Table 1.

Variables used for training of the LR and ANN model.

Variable	Coding
Age	Years
Gender	1: female; 0: male
Height	cm
Weight	kg
BMI	Body mass index
Length (catheter length in the epidural space)	cm
Bolus dose	mL
Total knee replacement (TKA)	0: not TKA∗; 1: TKA
Epidural level (insertion site of EA catheter)	0: above L4; 1: below L4

*Other lower extremities surgery.