Preinsertion paramedian ultrasound guidance for epidural anesthesia.

Background: Ultrasound is receiving growing interest for improving the guidance of needle insertion in epidural anesthesia. Defining a paramedian ultrasound scanning technique would be helpful for correctly identifying the vertebral level. Finding surrogate measures of the depth of the epidural space may also improve the ease of scanning.

Adaptive ultrasound imaging of the lumbar spine for guidance of epidural anesthesia.

Ultrasound imaging can help in choosing the needle trajectory for epidural anesthesia but anatomical features are not always clear. Spatial compounding can emphasize structures; however, features in the beam-steered images are not aligned due to varying speeds of sound. A non-rigid registration method, called warping, shifts pixels of the beam-steered images to best match the reference image.

Instrumentation of the loss-of-resistance technique for epidural needle insertion.

Epidural anesthesia is the most common form of anesthesia in obstetrics. The loss-of-resistance to saline injection is used to confirm when the needle tip enters the epidural space. This procedure is highly dependent on skill and expertise, so it is useful to quantify the tissue resistance during insertion.

Instrumentation for epidural anesthesia.

A low-cost, sterilizable and unobtrusive instrumentation device was developed to quantify and study the loss-of-resistance technique in epidural anesthesia. In the porcine study, the rapid fall of the applied force, plunger displacement and fluid pressure, and the oral indication of the anesthesiologists were shown to be consistent with the loss-of-resistance. A model based on fluid leakage was developed to estimate the pressure from the force and displacement measurements, so that the pressure sensor could be omitted in human studies.