Table 3. Exploratory Prognostic Model Predicting the Increase in Number of Segments after Initial Bolus, followed by Either Top-up of Ropivacaine, Saline, or Nothing

Intervention group 1 = epidural top-up with 10 ml ropivacaine 0.75%; Intervention group 2 = epidural top-up with 10 ml normal saline; Intervention group 3 = no epidural top-up given. MNSB first phase = maximum number of segments blocked after the initial bolus of ropivacaine 0.75%.

Gender: 0 = male; 1 = female.

Model: increase of MLSB (number of segments) =β⁰+β¹+ (β²*MNSB phase 1) + (β³*Gender).