Brain density changes during renal replacement in critically ill patients with acute renal failure. Continuous hemofiltration versus intermittent hemodialysis.

Computerized tomography (CT) studies of the brain were made on 12 patients with acute renal failure from different origin. Patients were treated for two subsequent days in random sequence with intermittent hemodialysis (HD) (one 4-h session and Kt/V > or = 1) and continuous veno-venous hemofiltration (CVVH) (one 24-h session and Kt/V > or = 1). CT scans were done before and after the HD and CVVH session in each patient. In baseline conditions, the only macroscopic morphological alteration was a slight brain edema in some patients. Significant changes in the density of white and gray matter were observed after the HD session in all patients (gray matter from 52.3 +/- 5.2 to 38.9 +/- 5.3 and white matter from 36.7 +/- 3.5 to 24.8 +/- 3.2 Hounsfield units, average delta -26.7%). No changes were observed after CVVH. We conclude that intermittent HD involves a remarkable degree of "unphysiology", leading to increased water content in the brain after each session. In acute patients this may lead to a post-dialytic brain edematogenic state. The physiological stability provided by continuous therapies such as CVVH avoids this unwanted effect, and suggests that continuous renal replacement therapies should be a first choice in these patients.     

Continuous hemofiltration vs hemodialysis for the acute renal failure after cardiovascular surgery

Recently we have performed continuous hemofiltration (CHF) for the patients of acute renal failure after cardiovascular surgery. In this article, we discuss the effectiveness of CHF in the acute phase of renal failure after cardiovascular surgery compared with hemodialysis (HD). CHF group included 12 cases, and HD group included 19 cases. Two cases (16.7%) of CHF group and two cases (10.5%) of HD group were survived and discharged from hospital. Filtration volume of CHF (93.8 +/- 81.0 l) was significantly higher than that of HD (27.1 +/- 22.9 l), but filtration rate of CHF (410 +/- 87.4 ml/H) was significantly lower than that of HD (572 +/- 167 ml/H). Thus CHF removed excess water more gently and effectively than HD. Because the influence to the hemodynamics of CHF was much less than that of HD, we were able to start CHF (4.3 +/- 4.6 days after operation, BUN: 55.3 +/- 19.5 mg/dl), Cr: 3.95 +/- 0.63 mg/dl) significantly earlier than HD (7.8 +/- 4.1 days after operation, BUN: 113.1 +/- 29.4 mg/dl, Cr: 6.10 +/- 1.04 mg/dl). We needed high dose catecholamine or blood transfusion for the 11 cases (57.3%) of HD group during HD, but we needed them for only 1 case (8.3%) of CHF group. We concluded that CHF was safer and more useful than HD in the treatment of acute renal failure after cardiovascular surgery.     

Outcomes of acute renal failure patients requiring intermittent hemodialysis

The published studies on the prognosis of patients requiring intermittent hemodialysis (IHD) are scarce and have some conflicts. In this study, we retrospectively analyzed our data on ARF patients who were treated with IHD. A total of 192 (female: 85, 44.3%; male: 107, 55.7%) patients were included in the study. The mean age was 56.3 +/- 17.1 years. In all, 48.9% of the patients were older than 60 years. The mean number of IHD sessions was 7.8 +/- 8.0 per patient; 12.4% was due to prerenal causes, 76.8% was due to intrarenal causes, and 10.8% was due to postrenal causes. The leading indication of the IHD was uremic symptoms (46.8%). With the exclusion of hypertension, 72.4% of the patients had at least one systemic comorbidity. After treatment, 75.5% of the patients recovered, in contrast to 9.4% of patients who were transferred to chronic renal replacement programs and 15.1% who died during IHD period. Pre-dialytic serum creatinine (p = 0.003) and albumin levels (p = 0.016), total IHD session number per patient (p = 0.003), and age (p = 0.034) were the parameters that were related to high mortality in statistical analysis. Mortality was higher if the leading indication of IHD was biochemical disturbances (p = 0.013). Diabetes mellitus did not influence mortality. Consequently, predialytic serum creatinine and albumin levels may be very important predictors of mortality. Patients in high-risk groups (older age, female sex, and low pre-dialytic creatinine and albumin levels) should be considered to be treated with slow continuous renal replacement methods.     

Continuous venovenous hemodiafiltration versus hemodialysis as renal replacement therapy in patients with acute renal failure in the intensive care unit

OBJECTIVE: Hemodialysis (HD) and continuous venovenous hemodiafiltration (CVVHDF) have been adopted as forms of renal replacement therapy (RRT) in patients with acute renal failure (ARF). Although CVVHDF has many advantages, previous studies reported no definite improvement in survival rate compared to HD. MATERIAL AND METHODS: In this retrospective study, 148 intensive care unit patients underwent HD (70 males, 25 females; mean age 45 +/- 17 years) or CVVHDF (42 males, 11 females; mean age 52 +/- 18 years). The severity of illness was estimated at the initiation of RRT and on the third day of RRT and presented using the APACHE III scoring system. The number of organ failures was checked at the initiation of RRT. RESULTS: The survival rate was 46% in the HD group and 21% in the CVVHDF group (p = 0.002). CVVHDF was applied to the more severely ill patients, who had longer periods using a ventilator (p = 0.002) and/or vasopressor (p < 0.001), higher numbers of organ failures (p < 0.001) and higher initial APACHE III scores (p < 0.001). Among patients with APACHE III scores > 103, the survival rate was 13% in the CVVHDF group and 0% in the HD group. In patients with kidney failure and failure of two other organs, the survival rate was 9% in the HD group and 36% in the CVVHDF group (p = 0.035). CONCLUSION: The mortality rate in the CVVHDF group was higher than that in the HD group, which may have been because CVVHDF was applied to the more severely ill patients. In contrast, CVVHDF may give a chance of survival to patients with APACHE III scores > 103 and may be more useful than HD in patients with failure of three or more organs.     

Blood volume monitoring in intermittent hemodialysis for acute renal failure

BACKGROUND: Although hypotension commonly accompanies intermittent hemodialysis for acute renal failure (ARF) in the intensive care unit (ICU), little is known about how it may be prevented. Online relative blood volume (RBV) monitoring has been used to reduce hypotension in chronic hemodialysis, but is of unproven benefit in ARF. This study tested the hypothesis that hypotension is predictable using online RBV monitoring in patients dialyzed for ARF in an ICU setting. METHODS: The primary definition of hypotension was mean arterial pressure (MAP) <70 mm Hg; systolic blood pressure (SBP) <100 mm Hg was used as a secondary outcome. Fifty-seven treatments were prospectively studied in twenty consecutive adult patients treated with intermittent hemodialysis. RBV was continuously measured using the Hemoscan device (Gambro). RESULTS: Hypotension occurred in 30% of treatments as defined by MAP, and 18% as defined by SBP. There was no evidence of patient-specific or universal RBV thresholds that were associated with hypotension. Analysis using the kappa statistic showed that concordance of RBV and hypotension (that is, RBV falling prior to hypotensive episodes rather than rising or remaining stable) was no greater than chance. RBV and rate of change in RBV slopes did not predict hypotension as a dichotomous outcome, and were not correlated with MAP or SBP whether autocorrelation was corrected for or neglected. Substituting rate of change in RBV (RBV slopes) for absolute RBV values did not improve predictive power. CONCLUSIONS: These results suggest that strategies based on online RBV monitoring are unlikely to reduce hypotension in intermittent hemodialysis for ARF that is delivered through central venous catheters.     

Ionized calcium levels during liver transplantation

Plasma ionized calcium and total calcium concentrations were measured during 26 liver transplant operations. The level of ionized calcium decreased during the early part of the operation, reaching its lowest point during the anhepatic period, but rose again after revascularization of the new liver. Calcium chloride was given with the aim of reversing these decreases, which were associated with the use of blood products preserved in citrate-phosphate-dextrose anti-coagulant-containing adenine (CPD-A). Ionic hypocalcaemia is a result of intra-operative citrate loading in the presence of poor or absent (during the anhepatic phase) liver function; aggressive correction of low ionized calcium levels, especially during the early stages of the operation, is required to prevent this effect.     

Continuous arteriovenous hemodiafiltration: an aggressive approach to the management of acute renal failure

Continuous arteriovenous hemodiafiltration (CAVHD) offers a modified therapeutic approach to the patient with acute renal failure. The system employs a hollow-fiber dialyzer, whose perfusion is dependent on the patient's BP. Peritoneal dialysis solution is infused through the dialysate ports in a direction countercurrent to blood flow at a rate of 500 to 1,500 mL/h. Five complex patients with acute renal failure were treated with CAVHD for periods ranging from two to 40 days. Urea clearances approached 37 L/d, and in stable patients, the BUN was maintained at 40 to 60 mg/dL and serum creatinine 1.4 to 4.0 mg/dL. Ultrafiltration up to 1 L/h could be obtained without difficulty. CAVHD is a safe and technically simple procedure that is particularly suitable for hemodynamically unstable patients with ongoing needs for fluid removal.     

Continuous venovenous hemofiltration: an alternative to continuous arteriovenous hemofiltration and hemodiafiltration in acute renal failure

Continuous venovenous hemofiltration (CVVH) has been used as an alternative to continuous arteriovenous hemofiltration (CAVH) and hemodiafiltration (CAVHD) in the management of critically ill patients with acute renal failure. This report describes our experience with the first 25 patients treated with CVVH at our institution. Vascular access was obtained through a single dual-lumen venous catheter. A blood pump was used to provide ultrafiltration pressure. An ultrafiltrate pump was incorporated to ensure predictable ultrafiltrate production rates. Safety features in the extracorporeal circuit included a venous drip chamber with bubble detector and an in-line pressure monitor. CVVH was initiated by a nephrologist and dialysis nurse and was maintained by the intensive care unit (ICU) nursing staff. Fifteen females and 10 males received CVVH therapy for a total of 193.5 days (average, 7.7 +/- 10.3 days; range, 0.5 to 48 days). Four of the 25 patients (16%) survived and were discharged from the hospital. Four additional patients (16%) survived the acute phase of their illness, but died from complications of their primary disease before discharge from the hospital. The mean weight change during CVVH was -7.9 +/- 7.0 kg (range, -26.5 to +2.9 kg). Metabolic waste products and electrolytes were adequately controlled by CVVH in all but one hypercatabolic patient. The mean heparin dose required was 6.5 +/- 4.2 U/kg/h and was adjusted to prevent filter clotting rather than to achieve a predetermined activated partial thromboplastin time (PTT). The median PTT was 35.8 seconds (range, 22.0 to 100; control, 19.5 to 29.5 seconds). Four episodes of volume-responsive hypotension occurred during the 193.5 treatment days. Only one patient experienced a hemorrhagic complication during CVVH. No patient experienced a complication related to vascular access. Twelve of 111 total hemofilters were changed because of clot formation. CVVH was well tolerated by patients and managed efficiently by the ICU nursing staff.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ionized calcium concentration in maintenance hemodialysis patients.

Since numerous formulae for "adjusted" total calcium and "calculated" ionized calcium are used in clinical practice, serum total and ionised calcium concentrations were measured in 20 hemodialysis patients with a wide range of serum total calcium and albumin concentrations. Patients were evaluated pre- and post-dialysis to document the effect of pH. Pre-dialysis total calcium varied from 1.70 to 3.17 mmol/L (mean 2.52 +/- 0.08) and a very close correlation between total and ionized calcium was found (r = 0.842; p less than 0.001) with 50.2% being in the ionized form. Dialysis did not alter this relationship despite a significant increase in pH (0.09; p less than 0.01). A normal volunteer group also demonstrated a similar correlation between total and ionized calcium and while the non-ionized calcium concentration was positively and significantly correlated to the serum albumin concentration (r = 0.629; p less than 0.01) this was not the case in the dialysis patients, although the serum albumin range was much greater (18 to 46 g/L). These results suggest that the percentage of total calcium in the ionized form in dialysis patients is not different from the normal population and that minor changes in pH and albumin may not be as important as has previously been believed. While direct measurement is preferable, halving of the total calcium is a simple prediction of the ionized fraction.     

不同血液净化方法对尿毒症患者甲状旁腺素水平的影响

目的比较联机血液透析滤过（HDF）和常规血液透析（HD）对尿毒症患者甲状旁腺素（iPTH）水平的影响。方法选择我院血液净化中心2004年6月至2006年12月期间透析龄超过9个月且iPTH明显升高的尿毒症患者60例,其中男38例、女22例,平均年龄43．5岁,平均透析龄（18．6±9．3）月。将患者随机分为HDF组和HD组,每组30例。两组患者每周均透析三次,HDF组为1次HDF、2次HD,每次透析4h。HDF组使用F60滤过器;HD组使用F6HPS透析器,统一低分子肝素抗凝。检测透析前后患者血液血肌酐（SCr）、血尿素氮（BUN）及iPTH水平并计算其清除百分率。结果SCr与BUN清除率在HD组分别为（70.6％±3．2％）和（74．2%±4．0％）,在HDF组分别为（71．8％±2．3％）和（76．2%±3．8％）,两组之间差异无统计学意义。HD组血iPTH值透析前后无显著差异,清除率仅为（1．7%±0．9%）,而HDF组iPTH的清除率为（32．8％±7．8％）,该组透析前后溶质浓度及清除率的差异均有统计学意义。结论两种血液净化治疗方式对小分子物质的清除效果无差异,但HDF对中分子物质（iPTH）的清除效果明显优于HD。定期HDF有利于iPTH的清除、防止iPTH异常导致的钙磷代谢紊乱、降低代谢性骨病等并发症的发生率。     

The influence of hemodialysis on serum sialic acid levels in chronic renal failure

Background. It has been observed that there is an increase in serum sialic acid level in chronic renal diseases and endstage renal failure requiring hemodialysis, and the hemodialysis procedure causes increased cytokine production. Thus, it is expected that hemodialysis causes increases in the serum levels of acute phase reactants and sialic acid. Nevertheless, the changes in serum sialic acid level in hemodialysis have not been examined sufficiently. In our study, we examined the effect of hemodialysis on serum sialic acid level. Methods. A total of 54 patients on hemodialysis therapy for chronic renal failure (32 men; 22 women) were examined. The patients were evaluated in four groups according to their age, sex, duration of hemodialysis, and whether they were diabetic. Serum sialic acid levels before and after hemodialysis, done with a hemophane membrane, were measured by the thiobarbituric acid method described by Warren. Results. The serum sialic acid levels of chronic renal failure patients requiring hemodialysis were increased with respect to the healthy control group, independent of age, duration of therapy, and whether there was accompanying diabetes. Hemodialysis did not provide clearance of sialic acid; to the contrary, it caused an insignificant increase in serum sialic acid levels. Conclusions. In chronic renal failure, the improved serum sialic acid level probably reaches a definite value, and this value is not affected by factors such as diabetes, age, or sex. Serum sialic acid level is minimally influenced by hemodialysis performed with a hemophane membrane. Received: August 20, 2001 / Accepted: May 10, 2002     

肾移植后继发移植肾淀粉样变一例

我们成功运用持续静脉-静脉血液滤过(CVVH)抢救1例出生3 d的1.6 kg急性肾竭衰早产儿,这是目前国内文献所能查到的接受血液净化治疗的体质量最轻的新生儿.     

Continuous renal replacement therapy in acute renal failure

The management of acute renal failure in the critically ill patient is extremely variable and there are no published standards for the provision of renal replacement therapy in this population. Continuous renal replacement therapy seems to be the treatment of choice because of its superior metabolic and hemodynamic control. There is better organ protection by continuous treatment but no evidence for better survival or renal recovery due to continuous treatment. The debate about optimal membrane as well as about optimal dialysis dose is ongoing. An effluent flow rate of at least 35 ml/kg/h as well as lower BUN level at treatment initiation seem to be necessary to provide better survival rate. Peritoneal dialysis is a less suitable option in continuous renal replacement of the adult intensive care patient but hybrid methods such as extended daily dialysis and sustained low efficient daily dialysis need consideration with respect to continuous hemofiltration/dialysis.