Effects of posture on the spread of isobaric and hyperbaric amethocaine

The effects of posture on the spread of isobaric and hyperbaric amethocaine were studied after intrathecal injection in 60 patients. Gravity had no effect on the spread of isobaric solutions and, while hyperbaric solutions did spread under the effect of gravity, it was found that posture could not be used to control spread effectively. The results also show that the dose of local anaesthetic injected had a more important effect on the duration of blockade than on the spread.