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.