Dolores M. McKeen

Maternal and perinatal outcomes with increasing duration of the second stage of labor.

OBJECTIVE: To estimate maternal and perinatal outcomes among women with increasing duration of the second stage of labor. METHODS: A population-based cohort study was conducted among women with low-risk, singleton, vertex, nonanomalous deliveries at or after 37 weeks of gestation between 1988 and 2006. Individual maternal (hemorrhagic, infectious, and traumatic), perinatal (birth depression, infectious, and traumatic), and composite outcomes were evaluated with increasing duration of the second stage. Logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals for all outcomes and to account for confounding variables, including maternal age, prelabor rupture of membranes, augmentation of labor, antibiotics in labor, regional analgesia, gestational age, birth weight, and year of birth. Effect modification caused by method of delivery was considered. RESULTS: From a population of 193,823 women, 121,517 women met inclusion and exclusion criteria, of whom 63,404 (52%) were nulliparous. There was an increase in risk of maternal obstetric trauma, postpartum hemorrhage, puerperal febrile morbidity and composite maternal morbidity, and low 5-minute Apgar score, birth depression, admission to the neonatal intensive care unit, and composite perinatal morbidity among both nulliparous women and multiparous women, with increasing duration of the second stage of labor. Method of delivery only modified the effect of duration of second stage among nulliparous women. CONCLUSION: Risks of both maternal and perinatal adverse outcomes rise with increased duration of the second stage, particularly for duration longer than 3 hours in nulliparous women and longer than 2 hours in multiparous women. LEVEL OF EVIDENCE: II

The Recite Study: A Canadian Prospective, Multicenter Study of the Incidence and Severity of Residual Neuromuscular Blockade

BACKGROUND:Postoperative residual neuromuscular blockade (NMB), defined as a train-of-four (TOF) ratio of <0.9, is an established risk factor for critical postoperative respiratory events and increased morbidity. At present, little is known about the occurrence of residual NMB in Canada. The RECITE (Residual Curarization and its Incidence at Tracheal Extubation) study was a prospective observational study at 8 hospitals in Canada investigating the incidence and severity of residual NMB. METHODS:Adult patients undergoing open or laparoscopic abdominal surgery expected to last <4 hours, ASA physical status I–III, and scheduled for general anesthesia with at least 1 dose of a nondepolarizing neuromuscular blocking agent for endotracheal intubation or maintenance of neuromuscular relaxation were enrolled in the study. Neuromuscular function was assessed using acceleromyography with the TOF-Watch® SX. All reported TOF ratios were normalized to the baseline values. The attending anesthesiologist and all other observers were blinded to the TOF ratio (T4/T1) results. The primary and secondary objectives were to determine the incidence and severity of residual NMB (TOF ratio <0.9) just before tracheal extubation and at arrival at the postanesthesia care unit (PACU). RESULTS:Three hundred and two participants were enrolled. Data were available for 241 patients at tracheal extubation and for 207 patients at PACU arrival. Rocuronium was the NMB agent used in 99% of cases. Neostigmine was used for reversal of NMB in 73.9% and 72.0% of patients with TE and PACU data, respectively. The incidence of residual NMB was 63.5% (95% confidence interval, 57.4%–69.6%) at tracheal extubation and 56.5% (95% confidence interval, 49.8%–63.3%) at arrival at the PACU. In an exploratory analysis, no statistically significant differences were observed in the incidence of residual NMB according to gender, age, body mass index, ASA physical status, type of surgery, or comorbidities (all P > 0.13). CONCLUSIONS:Residual paralysis is common at tracheal extubation and PACU arrival, despite qualitative neuromuscular monitoring and the use of neostigmine. More effective detection and management of NMB is needed to reduce the risks associated with residual NMB.

Up-Down Determination of the 90% Effective Dose of Phenylephrine for the Treatment of Spinal Anesthesia-Induced Hypotension in Parturients Undergoing Cesarean Delivery

INTRODUCTION: Hypotension frequently complicates spinal anesthesia for cesarean delivery, and vasopressors are the mainstay for treatment. The most effective dose of phenylephrine for the treatment of spinal anesthesia-induced hypotension has not been estimated. METHODS: Healthy nonlaboring women undergoing a cesarean delivery were recruited. All women received spinal anesthesia using hyperbaric bupivacaine 12 mg with fentanyl and morphine. Each subject received an IV crystalloid fluid bolus before and at the time of initiation of spinal anesthesia (preload and coload). An up-down sequential allocation method using the biased-coin design was used to estimate the 90% effective dose (ED90) of phenylephrine. The assigned phenylephrine dose was based on the response of the preceding subject. If the systolic blood pressure (SBP) decreased >20% of baseline (i.e., SBP 20%) or to an SBP <90 mm Hg, the assigned dose of phenylephrine was administered. If the SBP returned to within 20% of baseline or ≥90 mm Hg within 1 min, this was considered a success, otherwise it was a failure. The initial dose of phenylephrine was 100 μg. The ED90 with 95% confidence intervals (CIs) was calculated using the maximum likelihood estimation and Firth logistic regression. RESULTS: Sixty-nine subjects were screened to participate, of whom 66 subjects consented. Forty-five of the enrolled subjects experienced spinal anesthesia-induced hypotension and received a blinded dose of phenylephrine. Those subjects who developed hypotension received doses of phenylephrine between 80 and 180 μg. No subjects experienced hypertension. Determined with the maximum likelihood estimation method, the ED90 of phenylephrine was 147 μg (95% CI, 98–222 μg). With Firth regression, the probability of a successful response at 150 μg is 90.5% (95% CI, 66.0%–99.0%). CONCLUSION: In this study, we estimated that the ED90 of phenylephrine required to treat spinal anesthesia-induced hypotension in cesarean delivery is approximately 150 μg.

Antiemetics added to phenylephrine infusion during cesarean delivery: a randomized controlled trial.

OBJECTIVE: To estimate whether the addition of metoclopramide or its combination with ondansetron to a prophylactic phenylephrine infusion provides improved intraoperative nausea and vomiting prophylaxis compared with phenylephrine infusion alone. METHODS: Women scheduled for elective cesarean delivery were randomized to one of three groups: placebo (placebo plus placebo); metoclopramide (metoclopramide 10 mg plus placebo); or combination (metoclopramide 10 mg plus ondansetron 4 mg). The first study drug was administered before spinal placement and the second was administered after cord clamping. Spinal anesthesia was standardized. The primary outcome was intraoperative nausea and vomiting. RESULTS: Three-hundred patients completed the study in two centers. Intraoperative nausea and vomiting occurred in 49%, 31%, and 23% of patients in the placebo, metoclopramide, and combination groups, respectively (P<.001). There was a significant difference between the two centers in exteriorization of the uterus (93% compared with 39%; P<.001) and intraoperative nausea and vomiting rates (47% compared with 20%; P<.001). In a multivariable model adjusting for center, exteriorization of the uterus, age, and hypotension, intraoperative nausea and vomiting were significantly lower in the metoclopramide and combination groups compared with placebo (odds ratio [OR] 2.34, 95% confidence interval [CI] 1.24--4.42; P=.001 and OR 4.06, 95% CI 2.06--7.97; P<.001, respectively). Postoperative nausea and vomiting were reduced with the combination compared with placebo at 2 hours (39% compared with 20%; P<.017), but not at 2–6 hours or at 6–24 hours. CONCLUSION: Metoclopramide with ondansetron reduced intraoperative nausea and vomiting and early postoperative nausea and vomiting compared with placebo. Metoclopramide alone also decreased intraoperative but not postoperative nausea and vomiting. Surgical factors contributed to a significant difference in intraoperative nausea and vomiting between the two centers. CLINICAL TRIAL REGISTRATION: NCT01216410, ClinicalTrials.gov, www.clinicaltrials.gov. LEVEL OF EVIDENCE: I

Hypertensive disorders of pregnancy

PurposeIn this continuing professional development module, we review recent Society of Obstetricians and Gynaecologists of Canada (SOGC) guidelines for the classification and diagnosis of hypertensive disorders of pregnancy (HDP) as well as review the clinical features, laboratory investigations, and outcomes of HDP. We explore the evidence for anesthetic management and prevention of end-organ damage in women with HDP and describe the role and contribution of anesthesiologists as part of a multidisciplinary care team.Principal findingsHypertensive disorders of pregnancy can have variable presentations with clinical signs and symptoms that often do not correlate with the underlying severity and progression of the disease. Failure of timely diagnosis and treatment contributes significantly to adverse maternal (neurologic complications, pulmonary edema, and postpartum hemorrhage) and neonatal (respiratory and neurologic complications and stillbirth) outcomes. In the Canadian context, improvements in medical care have led to better maternal and neonatal outcomes. Timing of delivery is crucial in balancing maternal risks and fetal benefits of ongoing pregnancy. Evidence-based SOGC guidelines regarding diagnosis and management of HDP address many aspects of clinical care relevant to anesthesiologists, who have an important role in the multidisciplinary care team.ConclusionsHypertensive disorders of pregnancy are on the rise worldwide, and this trend is expected to continue. The major contributors to maternal mortality are failure to recognize HDP promptly or to treat the condition adequately. It is essential that anesthesiologists understand the disease process and acquire knowledge of the guidelines governing current obstetrical care in order to provide evidence-based multidisciplinary quality care to these patients. Anesthetic management helps prevent potentially deleterious maternal and fetal outcomes.RésuméObjectifDans ce module de développement professionnel continu, nous examinons la directive récente de la Société des obstétriciens et gynécologues du Canada (SOGC) concernant la classification et le diagnostic des troubles hypertensifs de la grossesse (THG) ainsi que les caractéristiques cliniques, les examens de laboratoire et les issues des THG. Nous examinons les données probantes concernant la prise en charge anesthésique et la prévention des atteintes des organes cibles chez les femmes atteintes de THG et décrivons le rôle et la contribution des anesthésiologistes dans le cadre d’une équipe de soins multidisciplinaire.Constatations principalesLes troubles hypertensifs de la grossesse peuvent se présenter sous différentes formes et les signes et symptômes cliniques n’ont fréquemment pas de corrélation à la gravité et à la progression sous-jacentes de la maladie. Si le diagnostic et le traitement ne sont pas entrepris au moment opportun, ils deviennent des facteurs contribuant significativement aux complications maternelles (complications neurologiques, œdème pulmonaire et hémorragie postpartum) et néonatales (complications respiratoires et neurologiques et mortinaissance). Dans le contexte canadien, les progrès en matière de soins médicaux ont abouti à de meilleures issues maternelles et néonatales. La chronologie de l’accouchement est cruciale pour équilibrer les risques encourus par la mère et les bienfaits, pour le fœtus, de poursuivre la grossesse. La directive clinique de la SOGC concernant le diagnostic et la prise en charge des THG aborde de nombreux aspects des soins cliniques pertinents pour l’anesthésiologiste, lequel joue un rôle important dans l’équipe de soins multidisciplinaire.ConclusionLes THG sont de plus en plus fréquents partout dans le monde, et on s’attend à ce que cette tendance se maintienne. Les facteurs principaux contribuant à la mortalité maternelle sont la reconnaissance tardive des THG et un délai prolongé avant de traiter adéquatement cette condition. Il est essentiel que les anesthésiologistes comprennent le processus de la maladie et soient au courant des directives régissant les soins obstétricaux, afin de procurer des soins multidisciplinaires de qualité et fondés sur des données probantes à ces patientes. La prise en charge anesthésique aide à prévenir des issues maternelles et fœtales potentiellement dévastatrices.

We “can do it” does not mean we “should do it”: obesity, umbilical cord prolapse, and spinal anesthesia in the knee-chest position

described the management of a morbidly obeseparturient with umbilical cord prolapse (UCP) and a stablefetal heart rate (FHR), who was administered spinal anes-thesia in the knee-chest position for urgent Cesareandelivery. While the management was successful, we offercomments and address systematic flaws that may reducethe likelihood for the need to use unorthodox management.While UCP is rare (incidence 0.15–0.2%), unfortu-nately, the need for operative delivery and anesthesiaintervention in the obese obstetric population is notuncommon and should be anticipated. The difficulties ofneuraxial anesthesia in morbidly obese parturients are wellestablished.

Our love-hate relationship with succinylcholine: Is sugammadex any better?

Some years ago, a colleague provided anesthesia care to a healthy young adult male for an emergency open appendectomy. Standard of care at that time was a rapidsequence induction and intubation (RSI). Following denitrogenation, general anesthesia and muscle relaxation were achieved with fentanyl, thiopental, and succinylcholine. While maintaining cricoid pressure, tracheal intubation was successfully achieved using direct laryngoscopy. The appendectomy proceeded uneventfully. As the surgeon was closing the abdominal wound, he requested additional muscle relaxation, and accordingly, a small dose of intravenous succinylcholine (20 mg) was administered. Within one minute, asystole was witnessed on the electrocardiogram monitor and no carotid pulse was detected. Help was summoned and chest compressions were initiated. Cardiac rhythm, carotid pulse, and oxygen saturation quickly returned to normal after the administration of atropine. At the conclusion of the surgery and after tracheal extubation, the patient was taken to the recovery room awake in stable condition. The patient was informed that cardiac arrest had occurred in the operating room. Despite no apparent long-term postoperative sequelae, medicolegal action was pursued. Many meetings with the patient and his legal team subsequently followed, and although the case did not proceed to trial, all involved were left with a bad memory of the ugly side effects of succinylcholine. For decades, we have loved to hate succinylcholine. While most of us love the rapid onset and brief duration of action of succinylcholine at critical moments in airway management, such as RSI, we hate the array of adverse effects it produces—including its potential for cardiac arrest with repeat administration. Hunt and Taveau discovered suxamethonium, the international non-proprietary name for succinylcholine, in 1906, but it was not introduced into clinical practice until the early 1950s. Because of its unique characteristics of rapid onset and short duration of muscle paralysis, succinylcholine enjoyed superiority over other muscle relaxants as the ‘‘gold standard’’ for RSI by clinicians for more than half a century. According to a survey conducted in several European countries and the United States, the most desirable features of succinylcholine reported were rapid onset (88%), short duration (64%), and effective relaxation (61%). The thousands of succinylcholine-related papers published since the 1950s have generated an expansive body of literature, including discoveries extending beyond its immediate effects of muscle relaxation. Indeed, it was research into the genetics of inactivation of succinylcholine by plasma cholinesterase that led to the development of the field of pharmacogenetics in the 1950s. By 1957, succinylcholine had its own subject heading in Index Medicus! Unfortunately, the depolarizing nature of succinylcholine is associated with many serious adverse effects of varying clinical significance, and it is therefore contraindicated in many medical conditions, including hyperkalemia, burns, muscular dystrophy, and malignant hyperthermia. In 1992, the United States (US) Food and Drug Administration (FDA) even issued a warning in the Scoline (suxamethonium chloride; GlaxoSmithKline, USA) package insert after receiving reports of O. Hung, MD (&) D. McKeen, MD Department of Anesthesia, Pain Management and Perioperative Medicine, Queen Elizabeth II Health Sciences Centre, Dalhousie University, 1278 South Park St, Halifax, NS B3H 2Y9, Canada e-mail: hung192@gmail.com

Hyperbaric Versus Isobaric Bupivacaine for Spinal Anesthesia: Systematic Review and Meta-analysis for Adult Patients Undergoing Noncesarean Delivery Surgery

BACKGROUND: It is widely believed that the choice between isobaric bupivacaine and hyperbaric bupivacaine formulations alters the block characteristics for the conduct of surgery under spinal anesthesia. The aim of this study was to systematically review the comparative evidence regarding the effectiveness and safety of the 2 formulations when used for spinal anesthesia for adult noncesarean delivery surgery. METHODS: Key electronic databases were searched for randomized controlled trials, excluding cesarean delivery surgeries under spinal anesthesia, without any language or date restrictions. The primary outcome measure for this review was the failure of spinal anesthesia. Two independent reviewers selected the studies and extracted the data. Results were expressed as relative risk (RR) or mean differences (MDs) with 95% confidence intervals (CIs). RESULTS: Seven hundred fifty-one studies were identified between 1946 and 2016. After screening, there were 16 randomized controlled clinical trials, including 724 participants, that provided data for the meta-analysis. The methodological reporting of most studies was poor, and appropriate judgment of their individual risk of bias elements was not possible. There was no difference between the 2 drugs regarding the need for conversion to general anesthesia (RR, 0.60; 95% CI, 0.08–4.41; P = .62; I2 = 0%), incidence of hypotension (RR, 1.15; 95% CI, 0.69–1.92; P = .58; I2 = 0%), nausea/vomiting (RR, 0.29; 95% CI, 0.06–1.32; P = .11; I2 = 7%), or onset of sensory block (MD = 1.7 minutes; 95% CI, −3.5 to 0.1; P = .07; I2 = 0%). The onset of motor block (MD = 4.6 minutes; 95% CI, 7.5–1.7; P = .002; I2 = 78%) was significantly faster with hyperbaric bupivacaine. Conversely, the duration of motor (MD = 45.2 minutes; 95% CI, 66.3–24.2; P < .001; I2 = 87%) and sensory (MD = 29.4 minutes; 95% CI, 15.5–43.3; P < .001; I2 = 73%) block was longer with isobaric bupivacaine. CONCLUSIONS: Both hyperbaric bupivacaine and isobaric bupivacaine provided effective anesthesia with no difference in the failure rate or adverse effects. The hyperbaric formulation allows for a relatively rapid motor block onset, with shorter duration of motor and sensory block. The isobaric formulation has a slower onset and provides a longer duration of both sensory and motor block. Nevertheless, the small sample size and high heterogeneity involving these outcomes suggest that all the results should be treated with caution.

Anesthetic Management Guided by Transthoracic Echocardiography During Cesarean Delivery Complicated by Hypertrophic Cardiomyopathy.

We describe the management of a parturient woman with hypertrophic cardiomyopathy who developed a symptomatic accelerated idioventricular rhythm who required an urgent cesarean delivery at 32 weeks. Transthoracic echocardiography helped guide anesthetic management, including epidural dosing, fluid management, and phenylephrine infusion rates. This case demonstrates the application of transthoracic echocardiography to guide anesthetic management in a parturient woman at risk for cardiovascular compromise.

Persistent paralysis after spinal anesthesia for cesarean delivery

Anterior spinal artery syndrome has rarely been reported as a cause of permanent neurologic complications after neuraxial anesthesia in obstetric patients. A parturient developed anterior spinal artery syndrome after spinal anesthesia for cesarean delivery. A healthy 32-year-old parturient presented at 41(2/7) weeks for primary elective caesarean delivery for breech presentation. Spinal anesthesia was easily performed with clear cerebrospinal fluid, and block height was T4 at 5 minutes. Intraoperative course was uneventful except for symptomatic bradycardia (37-40 beats per minute) and hypotension (88/44 mm Hg) 4 minutes postspinal anesthesia, treated with ephedrine and atropine. Dense motor block persisted 9 hours after spinal anesthesia, and magnetic resonance imaging of the lumbosacral region was normal, finding no spinal cord compression or lesion. Physical examination revealed deficits consistent with a spinal cord lesion at T6, impacting the anterior spinal cord while sparing the posterior tracts.