Fig. 3. (A ) Correlation between cerebrospinal fluid (CSF) density and peak sensory block level (ρ= 0.33, P = 0.034). (B ) Inverse correlation between CSF volume and peak sensory block level (ρ=−0.65, P < 0.0001). Although correlation coefficients (ρ) and P values were calculated using Spearman rank correlation, the linear regression lines are presented in these graphs.