A comparative study of skin to epidural distance at lumbar region using median and paramedian techniques

Background: The median and the paramedian approaches are used to access the epidural space. Median approach is commonly used but can be technically difficult in certain patients. The paramedian approach is the alternative. Success rate during the blind procedure is determined by the skin to epidural distance (SED). SED in turn is affected by patients’ anthropometric characteristics. Prediction of the SED serves to determine the depth of needle advancement in order to improve the success rate. Objectives: The study compared the SED using median vs. paramedian approaches, the time required to access the epidural space, place the catheter, and investigate anthropometric factors which may have influenced this distance among the participants. Materials and Methods: The study was a blinded randomized controlled study. Following ethical approval and informed consent, 60 women scheduled for elective gynecological procedures were allocated to one of the two groups: Group M (median) (30) and Group PM (paramedian) (30). Results: The SED was longer using the PM approach. The mean time it took to gain access was shorter in the PM group. The mean SED increased as the body mass index increased in both groups (P < 0.0001). There was a significant association of anthropometric measurements with the SED using both approaches. Conclusion: The study showed that the SED was longer in the PM group. Also as the patient’s anthropometric measurements increased, so did the SED.