Highlights of the 37th Annual Meeting of the Society for Obstetric Anesthesia and Perinatology

May 4-7, 2005, Palm Desert, California

William Camann, MD


June 07, 2005

The 37th Annual Meeting of the Society for Obstetric Anesthesia and Perinatology (SOAP) was held May 4-7, 2005 in Palm Desert, California. This thriving and exciting meeting was attended by nearly 500 participants -- mostly anesthesiologists, obstetricians, and internists. The meeting consisted of presentations of original research, plenary sessions, panel discussions, and clinical updates. This report will feature only a small fraction of the innovative research and relevant updates presented at SOAP, so my apologies in advance to any participant who may have been left out!

The area of obstetric anesthesia research is active and vigorous. At this year's meeting, 151 abstracts were accepted by the scientific program committee for presentation. A sample of the works is presented below.

Dr. Voltaire Misa and colleagues (Wake Forest University School of Medicine, Winston-Salem, North Carolina) compared the reliability of a verbal and visual pain assessment scale in labor and found that a good correlation existed. This is important, as the Joint Commission on Accreditation of Healthcare Organizations has now mandated assessment of pain as the "fifth vital sign." The methods we use to assess pain on the labor floor are varied. This study lends credence to the validity of either visual or verbal rating scales.

Dr. Mrinalini Balki and colleagues (Mt. Sinai Hospital, Toronto, Ontario) examined the oxytocin requirements at cesarean delivery for failure to progress. Previous work by this group has shown that the ED90 of oxytocin at elective cesarean delivery is only 0.3 IU. This small amount is much less than that commonly used in most cesarean deliveries. The current study found the ED90 of oxytocin at cesarean delivery for FTP to be only 3 IU. This is still a small amount, compared with current average usage. Of course, some patients will require more according to their clinical condition; titration to clinical effect is always warranted. Nonetheless, oxytocin is not without side effects, so a smaller dose or a more stringent infusion rate may be of benefit in post-cesarean delivery care.

Dr. Stephen Halpern and colleagues (Sunnybrook Women's College, Toronto) examined a meta-analysis of the effect of concentration of epidural local anesthetic with regard to obstetric outcome. As expected, these investigators found that lower-dose epidurals were associated with a greater likelihood of spontaneous vaginal delivery. This is an important finding, as the trend among virtually all obstetric anesthesiologists today is to use epidural solutions with ever-decreasing amounts of local anesthetic in an effort to decrease motor block during labor. The results of this study support the clinical need for this practice.

Dr. Patricia Lavand'homme and colleagues (Universite Catholique de Louvain, Belgium) examined the risk for development of chronic pain after cesarean delivery. They found that 15% of patients had residual pain and discomfort around the surgical scar at 6 months after delivery. Many clinicians do not consider long-term sequelae of cesarean delivery in their overall care assessments. With a steadily rising cesarean rate, problems such as chronic pain will be seen with greater frequency. All those who care for such patients should be aware of these possible outcomes and be prepared to discuss and manage or appropriately refer such patients for evaluation.

The exciting area of pharmacogenetics has been featured at previous SOAP meetings. This year, work was presented by Drs. Richard Smiley and Ruth Landau (Columbia University, New York, NY, and University of Geneva, Switzerland). Their fascinating work described 2 findings: (1) genetic variants of the beta-2 adrenergic receptor can influence response to vasopressor drugs during treatment of spinal anesthesia-induced hypotension at cesarean delivery, and (2) polymorphisms of the mu-opioid receptor can influence the response to intrathecal fentanyl analgesia during labor. The results are important as clinicians often see individual variability in responsiveness of patients to medications. Perhaps this is not just random scatter but actually related to a genetic basis. It may be that future physicians will use genotypic analysis to predict and choose which drugs, or what doses of drugs, are most effective for certain patients. Exciting prospects indeed!

Morbid obesity is an epidemic in our society today. Dr. Richard Wissler (University of Rochester, New York) presented a systematic review of outcomes of women who became pregnant after bariatric surgery. It was reassuring to note that successful weight loss after bariatric surgery was associated with fewer complications during pregnancy. Patients who have undergone this type of surgery need close surveillance for nutritional deficiencies during pregnancy and lactation.

Every woman wants a pain-free labor, right? However, it's not always that simple. Dr. George McKeen (Halifax, Nova Scotia, Canada) examined influences of analgesic choices among first-time mothers. A variety of sources, including friends, family, physicians, antenatal childbirth classes, and labor and delivery nurses, as well as social and cultural expectations influenced the decision to receive regional analgesia during labor. Of these, friends and family were the most influential. Most women found labor to be more painful than expected. Most women who preferred to avoid an epidural changed their mind during labor. Most women would like to schedule a meeting with an anesthesiologist before labor. These findings have obvious implications for antenatal education and conduct of pain relief techniques during labor.

Several plenary lectures were noteworthy. Dr. James Eisenach (Wake Forest University School of Medicine), in the annual "Fred Hehre Memorial Lecture," discussed new findings in the anatomic and biologic understanding of labor pain. In particular, he discussed the implications for short- and long-term sequelae of labor and post-cesarean pain. These novel approaches may ultimately lead to the development of new modalities of pain management that may (speculative, of course) influence the development of chronic pain syndromes after surgical procedures or childbirth.

Dr. Errol Norwitz, Chief of Maternal-Fetal Medicine at Yale University, delivered the "What's New in Obstetrics" lecture. Topics included fetal surgery (largely disappointing results, with the exception of treatment of twin-twin transfusion syndrome), maternal mortality (getting better in most, but not all, parts of the world), preterm labor (risk factor stratification, lifestyle modification, and treatment of sexually transmitted diseases may be the most important preventive strategies), post-term pregnancies (the risks of post-maturity, although well known, may be even higher than previously considered). Finally, there was discussion (both pro and con) of the emerging concept of the maternal request cesarean delivery.

Dr. Raymond Powrie, Director of the fellowship program in obstetric medicine at Women and Infant's Hospital in Providence, Rhode Island, and current President of the North American Society of Obstetric Medicine (NASOM), delivered a lecture on "What's New in Obstetric Medicine?" One of the questions he addressed is, "Why is there a specialty of obstetric medicine?" This relatively new field is emerging as an important adjunct in the care of obstetric patients. More women are experiencing delayed childbirth (the so-called "mature gravida"); medical care (and survival to adulthood) of women with congenital heart disease is improving and so they are becoming pregnant; and the ever-increasing sophistication and aggressiveness of assisted reproductive technologies means we are seeing an older, sicker population of women who are pregnant. These groups of women present a variety of medical challenges for obstetricians and anesthesiologists as we care for them during pregnancy and in the peripartum period. Obstetric medicine and societies such as NASOM consist mostly of internists who devote the bulk of their practice to the care of medical complications during pregnancy. The availability of an internist, a so-called "obstetric medicine" specialist, is a tremendous addition to the consultative care of these women. All who care for pregnant women will be hearing much more from this valuable group of colleagues in the future.

A panel discussion was held on "International Aspects of Obstetric Anesthesia." Panelists included those who have practiced obstetric anesthesia in Barbados, Brazil, Ghana, Kuwait, and Turkey. A fascinating session ensued as the audience heard some similar themes from the panelists. Obstacles to safe care include obesity, grand multiparity (particularly in Kuwait, where 25% of the cesareans are done on women who have already had 4 or more previous cesareans); lack of education -- and in particular antenatal education; fear of regional anesthesia; outdated equipment; and lack of supplies, ancillary equipment, and personnel.

A debate was held on the safety of the use of the cell salvage device in the management of obstetric hemorrhage. A concern about this technology has always been the possible introduction of elements of amniotic fluid into the maternal circulation, triggering the syndrome known as amniotic fluid embolism (AFE). Two well-known experts in the field of hematology and transfusion medicine had a lively and spirited exchange. Dr. John Waters (University of Pittsburgh) argued that these concerns are not founded on the basis of the existing literature, that clinical experience supports the safe use of re-infusion of salvaged blood in the obstetric setting, and that cell salvage technology may help save lives in these often desperate circumstances. In rebuttal, Dr. Paula Santrach (Mayo Clinic, Minneapolis, Minnesota) argued that the existing blood supply is extraordinarily safe, risk of transfusion-associated infectious disease is trivial, and that we do not know for sure whether the cell salvage washing process truly extracts whatever (at present unknown) substances are responsible for the syndrome of AFE. As the incidence of AFE is rare (roughly 1 per 50,000 births), and only several hundred cases of intraoperative cell-salvage have been reported in the obstetric setting, she argued that numbers are just too small at present to make a determination. Nonetheless, Dr. Santrach did concede that existing cases do suggest that the cell salvage device could be used if one is faced with extraordinary or compelling circumstances precluding the use of banked blood products.

The mission of SOAP is to provide a forum for discussion of medical problems unique to the peripartum period and to promote excellence in medical care, research and education in anesthesia, obstetrics and neonatology. The next meeting will be held April 26-30, 2006, at the Fontainebleau Resort & Spa in Miami, Florida. Further information is available at: www.soap.org .


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