Table 2 Characteristics in groups according to hemodialysis-related headache

No. of patients

92

84

8

-

Age (year)

59.3 ± 17.5

60.4 ± 17.5

47.9 ± 12.8

0.052

Male

56 (60.9)

51 (60.7)

5 (62.5)

1.000

History of cerebro-vascular diseases

13 (14.1)

13 (15.5)

0 (0.0)

0.503

Dialysis vintage (month)

27.1 (12.0–46.2)

27.1 (12.3–46.2)

27.8 (5.3–44.6)

0.618

URR (%)

65.1 ± 10.9

64.7 ± 11.2

68.5 ± 8.3

0.351

Predialysis blood biochemistry examination

Hemoglobin (g/L)

111.1 ± 20.6

111.1 ± 21.0

111.6 ± 16.7

0.944

Albumin (g/L)

42.1 ± 4.3

41.9 ± 4.4

43.7 ± 2.6

0.270

Sodium (mmol/L)

138.9 ± 3.1

138.9 ± 3.1

138.5 ± 2.9

0.702

Potassium (mmol/L)

4.9 ± 0.6

4.9 ± 0.6

4.9 ± 0.9

0.994

Calcium (mmol/L)

2.2 ± 0.2

2.2 ± 0.2

2.3 ± 0.3

0.937

Magnesium (mmol/L)

1.0 ± 0.2

1.0 ± 0.2

1.1 ± 0.1

0.461

Mean vital signs at hemodialysis-0 h for 12 dialysis sessions

Pulse (beats/min)

81.2 ± 9.4

81.4 ± 9.5

79.5 ± 9.3

0.599

SBP (mmHg)

137.9 ± 15.1

136.7 ± 14.2

150.1 ± 19.6

0.016

DBP (mmHg)

74.6 ± 12.0

73.5 ± 11.1

86.5 ± 15.4

0.050

SpO2 (%)

97.2 ± 0.7

97.2 ± 0.7

97.3 ± 0.6

0.782

Mean hourly variability of vital signs during dialysis

Pulse-ARV

2.9 ± 1.3

2.9 ± 1.3

3.1 ± 1.0

0.647

SBP-ARV

5.6 ± 2.4

5.5 ± 2.3

6.1 ± 2.8

0.495

DBP-ARV

3.7 ± 1.6

3.7 ± 1.5

3.9 ± 2.3

0.673

SpO2-ARV

0.3 ± 0.2

0.4 ± 0.2

0.2 ± 0.1

0.044

Blood gas analysis

pH (%)

742.2 ± 4.9

742.2 ± 4.9

742.5 ± 5.1

0.840

pCO2 (mmHg)

39.0 ± 4.8

38.9 ± 4.7

39.6 ± 5.8

0.693

Base excess (mmol/L)

0.8 ± 1.8

0.8 ± 1.8

1.3 ± 2.1

0.498

HCO3- (mmol/L)

25.4 ± 2.1

25.4 ± 2.1

26.0 ± 1.8

0.382

Sodium (mmol/L)

137.7 ± 1.9

137.7 ± 1.8

136.8 ± 2.2

0.156

Potassium (mmol/L)

3.6 ± 0.5

3.6 ± 0.5

3.3 ± 0.7

0.138

Ion calcium (mmol/L)

1.2 ± 0.1

1.2 ± 0.1

1.2 ± 0.1

0.773

Glucose (mmol/L)

5.9 ± 2.1

5.9 ± 2.1

5.5 ± 2.3

0.553

|OH/DW|^a (%)

132.9 (73.8–211.8)

132.0 (73.8–204.5)

243.5 (74.5–538.2)

0.329