The distance from the skin to the epidural and subarachnoid spaces in parturients scheduled for caesarean section.

BACKGROUND

The purpose of this study was to measure the skin to epidural space distance (SED), the skin to subarachnoid space distance (SSD) and the epidural to subarachnoid space distance (ESD) at the L3-4 interspace in parturients scheduled for caesarean section (CS) and to investigate whether any correlations exist between these distances and various physical and anthropometric parameters.

METHODS

This study consisted of 332 parturients scheduled for CS. The epidural space was identified by noting the loss of resistance to air at the L3-4 intervertebral space with a Tuohy needle, thus permitting measurement of the SED. The spinal needle was introduced through the Tuohy needle and, after identification of the subarachnoid space, was locked in the epidural needle. The distance between the tip of the Tuohy needle and tip of spinal needle (ESD) was recorded. This number was added to the SED to obtain the SSD value.

RESULTS

Mean values ± standard deviations for SED, SSD and ESD were 5.6 ± 1.6 cm, 6.5 ± 1.2 cm and 0.9 ± 0.5 cm, respectively. Statistically significant correlations were observed between SED, SSD and ESD with body mass index and body weight of the parturients, as well as between the SED and the parturient's height. Furthermore, a significant negative correlation was observed between the ESD and gestational age. Finally, a significant correlation existed between the SSD and ESD.

CONCLUSION

Measurements of SED, SSD and ESD in parturients and the correlations between these distances to various physical and anthropometric parameters may be of potential value for combined spinal-epidural anesthesia (CSEA) in parturients scheduled for CS.