[Effects of solvent, baricity and dextrose concentration of 0.5% tetracaine solution on the efficacy of spinal anesthesia].

In 108 spinal anesthetic cases, 2.36 ml of each of five 0.5% tetracaine solutions, either with distilled water (DW), normal saline (NS) or different concentrations of dextrose (2.5%-2.5 G, 5%-5 G, 10%-10 G) was injected intrathecally at the L2/3 or L3/4 interspace. The specific gravity and osmotic pressure of these solutions and cerebrospinal fluid were measured. The cephalad spread of analgesia was greater with higher concentration of dextrose (5 G-Th7.4, 10 G-Th6.0), compared with DW, NS and 2.5 G (Th9.5-9.8). The variation of the maximum level of analgesia was large with DW and NS. The time to complete motor block of both legs were longer with DW and NS than with dextrose containing solutions. The hemodynamic changes after intrathecal injection were small with 2.5 G, DW and NS. Arterial hypotension requiring treatment occurred with 5 G and 10 G. The baricity of spinal anesthetic solution had an important effect on characteristics of the blockade.