Table 1 Demographic and clinical characteristics of patients

Sex(male/female)

13/12

7/5

6/7

0. 695

Age(years)

70. 2 ± 3. 9

69. 9 ± 4. 3

70. 5 ± 3. 6

0. 737

Weight(kg)

64. 9 ± 10. 9

64. 5 ± 11. 4

65. 2 ± 10. 8

0. 864

Height(cm)

163. 8 ± 8. 3

166. 0 ± 8. 8

161. 9 ± 7. 6

0. 222

Body mass index(kg/m²)

24. 0 ± 3. 2

23. 4 ± 3. 2

24. 5 ± 3. 2

0. 389

ASA physical status

(I/II/III)

0/17/8

0/9/3

0/8/5

0. 673

Types of surgery

Gastrointestinal

9

4

5

Urinary

7

5

2

Hepatobiliary

3

0

3

Spine

4

2

2

Neurosurgery

1

0

1

Oral surgery

1

0

1

complicating disease

Hypertension

16

6

10

0. 226

Diabetes

6

2

4

0. 645

Coronary heart disease

5

0

5

0. 039^*

Anaemia

2

1

1

> 0. 999

Abnormal liver function

4

3

1

0. 322