t study at a tertiary medical center from July 2021 to November 2023. Eligible patients were ≥18 undergoing isolated coronary bypass (CAB) surgery with the use of cardiopulmonary bypass (CPB). Cardiac output indexed to body surface area (CI) was continuously recorded at 5-second intervals throughout surgery using a US Food and Drug Administration (FDA)-approved noninvasive monitor from the arterial blood pressure waveform. Mean arterial blood pressure (MAP) and central venous pressure (CVP) were also analyzed. Low CI was defined as <2 L/min/m2 and low MAP as <65 mm Hg. We calculated time with low CI for each patient for the entire surgery, pre-CPB and post-CPB periods, and the proportion of time with low CI and normal MAP. We used Pearson correlation to evaluate the relationship between CI and MAP and paired Wilcoxon rank sum tests to assess the difference in correlations of CI with MAP before and after CPB. RESULTS: In total, 101 patients were analyzed (age [standard deviation, SD] 64.8 [9.8] years, 25% female). Total intraoperative time (mean [SD]) with low CI was 86.4 (62) minutes, with 61.2 (42) minutes of low CI pre-CPB and 25.2 (31) minutes post-CPB. Total intraoperative time with low CI and normal MAP was 66.5 (56) minutes, representing mean (SD) 69% (23%) of the total time with low CI; 45.8 (38) minutes occurred pre-CPB and 20.6 (27) minutes occurred post-CPB. Overall, the correlation (mean [SD]) between CI and MAP was 0.33 (0.31), and the correlation was significantly higher pre-CPB (0.53 [0.32]) than post-CPB (0.29 [0.28], 95% confidence interval [CI] for difference [0.18–0.34], P < .001); however, there was substantial heterogeneity among participants in correlations of CI with MAP before and after CPB. Secondary analyses that accounted for CVP did not alter the correlation between CI and MAP. Exploratory analyses suggested duration of low CI (C <2 L/min/m2) was associated with increased risk of postoperative acute kidney injury (odds ratios [ORs] = 1.09; 95% CI; 1.01–1.13; P = .018). CONCLUSIONS: In a prospective cohort of patients undergoing CAB surgery, low CI was common even when blood pressure was normal. CI and MAP were correlated modestly. Correlation was higher before than after CPB with substantial heterogeneity among individuals. Future studies are needed to examine the independent relation of low CI to postoperative kidney injury and other adverse outcomes related to hypoperfusion....

中文翻译：

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心脏手术血压正常期心脏指数低的发生：一项使用连续无创心输出量监测的前瞻性队列研究


t 2021 年 7 月至 2023 年 11 月在三级医疗中心学习。符合条件的患者为 ≥18 接受体外循环 （CPB） 的孤立冠状动脉搭桥 （CAB） 手术。在整个手术过程中，使用美国食品和药物管理局 （FDA） 批准的无创监测仪从动脉血压波形中以 5 秒的间隔连续记录以体表面积 （CI） 为索引的心输出量。还分析了平均动脉血压 （MAP） 和中心静脉压 （CVP）。低 CI 定义为 <2 L/min/m2，低 MAP 定义为 <65 mm Hg。我们计算了每位患者在整个手术、CPB 前和 CPB 后期间的低 CI 时间，以及低 CI 和 MAP 正常的时间比例。我们使用 Pearson 相关性来评估 CI 和 MAP 之间的关系，并使用配对 Wilcoxon 秩和检验来评估 CPB 前后 CI 与 MAP 相关性的差异。结果： 共分析了 101 例患者 （年龄 [标准差，SD] 64.8 [9.8] 岁，25% 为女性）。低 CI 的总术中时间 （平均值 [SD]）为 86.4 （62） 分钟，其中 CPB 前低 CI 为 61.2 （42） 分钟，CPB 后为 25.2 （31） 分钟。低 CI 和 MAP 正常的术中总时间为 66.5 （56） 分钟，占低 CI 总时间的平均 （SD） 69% （23%）;45.8 （38） 分钟发生在 CPB 之前，20.6 （27） 分钟发生在 CPB 之后。总体而言，CI 和 MAP 之间的相关性 （平均值 [SD]）为 0.33 （0.31），并且相关性显著高于 CPB 前 （0.53 [0.32]） （0.29 [0.28]，差异的 95% 置信区间 [CI] [0.18-0.34]，P < .001）;然而，参与者在 CPB 前后 CI 与 MAP 的相关性存在很大异质性。 考虑 CVP 的二次分析不会改变 CI 和 MAP 之间的相关性。探索性分析表明，低 CI 持续时间 （C <2 L/min/m2） 与术后急性肾损伤风险增加相关 （比值比 [ORs] = 1.09;95% CI;1.01-1.13;P = .018）。结论： 在接受 CAB 手术的前瞻性患者队列中，即使血压正常，低 CI 也很常见。CI 和 MAP 呈适度相关性。CPB 前后的相关性高于 CPB 后，个体间存在很大异质性。需要未来的研究来检验低 CI 与术后肾损伤和其他与低灌注相关的不良结局的独立关系。