Comparison of anesthetic solutions used in lumbar and caudal peridural anesthesia

Clinical observations on peridural anesthesia were made in 466 patients. The spread of various concentrations of anesthetics injected into the lumbar and caudal peridural space were followed by plotting analgesia-time profiles. Onset of anesthesia and the volume required to provide one dermatome of anesthesia varied little among different anesthetics given in different concentrations. The sequence of appearance of analgesia was also similar, with longer times being required to block larger roots. Quality of anesthesia was judged by the penetration of anesthestic solutions into the largest spinal nerve root (S1); rate of penetration depended on the type of drug and concentration. No drug concentration combination included all the ideal characteristics for block: minimal mass of anesthetic, maximum spread, long duration (minutes of anesthesia per milligram of drugs per segment), low incidence of failure, and fast stabilization time. However, depending on the surgical needs and the characteristics of the patients, some drugs and concentrations may be preferred. Stabilization and onset were slower and drug requirements larger for caudal than for lumbar peridural anesthesia.