Does Preprocedural Ultrasound Increase the First-Pass Success Rate of Epidural Catheterization Before Cesarean Delivery? A Randomized Controlled Trial. Tawfik et al. Anesthesia & Analgesia, 124 (3): 851-856124 (2017)
There is an argument that ultrasound may increase the efficacy and safety of epidural catheterisation, particularly in difficult cases, but the current obstetric body of evidence is out of date and often the study designs are non-blinded and inconsistent. This team wanted to compare conventional palpating techniques for epidural insertion for lower segment Caesarean section (LSCS) delivery with ultrasound-assisted placement.
Use of pre-procedural ultrasound will increase the success rate of epidural catheterisation at the first needle pass.
Inclusion criteria: ASA 2, full-term, singleton pregnancy, elective LSCS, double-interspace combined spinal epidural
Exclusion criteria: age <19 or >40, BMI >35, labour, contraindication to neuroaxial block, marked spinal deformity, previous spinal surgery, impalpable anatomical landmarks
This was a double-blind randomised control trial, with eligible patients allocated by a computer-generated table of random numbers to either systematic spinal ultrasound or palpation group. A single experienced clinician performed all procedures with investigators and patients blinded to the allocations. The primary outcome measure was the rate of successful epidural catheterisation at first pass, and secondary outcomes included number of needle passes and skin punctures, duration of procedure, patient satisfaction scores and complications.
110 patients were randomised with data from 108 analysed, and the two others accounted for. The two groups had similar baseline characteristics and there was no significant difference in the primary or secondary outcome measures.
The study failed to show significant improvement in rate of successful epidural catheterisation at first pass when using pre-procedural ultrasound. The authors felt that their hypothesis was not supported and different to other studies’ results because of their exclusion criteria. It was acknowledged that the study was not powered to compare complications.
This was a valid trial addressing a clearly focused issue and patients were fairly randomised and all efforts made to prevent bias by blinding both patients and investigators. All patients were accounted for and the two groups similar and treated equally aside from the experimental intervention.
The sample size is relatively small, and the results cannot be applied in my context as we do not usually use a double interspace CSE technique in my local hospitals. Although the time taken in each procedure was measured, the time for the ultrasound technique was not measured, which is a clinically important outcome.
Although this was a well-run trial, there was no significant difference between the groups and it will fail to make a difference to my practice.
Summary by Dr Sarah Wintle