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Table 1 Pre-operative patient characteristics for total group and comparison of those with and without post-operative hyponatraemia

From: Prevalence, risk factors, and complications associated with hyponatraemia following elective primary hip and knee arthroplasty

 

Hyponatraemia (Na < 135 mmol/L) post-operation (n = 217)

No hyponatraemia (Na ≥ 135 mmol/L) post-operation (n = 783)

p-value1

Total group (n = 1000)

Gender (n = 1000)

 Females

135 (62.2%)

453 (57.9%)

0.248

588 (58.8%)

 Males

82 (37.8%)

330 (42.1%)

412 (41.2%)

Age (years) (n = 1000)

73.0 (67.0–78.0)

68.0 (61.0–75.0)

< 0.001

69.0 (62.0–76.0)

Height (cm) (n = 754)

162.2 (155.7–169.5)

165.0 (158.5–173.0)

0.001

164.4 (158.0–172.5)

Weight (kg) (n = 996)

80.0 (67.6–92.0)

83.0 (72.0–95.4)

0.035

82.6 (71.0–94.1)

BMI (kg/m2) (n = 991)

29.8 (26.3–34.0)

29.9 (26.7–33.7)

0.657

29.9 (26.6–22.8)

ASA grade (n = 1000)

 1

7 (3.2%)

54 (6.9%)

0.013

61 (6.1%)

 2

161 (74.2%)

595 (76.0%)

756 (75.6%)

 3/4

49 (22.6%)

134 (17.5%)

183 (18.3%)

Type of arthroplasty (n = 1000)

 Hip

100 (46.1%)

393 (50.2%)

0.391

493 (49.3%)

 Knee

101 (46.5%)

324 (41.4%)

425 (42.5%)

 Uni-knee

16 (7.4%)

66 (8.4%)

82 (8.2%)

Length of stay (n = 1000)

5.0 (3.0–7.0)

3.0 (2.0–4.0)

< 0.001

3.0 (2.0–5.0)

Pre-operative Na (mmol/L) (n = 999)

138.0 (136.0–140.0)

140.0 (138.0–141.0)

< 0.001

139.0 (138.0–141.0)

Blood loss during surgery (ml) (n = 481)+

150.0 (100.0–212.5)

150.0 (100.0–250.0)

0.614

150.0 (100.0–243.0)

24-h blood loss (ml) (n = 989)

1133.7 (869.1–1515.2)

1109.0 (798.5–1402.4)

0.128

1113.7 (810.8–1428.1)

48-h blood loss (ml) (n = 989)

1390.3 (989.0–1817.9)

1264.8 (885.0–1633.9)

0.003

1287.7 (899.9–1675.8)

Duration of operation (min) (n = 1000)

53 (46–64)

55 (47–63)

0.265

54 (47–63)

General anaesthetic (n = 1000)

18 (8.3%)

68 (8.7%)

0.856

86 (8.6%)

Spinal block (n = 1000)

212 (97.7%)

769 (98.2%)

0.580

981 (98.1%)

Peripheral nerve block (n = 1000)

142 (65.4%)

464 (59.3%)

0.099

606 (60.6%)

Transfusion post-operation (n = 961)

44 (20.3%)

50 (6.4%)

< 0.001

94 (9.4%)

Total intravenous fluids on day of surgery (ml) (n = 392)

2500 (2210–3000)

2500 (2110–3000)

0.565

2500 (2140–3000)

Pre-operative haemoglobin (g/L) (n = 894)

131.0 (121.0–141.0)

136 (125.0–145.0)

0.001

134.0 (124.0–144.0)

Fasting glucose (mmol/L) (n = 422)

7.4 (6.4–8.6)

6.5 (5.9–7.6)

< 0.001

6.7 (5.9–7.8)

  1. Median (IQR) used for continuous variables and n (%) used for categorical variables
  2. Chi-square analysis used to compare categorical variables and Mann-Whitney U test used to compare continuous variables
  3. 1p-value comparing those with post-operative hyponatraemia (Na < 135 mmol/L) and those with normal sodium values (Na ≥ 135 mmol/L) post-operatively
  4. +Blood loss during surgery was only available in hip replacement patients
  5. For pre-operative Na, when available, Na on the day of surgery was taken, if this was not available, pre-assessment Na was taken
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Perioperative Medicine

ISSN: 2047-0525