MONTEREY, CALIF. – Several factors, some of them modifiable, increase the odds of a failed conversion from epidural analgesia for labor to epidural anesthesia for cesarean delivery, concluded the first systematic review and meta-analysis of this issue.
The analysis found that 1 in every 20 women having an epidural in place and needing a cesarean had to undergo general anesthesia because the epidural could not be used for anesthesia, lead investigator Melissa E.B. Bauer, D.O., reported at the annual meeting of the Society for Obstetric Anesthesia and Perinatology.
Dr. Melissa E.B. Bauer
Women had a more than tripling of the odds of failed conversion if they needed two or more epidural analgesia boluses (so-called top-ups) during labor, had a general anesthesiologist instead of an obstetric anesthesiologist, or required a cesarean on a more urgent basis.
The findings underscored the need to investigate if a patient needs top-ups, according to Dr. Bauer. If a patient makes two or more requests for more analgesia, has breakthrough pain, and is really uncomfortable, she needs to be assessed to see if she has a nonworking epidural. If so, it needs to be replaced, she said in an interview, while noting that other factors, such as dystocia, may also be a cause.
The higher odds of failed conversion that are seen with a general anesthesiologist suggest that "people who manage labor and delivery more often are going to be a little bit more comfortable troubleshooting epidurals and trying to avoid a general anesthetic," commented Dr. Bauer, who is an obstetric anesthesiologist at the University of Michigan Health System in Ann Arbor.
The risk with an urgent cesarean may be the hardest to modify. "We can’t really do anything about that, except to have better communication of obstetricians and [obstetric] anesthesia; to say, if you tell us [a cesarean is coming], maybe we can run to the room and start bolusing that epidural so that by the time the [patient] gets to the OR, we have enough of a level so that [you] can start and avoid a general," she explained. "So the main points are, having more cooperation and also evaluating the [fetal-monitoring] strip, and saying okay, do we have 5 or 10 minutes to convert [the epidural] or not – those things might be helpful."
Dr. Brenda A. Bucklin, professor of anesthesiology at the University of Colorado at Denver, Aurora, and comoderator of a related poster discussion session, asked, "Are [obstetric] anesthesiologists less comfortable in providing general anesthesia for cesarean delivery?"
"I think that it’s the opposite," Dr. Bauer replied. "Since we provide anesthesia for pregnant patients on a daily or weekly basis, we have more familiarity with the obstetric airway, and we are also called to the main hospital to provide anesthesia on any pregnant patient there as well."
Dr. Bucklin also wanted to know, "Are [obstetric] anesthesiologists more likely to limp along with a bad epidural for cesarean delivery?"
"I would say no, but part of the difference is that we tend to troubleshoot our epidurals sooner because we can look at the fetal strips and say, oh, I think [the baby’s] coming, and we go and evaluate the patient on a regular basis," Dr. Bauer said. "Also, once a C-section is called, we’re in the room and we have some familiarity with the surgeons to see [if this is] really an emergency, is there time for me to bolus this. I think that [because of] those relationships and also our understanding of [obstetrics] in general, we have a decreased rate of general anesthesia."
There are several reasons to want to avoid a failed epidural conversion and have to resort to general anesthesia, she noted in the interview. Managing the airway in obstetric patients can be challenging, and there are risks associated with using another type of anesthesia on top of an epidural. "You always want the mother to be able to participate in the birth as well," she added.
The investigators identified 13 observational studies with a total of 8,628 women that assessed the rate of failed conversion and risk factors for this outcome.
Results showed that the percentage of patients having an epidural catheter in place who still had to undergo general anesthesia for their cesarean averaged 5%, with a range of 0%-21% across studies, reported Dr. Bauer.
Women’s odds of failed conversion increased significantly if they needed at least two clinician-administered top-ups of analgesia during labor vs. no top-ups (odds ratio, 3.2), had a general vs. obstetric anesthesiologist (OR, 4.6), or required a more urgent cesarean delivery (OR, 40.4).