I've spent the last few nights pondering this question ... let's use a "hypothetical" patient: Primip, induction (cytotec X2 then Pitocin), Pit is up to 6mu, FHR baseline 140-150bpm with average variability and accels up to 175, UC's q 3-6 minutes, 60-90 seconds long. Late decels are noted, first deep then more subtle (understanding that it is not resolving but that the baby is having more difficulty with the UC's). Patient is repositioned to left lateral, HOB flat and IV open. Mom shows 99% oxygen saturation on RA. FHR return to baseline with no further problems.
Would you put O2 at 8-10L via mask on this patient? Why? My first (new nurse) thought would be to apply oxygen but when I saw her O2 sat at 99%, I hesitated. Another RN came into the room and immediately applied the oxygen mask. After the day was over, I spent some time online searching for evidence proving that oxygen administration would have helped the mom and/or fetus. Interestingly enough, there was nothing that I could find that was definitive regarding supplemental oxygen when mom is already at 99% on RA.
What do you all think? I'd love some other input. Are we applying O2 as a habit without evaluating the moms current O2 saturation? Is it beneficial when she is already at 99%? Would love to hear what you all think about this!
Incidentally, went to the OR for a c/sec (hours after the lates resolved themselves), mom was tired of being in labor and doc was tired of listening to her ask for a c/sec. Bummer, too, since the patient was obese making her post-op recovery harder. No nuchal cord found, placenta looked great and baby labs all WNL.
It doesn't matter what the pulseox is reading...that probe is picking up the sat of the cells in that finger at that time. Sometimes, when you draw an ABG on someone that is sating 99, their O2 can be low. There is no way to know if that pulseox is totally correct without doing an ABG.
Right, we see this in the NICU all the time. We can have a patient who is saturating 100% but on the arterial blood gas, their oxygen level is low. If we increase their inhaled oxygen, they're still saturating 100% but on the blood gasses, we'll see an increase in the blood oxygen level.
I don't know how to explain it either. It's been awhile since I've studied pregnancy and fetal circulation! Maybe I should do some research?
Hmmmm...let me think here...
Okay, sometimes we'll have a newborn who we start on oxygen via a cannula or vent. We'll have them at 100% and then we'll get the blood gas and the oxygen level is through the roof. So we'll decrease the inhaled oxygen and eventually we'll see a decrease in the blood gas oxygen level as we go. The baby may be saturating 100% this whole time, but there is actual proof in the labs that the oxtra oxygen DID affect the baby when it was being given even though the sats didn't change.
ETA: I guess this would mean that even if the mom is saturating 99 or even 100%, applying oxygen will still increase the amount of oxygen in her blood and thus provide extra oxygen to the baby.
Okay, so I think we've come got two things going here:
1) If the patient shows an O2 sat of 99%, it may not actually be so (inaccurate reading of a finger pulse ox), so additional oxygen makes up for any deficiency. Thus, the reasoning behind applying O2 when we see fetal distress ... extra 02 to mom, more to the baby, better outcomes.
2) If a patient has a TRUE oxygen saturation level of 99-100% (proved by an ABG draw - which is not going to happen in L&D), then additional oxygen would be unnecesary as the patient's hemoglobin would be carrying a full load of oxygen and would be unable to carry more to the baby.
So, to answer my own question, giving 02 @ 10L via mask is based on the asssumption that mom may not actually be satting at what we see on the monitor and we give the 02 to ensure that the baby has the biggest oxygen supply from which to draw from, especially when facing distress.
Edited to add: I'm going to research the Oxyhemoglobin Curve for more info .. I'm thinking that with a low H&H, less hemoglobin to carry O2 ... I'm not sure I'm even following myself at this point.
Anymore ideas?
You are on the right track to be interested in the oxyhemoglobin curve.
Remember, if a patient is anemic, it is possible for her hemoglobin to be fully saturated with oxygen, and yet the patient still be hypoxic. Conversely, if a patient has an abnormally high Hgb, it is possible for her to be only 80% saturated, appear cyanotic, and yet have an adequate supply of oxygen in her bloodstream.
Thanks for asking these questions. It keeps all of us focused on the scientific rationale for what we do!
Oxygen saturation IS NOT the equivalent of paO2.
right on! the oxyhemoglobin curve helps us understand what kind of o2 is being delivered and released.
1) If the patient shows an O2 sat of 99%, it may not actually be so (inaccurate reading of a finger pulse ox), so additional oxygen makes up for any deficiency. Thus, the reasoning behind applying O2 when we see fetal distress ... extra 02 to mom, more to the baby, better outcomes.
This is a fun puzzle you brought up. I see your rationale of making up for the inaccuracy of the pulse oximeter. It would be very interesting to observe the relationship between fetal distress and giving the O2 mask to the mom, given a constant SaO2.
We can have a patient who is saturating 100% but on the arterial blood gas, their oxygen level is low. If we increase their inhaled oxygen, they're still saturating 100% but on the blood gasses, we'll see an increase in the blood oxygen level.
As I understand it, the PaO2 is based on the plasma O2, and by the nature of oxygen dissociation curve, PaO2 can vary quite widely without any changes to the SaO2, as long as the PaO2 is over 60 mm HG.
Specializes in Education, FP, LNC, Forensics, ED, OB.
The fetal oxygen supply can be decreaed during the labor process by decreased circulation through the intervillous space of the placenta, thereby decreasing fetal perfusion. Most healthy fetuses can compensate for this. But, if the fetus is showing s/s of stress as indicated on the FH monitor, oxygen administered to the gravida will increase perfusion.
One of the goals of FHR monitoring is early detection of mild fetal hypoxemia. This is indicative of decreased oxygenation in the arterial blood. Another goal is to prevent the fetus from developing severe hypoxemia (which is an inadequate supply of oxygen at the cellular level), and therefore progress to fetal hypoxia. The nurse MUST attempt to ensure adequate oxygenation/perfusion. This is done by employing the intrauterine resuscitation measures (see this in post above).
What an excellent thread this is. It is difficult sometimes to not dwell on SaO2 and really look at what you are doing with oxygen and PaO2. Intrauterine resusitation involves taking a PaO2 to over 300% (in the mom) to really effect the fetus. You are hyper oxygenating the mom to get to the baby.
Only one thing I want to interject....
Late decels in the presence of accels are not neccesarily a bad thing. The accels are telling you that you have an oxygenated baby, the late decels can sometime be "reflexic"...placental reaction to contractions. You said you had a deep late first...was it a variable??? You can have variables that occur after a contraction, but the pathophysiology is still the same..it is a cord compression...and therefore..move that mom's position. The subtle lates you described also need position changes. Not seeing the strip, but hearing what you described...I don't know that I would've applied O2...but there is an inherent lesson we have all learned over the years in OB..when you see lates you put on O2. Look at the big picture and not what is occuring at that minute. What is the baby saying to you...telling you what it needs? It is our job....as siri said...to be digilent in maintaining the baby and keeping hypoxia to a minimum...
Gompers, BSN, RN
2,691 Posts
Right, we see this in the NICU all the time. We can have a patient who is saturating 100% but on the arterial blood gas, their oxygen level is low. If we increase their inhaled oxygen, they're still saturating 100% but on the blood gasses, we'll see an increase in the blood oxygen level.
I don't know how to explain it either. It's been awhile since I've studied pregnancy and fetal circulation! Maybe I should do some research?
Hmmmm...let me think here...
Okay, sometimes we'll have a newborn who we start on oxygen via a cannula or vent. We'll have them at 100% and then we'll get the blood gas and the oxygen level is through the roof. So we'll decrease the inhaled oxygen and eventually we'll see a decrease in the blood gas oxygen level as we go. The baby may be saturating 100% this whole time, but there is actual proof in the labs that the oxtra oxygen DID affect the baby when it was being given even though the sats didn't change.
ETA: I guess this would mean that even if the mom is saturating 99 or even 100%, applying oxygen will still increase the amount of oxygen in her blood and thus provide extra oxygen to the baby.