Samuel Lunenfeld Research Institute

Neuraxial analgesia has shown to be the gold standard for effective labor pain relief, offering numerous benefits including enhanced pain control and maternal satisfaction. The methods to achieve neuraxial analgesia include lumbar epidural (LE), and combined spinal epidural (CSE). While LE may not consistently provide optimal pain relief, leading to frequent maternal requests for supplemental analgesics, CSE presents a promising advancement. This is due to the rapid onset of pain relief from intrathecal components, complemented by the longer-lasting effects of epidural medications. Intrathecal drugs have demonstrated the ability to offer more symmetrical blockades compared to epidurally administered medications. Nonetheless, some clinicians remain cautious about CSE due to the potential for increased pain when transitioning from spinal to less effective epidural analgesia. Long-acting opioids like morphine in the intrathecal space may mitigate this problem by providing transitional analgesia to the laboring parturient.
The primary aim of this randomized controlled trial is to provide evidence of whether the addition of 100 mcg of morphine in the intrathecal (spinal) component of CSE reduces the rate of breakthrough pain during labor.

This study aims to explore the patients' and providers' perspectives and inform future anesthetic practice for patients undergoing unexpected cesarean delivery (CD) under general anesthetic (GA). The consideration of patients' concerns, preferences, expectations, and suggestions may lead to enhanced patient satisfaction, compliance, and quality of care that future patients receive during unexpected CD under GA. The investigators will possibly be able to identify gaps in procedural performance that warrant further investigation during the second phase of this study which will contribute to improvement of overall patient care. During the third phase, educational material will be generated from patient insights and will be distributed to the Department of Anesthesia, Department of Obstetrics and Gynaecology, Labour and Delivery Nurses and team of Anesthesia Assistants and Respiratory Therapists.

Combined spinal-epidural (CSE) for labor analgesia has been used for many years and is practiced commonly at our institution, especially when the patient requests immediate pain relief. CSE is not only beneficial for its faster onset of analgesia, but also it is favorable in relation to the need for rescue analgesia, urinary retention, and rate of instrumental delivery compared to the traditional epidural. Despite its beneficial effects, there is a risk of about 15-30% of developing abnormal fetal heart rate following CSE. This is self-resolving with minimal or no intervention. Although the cause of fetal bradycardia is not fully elucidated, variations in uterine artery blood flow after epidural analgesia are thought to be due to the interaction of numerous events related to blockade of sympathetic innervations, fluid administration, maternal hypotension, uterine vascular effects of sympathetic block, fluctuations in circulating catecholamines, and possibly the effect of opioids. Similar mechanism is thought to be a cause of fetal bradycardia after the CSE with its faster onset and superior block.
Maternal or fetal circulation during labor can be assessed using continuous-wave Doppler ultrasound to monitor maternal uterine artery (UtA) and fetal umbilical artery (UmA) velocity waveforms to detect changes in blood flow. The velocimetry indices mentioned above have been often used to assess the changes in the blood flow before and after the induction of epidural analgesia during labor in several studies. Although there are some studies regarding the effect of labor epidural analgesia using velocimetry indices, but there is currently no published study evaluating velocimetry indices of uterine and umbilical arteries before and after the induction of CSE. Thus, the aim of this study is to investigate the impact of CSE to maternal and fetal blood flow to evaluate the relationships.
The investigators hypothesize that both uterine artery and umbilical artery blood flow are reduced after the induction of CSE, which may be responsible for the occurrence of fetal bradycardia.