IABP waveform clarification

  1. I had an IABP the other night on a patient awaiting CABG. 3VD, significant RCA and LMain involvement. The patient was slightly hypertensive on the IABP, he normally is on Lisinopril but they discontinued it prior to surgery. His pressures ranged from 110s-160s systolically on the IABP. Unassisted pressures ranged from 140s-170s. I had nitroglycerin up, which I was titrating as needed and he was bradycardic. We eventually gave IVP Hydralazine which brought his pressure down for a few hours.

    My arterial waveform was weird though, and I just wanted to know if it was because of the hypertension. My augmentation pressures were equal or less than my unassisted systolic pressures. And my diastolic unassisted and assisted were equal.
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  2. 8 Comments

  3. by   Ruby Vee
    When the patient is hypertensive, your augmented pressures will be the same as (or lower than) your unassisted systolic pressure. If his pressures were already 150-170, you're not going to get much augmentation. Were you getting good unloading? If your diastolic unassisted and assisted were equal, I'd say not. Did you try manually timing your balloon pump? I've found that sometimes helps, but it doesn't seem to be a skill that everyone learns these days. (I learned in 1983, before there was such a thing as automatic timing!)
  4. by   Catticus11
    So an equal assisted and unassisted diastolic is an indicator of poor offloading, in the setting of hypertension?

    Also, no I haven't tried manually timing. It was briefly reviewed to me by an older nurse (who also probably learned it in 1983 lol) but the waveforms appeared to be augmenting appropriately. I'm just still pretty new with balloon pumps maybe.
  5. by   PresG33
    The purpose of a balloon in this case is coronary perfusion, the "offloading" or increased cardiac output is very minimal with balloons, especially in a HTN patient (maybe a 0.5 l/min increase). His DBP is plenty high to perfuse the coronaries, so why did he have the balloon? If it was weaned off would he get chest pain? Sometimes our surgeons would put an IABP in a pre-op based purely on the cath report, which doesn't make sense unless they are hypotensive or have symptoms. It could be that your numbers didn't make sense because he didn't need the balloon. Whenever I couldn't get augmentation higher than the normal BP this was always a potential reason why.
  6. by   Catticus11
    Thank you so much for your response!

    So a low diastolic pressure would merit the balloon pump sheerly for coronary perfusion? Is there a particular DBP value that they decide for that? Does the type and grade of lesion have anything to do for an IABP indication? I thought it was because he was a 95% left main. Otherwise, I don't believe he was experiencing chest pain when he went into the cath lab (I could be wrong), and he was having issues with hypertension since arrivng from the cath lab for which I was told in report they initiated Nitro for. He also did start experiencing chest pain the day and night after I had him, requiring titration of nitro and IVP morphine with complete relief.
  7. by   PresG33
    The DBP needed for adequate coronary perfusion depends on the patients baseline BP, coronary anatomy, O2 demand, and lesions so there is t a set number. Generally a coronary perfusion pressure (MAP minus LVEDP or PAOP or CVP) of > 50 mmHg is targeted. As far as putting a balloon in based solely on lesion size or location, it may make the cardiologists feel better, but they aren't actually treating any specific symptoms and are putting patient at risk of bleeding from the balloon or PE/stroke from DVTs from laying perfectly still in a bed. An IABP is not a benign procedure and shouldn't be initiated on a pt without symptoms. That being said, if the pt had chest pain that was relieved by the balloon, that is a good reason to keep it in no matter what the augmentation is.
  8. by   ghillbert
    It also depends what his LVEF was. Often with a high grade lesion plus a bad EF, preop CABGs will get an IABP. If your actual balloon waveform was abnormal, you check your balloon placement first - was it in the right place on XR? Check the inflation signal waveform to see if it's inflating and deflating appropriately. Put it on pause or 1:2 and see if it changes the blood pressure. Try manually timing if required (or get your engineers or perfusion to, if they run the IABPs in your hospital).
    Definitely as a first step, if you are taking care of IABP patients, and before you try manually adjusting - you should know exactly what each waveform point is and what it means (dicrotic notch, augmented diastole, unassisted and assisted systole, patient end diastolic pressure and balloon-assisted end diastolic pressure) and what you are trying to achieve with your timing adjustments.
    Manufacturers have plenty of cheat sheets and info available on their websites.
  9. by   Catticus11
    Quote from ghillbert
    It also depends what his LVEF was. Often with a high grade lesion plus a bad EF, preop CABGs will get an IABP. If your actual balloon waveform was abnormal, you check your balloon placement first - was it in the right place on XR? Check the inflation signal waveform to see if it's inflating and deflating appropriately. Put it on pause or 1:2 and see if it changes the blood pressure. Try manually timing if required (or get your engineers or perfusion to, if they run the IABPs in your hospital).
    Definitely as a first step, if you are taking care of IABP patients, and before you try manually adjusting - you should know exactly what each waveform point is and what it means (dicrotic notch, augmented diastole, unassisted and assisted systole, patient end diastolic pressure and balloon-assisted end diastolic pressure) and what you are trying to achieve with your timing adjustments.
    Manufacturers have plenty of cheat sheets and info available on their websites.
    I'm sorry, I forgot to include that his EF per the cath was 50%. Per the CXR the IABP looked like it was in the right place. But waveform could also be affected by inappropriate position?

    When I put it in a 1:2 it did change, his unassissted pressures were higher 170s, compared to assissted which was 150s-160s. But I assumed that was a normal response.
  10. by   Pghfoxfan1
    Any "seasoned" nurses remember doing Endocardio viability ratios "EVR's" back in the "olden days" to wean IABPs? Oh, the good old days...

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