Shi Zhen-wei, Wang Zhi-gang
Department of Nephrology, Friendship Hospital of Capital Medical University, Beijing, China.
Chin Med J (Engl). 2008 Jun 5;121(11):1003-9.
The dialysis disequilibrium syndrome is characterized by neurologic deterioration and cerebral edema which occurs after hemodialysis. The purpose of this study was to investigate the pathogenesis of acute cerebral and pulmonary edema induced by hemodialysis.
We evaluated the effects of hemodialysis on the biochemical and hemodynamic parameters of the plasma and cerebrospinal fluid, including the intracranial pressure, dry/wet ratio, and pulmonary edema index, and we also examined the pathological changes of the brain and lung tissue in dogs suffering from uremia.
Seventy-two hours after bilateral ureteral ligation, 10 uremic dogs were hemodialyzed for 2 hours, yielding a 73.6% and 60.1% decrease in the plasma urea and creatinine, respectively, a decrease in the plasma osmolality from (359 +/- 18) mOsm/kg H(2)O to (304 +/- 6) mOsm/kg H(2)O (P < 0.01), a decrease in the dry/wet ratio of the lung and brain tissue, and an increase in the hemodynamic parameters (right atrial pressure, right ventricular pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, and central venous pressure), intracranial pressure, total pulmonary resistance index, and pulmonary edema index. Moreover, the pathological examination revealed lung and brain edema in the dialyzed dogs. This group was compared to 3 control groups: 6 uremic dogs which were sham dialyzed without dialysate so that no fall in the plasma urea occurred, and 12 uremic and 12 nonuremic animals that were not dialyzed. However, the parameters mentioned above were not significantly changed among these 3 control groups.
The acute brain and lung edema in our model appeared to be primarily due to a large osmotic gradient between the plasma and the brain and lung. This is the "urea reverse effect" which promoted the osmotically-induced lung and brain swelling.
透析失衡综合征的特征是血液透析后出现神经功能恶化和脑水肿。本研究的目的是探讨血液透析引起急性脑和肺水肿的发病机制。
我们评估了血液透析对血浆和脑脊液生化及血流动力学参数的影响，包括颅内压、干湿比和肺水肿指数，还检查了尿毒症犬脑和肺组织的病理变化。
双侧输尿管结扎72小时后，对10只尿毒症犬进行2小时的血液透析，血浆尿素和肌酐分别下降73.6%和60.1%，血浆渗透压从(359±18)mOsm/kg H₂O降至(304±6)mOsm/kg H₂O(P<0.01)，肺和脑组织的干湿比降低，血流动力学参数（右心房压、右心室压、肺动脉压、肺毛细血管楔压和中心静脉压）、颅内压、总肺阻力指数和肺水肿指数升高。此外，病理检查显示透析犬出现脑和肺水肿。将该组与3个对照组进行比较：6只尿毒症犬进行假透析，不使用透析液，因此血浆尿素未下降；12只尿毒症动物和12只非尿毒症动物未进行透析。然而，这3个对照组中上述参数无明显变化。
我们模型中的急性脑和肺水肿似乎主要是由于血浆与脑和肺之间存在较大渗透梯度。这就是“尿素反向效应”，它促进了渗透压引起的脑和肺肿胀。
