Xu L, Hu Z, Shen J, McQuillan PM. Effects of Ginkgo biloba extract on cerebral oxygen and glucose metabolism in elderly patients with pre-existing cerebral ischemia. Complement Ther Med. 2015;23(2):220-225.
Patients (n = 60; aged > 60 years) with vertebrobasilar artery insufficiency diagnosed via transcranial Doppler ultrasonography and scheduled for elective total hip replacement surgery participated in this study conducted at Zhejiang University Hospital; Hangzhou, China. Patients were excluded if they had diabetes mellitus, cardiovascular or other cerebrovascular disease, hyperlipidemia, osteoarthritis, neurological or psychiatric disease, or abnormal renal or hepatic function; were taking multiple medications for other diseases; had any known sensitivity to study medications; were hearing or vision impaired or illiterate; had mental retardation; previously used sedatives or antidepressants; had a history of alcoholism; or had anesthesia in the past.
Patients received no anesthetic premedication and no post-operative intravenous anesthesia or muscle relaxant reversal medications. After anesthesia was induced, saline (placebo) or 1 mg/kg ginkgo leaf extract (Shineway Pharmaceutical Co.; Hebei, China) (20 ml extract diluted with normal saline to 250 mL) was intravenously infused over 30 minutes prior to surgical incision. Arterial and internal jugular venous blood samples were collected preoperatively, before surgical incision, at the end of surgery, and on post-op day 1 to measure blood gases and glucose concentrations. Arterial oxygen content (CaO2), jugular venous oxygen content (CjvO2) and oxygen saturation (SjvO2), arteriovenous oxygen content difference (Da-jvO2, difference between arterial and venous O2 content), and cerebral oxygen extraction rate (CEO2) were calculated to determine cerebral oxygen supply and demand balance. Arteriovenous glucose and lactate content differences (Da-jvGlu and Da-jvLac) were also calculated.
In the placebo group, at the end of surgery and on post-op day 1, there was a significant increase in SjvO2 and Da-jvLac, and there was a significant decrease in CEO2 (P < 0.05 for all) compared with baseline. The increase in lactate content indicates ischemia (lack of oxygen). In the ginkgo group, at the end of surgery and on post-op day 1, there was a significant increase in SjvO2 and CjvO2, and there was a significant decrease in Da-jvO2 and CEO2 (P < 0.05 for all) compared with baseline. The lack of an increase in lactate content indicates that ginkgo may have a protective effect by reducing lactic acid accumulation.
Compared with the placebo group, the ginkgo group had a significant increase in CjvO2 and SjvO2, and a significant decrease in CEO2, Da-jvO2, and Da-jvLac at the end of surgery and on post-op day 1 (P < 0.05 for all).
There were no significant differences between groups in CaO2 or Da-jvGlu. There were no significant differences between groups in heart rate, mean arterial pressure, respiratory rate, end-tidal carbon dioxide partial pressure, hemoglobin oxygen saturation, hemoglobin, arterial blood carbon dioxide partial pressure, or heart function. The incidence of adverse events (rate not reported) was similar between groups.
In summary, pre-operative intravenous ginkgo had a positive effect on cerebral oxygen supply and demand; it improved cerebral oxygen supply, decreased cerebral oxygen extraction rate and consumption, and reduced cerebral oxygen metabolic rate. Ginkgo had no significant effect on cerebral glucose metabolism. The data support the hypothesis that ginkgo infusion may provide neuroprotection in patients with pre-existing cerebral insufficiency who are undergoing surgery with general anesthesia. Limitations of the study are that long-term safety and efficacy outcomes were not evaluated. The authors conclude, "Further clinical studies in humans examining the influence of Ginkgo biloba extract on oxygen metabolism are needed."
—Heather S. Oliff, PhD