Table 1.

Probability of clinical consequences and complications in a 3-point rating scale based on our anatomical findings and on the technique used

Structures	Spread dye/plastic	Clinical consequences/complications	Clinical likelihood with technique used
Neurovascular bundle intercostal space	Yes	Intercostal block Block failure Vascular puncture	Likely Possible Possible
Endothoracic fascia	Yes	Indistinguishable from parietal pleura
Parietal pleura	Yes, not penetrated	Pneumothorax	Possible
Intervertebral foramen	Yes	Epidural or intrathecal spread local anesthetics Hematoma	Possible
Prevertebral space	Limited
Thoracic duct	No	Puncture	Unlikely
Azygos and hemi-azygos vessels	No	Vascular puncture	Possible
Sympathetic chain	Yes	Sympatic blockade horner syndrome	Likely
Paravertebral vessels	Yes	Vascular puncture	Possible