Cardiac Risks from anesthesia

[SilverStreak]

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This is probably a simple question to most of you, so bear with me since I'm learning. I've reviewed the preop anesthesia checksheet at work, I understand the ASA classification of risk based on the patients medical history and current medical condition. I also know that there is an increased risk for stroke and heart complications with anesthesia. What I can't pinpoint is exactly why anesthesia can cause or contribute to these events. Is it the effect anesthetics have on the body, the stress of the surgery itself, or something else I'm missing? I also realize the pathology of the surgery, length of the surgery, plan of anesthetic all have an effect to some degree on patients risk from anesthesia.

 

[militarymd]

This is probably a simple question to most of you, so bear with me since I'm learning. I've reviewed the preop anesthesia checksheet at work, I understand the ASA classification of risk based on the patients medical history and current medical condition. I also know that there is an increased risk for stroke and heart complications with anesthesia. What I can't pinpoint is exactly why anesthesia can cause or contribute to these events. Is it the effect anesthetics have on the body, the stress of the surgery itself, or something else I'm missing? I also realize the pathology of the surgery, length of the surgery, plan of anesthetic all have an effect to some degree on patients risk from anesthesia.

It's not the anesthesia...it's the surgery.

 

[WalterSobchak]

I don't believe there is an increased risk of stroke with anesthesia. The problem with cardiac issues arises when a patient with certain conditions is exposed to certain anesthesics. Basically your heart requires a certain amount of oxygen. Some anesthesics change the balance of what your heart receives by direct myocardial depression, a decrease in afterload (decreased systemic vascular resistance), or a decrease in preload (blood coming back to the heart). If a person has a condition which allows them to live comfortably with minimal effort, a change in one of these conditions will push them over the edge. Even the myoclonus associated with 1/4 to 1/3 of patients receiving etomidate can do this. Generally, these conditions can be avoided by careful consideration, but sometimes not. After these points, the stress of surgery on the heart can do the same thing. I hope this helps.

 

[militarymd]

I don't believe there is an increased risk of stroke with anesthesia. The problem with cardiac issues arises when a patient with certain conditions is exposed to certain anesthesics. Basically your heart requires a certain amount of oxygen. Some anesthesics change the balance of what your heart receives by direct myocardial depression, a decrease in afterload (decreased systemic vascular resistance), or a decrease in preload (blood coming back to the heart). If a person has a condition which allows them to live comfortably with minimal effort, a change in one of these conditions will push them over the edge. Even the myoclonus associated with 1/4 to 1/3 of patients receiving etomidate can do this. Generally, these conditions can be avoided by careful consideration, but sometimes not. After these points, the stress of surgery on the heart can do the same thing. I hope this helps.

That's quite a load of you know what.

 

[SilverStreak]

I don't believe there is an increased risk of stroke with anesthesia. The problem with cardiac issues arises when a patient with certain conditions is exposed to certain anesthesics. Basically your heart requires a certain amount of oxygen. Some anesthesics change the balance of what your heart receives by direct myocardial depression, a decrease in afterload (decreased systemic vascular resistance), or a decrease in preload (blood coming back to the heart). If a person has a condition which allows them to live comfortably with minimal effort, a change in one of these conditions will push them over the edge. Even the myoclonus associated with 1/4 to 1/3 of patients receiving etomidate can do this. Generally, these conditions can be avoided by careful consideration, but sometimes not. After these points, the stress of surgery on the heart can do the same thing. I hope this helps.

These effects should be minimal though...if you're giving fluids to take care of preload, titrating vasoactive gtts to help keep afterload in the normal range and perfusing organs, and giving enough o2 during the procedure by ventilating the patient, right? I can understand your explanation in light of a CHFer with an EF 30%, their heart is already compromised and can't take any more stress and continue to work, but what about your healthy pt with your standard surgery, say a lap chole, if a cardiac clearance is ordered, why is this usually done? I only ask because recently I've had a good number of patients who came in for something else and when they got the cardiac workup, the ended up in the cath lab and having a bypass done before they could proceed with whatever other medical/surgical interventions needed to be done. Most of the time these patients were asymptomatic or what we would call atypical cardiac symptoms and they didn't affect their lifestyle much, so they didn't think it was that big a deal.

I just didn't know if the cardiac clearance bit it a CYA for the surgeon. Too often I hear patients told the risks of anesthesia specifically including stroke, and heart attack. It just seems to me that there has to be plenty of other things that set these patients up for these besides just anesthesia. I have read about some of the anesthetics being linked to things like cardiac steal and didn't know if this was where the link between anesthesia and cardiac events occur.

How often would you estimate an intraop MI occuring Mil, Noyac, and when it does, is anesthesia the contributing factor from the surgeons standpoint? I can't see too many surgeons telling the family their surgery is what did it. I've seen anesthesia be "blamed" so to speak for lack of a better word for some outrageous things in my oppinion, but I figured maybe I'm missing something.

 

[militarymd]

OK, let me spell it out. When I said the above post is a load of you know what....I meant crap.


Volatile anesthetics has ischemic preconditioning properties...meaning exposure of these drugs to the myocardium protects it.

All volatile anesthetics are myocardial depressants....so let me ask you this...why is a depressant stressful for the heart? Well....IT IS NOT...depressing the heart, decreasing oxygen consumption....IS A GOOD THING.

Ahhhh, next comes the MUCH talked about, but NEVER (rare enough to say NEVER) seen phenomenon of myocardial failure in the setting of low EF and volatile anesthetic exposure.....HUGE load of you know what...

When are they going to STOP teaching this dribble?

Under anesthesia, total oxygen consumption goes down....total cardiac output requirements goes down.....therefore a slightly decreased cardiac output as a result of myocardial depressant effects are NO BIG DEAL.

Now, in patients with high sympathetic tone (CHF states) or bad vascular disease, there may be significant hypotension related to volatile anesthetics....but that's what phenylephrine is for....ask any cardiac anesthesiologist.

Prolonged hypotension will lead to hypoperfusion of the LV and lead to subsequent ischemia, but you treat the hypotension.

In the perioperative period, the stress response (adh, renin, cortisol, fibrinogen, tf, and other factors) cause unstable coronary thrombi formation...leading to MIs.....and that stress response is secondary to surgery...NOT anesthesia.

Read the ACC practice guidelines for preoperative evalulation....risk is related to the type of surgery (high, intermediate, low) risk....NOT the type of anesthesia.

Ultimately, it is hard to tease out the difference, because you rarely will have one without the other, but the fact that a regional anesthestic with no expsure to volatile anesthetic agents does not protect you from having an MI should tell you something.

 

[SilverStreak]

OK, let me spell it out. When I said the above post is a load of you know what....I meant crap.


Volatile anesthetics has ischemic preconditioning properties...meaning exposure of these drugs to the myocardium protects it.

All volatile anesthetics are myocardial depressants....so let me ask you this...why is a depressant stressful for the heart? Well....IT IS NOT...depressing the heart, decreasing oxygen consumption....IS A GOOD THING.

Ahhhh, next comes the MUCH talked about, but NEVER (rare enough to say NEVER) seen phenomenon of myocardial failure in the setting of low EF and volatile anesthetic exposure.....HUGE load of you know what...

When are they going to STOP teaching this dribble?

Under anesthesia, total oxygen consumption goes down....total cardiac output requirements goes down.....therefore a slightly decreased cardiac output as a result of myocardial depressant effects are NO BIG DEAL.

Now, in patients with high sympathetic tone (CHF states) or bad vascular disease, there may be significant hypotension related to volatile anesthetics....but that's what phenylephrine is for....ask any cardiac anesthesiologist.

Prolonged hypotension will lead to hypoperfusion of the LV and lead to subsequent ischemia, but you treat the hypotension.

In the perioperative period, the stress response (adh, renin, cortisol, fibrinogen, tf, and other factors) cause unstable coronary thrombi formation...leading to MIs.....and that stress response is secondary to surgery...NOT anesthesia.

Read the ACC practice guidelines for preoperative evalulation....risk is related to the type of surgery (high, intermediate, low) risk....NOT the type of anesthesia.

Ultimately, it is hard to tease out the difference, because you rarely will have one without the other, but the fact that a regional anesthestic with no expsure to volatile anesthetic agents does not protect you from having an MI should tell you something.

Thanks Mil. Remember, I'm learning on my own right now, so I take what I hear and see to try and search explanations for myself. I still don't always know yet what's true and what's not. Great explanation and makes perfect sense.

 

[Mman]

I just didn't know if the cardiac clearance bit it a CYA for the surgeon. Too often I hear patients told the risks of anesthesia specifically including stroke, and heart attack.

When used properly, a cardiology consult prior to a surgical procedure should be to ask the cardiologist for assistance in optimizing their cardiac health. Are they on the right medications? Would a stress test change management? etc. Unfortunately, many times a surgeon will just send a patient to cardiology for "clearance" which is nuts. An attending I worked with one time told me that he didn't need "clearance" from anybody because if their heart was pumping before surgery he could keep it pumping during virtually any operation.

As for people being told the risks, this is simply a medico-legal issue. If you have any procedure done in the hospital, you will be told the risks of any possible outcome including death. It's always easier to defend yourself in a lawsuit if the patient signed a piece of paper with their unintended outcome listed as a possibility.

 

[Noyac]

. It's always easier to defend yourself in a lawsuit if the patient signed a piece of paper with their unintended outcome listed as a possibility.

No its not!

PS: For anyone that believes Mil's response is inaccurate, answer this. Why is the risk of MI,CVA,etc greater in the 3-5 days post-op?

 

[Mman]

No its not!

Easier, not easy.

 

[Noyac]

Easier, not easy.

A medical malpractice case requires a few things b/4 its a case. 1) a duty must exist. Once you have them sign a consent, you have a duty. 2) There must be a breach of duty. 3) The breach of duty must be the actual cause of the adverse outcome. 4) And ascertainable damages must have occured. "Harm".
In a malpractice case you are held against the standards of your profession. In my opinion, if you get a consent you are not protected, whatsoever. The consent is what declares your duty. If you don't consent them you are outside of the standard of care, that's all. Pts must be informed of the risks but just because you informed them doesn't mean you are not held accountable if those risks do occur. Therefore, in my opinion again, consent does not protect you, whatsoever. If you don't consent however, then you are screwed.
Mman, I know you were just making a general statement. But I took this oportunity to clarify to others that a consent is not protective in any way. It just gets you started in the whole legal arena, "duty".

 

[proman]

Informed consent protects you against the criminal act of battery. It does nothing to protect you against the civil act of alledged malpractice.

 

[KluverBucy]

A medical malpractice case requires a few things b/4 its a case. 1) a duty must exist. Once you have them sign a consent, you have a duty. 2) There must be a breach of duty. 3) The breach of duty must be the actual cause of the adverse outcome. 4) And ascertainable damages must have occured. "Harm".
In a malpractice case you are held against the standards of your profession. In my opinion, if you get a consent you are not protected, whatsoever. The consent is what declares your duty. If you don't consent them you are outside of the standard of care, that's all. Pts must be informed of the risks but just because you informed them doesn't mean you are not held accountable if those risks do occur. Therefore, in my opinion again, consent does not protect you, whatsoever. If you don't consent however, then you are screwed.
Mman, I know you were just making a general statement. But I took this oportunity to clarify to others that a consent is not protective in any way. It just gets you started in the whole legal arena, "duty".

Ah yes...the points that constitute medical malpractice.
1) Duty
2) Breach of Duty
3) Causation
4) Damages

and with regard to the consent protecting your a$$, well not quite. otherwise i'd just tell every patient to sign a piece of paper that it's possible something bad will happen and then i would never have to worry about a suit.