Randomized Assessment of the Optimal Time Interval Between Programmed Intermittent Epidural Boluses When Combined With the Dural Puncture Epidural Technique for Labor Analgesia.

Background: The dural puncture epidural (DPE) and programmed intermittent epidural bolus (PIEB) techniques are recent advances in neuraxial labor analgesia. Previous studies have investigated the PIEB optimal interval for effective analgesia when a standard epidural technique is used to initiate labor analgesia. However, it is unknown whether these findings are applicable when DPE is used.

Comparative dose-response study of hyperbaric ropivacaine for spinal anesthesia for cesarean delivery in singleton versus twin pregnancies.

Study Objective: It is controversial whether local anesthetic dose requirement for spinal anesthesia for cesarean delivery differs between patients with singleton and patients with multiple gestation pregnancies. The aim of this study was to determine and compare the ED and ED for hyperbaric ropivacaine used for spinal anesthesia for cesarean delivery in patients with singleton pregnancies versus patients with twin pregnancies.

Design: Prospective, randomized, comparative dose-finding study.

Norepinephrine or phenylephrine during spinal anaesthesia for Caesarean delivery: a randomised double-blind pragmatic non-inferiority study of neonatal outcome.

Background: Norepinephrine is an effective vasopressor during spinal anaesthesia for Caesarean delivery. However, before it can be fully recommended, possible adverse effects on neonatal outcome should be excluded. We aimed to test the hypothesis that umbilical arterial cord pH is at least as good (non-inferior) when norepinephrine is used compared with phenylephrine for treatment of hypotension.

A randomised double-blind dose-response study of weight-adjusted infusions of norepinephrine for preventing hypotension during combined spinal-epidural anaesthesia for Caesarean delivery.

Background: Norepinephrine infusion has been suggested as an effective method for preventing hypotension during spinal anaesthesia for Caesarean delivery. However, optimal dosing regimens for norepinephrine have not been well established. This study aimed to determine the dose-response characteristics of a weight-adjusted fixed-rate infusion of norepinephrine to prevent hypotension during neuraxial anaesthesia for Caesarean delivery.

Vasopressor drugs for the prevention and treatment of hypotension during neuraxial anaesthesia for Caesarean delivery: a Bayesian network meta-analysis of fetal and maternal outcomes.

Background: The optimal choice of vasopressor drugs for managing hypotension during neuraxial anaesthesia for Caesarean delivery is unclear. Although phenylephrine was recently recommended as a consensus choice, direct comparison of phenylephrine with vasopressors used in other healthcare settings is largely lacking. Therefore, we assessed this indirectly by collating data from relevant studies in this comprehensive network meta-analysis.

A Prospective, Randomized, Double-Blinded Study of the Effect of Intravenous Ondansetron on the Effective Dose in 50% of Subjects of Prophylactic Phenylephrine Infusions for Preventing Spinal Anesthesia-Induced Hypotension During Cesarean Delivery.

Background: Ondansetron has been shown to reduce the incidence of hypotension and vasopressor requirement during spinal anesthesia for obstetric and nonobstetric surgery. However, the magnitude of this effect has not been fully quantified. In this parallel-group, randomized, double-blinded study, we determined the effective dose in 50% of subjects (ED50) of a prophylactic phenylephrine infusion for preventing hypotension in patients who received a single dose of intravenous ondansetron 4 mg or saline control before combined spinal-epidural anesthesia for elective cesarean delivery.

Dose-Response Study of 4 Weight-Based Phenylephrine Infusion Regimens for Preventing Hypotension During Cesarean Delivery Under Combined Spinal-Epidural Anesthesia.

Background: Prophylactic IV infusion of phenylephrine has been recommended to prevent hypotension during spinal anesthesia for cesarean delivery. However, the optimal infusion dose is unknown. This study aimed to determine the infusion dose of phenylephrine that would be effective in preventing hypotension in 50% (ED50) and 90% (ED90) of patients when administered as a prophylactic infusion at a fixed rate based on the individual body weight.

Dose-Response Curves for Intrathecal Bupivacaine, Levobupivacaine, and Ropivacaine Given for Labor Analgesia in Nulliparous Women.

Background And Objectives: Bupivacaine, levobupivacaine, and ropivacaine are often given intrathecally for labor analgesia, but limited data are available for their dose-response properties in this context. The objective of this study was to describe the dose-response curves of these local anesthetics when given intrathecally for labor analgesia, to determine values for D50 (dose producing a 50% response) and to compare the calculated values of D50 for levobupivacaine and ropivacaine with those for bupivacaine.

Methods: With ethics approval and written consent, we randomized 270 nulliparous laboring patients requesting neuraxial analgesia at 5-cm cervical dilation or less to receive a single dose of intrathecal local anesthetic without opioid as part of a combined spinal-epidural technique.

A Random-allocation Graded Dose-Response Study of Norepinephrine and Phenylephrine for Treating Hypotension during Spinal Anesthesia for Cesarean Delivery.

Background: Norepinephrine has been investigated as a potential alterative to phenylephrine for maintaining blood pressure during spinal anesthesia for cesarean delivery with the advantage of less depression of maternal heart rate and cardiac output. However, the relative potencies of these two vasopressors have not been fully determined in this context.

Methods: In a random-allocation, graded dose-response study, 180 healthy patients undergoing spinal anesthesia for elective cesarean delivery received a single bolus of norepinephrine in one of six different doses ranging from 4 to 12 µg or phenylephrine in one of six different doses ranging from 60 to 200 µg to treat the first episode of hypotension.

Prophylactic Norepinephrine Infusion for Preventing Hypotension During Spinal Anesthesia for Cesarean Delivery.

Background: The use of norepinephrine for maintaining blood pressure (BP) during spinal anesthesia for cesarean delivery has been described recently. However, its administration by titrated manually controlled infusion in this context has not been evaluated.

Methods: In a double-blinded, randomized controlled trial, 110 healthy women having spinal anesthesia for elective cesarean delivery were randomly allocated to 1 of 2 groups.

Closed-Loop Feedback Computer-Controlled Phenylephrine for Maintenance of Blood Pressure During Spinal Anesthesia for Cesarean Delivery: A Randomized Trial Comparing Automated Boluses Versus Infusion.

Background: We previously described the use of closed-loop feedback computer-controlled infusion of phenylephrine for maintaining blood pressure (BP) during spinal anesthesia for cesarean delivery. In this study, we report a modified system in which phenylephrine is delivered by intermittent boluses rather than infusion. We hypothesized that the use of computer-controlled boluses would result in more precise control of BP compared with infusions.

The use of vasopressors during spinal anaesthesia for caesarean section.

Purpose Of Review: Hypotension remains one of the most researched subjects in obstetric anaesthesia. The purpose of this study is to review the most recent published articles on the use of vasopressors during spinal anaesthesia for caesarean section.

Recent Findings: Despite continued research indicating advantages of phenylephrine over ephedrine, practitioners in some countries continue to favour ephedrine.

Norepinephrine Intermittent Intravenous Boluses to Prevent Hypotension During Spinal Anesthesia for Cesarean Delivery: A Sequential Allocation Dose-Finding Study.

Background: The use of phenylephrine as the first-line agent for prevention and treatment of maternal hypotension during cesarean delivery (CD) may reduce cardiac output, posing a theoretical risk to mother and fetus. Norepinephrine has been suggested as a potential alternative, because its β-adrenergic effects might result in greater heart rate and cardiac output than phenylephrine. The use of norepinephrine to prevent and treat hypotension during CD is new, and its use as a bolus has not been fully determined in this context.

Performance of a closed-loop feedback computer-controlled infusion system for maintaining blood pressure during spinal anaesthesia for caesarean section: a randomized controlled comparison of norepinephrine versus phenylephrine.

Closed-loop feedback computer-controlled vasopressor infusion has been previously described for maintaining blood pressure during spinal anaesthesia for caesarean section but there are limited data available comparing the relative performance of different vasopressors. The aim of this study was to compare the performance of norepinephrine versus phenylephrine in this system. Data from a randomized, two-arm parallel group, double-blinded controlled trial were reanalyzed.

Randomized double-blinded comparison of norepinephrine and phenylephrine for maintenance of blood pressure during spinal anesthesia for cesarean delivery.

Background: During spinal anesthesia for cesarean delivery, phenylephrine can cause reflexive decreases in maternal heart rate and cardiac output. Norepinephrine has weak β-adrenergic receptor agonist activity in addition to potent α-adrenergic receptor activity and therefore may be suitable for maintaining blood pressure with less negative effects on heart rate and cardiac output compared with phenylephrine.

Methods: In a randomized, double-blinded study, 104 healthy patients having cesarean delivery under spinal anesthesia were randomized to have systolic blood pressure maintained with a computer-controlled infusion of norepinephrine 5 μg/ml or phenylephrine 100 μg/ml.

Synergistic interaction between fentanyl and bupivacaine given intrathecally for labor analgesia.

Background: Lipophilic opioids and local anesthetics are often given intrathecally in combination for labor analgesia. However, the nature of the pharmacologic interaction between these drugs has not been clearly elucidated in humans.

Methods: Three hundred nulliparous women randomly received 1 of 30 different combinations of fentanyl and bupivacaine intrathecally using a combined spinal-epidural technique for analgesia in the first stage of labor.

Regional hemodynamic changes after an axillary brachial plexus block: a pulsed-wave Doppler ultrasound study.

Background: Brachial plexus block (BPB) causes vasodilatation and an increase in blood flow to the ipsilateral upper limb. However, no reports have comprehensively evaluated the regional hemodynamic changes after a BPB.

Methods: Eight healthy adult patients who were scheduled for elective hand surgery had an ultrasound-guided axillary BPB for anesthesia.

The effect of maternal and fetal β2-adrenoceptor and nitric oxide synthase genotype on vasopressor requirement and fetal acid-base status during spinal anesthesia for cesarean delivery.

Background: Previous work demonstrated that maternal haplotypes of the β₂-adrenoceptor gene (ADRB2) influence ephedrine requirements during cesarean delivery. The use of ephedrine versus a pure α-adrenergic agonist such as phenylephrine has been associated with lower umbilical artery (UA) pH, thought to be secondary to increased fetal metabolism. There are no data evaluating the effect of fetal/neonatal genotypes on the metabolic response to maternally administered vasopressors.

Gelatin-agar lumbosacral spine phantom: a simple model for learning the basic skills required to perform real-time sonographically guided central neuraxial blocks.

This report describes the preparation of a gelatin-agar spine phantom that was used for spinal sonography and to practice the hand-eye coordination skills required to perform sonographically guided central neuraxial blocks. The phantom was prepared by embedding a lumbosacral spine model into a mixture of gelatin and agar in a plastic box. Cellulose powder and chlorhexidine were also added to the mixture, after which it was allowed to solidify.

Fetoscopic laser photocoagulation in the management of twin-twin transfusion syndrome: local experience from Hong Kong.

Objective: To review the perinatal outcome of monochorionic twin pregnancies treated by fetoscopic laser coagulation for twin-twin transfusion syndrome.

Design: Retrospective study.

Setting: A university teaching hospital in Hong Kong.