Table 1 Comparison of baseline parameters between two groups

Age (year)

84(82–87)

84(81–86)

0.269

Sex(male/female)

15(42.85%)/20(57.15%)

17(48.57%)/18(51.43%)

0.631

Weight (kg)

53.0(50.0–58.0)

55.0(48.0–55.0)

0.995

Height (cm)

156.0(151.0-167.0)

162.0(153.0-167.0)

0.167

BMI (kg/m²)

21.93(21.03–22.64)

21.79(19.65–23.10)

0.267

ASA physical status(II/III)

22(62.85%)/13(37.15%)

20(57.15%)/15(42.85%)

0.626

Fasting hours for solids(h)

14.28(13.70-14.81)

14.06(13.19–14.88)

0.404

Fasting hours for liquids(h)

11.31(10.87–12.08)

2.00(2.00–2.00)

<0.001

Type of surgery

Hip fracture surgery

16(45.71%)

14(40.00%)

0.494

Total knee arthroplasty

10(28.58%)

9(25.71%)

Humerus fracture surgery

9(25.71%)

12(34.29%)

CSA, RLDP, 2 h before surgery (cm²)

5.86(5.13–6.69)

5.52(4.70–6.91)

0.466

CSA, supine, 2 h before surgery (cm²)

3.73(3.41–4.49)

3.83(3.24–4.72)

0.944

Perlas grade 0, 2 h before surgery

26(74.28%)

27(77.14%)

0.727

Perlas grade 1, 2 h before surgery

8(22.86%)

6(17.14%)

Perlas grade 2, 2 h before surgery

1(2.86%)

2(5.72%)