Color Doppler Ultrasound to Locate Needle in Labor Epidural

Overview

Color Flow Doppler (CFD) utilizes Doppler information obtained from signals sent to and received from a transducer. This information is color-encoded and then displayed as color on an overlay of the two-dimensional image. The color scale represents both speed and direction of flow within a discrete area of the image. CFD has been recently used to determine the position of the epidural catheter. However its role in labor epidural has yet to be defined. This study describes the use of CFD to confirm the position of the tip of the epidural needle in the context of labor analgesia. This study hypothesized that CFD is a feasible method for identifying proper epidural needle placement prior to epidural catheter advancement.

After obtaining approval by the Institutional Review Board and a waiver of informed consent, thirty-five pregnant patients who underwent an ultrasound guided labor epidural between August of 2017 and June of 2018, were included in this retrospective review. The ultrasound guided labor epidural was used in those in which an anticipated technical difficulty with landmark epidural space localization was expected. These included those patients with diagnosis of obesity and lumbar scoliosis, as well as those with poorly defined surface lumbar bone anatomy. Patients with history of spine surgery were excluded. Patient data were obtained from the institutional electronic medical records. Demographic data, intervertebral level of insertion, dermatome level, and failure rate of epidural needle placement using color flow Doppler were noted for each patient. Labor analgesia was obtained via a combined spinal epidural technique. Sterile preparation and draping of the area was followed by placement of a curvilinear ultrasound transducer in a sterile sheath. The ultrasound was used to identify the interspinous space. The epidural needle was guided with the use of real time ultrasound by the use of an out of plane technique. A two hand technique was used to manipulate the needle and the ultrasound probe. A 17G Tuohy needle (B. Braun Medical Inc, Bethlhem, PA, USA) was advanced until loss of resistance to normal saline was attained. Confirmation of the epidural space with the use of color flow Doppler (CFD) was then obtained after injection of up to 10 mL of normal saline through the epidural needle. A 27G pencil-point spinal needle (B. Braun Medical Inc, Bethlhem, PA, USA) was then introduced through the epidural needle until cerebro-spinal fluid (CSF) was obtained. Use of intrathecal fentanyl or local anesthetic plus fentanyl was then used as a bolus in the spinal space. A 21G epidural catheter (B. Braun Medical Inc, Bethlhem, PA, USA) was then threaded into the epidural space.