Table 3 Demographic characteristics of three individual groups in the observational study

Age, months

25 (14-40)

23 (12-37)

21 (10-34)

Sex, male

23

22

21

Height, cm

83 (73-95)

79 (73-91)

77 (67-92)

Weight, kg

11 (9-14)

10 (9-13)

10 (8-12)

Venous depth, mm

2.9 (2.2-3.6)^a,b

1.7 (1.5-2.1)^b

1.4 (1.1-1.8)

Diameter of target vein, mm

1.8 (1.4-2.0)^a,b

1.4 (1.2-1.6)

1.4 (1.1-1.5)

Systolic blood pressure, mm Hg

93 (84-99)

90 (81-98)

89 (82-97)

Diastolic blood pressure, mm Hg

46 (41-54)

45 (40-55)

43 (38-52)

Trisomy 21

0

2

1

ASA-PS

  PS 1, n = 64

23

20

21

  PS 2, n = 15

5

5

5

  PS 3, n = 16

6

6

4

  PS 4, n = 1

0

0

1

  PS 5, n = 0

0

0

0

Number of trials, times

1 (1-1)

1 (1-1)

1 (1-1)

Success rates, %

97^a,b

68^b

39

Catheterisation times, s

23 (18-33)^a,b

54 (31-180)^b

180 (50-180)