Table 1 Baseline characteristics of study subjects according to epidural failure

Age, years

34.4 ± 4.9

34.7 ± 4.8

33.0 ± 5.3

0.003^a

Height, cm

159.1 ± 5.8

159.1 ± 6.0

159.0 ± 4.7

0.841^a

Weight, kg

71.2 ± 12.1

71.6 ± 12.1

69.4 ± 11.9

0.106^a

Body mass index, kg/m²

28.1 ± 4.6

28.3 ± 4.6

27.4 ± 4.3

0.091^a

Previous epidural analgesia

220 (41.2)

163 (37.0)

57 (60.6)

< 0.001^b

Puncture site

0.314^b

L2-3

69 (12.9)

54 (12.3)

15 (16.0)

L3-4

442 (82.8)

369 (83.9)

73 (77.7)

L4-5

23 (4.3)

17 (3.9)

6 (6.4)

Loss of resistance methods

0.885^b

Air

457 (85.6)

377 (85.7)

80 (85.1)

Saline

77 (14.4)

63 (14.3)

14 (14.9)

Catheter depth, cm

5.3 ± 0.7

5.24 ± 0.65

5.31 ± 0.67

0.393^a

Experience of anesthesia provider

0.725^b

Resident

444 (83.1)

367 (83.4)

77 (81.9)

Obstetric anesthesiologist

90 (16.9)

73 (16.6)

17 (18.1)

Emergency surgery

217 (40.6)

185 (42.0)

32 (34.0)

0.152^b

Rupture of membrane

76 (14.2)

65 (14.8)

11 (11.7)

0.439^b

Parity

0.002^b

Nulliparous

224 (41.9)

198 (45.0)

26 (27.7)

Parous

310 (58.1)

242 (55.0)

68 (72.3)

Waiting time

16.2 ± 4.7

16.5 ± 4.7

14.9 ± 4.7

0.002^a