Evaluating the association between mean arterial blood pressure through the first 24 hours after cardiac surgery and postoperative acute kidney injury

在美国，每年约有50万患者接受心脏手术。急性肾 损伤（AKI）使25%的病例复杂化，并与住院时间、成本 进展为慢性肾病和死亡。术后早期血压不足 一段时间是心脏手术后AKI的可能原因，可以通过更高的目标有效解决 平均动脉压（MAP）。目前的实践通常以MAP ≥ 65 mmHg为目标， 但是这是否是最小化肾损伤的最佳目标压力尚不清楚。 我们研究的长期目标是尽量减少成人心脏手术后AKI的发生率 通过在这种情况下确定最佳术后目标MAP。建议的目标 队列研究是利用现有的每分钟术后MAP数据， 手术以确定术后MAP阈值，超过该阈值AKI的风险会增加，并且，单独地， 探索早期术后MAP与其他非肾脏损害之间的相关性证据， 在临床试验中选择最合适的目标MAP时需要考虑。 我们的具体目标是：1a）评估在多个项目中花费的时间之间的关联 绝对MAP范围频带（例如，65 - 69，70 - 74 mmHg）至心脏手术后前24小时（h） 和AKI; 1b）评估在多个离散MAP范围中的每一个中花费的时间之间的关联。 由术前基线MAP的百分比变化定义的条带（例如，-6至-10%，-11至-15%） 2a）评估在心脏手术后的前24小时内与AKI之间的关联; 心脏手术后前24小时内的多个绝对MAP范围带中的每一个， 不良结局包括谵妄、中风、输血和计划外手术再灌注。 2b）评估在多个离散MAP范围中的每一个中花费的时间之间的关联。 通过心脏起搏后前24小时内相对于术前基线MAP的百分比变化定义的条带 手术和指定的非肾脏不良结局。这些目标将通过回归来实现 根据术后24小时内的每分钟MAP数据建立的纵向MAP曲线模型， 接受心脏手术的患者。结合经验证的结局数据，并针对关键的潜在 混杂协变量适用于每个结果，我们将检验假设： 在术后24小时内，MAP处于多个离散范围带的每一个中（相对于参考MAP 范围带）与AKI和其他非肾脏结局的几率增加相关。我们 结果将提供关键的证据，以指导数据驱动选择最合适的目标MAP， 未来的试验测试这种替代目标MAP减少AKI和改善患者结局的有效性 心脏手术后

Approximately half a million patients undergo cardiac surgery in the United States each year. Acute kidney injury (AKI) complicates 25% of cases, and is associated with increased hospital length of stay, cost, progression to chronic kidney disease and death. Inadequate blood pressure during the early postoperative period is a likely contributor to AKI after cardiac surgery that may be effectively addressed with a higher target mean arterial pressure (MAP) during this period. Current practice typically targets a MAP ≥65 mmHg after cardiac surgery but whether this is the optimal target pressure for minimizing kidney injury is unknown. The long-term objective of our research is to minimize the incidence of AKI after adult cardiac surgery through identification of an optimal postoperative target MAP in this setting. The objective of the proposed cohort study is to harness existing minute-by-minute postoperative MAP data from patients undergoing cardiac surgery to identify a postoperative MAP threshold beyond which the risk of AKI increases and, separately, explore for evidence of association between early postoperative MAP and other non-renal harm that may also need consideration in selecting the most appropriate target-MAP for testing in a clinical trial. Our Specific Aims are to: 1a) Evaluate the association between time spent in each of multiple absolute MAP range-bands (e.g., 65-69, 70-74 mmHg) through the first 24 hours(h) after cardiac surgery and AKI; 1b) Evaluate the association between time spent in each of multiple discrete MAP range- bands defined by the percent change from preoperative baseline MAP (e.g., -6 to -10%, -11 to -15%) through the first 24h after cardiac surgery and AKI; 2a) Evaluate the association between time spent in each of multiple absolute MAP range-bands through the first 24h after cardiac surgery and non-renal adverse outcomes including each of delirium, stroke, blood transfusion and unplanned surgical re- exploration; 2b) Evaluate the association between time spent in each of multiple discrete MAP range- bands defined by percent change from preoperative baseline MAP through the first 24h after cardiac surgery and the specified non-renal adverse outcomes. These aims will be achieved by regression modelling of longitudinal MAP profiles created from minute-by-minute MAP data through 24h postoperatively in patients undergoing cardiac surgery. Combined with validated outcome data and adjusted for key potentially confounding covariates appropriate to each outcome, we will test the hypothesis that: Increased time spent with MAP in each of the multiple discrete range-bands through 24h after surgery (relative to a reference MAP range-band) is associated with an increased odds for AKI and, separately, other non-renal outcomes. Our results will provide critical evidence to guide the data-driven selection of the most appropriate target MAP for a future trial testing the effectiveness of this alternate target MAP to reduce AKI and improve patient outcome after cardiac surgery.