Effects of goal directed fluid therapy on brain metabolism and brain protection in elderly patients undergoing craniocerebral surgery

Objective To investigate the mechanism of goal directed fluid therapy on brain metabolism and brain protection in elderly patients undergoing craniocerebral surgery. Methods The clinical data of 80 elderly patients undergoing craniocerebral surgery in Kaiping Hospital of Tangshan from January 2015 to December 2016 were retrospectively analyzed. Among them, 40 patients (observation group) received goal directed fluid therapy, and another 40 patients (control group) received routine surgery. The heart rate (HR), mean arterial pressure (MAP) and cardiac output index (CI) levels as well as changes in brain metabolism and blood lactate levels were detected before induction of anaesthesia (T1), tracheal intubation immediately (T2), incision of dural immediately (T3), incision of dura after 1 h (T4) and the end of surgery (T5) between the two groups. Results The urine volume, total infusion volume, and colloidal volume were (1 602.7±305.3) mL, (3 215.8±442.8) mL, and (2 028.1±345.2) mL in the observation group, respectively, which were significantly higher than those in the control group [(1 105.5±256.2) mL, (2 604.3±352.6) mL, (855.6±278.6) mL], but the amount of crystals was (1 142.5±242.5) mL, which was significantly lower than that of the control group[(2 102.7±102.8) mL], with statistical differences between the two groups (all P values<0.05). Compared with the time point of T1, the HR levels in the two groups at T2, T3, T4 and T5 were significantly decreased, and the MAP level was significantly decreased at T2, but increased at T4 and T5, and the CI level was significantly elevated at T4 and T5. At the time-point of T4 and T5, the MAP and CI levels in the observation group were significantly higher than those in the control group, and there was a statistically significant difference between the two groups (all P values<0.05). Compared with time-point of T1, the levels of CaO2 and CjvO2 were both decreased significantly in the two groups, and the CaO2 levels in the observation group were significantly higher than those in the control group at T2, T3, T4 and T5, but the CjvO2 level was significantly lower than that of the control group, with statistically significant difference between the two groups (all P values<0.05). Compared with time point of T1, the arterial lactate (aLac) levels in the two groups increased significantly from T3, T4 and T5, and the observation group was significantly lower than the control group, and meanwhile, the aLac levels were significantly increased in the two groups from T3, T4 and T5, and the vein lactate(vLac) levels in the observation group from T2 , T3, T4 and T5 were significantly lower than those in the control group. However, when compared with time-point of T1, the brain lactate production rate (LacPR) levels in the two groups from T2 , T3, T4 and T5 were significantly decreased, and there was a statistically significant difference between the two groups (all P values<0.05). Conclusions Goal directed fluid therapy can effectively improve the cardiac preload and brain metabolism in the elderly patients undergoing craniocerebral surgery, and the main mechanism may be related to the reduction of lactate production in brain. Key words: Fluid therapy; Aged; Craniocerebral surgery; Goal-directed fluid therapy; Brain metabolism; Hemodynamics