Does Ultrasound Increase the First-pass Success of Epidural Space Identification in Obese Parturients

Study Overview
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Brief Summary
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Obesity is associated with difficulties in epidural space catheterization. The investigators want to prove that a pre-procedural ultrasound exam of lumbar spine increase the first-pass success rate of the epidural space identification among obese parturients.

Detailed Description
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This study was a randomized controlled open trial with two parallel groups. Study was conducted in only one center : the maternity of University Hospital of Caen (Normandy, France) Written informed consent was obtained from eligible subjects after the pre-anesthetic interview in the 8th month of pregnancy. Operators were medical interns or residents in anesthesiology. Before inclusion, they all spent an individual interview in the aim to practice ultrasound exam of lumbar spine. Eligible subjects were full-term parturients with pre-pregnancy BMI ≥ 30 kg/m2 undergoing vaginal delivery and receiving epidural labor analgesia. Exclusion criteria were usual contraindications for neuraxial anesthesia, marked spinal deformity, previous spinal surgery and emergency context. The study subjects were randomly assigned to palpation or ultrasound using sealed opaque envelopes containing group allocation. Standard monitors were applied and patients were positioned sitting during landmark identification and throughout the anesthetic procedure. In control group, needle-puncture site was determinate by the conventional technique of cutaneous palpation. Conventional palpation of the anatomical landmarks was performed and the intercristal line (Tuffier) was assumed to cross the spine at L4 spinous process or L3-L4 interspace. The skin was marked with horizontal and vertical lines at the L3-L4 and L2-L3 interspaces. In experimental group, ultrasound exam of lumbar spine allowed to determinate the puncture site. A systematic approach described by Balki [1] was performed, using a portative ultrasound device with a 5-2 MHz curved array probe (Samsung HM70A, Samsung medical France, St-Ouen, France). The epidural space was located using a midline approach with loss of resistance (saline solution) using and 18-gauge Tuohy needle. After successful identification of the epidural space, a 20-gauge multiorifice epidural catheter was inserted through the Tuohy needle up to 5 cm into the epidural space.The epidural analgesia protocol was PCEA (Patient Controled Epidural Analgesia) using subsequent admixture : lévo-bupivacaïne (0,625 mg/ml), sufentanil (0,02 µ/ml), clonidine (37 µg/ml). The primary outcome was the rate of successful epidural space identification at the first needle pass (one skin puncture without redirection). Secondary outcomes are described further. Early procedural complications and delivery modalities (C-section, forceps) were notified. An interview was planned 48 hours after the procedure for each parturient in the aim to assess the maternal satisfaction and detect late procedure complications. Assuming α = 0.05 and β = 0.2 (80% power) risks and using the χ2 test, 28 patients were required in each group.

Official Title
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Does Preprocedural Ultrasound Exam of Lumbar Spine Increase the First-pass Success Rate of Epidural Space Identification Among Obese Parturients: A Randomized Controlled Open Trial

Conditions
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Epidural; Anesthesia

Intervention / Treatment
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* Device: Preprocedural ultrasound exam of lumbar spine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Full-term parturients (≥ 37 weeks of amenorrhea) With pre-pregnancy BMI ≥ 30 kg/m2 Admit for a vaginal delivery Receiving labour epidural analgesia Exclusion Criteria: Usual contraindications for neuraxial anesthesia (thrombocytopenia, coagulopathy, uncorrected hypovolemia, infected puncture site, intracranial hypertension) Emergency maternal and foetal cases Twin pregnancy Marked spinal deformity ou previous spinal surgery Refusal to participate
Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: randomized controlled open trial
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: palpation<br>Usual method to determinate needle puncture site | |
| Experimental: Ultrasound<br>Ultrasound preprocedural exam used to determinate needle puncture site | Device: Preprocedural ultrasound exam of lumbar spine<br>* Preprocedural ultrasound exam of lumbar spine used to determinate needle puncture site<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success of the epidural space identification at the first needle pass | Succes rate of the epidural space identification at the first needle pass (first skin puncture and without needle redirection) for each group | Baseline up to 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success of the epidural space identification at the first skin puncture | Success rate of the epidural space identification at the first needle pass (first skin puncture with at least one redirection) for each group | Baseline up to 1 hour | 
| Number of skin punctures | Number of skin punctures per parturient | Baseline up to 1 hour | 
| Number of needle redirections | Number of needle redirections per parturient | Baseline up to 1 hour | 
| Number of intervertebral space punctured | Number of intervertebral space punctured per parturient | Baseline up to 1 hour | 
| Duration of the epidural procedure | Duration of the epidural procedure in seconds, measured from the first skin puncture to the test dose | Baseline up to 1 hour | 
| Early Failed of the epidural analgesia | Early Failed epidural analgesia, defined by the epidural analgesia remplacement within 30 minutes | 30 minutes after the end of the procedure | 
| Verbal Rating Scale | Verbal Rating Scale (VRS) of pain measured after the epidural procedure : from 0 (no itch) to 10 (worst imaginable itch) | 30 minutes and 120 minutes after the epidural procedure | 
| Accidental Dural puncture | Occurence of accidental dural puncture during the epidural procedure | Baseline up to 1 hour | 
| Post dural puncture headache | Occurence of Post dural puncture headache after the epidural procedure | 48 hours after the epidural procedure | 
| Quality of epidural analgesia | Maternal perception of epidural analgesia quality during the labour : from 1 (very bad) to 5 (excellent) | 48 hours after the epidural procedure | 
| Maternal perception of the duration of the epidural procedure | Maternal perception of epidural procedure duration : from 1(very short) to 5 (very long) | 48 hours after the epidural procedure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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obesity, ultrasound, epidural analgesia, vaginal delivery