Abstract: Objective To investigate the effects of crystalloid preloading and colloid preloading on hemodynamics and early postoperative cognitive function in the elderly patients undergoing painless colonoscopy. Methods Eighty elderly patients who underwent painless colonoscopy at the First Affiliated Hospital of Anhui Medical University from December 2021 to March 2023 were enrolled in this study. The patients were randomly assigned into the crystalloid group (n=40) and the colloid group (n=40) using a random number table. The crystalloid group received 2 mL/kg sodium lactate ringer’s injection via intravenous infusion 30 minutes before the procedure, while the colloid group received 2 mL/kg of hydroxyethyl starch under the same conditions. The fluid volume was dynamically adjusted based on ultrasound assessment of inferior vena cava respiratory variation (ΔIVC) until ΔIVC ≤ 30%. The mean arterial pressure (MAP) and heart rate (HR) at different time points, as well as awakening time, orientation recovery time, incidence of postoperative dizziness, nausea, thirst, and Montreal Cognitive Assessment (MoCA) scores before and after the operation were compared between the two groups. Results There were no significant differences in MAP and HR between the two groups before and after fluid administration (P>0.05). After anesthesia, the levels of MAP and HR in both groups decreased significantly compared to those before anesthesia (P<0.05), with the crystalloid group showing a greater decline in MAP than the colloid group (P<0.05). Postoperatively, the levels of MAP and HR in both groups increased significantly compared to those after anesthesia (P<0.05), but the level of HR in the crystalloid group was still significantly lower than that before anesthesia (P<0.05). There were no significant differences in awakening time, orientation recovery time, and the incidence rates of postoperative dizziness and nausea between the two groups (P>0.05). However, the colloid group had lower incidence rates of postoperative thirst and of hypotension, and a higher MoCA score than the crystalloid group (P<0.05). Conclusions Compared with crystalloid preloading, colloid preloading before painless colonoscopy in the elderly patients demonstrates a more significant stabilizing effect on hemodynamics, reduces the incidence of postoperative thirst, and exerts a milder impact on early postoperative cognitive function.

Key words: painless colonoscopy, aged, crystalloid, colloid, hemodynamics, postoperative cognitive function