Costanzo Maria Rosa, Agostoni Piergiuseppe, Marenzi Giancarlo
Contrib Nephrol. 2010;164:173-198. doi: 10.1159/000313730. Epub 2010 Apr 20.
More than one million hospitalizations occur annually in the US because of heart failure (HF) decompensation caused by fluid overload. Congestion contributes to HF progression and mortality. Apart from intrinsic renal insufficiency, venous congestion, rather than a reduced cardiac output, may be the primary hemodynamic factor driving worsening renal function in patients with acutely decompensated HF. According to data from large national registries, approximately 40% of hospitalized HF patients are discharged with unresolved congestion, which may contribute to unacceptably high rehospitalization rates. Although diuretics reduce the symptoms and signs of fluid overload, their effectiveness is reduced by excess salt intake, underlying chronic kidney disease, renal adaptation to their action and neurohormonal activation. In addition, the production of hypotonic urine limits the effectiveness of loop diuretics in reducing total body sodium. Ultrafiltration is the mechanical removal of fluid from the vasculature. Hydrostatic pressure is applied to blood across a semipermeable membrane to separate isotonic plasma water from blood. Because solutes in blood freely cross the semipermeable membrane, large amounts of fluid can be removed at the discretion of the treating physician without affecting any change in the serum concentration of electrolytes and other solutes. Ultrafiltration has been used to relieve congestion in patients with HF for almost four decades. In contrast to the adverse physiological consequences of loop diuretics, numerous studies have demonstrated favorable responses to ultrafiltration. Such studies have shown that removal of large amounts of isotonic fluid relieves symptoms of congestion, improves exercise capacity, improves cardiac filling pressures, restores diuretic responsiveness in patients with diuretic resistance, and has a favorable effect on pulmonary function, ventilatory efficiency, and neurohormonal activation. Ultrafiltration is the only fluid removal strategy shown to improve outcomes in randomized controlled trials of patients hospitalized with decompensated HF.
在美国，每年因液体超负荷导致的心衰（HF）失代偿而住院的人数超过100万。充血会促进HF的进展并导致死亡。除了内在的肾功能不全外，静脉充血而非心输出量减少，可能是急性失代偿性HF患者肾功能恶化的主要血流动力学因素。根据大型国家登记处的数据，约40%的住院HF患者出院时充血问题仍未解决，这可能导致高得令人难以接受的再住院率。尽管利尿剂可减轻液体超负荷的症状和体征，但过量盐摄入、潜在的慢性肾病、肾脏对其作用的适应性以及神经激素激活会降低其疗效。此外，低渗尿的产生限制了袢利尿剂在减少总体钠方面的有效性。超滤是从血管系统中机械性去除液体。通过半透膜对血液施加静水压，以将等渗血浆水与血液分离。由于血液中的溶质可自由穿过半透膜，治疗医生可根据需要去除大量液体，而不会影响血清电解质和其他溶质浓度的任何变化。超滤已用于缓解HF患者的充血症状近四十年。与袢利尿剂的不良生理后果相反，大量研究已证明超滤会产生良好反应。此类研究表明，去除大量等渗液可缓解充血症状、提高运动能力、改善心脏充盈压、恢复利尿剂抵抗患者的利尿剂反应性，并对肺功能、通气效率和神经激素激活产生有利影响。在失代偿性HF住院患者的随机对照试验中，超滤是唯一被证明可改善预后的液体去除策略。
