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.
- Nerve Block
- Pain, Postoperative
- Acute Pain
Data availability statement
Data are available on reasonable request.
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Contributors LL-W, BI and AB designed the study, EB initiated the study and submitted to IRB, LL-W and EB collected the data, AJ, CS and LL-W analyzed and interpreted the data, AJ, LL-W drafted the report, all authors participated in critical revision of the article, AJ, LL-W and CS approved the final version to be published.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.