Is dural puncture epidural (DPE) the optimal labor analgesia technique?

Welcome back to Depth of Anesthesia. I'm David Hao, and I'm an anesthesia. resident at the Massachusetts General Hospital. This episode will be featured on Anesthesiology News, an excellent resource for timely updates in our specialty. My guest today is Dr. Ronald George. He is professor and chief of obstetric anesthesia at UCSF.

If you want to connect with him on social media, his Twitter handle is at Ron underscore George. Dr. George, welcome to the show. Thank you, David, and thanks for the invitation and for all your hard work in creating such a great evidence and expert-informed podcast for us hard-working anesthesiologists. I hope I can share some experience and evidence from epocetric anesthesia with regards to labor analgesia. And I hope all your listeners are staying safe, practicing the necessary physical distancing and masking to reduce the spread of the coronavirus.

Well, thank you for being a listener yourself, and I hope everybody who's listening is staying safe in these trying times. I'm absolutely looking forward to your insights on our first ever obstetric anesthesia topic. Our case today is that of a 24-year-old G2P1 who presents the labor and delivery floor. She requests neuroxial anesthesia. She mentions to the anesthesiologist that she progressed very quickly with her first pregnancy and had significant pain while waiting for the epidural to take effect.

Hearing this, the obstetrician mentions to the anesthesia team that they would prefer to avoid a combined spinal epidura due to possible adverse effects on the fetus. The anesthesiologist therefore elects for a dural puncture epidural technique. Thanks, David. This is a very common situation that we face in the labor and delivery unit. And I'm used to working in an environment where the decisions regarding how to initiate neuraxial labor analgesia are left up to the capable obstetric anesthesia team to make evidence-informed decisions that are based on the current patient factors.

All forms of labor analgesia have potential to have effects on the fetus, and it is most important to deliver a safe technique specific to the patient and current situation. The claims in this case can be summarized as follows, that a dural puncture or DPE technique improves the analgesic quality versus traditional epidurals. that a DPE technique has a faster onset of analgesia versus the traditional epidural, and that a DPE has less adverse effects compared with combined spinal epidural. To our listeners, what's the level of your agreement with the claims that Dr. George has presented here? And what is the level of evidence for what you believe? I know from my own experience in the obstetrics unit that slow onset of labor analgesia it can be hugely impactful to our patients.

So I'm really excited to be able to explore the evidence for many of the rationales that physicians may use when considering alternative methods like DPE and CSE for their patients. Yeah, and this patient's concerns for the delay of the effect of epidural anesthesia is a common one that I hear from moms having their subsequent children and when they're trying to recount how their epidural went the last time. In some cases where labor does progress quickly, some moms will comment that the epidural didn't even work at all, as they never had that period where they achieved satisfactory analgesia. This is one reason I personally started to routinely use a combined spinal lipidural or a DPE technique.

We know from the published data with regards to caesarean delivery that moms value pain management greater than the concerns over side effects. And we did present some data in an abstract at last year's Society of Epistetic Anesthesia and Perinatology meeting. And we're working on the publication of that data, so it's not peer-reviewed yet. But this data did confirm that moms in labor value achieving desired pain relief in a short amount of time more than their concerns over common side effects of neuroaxial labor analgesia. So Dr. George, I think it would be helpful if we just start off with explaining what exactly a dural puncture epidural technique is and how that differs from a combined spinal epidural and a traditional epidural.

So, as most might already know, a traditional epidural uses a TUI needle to place a catheter in the epidural space through which we inject a combination of local anesthetics and opioids. that slowly make their way to the site of action to provide labor analgesia. The combined spinal epidural threads a needle through that epidural needle to puncture the dura and inject medications into the intrathecal space to deliver a more rapid form of labor analgesia. With a dural puncture epidural or DPE, that dural puncture is created with the same type of spinal needle, but no intrathecal medications are injected. Rather, we remove the spinal needle and thread the epidural catheter and inject epidural medications, which we believe a portion of these epidural medications will more rapidly translocate from the epidural space to the intrathecal space and possibly improve the speed of onset There have been a few small studies that have tried to evaluate the DPE versus traditional epidurals and combined spinal epidurals.

And the important thing to know is that the current body of literature does have significant heterogeneity. There are inconsistent and sometimes not clinically meaningful findings with respect to faster onset of analgesia or reduction in adverse effects of other neuroactive analgesic techniques. So we'll start this podcast with some studies addressing various claims related to DPE and then summarized with a nice systematic review. We'll also have a study that compares DPE, CSE, and traditional epidurals versus one another. As far as I'm aware, one of the initial proposed advantages of DPE was the ability to confirm proper epiduro location.

What evidence do we have that this is the case? So some of the original thoughts regarding this confirmation of placement and sustained success of epidural catheters was a study from Lydia Groden and the group at Wake Forest University. which highlighted the possible benefits of confirming identification of a midline epidural. When they evaluated those attempted CSEs for which they did not detect any cerebral spinal fluid through the spinal needle, the epidural catheter replacement rate was significantly higher. And this is an important tool that I use every day when teaching and working with residents on a regular basis. Coincidentally, one of the first studies evaluating a DPE compared to conventional epidurals came from the same group at Wake Forest University.

In this study, Thomas did a dural puncture with a 27-gauge needle and evaluated the epidural catheter function and the quality of labor analgesia. However, neither of these outcomes were significantly different between the groups, and there were significantly higher rates of complications and catheter manipulation in both groups which I believe highlights some of the concerns for the overall technique within this study. Do we have any evidence to suggest that onset of analgesia is better with DPE when compared to traditional epidurals? Well, I think it's also important to identify what is an important time in time interval from analgesia. So when I do a combined spinal epidural in my practice, I'm looking to see that a patient is significantly more comfortable by the time I'm securing the epidural catheter and lying the patient back down.

Wilson and their group evaluated whether a DPE versus a conventional epidural could achieve a more rapid onset of analgesia, measured at 10 minutes after the procedure. Using a 26-gauge spinal needle for the DPE, they showed that the percentage of parturients with adequate labor analgesia 10 minutes after the initiation of the epidrocatheter bolus did not differ by their neuraxial technique. These two last studies, the one by Wilson and Thomas, Likely also highlight the need to puncture the dura with a spinal needle greater than or equal to a 25 gauge needle. So it sounds like the primary outcome in this study was comparing the percentage of Parturians in each group with VAS scores less than 10, and that was on a 100 millimeter scale.

And the assessment was done with an active contraction ten minutes after the epidural bolus, is that right? That's correct. And that is a common measure of analgesic success. Sometimes you need to ask, is less than or equal 10 millimeters the um a reasonable goal Some people will study smaller uh improvements, i. e. uh less than three or thirty millimeters on a hundred millimeter VAS. And then you need to consider whether or not ten minutes is the appropriate the appropriate interval. for achieving analgesia.

Some would aim for a little bit shorter and some would suggest that with epidural medications that actually probably is gonna have to be longer. So I think we don't have consistent use of pain measures in many of these studies, which is part of the heterogeneity that I mentioned in the series of these projects Yeah, and I think that's a really great point in that clinical significance doesn't always mean the same thing to different clinicians or even patients for that matter. It's certainly important to dive into the literature and and understand what's statistical significance versus clinical significance Exactly. Um when constructing trials of labor analgesia, I think it is incumbent upon us to start to really evaluate the important outcomes that we should be studying, ensuring that they are patient-focused, patient-centered and have clinical meaningfulness.

These are what we should be studying. And in many cases, we should be including patients in how do we determine what is clinically meaningful. And what about the claim that DPE improves analgesic quality versus traditional epidurals? Are there any studies out there evaluating the quality of these techniques in terms of pain relief? So there have been some evaluations of the quality of analgesia measured by comparing the degree of sacral spread, sacral spread of analgesia, specifically analgesia at the S1 or S2 dermatome.

Now, the study I mentioned earlier by Thomas in their group of parturians of mixed parity found no significant differences in the quality of labor analgesia, i. e. the amount of sacral sparing that was found in one group or the other. Now, another study by Capiello from the Brigham in Boston in a randomized trial of DPE technique compared with a conventional epidural technique. Punctured the duro with a 25-gauge needle in the DPE group. They evaluated the S1 dermatome blockade analgesic score within 20 minutes of the initiation of the epidural And the likelihood of achieving either an S1 sensory block at 20 minutes after initiation was not different between the DPE and the epidural groups. Now achieving that S1 sensory block at any time during the study was more common in the DPE group.

But when I look at the methodology and how this was evaluated, to me it's not clear that we can say that this was the result of the DPE, as these patients were also using patient-controlled epidural analgesia, which may influence their degree of analgesia at later points in labor. Got it. So it seems that the likelihood of unilateral or bilateral S1 sensory block was the same within 20 minutes between both groups. But if evaluated over the entire study period, the likelihood of achieving that was higher with DPE. Yeah, and some of these um nuances that they found are are sometimes hard to interpret when it's not the primary outcome of the study and how they powered their study um in terms of trying to figure out um and and allocate patients to different groups.

So I I sometimes I'm reluctant to dig too deep into secondary exploratory outcomes Yeah, I think that's really fair. And so uh on the basis of these findings and some of the studies that we've mentioned, we have a systematic review now of some randomized control trials that might shed some more light on this topic. So Dr. Heeson and his collaborators have published a number of important systematic reviews in epistetric anesthesia in the last couple of years. And one of the important ones from my standpoint was the comparison between DPE and traditional epidurals. Now, the main conclusion that you can draw from this review, as I mentioned earlier, was that the body of literature regarding this labor analgesic technique has significant heterogeneity.

There's significant heterogeneity in the types of needles used to puncture the dura. There is heterogeneity in what type of solution they're using and what volume of solution they're using in the epidural space as part of the DPE technique. and how this might influence translocation of medications from the epidural space to the intrathecal space. This is compounded with significant differences in what is deemed to be the most appropriate primary outcome. which makes it challenging in making some of these concrete decisions when you look at a systematic review of this type. Now we, along with patients, do need to consider what is a meaningful improvement in the speed of onset, as I mentioned earlier. And how best can we define quality of analgesia?

And is sacral spearing the most meaningful and patient -centric manner of evaluating quality of analgesia? Lastly, we in the OB anesthesia community need to do larger multi-center studies so that we can identify more rare outcomes like fetal heart rate abnormalities. Such that we can make better conclusions about the impact of the analgesic options that we have for our patients. Those are definitely some important things to think about and consider for the future of OB anesthesia. In spite of the significant heterogeneity as you mentioned, this systematic review did conclude four significant findings from the five randomized control trials.

They observed that when DPE was compared to conventional block, there was a two-minute shorter median time to achieve sufficient analgesia, eight minutes versus ten. Again, that could be argued as not clinically meaningful There were a larger number of women having a VAS score of less than 10 out of 100 at 20 minutes. There was an overall reduction in number of epidural top-ups. and better sacral analgesia, as indicated by a higher percentage of patients having an S1 block in one study and an S2 block in another study. Yeah, and I think this, as we've already mentioned, sort of highlights um key aspects of trying to identify the appropriate outcomes. I would have a hard time Contemplating whether a two-minute me improvement in median time to achieve sufficient analgesia is clinically meaningful In the timeline in which I'm caring for patients and seeing how the epidurals work, two minutes is a blink of an eye, and it just doesn't seem clinically meaningful to myself Now, that might be different if we included patients in how we make this decision.

They might see that two minutes is very important I do think the reduction of epidural top-ups would be would be an interesting primary outcome in future studies. I think it is important in terms of the workflow. force uh evaluation of labor analgesia and if we're going to use these techniques in in centers where they don't have full-time obstetric anesthesiologist to oversee uh these patients But also I think it speaks to how patients interact with our delivery techniques and how things like DPE, CSE, or traditional initiations of epidurals interact with um programmed boluses or patient-controlled boluses of labor analgesia. So I think until we see studies that are properly powered to look at these clinically important outcomes, it's hard to make conclusions about them.

Yeah, I think that's really fair and and um I'm glad that you brought up a lot of those points and thinking about other things including the workflow. So I think now we'll move on to another paper that was published in 2017, which is fairly recent. And this paper is excellent because it does a cross-comparison of all the techniques. So that's CSE, DPE, and standard epidurals. Yes, uh this is this is happens to be one of my favorite studies for Ur.

For one reason, um it was led by a friend of mine and fellow Canadian Anton Chow, who is currently doing some great work in the in a wonderful city of Vancouver. But I do review it with a an as unbiased opinion as possible. This was a project he led while he was studying his research in obstetric anesthesia at the Brigham in Boston. And it highlights a lot of information that I like to discuss with residents and fellows because it was so well done methodologically. So what they did was compare a dural punctural epidural technique with a traditional epidural and a third group of moms who received a combined spinal epidural technique.

This was a randomized control trial of 120 women randomly assigned to one of these three groups. The initial dosing for the epidural and the DPE consisted of 20 mLs of. 0125% bupivicaine with fentanyl. a very common um epidural initiation uh mixture of medications while the combined spinal epidural group received 1.7 mg of bupivacaine and 17 micrograms of fentanyl as an intrathecal dose. Now in this study their primary outcome was the time to a numeric pain rating scale less than 1. Now the CSE group clearly had a significantly faster onset time in delivering analgesia with a mead median onset time of about two minutes. and with a very narrow range of variability, a very consistent delivery of good analgesia.

The DPE and the epidural were significantly longer. with a fair amount of a variability in um the the time to get patients to a satisfactory level of analgesia. And some patients in either group were not comfortable within the two hour study period window. Now, this faster onset clearly didn't come without some of its side effects. Compared with the combined spinal epidural The dural puncture epidural had a significantly lower incidence of paritis or itchiness and low blood pressure. Which, you know, you could evaluate that.

These some of these findings might be amendable to changes in the doses they use for their intracal medication or other procedures that took part during uh during the epidural placement. There was a slight increase in the risk of physician top-up intervention with the combined spinal epidural compared to the dural puncture epidural. But again, this might be offset by the number of patients who never achieved satisfactory analgesia in the DPE group Now with regards to fetal outcomes and specifically fetal heart rate abnormalities, there was no difference between the groups related to fetal heart rate decelerations. It occurred in all groups The combined spinal epidural group did have more episodes of uterine tachycystole and uterine hypertonus, which was a combined composite outcome, along with a higher instance of fetal heart rates. converting from NICHD categories one, converting to category two tracings.

But no differences in any clinical outcomes for the fetus or the moms in this study. And so in this study, they enrolled 120 patients in early labor and randomly assigned to the three groups And as you mentioned before, it's important to observe the primary versus secondary outcomes. Their primary in this case was time to numeric pain rating scale less than or equal to one. And secondary outcomes included block quality, maternal adverse effects, uterine contraction patterns, and fetal outcomes Yeah, and I hope that we will see more studies similar to this methodology looking at these different techniques that will hopefully address some of the secondary outcomes. um here in a less exploratory manner. Things like fetal outcomes or fetal heart rate abnormalities are an important outcome and an important consideration.

And I know that it weighs on a lot of anesthesiologists' minds when they're determining what technique they're gonna do. And I just feel that the this area Needs better evidence before you can ultimately say that one technique is superior over another Yeah, and I absolutely agree. And it just in the course of doing literature review, it's clear that there are some studies and there's some evidence, but heterogeneity is very real. And and as we've discussed, it's difficult to draw any conclusive outcomes, it appears, from from what we currently have. Yeah, and when you look at the body of evidence, looking at um combined spinal epidurals and dural puncture epidural techniques.

You'll see a large range of some of these secondary outcome findings such as fetal heart rate abnormalities that are not replicated from time to time and it really Really makes you question the validity of some of the previous findings. And so I think we do need better control trials specifically looking at these outcomes, and preferably done in um as larger uh numbers in and in and and larger number of institutions involved in these to help reduce uh some of this heterogeneity and make things a little bit more generalizable So Dr. George, all in all, what is your assessment of the evidence surrounding practices with respect to CSE, DPE, and standard epidurals? So in the end, as we've highlighted a number of times, there's more work that is needed to be done in this area.

But I think from the current body of evidence. We do see that using a spinal technique, whether it be dural puncture or combined spinal epidural, does give us a measure of quality of our epidural catheter and confirming that we're in the midline and that's a valuable tool. And I think there is a trend towards seeing an improved quality in terms of if you think sacral sparing uh at some point in the uh during the labor is a reasonable measure of of analgesic quality But I think you can achieve that quality with any of these techniques, which is outlined in that evidence. Whether or not a DPE leads to a faster onset, I think right now we are seeing it probably does trend towards increasing the speed of onset compared to traditional epidurals.

It is not and comparable to combined spinal epidurals in any of this evidence. But I do think we also need to define What is an important length of time interval in terms of onset of analgesia comparing duralpuncture epidurals to traditional epidurals? And lastly, I think I would like to see once again more evidence highlighting some of the secondary outcomes and adverse effects that are measured in many of these studies. And I think those should be translated into primary outcomes in larger trials. For instance, uh I d I think it's evident that things like hypotension and puritis are likely to be more common if you put certain medications in the intrathecal space like you would with a combined spinal epidural.

But I think outcomes such as fetal heart rate abnormalities, it the evidence is not clear on that. And I don't think you can say that a DPE offers a clinically meaningful improvement on those sorts of outcomes at this stage. Dr. George, thank you for taking the time out of your busy schedule to discuss the evidence with me. I think this discussion and your insights will help shape the clinical practices of our listeners. Thanks, David.

This has been a real treat. love to talk about evidence-informed Libra analgesia and I appreciate the opportunity to share my thoughts and review some of this evidence with your listeners. Thanks for joining us on the show today. As always, please feel free to reach out to me on Twitter at Depth Anesthesia. If you have any topics that you'd like to hear a literature review on, please let me know. Please rate the podcast and share.

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