Ropivacaine 0.75% Versus Levobupivacaine 0.5% for Conversion of Labour Epidural

Study Overview
=================
Brief Summary
-----------------
The aim of this trial is to compare the local anaesthetic ropivacaine to local anaesthetic levobupivacaine in converting the standard patient controlled labour epidural to provide anaesthesia for an emergency Caesarean section. This is a technique commonly known as an epidural top-up. The investigators set out to disprove the hypothesis that there is no difference between the 2 local anaesthetics in the time of onset and number of times epidural top-up needs supplementing during surgery.

Detailed Description
-----------------
In a randomised controlled trial involving 45 patients the speed of onset of the effects of 20mls of 0.75% ropivacaine was found to be similar to that of 20mls of 0.5% bupivacaine1. However it was also found to be more efficacious at preventing 'breakthrough' pain and therefore had a lower intra-operative supplementation rate. Unfortunately the study was probably not powered adequately to confirm this finding. Bupivacaine has now largely been replaced in the this field by the less cardio-toxic stereoisomer levobupivacaine. A trial comparing 0.75% ropivacaine to 0.5% levobupivacaine and a lignocaine/adrenaline/fentanyl mixture was conducted in Singapore in 20082. It did not show a clinical difference between any of the agents. Whether the population studied is comparable to that in the UK is doubtful and it was not adequately powered to detect a difference in intra-operative supplementation rate. Local experience has shown ropivacaine 0.75% to provide a block with a rapid onset that has little requirement for supplementation intra-operatively. The need to supplement a local anaesthetic block during surgery means that the mother is experiencing a degree of pain that is unacceptable and we view this as a major consideration in choice of local anaesthetic for an epidural top-up. Whilst speed of onset is important, in that it influences the decision to delivery time of the baby, the evaluation of intraoperative supplementation will be a major focus of this trial.

Official Title
-----------------
Ropivacaine 0.75% Versus Levobupivacaine 0.5% for Conversion of Labour Epidural to Surgical Anaesthesia for Emergency Caesarean Section.

Conditions
-----------------
Caesarean Section

Intervention / Treatment
-----------------
* Drug: 0.5% levobupivacaine
* Drug: 0.75% Ropivacaine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Any subject requiring a grade 2 or 3 EmCS on the Hospital Birth Centre, St Thomas' who has: Labour analgesia provided by the standard patient controlled epidural (solution containing 0.1% levobupivacaine and 2mcg/ml fentanyl). That is providing analgesia via the patient controlled epidural analgesia infusion pump without the need for multiple extra boluses of epidural local anaesthetic and or opiates from the anaesthetist on the labour ward.. Singleton pregnancy. Established labour, determined by the midwife responsible for the patient (usually by vaginal examination of the cervix). Gestation >36 weeks No complex past medical history according to the judgement of the investigator > 18 years of age EmCS starts between the hours 0800 and 1800. The ability to understand the patient information sheet and willing to provide informed consent. Had a minimal total dose of 50mcg of fentanyl since insertion of epidural Exclusion Criteria: Pre-eclampsia / Eclampsia Antepartum haemorrhage Any congenital, structural or ischaemic heart disease. Category 1 EmCS. Participation in another therapeutic study in the last 12 weeks. -

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 0.5% levobupivacaine<br>Participants given 15mls of 0.5% levobupivacaine as the solution for their epidural top-up | Drug: 0.5% levobupivacaine<br>* 15mls of a 5mg/ml solution of the local anaesthetic levobupivacaine given via the epidural catheter.<br>* Other names: 0.5% Chirocaine;|
| Active Comparator: 0.75% Rpoivacaine<br>Participants given 15mls of 0.75% ropivacaine as the solution for their epidural top-up. | Drug: 0.75% Ropivacaine<br>* 15mls of a 7.5mg/ml solution of the local anaesthetic ropivacaine given via the epidural catheter.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Supplementation Rate | The number of times the epidural anaesthetic requires intra-operative supplementation with more study solution or another drug for pain. | During operation (approximately 1 hour ) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pre-operative supplementation | If further 5mls of study solution is required to achieve block height suitable for surgery to start. | 10-45mins (top-up to start of surgery) | 
| Pain | Incidence of breakthrough pain and its intensity during the operative phase of the Caesarean section | During operation (approximately 1 hour) | 
| Conversion Rate | If the epidural anaesthetic needs to be converted to spinal anaesthetic or general anaesthetic as it is not adequate for conduction of a Caesarean section | At any point between epidural top-up and end of operation (approximately 90mins from epidural top-up) | 
| Side effects | Occurrence of any of nausea, vomiting, itching and shivering during the specified time period | At any point between top-up of epidural and end of operation (approximately 90mins from epidural top-up) | 
| Blood pressure supplementation rate | Use of the vasopressor phenylephrine and Hartmannn's solution to be given if mean arterial BP drops greater than 30% below baseline or systolic BP of <100mg Hg. | At any point from top-up of epidural to end of operation (approximately 90mins from epidural top-up) | 
| Patient Satisfaction | Maternal satisfaction, asked to verbally score from 1-10 their satisfaction with the anaesthetic. | Prior to leaving operating theatre (approximatelty 120 minutes from epidural top-up) | 
| Motor block | Scored using the Bromage scoring system asking patient to raise legs and noting how able they are to do this. | prior to top-up and prior to leaving theatre (approximatelty 120 minutes from epidural top-up). | 
| Fetal Wellbeing | Neonatal Apgar scores at 1 and 5 minutes after delivery. pH of umbilical blood following delivery | After delivery (approximately 5-10 minutes from start of surgery) | 
| Onset Time | The time elapsed between administration of the top-up and onset of anaesthesia suitable for surgery to proceed. Defined as a loss of sensation to cold to T4 dermatomal level. | From administration of epidural top-up (approximately 10-45 minutes) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
epidural top-up, emergency Caesarean section