hypotension and make it such that your boluses of phenylephrine or your pressor of choice will work afterwards. You may have to redose the vasopressin after some time has elapsed. Usually in a patient on an ACEi, if their BP tanks and they don't respond at all to 100-200 mcg of phenylephrine, I go straight for the vasopressin.
 
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NOsaintsfan

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he was sent into acute decompensated heart failure w massive boluses of fluid so thats why epi helped more than others. by the end of the surgery, he urinated it all out :)
Yea I realize that's a ton a fluid for that duration of a case. It was the type of thing where we opened up the fluids once he became hypotensive and didn't respond to phynlephrine or ephedrine. It certainly isn't the norm here to give so much fluid.
 

anbuitachi

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Yea I realize that's a ton a fluid for that duration of a case. It was the type of thing where we opened up the fluids once he became hypotensive and didn't respond to phynlephrine or ephedrine. It certainly isn't the norm here to give so much fluid.
how much levo did you give?
 
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NOsaintsfan

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Common things being common, I'm putting my money on ACE-induced hypotension. Look it up -- you will see it commonly in hypertensive patients on ACEi's and ARBs. Usually 1-2 units of IV vasopressin will resolve the hypotension and make it such that your boluses of phenylephrine or your pressor of choice will work afterwards. You may have to redose the vasopressin after some time has elapsed. Usually in a patient on an ACEi, if their BP tanks and they don't respond at all to 100-200 mcg of phenylephrine, I go straight for the vasopressin.
Thanks for the reply, I knew acei/arbs can cause refractory hypotension but had no idea it could be this profound
 

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Thanks for the reply, I knew acei/arbs can cause refractory hypotension but had no idea it could be this profound
Just for your learning benefit, there are essentially 3 systems which contribute to vasomotor tone (well, 4 if you include hormonal but that's a different discussion): sympathetic, RAAS, and vasopressinergic. Volatiles + opiate, especially in the 1 Mac range, are exceptional at blunting sympathetic stimulation. Most pts are able to compensate for this due to up regulation in RAAS and vasopressin, however if you have an anesthetized pt on an ace, RAAS is knocked out and there may not be enough endogenous vasopressin to compensate, ergo vasoplegic shock ensues. Giving exogenous vasopressin (and in some reports methylene blue) is very effective at correcting this.

In some cases, pts with hypertension may be dry the morning of induction, especially if they're poorly controlled and on chronic lasix ace hctz, but once you've rapidly bolused 1-1.5L (or better yet have had the circulator do a passive leg raise) with no response, take it easy on the fluid because you're likely dealing with a tone problem, not a volume problem.
 
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NOsaintsfan

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Just for your learning benefit, there are essentially 3 systems which contribute to vasomotor tone (well, 4 if you include hormonal but that's a different discussion): sympathetic, RAAS, and vasopressinergic. Volatiles + opiate, especially in the 1 Mac range, are exceptional at blunting sympathetic stimulation. Most pts are able to compensate for this due to up regulation in RAAS and vasopressin, however if you have an anesthetized pt on an ace, RAAS is knocked out and there may not be enough endogenous vasopressin to compensate, ergo vasoplegic shock ensues. Giving exogenous vasopressin (and in some reports methylene blue) is very effective at correcting this.

In some cases, pts with hypertension may be dry the morning of induction, especially if they're poorly controlled and on chronic lasix ace hctz, but once you've rapidly bolused 1-1.5L (or better yet have had the circulator do a passive leg raise) with no response, take it easy on the fluid because you're likely dealing with a tone problem, not a volume problem.
Thank you, the learning points are appreciated.

In addition thanks to all the constructive posts above.
 

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I'm missing the part about why the attending didn't consider the lisinopril on the day of surgery to have a part in this...zebras being what they are I might have said the same thing about the possibility of a reaction to the abx...unless I knew about the ACEI
 

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Is there a reason anesthesiologist use ephedrine and phenylephrine during surgery. In the ICU we tend to dislike phenylephine and prefer levophed. Just for my education. It seems levophed is hard to get immediately as seems like pharmacy has to mix.
 
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I'm missing the part about why the attending didn't consider the lisinopril on the day of surgery to have a part in this...zebras being what they are I might have said the same thing about the possibility of a reaction to the abx...unless I knew about the ACEI
Not sure of the answer to this.

My attending for this case is a guy who did fellowships in CC and CV. He generally covers the heart room and the ICU. I was actually super surprised he was covering this room that day. He was assigned the room the morning of surgery and was a last minute switch with another attending. I discussed the cases for that day with a different attending the day prior only to find out my staff had changed the next morning.

All that is to say maybe it's a detail he overlooked, I don't know.

No matter I certainly learned from that case and will better because of it going forward.
 

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I kind of figured it may have to do with availability. I have asked our pharmacy to keep levophed in the Pyxis but apparently it can't stay in storage for a while.
It is more than that, though. Extravasated phenylephrine or ephedrine from a peripheral IV have minimal effect with regard to tissue damage--this is why they are used routinely in day-to-day anesthesia practice for stable patients. Googling extravasated norepinephrine or epinephrine will show you what comes to our minds when we are forced to use these medications peripherally.
 
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fakin' the funk

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New CA1 here had a case the other day that still has me wondering what happened.
MAP of 50 is not that low. 80/40? 70/30? That's what a lot of patients's BP "wants to be" under a full MAC of anesthesia.

Presumably you also just washed in a ton of volatile; it takes time to wash out. You also just gave fentanyl. This sounds like a small procedure with minimal stimulation, so you're most likely being heavy-handed. Hypotension is the price you pay for guaranteeing no pt movement w/o NMB on board.

0.8MAC vs 1.1 MAC is 30% less gas but that doesn't give you 30% higher MAP, that's not how it works.

Unusual to have no response to the 2 first-line pressors. But, you're a CA-1, and I dunno if you're giving 100mcg neo to a 120kg guy or giving 5mg ephedrine (neither of these two examples would be expected to do much).
 
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MAP of 50 is not that low. 80/40? 70/30? That's what a lot of patients's BP "wants to be" under a full MAC of anesthesia.

Presumably you also just washed in a ton of volatile; it takes time to wash out. You also just gave fentanyl. This sounds like a small procedure with minimal stimulation, so you're most likely being heavy-handed. Hypotension is the price you pay for guaranteeing no pt movement w/o NMB on board.

0.8MAC vs 1.1 MAC is 30% less gas but that doesn't give you 30% higher MAP, that's not how it works.

Unusual to have no response to the 2 first-line pressors. But, you're a CA-1, and I dunno if you're giving 100mcg neo to a 120kg guy or giving 5mg ephedrine (neither of these two examples would be expected to do much).
Hi, thanks for the reply. The reason I initially became concerned is because the MAP was in the high 40's (45-48) and was difficult to just get into the 50's. Initially I gave a few doses of 100mcg of neo and 5mg of ephedrine, that quickly progressed to 400mcg doses of neo and 15mg doses of ephedrine with no effect. This was when I called my attending who was present for the rest of the case.

To be sure their is plenty I have yet to learn and this case is a good example of that. The fully their was no adverse outcome to the patient and the surgery was overall a success. I appreciate everyone's constructive input.
 

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More info, sorry for not being clear from the onset.

Patients BP pre surgery normally runs in the 130-140's systolic. He takes lisinopril 10mg daily and he did have this on the day of surgery.
When I referred to his BP in the 110's in my original post I was referring to his MAP.
He received a total of 2.8L of plasmalyte during the case (I know it's alot).
The reaction can be quite profound. One thing to note that lisinopril is a once daily medication, so it can be important to note when they take their meds. If they take it every night at 10-11pm, they technically will not have taken it day of surgery, but it'll still be around in their system for a first case start.
 

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I concur that this was most likely the morning lisinopril. Best treatment for that is vaso (but levo or any other strong pressor or tons of phenylephrine will work, too).

And MAP of 40-50 is not OK, ever, except for patients who live at that MAP at baseline (definitely not the hypertensive kind). There are studies that show that even brief episodes of hypotension can cause damage to organs (i.e. worsen outcomes), especially the kidneys. It drives me crazy when I see people just shrugging their shoulders when the SBP 140 person is in the 80's for 15 minutes, or when they are happy with a MAP of 65 when the patient obviously doesn't live there.

Another thing: most studies show that pressors are better than fluids, both intraop and in the ICU. Unless you are sure that you have hypovolemia and/or ongoing fluid losses (the one from an open abdomen or other large surgical field is actually minimal), give pressors. And don't chase urine output, especially in laparoscopic or prone cases (or any other case where there may be iatrogenic intraabdominal hypertension). Hypervolemia is almost as bad as hypo-.
 
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I find it strange that he would respond to 1mcg of epi but not 8-16mcg of norepi, but need more details first.
I don't. For reasons unknown to me, some people respond much better to epi than norepi. That's why some authors advise to check the response to both in the beginning, or at least try epi as the second pressor, especially in patients who need high doses of norepi.

Epi has gotten a bad rap because it produces tachycardia and arrhythmias, and hence worsens outcomes, but it's not the drug's fault, it's the morons' who don't know how to use it (and overdose it). Kind of what happened to the Swan. Levo is the go-to drug mostly because it is the safest strong pressor in the hands of the ignorant (not that it's not a great one), hence patients have better outcomes (even) when cared for by amateurs.

P.S. I used strong words because guns and cardiovascular drugs should not be played with.
 
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Hypotension is the price you pay for guaranteeing no pt movement w/o NMB on board.
I am afraid hypotension is the price the patient pays for having a bad/lazy anesthesia provider.
 
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nimbus

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I concur that this was most likely the morning lisinopril. Best treatment for that is vaso (but levo or any other strong pressor or tons of phenylephrine will work, too).

And MAP of 40-50 is not OK, ever, except for patients who live at that MAP at baseline (definitely not the hypertensive kind). There are studies that show that even brief episodes of hypotension can cause damage to organs (i.e. worsen outcomes), especially the kidneys. It drives me crazy when I see people just shrugging their shoulders when the SBP 140 person is in the 80's for 15 minutes, or when they are happy with a MAP of 65 when the patient obviously doesn't live there.

Another thing: most studies show that pressors are better than fluids, both intraop and in the ICU. Unless you are sure that you have hypovolemia and/or ongoing fluid losses (the one from an open abdomen or other large surgical field is actually minimal), give pressors. And don't chase urine output, especially in laparoscopic or prone cases (or any other case where there may be iatrogenic intraabdominal hypertension). Hypervolemia is almost as bad as hypo-.

What is your target BP for a pt with a baseline BP of 140/90 in preop? What do you use to treat low BP? Just curious. I must say I am guilty of being happy with a MAP of 65 in most of my patients.

And do you have the references that show short periods of hypotension worsen outcome? In what populations?

This patient's initial BP was 120/75. I did not treat it. I would not treat it even if the initial systolic was 140. I consider the vitals shown to be essentially perfect intraoperative vital signs.

IMG_3694.JPG
 
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nimbus

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I have attached some recent info on intraoperative hypotension. They are stressing this at my program
Thank you.


There is no dispute there is an association between intraoperative hypotension and postop complications. But sicker, higher risk patients tend to have more intraoperative hypotension. That does not prove causation. The review itself says

"Unfortunately, the scientific literature is essentially silent regarding the consequences of treating intraoperative hypotension with inotropes or vasopressors."

What we need is a prospective study comparing different BP management strategies. That has not been done.
 
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What is your target BP for a pt with a baseline BP of 140/90 in preop? What do you use? Just curious. I must say I am guilty of being happy with a MAP of 65 in most of my patients.

And do you have the references that show short periods of hypotension worsen outcome? In what populations?

This patient's initial BP was 120/75. I'm not treating it.

View attachment 222089
These are legit questions. I will answer them from memory, but I'll try to find the references for you.

Most of the studies I have read were done in ICU populations, especially people in septic shock. That's where that MAP of 65 comes from. However, that doesn't mean the numbers are not valid for the OR population, especially if unhealthy. A cursory Google search will bring up a number of Anesthesiology (journal) papers about the same subject, quoting about the same numbers and concerns. This seems to be a good presentation about the subject: https://aaaa.memberclicks.net/assets/hypotension and anesthesia outcomes.pdf. Also the article @NOsaintsfan posted.

I'll try to summarize what I know:

- There is proof that a MAP of less than 60 worsens outcomes (produces ischemia in various internal organs) in most patients. Hence the number 65.
- In ICU patients, the difference between a MAP of 65-70 and a MAP of 75-80 is not much, except for kidney injuries. The kidney is very sensitive to hypotension, more than the brain.
- In the ICU (and no reason to believe that other populations are much different), AKI correlates with decrease in survival. This is essential. Hence hypotension correlates with decrease in survival.
- For chronically hypertensive patients those numbers tend to be higher (right shift of the autoregulation curves).
- For that reason, most anesthesiology books will recommend maintaining the BP within 20-25% of the baseline, but ideally as close to it as possible (especially if the patient is not healthy).

To me, baseline is the patient's BP at rest, unstressed. So the preop BP is probably at least slightly higher than baseline. One may judge by how much by talking to the patient; anxiety can raise MAP by 25+% easily. Also, sometimes, hypertensive patients can tell their usual values, the same way a disciplined diabetic knows his usual blood sugar.

If I have a patient with BP of 140/90 preop, it depends a lot on the patient where my target BP will be. If the patient is known to be hypertensive, has taken his BP pills, and he's relaxed, that's probably my baseline. For that patient, I will definitely get antsy at a SBP under 100-110. If the patient is not known as hypertensive, I will assume he's just nervous, so I will inquire about the anxiety level and go from there. I also give a small dose of midazolam (2 mg) for most of my intubations, and the post-midaz values may be more reliable than the ones from the preop area. Another set of useful numbers are the ones from the preop clearance; most patients will be way more relaxed when talking to their PCP in a familiar non-threatening environment.

Essentially, my rule is not to drop the BP by more than 20-25% when compared to the baseline, and to keep it as close to the baseline as possible, especially if normally low. That means maintaining anesthesia on the lighter side (which also speeds up emergence) or giving pressors (there is light anesthesia and then there is recall-level "anesthesia"). The sicker the patient, the tighter my target BP interval. And, of course, I care much less for an outpatient MAC case than for a high-risk GA. It's a lot of judgment call but, in the case of a bad outcome, laymen will judge you based on some stupid rule from a book.

Btw, I absolutely would not treat that BP either. But an SBP under 85-90 would get my attention.
 
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anbuitachi

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I see a lot of people using the first BP in OR prior to any anesthesia as 'baseline', then they keep it within 25% of that, which i think doesn't make sense for many since most people get nervous and their pressure skyrockets. It's hard to tell what their baseline pressure is when all they got in their chart is 1 preop bp, even that may be elevated compared to baseline. Had good # of patients come in for simple cases like ovarian cyst , otherwise healthy 30 yr olds, and their pressure is SBP 220.

And I figure ICU BP is not hte same as many OR BPs. You are in the ICU for a reason, probably sick as hell, and half dead already. You aren't under general anesthesia, and general anesthesia lowers metabolic activity, decreasing O2 requirement overall esp w paralytic
 

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I know. But I consider this kind of stuff a quality issue that separates us from CRNAs.

The reason many floor people will literally freak out from 85/55 in a non-healthy patient is because they rarely see it. Just because we see it more frequently (and we get away with doing nothing) doesn't mean we should get complacent with it. Absence of evidence (of bad outcomes) is not evidence of absence. That's all I am saying. We are doctors.

On the other hand, I have kept patients at 80/40 under GA for an hour, without a blink. But the patients' preop BP was close to that (young healthy females).
 
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anbuitachi

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Is there a reason anesthesiologist use ephedrine and phenylephrine during surgery. In the ICU we tend to dislike phenylephine and prefer levophed. Just for my education. It seems levophed is hard to get immediately as seems like pharmacy has to mix.
A lot more available. Pharmacy would have to make up individual norepi sticks for us. Our vials of NE come in 4mg, which is too much for almost every case. Our phenylephrine sticks come in 100mcg/ml 10 ml sticks. Im guessing phenylephrine ends up being cheaper too.

Also phenylephrine serves its purpose very well. Works well for everybody except some cardiac patients, then they may get a central line. Can be given thru peripheral IV w no issues, can run infusion thru peripheral IV. Otherwise we'd have to put central line in everybody who may need a pressor infusion. The OR isn't like the ICU which is usually well staffed and not under pressure to keep things moving.
 
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I see a lot of people using the first BP in OR prior to any anesthesia as 'baseline', then they keep it within 25% of that, which i think doesn't make sense for many since most people get nervous and their pressure skyrockets. It's hard to tell what their baseline pressure is when all they got in their chart is 1 preop bp, even that may be elevated compared to baseline. Had good # of patients come in for simple cases like ovarian cyst , otherwise healthy 30 yr olds, and their pressure is SBP 220.

And I figure ICU BP is not hte same as many OR BPs. You are in the ICU for a reason, probably sick as hell, and half dead already. You aren't under general anesthesia, and general anesthesia lowers metabolic activity, decreasing O2 requirement overall esp w paralytic
General anesthesia doesn't significantly lower metabolic activity (when compared to baseline). Hypothermia does. Otherwise one wouldn't need the latter for brain protection, especially in the presence of the former. ;)

Also, don't judge the body by the brain. As I mentioned, the kidney likes hypotension much less than the brain (as far as we can measure the outcomes). While the cortex may be turned off, there is still an ongoing stress (response) in the body.

Shivering and fasciculations can indeed increase oxygen consumption. But that's not the baseline, so muscle relaxants do not decrease metabolic requirements that much (when compared to the baseline resting patient).
 
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Is 110 SBP or MAP? You mentioned MAP of 50, so i assume 110 is MAP. Like your attending said, could be anaphylaxis or anaphylactoid to one of the medications you gave. Any other things like rash, edema, increased airway pressures, etc.
Also like above, Arb/Ace inhibitors may do it. I'm leaning more toward anaphylaxis related reaction just cause it seem like it only responded to epinephrine, not even norepi. But 1 mcg of epi intermittently is a pretty low dose

And what happened when his BP dropped from MAP 110 to 50? Did he become tachycardic? is the surgeon sitting on the carotid sinuses?
If the surgeon was sitting on the carotids, the BP would have recovered much more easily. Plus such a drop in MAP requires a lot of carotid pressure, and it's impossible to miss the bradycardia.

If the patient had anaphylaxis, I would assume they would have noticed something else, such as increased airway pressures/wheezing from bronchospasm, rash, swelling. Plus anaphylaxis doesn't get better suddenly when the patient wakes up. Plus it doesn't get better from just 1 mcg of epi (more like 100+).

This was the lisinopril, until proven otherwise.
 
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NOsaintsfan

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If the surgeon was sitting on the carotids, the BP would have recovered much more easily. Plus such a drop in MAP requires a lot of carotid pressure, and it's impossible to miss the bradycardia.

If the patient had anaphylaxis, I would assume they would have noticed something else, such as increased airway pressures/wheezing from bronchospasm, rash, swelling. Plus anaphylaxis doesn't get better suddenly when the patient wakes up. Plus it doesn't get better from just 1 mcg of epi (more like 100+).

This was the lisinopril, until proven otherwise.
Agree with this. Although we didn't give any vasopressin my suspecision is it was the lisinopril. I have no other explanation that makes sense.

The surgeon was aware of the hypotension and actually halted surgical activity for several minutes with no appreciable difference in BP. The patient wasnt tachycardic, in fact his heart rate was in the 60-70 range in between epi doses. No change in peak or plateau pressures. We examined the patients skin and even log rolled him to verify absence of rash.
 

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Epi has gotten a bad rap because it produces tachycardia and arrhythmias, and hence worsens outcomes, but it's not the drug's fault, it's the morons' who don't know how to use it (and overdose it).
Agree. Very occasionally I use small doses of epi as a first-line pressor. When dosed judiciously, the tachycardia and associated problems can be minimized.
 

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If the surgeon was sitting on the carotids, the BP would have recovered much more easily. Plus such a drop in MAP requires a lot of carotid pressure, and it's impossible to miss the bradycardia.

If the patient had anaphylaxis, I would assume they would have noticed something else, such as increased airway pressures/wheezing from bronchospasm, rash, swelling. Plus anaphylaxis doesn't get better suddenly when the patient wakes up. Plus it doesn't get better from just 1 mcg of epi (more like 100+).

This was the lisinopril, until proven otherwise.
It's just odd 10 mg of lisinopril made hte patient unresponsive to 8-16 mcg norepi pushes yet respond to 1 mcg of epi. The receptors are not that different between epi and norepi
 

Ezekiel2517

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It's just odd 10 mg of lisinopril made hte patient unresponsive to 8-16 mcg norepi pushes yet respond to 1 mcg of epi. The receptors are not that different between epi and norepi
That's bc it's not bc of the ACEI.
 

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Is there a reason anesthesiologist use ephedrine and phenylephrine during surgery. In the ICU we tend to dislike phenylephine and prefer levophed. Just for my education. It seems levophed is hard to get immediately as seems like pharmacy has to mix.
Broadly speaking, the etiology of the hypotension we see in the OR is different than what you see in the ICU. In the OR, most hypotension is caused by our anesthetic agents (induction agents, volatile anesthetics, spinal/epidural anesthesia), which mostly cause hypotension by reducing SVR. A pure alpha agonist like phenylephrine is a logical choice.

I'm not especially fond of ephedrine; it's underwhelming and unreliable. And some places consider it a controlled substance and the accounting is a nuisance.
 

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good read.
how do people decide what is a low dose and what isnt? they claim .1mcg/kg/min is low dose. thats 100ng /kg/min, in a 100kg man is 10mcg/min. is that low dose? sounds like medium dose to me
.1 mcg/kg/min (of levo, I guess) is about 7 mcg/min for the average 70 kg person, which is low dose.
 
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