Cause of uneven pulse/ox wave form

[anon456, BSN, RN]

I took care of a child recently who did not have any invasive monitoring. Just standard EKG and pulse/ox. I noticed that the waveform on the pulse/ox would show one high, strong wave, followed by one slightly lower, and then one lower than that. Then it would start all over again in groups of three from tall to medium to low. I was unable to determine why and the RN's I asked were also unsure why it was happening. Other VS were stable in the child. Any thoughts?

[rnkaytee]

I don't know if I've seen it necessarily in that pattern but the most frequent causes are low temp of the extremity, poor perfusion or needing a new pulse ox/position change.

[NotReady4PrimeTime, RN]

Does your display look like this?

This waveform represents pulsus paradoxus. It's the physical manifestation of a drop in systolic BP >10 mmHg with inspiration. It may be caused by such things as pericardial effusion, cardiogenic shock, pulmonary embolus, tension pneumothorax, asthma, chronic lung disease, anaphylactic shock, SVC syndrome or obesity. If the patient had an arterial line a similar pattern to the waeform would be seen. Without more information about the patient it's hard to guess as to which cause is present, but given the likelihood of chronic lung disease in certain segments of the pediatric ICU population, that's where I'd go.

[anon456, BSN, RN]

Thank you! That actually makes sense considering their history and what we were doing for the patient. I have never seen that in "real life" before.

[brewski09]

Was the patient having bigeminal PVC or PAC (really any premature beats)? I've seen something similar to what you described in adult patients where the second beat does not produce as big of a pulseox waveform because of the decreased preload caused by premature second contraction of the heart. I would make sure the MD was aware of this, but they may not do anything if the patient is otherwise stable.

[cinlou, BSN, MSN, RN]

remember that with peds most cardiac issues are based on their respiratory status and does no necessarily mean that there is anything that is wrong with their cardiac status. Remember when you were taught to always count respirations and pulse on little ones for a full minute, irregularities are normal in the young population. But the Doc should be notified, they may want to check out other things CXR etc. Peds triangle, what do they look like?

[anon456, BSN, RN]

remember that with peds most cardiac issues are based on their respiratory status and does no necessarily mean that there is anything that is wrong with their cardiac status. Remember when you were taught to always count respirations and pulse on little ones for a full minute, irregularities are normal in the young population. But the Doc should be notified, they may want to check out other things CXR etc. Peds triangle, what do they look like?

This patient was a known cardiac case with systemic symptoms of heart failure and pulmonary congestion. We were treating accordingly and the patient was improving a bit. In this case reporting it would not have really changed the treatment plan. Now I know that if I see that again, to call the MD and look for other signs related to it. Love these boards, I learn so much! :-)

[aCRNAhopeful]

Not a PICU nurse but I had a couple thoughts. I am an anesthesia student with experience mostly in adult CVICU and now anesthesia FYI but I think the concept is relevant in pediatrics as well. I agree with the previous poster regarding the pulsus paradoxus. To go a little further you will see it anytime positive intrathoracic pressure causes significant decrease in venous return. If the pt is intubated the decrease in the pulse ox waveform or art line tracing will occur during inspiration and if spontaneously breathing it will occur during expiration due to positive pressure collapsing the vena cava and thus decreasing venous return/pre-load, thus decreasing stroke volume and blood pressure for those brief periods. With adults (and for the life of me I cant think why it wouldnt be the same for peds) this is a sign that someone is VOLUME responsive. Is the patient hypotensive with significant variability in the aline and/or pulse ox waveform with risk factors for hypovolemia: the BP will likely respond to a fluid challenge. This is the concept that the vigileo/flowtrack monitors use to calculate stroke volume variance (SVV). Other terms are systolic pressure variation, pulse pressure variation, SVV and they all refer to this phenomenon. So all the other causes like superior vena cava syndrome, tamponade, etc are all things you have to think about but I would say that the most common cause for this (at least in adults and surgical patients) is hypovolemia. Final caveat: seeing this on the monitor is not necessarily a bad thing, if everything else checks out OK then just note it and move on, maybe patient is just a tad on the dry side but still perfusing well, if so just leave it alone.

[anon456, BSN, RN]

Not a PICU nurse but I had a couple thoughts. I am an anesthesia student with experience mostly in adult CVICU and now anesthesia FYI but I think the concept is relevant in pediatrics as well. I agree with the previous poster regarding the pulsus paradoxus. To go a little further you will see it anytime positive intrathoracic pressure causes significant decrease in venous return. If the pt is intubated the decrease in the pulse ox waveform or art line tracing will occur during inspiration and if spontaneously breathing it will occur during expiration due to positive pressure collapsing the vena cava and thus decreasing venous return/pre-load, thus decreasing stroke volume and blood pressure for those brief periods. With adults (and for the life of me I cant think why it wouldnt be the same for peds) this is a sign that someone is VOLUME responsive. Is the patient hypotensive with significant variability in the aline and/or pulse ox waveform with risk factors for hypovolemia: the BP will likely respond to a fluid challenge. This is the concept that the vigileo/flowtrack monitors use to calculate stroke volume variance (SVV). Other terms are systolic pressure variation, pulse pressure variation, SVV and they all refer to this phenomenon. So all the other causes like superior vena cava syndrome, tamponade, etc are all things you have to think about but I would say that the most common cause for this (at least in adults and surgical patients) is hypovolemia. Final caveat: seeing this on the monitor is not necessarily a bad thing, if everything else checks out OK then just note it and move on, maybe patient is just a tad on the dry side but still perfusing well, if so just leave it alone.

Great explanation! Have you ever considered teaching?