A multifactorial approach to the factors influencing determination of paravertebral depth

Empirical guide to a safe thoracic paravertebral block based on dimensions of paravertebral space when ultrasound visualization is challenging

Although ultrasound (US) guidance is the mainstay technique for performing thoracic paravertebral blocks, situations arise when US imaging is limited due to subcutaneous emphysema or extremely deep structures. A detailed understanding of the anatomical structures of the paravertebral space can be strategic to safely and accurately perform a landmark-based or US-assisted approach. As such, we aimed to provide an anatomic roadmap to assist physicians. We examined 50 chest CT scans, measuring the distances of the bony structures and soft-tissue surrounding the thoracic paravertebral block at the 2nd/3rd (upper), 5th/6th (middle), and 9th/10th (lower) thoracic vertebral levels. This review of radiology records controlled for individual differences in body mass index, gender, and thoracic level. Midline to the lateral aspect of the transverse process (TP), the anterior-to-posterior distance of TP to pleura, and rib thickness range widely based on gender and thoracic level. The mean thickness of the TP is 0.9±0.1 cm in women and 1.1±0.2 cm in men. The best target for initial needle insertion from the midline (mean length of TP minus 2 SDs) distance would be 2.5 cm (upper thoracic)/2.2 cm (middle thoracic)/1.8 cm (lower thoracic) for females and 2.7 cm (upper)/2.5 cm (middle)/2.0 cm (lower thoracic) for males, with consideration that the lower thoracic region allows for a lower margin of error in the lateral dimension because of shorter TP. There are different dimensions for the key bony landmarks of a thoracic paravertebral block between males and females, which have not been previously described. These differences warrant adjustment of landmark-based or US-assisted approach to thoracic paravertebral space block for male and female patients.

Single-dose, bilateral paravertebral block plus intravenous sufentanil analgesia in patients with esophageal cancer undergoing combined thoracoscopic-laparoscopic esophagectomy: a safe and effective alternative

OBJECTIVE

Paravertebral block (PVB) has been shown to be an ideal aid for analgesia after thoracic or abdominal surgery. The authors studied the safety and efficacy of the single-dose and bilateral ultrasound-guided (USG)-PVB before combined thoracoscopic-laparoscopic esophagectomy (TLE) along with intravenous sufentanil analgesia as a method of pain relief in comparison with intravenous sufentanil as a sole analgesic agent.

DESIGN

Prospective, randomized study.

SETTING

Single university hospital.

PARTICIPANTS

Fifty-two patients undergoing TLE.

INTERVENTIONS

A USG-PVB was performed before surgery using a solution of 30 mL of 0.5% ropivacaine by 3 injections of 10 mL each at the right T5 and bilateral T8 (PVB group, n=26) or the saline injection of 10 mL at every site (control group, n=26).

MEASUREMENTS AND MAIN RESULTS

Successful PVBs were achieved in all patients of the PVB group. Intraoperative mean remifentanil usage and end-tidal sevoflurane concentration were lower in the PVB group (p<0.001). Hemodynamic parameters were stable in both groups. Postoperative pain scores both at rest and on coughing were lower during the first 8 hours in the PVB group than those in the control group (p<0.05). Cumulative sufentanil consumption delivered by patient-controlled analgesia (PCA) was significantly lower in the PVB group at all time points (p<0.05). Postoperative pulmonary function was better at the third postoperative day in the PVB group (p<0.05), with quicker hospital discharge and lower hospital costs (p<0.05).

CONCLUSIONS

The single-dose and bilateral PVB given before TLE combined with sufentanil may provide better postoperative analgesia and early discharge in patients undergoing TLE.

Paravertebral blocks

Paravertebral blocks have been demonstrated to represent an interesting alternative to epidural, especially for the management of perioperative and trauma pain. Initially performed mostly as single-shot blocks for breast surgery, thoracotomy, and hernia repairs in adults and children, presently these blocks are also used for placement of a paravertebral catheter, either unilateral or bilateral. Although complications associated with the performance of these blocks are infrequent, the use of ultrasound-guided approaches, which allow performing the block under direct vision, is becoming the standard in most groups performing these blocks routinely.