Table 2 Repeated-measures analysis of the effects of position and the position-by-time interaction on physiological parameters.

From: Cerebrovascular responses to a 90° tilt in healthy neonates

rcSO2 (%)

Mean

±SD

β

SE

z

95% CI

p

 Position

 Supine

80.0

6.3

Ref

-

-

-

-

 Sitting

78.9

6.1

−0.75

0.15

−5.12

(−1.04, −0.47)

<0.001*

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(79.8, 79.3)

(0.9, 0.9)

Ref

-

-

-

-

 2

(80.1, 78.5)

(0.9, 0.9)

0.18

0.15

1.19

(−0.11, 0.47)

0.23

 3

(80.2, 78.9)

(0.9, 0.9)

0.16

0.15

1.05

(−0.13, 0.45)

0.29

 Position-by-Time

-

-

-

-

-

-

<0.001*

SpO2 (%)

       

 Position

 Supine

97.3

1.7

Ref

-

-

-

-

 Sitting

97.4

1.5

0.31

0.06

4.77

(0.18, 0.44)

<0.001*

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(97.3, 97.7)

(0.2, 0.2)

Ref

-

-

-

-

 2

(97.5, 97.3)

(0.2, 0.2)

0.1

0.07

1.55

(−0.03, 0.23)

0.12

 3

(97.2, 97.0)

(0.2, 0.2)

−0.33

0.07

−5.08

(−0.46, −0.21)

<0.001*

 Position-by-Time

-

-

-

-

-

-

<0.001*

HR (bpm)

       

 Position

 Supine

132.7

12.6

Ref

-

-

-

-

 Sitting

133.7

13.2

0.16

0.47

0.35

(−0.75, 1.08)

0.73

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(132.8, 133.2)

(1.9, 1.9)

Ref

-

-

-

-

 2

(132.6, 134.4)

(1.9, 1.9)

−0.46

0.47

-0.97

(−1.38, 0.47)

0.33

 3

(132.6, 133.4)

(1.9, 1.9)

−0.13

0.47

-0.29

(−1.06, 0.79)

0.78

 Position-by-Time

-

-

-

-

-

-

0.002*

MBP (mmHg)

       

 Position

 Supine

61.4

11.8

Ref

-

-

-

-

 Sitting

62.6

11.5

4.88

0.37

13.24

(4.15, 5.60)

<0.001*

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(58.9, 63.4)

(1.7, 1.7)

Ref

-

-

-

-

 2

(63.5, 63.1)

(1.7, 1.7)

5.25

0.37

14.14

(4.52, 5.98)

<0.001*

 3

(61.7, 61.1)

(1.7, 1.7)

3.53

0.37

9.47

(2.79, 4.26)

<0.001*

 Position-by-Time

-

-

-

-

-

-

<0.001*

BR (BPM)

       

 Position

 Supine

35.8

5.7

Ref

-

-

-

-

 Sitting

33.2

4.2

−3.59

0.4

−8.94

(−4.37, −2.80)

<0.001*

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(35.6, 32.4)

(0.7, 0.7)

Ref

-

-

-

-

 2

(36.7, 33.3)

(0.7, 0.7)

1.11

0.4

2.75

(0.32, 1.90)

0.006*

 3

(35.2, 33.9)

(0.7, 0.7)

−0.74

0.41

−1.81

(−1.53, 0.60)

0.07

 Position-by-Time

-

-

-

-

-

-

<0.001*

cFTOE

       

 Position

 Supine

0.18

0.07

Ref

-

-

-

-

 Sitting

0.19

0.07

0.01

0.002

6.65

(0.007, 0.014)

<0.001*

 Time

(Supine/Sitting)

(Supine/Sitting)

     

 1

(0.18, 0.19)

(0.01, 0.01)

Ref

-

-

-

-

 2

(0.18, 0.19)

(0.01, 0.01)

−0.0003

0.002

−0.19

(−0.003, 0.003)

0.85

 3

(0.17, 0.19)

(0.01, 0.01)

−0.004

0.002

−2.4

(−0.007, −0.001)

0.016*

 Position-by-Time

-

-

-

-

-

-

0.003*

  1. Mixed-model repeated-measures analysis determined the effects of position (supine, sitting), time (1, 2, 3), and the position-by-time interaction on each physiological parameter. Covariates in the model were sex, ethnicity, postconceptional age, and sleep-state. rcSO2 = regional cerebral oxygen saturation; SpO2 = arterial peripheral oxygen saturation. If significance was achieved under position, parameters were significantly different from the supine position. If significance was achieved under time, parameters were significantly different from the first tilt. If significance was achieved under position-by-time, there was a significant position-by-time interaction on the parameters.
  2. HR heart rate, MBP mean blood pressure, BR breathing rate, cFTOE cerebral fractional tissue oxygen extraction.
  3. *2-sided p ≤ 0.05.
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