Postoperative cognitive dysfunction and delirium are undesirable consequences of surgery and anesthesia that regrettably do not have consistent predictive markers. Nor do they have reliable prophylactic or treatment methodologies. In an effort to better understand how anesthetic drugs alter the rate of postoperative delirium, Chang et al explore how patients with preoperative cognitive impairment respond to the influence of intraoperative ketamine. Patients aged 65 or older presenting for spine surgery lasting over three hours were assessed and divided into those with and without baseline cognitive impairment. Both groups either received intraoperative ketamine or did not. All patients who received intraoperative ketamine demonstrated an increase in power spectral density via electroencephalographic assessment. However, patients with preoperatively established cognitive impairment displayed a significantly diminished electroencephalographic response to ketamine. Furthermore, this subgroup also suffered an increased incidence of postoperative delirium. What is the interpretation of this finding? An accompanying editorial elegantly describes how disorders of cognition result from both predisposing and precipitating factors. In this case, patients with known cognitive impairment were more likely to endure delirium when exposed to ketamine. Is it possible that ketamine and other drugs could be used as agents to stratify cognitive risk? Should we definitively avoid such drugs as potentiators of cognitive dysfunction? A variety of contextual limitations must be entertained when interpreting the results of this study as summarized in this infographic. These are also elaborated in greater detail in both the primary article as well as its attendant editorial. The reader is encouraged to review both in their entirety for an in-depth scope of understanding.

术后认知功能障碍和谵妄是手术和麻醉的不良后果，遗憾的是没有一致的预测标志物。他们也没有可靠的预防或治疗方法。为了更好地了解麻醉药物如何改变术后谵妄的发生率，Chang 等人探讨了术前认知障碍患者如何应对术中氯胺酮的影响。对 65 岁或以上接受脊柱手术持续超过 3 小时的患者进行评估，并将其分为有和没有基线认知障碍的患者。两组要么接受术中氯胺酮，要么不接受。所有接受术中氯胺酮治疗的患者通过脑电图评估显示功率谱密度增加。然而，术前确定的认知障碍患者对氯胺酮的脑电图反应显着降低。此外，该亚组的术后谵妄发生率也有所增加。对这一发现有何解释？随附的社论优雅地描述了认知障碍是如何由诱发因素和诱发因素引起的。在这种情况下，已知认知障碍的患者在接触氯胺酮时更容易出现谵妄。氯胺酮和其他药物是否有可能被用作对认知风险进行分层的药物？我们是否应该明确避免使用诸如认知功能障碍增强剂之类的药物？在解释本信息图中总结的本研究结果时，必须考虑到各种背景限制。这些也在主要文章及其附带的社论中进行了更详细的阐述。鼓励读者完整地回顾这两篇文章，以获得深入的理解。