The Challenges of Ultrasound-guided Thoracic Paravertebral Blocks in Rib Fracture Patients

Abstract

Thoracic paravertebral blocks (TPVBs) provide an effective pain relief modality in conditions where thoracic epidurals are contraindicated. Historically, TPVBs were placed relying solely on the landmark-based technique, but the availability of ultrasound imaging makes it a valuable and practical tool during the placement of these blocks. TPVBs also provide numerous advantages over thoracic epidurals, namely, minimal hypotension, absence of urinary retention, lack of motor weakness, and remote risk of an epidural hematoma. Utilization of both landmark-based and ultrasound-guided techniques may increase the successful placement of a TPVB. This article reviews relevant sonoanatomy as it pertains to TPVBs. However, certain patient-related issues, including pneumothoraces, surgical emphysema, body habitus, and transverse process fractures, all may make imaging with ultrasound challenging. The changes noted on ultrasound imaging as a result of these issues will be further described in this review.

Keywords: chest trauma; nerve block; rib fractures; thoracic paraverterbral block; ultrasound.

Figure 1. Scanning technique to obtain the parasagittal/longitudinal view on a healthy volunteer

a, b) The probe is positioned in the midline longitudinal plane showing spinous processes (SP); c, d) The probe is positioned in the paramedian longitudinal plane depicting the lamina (white arrow); e, f) Moving the probe further lateral shows the transverse processes (TP), pleura (P), and paravertebral space (white arrows)

Figure 2. Parasagittal needle approach depicted on a healthy volunteer

Paravertebral blocks showing the orientation of a low-frequency probe in the longitudinal plane with the needle approaching cephalad to the probe

Figure 3. Ultrasound view of paravertebral space (red arrow) in the parasagittal view showing two transverse processes (TP) and pleura (P) in a healthy volunteer.

Figure 4. Intercostal placement of the ultrasound for a paravertebral block with the needle approaching lateral to medial shown here on healthy volunteer

Figure 5. Ultrasound view of the paravertebral space (red arrow) in the intercostal view showing the transverse process (TP) and pleura (P)

Spinous process (SP) and lamina (white arrow) are also seen in this view obtained from a healthy volunteer.

Figure 6. Ultrasound of the third intercostal space along the anterior axillary line

The lung point (ultrasound of the 3rd intercostal space along the anterior axillary line). A) Expiration. Absence of lung sliding, plus A-lines; B) M-mode shows the sudden (arrow) inspiratory appearance of the lung point. Permission to use this figure obtained by Lichtenstein et al. [7]