ObjectiveTo explore the effects of CO2 pneumoperitoneum and posture on circulation function for elderly patients with rectal cancer during laparoscopic operation. MethodsRetrospective analysis of clinical data of 48 elderly patients with rectal cancer was performed, and the data included the heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), cardiac output (CO), cardiac index (CI), central venous pressure (CVP), pH, partial pressure of oxygen (PaO2), and partial pressure of carbon dioxide (PaCO2) at before anesthesia (T1), after anesthesia (T2), after the establishment of CO2 pneumoperitoneum (T3), placement in trendelenburg position after operation (T4), 30 minutes after operation (T5), 60 minutes after operation (T6), 90 minutes after operation (T7), and 120 minutes after operation (T8). ResultsThe levels of HR, SBP, DBP, MAP, CO, CI, pH, PaO2, and PaCO2 at 8 time points didn't statistically differed with each other (P>0.05), but the levels of CVP at T7 and T8 time point were significantly higher than those of T1 and T2 time point (P<0.05). ConclusionsDuring laparoscopic operation period for the elderly patients with rectal cancer, the CVP will gradually increase. If the preoperative assessment and administration are done well during peri-operation period, laparoscopic operation is safe for the elderly patients with rectal cancer.