BACKGROUND The relationship between intraoperative physiology and postoperative stroke is incompletely understood. Preliminary data suggest that either hypo- or hypercapnia coupled with reduced cerebrovascular inflow (e.g., due to hypotension) can lead to ischemia. This study tested the hypothesis that the combination of intraoperative hypotension and either hypo- or hypercarbia is associated with postoperative ischemic stroke. METHODS We conducted a retrospective, case-control study via the Multicenter Perioperative Outcomes Group. Noncardiac, nonintracranial, and nonmajor vascular surgical cases (18 yr or older) were extracted from five major academic centers between January 2004 and December 2015. Ischemic stroke cases were identified via manual chart review and matched to controls (1:4). Time and reduction below key mean arterial blood pressure thresholds (less than 55 mmHg, less than 60 mmHg, less than 65 mmHg) and outside of specific end-tidal carbon dioxide thresholds (30 mmHg or less, 35 mmHg or less, 45 mmHg or greater) were calculated based on total area under the curve. The association between stroke and total area under the curve values was then tested while adjusting for relevant confounders. RESULTS In total, 1,244,881 cases were analyzed. Among the cases that screened positive for stroke (n = 1,702), 126 were confirmed and successfully matched with 500 corresponding controls. Total area under the curve was significantly associated with stroke for all thresholds tested, with the strongest combination observed with mean arterial pressure less than 55 mmHg (adjusted odds ratio per 10 mmHg-min, 1.17 [95% CI, 1.10 to 1.23], P < 0.0001) and end-tidal carbon dioxide 45 mmHg or greater (adjusted odds ratio per 10 mmHg-min, 1.11 [95% CI, 1.10 to 1.11], P < 0.0001). There was no interaction effect observed between blood pressure and carbon dioxide. CONCLUSIONS Intraoperative hypotension and carbon dioxide dysregulation may each independently increase postoperative stroke risk. EDITOR’S PERSPECTIVE

中文翻译：

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二氧化碳、血压和围手术期卒中：回顾性病例对照研究。

背景技术术中生理学与术后卒中之间的关系尚不完全清楚。初步数据表明，低碳酸血症或高碳酸血症加上脑血管流入减少（例如，由于低血压）可导致缺血。这项研究检验了术中低血压和低碳酸血症或高碳酸血症的组合与术后缺血性卒中相关的假设。方法 我们通过多中心围手术期结果组进行了一项回顾性病例对照研究。2004 年 1 月至 2015 年 12 月期间，从五个主要学术中心提取非心脏、非颅内和非大血管手术病例（18 岁或以上）。通过手动图表审查识别缺血性卒中病例，并与对照进行匹配 (1:4)。低于关键平均动脉血压阈值（小于 55 mmHg、小于 60 mmHg、小于 65 mmHg）和特定呼气末二氧化碳阈值（30 mmHg 或更低、35 mmHg 或更低、45 mmHg 或更大）是根据曲线下的总面积计算的。然后测试中风与曲线下总面积值之间的关联，同时调整相关混杂因素。结果 总共分析了 1,244,881 例病例。在中风筛查呈阳性的病例中（n = 1,702），有 126 例得到确诊，并与 500 名相应对照成功匹配。对于所有测试阈值，曲线下总面积与卒中显着相关，平均动脉压低于 55 mmHg 时观察到的最强组合（每 10 mmHg-min 调整后的比值比，1.17 [95% CI，1.10 至 1.23]，P < 0.0001）和呼气末二氧化碳 45 mmHg 或更高（每 10 mmHg-min 调整后的比值比，1.11 [95% CI，1.10 至 1.11]，P < 0.0001）。没有观察到血压和二氧化碳之间的相互作用。结论术中低血压和二氧化碳失调可能各自独立地增加术后卒中风险。编辑的观点