Physiologic effects of stellate ganglion block: a result of complete ganglion blockade or the vertical spread of local anesthetic?

Traditionally, stellate ganglion blockade has been used for the diagnosis and treatment of upper extremity sympathetic pain. However, this treatment has not been shown to provide adequate sympathetic blockade of the upper extremities. This study demonstrates that a carefully performed upper thoracic sympathetic block with imaging guidance can result in a successful sympathetic blockade of the upper extremities. This study furthermore demonstrates that the occurrence of a Horners syndrome is not a testimony to a successful sympathetic block of the upper extremities.

The air-liquid interface and the pH and PCO2 of alkalinized local anaesthetic solutions.

The alkalinization of certain local anaesthetics with sodium bicarbonate hastens the onset of epidural analgesia. Increases in both the pH and PCO2 of the local anaesthetic are necessary to hasten onset. However, carbon dioxide can diffuse from local anaesthetic solutions following alkalinization with sodium bicarbonate and change both the pH and PCO2 of the mixture. This study examined changes in pH and PCO2 of three local anaesthetics reported to have a faster onset of analgesia following mixture with sodium bicarbonate and examined the effects of time and the local anaesthetic container air/liquid interface on the pH and PCO2 of the buffered local anaesthetic solutions. Bupivacaine 0.5%, lidocaine 2%, and chloroprocaine 2% were each buffered with sodium bicarbonate. The pH and PCO2 of each solution were measured at time 0 and at 5, 10, 15, 20, 30, 40, 50 and 60 min intervals. The solutions were placed in containers as follows: 30 ml in 40 ml containers, 10 ml in 40 ml containers, 10 ml in 13 ml containers, and 10 ml in polypropylene syringes. The pH and PCO2 increased following alkalinization but gradually decreased in all containers except in polypropylene syringes.