Labor/C-section Epidural Fentanyl

[Mike1228]

Quick question about giving fentanyl through an epidural and the effect on the delivered baby.
Many providers giving 100 mcg fentanyl down the epidural when laboring mom is at or close to 10 cm and close to delivering since those sacral nerves are tough to cover (even tho I find siting them up and giving 5-10ml of 1% lido helps a lot). Fentanyl is also given before the start of C-section since it helps with visceral pain/pressure that makes patients uncomfortable and nauseous.....since epidural fentanyl is quickly uptaken systemically, shouldn't this practice run the high risk of neonatal respiratory depression?? Surprisingly, it doesn't and im confused because you wouldn't give 100 mcg of IV fentanyl right before delivery, so why is it different......

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[deleted875186]

Perhaps someone smarter knows the answer. I suspect because it gets absorbed much slower epidurally.

I don’t know why people say it’s basically like giving 100 mcg IV when you give it epidurally, I think it may be anesthesia dogma. Maybe it eventually is all absorbed systemically, but the clinical effects are definitely not as fast as IV, the effects usually last a good hour when through the epidural, it’s definitely much more potent epidural than IV, and there seems to be less risk of respiratory depression.

 

[nimbus]

[Repeated addition of fentanyl to bupivacaine peridural analgesia in labor. Clinical action and fentanyl plasma level] - PubMed

A combination of epidural opioids with local anaesthetics has been used to improve pain relief during labor and to reduce side effects, such as muscle weakness, usually seen when local anaesthetics are used alone. The addition of epidural fentanyl (F) produces highly effective analgesia, the...

pubmed.ncbi.nlm.nih.gov

 

[Mike1228]

Perhaps someone smarter knows the answer. I suspect because it gets absorbed much slower epidurally.

I don’t know why people say it’s basically like giving 100 mcg IV when you give it epidurally, I think it may be anesthesia dogma. Maybe it eventually is all absorbed systemically, but the clinical effects are definitely not as fast as IV, the effects usually last a good hour when through the epidural, it’s definitely much more potent epidural than IV, and there seems to be less risk of respiratory depression.

People say it's the same as IV fentanyl because, due to the crazy high lipophilicity of the drug, it most gets taken up by epidural fat, and then epidural veins into systemic circulation. Most of it does not go intrathecally. The duration of action is longer than OV fentanyl because there isn't a rapid redistribution that you see with IV fentanyl.....that's what I think haha. Clearly I'm wrong, bit I just don't how and it's annoying me a lot lol

 

[Mman]

since epidural fentanyl is quickly uptaken systemically, shouldn't this practice run the high risk of neonatal respiratory depression?? Surprisingly, it doesn't and im confused because you wouldn't give 100 mcg of IV fentanyl right before delivery, so why is it different......

while some of it is taken up systemically, it does not happen that fast, certainly not like pushing the same dose in an IV.

 

[gcc322]

Had a new OB start at my hospital. For inductions not in active labor and not eligible for an epidural (also dumb) he ordered 100mcg IV fentanyl q2 hour. Just saying…

 

[dabears505]

Had a new OB start at my hospital. For inductions not in active labor and not eligible for an epidural (also dumb) he ordered 100mcg IV fentanyl q2 hour. Just saying…

Do you think they should get an epidural before being in labor?

 

[gcc322]

Do you think they should get an epidural before being in labor?

I think if the patient is in early labor (<4cm) and desires an epidural she should not be denied it and offered pain medication in its place.

 

[deleted162650]

Do you think they should get an epidural before being in labor?

If it’s an induction, where there is zero chance the patient is leaving the hospital without delivering, then sure - why not?

 

[Beeftenderloin]

Do you think they should get an epidural before being in labor?

I don’t presume to tell the patient when they’re in enough pain to warrant an epidural. If they’re uncomfortable enough to commit to being bed bound and cathed in the name of pain control, I’ll place it.

 

[GassYous]

Do you think they should get an epidural before being in labor?

Why not? Better than asking for it when the babys almost out

 

[sevoflurane]

Why not? Better than asking for it when the babys almost out

100%. Worked at the biggest OB hospital in Pennsylvania. Nothing wrong with a dry epidural running at 1cc/hr. Then titrating up as the oxy kicks in.

 

[Mike1228]

Back on topic haha....so no one knows why 100 mcg of epidural fentanyl ~60 mins-ish before delivery doesn't affect fetal APGAR scores?

 

[Mman]

Back on topic haha....so no one knows why 100 mcg of epidural fentanyl ~60 mins-ish before delivery doesn't affect fetal APGAR scores?

because very little of it gets to the fetus, seems obvious right?

 

[Beeftenderloin]

A Review of the Use of Fentanyl Analgesia in the Management of Acute Pain in Adults | Anesthesiology | American Society of Anesthesiologists

The minimum effective plasma concentration (MEC) of fentanyl to produce statistically significant analgesia is somewhere in the range of 0.6-3ng/ml. Some studies quote an even wider range (0.6-8ng/ml). An epidural bolus of 100-200mcg of fentanyl will reach a plateau systemic concentration somewhere in the range of 0.3-0.86 ng/ml after approximately 10-30min. Although at the higher end this might achieve some degree of analgesia is some patients, in many patients it wouldn’t be enough to achieve any analgesia at all, let alone respiratory side effects. The primary mechanism of dense analgesia we see is mediated centrally. The amount that actually gets absorbed systemically both takes longer (10-30 mins to peak IV conc. as opposed to nearly immediately with IV) and results in relatively modest peak plasma concentrations, and that’s just in mom.
Placental Transfer and Neonatal Effects of Epidural Sufentanil and Fentanyl Administered with Bupivacaine during Labor | Anesthesiology | American Society of Anesthesiologists

Now yes, fentanyl can cross the placenta. And yes, the neonate will be more sensitive and not clear the drug as quickly. But the above study found that the ratio of fentanyl present in the umbilical vein relative to the maternal vein (UV/MV) was only 0.37 +/- 0.08.

So you already have a relative low concentration that slowly makes its way into moms blood, and an even smaller fraction of that actually crosses over to baby. And that’s all assuming you time up delivery to coincide exactly with peak plasma concentration, which likely isn’t happening that often.

TLDR: Because very little of it gets to the fetus.