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Levo and pH

Posted

Specializes in ICU, Postpartum, Onc, PACU. Has 9 years experience.

we had the most awful night last night starting at the beginning of the shift (1945). got a "code blue to c-section #2" page overhead so the sc and myself (the float/resource nurse) ran there and they're doing compressions on a lady who's not even closed up from her c-s yet! baby was good, but the mom ended up coming to us and it was basically an all night medical code with another official "code blue" called on her at around 0200. first time i've cried on the way home from work :crying2:

anyways, my question was about the levo not working for her bp. her ph was in the 7.2 range on the first abg and she got an amp of hco3. then on the next abg (maybe an hour later) it was down to 7.19. then, since the bp was dropping so fast, the pma in the unit said to just run it wide open, but it wasn't working. the primary nurse (who's very experienced, whereas i've barely been in the icu for 2 years) said that the levo wouldn't do anything for the bp while the ph was so low. can someone explain this?

god, every night i work i seem to be overwhelmed with everything i don't know!!! :o

Chisca, RN

Specializes in Dialysis. Has 37 years experience.

Think like a cell. If your body reverts to anaerobic respiration you are producing alot of lactic acid. This causes vasodilation and the levophed cannot overcome this even with boluses of sodium bicarb. As a neurotransmitter levophed facilitates communication between nerve cells and the muscles. If the muscles that constrict the blood vessels don't receive the message they won't constrict. Without correction of the underlying cause of acidosis it is only a matter of time before death arrives.

General E. Speaking, RN, RN

Specializes in floor to ICU.

(((hugs))) sorry you had a rough shift. I had the same problem. I have been nursing for a while but moved to ICU recently so I am still learning. My pt was on Neo, Levo, Epi AND Vasopressin. SBP barely 70s. ABGs read that pH was 6.9. After the bicarb the BP came up a bit and the charge nurse said "thanks to the bicarb". I, too, questioned why. Pretty much explained what the other poster said above. He went on to explain that acidosis also decreases the body's response to catecholamines.

CRIMSON

Specializes in Cardiac, Derm, OB.

PH and volume both sound as though they may have been a contributing factor. If there is no volume, you can squeeze the Levo all you want but it will not help if there is nothing there. (Csection loss of fluids and blood)

A bicarb drip may have been a better option than just bolus'.

A bicarb drip may have been a better option than just bolus'.

Or THAM gtt! :yeah:

Maevish, ASN, RN

Specializes in ICU, Postpartum, Onc, PACU. Has 9 years experience.

Thanks for the explanations! One thing though, I went to an amazing, all-day cardiac class and learned a ton. The only thing is, no one ever mentions the necessity of having a near-normal pH so that the levo (or whatever) does its job. Is this something that everyone assumes we know?

Also, in our septic pts who are adequately hydrated and the HP is still low, we start levo and the BP goes up. And these pts have really jacked up pG levels too, so I'm confused.

I just wanna understand it! :confused:

Xoxo

RN1980

Specializes in icu/er.

having a decent ph level in order for drugs to work is not only a concern for levophed but for pretty much the rest of the presser family of drugs. like the above poster explained, if the cells are splitting open from a terrible ph there are no cells or only partailly functional poor cells to work with.

lactic acidosis is a physiological condition characterized by low ph in body tissues and blood ([color=#0645ad]acidosis) accompanied by the buildup of [color=#0645ad]lactate especially [color=#0645ad]d-lactate, and is considered a distinct form of [color=#0645ad]metabolic acidosis.[color=#0645ad][1] the condition typically occurs when cells receive too little oxygen ([color=#0645ad]hypoxia), for example during vigorous exercise. in this situation, impaired cellular respiration leads to lower ph levels. simultaneously, cells are forced to metabolize [color=#0645ad]glucose [color=#0645ad]anaerobically, which leads to lactate formation. therefore, elevated lactate is indicative of tissue [color=#0645ad]hypoxia, [color=#0645ad]hypoperfusion, and possible damage. lactic acidosis is characterized by lactate levels >5 mmol/l and serum ph

[/size][/size]

norepinephrine constriction of small terminal arterioles,

which is largely dependent on a2-receptors, was markedly

reduced by acidosis. the data suggest that

increases in local co2/h' concentration produced by

altered parenchymal tissue metabolic rate, oxygen

delivery, or blood ph may directly influence adrenergic

responsiveness of microvessels by a selective action

on a2-mediated constriction. http://circres.ahajournals.org/cgi/reprint/66/6/1643

Vasoconstriction of the smooth muscle cells on your vessels requires appropriate enzyme function. As your bloodstream is flooded with H+ (in your pt's metabolic acidosis), the enzymes deform and the "lock and key" mechanism fails. You can give all the norepi you want, but it won't work very well.

http://www.phschool.com/science/biology_place/labbench/lab2/ph.html

7.20 is severe acidosis. One amp HCO3 is a joke to that pH. As was already posted, this pt should get 2-4 amps IVP stat and a bicarb gtt. You can calculate the bicarb needed based on the pt's weight and base deficit, but in a code situation just push it in and fine tune it later.

The same principle for vascular smooth muscle also applies to cardiac contractility, so she had tone and pump failure most likely.

-TB

Absolutely, GREAT question!

As your body becomes more acidic or aklaline the proteins in your body and

the structure of different drugs, enzymes, metabolites denature and break

down. When your pH falls out of normal range in either direction the

structural shape of the molecules in your body are compromised.

Drugs that work before no longer work and are useless.

Once a molecule has an altered shape it no longer

fits in the receptor site for which it correlates.

If this is happening in your pt and you have

very low pH consistantly consider a bicarb gtt. Turn up

the rate on the vent, increase the tidal volume and try to figure out why they

are so damn acidotic. Are the kidney failing?

Sepsis? Flush out the lactate.

think of putting milk in lemon juice. It curdles right?

Thats because the acidic environment denatures

the protein in the milk.

The acidic environment is doing just that to your

body and all the other substances inside it.

Clear as mud?

cubeo

Specializes in CCU-CCRN.

PH and volume both sound as though they may have been a contributing factor. If there is no volume, you can squeeze the Levo all you want but it will not help if there is nothing there. (Csection loss of fluids and blood)

A bicarb drip may have been a better option than just bolus'.

yes, bicarb drip..and levo would clamp down all those capillaries in your extremities -> increase lactic acid build up

richard1980

Specializes in SICU/CVICU. Has 7 years experience.

If she was that sick she needed a swan... and from the sounds of it tons and tons and tons of volume. How much volume is tons? Give it on pressure bags or with a Level one rapid infuser/warmer until you get to the downward trend of the starling curve. I'm guessing her hgb was ok? Remember....always optimize volume status before using vasopressors and inotropic agents. A pH of 7.19, while very low, isn't ridiculously low and the levo should've done SOMETHING. She probably should've had about 4 amps of bicarb and a gtt or if that didn't work, (as someone already suggested) tham. What's a PMA and why would they tell you to run levo wide open without trying something else like epinephrine or neosynephrine?

If she was that sick she needed a swan... and from the sounds of it tons and tons and tons of volume. How much volume is tons? Give it on pressure bags or with a Level one rapid infuser/warmer until you get to the downward trend of the starling curve. I'm guessing her hgb was ok? Remember....always optimize volume status before using vasopressors and inotropic agents. A pH of 7.19, while very low, isn't ridiculously low and the levo should've done SOMETHING. She probably should've had about 4 amps of bicarb and a gtt or if that didn't work, (as someone already suggested) tham. What's a PMA and why would they tell you to run levo wide open without trying something else like epinephrine or neosynephrine?

We don't know alot about the pt but I don't think a swan is going to help in this situation based on the info provided. 7.19 isn't "ridiculously low" but is more than low enough to cause refractory depression of vascular tone and myocardial function.

Fix her acid-base first then look for other problems.

Norepi is actually a great drug in this case as it gives you more potent combined beta and alpha effects. The pt's LV function is probably at least moderate to severely impaired at that pH. Pure phenylephrine is only adding afterload. Epi is similar to norepi but nowhere near as strong for a situation like this.

richard1980

Specializes in SICU/CVICU. Has 7 years experience.

We don't know alot about the pt but I don't think a swan is going to help in this situation based on the info provided. 7.19 isn't "ridiculously low" but is more than low enough to cause refractory depression of vascular tone and myocardial function.

Fix her acid-base first then look for other problems.

Norepi is actually a great drug in this case as it gives you more potent combined beta and alpha effects. The pt's LV function is probably at least moderate to severely impaired at that pH. Pure phenylephrine is only adding afterload. Epi is similar to norepi but nowhere near as strong for a situation like this.

I disagree, I think a swan would be indicated as she appears to be in severely decomponsated shock of some sort and doesn't appear to be responding to the treatment they were giving her, a continuous SvO2 monitor would be nice to see as well. (SvO2 monitoring is, IMO, one of the most important numbers in situations like this) While they did not do enough to correct her acidosis, a PA cath definitely would help guide her treatment plan, studies have shown that even the most seasoned health care professional accurately guesses the correct filling pressures as little as 30% of the time. While, I agree with you that we do not have enough information to accurately guide care I disagree on your take that Epi wouldn't help. If it's a pump failure due to acidosis, I highly doubt that thats the only problem, Epi would improve contractility. If she's giving birth she's young enough to tolerate a pH of 7.19 without having complete circulatory collapse. Something else is going on here, sounds like a possible embolism and dying tissue. As I said earlier, I don't think her volume status was optimized and if you're to the point where you're running wide open norepi, there are other options to consider, such a swan and other vasopressive/inotropic agents.... I'd also maybe try an amp of Calcium Chloride as well.

Edited by richard1980

The swan could tell us if she is in cardiogenic vs. septic shock.

I disagree, I think a swan would be indicated as she appears to be in severely decomponsated shock of some sort and doesn't appear to be responding to the treatment they were giving her, a continuous SvO2 monitor would be nice to see as well. (SvO2 monitoring is, IMO, one of the most important numbers in situations like this) While they did not do enough to correct her acidosis, a PA cath definitely would help guide her treatment plan, studies have shown that even the most seasoned health care professional accurately guesses the correct filling pressures as little as 30% of the time. While, I agree with you that we do not have enough information to accurately guide care I disagree on your take that Epi wouldn't help. If it's a pump failure due to acidosis, I highly doubt that thats the only problem, Epi would improve contractility. If she's giving birth she's young enough to tolerate a pH of 7.19 without having complete circulatory collapse. Something else is going on here, sounds like a possible embolism and dying tissue. As I said earlier, I don't think her volume status was optimized and if you're to the point where you're running wide open norepi, there are other options to consider, such a swan and other vasopressive/inotropic agents.... I'd also maybe try an amp of Calcium Chloride as well.

You need to correct the acidosis first. If we're talking about real world approach to this problem (not textbook), you normalize the ABG, aggressively administer volume (using CVP to guide your resuscitation) and use pressors for interim support. While your coding her shock state you're getting full labs. Positive trops, CXR, echo findings etc would guide you towards a swan if you suspect a cardiogenic cause but you would not use a SGC as a measure of filling. CVP and TTE are less invasive, and echo is more useful. There's a reason swans have had a moratorium in many centers- they're notoriuously misused.

Second, I don't disagree that epi would NOT help, but norepi is the first line drug here. Vasopressin and dopamine are useful as well. You're simply not going to get the alpha effects you need in decompensated acidosis with epi alone. Assuming this is only due to acidosis. If she has a major PE then you're in a different ballgame, different stadium.

richard1980

Specializes in SICU/CVICU. Has 7 years experience.

You need to correct the acidosis first. If we're talking about real world approach to this problem (not textbook), you normalize the ABG, aggressively administer volume (using CVP to guide your resuscitation) and use pressors for interim support. While your coding her shock state you're getting full labs. Positive trops, CXR, echo findings etc would guide you towards a swan if you suspect a cardiogenic cause but you would not use a SGC as a measure of filling. CVP and TTE are less invasive, and echo is more useful. There's a reason swans have had a moratorium in many centers- they're notoriuously misused.

Second, I don't disagree that epi would NOT help, but norepi is the first line drug here. Vasopressin and dopamine are useful as well. You're simply not going to get the alpha effects you need in decompensated acidosis with epi alone. Assuming this is only due to acidosis. If she has a major PE then you're in a different ballgame, different stadium.

Absolutely levophed is the first drug of choice but if she's further decompensating perhaps its cardiogenic and epi and perhaps a swan would be indicated. We uses swans every day in my unit. Vigileos are, imo, garbage. The pt can't be tachy or afib and according to Edwards all their test subjects were intubated, sedated and paralyzed in NSR. Of course you have to look at everything, and no, i don't automatically jump to, lets swan them. But a swan is indicated in severe shock which she clearly is in. The criteria for a swan, which I'm sure you're familiar with are as follows:

Diagnosis of shock states - check

Differentiation of high- versus low-pressure pulmonary edema

Diagnosis of idiopathic pulmonary hypertension

Diagnosis of valvular disease, intracardiac shunts, cardiac tamponade, and pulmonary embolus (PE) possible check

Monitoring and management of complicated AMI

Assessing hemodynamic response to therapies - check

Management of multiorgan system failure and/or severe burns - possible check

Management of hemodynamic instability after cardiac surgery

Assessment of response to treatment in patients with idiopathic pulmonary hypertension

In my facility, depending on the intensivist working, she would probably get a swan.

I really think the whole idea of not using swans has gone too far. We used to swan everyone. Now it's fallen out of favor, wouldn't surprise me to see it fall back in favor, kinda like how levophed was out of favor for quite a while...now its very popular

Maevish, ASN, RN

Specializes in ICU, Postpartum, Onc, PACU. Has 9 years experience.

I haven't been on here for awhile and seeing all these replies is great! I think I had failed to mention that after she'd gotten 8L NS and a couple units of blood (before the "stat" echo) that her EF was 10%! Unbelievable....now it's so far removed that I don't remember more of the details, but you guys have helped so much! :-)