Table 8 Multivariable analysis showing factors associated with failed spinal anesthesia (N = 532)

Urgency of operation

Emergency

91(43.1%)

120(56.9%)

7.935(4.94–12.75)

7.014(4.480-12.717)

0.00001

Elective

28(8.7%)

293(91.3%)

(1)

Dose of bupivacaine

5–10 mg

47(34.1%)

91(65.9%)

3.228(2.31–3.92)

3. 021(1.262–10.232)

0.017

11-18 mg

50(20.1%)

199(79.9%)

1.57(1.35–1.83)

0.163(0.262–3.083)

0.671

19–25 mg

20(13.8%)

125(86.2%)

1

work experience of anesthetist

< 2 year

57(55.9%)

45(44.1%)

20.7(13.23–25.9)

3.110(1.692–5.716)

0.000258

2–5 year

47(27.6%)

123(72.4%)

6.24(2.086-6.30)

1.176(1.057–2.550)

0.003

> 5 year

15 (5.8%)

245(94.2%)

1

CSF characteristics

Bloody

45(69.2%)

20(30.8%)

11.95(6.8-22.24)

8.488(2.529–18.491)

0.000314

Clear

74(15.8%)

393(84.2%)

1

Baricity of local anesthetics

Hyperbaric

61(70.9%)

25(29.1%)

16.32(3.08–25.29)

3.287 (3.196–8.213)

0.00001

Isobaric

58(13.0%)

388(87.0%)

1

Use of adjuvants

No

114(30.0%)

266(70.0%)

5.494(5.03–31.55)

5.250(2.619–14.186)

0.000218

Yes

11(7.2%)

141(92.8%)

1