SAN FRANCISCO—“These papers will change your practice,” said Pervez Sultan, MD, an associate professor of anesthesia at Stanford University School of Medicine, in California, and an honorary professor at University College London, during a session on recent top papers in obstetric analgesia and anesthesia at the 2023 annual meeting of the American Society of Anesthesiologists. Here, we spotlight the six papers that Sultan and Michaela Farber, MD, an associate professor of anesthesia at Harvard Medical School and the chief of the Division of Obstetric Anesthesia at Brigham and Women’s Hospital, both in Boston, presented during the meeting.

Chronic headaches related to post-dural puncture headaches: a scoping review (Br J Anaesth 2022;129[5]:747-757)

“After an accidental dural puncture (“wet tap”), anesthesiologists typically focus on the acute management of spinal headache, but this scoping review confirms what a lot of the literature has been suggesting: Having a wet tap in labor is associated with a higher rate of chronic headache,” Farber said. The review examined 22 papers and found that the incidence of chronic headache after an accidental dural puncture was 38%, compared with 16% for women who did not have a wet tap in labor.

“This paper tells us that the resolution of an acute spinal headache may not be the end of the story after a frank wet tap,” she said. “Our patients deserve to know that chronic headache is a possible long-term complication, and we need to focus on closely documenting our management of spinal headaches and tracking patients longer to understand how we might mitigate the risk of chronic headache.”

Pregnancy and labor epidural effects on gastric emptying: a prospective comparative study (Anesthesiology 2022;136[4]:542-550)

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Accidental aspiration of gastric contents into the lungs is a rare but serious complication in obstetric patients, with high morbidity and mortality. “Women in labor can require emergency cesarean delivery at any time, and we don’t want to provide emergency anesthesia for patients who have full stomachs,” Farber said. “But the rate of aspiration is extremely low, and if guidelines stating that women in labor should have no solid food are strictly followed, some patients could go 24 hours or more without food. Can we be more liberal? Gastric ultrasound gives us the tool to explore this question.”

The new study used gastric ultrasound to compare four groups of women: nonpregnant, pregnant but not in labor, and pregnant and in labor with and without epidural analgesia. All were fed a single serving of yogurt and scanned over time. “Although gastric emptying was slower in pregnant women in general and even slower in laboring pregnant women, it was no slower in women with epidural pain relief than in those without,” she said. “Despite this finding, we should not yet change our overall rules for fasting in labor. However, this paper highlights gastric ultrasound as a tool we should use more commonly to help us stratify risk in advance of cesarean delivery, or possibly to liberalize food intake in labor in specific situations.”

Tranexamic acid dose–response relationship for antifibrinolysis in postpartum haemorrhage during Caesarean delivery: TRACES, a double-blind, placebo-controlled, multicentre, dose-ranging biomarker study (Br J Anaesth 2022;129[6]:937-945)

The use of tranexamic acid (TXA) in obstetric anesthesia has skyrocketed since the 2017 Woman Trial reported, as a secondary outcome, a lower risk for death from hemorrhage in women with postpartum hemorrhage treated with 1 g of TXA. “Current guidelines say we should give TXA for all cases of postpartum hemorrhage as early as possible, ideally within the first three hours after birth,” Farber said. “The next question for this medicine, now that we have given it to many women having postpartum bleeding, is, are we achieving the antifibrinolysis we want to achieve with a 1-g dose?”

The TRACES trial demonstrated that there is indeed a dose–response relationship with TXA. “They compared a full 1-g dose of TXA to 0.5 g and placebo in women having postpartum hemorrhage, using D-dimer as a surrogate for fibrin breakdown,” she said. “They found diminishing D-dimers with the middle and high dose. The take-home here is that a 1-g IV dose of TXA yields an antifibrinolytic effect that is dose dependent. Importantly, 1 g TXA should remain a treatment for postpartum hemorrhage after onset. Prophylactic use of TXA for postpartum hemorrhage is not supported by available evidence.”

American Society of Anesthesiologists statement on quality metrics (www.asahq.org/standards-and-practice-parameters/ statement-on-quality-metrics)

This statement, issued by the American Society of Anesthesiologists (ASA) Committee on Obstetric Anesthesia in October 2022, provides the first quality metrics in the United States for obstetric anesthesia. “This is the first time that we have a U.S. professional society giving recommendations for obstetric anesthesia–specific quality metrics,” Sultan said. “More and more, labor and delivery units are starting to perform quality improvement [QI] initiatives, and to do QI effectively, we need to know what to measure to see whether the quality of service we are providing is improving. I think these metrics will be very useful in these efforts, and hopefully will encourage labor and delivery dashboards to be used more frequently.”

Prevention and management of intra-operative pain during caesarean section under neuraxial anesthesia: a technical and interpersonal approach (Anaesthesia 2022;77[5]:588-597)

“Regional anesthesia is the gold standard for C-section patients; every professional society recommends neuraxial anesthesia in the absence of contraindications,” Sultan said. “It is associated with better maternal–neonatal bonding, better pain relief, is opioid-sparing and is the safest thing for mother and baby in numerous ways. But we need to know more about how often patients develop intraoperative breakthrough pain and what the potential long-term sequelae are. It is particularly important that the ASA quality metrics included breakthrough pain.”

He noted that a 2022 systematic review found that in randomized controlled trials involving elective cesarean deliveries, approximately 15% of patients needed either supplemental analgesia or conversion to general anesthesia. “Some anesthesiologists believe that this prevalence figure is too high, while others argue that it is too low,” he said. “We are now recruiting patients into a multicenter study endorsed by the SOAP [Society for Obstetric Anesthesia and Perinatology] Research Network to explore this topic. In the meantime, we have the OAA [Obstetric Anaesthetists’ Association] new expert consensus opinion on how to manage someone with breakthrough pain. We need to develop U.S.-specific frameworks, protocols and metrics within our institutions based on evidence, and also work is needed to follow up on these patients, who are at increased risk of PTSD [post-traumatic stress disorder].”

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The analgesic efficacy of intravenous dexamethasone for post-caesarean pain: a systematic review with meta-analysis and trial sequential analysis (Eur J Anaesthesiol 2022;39[6]:498-510)

“This has been a controversial area,” Sultan said. “In 2021, the Society for Obstetric Anesthesia and Perinatology published their consensus statement on enhanced recovery after cesarean delivery, stating that ondansetron or dexamethasone or metoclopramide should be given as an antiemetic. In non-obstetric literature, there is pretty good evidence that dexamethasone also has analgesic benefits, prolonging analgesia, but the evidence in obstetrics is not as good.”

This study answers that question, comparing analgesic outcomes in patients undergoing a cesarean delivery with or without dexamethasone afterward. “In a secondary outcome, the time to first analgesia request was prolonged by about 2.5 hours in the dexamethasone-treated group,” he said. “The primary outcome, early pain scores, showed that dexamethasone reduced those scores by 1 out of 10. It’s questionable whether that finding alone is clinically significant, but taken together with the duration of analgesia and reduction in opioid consumption with dexamethasone, this suggests that patients who are not diabetic should receive postpartum dexamethasone. There is still work to be done on timing and dosage, however.”

By Gina Shaw

Farber reported serving on medical advisory boards for HemoSonics and Octapharma, and receiving research support from Flat Medical. Sultan reported no relevant financial disclosures.