What’s New in Obstetric Anesthesia

The aim of this review is to synthesize key concepts and novel research from the published literature in obstetric anesthesia, obstetric practice, and maternal and perinatal health for the calendar year 2013. These topics were recently addressed in the “What’s New in Obstetric Anesthesia” lecture presented at the 46th Annual Society of Obstetric Anesthesia & Perinatology Meeting in Toronto, Ontario, Canada. This lectureship, which began in 1975, was renamed in 1995 in honor of Dr. Gerald Ostheimer, a master clinician and researcher in the field. Articles were chosen based on their potential to impact future practice and investigation, to highlight obstetric anesthesiologists’ role as peridelivery physicians, and to improve multidisciplinary coordination of care. The review begins with an assessment of the major threats to maternal and fetal safety and well-being, and the anesthesiologist’s role in mitigating them. Current concepts in labor analgesia and intra- and postoperative cesarean delivery anesthesia/analgesia are explored. An annotated bibliography is included as Supplemental Digital Content (https://links.lww.com/AA/B86). MATERNAL OUTCOMES Historically, the U.K. Centre for Maternal and Child Enquiries provided in-depth analyses of maternal deaths from nationally maintained, clinically detailed databases. Using similar methodology, in 2013 a multidisciplinary group of perinatal experts published their analysis of 660 maternal deaths in France, occurring between the years 1998 and 2007.1 Despite an increase in risk factors, such as advanced maternal age, obesity, and cesarean delivery, the reported maternal mortality ratio was stable over the time period, at 8 per 100,000 live births. The “direct” (i.e., pregnancy-related) causes of death were similar to those in the United Kingdom and United States and included hemorrhage (18%), hypertensive disorders of pregnancy (10%), amniotic fluid embolus and thromboembolism (each 10%–12%), early pregnancy death (5.1%), and sepsis (3.0%). Anesthesia-related deaths accounted for 1.8% of the “direct” deaths. Cardiovascular disease was the primary “indirect” cause of maternal death. Over half of the maternal deaths were judged to be potentially avoidable, often due to delay in or inadequate care delivered by obstetric and anesthesia providers. This deficiency was previously reported in several other high-income countries.2–6 In the United States, investigation of severe maternal morbidity and mortality is increasingly accomplished through analyses of large administrative datasets, particularly in the case of rare events.7,8 Using the Medicaid Analytic eXtract dataset (years 2000 to 2007) and a cross validation technique, Bateman et al.9 devised a simple measure to summarize the burden of illness in the obstetric population. This obstetric risk score, which performed better in the obstetric population than previously developed non-obstetric indices, has applications in epidemiologic, health services and comparative effectiveness research. The odds of maternal end-organ injury or death increased for each point increase in the comorbidity risk score (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.35–1.39). Obstetric Hemorrhage Obstetric hemorrhage is the primary cause of maternal death worldwide. A 2013 retrospective review of the Nationwide Inpatient Sample, the largest U.S. inpatient health care utilization dataset representing approximately 20% of all delivery admissions, reported a doubling of the postpartum hemorrhage (PPH) rate (from 1.9 per 1000 deliveries in 1999 to 4.2 per 1000 deliveries in 2008, P value for yearly trend < 0. 0001), with increases in both severe atonic and nonatonic hemorrhage.10 Many of the expected risk factors were present in the affected patients, including advanced maternal age (adjusted OR [aOR], 1.5; 95% CI, 1.5–1.6), multiple pregnancy (aOR, 2.8; 95% CI, 2.6–3.0), uterine fibroids (aOR, 2.0; 95% CI, 1.8–2.2), preeclampsia (aOR, 3.1; 95% CI, 2.9–3.3), chorioamnionitis (aOR, 2.9; 95% CI, 2.5–3.4), placenta previa or abruption (aOR, 7.0; 95% CI, 6.6–7.3), cervical laceration (aOR, 94.0; 95% CI, 87.3–101.2), uterine rupture (aOR, 11.6; 95% CI, 9.7–13.8), instrumented vaginal delivery (aOR, 1.5; 95% CI, 1.4–1.6), and cesarean delivery (aOR, 1.4; 95% CI, 1.3–1.5). However, changes in these risk factors explained only 5.6% of the PPH increase. This administrative dataset lacked the clinical detail necessary to explore other potentially relevant changes in maternal status (e.g., obesity) and obstetric practice (e.g., induction or augmentation of labor). To address the hazards of PPH, obstetric hemorrhage treatment protocols have been developed by multidisciplinary teams around the world. The “New WHO Recommendations on Prevention and Treatment of Postpartum Hemorrhage” were released, outlining the strategic approach in low-income countries.11 Uterotonic drugs, ideally oxytocin, should be used during the third stage of labor, and for intractable PPH. Temporizing measures, including bimanual uterine compression, nonpneumatic antishock garments, and external aortic compression, are indicated until further care is available.11 The European Society of Anaesthesiology’s expert “Guidelines for the Management of Severe Perioperative Bleeding” in obstetric hemorrhage emphasizess the importance of initiating uterotonic therapy, but progressing to mechanical uterine preservation maneuvers (i.e., B-Lynch or compression sutures or interventional radiologic techniques), with escalation to hysterectomy, if needed and feasible.12 The guidelines stressed the use of plasma fibrinogen concentration to predict impending PPH, specifically serum values <2.9 g/L in the setting of a platelet count of 100 × 109 L−1 or less at labor onset, or <2 g/L in a parturient with bleeding, and multidisciplinary planning for known cases of placenta accreta. Data are lacking to guide specific transfusion triggers or hemoglobin concentration targets for acute resuscitation during PPH. However, these experts recommended balanced replacement with red blood cells, fresh frozen plasma, platelet concentrates, and cryoprecipitate, noting that baseline serum fibrinogen concentrations in pregnancy are higher than in the nonpregnant state. Tranexamic acid use should be considered (e.g., for obstetric bleeding, to reduce the duration of bleeding and transfusion needs), although small studies have been unable to assess thrombotic complications and mortality.13 The ongoing international WOMAN (World Maternal Antifibrinolytic) double-blind randomized control trial (RCT) of tranexamic acid administration early in PPH, and its effect on reducing maternal mortality, hysterectomy, and other negative outcomes, will provide more definitive guidance in the future.14 Finally, the successful use of cell salvage techniques was reflected in the guidelines and other 2013 reports, although a single case of hemodynamic collapse in a critically ill patient was described.12,15,16 A hemorrhage management checklist was among the 12 surgical-crisis checklists that Arriaga et al.17 hypothesized would significantly improve adherence to best practices in crisis situations. Key steps in this checklist were requests for help, resuscitation with IV fluids, blood bank notification within 5 minutes of unexpected significant blood loss, and further resuscitation with blood products within the next 5 minutes. Chest compressions should be initiated within 1 minute of onset of ventricular fibrillation. In their RCT of simulated crises with 17 multidisciplinary operating room teams at 3 institutions, these investigators found that using the hemorrhage and other checklists protected against failure to adhere to critical steps (adjusted relative risk [aRR], 0.28; 95% CI, 0.18–0.42; P < 0.001). Ninety-seven percent of participants reported that they desired checklists in real-life events. Hypertensive Disorders of Pregnancy/Preeclampsia Hypertensive disorders of pregnancy were a prominent topic in 2013, featured in high-quality publications in >20 journals. The American College of Obstetricians and Gynecologists (ACOG) Task Force on Hypertension in Pregnancy published a critical review of the literature. Despite productive research in the field, there are still no clinically applicable tests that can be used early in pregnancy to reliably predict the impending development of preeclampsia.18 Given the 25% increase in preeclampsia over the past 2 decades, with its associated considerable morbidity and mortality, the 2002 definition of preeclampsia was modified to promote early recognition and more standardized management of the disease (Table 1).19 Proteinuria was removed as an absolute requirement to avoid delay in preeclampsia diagnosis. The term “mild preeclampsia” was replaced with “preeclampsia without severe features” to reflect the dynamic nature of the disease.Table 1: Diagnostic Criteria for PreeclampsiaA high level of oversight and available resources to treat these mothers and their developing fetuses was deemed imperative. Serial maternal and fetal testing was recommended for women with gestational hypertension or preeclampsia without severe features. Delivery at 37 0/7 weeks’ gestational age was recommended for women with preeclampsia without severe features. In stable patients with severe preeclampsia at <34 0/7 weeks’ gestational age, pregnancy should be continued “only at facilities with adequate maternal and neonatal intensive care resources.” The active ante-, intra- and postpartum management of severe hypertension (i.e., blood pressure ≥160/110 mm Hg) was strongly advocated by the ACOG Task Force, as substandard treatment of high maternal blood pressure in patients with hypertensive disorders of pregnancy has been implicated in many of the 14% of maternal deaths related to stroke.20 A 2013 Cochrane meta-analysis concluded that there is no superior antihypertensive drug; therefore, medication choice should be based on the clinician’s familiarity and experience.21 Nimodipine, diazoxide, ketanserin and magnesium sulfate (as an antihypertensive agent) are best avoided. In an acute hypertensive emergency, oral nifedipine achieved target blood pressure more quickly than IV or minutes minutes P without clinically significant in a small RCT of for the obstetric on to maternal hemodynamic changes during induction of anesthesia in patients was provided by et These investigators that the blood pressure and rate to in patients with severe preeclampsia were using 5 of and of included fetal The of preeclampsia onset was found to be with the of maternal and fetal preeclampsia 0/7 weeks’ gestational was associated with a increased risk of perinatal death or severe neonatal morbidity (aOR, 95% CI, and was more strongly associated with risk factors such as hypertension and with disease (aOR, 2.0; 95% CI, The maternal morbidity associated with hypertensive disorders of pregnancy is more than previously including gestational was associated with increased risk for future maternal and and in a of women with an of years of This for risk factors (e.g., and but for the effect of antihypertensive or postpartum risk Maternal et maternal sepsis in 1 per and found that the odds of the severe with acute or in per and death in 1 per increased by per year in the United States from 1998 to This analysis of Nationwide Inpatient that and are for maternal and each and uterine The were and risk factors for severe sepsis were including advanced maternal age, Medicaid products of rupture of multiple and or a population risk of the is on the obstetric care to be and in impending sepsis in patients to have a more disease and Anesthesia-related maternal mortality has continued to in due to the and successful use of in an obstetric is as the to during a a an rate of 1 per successful in which is approximately that in the in this of and successful in United Kingdom between and there were no maternal deaths. The was used as a in the of the failure of the patients a and of all with clinical The risk of failure was increased a was for the patient without a present 95% CI, P and in patients with advanced maternal age 95% CI, P In there was a increase in the risk of for each 1 increase in the Postpartum particularly in patients, is an cause of maternal that was in a retrospective review of cesarean The was and the was in of the is that the delivery of or with oral or for was associated with or However, and other of were maternal and resuscitation by 5 cesarean delivery is indicated to improve maternal and fetal the in the labor is that the patient to the operating room be (e.g., to and and to To this rare and critical et the effect of simulated patient from the labor to operating room on the of The of delivered compressions (i.e., those with and without was significantly the patient was from the labor room to the operating in the operating room for the group for the P in resuscitation were in all of the group and only of the group < was in the group with the group P compressions are critical to successful these provide for cesarean delivery at the of the studies in 2013 provided potential threats to fetal and the role obstetric and care to them. and Delivery that is a cause of death in 5 years several international for the In their analysis of United with high in and et concluded that indicated cesarean delivery and induction of labor accounted for approximately of the increase in these in the United to their European the United States a higher rate and a of and The a in the rate per was of the by by the of in their in only per this would an of U.S. In a of in were as at risk for weeks’ gestational to women with to and women an increased odds of (aOR, 95% CI, and 95% CI, the management of women with labor or were in 2013. a of with or the of in RCT of women no of with oral nifedipine to in reducing a measure of neonatal severe or perinatal death risk 95% CI, and risk 95% CI, to In a of maternal administration in women with labor was to significantly 95% CI, and a of fetal morbidity severe and 95% CI, in fetuses <34 is value in a of if a is A is recommended for women with rupture of and the choice of have been lacking to guide for the (e.g., less and severe neonatal and (e.g., of and of to high concentrations of The international of of 3 in randomized weeks’ gestational to of to or of to The was an analysis an increase in fetal death in the group 95% CI, P In their and this investigation but that the significant in mortality was found a of the at 2 the of a meta-analysis of these and other relevant they an target between and 95% in these The American College of Obstetricians and Gynecologists has concluded that a indicated delivery at 0/7 weeks’ gestational age are at 37 0/7 to weeks’ gestational age that were previously of fetal or gestational are no of they have a higher risk of neonatal of outcomes, or for delivered at 37 0/7 to weeks’ or 0/7 to weeks’ gestational age (aOR, 1.5; 95% CI, and 95% CI, P value for trend to those that delivered at weeks’ gestational of Delivery delivery 0/7 weeks’ and weeks’ gestational is considered to be superior to cesarean delivery without maternal or fetal causes less uterine rupture or placenta previa or less neonatal and maternal of ACOG that if a patient still a cesarean delivery on be performed of inadequate control during labor, or if multiple are et the of in the between 0/7 and weeks’ gestational age by cesarean delivery by women to cesarean delivery or vaginal delivery with a cesarean only if was deemed to be necessary at the time of were in vaginal maternal fetal maternal or fetal was based on delivery However, of patients randomized to the vaginal delivery group cesarean that cesarean deliveries for these are to In is a used during Using score of a of over women other for severe and the safety of use during pregnancy was were no significantly increased perinatal for major in the (adjusted 95% CI, or for delivery 37 weeks’ gestational age (adjusted 95% CI, there was no increased risk for associated with during the and or associated with The of in to were critically in from the mothers of with mothers of with other and over were factors and during including use and within the 2 their were reported for of The analysis a increase in CI, in for such as maternal age, maternal and other for a of per births. were the were although the risk for was increased in the group (aOR, 2.8; 95% CI, These odds of due to were (aOR, 95% CI, the was the mothers with other the impact of the role of in and the of in these The of detail and the potential for by and are of this which for research. However, the increase in use and during and in in the with and other of analgesia or anesthesia for women should be Despite use of to fetal rate a Cochrane meta-analysis of or that the risk of fetal 95% CI, fetal death 95% was significantly with The neonatal risk was 95% CI, although the clinical of this is cesarean delivery or vaginal delivery was more was used 95% CI, and 95% CI, In a retrospective between and the associated the in neonatal morbidity and mortality with the increase in the use of fetal rate This was by changes in practice, including and the of for gestational age and other for the of labor analgesia was by et they a standardized definition of analgesia failure using the This definition be in clinical practice, and In their review of these investigators found an of analgesia to 1 or more of their analgesia at minutes from the of the or with labor analgesia at with obstetric The failure were associated with by more years of and with the to or of duration of labor, cervical or patient at time of failure The for failure was inadequate analgesia at that patient analgesia and and should be a of obstetric anesthesia with a was to be a for and in a 2013 with and with were the use of the risk of failure to the 95% CI, P < 0.001). 95% CI, P 95% CI, to P < and of 95% CI, to P < In a of in failure rate can be as high as et that the from the to the can be in the or the provided the is during the of use for have been performed by a of to be of this for all techniques will and improve In a RCT with women in a practice et analgesia provided superior labor analgesia to in the group with 2 through the and 5 of the through the The group of the and through a were with analgesia to the the patients but significantly in the 1.9 using a P < 0.001). The stage and delivery labor were there were needed in the there were more specifically maternal and fetal The failure rate was and significantly between in the this that both and analgesia are for labor studies are needed to as of techniques are more to as successful for cesarean deliveries with a of a analgesia delivered by a to a at was to improve maternal a 95% CI, P < and to with or without per 95% CI, to P < in a review of with risk of et the of in to the and patients with analgesia were randomized to a or novel group with 1 to per on The group a in the of P and to the The that the higher have been those patients more delivered in advanced is that the analgesia was associated with a in the duration of the stage of labor, of delivery, or neonatal outcomes, although the was to these of the complications of obstetric A Cochrane review of found the obstetric and and for a meta-analysis to assess the of participants affected by or from a single trial that 1 of 1 IV delivery was the for reducing the of patients with of 95% CI, and a more effect than or oral oral IV or IV However, a RCT that for baseline of is needed to this Delivery Anesthesia and Management An investigation of anesthesia for cesarean delivery of fetuses with to the safety of anesthesia in women with patients with fetuses and on were randomized to anesthesia 8 with or anesthesia for cesarean The a primary measure of the fetal at was significantly between the although the was in the the anesthesia group P were no significant in at 1 and 5 minutes or in the for fetal resuscitation between Given the small and the further investigation is needed to these postpartum is associated with an increased risk of maternal and neonatal investigators to patients at high risk for postpartum and to the et a to predict the of patients with delivery based on patient and postoperative in the The P < with risk for postpartum patients in the of postoperative with to be less and more often single than the of the In a investigation, the used to postoperative was found to the of and the for particularly negative were et this effect in their RCT of women or anesthesia for cesarean were and reported less and other negative of the than patients were less to The of this included the of and the that and were (i.e., that on a from 1 to a score of of to score of of analgesia for cesarean delivery was the of the double-blind RCT of patients by et These investigators reported that to increased the duration of postoperative analgesia minutes minutes P The group less P and there was no negative impact on neonatal fetal or other neonatal However, adequate safety studies for have been In half (i.e., of the was found to provide postoperative cesarean delivery reducing the The between the between the 2 was 95% CI, within the were no significant between in or in and there was less and in the these the use of the in have been as patients were unable to and on their to et provided guidance for the use of for postoperative analgesia as an to which has been in the past several In their retrospective patients cesarean delivery were with patients were no significant in the of complications or to the delivery medication of or for in 2 with at were significantly in a that the of of and of performed and a control The with at and 12 in the group that the duration of with an concentration of in patients similar These studies that be in patients with relative to serum concentrations were in in for delivery the plasma concentrations of the potentially in of the patients within the of these patients were and 3 of or This that with a (e.g., and a that is particularly in these anesthesia can be used to increased and of external for fetal et presented a novel of the that obstetric value to by the potential anesthesia is This analysis in the of successful and the relative of vaginal cesarean was that with anesthesia only increases the of a vaginal delivery but is per to to This review the of published during 2013 at better potentially threats to maternal and fetal safety and the of the anesthesiologists’ peridelivery care. Obstetric have been the investigators in many of the significant in maternal morbidity and mortality, the of practice, and during calendar year 2013. This would to to all the to maternal and fetal health in 2013, of their studies were included in this as have from their for on this and at the the and and the and of of the Society of Obstetric Anesthesia and Perinatology for their This was for the analysis and of this to the of the and the analysis reported in this and the This was

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