Effect of Ultrafiltration During Cardiopulmonary Bypass for Pediatric Cardiac Surgery

The effect of ultrafiltration during cardiopulmonary bypass (CPB) was evaluated for correcting ventricular septal defects with associated pulmonary hypertension in patients less than 18 months old. Interleukin (IL)-6 and IL-8 concentrations in the blood, ultrafiltrate, and urine were measured. The blood IL-6 concentration increased to 128.4 ± 20.2 pg/ml by the end of surgery, which is lower than the concentration seen in adult patients (273.1 ± 48.2 pg/ml, p < 0.02). The blood IL-8 concentration was not significantly different than that of adults. The total amounts of excreted IL-6 in the ultrafiltrate and urine during CPB were 11.5 ± 0.32 pg/kg and 0.32 ± 0.07 pg/kg, respectively (p < 0.05). The total amounts of excreted IL-8 in the ultrafiltrate and urine were 4.64 ± 0.69 pg/kg and 1.92 ± 0.56 pg/kg, respectively (p < 0.05). No differences were seen in these values for excretion between children and adults. We conclude that ultrafiltration during CPB in pediatric patients is more effective in removing proinflammatory cytokines than in adults and more effective than renal filtration alone.     

The dual effect of urinary macromolecules on the crystallization of calcium oxalate endogenous in urine

Summary The nucleation-promoting and growth-inhibiting activities of urinary macromolecules on the crystallization of calcium oxalate endogenous in urine of stoneformers and normal controls were studied by freezing the ultrafiltrate and retentate fractions of concentrated whole urine (pH 5.3, 1,250 mosmol/kg). Among the normal controls, macromolecules nominally of 10–20 kDa showed nucleation-promoting and growth-inhibiting activities; the 5–10 kDa population was incapable of such effects but did cooperate with molecules >10 kDa in enhancing the effect. In the case of stone-formers, molecules in the nominal ranges of 5–10 kDa and 10–20 kDa when considered separately were not active in the aspects studied but collectively could cooperate to produce pronounced effects. Application of the test to urine ultrafiltrate reconstituted with polyanionic macromolecules recovered from urine indicated that molecules from stoneformers were more powerful than those from normal controls in bringing about promotion of nucleation and inhibition of growth of crystals from urinary calcium oxalate.     

Meta-Analysis of Ultrafiltration versus Diuretics Treatment Option for Overload Volume Reduction in Patients with Acute Decompensated Heart Failure

Introduction

Although diuretics are mainly used for the treatment of acute decompensated heart failure (ADHF), inadequate responses and complications have led to the use of extracorporeal ultrafiltration (UF) as an alternative strategy for reducing volume overloads in patients with ADHF.

Objective

The aim of our study is to perform meta-analysis of the results obtained from studies on extracorporeal venous ultrafiltration and compare them with those of standard diuretic treatment for overload volume reduction in acute decompensated heart failure.

Methods

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases were systematically searched using a pre‑specified criterion. Pooled estimates of outcomes after 48 h (weight change, serum creatinine level, and all-cause mortality) were computed using random effect models. Pooled weighted mean differences were calculated for weight loss and change in creatinine level, whereas a pooled risk ratio was used for the analysis of binary all-cause mortality outcome.

Results

A total of nine studies, involving 613 patients, met the eligibility criteria. The mean weight loss in patients who underwent UF therapy was 1.78 kg [95% Confidence Interval (CI): −2.65 to −0.91 kg; p < 0.001) more than those who received standard diuretic therapy. The post-intervention creatinine level, however, was not significantly different (mean change = −0.25 mg/dL; 95% CI: −0.56 to 0.06 mg/dL; p = 0.112). The risk of all-cause mortality persisted in patients treated with UF compared with patients treated with standard diuretics (Pooled RR = 1.00; 95% CI: 0.64–1.56; p = 0.993).

Conclusion

Compared with standard diuretic therapy, UF treatment for overload volume reduction in individuals suffering from ADHF, resulted in significant reduction of body weight within 48 h. However, no significant decrease of serum creatinine level or reduction of all-cause mortality was observed.     

血液透析机超滤功能合理调校周期的探讨

目的 探讨血液透析机超滤功能合理的调校周期.方法 选取首都医科大学附属北京同仁医院血液透析中心28台血液透析机,测定不同时间的超滤误差值.按测定时间将样本分为5组,比较不同时间的超滤误差值;按机器品牌将样本分为2组,比较不同品牌之间的超滤误差值. 结果 ①不同测定时间的5组数据之间比较.机器刚校准后的超滤误差值与6个月后、9个月后和12个月后的超滤误差值比较均有统计学差异（F=16.062,P＜0.05）;3个月后超滤误差值与6个月后、9个月后和12个月后的超滤误差值比较均有统计学差异（F=16.062,P＜0.05）;②不同品牌之间比较.费森尤斯组与贝朗组在9个月后（F=21.017,t=2.261,P=0.042）、12个月后（F=28.119,t=2.364,P=0.026）的超滤误差值比较有统计学差异.结论 每6个月进行一次透析机超滤功能的校准,较为合理.     

高原地区体外循环应用超滤对儿童术后右心室功能的影响

目的　探讨高原地区体外循环 (CPB)中应用血液超滤技术对心内直视手术后右心室功能的保护作用。方法　选择在海拔 370 0m开展的CPB心脏手术患者 12例 ,根据CPB过程中有无应用血液超滤技术 ,将患者分成血液超滤组和对照组 ,分别于CPB前、CPB结束时以及CPB后 1h、3h、6h、12h、2 4h ,测定肺动脉平均压 (MPAP)、右心房压 (RAP)、右心室舒张末容积指数 (RVEDVI)、右心室射血分数 (RVEF)、心脏指数 (CI)、右心室每搏容量指数 (RVSI)和肺血管阻力指数 (PVRI)。结果　CPB结束和CPB后 6h内 ,对照组MPAP、RVEDVI以及RAP均较CPB前明显升高 (P <0 0 5 ) ,而RVEF、CI和RVSI较CPB前降低 (P <0 0 5 ) ;CPB后 12h对照组MPAP、RVEDVI以及RAP均逐渐减低 ,但RVEF、CI和RVSI仍未高于CPB前 ;血液超滤组RVEF、CI和RVSI在CPB后各时间点均显著高于对照组 (P <0 0 5 )。结论　高原地区在CPB下施行心内直视手术后早期 ,右心室心肌收缩力显著降低 ,右心室的泵血功能受损 ;CPB中应用血液超滤技术有利于CPB后心脏泵血功能的恢复。     

A dual-chambered hemodialyzer for convection-enhanced hemodialysis

Convective clearance during hemodialysis (HD) improves dialysis outcomes in kidney failure patients, and, thus, trials have been undertaken to increase convective mass transfer, which is directly related to internal filtration rates. The authors designed a new hemodialyzer to increase the internal filtration rates, and here describe the hemodialytic efficacy of the devised unit. The developed dual‐chambered hemodialyzer (DCH) contains two separate chambers for dialysate flow within a single housing. By placing a flow restrictor on the dialysate stream between these two chambers, dialysate pressures are regulated independently. Dialysate is maintained at a higher pressure than blood pressure in one chamber, and at a lower pressure in the other chamber. The dialysis performance of the DCH was investigated using an acute canine renal failure model. Urea and creatinine reductions and albumin loss were monitored, and forward and backward filtration rates were measured. No procedurally related malfunction was encountered, and animals remained stable without any complications. Urea and creatinine reductions after 4‐h dialysis treatments were 75.2 ± 6.5% and 67.7 ± 8.9%, respectively. Post‐treatment total protein and albumin levels remained at pretreatment values. Total filtration volume was 4.98 ± 0.5 L over 4 h, whereas the corresponding backfiltration (BF) volume was 4.77 ± 0.6 L. The developed dual‐chamber dialyzer has the benefit of providing independent control of forward filtration and BF rates. HD using this dialyzer provides a straightforward means of increasing the internal filtration and convective dose.     

不同超滤对先心病婴幼儿胶体渗透压的影响

目的探讨婴幼儿心脏手术中应用常规超滤（CUF）、改良超滤（MUF）及其联合应用对血浆胶体渗透压（COP）及围术期恢复时间的影响。方法60例在体外循环（CPB）下行心脏直视手术（体重〈10kg）的婴幼儿，随机分为常规超滤组（CUF组，n=20）、改良超滤组（MUF组，n=20）、联合超滤组（CM组，n=20），观测不同时间点（麻醉诱导前、麻醉诱导后、转机前、CPB5min、主动脉阻断后、CPB30min、停机时、CPB结束15min、入ICU即刻、ICU2h、ICU6h、ICU12h、ICU24h）的血浆COP，对比三组患儿的呼吸机辅助时间、ICU停留时间、住院时间。结果CM组和CUF组的COP水平在CPB30min、停机时均高于MUF组（P〈0．05）；MUF组和CM组在CPB结束15min、入ICU即刻、ICU2h时的COP水平显著高于CUF组（P〈0．05）；MUF组和CM组无显著性差异（P〉0．05）。CM组较其他两组显著缩短了呼吸机辅助时间、ICU停留时间和住院时间。结论联合应用CUF和MUF不仅在一定程度上提高了患儿CPB进行时的COP水平，而且进一步改善了CPB后的COP水平，患儿术后脱机拔管时间提前，监护室和医院停留时间缩短。     

A new method for chemical analysis of faeces

By using a centriflo membrane cone filter it has become possible to obtain an ultrafiltrate from a 24-h stool specimen. In this faecal fluid several clinical chemical parameters were analysed, such as pH, osmolality, creatinine, sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate and lactate. Reference intervals for these substances were obtained in healthy individuals. The data of this control group were compared to those of patients with diarrhoea due to active inflammatory bowel disease, irritable bowel syndrome, lactose intolerance and persons with an ileostomy.     

Risks of peritoneal membrane failure in children undergoing long-term peritoneal dialysis

Children undergoing long-term peritoneal dialysis are at risk for membrane injury, necessitating conversion to hemodialysis. We analyzed the incidence and risk factors for membrane failure (inadequate ultrafiltration with or without peritoneal adhesions and decreased peritoneal surface area) in 68 children maintained with peritoneal dialysis for more than 3 months at our institution. The overall incidence of membrane failure was 16.2% (11/68). Kaplan-Meier estimates of peritoneal membrane survival were 88% at 24 months, 72% at 36 months, 65% at 48 months, and 52% at 60 months. Logistic regression analysis demonstrated that the risk of membrane failure increased with the number of episodes of peritonitis (odds ratio 1.61). The rate of peritonitis was 1 per 7.02 patient months in children who developed membrane failure compared with 1 per 9.18 patient months in children without membrane failures but the rate of peritonitis was not predictive of membrane failure (P=0.09). Multiple logistic regression analysis demonstrated that peritonitis caused byPseudomonas aeruginosa or alpha streptococcal organisms were independent predictors of membrane failure. We conclude that peritoneal membrane survival declines substantially with time on peritoneal dialysis and that membrane failure is associated with peritonitis, particularly peritonitis caused byPseudomonas aeruginosa and alpha streptococcal organisms. The mechanism(s) of membrane injury are unknown but may be related to the inflammatory response initiated during peritonitis.     

Ultrafiltration and Backfiltration during Hemodialysis

Abstract: Ultrafiltration is the pressure-driven process by which hemodialysis removes excess fluid from renal failure patients. Despite substantial improvements in hemodialysis technology, three significant problems related to ultrafiltration remain: ultrafiltration volume control, ultrafiltration rate control, and backfiltration. Ultrafiltration volume control is complicated by the effects of plasma protein adsorption, hematocrit, and coagulation parameters on membrane performance. Furthermore, previously developed equations relating the ultrafiltration rate and the transmembrane pressure are not applicable to high-flux dialyzers, high blood flow rates, and erythropoietin therapy. Regulation of the ultrafiltration rate to avoid hypotension, cramps and other intradialytic complications is complicated by inaccurate estimates of dry weight and patient-to-patient differences in vascular refilling rates. Continuous monitoring of circulating blood volume during hemodialysis may enable a better understanding of the role of blood volume in triggering intradialytic symptoms and allow determination of optimal ultrafiltration rate profiles for hemodialysis. Backfiltration can occur as a direct result of ultrafiltration control and results in transport of bacterial products from dialysate to blood. By examining these problems from an engineering perspective, the authors hope to clarify what can and cannot be prevented by understanding and manipulating the fluid dynamics of ultrafiltration.