Maintenance infusion rate of oxytocin after initial 1-IU bolus for elective Cesarean delivery: a dose-finding study.

PURPOSE: The purpose of our study was to determine the minimum effective dose of oxytocin maintenance infusion required to maintain adequate uterine tone in 90% of patients (ED90) after administration of the initial bolus at elective Cesarean delivery (CD) under spinal anesthesia. METHODS: We conducted a prospective, double-blind dose-finding study with biased coin up-down design. Immediately after delivery, a 1-IU oxytocin bolus was administered, followed by a maintenance infusion. The obstetrician assessed the uterine tone by palpation as satisfactory or unsatisfactory. In case of unsatisfactory response, the dose for the next patient was increased by 2 IU·hr-1. For satisfactory response, the dose for the next patient was either decreased by 2 IU·hr-1 with a probability of 1/9, or remained unchanged. The primary outcome was a satisfactory uterine tone from five minutes after delivery until discharge from postanesthesia care unit. The secondary outcomes were blood loss, need for additional uterotonics, and side effects. RESULTS: We analyzed data for 40 patients. The ED90 of oxytocin maintenance infusion was 4.5 IU·hr-1 (95% confidence interval, 3.3 to 5.5) based on the isotonic regression estimator. The median [interquartile range] blood loss was 861 [553-1,181] mL; 18% received additional uterotonics, and 38% developed hypotension post delivery. CONCLUSION: Based on the results of this dose-finding study, we recommend a maintenance infusion rate of 4.5 IU·hr-1 following an oxytocin bolus of 1 IU for adequate uterine tone in pregnant patients undergoing elective CDs. This infusion rate is four-fold lower than that required without an initial bolus. STUDY REGISTRATION: ClinicalTrials.gov ( NCT04946006 ); first submitted 25 June 2021.

RéSUMé: OBJECTIF: L'objectif de notre étude était de déterminer la dose minimale efficace de perfusion d'entretien d'ocytocine nécessaire pour maintenir un tonus utérin adéquat chez 90 % des personnes parturientes (DE90) après l'administration du bolus initial lors d'une césarienne programmée sous rachianesthésie. MéTHODE: Nous avons réalisé une étude prospective et en double aveugle de détermination de la dose avec une méthodologie de conception biaisée type « up-and down ¼. Immédiatement après l'accouchement, un bolus d'ocytocine de 1 UI a été administré, suivi d'une perfusion d'entretien. L'obstétricien·ne a évalué le tonus utérin par palpation comme satisfaisant ou insatisfaisant. En cas de réponse insatisfaisante, la dose pour la personne suivante a été augmentée de 2 UI·h−1. Lors d'une réponse satisfaisante, la dose pour la personne suivante a été diminuée de 2 UI·h−1 avec une probabilité de 1/9, ou est restée inchangée. Le critère d'évaluation principal était un tonus utérin satisfaisant de cinq minutes après l'accouchement jusqu'à la sortie de la salle de réveil. Les critères d'évaluation secondaires étaient la perte de sang, la nécessité d'utérotoniques supplémentaires et les effets secondaires. RéSULTATS: Nous avons analysé les données de 40 patient·es. La DE90 de perfusion d'entretien d'ocytocine était de 4,5 UI·h−1 (intervalle de confiance à 95 %, 3,3 à 5,5) basé sur l'estimateur de régression isotonique. La perte de sang médiane [écart interquartile] était de 861 [553-1 181] mL; 18 % ont reçu des utérotoniques supplémentaires et 38 % ont développé une hypotension après l'accouchement. CONCLUSION: D'après les résultats de cette étude de détermination de la dose, nous recommandons un débit de perfusion d'entretien de 4,5 UI·h−1 après un bolus d'ocytocine de 1 UI pour un tonus utérin adéquat chez les personnes parturientes bénéficiant d'une césarienne programmée. Ce débit de perfusion est quatre fois inférieur à celui requis sans bolus initial. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov ( NCT04946006 ); première soumission le 25 juin 2021.

Differential sensory block during labour epidural analgesia: a prospective observational study to investigate the relationship of lower and upper sensory block levels to cold, pinprick, and light touch.

PURPOSE: A zone of differential block to cold has been recently documented during labour epidural analgesia, with an upper sensory block level (USBL) and a lower sensory block level (LSBL). We aimed to determine the correlation between USBL and LSBL to cold and pinprick and sensory block level to light touch during labour epidural analgesia. METHODS: We conducted a prospective observational study in patients requesting labour epidural analgesia. We placed an epidural catheter at L2/L3 or L3/L4, followed by a programmed intermittent epidural bolus plus patient-controlled epidural analgesia regimen. We assessed the sensory block levels 140 min after administering the loading dose. The primary outcomes were the USBL and LSBL to cold and pinprick and the sensory block level to light touch. RESULTS: We studied 30 patients. The median [interquartile range (IQR)] USBL and LSBL to ice were T7 [T7-T6] and T9 [T10-T8], respectively. The median [IQR] USBL and LSBL to pinprick were T8 [T10-T6] and T10 [T12-T10], respectively. There was a strong correlation between USBL to ice and pinprick (Spearman correlation coefficient, 0.57) and between LSBL to ice and pinprick (Spearman correlation coefficient, 0.52). There was no significant correlation between sensory block level to light touch and either USBL or LSBL to ice or pinprick. CONCLUSION: We observed two sensory block levels to ice and pinprick. Further studies are required to understand if one modality-cold or pinprick-is superior to the other in assessing sensory block levels in this context. Light touch is unreliable as a modality of sensory block assessment during labour epidural analgesia. TRIAL REGISTRATION: ClinicalTrials.gov (NCT05187962); registered 12 January 2022.

RéSUMé: OBJECTIF: Une zone de bloc différentiel de réaction au froid a récemment été documentée pendant l'analgésie péridurale obstétricale, avec un niveau de bloc sensoriel supérieur (USBL, pour upper sensory block level) et un niveau de bloc sensoriel inférieur (LSBL, pour lower sensory block level). Notre objectif était de déterminer la corrélation entre l'USBL et le LSBL au contact du froid et de la piqûre et le niveau de bloc sensoriel au toucher léger pendant l'analgésie péridurale obstétricale. MéTHODE: Nous avons mené une étude observationnelle prospective chez des patient·es demandant une analgésie péridurale obstétricale. Nous avons placé un cathéter péridural au niveau L2/L3 ou L3/L4, suivi d'une administration programmée de bolus périduraux plus un régime d'analgésie péridurale contrôlée par le/la patient·e. Nous avons évalué les niveaux de bloc sensoriel 140 min après l'administration de la dose de charge. Les critères d'évaluation principaux étaient l'USBL et le LSBL en réaction au froid et à la piqûre d'épingle et le niveau de bloc sensoriel en réaction au toucher léger. RéSULTATS: Nous avons étudié 30 patient·es. Les USBL et LSBL médians [écart interquartile (ÉIQ)] à la glace étaient situés au niveau T7 [T7-T6] et T9 [T10-T8], respectivement. Les USBL et LSBL médians [écart interquartile (ÉIQ)] à la piqûre étaient localisés au niveau T8 [T10­T6] et T10 [T12­T10], respectivement. Il y avait une forte corrélation entre l'USBL à la glace et à la piqûre (coefficient de corrélation de Spearman, 0,57) et entre le LSBL à la glace et à la piqûre (coefficient de corrélation de Spearman, 0,52). Il n'y avait pas de corrélation significative entre le niveau de bloc sensoriel en réaction au toucher léger et l'USBL ou le LSBL en réaction à la glace ou à la piqûre. CONCLUSION: Nous avons observé deux niveaux de bloc sensoriel à la glace et à la piqûre. D'autres études sont nécessaires pour comprendre si une modalité ­ le froid ou la piqûre ­ est supérieure à l'autre pour évaluer les niveaux de bloc sensoriel dans ce contexte. Le toucher léger n'est pas fiable en tant que modalité d'évaluation du bloc sensoriel pendant l'analgésie péridurale obstétricale. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT05187962); enregistré le 12 janvier 2022.

Anesthetic management of patients with class 3 obesity undergoing elective Cesarean delivery: a single-centre historical cohort study.

PURPOSE: The preferred neuraxial anesthetic technique for patients with class 3 obesity undergoing elective Cesarean delivery is still under debate. We aimed to describe the anesthetic technique used in our tertiary institution across body mass index (BMI) groups and different surgical incisions. METHOD: In this historical cohort study, we reviewed medical records of patients with a BMI ≥ 40 kg·m-2 undergoing elective Cesarean delivery between July 2014 and December 2020. We collected data on patient characteristics, anesthetic and surgical technique, and procedural times. For data analysis, we stratified patients by BMI into three different groups: 40.0-49.9 kg·m-2, 50.0-59.9 kg·m-2, and ≥ 60.0 kg·m-2. RESULTS: We included 396 deliveries, distributed as follows: 258 with a BMI 40.0-49.9 kg·m-2, 112 with a BMI 50.0-59.9 kg·m-2, and 26 with a BMI ≥ 60.0 kg·m-2. For patients with a BMI 40.0-49.9 kg·m-2, the anesthetic technique of first choice was predominantly spinal anesthesia (71%), whereas for those with a BMI ≥ 60.0 kg·m-2, spinal anesthesia was never used as the anesthetic of first choice. With regard to the surgical incision, spinal anesthesia was almost exclusively used for patients undergoing Pfannenstiel incision and was rarely used for a higher supra- or infraumbilical transverse or midline incision. The overall incidence of general anesthesia was low (7/396, 1.8%). Anesthetic time, surgical time, and operating room time increased almost twofold in patients with a BMI ≥ 60.0 kg·m-2 compared with those with a BMI of 40.0-49.9 kg·m-2. CONCLUSION: Neuraxial anesthesia was successfully used in approximately 98% of patients with class 3 obesity undergoing elective Cesarean delivery. The choice of regional anesthesia technique varied with increasing BMI and with the planned surgical incision. Procedural times increased with increasing BMI. This information should prove useful for comparing anesthetic choices and outcomes in this challenging population.

RéSUMé: OBJECTIF: La technique d'anesthésie neuraxiale préférée pour les patientes atteintes d'obésité de classe 3 bénéficiant d'un accouchement par césarienne programmée n'a pas encore été déterminée. Nous avons cherché à décrire la technique d'anesthésie utilisée dans notre établissement d'enseignement supérieur à travers les groupes d'indice de masse corporelle (IMC) et les différentes incisions chirurgicales. MéTHODE: Dans cette étude de cohorte historique, nous avons examiné les dossiers médicaux de patientes ayant un IMC ≥ 40 kg·m­2 ayant bénéficié d'un accouchement par césarienne programmée entre juillet 2014 et décembre 2020. Nous avons recueilli des données sur les caractéristiques des patientes, la technique anesthésique et chirurgicale et les délais de procédure. Pour l'analyse des données, nous avons stratifié les patientes par IMC en trois groupes différents, soit : 40,0­49,9 kg·m­2, 50,0­59,9 kg·m­2, et ≥ 60,0 kg·m­2. RéSULTATS: Nous avons inclus 396 accouchements, répartis comme suit : 258 pour un IMC de 40,0 à 49,9 kg·m­2, 112 pour un IMC de 50,0 à 59,9 kg·m­2, et 26 pour un IMC ≥ 60,0 kg·m­2. Pour les patientes ayant un IMC de 40,0 à 49,9 kg·m­2, la technique anesthésique de premier choix était principalement la rachianesthésie (71 %), alors que pour celles dont l'IMC ≥ de 60,0 kg·m­2, la rachianesthésie n'a jamais été utilisée comme modalité anesthésique de premier choix. En ce qui concerne l'incision chirurgicale, la rachianesthésie était presque exclusivement utilisée pour les patientes bénéficiant d'une incision de Pfannenstiel et était rarement utilisée pour une incision transversale ou médiane supra- ou infra-ombilicale supérieure. L'incidence globale d'anesthésie générale était faible (7/396, 1,8 %). Le temps d'anesthésie, le temps chirurgical et le temps passé en salle d'opération ont presque doublé chez les patientes ayant un IMC ≥ 60,0 kg·m­2 par rapport à celles ayant un IMC de 40,0 à 49,9 kg·m­2. CONCLUSION: L'anesthésie neuraxiale a été utilisée avec succès chez environ 98 % des patientes atteintes d'obésité de classe 3 bénéficiant d'un accouchement par césarienne programmée. Le choix de la technique d'anesthésie régionale variait en fonction de l'augmentation de l'IMC et de l'incision chirurgicale prévue. Les temps procéduraux augmentaient avec l'augmentation de l'IMC. Ces informations devraient s'avérer utiles pour comparer les choix et les issues en matière d'anesthésie dans cette population difficile.

Oxytocin at Elective Cesarean Delivery: A Dose-Finding Study in Pregnant People With Twin Pregnancy.

BACKGROUND: Multiple pregnancy is associated with higher risk of uterine atony, postpartum hemorrhage (PPH), blood transfusion, hysterectomy, and death. The optimal dose of oxytocin at cesarean delivery in people with twin pregnancy is unknown. We sought to determine the effective bolus dose of oxytocin required to initiate adequate uterine tone in 90% of people (ED90) with twin pregnancy undergoing elective cesarean delivery. Our hypothesis was that the dose of oxytocin would be higher than 0.5 international units (IU) but lower than 5 IU. METHODS: A double-blind dose-finding study using the biased coin up-down method was undertaken in people with twin pregnancy ≥36 weeks gestational age undergoing elective cesarean delivery under neuraxial anesthesia. Those with additional risk factors for PPH, apart from twin pregnancy, were excluded. Oxytocin was administered as an intravenous bolus over 1 minute on delivery of the second fetus. The first patient received 0.5 IU, and subsequent oxytocin doses were administered according to a sequential allocation scheme. The actual doses administered were 0.5, 1, 2, 3, 4, and 5 IU of oxytocin. The primary outcome was the response defined as the satisfactory uterine tone at 2 minutes after completion of administration of the oxytocin bolus, as assessed by the operating obstetrician. Secondary outcomes included need for rescue uterotonic drugs, adverse effects, and estimated blood loss. The ED90 was estimated using the Dixon-Mood and the isotonic regression methods. RESULTS: Thirty patients were included in study. The estimated ED90 of oxytocin was 4.38 IU (95% confidence interval [CI], 3.68-4.86 IU) and 3.41 IU (95% CI, 2.83-3.98 IU) by the isotonic regression and Dixon-Mood methods, respectively. Seven patients had inadequate tone at the 2-minute evaluation point and required rescue uterotonic drugs. The median (interquartile range [IQR]) estimated blood loss was 1031 mL (732-1462 mL) calculated by the change in 24-hour hematocrit. Incidence of hypotension after oxytocin administration was 27%, nausea 30%, and vomiting 17%. CONCLUSIONS: Our results demonstrated that people with twin pregnancy require a much higher dose of oxytocin than those with singleton pregnancies. We recommended people with twin pregnancies should receive an initial 5 IU bolus over at least 1 minute when undergoing elective cesarean delivery under neuraxial anesthesia.

Changes in sensory block level during a programmed intermittent epidural bolus regimen for labour analgesia: a prospective observational cohort study.

PURPOSE: In the context of a programmed intermittent epidural bolus (PIEB) regimen for labour analgesia, one can identify an upper sensory block level (USBL), defined as the highest dermatome with any altered sensation to cold, and a lower sensory block level (LSBL), defined as the highest dermatome with complete sensory block to cold. This study investigated whether and how these sensory block levels vary within PIEB cycles. METHODS: We enrolled patients requesting epidural analgesia. An epidural catheter was placed at L2/L3 or L3/L4. A test dose of 3 mL of bupivacaine 0.125% with fentanyl 3.3 µg·mL-1 was administered, followed by 12 mL of the same solution as the loading dose. A PIEB plus patient-controlled epidural analgesia (PCEA) regimen was initiated 40 min after the loading dose, with bupivacaine 0.0625% with fentanyl 2 µg·mL-1: PIEB 10 mL, PIEB interval 40 min, PCEA 5 mL, lockout interval 10 min, maximum hourly 30 mL. As per institutional protocol, sensory block levels to ice were assessed 20 min after the loading dose and then hourly. Patients included in the study underwent eight extra assessments: immediately before the second and fourth PIEB and 10, 20, and 30 min after the second and third PIEB. RESULTS: We studied 30 patients. The USBL and LSBL achieved their peak value 100 min after the loading dose. The median [interquartile range] USBL was T8 [T9-T7] and T6 [T7-T4] 20 and 100 min after the loading dose, respectively; LSBL was T10 [T11-T6] and T8 [T9-T6], respectively. There was no significant variation in USBL or LSBL within the PIEB cycle between the second and the third or the third and the fourth PIEB. CONCLUSION: Once peak sensory block levels are established, there is no significant variation in the USBL and LSBL within the PIEB cycles. STUDY REGISTRATION: www. CLINICALTRIALS: gov (NCT04716660); registered 21 January 2021.

RéSUMé: OBJECTIF: Dans le contexte du schéma de bolus périduraux intermittents programmés (PIEB) pour l'analgésie du travail, on peut identifier un niveau de bloc sensoriel haut (USBL) défini comme étant le dermatome le plus haut ayant une quelconque modification de la sensation au froid et un niveau de bloc sensoriel bas (LSBL) défini comme étant le dermatome le plus haut ayant un bloc sensoriel complet au froid. Cette étude a cherché à savoir si et comment ces niveaux de blocs sensoriels varient au cours des cycles de PIEB. MéTHODES: Nous avons recruté des patientes demandant une analgésie péridurale. Un cathéter péridural a été placé au niveau L2/L3 ou au niveau L3/L4. Une dose test de 3 mL de bupivacaïne 0,125% avec fentanyl 3,3 µg·ml−1 était administrée, suivie de 12 mL de la même solution représentant la dose de base. Un protocole de PIEB plus analgésie péridurale contrôlée par la patiente (PCEA) a débuté 40 min après l'administration de la dose de base, comportant de la bupivacaïne 0,0625% et du fentanyl 2 µg·ml−1: PIEB 10 mL; intervalle de PIEB 40 min.; PCEA 5 ml; intervalle de verrouillage 10 min.; maximum par heure 30 mL. Conformément au protocole de l'établissement, les niveaux de bloc sensoriel à la glace ont été évalués 20 min après l'administration de la dose de base, puis toutes les heures. Les patientes incluses dans l'étude ont eu huit évaluations supplémentaires: immédiatement avant le deuxième et le quatrième PIEB et 10, 20 et 30 min après les deuxième et troisième PIEB. RéSULTATS: Nous avons étudié 30 patientes. L'USBL et le LSBL ont atteint leur valeur pic 100 min après l'administration de la dose de base. L'USBL médian [plage interquartile] était T8 [T9­T7] et T6 [T7­T4], respectivement 20 et 100 min après la dose de base; Le LSBL était, respectivement, T10 [T11­T6] et T8 [T9­T6]. Il n'y avait pas de variation significative de l'USBL ou du LSBL dans le cycle de PIEB entre le deuxième et le troisième ou le troisième et le quatrième PIEB. CONCLUSION: Une fois les niveaux maximums de blocs sensoriels établis, il n'y a pas de variation significative dans l'USBL et le LSBL dans les cycles de PIEB. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT04716660); enregistrée le 21 janvier 2021.

Programmed intermittent epidural bolus for labour analgesia: a randomized controlled trial comparing bolus delivery speeds of 125 mL·hr-1 versus 250 mL·hr-1.

PURPOSE: Programmed intermittent epidural bolus (PIEB) provides better analgesia for labour pain than continuous epidural infusion does. Nevertheless, commonly used PIEB regimens are associated with high sensory block. We hypothesized that a PIEB technique with slower bolus delivery speed would produce lower sensory levels. METHODS: We recruited term nulliparous women with singleton pregnancies during the first stage of labour. All participants had an American Society of Anesthesiologists Physical Status score of II-III, had epidural catheters placed at L3/4, and had epidural analgesia maintained with PIEB 10 mL every 40 min using 0.0625% bupivacaine with fentanyl 2 µg·mL-1. Women were randomized to receive PIEB delivered at 250 mL·hr-1 (G250) or 125 mL·hr-1 (G125). The study was completed six hours after the loading dose or at full cervical dilatation, whichever occurred first. The primary outcome was the presence of sensory block to ice ≥ T6 in at least one assessment during the study period (maximum six hours). RESULTS: We analyzed data from 90 women. The proportion of women presenting sensory block ≥ T6 at any time was not different between G125 and G250 groups (60.0% vs 64.4%; difference, -4.4%; 95% confidence interval [CI], -24.5 to 15.6; P = 0.66). The median [interquartile range] highest sensory block level was also not different between G125 and G250 groups (T6 [T7-T5] vs T5 [T7-T5], P = 0.39). Women in the G125 group had a lower incidence of hypotension than women in the G250 group did (11.1% vs 33.3%; difference, -22.2%; 95% CI, -38.8 to -5.67; P = 0.01). Quality of analgesia and patient satisfaction were not different between groups. CONCLUSION: The maintenance of epidural analgesia with a PIEB delivery speed of 125 mL·hr-1 did not produce lower sensory block levels when compared with 250 mL·hr-1. The slower injection speed regimen was associated with lower incidence of hypotension, but this secondary finding warrants confirmation in a future trial. TRIAL REGISTRATION: www.ClinicalTrials.gov (NCT03236298); registered 1 August 2017.

RéSUMé: OBJECTIF: L'administration programmée intermittente de bolus périduraux (PIEB, pour programmed intermittent epidural bolus) fournit une meilleure analgésie pour la douleur du travail que l'analgésie péridurale par perfusion continue. Néanmoins, les régimes de PIEB couramment utilisés sont associés à un bloc sensoriel élevé. Nous avons émis l'hypothèse qu'une technique de PIEB avec une vitesse d'administration plus lente du bolus produirait des niveaux sensoriels inférieurs. MéTHODE: Nous avons recruté des femmes nullipares à terme ayant des grossesses uniques au cours de la première étape du travail obstétrical. Toutes les participantes avaient un score de statut physique II-III de l'American Society of Anesthesiologists, des cathéters périduraux placés au niveau L3/4 et une analgésie péridurale maintenue avec des PIEB de 10 mL de bupivacaïne 0,0625 % et de 2 µg·mL-1 de fentanyl, administrés toutes les 40 minutes. Les femmes ont été randomisées à recevoir des PIEB administrés à une vitesse de 250 mL·h-1 (G250) ou 125 mL·h-1 (G125). L'étude se terminait six heures après la dose de charge ou lors de la dilatation cervicale complète, selon la première éventualité. Le critère d'évaluation principal était la présence d'un bloc sensoriel à la glace ≥ T6 lors d'au moins une évaluation au cours de la période à l'étude (pour un maximum de six heures). RéSULTATS: Nous avons analysé les données de 90 femmes. La proportion de femmes présentant un bloc sensoriel ≥ T6 à tout moment n'était pas différente entre les groupes G125 et G250 (60,0 % vs 64,4 %; différence, -4,4 %; intervalle de confiance [IC] à 95 %, -24,5 à 15,6; P = 0,66). Le niveau médian [écart interquartile] le plus élevé de bloc sensoriel n'était pas non plus différent entre les groupes G125 et G250 (T6 [T7-T5] vs T5 [T7-T5], P = 0,39). Les femmes du groupe G125 avaient une incidence d'hypotension plus faible que les femmes du groupe G250 (11,1 % vs 33,3 %; différence, -22,2 %; IC 95 %, -38,8 à -5,67; P = 0,01). La qualité de l'analgésie et la satisfaction des patientes n'étaient pas différentes d'un groupe à l'autre. CONCLUSION: Le maintien de l'analgésie péridurale avec une vitesse d'administration des PIEB de 125 mL·h-1 n'a pas entraîné de taux de blocs sensoriels inférieurs par rapport à une vitesse de 250 mL·h-1. Le régime de vitesse d'injection plus lente a été associé à une incidence plus faible d'hypotension, mais cette constatation secondaire mérite d'être confirmée dans une étude future. ENREGISTREMENT DE L'éTUDE: www.ClinicalTrials.gov (NCT03236298); enregistrée le 1er août 2017.

Carbetocin versus oxytocin following vaginal and Cesarean delivery: a before-after study.

PURPOSE: A nationwide shortage of oxytocin in Canada resulted in a temporary switch from oxytocin to carbetocin for all postpartum women at our institution. This change offered a unique opportunity to conduct a pragmatic comparative assessment of the efficacy of carbetocin and oxytocin. METHODS: In a retrospective before-after study, we reviewed the medical records from 641 women in the carbetocin group and 752 women in the oxytocin group . The standard carbetocin dosing was 100 µg iv following vaginal and intrapartum Cesarean delivery, while for elective Cesarean delivery it was 50 µg, with an additional 50 µg if required. The standard oxytocin dosing was 5 IU iv followed by 2.4 IU·hr-1 for four to six hours after vaginal delivery, while for Cesarean delivery it was 1-3 IU iv, three minutes apart, up to 10 IU if required, followed by the same maintenance. In both modalities of delivery, if uterine tone was suboptimal, the maintenance dose of oxytocin could be increased to 4.8 IU·hr-1. In both groups, additional uterotonics were used as required. The primary outcome was the need for additional uterotonics. Secondary outcomes included estimated and calculated blood loss, the occurrence of postpartum hemorrhage, and the need for blood transfusion. RESULTS: The incidence of additional uterotonic use was not different between the carbetocin and oxytocin groups (12.0% vs 8.8%; P = 0.05; odds ratio, 1.39; 95% confidence interval, 0.97 to 2.00). The incidence of postpartum hemorrhage was higher in the carbetocin group than in the oxytocin group (10.3% vs 6.6%; P = 0.01). Blood transfusion was more common in the carbetocin group (1.4% vs 0.3%; P = 0.02). CONCLUSION: There was no difference in the use of additional uterotonics when carbetocin or oxytocin were used in a cohort of women undergoing vaginal deliveries and both elective and emergency Cesarean deliveries.

RéSUMé: OBJECTIF: Une pénurie nationale d'ocytocine au Canada a entraîné l'utilisation temporaire de la carbétocine en remplacement de l'ocytocine pour toutes les femmes en post-partum dans notre établissement. Grâce à cette substitution, nous avons bénéficié d'une occasion unique de mener une évaluation comparative pragmatique de l'efficacité de la carbétocine et de l'ocytocine. MéTHODE: Dans une étude rétrospective avant-après, nous avons examiné les dossiers médicaux de 641 femmes dans le groupe carbétocine et de 752 femmes dans le groupe ocytocine. Le dosage standard de carbécotine était de 100 µg iv après un accouchement vaginal et pendant un accouchement par césarienne intrapartum, tandis que pour un accouchement par césarienne élective, le dosage était de 50 µg, avec 50 µg supplémentaires au besoin. Le dosage standard d'ocytocine était de 5 UI iv suivi de 2,4 UI·h-1 pendant quatre à six heures après un accouchement vaginal, tandis que pour un accouchement par césarienne, il était de 1 à 3 UI iv, à trois minutes d'intervalle, jusqu'à 10 UI au besoin, suivi du même dosage d'entretien. Dans les deux types d'accouchement, si le tonus utérin était sous-optimal, la dose d'entretien d'ocytocine pouvait être augmentée à 4,8 UI·h-1. Dans les deux groupes, des utérotoniques supplémentaires ont été utilisés au besoin. Le critère d'évaluation principal était le besoin d'utérotoniques supplémentaires. Les critères d'évaluation secondaires comprenaient la perte de sang estimée et calculée, la survenue d'une hémorragie du post-partum et la nécessité d'une transfusion sanguine. RéSULTATS: L'incidence d'utilisation d'utérotoniques supplémentaires n'était pas différente entre les groupes carbétocine et ocytocine (12,0 % vs 8,8 %; P = 0,05; rapport de cotes,1,39; intervalle de confiance à 95 %, 0,97 à 2,00). L'incidence d'hémorragie du post-partum était plus élevée dans le groupe carbétocine que dans le groupe ocytocine (10,3 % vs 6,6 %; P = 0,01). Les transfusions sanguines étaient plus fréquentes dans le groupe carbétocine (1,4 % vs 0,3 %; P = 0,02). CONCLUSION: Aucune différence dans l'utilisation d'utérotoniques supplémentaires n'a été observée lors de l'utilisation de carbétocine ou d'ocytocine dans une cohorte de femmes accouchant par voie vaginale ou par césarienne élective ou en urgence.

Feasibility of ultrasound-assisted lumbar punctures performed by pediatric oncologists at the point of care.

BACKGROUND: Ultrasound assistance improves success rates and reduces adverse outcomes of lumbar punctures (LPs) among adult patients in the emergency room and the operating room, but has not been evaluated in pediatric patients with cancer. Our objectives were (1) to determine whether pediatric oncologists could perform ultrasound-assisted LPs following a structured teaching curriculum, and (2) to determine the feasibility of recruiting pediatric cancer patients to a clinical trial of this procedure. METHODS: Three pediatric oncologists completed a curriculum composed of didactic teaching followed by hands-on workshops. Each learner was evaluated during 20 attempts at three ultrasound tasks using the cumulative sum method. The three pediatric oncologists then performed ultrasound assessments prior to routinely scheduled LPs. Feasibility was defined as ability to perform at least 30 ultrasound-assisted LPs within 6 months. Secondary outcomes were the proportion of successful, bloody, or traumatic LPs, time required, and perceived helpfulness of ultrasound. RESULTS: All three pediatric oncologists achieved competence in the three tasks of ultrasound scanning within 20 evaluated attempts. We recruited 62 patients within 1 month, and 58 underwent an ultrasound-assisted LP. All LPs were successful. Two LPs (4%) had ≥500 red blood cells (RBCs)/µl, and nine (16%) had ≥10 RBCs/µl. Median time to conduct the scan was 1.9 minutes (range 0.8-4.0 minutes). In 37 (64%) of the LPs, ultrasound assistance was considered helpful or very helpful. CONCLUSIONS: Pediatric oncologists readily achieved competence in ultrasound-assisted LPs, and ultrasound was commonly perceived as helpful. It is feasible to proceed to a randomized trial of this procedure in pediatric cancer.

The Effects of Nitroglycerin on the Oxytocin Dose-Response Profile in Oxytocin-Desensitized and Naïve Human Myometrium: An In Vitro Study.

BACKGROUND: Nitroglycerin is used for acute reduction in uterine tone. Prolonged oxytocin exposure causes desensitization of oxytocin receptors. It is unknown if nitroglycerin exposure impacts the subsequent action of oxytocin in the setting of oxytocin receptor desensitization. This study investigated the effects of nitroglycerin on oxytocin-desensitized and oxytocin-naïve human myometrium and the subsequent response to oxytocin dose-response testing in vitro. METHODS: Myometrial samples from 17 elective cesarean deliveries were divided into strips and allocated to 1 of 4 groups: (1) oxytocin desensitized and no nitroglycerin; (2) oxytocin desensitized and nitroglycerin; (3) oxytocin naïve and nitroglycerin; and (4) oxytocin naïve and no nitroglycerin. Final analysis included 28 strips per group. Nitroglycerin groups were exposed to incremental concentrations of nitroglycerin, while no nitroglycerin groups were kept in control (physiological salt) solution. All groups then underwent oxytocin dose-response testing. Primary outcome was motility index (amplitude × frequency; grams × contractions per 10 minutes [g·c/10 min]). Secondary outcomes were amplitude (g), frequency (contractions/10 minutes), and area under the curve (g·s). All outcomes (nitroglycerin and oxytocin dose-response periods) were expressed as a percentage change from baseline. Values were log transformed, compared using regression modeling and reported as the ratio of 2 geometric means (relative difference). RESULTS: No significant difference was observed in motility index following nitroglycerin administration in oxytocin-desensitized versus oxytocin-naïve groups (relative difference = 19.0%; 95% confidence interval [CI], -32.6 to 109.9; P = .55). On oxytocin dose-response testing, motility index was highest in oxytocin-naïve and no nitroglycerin samples (group 4) (1.356 g·c/10 minutes) followed by oxytocin-naïve and nitroglycerin (group 3) (0.882 g·c/10 minutes), oxytocin-desensitized and no nitroglycerin (group 1) (0.769 g·c/10 minutes), and oxytocin-desensitized and nitroglycerin (group 2) (0.651 g·c/10 minutes) samples. Motility index was significantly reduced in group 1 vs 4 (relative difference = -43.3%; 95% CI, -66.5 to -4.1; P = .034) and group 2 vs 4 (relative difference = -52.0%; 95% CI, -70.9 to -20.8; P = .004). While in groups 3 vs 4, both amplitude (relative difference = -17.8%; 95% CI, -30.9 to -2.2; P = .27) and area under the curve (AUC; relative difference = -17.5%; 95% CI, -30.7 to -1.8; P = .030) were reduced. CONCLUSIONS: Nitroglycerin-induced relaxation was not different between oxytocin-desensitized and oxytocin-naïve human myometrial strips in vitro. However, oxytocin-induced contractility was attenuated after nitroglycerin exposure in both oxytocin-desensitized and oxytocin-naïve samples, with maximum attenuation observed in desensitized tissues. This finding warrants further clinical studies to explore uterine responsiveness to oxytocin in women with oxytocin-augmented labors after nitroglycerin administration.

Predicting pain after Cesarean delivery: pressure algometry, temporal summation, three-item questionnaire.

PURPOSE: Approximately one in five women will experience severe postoperative pain after Cesarean delivery (CD). Previously, a bedside three-item questionnaire (3-IQ) has shown to predict women experiencing higher evoked pain intensity after CD, with an area under the receiver operator characteristics (ROC) curve of 0.72. We hypothesized that the addition of psychophysical pain tests to the existing 3-IQ would improve the ability to predict severe pain in women undergoing elective CD under spinal anesthesia METHODS: This was a prospective cohort study on women undergoing elective CD under spinal anesthesia. Women were assessed preoperatively using the 3-IQ, pressure algometry (PA) and mechanical temporal summation (TS) response. All women received standard perioperative care, including a multimodal analgesia regimen that included intrathecal fentanyl and morphine. A 0-100 mm visual analogue scale (VAS) was used to assess the severity of pain at rest (VASr) and on movement (VASm) at 24 and 48 hr after surgery. Patient satisfaction and opioid consumption were also recorded. We performed ROC curve analyses to assess whether we could improve the ability to predict our primary outcome of severe pain on movement at 24 hr (VASm24 ≥ 70). RESULTS: We studied 195 women. Median [interquartile range] VASm24 was 53 [32-72] and 28% of patients experienced a VASm24 ≥ 70. The ability to predict a VASm24 ≥ 70 assessed by the area under the ROC curve was 0.64 using the 3-IQ and 0.67 using the 3-IQ combined with TS and PA. CONCLUSION: The addition of PA and TS to the 3-IQ model resulted in a predictive model that performed similarly to the 3-IQ model alone. Further research is warranted in this area to better predict women at risk of severe pain post CD.

RéSUMé: OBJECTIF: Environ une femme sur cinq souffrira de douleur postopératoire sévère après un accouchement par césarienne. Un questionnaire à trois critères (Q3C) administré au chevet de la patiente a déjà été utilisé pour prédire quelles femmes éprouveraient une intensité de douleur évoquée plus élevée après une césarienne, avec une aire sous la courbe ROC de 0,72. Nous avons émis l'hypothèse que l'ajout de tests psychophysiques de douleur au Q3C existant améliorerait notre capacité à prédire la douleur sévère chez les femmes bénéficiant d'une césarienne élective sous rachianesthésie. MéTHODE: Il s'agissait d'une étude de cohorte prospective auprès de femmes bénéficiant d'une césarienne élective sous rachianesthésie. Les femmes ont été évaluées en préopératoire à l'aide du Q3C, de l'algométrie par pression (AP) et de la réponse à une sommation temporale (ST) mécanique. Toutes les femmes ont bénéficié des soins périopératoires standard, ainsi que d'un régime d'analgésie multimodal incluant fentanyl et morphine intrathécaux. Une échelle visuelle analogique (EVA) de 0 à 100 mm a été utilisée pour évaluer la sévérité de la douleur au repos (EVAr) et en mouvement (EVAm) à 24 et 48 heures après la chirurgie. La satisfaction des patientes et la consommation d'opioïdes ont également été enregistrées. Nous avons effectué des analyses de la courbe ROC pour déterminer s'il nous était possible d'améliorer notre capacité à prédire notre critère d'évaluation principal, soit la douleur sévère à la mobilisation à 24 heures (EVAm24 ≥ 70). RéSULTATS: Nous avons étudié 195 femmes. L'EVAm 24 médiane [écart interquartile] était de 53 [32-72] et 28 % des patientes ont noté un score sur l'EVAm24 ≥ 70. La capacité à prédire un score sur l'EVAm24 ≥ 70 tel qu'évalué par la surface sous la courbe ROC était de 0,64 en utilisant le Q3C et de 0,67 en utilisant le Q3C combiné à la ST et l'AP. CONCLUSION: L'ajout de l'AP et de la ST au modèle de Q3C a résulté en un modèle prédictif présentant une performance similaire au modèle de Q3C seul. D'autres recherches sont nécessaires dans ce domaine pour mieux prédire les femmes à risque de douleur sévères après une césarienne.

Programmed intermittent epidural bolus for labour analgesia during first stage of labour: a sequential allocation trial to determine the effective interval time between boluses of a fixed volume of 2.5 mL of bupivacaine 0.25% plus fentanyl 8 µg·mL-1.

PURPOSE: We studied the programmed intermittent epidural bolus (PIEB) time interval between boluses of 2.5 mL of bupivacaine 0.25% with fentanyl 8 µg·mL-1 to produce effective analgesia in 90% of women (EI90) during the first stage of labour. METHODS: In a double-blind sequential allocation trial using a biased coin up-and-down design to determine the EI90, the PIEB boluses of 2.5 mL of 0.25% bupivacaine plus fentanyl 8 µg·mL-1 were delivered at varying intervals-60, 50, 40, and 30 min. The primary outcome was the adequate response of the patient to the PIEB regimen, defined as no use of supplemental analgesia for six hours or until the first stage of labour was completed, whichever came first. The secondary outcomes were the upper sensory block level to ice, motor block and hypotension. The isotonic regression with extrapolation approach was used to estimate the EI90. RESULTS: In the 20 women studied, the estimated EI90 was 20 (95% CI, 5.9 to 28.8) min. For the secondary outcomes, we classified women into those assigned to 30 min (16 women) and those assigned to more than 30 min (four women). The median upper sensory block for women in the 30-min group and more than 30 min were T6 (or T5) and T7, respectively. No participants experienced motor block. Hypotension occurred in one patient in the 30-min group. CONCLUSION: The estimated EI90 for boluses of 2.5 mL of bupivacaine 0.25% with fentanyl 8 µg·mL-1 was 20 (95% CI, 5.9 to 28.8) min. These results suggest that there is no advantage in using this regimen compared with those reported in the literature using the same dose of bupivacaine in concentrations of 0.0625% and 0.125%. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT03735771); registered 7 November 2018.

RéSUMé: OBJECTIF: Nous avons étudié l'intervalle de temps d'administration programmée de bolus périduraux (PIEB) entre des bolus de 2,5 mL de bupivacaïne 0,25 % avec 8 µg·mL−1 de fentanyl nécessaire pour procurer une analgésie efficace chez 90 % des femmes (IE90) au cours du premier stade du travail obstétrical. MéTHODE: Dans une étude de répartition séquentielle à double insu utilisant une méthodologie de tirage au sort biaisé de haut en bas pour déterminer l'IE90, des bolus PIEB de 2,5 mL de bupivacaïne 0,25 % plus 8 µg·mL−1 fentanyl ont été administrés à des intervalles variables ­ 60, 50, 40 et 30 min. Le critère d'évaluation principal était une réponse adéquate de la patiente au régime de PIEB, définie comme aucun recours à une analgésie supplémentaire pendant six heures ou jusqu'à la fin du premier stade du travail, à la première condition obtenue. Les critères d'évaluation secondaires comportaient le niveau du bloc sensitif supérieur tel qu'établi par un test de glace, ainsi que la présence d'un bloc moteur et d'hypotension. Nous avons utilisé une méthode de régression isotonique avec une approche d'extrapolation pour estimer l'IE90. RéSULTATS: Chez les 20 femmes étudiées, l'IE90 estimé était de 20 (IC 95 %, 5,9 à 28,8) min. En ce qui touche aux critères d'évaluation secondaires, nous avons catégorisé les femmes selon qu'elles étaient assignées à recevoir un bolus aux 30 min (16 femmes) ou à des intervalles de plus de 30 min (quatre femmes). Le niveau du bloc sensitif supérieur médian pour les femmes dans le groupe 30 min et plus de 30 min se situait à T6 (ou T5) et T7, respectivement. Aucune participante n'a subi de bloc moteur. Une patiente dans le groupe à 30 min a subi un épisode d'hypotension. CONCLUSION: L'IE90 estimé pour les bolus de 2,5 mL de bupivacaïne 0,25 % avec 8 µg·mL−1 de fentanyl était de 20 (IC 95 %, 5,9 à 28,8) min. Ces résultats suggèrent qu'il n'y a aucun avantage à utiliser ce régime posologique plutôt que ceux rapportés dans la littérature utilisant une même dose de bupivacaïne à des concentrations de 0,0625 % et 0,125 %. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT03735771); enregistrée le 7 novembre 2018.

Fetal Surgery for Open Spina Bifida in Canada: Initial Results.

OBJECTIVE: Fetal myelomeningocele closure results in better infant outcomes than postnatal closure at the cost of potential prematurity and maternal morbidity. Our aim is to describe the setup of a fetal myelomeningocele closure program in Canada and document its outcomes. METHODS: We conducted a retrospective review of all open fetal myelomeningocele closure surgeries performed at the Ontario Fetal Centre in its first 3 years of operation (2017-2020). Maternal and fetal baseline characteristics, surgical details, pregnancy outcomes, and infant follow-up until 1 year of age were recorded. RESULTS: Twenty-seven women underwent fetal myelomeningocele closure surgery, 10 of whom (37%) resided outside of Ontario. Mean gestational age at surgery was 25.0 ± 0.7 weeks. All surgeries were technically uncomplicated and no fetal deaths occurred. There was a significant negative correlation between increasing experience and skin-to-skin surgical time (R²â€¯= 0.36; P = 0.001). Of the 26 patients who have delivered, 4 (15.4%) experienced preterm prelabour rupture of membranes. Mean gestational age at delivery was 34.9±3.0 weeks. All but 1 patient delivered by cesarean. Maternal complications occurred in 9 women (34.6%). There were no maternal deaths, but 3 (11.5%) infant deaths. Of the 14 surviving infants who have reached at least 1 year of age, 5 (35.7%) underwent ventriculo-peritoneal shunting. Of the 9 infants who have not yet reached 1 year of age, 3 (33.3%) underwent endoscopic third ventriculostomy and none underwent shunting. CONCLUSION: Fetal open spina bifida closure can be performed in Canada, with results similar to those reported by other international expert centres. Long-term follow-up is ongoing.

Fetal spina bifida: What we tell the parents.

Worldwide, about 150 000 infants are born with spina bifida yearly, making this condition one of the most common fetal central nervous system anomalies compatible with life. Over the last decade, major changes have been introduced in the prenatal diagnosis and management of spina bifida. In this review, we provide a brief summary of the current management of fetal spina bifida and present essential information that should be provided to expecting parents when their fetus has been diagnosed with spina bifida. This information is focused around common parental questions, as encountered in our typical clinical practice, to facilitate knowledge translation.

The effect of morbid obesity or advanced maternal age on oxytocin-induced myometrial contractions: an in vitro study.

PURPOSE: The purpose of this study was to investigate myometrial contractility induced by oxytocin in women with advanced maternal age (AMA) and morbid obesity (MO). We hypothesized that both oxytocin-pretreated and oxytocin-naïve myometrial tissues from women of AMA and women who are MO would exhibit poor myometrial contractility compared with women that are younger and of normal body mass index (BMI). METHODS: This prospective in vitro study was conducted using myometrial samples obtained from women undergoing elective Cesarean deliveries. Three groups of patient were studied: control (≤ 35 yr; BMI, 20-24.9 kg·m-2), AMA (≥ 40 yr; BMI, 20-24.9 kg·m-2), and MO (≤ 35 yr BMI, ≥ 40 kg·m-2). Each myometrial strip was either pretreated with oxytocin 10-5 M or left in physiologic salt solution for two hours. This was followed by a dose-response testing to oxytocin (10-10 M to 10-5 M), during which contractile parameters were measured. The primary outcome was motility index (MI, amplitude × frequency) of contractions. RESULTS: The MI of contractions was reduced in oxytocin-pretreated samples when compared with their oxytocin naïve counterparts in control (estimated difference -69%; 95% confidence interval [CI], -82 to -48; P < 0.001) and AMA groups (estimated difference, -44%; 95% CI, -68 to -2; P = 0.07). The MI of contractions was not different between oxytocin naïve and oxytocin-pretreated samples from MO women (estimated difference, -26%; 95% CI, -63 to 49; P = 0.46); however, it was significantly lower in these groups compared with oxytocin-naïve samples from the control group. CONCLUSIONS: Oxytocin pre-treatment reduced myometrial contractility in AMA and control group women compared with their oxytocin-naïve counterparts, as a function of the desensitization phenomenon. Attenuated oxytocin-induced myometrial contractility in MO women in both oxytocin-pretreated and oxytocin-naïve samples suggests that these women have intrinsically reduced uterine contractile ability. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT01865669; registered 28 May, 2013).

RéSUMé: OBJECTIF: L'objectif de cette recherche était d'étudier la contractilité myométriale induite par l'oxytocine chez des femmes d'âge maternel avancé (AMA) et ayant une obésité morbide (OM). Nous avons formulé l'hypothèse que les tissus de myomètre prétraités avec de l'oxytocine ainsi que les tissus naïfs d'oxytocine provenant de femmes d'AMA ou ayant une OM présenteraient une mauvaise contractilité comparativement à des femmes plus jeunes et à l'indice de masse corporelle (IMC) normal. MéTHODES: Cette étude prospective in vitro a été menée en utilisant des échantillons de myomètre prélevés sur des femmes accouchant par césarienne planifiée. Trois groupes de patientes ont été étudiés : contrôles (≤ 35 ans; IMC, 20 à 24,9 kg·m−2), AMA (≥ 40 ans; IMC, 20 à 24,9 kg·m−2) et OM (≤ 35 ans IMC, ≥ 40 kg·m−2). Chaque bandelette de myomètre a été prétraitée avec de l'oxytocine 10−5 M ou laissée dans une solution salée physiologique pendant deux heures. Cela a été suivi de tests de réponse à des doses croissantes d'oxytocine (10−10 M à 10−5 M) au cours desquels les paramètres contractiles ont été mesurés. Le critère d'évaluation principal était l'indice de motilité (IM, amplitude × fréquence) des contractions. RéSULTATS: Cet IM des contractions était diminué dans les échantillons prétraités avec l'oxytocine, comparativement à leurs équivalents naïfs d'oxytocine dans les groupes contrôles (différence estimée -69 %; intervalle de confiance [IC] à 95 % : -82 à -48; P < 0,001) et AMA (différence estimée, -44 %; IC à 95 %, -68 à -2; P = 0,07). L'IM des contractions n'était pas différent entre les échantillons naïfs d'oxytocine et les échantillons prétraités provenant de femmes ayant une OM (différence estimée, -26 %; IC à 95 %, -63 à 49; P = 0,46). Il était cependant significativement plus faible dans ces groupes comparativement aux échantillons naïfs pour l'oxytocine provenant du groupe contrôle. CONCLUSIONS: Le prétraitement à l'oxytocine a réduit la contractilité myométriale des femmes des groupes AMA et contrôle comparativement à celle des prélèvements naïfs d'oxytocine en fonction d'un phénomène de désensibilisation. L'atténuation de la contractilité myométriale induite par l'oxytocine dans les échantillons prétraités et naïfs d'oxytocine chez les femmes présentant une OM suggère que ces dernières présentent une capacité contractile intrinsèquement réduite de l'utérus. ENREGISTREMENT DE L'ESSAI CLINIQUE: www.clinicaltrials.gov (NCT01865669; enregistré le 28 mai 2013).

The Effect of Intermittent Oxytocin Pretreatment on Oxytocin-Induced Contractility of Human Myometrium In Vitro.

BACKGROUND: Prolonged continuous oxytocin administration during labor may induce oxytocin receptor desensitization, which attenuates the response of the myometrium to further oxytocin, increasing the risk of postpartum hemorrhage. The literature comparing pulsatile (intermittent) versus continuous oxytocin administration for induction and augmentation of labor is inconsistent with regard to maternal outcomes. We aimed to determine the effect of intermittent versus continuous oxytocin preexposure on myometrial responsiveness to subsequent oxytocin. We hypothesized that intermittent oxytocin pretreatment would result in superior subsequent oxytocin-induced contractility than continuous oxytocin pretreatment. METHODS: This in vitro study was undertaken using myometrium obtained from women undergoing elective cesarean deliveries. Each myometrial strip was mounted in an individual organ bath with physiological salt solution under homeostatic conditions and allocated to one of 3 groups: (1) control (no pretreatment); (2) continuous (pretreatment with oxytocin 10(-5) M for 2 hours); or (3) intermittent (pretreatment with alternating oxytocin 10 M and physiological salt solution every 15 minutes, for 2 hours). After pretreatment, dose-response testing to oxytocin 10(-5) to 10(-5) M was performed and contractile parameters were measured. The primary outcome was motility index (MI, amplitude × frequency) of contractions. RESULTS: Eighteen women were recruited, and 86 successful experiments were performed (control n = 29, continuous n = 28, intermittent n = 29). The means (standard errors) of MI (√g·contractions/10 min) in the control, continuous, and intermittent groups were 2.34 (0.09), 1.78 (0.09), and 2.13 (0.11), respectively. The MI was significantly reduced in the continuous group when compared to the control (estimated difference [95% confidence interval {CI}], -0.56 [-0.81 to -0.31]; P < .01) and intermittent group (estimated difference [95% CI], -0.35 [-0.62 to -0.08]; P = .01). There was no significant difference in MI between the intermittent and control group (estimated difference [95% CI], -0.21 [-0.51 to 0.09]; P = .17). CONCLUSIONS: Human myometrium remains more responsive to subsequent oxytocin after intermittent compared to continuous exposure to oxytocin, most likely due to reduction in oxytocin receptor desensitization, or facilitation of receptor resensitization in the intermittent group. Hence, intermittent oxytocin administration during labor warrants further investigation as a technique to preserve uterine oxytocin responsiveness.

Comparison of Intermittent Intravenous Boluses of Phenylephrine and Norepinephrine to Prevent and Treat Spinal-Induced Hypotension in Cesarean Deliveries: Randomized Controlled Trial.

BACKGROUND: Phenylephrine (PE) is currently the vasopressor of choice to prevent and treat spinal-induced hypotension at cesarean delivery (CD). However, its use is often associated with reflex bradycardia. Norepinephrine (NE) has been put forward as an alternative vasopressor during CD due to its ability to treat hypotension while maintaining heart rate (HR). Recent studies have focused on the role of NE used as an infusion with favorable results compared to PE. No studies have compared equipotent bolus doses of PE and NE at CD. We hypothesized that when used in equipotent doses as an intermittent bolus regimen to prevent and treat spinal-induced hypotension, NE would result in a reduction in the incidence of bradycardia compared to PE. METHODS: This was a double-blind, randomized clinical trial of women undergoing elective CD under spinal anesthesia. Women were randomized to receive either PE 100 µg or NE 6 µg when the systolic blood pressure (SBP) was below baseline. In addition to the randomized treatment, ephedrine was given intravenously to both groups if the SBP was below baseline and the HR <60 bpm or if the SBP was <80% of baseline for 2 consecutive readings. The primary outcome was bradycardia (HR <50 bpm) in the predelivery period. Secondary outcomes included hypotension (SBP <80% of baseline), hypertension (SBP >120% of baseline), tachycardia (HR >120% of baseline), ≥2 episodes of bradycardia, nausea, vomiting, umbilical artery and vein blood gases, and Apgar scores. RESULTS: One hundred twelve patients were randomized. The incidence of bradycardia was lower in the NE group compared to the PE group (10.7% vs 37.5%; P < .001; difference [95% confidence interval {CI}], -26.8% [-41.8% to -11.7%]), implying an estimated 71% relative reduction (95% CI, 35%-88%). The distribution of the number of bradycardia episodes was also different between the 2 groups (P = .007). Further testing showed that the patients in the PE group had a higher risk of multiple bradycardia episodes (≥2 episodes) compared to the NE group (19.6% for PE versus 3.6% for NE; P = .008). The proportion of patients requiring rescue boluses of ephedrine was lower in the NE group compared to the PE group (7.2% for NE versus 21.4% for PE; P < .03; difference [95% CI], -14.3% [-27.0% to -1.6%]). No differences were observed between the 2 groups in the incidence of other secondary outcomes. CONCLUSIONS: When used as an intermittent bolus regimen to prevent and treat spinal-induced hypotension during CD, NE resulted in a significant reduction in the incidence of bradycardia as compared to an equipotent bolus regimen of PE. We conclude that the hemodynamic profile offered by NE during CD is superior to that of PE due to less fluctuations in HR and possibly cardiac output.

Obstetric neuraxial anesthesia at low platelet counts in the context of immune thrombocytopenia: a systematic review and meta-analysis.

PURPOSE: Primary immune thrombocytopenia (ITP) is an autoimmune condition affecting women of childbearing age that is characterized by diminished platelet quantity with preserved function. Although pregnant women with ITP are often denied obstetric neuraxial anesthesia (OBNA) with low platelet counts for fear of neuraxial hematoma, the true magnitude of neuraxial hematoma for ITP parturients is unknown. The aim of this systematic review and meta-analysis was to examine OBNA outcomes in ITP parturients with platelet counts below 100 x 109·L-1. SOURCE: Articles published in MEDLINE, Embase, Web of Science, Scopus, Cochrane, and PubMed in process until May 14, 2018 were searched. Two reviewers independently screened 954 articles by title and abstract, reviewed 62 full-texts, extracted data, and assessed risk of bias for 26 articles. PRINCIPAL FINDINGS: Of 291 pregnant women with ITP and platelet counts below 100 x 109·L-1, 166 received OBNA and 61 of these had platelet counts below 80 x 109·L-1. No neuraxial hematomas were reported. Meta-analysis of six studies showed higher platelet counts in those with OBNA than without (mean difference [MD], 19 x 109·L-1; 95% confidence interval [CI], 11 to 26; P < 0.001), with no difference between epidural and spinal anesthesia (MD, 0.4 x 109·L-1; 95% CI, -4 to 4; P = 0.86). CONCLUSION: Our study highlights continued reluctance to offer OBNA below the commonly quoted 80 x 109·L-1 platelet count, based largely on consensus and theoretical presumption of risk. This further negatively influences the accrual of large-scale data. The evidence of no neuraxial hematoma after OBNA provided herein offers support for considering neuraxial anesthesia at lower platelet count thresholds. Each patient should be afforded individualized discussion of risk and benefit relative to other analgesic measures. TRIAL REGISTRATION: PROSPERO (CRD42018059220); registered 2 August, 2018.

No. 383-Screening, Diagnosis, and Management of Placenta Accreta Spectrum Disorders.

BACKGROUND: Placenta accreta spectrum (PAS) disorders are a potentially life-threatening complication of pregnancy that demand coordinated interdisciplinary care to achieve safer outcomes. The rising incidence of this disease is due to a growing number of uterine surgical procedures, including the rising incidence of pregnancy following Caesarean section. OBJECTIVE: To provide current evidence-based guidelines on the optimal methods used to effectively screen, diagnose, and manage PAS disorders. METHODS: Members of the guideline committee were selected on the basis of their ongoing expertise in managing this condition across Canada and by practice setting. The committee reviewed all available evidence in the English medical literature, including published guidelines, and evaluated diagnostic tests, surgical procedures, and clinical outcomes. EVIDENCE: Published literature, including clinical practice guidelines, was retrieved through searches of Medline and The Cochrane Library to March 2018 using appropriate controlled vocabulary and key words. Results were restricted to systematic reviews, randomized controlled trials, and observational studies written in English. Searches were updated on a regular basis and incorporated in the guideline to July 2018. VALUES: The quality of evidence in this document was graded using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. RESULTS: This document reviews the evidence regarding the available diagnostic and surgical techniques used for optimal management of women with suspected PAS disorders, including anaesthesia and practical considerations for interdisciplinary care. BENEFITS, HARMS, AND COSTS: Implementation of the guideline recommendations will improve awareness of this disease and increase the proportion of affected women receiving interdisciplinary care in regional centres. CONCLUSIONS: Interdisciplinary team-based care providing accurate diagnostic services, coordinated planning, and safer surgery deliver effective care with improved clinical outcomes in comparison with alternative management. SUMMARY STATEMENTS: RECOMMENDATIONS.