Table 1 Comparison between higher bicarbonate and lower bicarbonate

Age, year

72.7 ± 5.8

74.0 ± 6.4

< 0.01*

Sex

0.111

 Male

 Female

563 (61.5%)

353 (38.5%)

319 (57.3%)

238 (42.7%)

BMI, kg/m²

22.4 ± 3.2

22.7 ± 3.4

0.076

Smoking

329 (35.9%)

209 (37.5%)

0.535

Drinking

268 (29.3%)

167 (30.0%)

0.768

Hypertension

334 (36.5%)

220 (39.5%)

0.244

T2DM

160 (17.5%)

99 (17.8%)

0.881

CHD

69 (7.5%)

61 (11.0%)

0.025*

Open surgery

75 (8.2%)

104 (18.7%)

< 0.01*

Tumor location

< 0.01*

 Colon

411 (44.9%)

343 (61.6%)

 Rectum

505 (55.1%)

214 (38.4%)

TNM stage

0.508

 I

158 (17.2%)

88 (15.8%)

 II

397 (43.3%)

231 (41.5%)

 III

319 (34.8%)

205 (36.8%)

 IV

42 (4.7%)

33 (5.9%)

Tumor size

< 0.01*

 < 5 cm

552 (60.3%)

282 (50.6%)

 ≥ 5 cm

364 (39.7%)

275 (49.4%)

Operation time (min)

216.3 ± 80.0

221.2 ± 85.9

0.260

Blood loss (mL)

84.3 ± 123.6

103.0 ± 140.5

< 0.01*

Hospital stay (day)

10.8 ± 9.4

11.4 ± 7.7

0.184

Retrieved lymph nodes

15.5 ± 8.0

15.1 ± 6.4

0.260

Overall complications

206 (22.5%)

160 (28.7%)

< 0.01*

Major complications

23 (2.5%)

22 (3.9%)

0.120

30-day deaths

0 (0.0%)

7 (1.3%)

< 0.01*