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Table 4 Heart Rate Variability (Frequency Domain and Time Domain Measures)a at Rest and During 15° HUT by diagnosis

From: Autonomic cardiovascular control in older patients with acute infection and delirium: a pilot study of orthostatic stress responses

Characteristic

Rest

15° tilt

Change after 15° tilt

Delirium, n = 5

No delirium, n = 9

Delirium, n = 5

No delirium, n = 9

Delirium, n = 5

No delirium, n = 9

Frequency Domain Measures

 PSD RRI

2400

174

6213

141

− 202

13

(350–30,075)

(16–20,659)

(148–22,462)

(46–19,083)

(−7612–8015)

(− 1576–439)

 LFnuRRI

21

29

23††

39

2

7

(11–62)

(17–57)

(9–65)

(25–62)

(− 28–4)

(−14–16)

 HFnuRRI

79

71

77††

61

−2

−7

(39–89)

(43–83)

(35–91)

(38–75)

(− 4–28)

(− 16–14)

 LFabsRRI (ms2)

419

27

854

29

−44

12

(87–11,813)

(5–5986)

(27–11,579)

(10–5943)

(−234–860)

(− 69–163)

 HFabsRRI (ms2)

1804

88

5267

39

1

4

(86–7371)

(8–14,150)

(87–9161)

(12–11,365)

(− 1150–7071)

(− 2785–130)

 LF/HF ratio

0.3

0.4

0.3

0.5

0

0.1

(0.1–1.6)

(0.2–1.3)

(0.1–1.9)

(0.3–1.4)

(− 0.7–0.3)

(− 0.5–0.8)

Time Domain Measures

 SDNN (ms)

51

25

36

22

−15 b

0

(27–227)

(8–69)

(17–174)

(13–63)

(− 54 - -5)

(− 12–16)

 pNN50 (%)

11

1

9

2

−1

0

(3–68)

(0–36)

(0–86)

(0–20)

(− 10–18)

(− 16–16)

 RMSSD (ms)

36

20

30

30

−9

8

(15–151)

(7–75)

(27–33)

(19–43)

(− 120–19)

(−44–23)

  1. LFnuRRI and HFnuRRI = low frequency and high frequency power in normalized units; LF or HF/(Total Power-VFL(very low frequency) × 100; LFabsRRI and HFabsRRI = power in high frequency and low frequency range in absolute values, respectively; LF/HF = ratio low frequency power/high frequency power; SDNN = Standard Deviation of all NN intervals; pNN50 = NN50 count divided by the total number of all NN intervals; NN50 = number of interval differences of successive NN intervals greater than 50 ms; RMSSD = Root of the Mean of the Sum of Squares of Differences between adjacent NN intervals; NN intervals = normal-to-normal intervals; BRS = Baroreceptor reflex sensibility
  2. p = 0.06, Mann-Whitney test
  3. ††p = 0.08, compared with controls
  4. a Values are medians and total range obtained from registration during sequences of four minutes at rest, and after tilt to 15°. Change after 15° tilt is compared to resting values
  5. bp = 0.01, Mann-Whitney test