猪出血性休克模型中的无创和侵入性肾缺氧监测
Summary
本文介绍的是在出血性休克猪模型中测量髓质中的肾氧合和无创尿氧分压的方案，以确定尿氧分压作为急性肾损伤 （AKI） 的早期指标和新的复苏终点。
Abstract
高达 50% 的创伤患者会出现急性肾损伤 （AKI），部分原因是严重失血后肾灌注不良。目前，AKI 的诊断依据是血清肌酐浓度较基线的变化或尿量长时间减少。不幸的是，大多数创伤患者的基线血清肌酐浓度数据不可用，目前的估计方法也不准确。此外，血清肌酐浓度可能直到受伤后24-48小时才会改变。最后，少尿必须持续至少6小时才能诊断AKI，这使得早期诊断不切实际。目前可用的AKI诊断方法对于预测创伤患者复苏期间的风险没有用。研究表明，尿氧分压 （PuO2） 可能有助于评估肾缺氧。开发了一种连接导尿管和尿液收集袋的监测器，用于无创测量 PuO2。该设备集成了一个光学氧传感器，可根据发光猝灭原理估计PuO2。此外，该设备测量尿流量和温度，后者用于调节温度变化的混杂效应。测量尿流量以补偿低尿流量期间氧气进入的影响。本文介绍了一种猪失血性休克模型，以研究无创PuO2、肾缺氧与AKI发生之间的关系。该模型的一个关键要素是超声引导的手术放置在氧探头的肾髓质中，该探头基于未出鞘的微光纤。PuO 2 也将在膀胱中测量，并与肾脏和非侵入性 PuO2 测量进行比较。该模型可用于测试 PuO 2 作为 AKI 的早期标志物，并将 PuO2 评估为出血后的复苏终点，提示终末器官而不是全身氧合。
Introduction
急性肾损伤 （AKI） 影响高达 50% 的重症监护病房收治的创伤患者1.发生 AKI 的患者往往住院和重症监护病房的住院时间更长，死亡风险高 3,3,4。目前，AKI 最常由肾脏疾病改善全球结局 （KDIGO） 指南定义，该指南基于血清肌酐浓度从基线或长期少尿期间的变化5。大多数创伤患者的基线肌酐浓度数据不可用，估计方程不可靠，尚未在创伤患者中得到验证6。此外，血清肌酐浓度可能直到受伤后至少24小时才会改变，从而排除了早期识别和干预7。虽然研究表明尿量是 AKI 的早期指标，而不是血清肌酐浓度，但 KDIGO 标准要求至少 6 小时的少尿，这排除了针对伤害预防的干预措施8.定义AKI的最佳每小时尿量阈值和适当的少尿持续时间也存在争议，这限制了其作为疾病早期标志物的有效性9,10。因此，目前针对 AKI 的诊断措施在创伤环境中没有用处，导致 AKI 诊断延迟，并且不能提供有关患者发生 AKI 的风险状态的实时信息。
虽然创伤环境中 AKI 的发生很复杂，并且可能与多种原因有关，例如低血容量导致的肾灌注不良、血管收缩导致的肾血流量减少、创伤相关炎症或缺血再灌注损伤，但肾缺氧是大多数 AKI11,12 的常见因素。特别是，肾脏的髓质区域极易受到创伤环境中氧气需求和供应之间的不平衡的影响，这是由于氧气输送减少和与钠重吸收相关的高代谢活动。因此，如果可以测量肾髓质氧合，则可以监测患者发生AKI的风险状态。虽然这在临床上不可行，但肾脏出口处的尿氧分压 （PuO2） 与髓质组织氧合密切相关13,14。其他研究表明，可以测量膀胱 PuO 2，并且它会响应改变髓质氧和肾盂 PuO2 水平的刺激而变化，例如肾血流量减少15,16,17。这些研究表明，PuO2 可能提示终末器官灌注，并可能有助于监测创伤环境中干预对肾功能的影响。
为了无创监测 PuO 2，开发了一种无创 PuO2 监测仪，该监测仪可以轻松连接到体外导尿管的末端。非侵入式 PuO2 监测仪由三个主要组件组成：温度传感器、发光淬灭氧传感器和基于热的流量传感器。由于每个氧传感器都是基于光学的，并且依赖于Stern-Volmer关系来量化发光和氧浓度之间的关系，因此需要温度传感器来抵消温度变化的任何潜在混杂效应。流量传感器对于量化尿量和确定尿流的方向和大小非常重要。所有三个组件均通过公、母和 T 形鲁尔锁连接器和聚氯乙烯 （PVC） 柔性管的组合连接。带有锥形连接器的一端连接到导尿管的出口，锥形连接器上带有管道的末端连接尿液收集袋连接器上的滑块。
尽管测量距离膀胱远端，但最近的一项研究表明，心脏手术期间尿 PuO2 偏低与发生 AKI18,19 的风险增加有关。同样，目前的动物模型主要集中在心脏手术和败血症期间AKI的早期检测14,20,21,22。因此，关于在创伤环境中使用这种新型设备仍然存在问题。本研究的目的是确定PuO2作为AKI的早期标志物，并研究其作为创伤患者的复苏终点的用途。本手稿描述了出血性休克的猪模型，其中包括在肾髓质中放置无创 PuO 2 监测仪、膀胱 PuO2 传感器和组织氧传感器。来自无创监测仪的数据将与膀胱 PuO2 和侵入性组织氧测量进行比较。无创监护仪还包括一个流量传感器，该传感器将有助于了解尿流速和进氧之间的关系，这降低了尿液穿过尿路时从无创 PuO2 推断肾髓质组织氧合的能力。此外，来自三个氧传感器的数据将与全身生命体征（如平均动脉压）进行比较。核心假设是无创 PuO2 数据与侵入性髓质氧含量密切相关，并将反映复苏期间的髓质缺氧。无创 PuO2 监测有可能通过更早地识别 AKI 并作为出血后提示终末器官而非全身氧合的新型复苏终点来改善创伤相关结局。
Protocol
Representative Results
Discussion
AKI 是创伤患者的常见并发症，目前，没有经过验证的肾组织肺氧合床旁监测仪，可以更早地发现 AKI 并指导潜在的干预措施。本手稿描述了猪出血性休克模型的使用和仪器，以建立无创 PuO2 作为 AKI 的早期指标和创伤环境中的新型复苏终点。
这种猪模型的一个明显优势是能够比较三个不同位置的氧气测量值，包括直接在髓质中。虽然可以测量人体的膀胱和非侵入性PuO<…
Disclosures
The authors have nothing to disclose.
Acknowledgements
该赠款的工作由犹他大学临床和转化科学研究所通过转化和临床研究试点计划和国防部国会指导医学研究计划办公室（PR192745）资助。
Materials
| 1/8" PVC tubing | Qosina | SKU: T4307 | Part of noninvasive PuO2 monitor |
| 3/16" PVC tubing | Qosina | SKU: T4310 | Part of noninvasive PuO2 monitor |
| 3/8" TPE tubing | Qosina | SKU: T2204 | Part of noninvasive PuO2 monitor |
| 3/32" (1), 1/8" (1), 5/32" (1) drill bit | Dewalt | N/A | For building noninvasive PuO2 monitor |
| Biocompatible Glue | Masterbond | EP30MED | Part of noninvasive PuO2 monitor |
| Bladder PuO2 sensor | Presens | DP-PSt3 | Oxygen dipping probe |
| Bladder oxygen measurement device | Presens | Fibox 4 | Stand-alone fiber optic oxygen meter |
| Chlorhexidine 4% scrub | Vetone | N/A | For scrubbing insertion or puncture sites |
| Conical connector with female luer lock | Qosina | SKU: 51500 | Part of noninvasive PuO2 monitor |
| Cuffed endotracheal tube | Vetone | 600508 | For sedating the subject and providing respiratory support |
| Euthanasia solution (pentobarbital sodium|pheyntoin sodium) | Vetone | 11168 | For euthanasia after completion of experiment |
| General purpose temperature probe, 400 series thermistor | Novamed | 10-1610-040 | Part of noninvasive PuO2 monitor |
| HotDog veterinary warming system | HotDog | V106 | For controlling subject temperature during experiment |
| Invasive tissue oxygen measurement device | Optronix | N/A | OxyLite™ oxygen monitors |
| Invasive tissue oxygen sensor | Optronix | NX-BF/OT/E | Oxygen/Temperature bare-fibre sensor |
| Isoflurane | Vetone | 501017 | To maintain sedation throughout the experiment |
| Isotonic crystalloid solution | HenrySchein | 1537930 or 1534612 | Used during resuscitation in the critical care period |
| Liquid flow sensor | Sensirion | LD20-2600B | Part of noninvasive PuO2 monitor |
| Male luer lock to barb connector | Qosina | SKU: 11549 | Part of noninvasive PuO2 monitor |
| Male to male luer connector | Qosina | SKU: 20024 | Part of noninvasive PuO2 monitor |
| Norepinephrine | HenrySchein | AIN00610 | Infusion during resuscitation |
| Noninvasive oxygen measurement device | Presens | EOM-O2-mini | Electro optical module transmitter for contactless oxygen measurements |
| Non-vented male luer lock cap | Qosina | SKU: 65418 | Part of noninvasive PuO2 monitor |
| O2 sensor stick | Presens | SST-PSt3-YOP | Part of noninvasive PuO2 monitor |
| PowerLab data acquisition platform | AD Instruments | N/A | For data collection |
| REBOA catheter | Certus Critical Care | N/A | Used in experimental protocol |
| Super Sheath arterial catheters (5 Fr, 7 Fr, 9 Fr) | Boston Scientific | C1894 | for intravascular access |
| Suture | Ethicon | C013D | For securing catheter to skin and closing incisions |
| T connector, all female luer locks | Qosina | SKU: 88214 | Part of noninvasive PuO2 monitor |
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