Franz M, Pohanka E, Tribl B, Woloszczuk W, Hörl W H
Department of Internal Medicine, University of Vienna, Austria.
Kidney Int Suppl. 1997 Jun;59:S39-42.
The hydration state of a hemodialysis patient reflects the balance between fluid overload, normovolemia and underhydration. Since chronic volume overload enhances the cardiac mortality, and chronic underhydration carries the risk for dialysis-associated hypotension, treatment for the deranged water homeostasis of hemodialysis patients needs to focus on an accurate assessment of dry body weight. Non-invasive methods such as echocardiography of the inferior caval vein diameter (ICVD) or conductivity measurements are considered as reliable techniques to estimate the hydration state of hemodialysis patients. The value of biochemical parameters for an adequate assessment of dry body weight remains controversial. In our study we have determined cyclic guanosine 3'5'-monophosphate (cGMP) serum levels in 125 patients undergoing regular hemodialysis. Predialytic cGMP significantly decreased from 46.1 +/- 26.0 to 17.0 +/- 9.3 pmol/liter post-dialysis (P < 0.001). In 35 patients cGMP level after hemodialysis remained > 20 pmol/liter, but non of these patients displayed any clinical signs of fluid overload. In a group of patients with normal heart function (N = 29) additional sonography of the ICVD revealed normovolemia in 16 patients, underhydration in 5 patients and fluid overload in 4 patients. The respective post-dialytic mean cGMP level was significantly higher in the overhydrated group compared to normovolemic and underhydrated patients (25.3 +/- 10.8 vs. 14.7 +/- 6.4 and 11.4 +/- 5.3 pmol/liter, P < 0.02). However, there was no significant correlation between cGMP level and ICVD (r = 0.5, NS). We conclude that there is no single parameter to define the adequate dry body weight of a hemodialysis patient. Our own data demonstrate the limitations using cGMP, particularly in estimating underhydration. ICVD and bioimpedance offer non-invasive methods for both volume overload and underhydration, and seem to be reliable in the routine assessment of dry body weight.
血液透析患者的水合状态反映了液体超负荷、血容量正常和水合不足之间的平衡。由于慢性容量超负荷会增加心脏死亡率，而慢性水合不足会带来透析相关性低血压的风险，因此血液透析患者紊乱的水平衡治疗需要侧重于准确评估干体重。诸如下腔静脉直径（ICVD）的超声心动图或电导率测量等非侵入性方法被认为是评估血液透析患者水合状态的可靠技术。生化参数对干体重进行充分评估的价值仍存在争议。在我们的研究中，我们测定了125例接受定期血液透析患者的环磷酸鸟苷（cGMP）血清水平。透析前cGMP从46.1±26.0显著降至透析后17.0±9.3 pmol/升（P<0.001）。在35例患者中，血液透析后cGMP水平仍>20 pmol/升，但这些患者均未表现出任何液体超负荷的临床体征。在一组心功能正常的患者（N=29）中，对ICVD进行额外的超声检查发现，16例患者血容量正常，5例患者水合不足，4例患者液体超负荷。与血容量正常和水合不足的患者相比，液体超负荷组透析后的平均cGMP水平显著更高（25.3±10.8 vs.14.7±6.4和11.4±5.3 pmol/升，P<0.02）。然而，cGMP水平与ICVD之间无显著相关性（r=0.5，无显著性差异）。我们得出结论，没有单一参数可以定义血液透析患者的合适干体重。我们自己的数据证明了使用cGMP的局限性，尤其是在估计水合不足方面。ICVD和生物电阻抗为液体超负荷和水合不足提供了非侵入性方法，并且在干体重的常规评估中似乎是可靠的。
