Method for Approximating Colloid Osmotic Pressure in Long‐Term Hemodialysis Patients

Abstract

Colloid osmotic pressure (COP) is important in calculating vascular permeability during hemodialysis (HD). However, few reports have directly measured COP in HD patients. Therefore, the currently published formulas may not be clinically optimal for predicting COP for HD patients. Here, the study aims were (i) to directly measure COP in HD patients and compare the measured and predicted COP values using four previously reported formulas, and (ii) to develop a formula for approximating COP using clinical parameters. We obtained 212 measured COP values using an osmometer; the average value was 22.0 ± 0.2 mm Hg. The predicted COP based on the four different formulas was positively correlated with the measured COP (0.87 < r < 0.89), but was significantly overestimated compared to it (P < 0.001). We also performed a stepwise analysis using serum albumin and non-albumin protein concentrations and obtained the following simple formula for COP approximation: COP (mm Hg) = -7.91 + 5.64 × albumin (g/dL) + 3.00 × non-albumin proteins (g/dL). A positive linear correlation was observed between the measured COP and approximated COP using this formula (r = 0.90, P < 0.001). We calculated the mean Kr (plasma-refilling coefficient) as a marker for determining dry weight in HD patients using the measured COP and approximated COP. No differences were observed between the mean Kr derived from the measured and approximated COP. We report here significant differences between measured and predicted COP values, and have devised a simple formula for COP approximation in HD patients.

Effects of dietary intake and nutritional status on cerebral oxygenation in patients with chronic kidney disease not undergoing dialysis: A cross-sectional study

“…Regarding the association between cerebral rSO 2 and nutritional parameters in this study, serum albumin concentration and Hb level were significantly associated with cerebral rSO 2 in multivariate linear regression analysis. Serum albumin concentration, the main determinant of colloid osmotic pressure in vessels, plays an important role in maintaining microcirculation in systemic tissues via the movement of body fluids, mainly between the vessels and interstitium [43]. Furthermore, consistent with the present study, serum albumin concentration has been reported to be significantly associated with cerebral oxygenation in patients with all stages of CKD, as well as patients undergoing HD [15,17].…”

Association of cerebral oxygenation with estimated glomerular filtration rate and cognitive function in chronic kidney disease patients without dialysis therapy

“…Serum albumin concentration, the main determinant of colloid osmotic pressure in vessels, plays an important role in the regulation of fluid exchange across the microvascular wall. Therefore, albumin itself plays an essential role in maintaining microcirculation in systemic tissues via the body- fluid movement, mainly between the vessels and interstitium [ 29 ]. To date, serum albumin concentration has reportedly been associated with CKD progression [ 30 ], prognosis in CKD patients [ 31 ], and trajectory of cognitive function in community-dwelling adults [ 32 ].…”

Changes in Cerebral Oxygenation Associated with Intradialytic Blood Transfusion in Patients with Severe Anemia Undergoing Hemodialysis

“…In addition to the cerebral oxygen supply decrease induced by severe anemia, the significant decrease in serum albumin concentration in HD patients with severe anemia might be associated with the cerebral rSO 2 reduction in this study. Colloid osmotic pressure is one of the important factors maintaining a systemic microcirculation (including that in the brain), and serum albumin concentration mainly constitutes the formation of colloid osmotic pressure [19]. In HD patients with well-maintained Hb levels, cerebral rSO 2 was independently and positively associated with serum albumin concentration [6].…”