Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
J Appl Physiol (1985). 2020 Mar 1;128(3):667-680. doi: 10.1152/japplphysiol.00705.2019. Epub 2020 Feb 13.
High portal venous blood flow (Qpv) may contribute to posthepatectomy liver failure. Both Trendelenburg position (TP) and elevated airway pressure (Paw) increase backpressure to venous return and may thereby reduce Qpv. The aim of this study was to evaluate the effects of TP and increased Paw on hepatosplanchnic hemodynamics before and after major liver resection. Arterial and venous blood pressures, Qpv, extrasplanchnic inferior vena cava (Qivc), superior mesenteric (Qsma), hepatic (Qha), and carotid artery blood flows (Qca) were measured in 14 anesthetized and mechanically ventilated pigs in supine and 30° TP during end-expiratory hold at 5 cmHO positive end-expiratory pressure (PEEP) and during inspiratory hold with Paw of 15, 20, 25, and 30 cmHO. After major liver resection, the interventions were repeated in seven randomly selected animals. At baseline, TP increased right atrial pressure (Pra) and Qpv but not Qivc or Qsma. With increased Paw in the supine position, Pra increased and all regional blood flows decreased. TP during increasing Paw attenuated the decrease in Qpv, Qsma, and Qivc but not in Qha or Qca. After liver resection, the effects of TP during increasing Paw remained, albeit at higher portal vein pressures. However, TP alone did not increase IVC venous return. Increasing Paw in supine position reduces Qpv and all other regional flows, while the reduction in Qpv is attenuated in TP, suggesting partly preserved liver waterfall or decreased intrahepatic resistance. Liver resection, despite resulting in major intrahepatic blood flow changes, does not fundamentally influence the interaction of increasing Paw and TP on regional perfusion. In Trendelenburg position (TP), liver blood flow is the only contributor to increased venous return measured in the inferior vena cava (IVC), which attenuates the decreased IVC venous return induced by increasing airway pressure. After liver resection, TP similarly attenuated effects of increasing airway pressure.
高门静脉血流（Qpv）可能导致肝切除术后肝功能衰竭。Trendelenburg 体位（TP）和升高的气道压力（Paw）都会增加静脉回流的后负荷，从而可能减少 Qpv。本研究旨在评估 TP 和升高的 Paw 在肝切除术前和术后对肝脾血流动力学的影响。在仰卧位和 30°TP 下，对 14 只麻醉和机械通气的猪进行动脉和静脉血压、Qpv、腔外下腔静脉（Qivc）、肠系膜上动脉（Qsma）、肝（Qha）和颈总动脉血流（Qca）的测量。在呼气末保持 5cmH2O 呼气末正压通气（PEEP）和吸气末保持 Paw 为 15、20、25 和 30cmH2O 时。在主要肝切除术后，对 7 只随机选择的动物重复进行干预。在基线时，TP 增加了右心房压（Pra）和 Qpv，但不增加 Qivc 或 Qsma。在仰卧位时，随着 Paw 的增加，Pra 增加，所有区域血流量减少。TP 在增加 Paw 时减轻了 Qpv、Qsma 和 Qivc 的减少，但不能减轻 Qha 或 Qca 的减少。肝切除术后，增加 Paw 时的 TP 作用仍然存在，尽管门静脉压力较高。然而，单独的 TP 并不能增加 IVC 的静脉回流。在仰卧位时增加 Paw 会降低 Qpv 和所有其他区域的血流量，而在 TP 时 Qpv 的降低幅度会减轻，这表明部分保留了肝瀑布或降低了肝内阻力。尽管肝切除术后肝内血流发生了重大变化，但并未从根本上影响增加 Paw 和 TP 对区域灌注的相互作用。在 Trendelenburg 体位（TP）中，肝脏血流是测量腔静脉（IVC）中增加静脉回流的唯一贡献者，这减轻了气道压力增加引起的 IVC 静脉回流减少。肝切除术后，TP 同样减轻了气道压力增加的影响。
