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

Impact of preoperative pleural effusion on ultrasound- and pressure-guided thoracic paravertebral block: a prospective observational study

OBJECTIVE

To evaluate the impact of preoperative pleural effusion on the ultrasound visualization of the paravertebral space (PVS), thoracic paravertebral nerve block administered by anesthesiologists, and to investigate whether ultrasound combined with pressure guidance can assist in locating the paravertebral space in patients with pleural effusion.

METHODS

This prospective observational study enrolled patients undergoing thoracic surgery at Beijing Jishuitan Hospital between September 2021 and September 2022. Patients were categorized into two groups based on preoperative CT findings: the pleural effusion group (n = 40) and the non-pleural effusion group (n = 40). Prior to the induction of general anesthesia, all patients were placed in a lateral position. Thoracic paravertebral nerve block (TPVB) was administered using ultrasound guidance combined with pressure monitoring, with a 20 ml of 0.5% ropivacaine.

RESULTS

Parameters recorded included the duration of puncture and ultrasound pre-scan for TPVB, the ultrasound image definition score of the PVS, the pressure in the external intercostal muscle and PVS, and additional relevant indicators. Mean arterial pressure (MAP) and heart rate (HR) were measured before anesthesia induction, post-induction, and during skin incision. Compared to the non-pleural effusion group, the pleural effusion group demonstrated prolonged ultrasound pre-scan and puncture durations. The PVS definition score, the ventral displacement of the pleura, and the accuracy of resident anesthesiologists in identifying the PVS were all significantly lower in the pleural effusion group (p < 0.05). Compared to non-pleural effusion group, the pleural effusion group had significantly higher pressure in PVS. In the pleural effusion group, the pressure in PVS was significantly lower than that in external intercostal muscle (p < 0.05). No significant differences were observed in MAP and HR between the two groups before anesthesia induction, post-induction and during skin incision (p > 0.05).

CONCLUSION

Preoperative pleural effusion is associated with reduced clarity of ultrasound visualization of the PVS, and extended procedural durations for anesthesiologists, thereby increasing the complexity of TPVB. Pressure detection during TPVB implementation can assist in locating the position of the puncture needle. For anesthesiologists with less experience, TPVB should be carefully performed in patients with preoperative pleural effusion.

TRIAL REGISTRATION

The trial was prospectively registered with the Chinese Clinical Trial Registry under registration number ChiCTR2100050582, on August 30, 2021.

Ultrasound-Guided Extraforaminal Thoracic Nerve Root Block Through the Midpoint of the Inferior Articular Process and the Parietal Pleura: A Clinical Application of Thoracic Paravertebral Nerve Block

Purpose

Thoracic nerve root (TNR) block is performed primarily under computed tomography or X-ray fluoroscopy but is associated with radiation exposure. Ultrasound requires no radiation and distinguishes vessels, nerves, pleura, and other tissues. Few reports of ultrasound-guided TNR (US-TNR) block have been described, and the puncture end point has not been clearly defined. Herein, we evaluated the feasibility of US-TNR block using the midpoint of the inferior articular process (IAP) and parietal pleura (PP) as the puncture end point.

Patients and Methods

A prospective series of 10 patients with Herpes Zoster-associated pain underwent US-TNR-guided block performed using an in-plane technique with the midpoint of thoracic IAP and PP as the puncture end points of ultrasonography. The US-TNR block procedure was performed with ultrasound as the primary imaging tool followed by fluoroscopic confirmation.

Results

In all patients, the needle tips were visible at the lateral margin of the pedicle in the anteroposterior view and at the extraforaminal zone in the lateral view. The TNR and dorsal root ganglion (DRG) were delineated in all 10 patients. Furthermore, 2 mL of radiopaque agent could delineate the epidural space in 8 patients and the thoracic paravertebral (TPV) space in the other 2 patients. All patients developed numbness along the corresponding dermatome 30 min after injection of local anesthetics. The numeric rating scale (NRS) score at baseline, and at two- and four-week follow-ups were 6.50 ± 1.35, 3.50 ± 0.85 (vs NRS at baseline, P < 0.01), and 4.00 ± 0.82 (vs NRS at baseline, P < 0.01), respectively.

Conclusion

This study demonstrated the feasibility of US-TNR block using the in-plane technique with the midpoint of thoracic IAP and PP as the puncture end point to effectively block the TNR and DRG. This technique is an accurate clinical application of TPV nerve block and provides a potential therapeutic option for the treatment of neuropathic pain.