Table 1: Patients’ baseline and surgical characteristics.

High hypercapnia group ()Low hypercapnia group ()Control group () value

Age, years0.79
Male, (%)18 (60.0%)17 (56.7%)18 (60.0%)0.96
BMI (kg/m2)0.35
American Society of Anesthesiologists classification, (%)
 II: mild systemic disease20 (66.7%)19 (63.3%)19 (63.3%)0.95
 III: severe systemic disease10 (33.3%)11 (36.7%)11 (36.7%)
Clinical stage, (%)
 I8 (26.7%)7 (23.3%)8 (26.7%)0.99
 II12 (40.0%)13 (43.3%)13 (43.3%)
 III10 (33.3%)10 (33.3%)9 (30.0%)
Distance of tumor from anal verge, (%)
 Upper rectum: 10 to 15 cm9 (30.0%)10 (33.3%)9 (30.0%)0.95
 Middle rectum: 5 to <10 cm11 (36.7%)12 (40.0%)9 (30.0%)
 Lower rectum: <5 cm10 (33.3%)8 (26.7%)11 (36.7%)
PaCO2 (mmHg)0.83
Duration of operation (min)0.66
Total volume of fluids infused (ml)0.52
Blood loss (ml)0.63