Ultrasound-Assisted Paramedian Thoracic Epidural
We read with great interest the recent article by Auyong et al1 evaluating ultrasound-assisted thoracic epidural placement. For our obese patient population undergoing abdominal and thoracic surgery, an ultrasound-guided approach has been essential in placing thoracic epidurals. Traditional methods of placing a thoracic epidural involved landmark-based techniques, including paramedian and midline approaches. Paramedian technique is preferred over midline to access the thoracic epidural space because of the steep angulation of the spinous processes of the thoracic vertebrae. Ultrasound has been used with great success to assist in placement of lumbar epidurals; however, the use of ultrasound for guidance in thoracic epidurals is still not widespread.2 Ultrasound has been shown to help visualize landmarks but still demonstrates challenges in visualizing neuraxial structures. We would like to share a different technique with a novel approach in placing an ultrasound-assisted thoracic epidural.
In our morbidly obese patients, after multiple failed attempts with the landmark technique, with the patient in sitting position, a low-frequency curvilinear ultrasound probe is used to identify the spinous process of T9 and lamina of T10 (Fig. 1) in a transverse plane. An 18-gauge Tuohy needle was advanced in an in-plane approach to the junction of the spinous process and lamina. The ultrasound is then removed, and the depth of the needle is noted here. The needle is then directed cephalad along the lamina, while maintaining the medial angulation, as with the traditional paramedian approach. Once the needle can be advanced deeper than the previously marked depth, a glass syringe is attached and used to check for loss of resistance in the usual fashion.3
Prior to the use of ultrasound, there were multiple unsuccessful attempts with the landmark technique because of difficulty locating any bony landmarks including scapula, posterior superior iliac spine, or spinous processes with palpation in our patient population of increasing size. Using ultrasound, we are able to count the transverse processes down to the level of T9 and locate the necessary landmarks so that we may direct the needle to the necessary starting point for placement of thoracic epidurals and ultimately provide analgesia for the patient.4
Narcotic-sparing techniques are of particular importance in this same patient population, where procedures tend to be more challenging. We hope that the utilization of ultrasound to assist placement of thoracic epidurals will continue to grow in popularity once practitioners are able to see its ease of use. Ultrasound machines are usually readily available to anesthesiologists in modern operating suites because of their standard use for line placement and peripheral nerve blockade.