Abstract

A series of experiments were conducted to evaluate the effects of hypobaric, isobaric, and hyperbaric solutions of 0.5% tetracaine administered intrathecally to sheep. In a second series of similar experiments, the effect of alterations in local anesthetic concentration was studied following the subarachnoid injection of 0.25%, 0.5% and 1.0% hyperbaric tetracaine. The results indicate no statistically significant difference in onset, duration or spread of anesthesia between the test solutions of different baricity. A significantly longer duration of anesthesia was observed with the 0.5 and 1.0% concentrations of tetracaine as compared to the 0.25% concentration. However, no difference in onset and spread of anesthesia was observed with the various concentrations of tetracaine.