Ultrasound High BMI Study

Placement of neuraxial blocks is commonly achieved by palpating surface landmarks. This somewhat "blind" technique to identify the spinal space becomes more difficult and less reliable in obese patients. Ultrasound devices have become common and successful with blocks and venous access, both involving mostly soft tissues. Application of conventional ultrasound for neuraxial blocks has been limited by its bulkiness, limited imaging for bony structures and a long learning curve. A newly developed pocket-size ultrasound addresses these limitations by providing real-time pattern recognition for spinal bony structures and 3D overlay for recognition of midline spinous process and intervertebral space using an automated artificial intelligent algorithm. The hypothesis is that ultrasound guidance will reduce time to epidural placement and reduce number of passes in obese patients.

Inclusion criteria

• Subject requesting and consenting for a labor epidural, aged 18-50 and BMI between 35-59.9 at admission for labor.
• Subject with American Society of Anesthesiologists score equal to or less than III.
• Subject with singleton gestation equal to or greater than 37 weeks.
• Subjects with planned labor epidural in sitting position.

Exclusion criteria

• Patients with urgent or emergent diagnoses involving the health of the patient or child, such as abnormal fetal heart tracing.
• Patients with major back abnormalities (back surgery, significant scoliosis).
• Patients with contra-indication to neuraxial block (bleeding risk, local anesthetic allergy).
• Patients having cesarean section or combined spinal epidural.
• Patients whose epidurals are performed by residents in first month of obstetric rotation and/or having performed fewer than 20 labor epidurals in total.
• Patient needing a translator for procedure.
• Patients who are prisoners.