Kinetics of acid-base parameters in conventional hemodialysis

Details about the acid-base changes in hemodialysis are scarce in the literature but are potentially relevant to adequate management of patients. We addressed the acid-base kinetics during hemodialysis and throughout the interdialytic period in a cross-sectional study of adults undergoing conventional hemodialysis. Samples for blood gas analysis were obtained from the arterial limb of the arteriovenous fistula before the first session of the week (HD1), immediately at the end of HD1, and on sequential collections at 15, 30, 45, 60, and 120 min post-HD1. Additional blood samples were collected after ∼20 h following the end of the first dialysis and immediately prior to the initiation of the second dialysis of the week. Thirty adult patients were analyzed (55±15 years, 50% men, 23% diabetic; dialysis vintage 69±53 months). Mean serum bicarbonate levels increased at the end of HD1 (22.3±2.7 mEq/L vs 17.5±2.3 mEq/L, P<0.001) and remained stable until 20 h after the end of the session. The mean values of pCO2 before HD1 were below reference and at 60 and 120 min post-HD1 were significantly lower than at the start (31.3±2.7 mmHg and 30.9±3.7 mmHg vs 34.3±4.1 mmHg, P=0.041 and P=0.010, respectively). The only point of collection in which mean values of pCO2 were above 35 mmHg was 20 h post-dialysis. Serum bicarbonate levels remained stable for at least 20 h after the dialysis sessions, a finding that may have therapeutic implications. During dialysis, the respiratory response for correction of metabolic acidosis (i.e., pCO2 elevation) was impaired.

Effect of body composition on dialysis quality(Kt/V): a single center study / 中华肾脏病杂志

Objective To investigate the relationship between body composition and adequacy of dialysis,and analyze the related risk factors for inadequate delivery of hemodialysis.Methods In a prospective clinical trial,two different methods determining dialysis dose were simultaneously applied:Kt/Vdau (conventional method with Daugirdas' formula) and Kt/Vbem [online clearance monitoring (OCM) measurement with Ⅴ measured by body composition monitor (BCM)].Using the value of 1.27 as the boundary,the patients were divided into two groups:Kt/Vbcm ＜ 1.27 group and Kt/Vbcm≥ 1.27 group.Clinical indices were compared between the two groups.Multiple linear regression was applied to analyze the potential impact factors of the difference between Kt/V values calculated by the two methods.Receiver operator characteristic (ROC) curve was applied to analyze meaningful factors.Results A total of 138 maintenance hemodialysis patients with age of (54.9±12.7) years old were enrolled,and 55.1％ of them were males.There was no significant difference between Kt/Vdau and Kt/Vbcm [1.432(1.235,1.718) vs 1.434 (1.244,1.642),P=0.823].Kt/Vdau was incidentally prone to falsely high values due to operative errors,whereas in these cases OCM-based measurement Kt/Vbcm delivered realistic values.An excellent correlation was observed between Kt/Vdau and Kt/Vbcm;the mean difference was 0.07,95％CI (-0.66-0.79);the correlation coefficient was 0.842(0.821-0.862).The patients in Kt/Vbcm≥ 1.27 group had older age,lower body mass index (BMI),lower height and weight,lower total body water (TBW),lower extracellular water,lower intracellular water,and lower lean tissue index (LTI) compared to those in Kt/Vbcm ＜ 1.27 group.Excellent correlations were observed between Kt/Vbcm and TBW or LTI (r=-0.834,P ＜ 0.001;r=-0.721,P ＜ 0.001).ROC curve analysis showed that the sensitivity and specificity of predicting inadequate delivery of hemodialysis were 87.1％ and 86.5％,with a threshold of 30 L for TBW.It also showed that the sensitivity and specificity of predicting inadequate delivery of hemodialysis were 60.4％ and 94.6％,with a threshold of 11.05 kg/m2 for LTI.Conclusions BCM can give more accurate parameters of urea distribution volume,thus modifying the result of Kt/V.TBW and LTI are important risk influencing factors for inadequately dialysis,and special attention should be paid to patients with TBW ＞ 30 L or LTI ＞ 11.05 kg/m2.

Clinical Significances of Carbamylated Hemoglobin in Patients with Chronic Renal Failure / 대한신장학회잡지

Carbamylated hemoglobin (CarHb) is formed by the reaction of hemoglobin with cyanate derived from the spontaneous dissociation of in vivo urea. Previous studies have shown that formation of CarHb depends upon both the severity and the duration of renal failure. To study the clinical significances of CarHb in Korean patients with chronic renal failure, we measured CarHb levels by high-performance liquid chromatography in 159 CRF patients and 46 normal controls. Patients with CRF had a higher CarHb concentration than normal controls (107.9+/-58.8 vs 35.1+/-14.2 microgramVH/gHb; P<0.001). In patients with CRF, nondialysis group had a higher value than dialysis group (129.8+/-77.9 vs 98.7+/-46.1 microgramVH/gHb; P<0.05). There were no siginificant difference in CarHb levels between hemodialysis (92.0+/-35.8microgramVH/gHb) and peritoneal dialysis (106.7+/-55.3microgramVH/gHb) groups. CarHb levels were not different between diabetic and nondiabetic patients in predialysis and hemodialysis groups. Although there was a significant difference in peritoneal dialysis group, the BUN levels were also lower in diabetic patients than nondiabetic patients. There were no correlation between CarHb and HbA1c percentage in patients with diabetes. CarHb levels were positively correlated with BUN (r=0.489; P<0.001) and creatinine (r=0.458; P<0.01) concentrations. There were negative correlations between CarHb and both Kt/V (r=-0.358; P<0.05) and URR (r=-0.415; P<0.05) in hemodialysis patients. In conclusion, CarHb may be a useful index of uremic control in patients with chronic renal failure, and are independent of the mode of dialysis and the presence of diabetes.