Lee In Ho, Culley Deborah J, Baxter Mark G, Xie Zhongcong, Tanzi Rudolph E, Crosby Gregory
Department of Anesthesiology, Korea University Guro Hospital, Seoul, Republic of Korea.
Anesth Analg. 2008 Oct;107(4):1211-5. doi: 10.1213/ane.0b013e31817ee879.
We have previously demonstrated that aged rats have persistent impairment of spatial memory after sedation with nitrous oxide or general anesthesia with isoflurane-nitrous oxide. Propofol has different receptor mechanisms of action and a favorable short-term recovery profile, and it has been proposed that propofol is devoid of enduring effects on cognitive performance. No studies have investigated this question in aged subjects, however, so we designed an experiment to examine the long-term effects of propofol anesthesia on spatial working memory.
Eighteen-mo-old rats were randomized to 2 h of 100% oxygen-propofol anesthesia (n=11) or to a control group that breathed 100% oxygen (n=10). Propofol was administered by continuous infusion via a tail vein catheter. Rats breathed spontaneously and rectal temperature was maintained. Mean arterial blood pressure was measured noninvasively and a venous blood gas was obtained just before discontinuation of propofol. After a 2-day recovery, spatial working memory was assessed for 14 days using a 12-arm radial maze. The number of total errors, number of correct choices to first error, and time to complete the maze was recorded and analyzed using a repeated measure analysis of variance (ANOVA), with P<0.05 being considered statistically significant.
The average propofol infusion rate was 0.6+/-0.1 mg.kg (-1).min(-1), a rate corresponding to a 50% effective concentration dose in adult rats. Mean arterial blood pressure during anesthesia was 100+/-2 mm Hg and venous blood gases remained in the normal range. There was no difference between the control and previously anesthetized rats on any measure of radial arm maze performance, indicating propofol anesthesia produces no lasting impairment in spatial working memory in aged rats.
In aged rats, propofol anesthesia is devoid of the persistent memory effects observed with other general anesthetics in this model. Thus, while it appears that the state of general anesthesia is neither necessary nor sufficient for development of postanesthetic memory impairment, the choice of anesthetics may play a role in late cognitive outcome in the aged.
我们之前已经证明，老年大鼠在接受氧化亚氮镇静或异氟烷 - 氧化亚氮全身麻醉后，空间记忆存在持续性损伤。丙泊酚具有不同的受体作用机制和良好的短期恢复情况，并且有人提出丙泊酚对认知表现没有持久影响。然而，尚无研究在老年受试者中探讨过这个问题，因此我们设计了一项实验来研究丙泊酚麻醉对空间工作记忆的长期影响。
将18月龄大鼠随机分为两组，一组接受2小时的100%氧气 - 丙泊酚麻醉（n = 11），另一组作为对照组，呼吸100%氧气（n = 10）。丙泊酚通过尾静脉导管持续输注给药。大鼠自主呼吸，维持直肠温度。无创测量平均动脉血压，并在停止丙泊酚给药前采集静脉血气。经过2天的恢复后，使用12臂放射状迷宫对空间工作记忆进行14天的评估。记录并分析总错误数、首次出错前的正确选择数以及完成迷宫的时间，采用重复测量方差分析（ANOVA），P < 0.05被认为具有统计学意义。
丙泊酚的平均输注速率为0.6±0.1 mg·kg⁻¹·min⁻¹，该速率相当于成年大鼠的50%有效浓度剂量。麻醉期间平均动脉血压为100±2 mmHg，静脉血气保持在正常范围内。在放射状迷宫表现的任何测量指标上，对照组和先前接受麻醉的大鼠之间均无差异，这表明丙泊酚麻醉对老年大鼠的空间工作记忆没有产生持久损伤。
在老年大鼠中，丙泊酚麻醉没有出现该模型中其他全身麻醉药所观察到的持续性记忆效应。因此，虽然全身麻醉状态似乎对于麻醉后记忆损伤的发生既非必要条件也非充分条件，但麻醉药的选择可能在老年人后期认知结果中起作用。
