Evaluating the depth of the epidural space with the use of ultrasound.

BACKGROUND AND OBJECTIVES The objective of the present study was to evaluate the use of the ultrasound on the determination of the depth of the epidural space. METHODS Sixty patients were included in this prospective study; the L(3)-L(4) space was initially identified by palpation followed by the ultrasound measuring the depth of the epidural space (PU). After the epidural puncture the measurements o the depth (PA) were recorded. The data underwent descriptive statistics, and the concordance correlation coefficient and Bland-Altman analysis, with 95% confidence interval were calculated. RESULTS Analysis of concordance between the palpation and ultrasound methods was 86.6%. Mean values of PU obtained were 4.97 +/- 0.51 cm and PA 4.97 +/- 0.71 cm, and Pearson correlation coefficient of 0.66 while Bland-Altman analysis revealed a mean difference of 0.0035 +/- 0.53 cm with 95% confidence interval between -0.228 and 0.221. CONCLUSIONS The ultrasound is a precise tool to determine the depth of the epidural space.