腹膜透析及包装用高分子材料的应用现状

为了概括腹膜透析及包装用高分子材料的发展与应用,就作为CAPD重要组成部分的透析液包装和透析导管的发展状况,以及材料、加工和应用中的相关问题进行综述。     

Normalization of Dialysis Dose for Daily Dialysis

The equilibrated Kt/V (eKtV) is widely used in hemodialysis (HD) as a measure of the intensity (magnitude) of an individual dialysis treatment. Adequate eKt/V for thrice‐weekly hemodialysis (twHD) has been extensively studied, and a value in the range 1.0 – 1.1 per treatment (3.0 – 3.3 weekly) is generally considered to represent adequate therapy for this specific frequency of dialysis. However, for other schedules, summing eKt/V's and time‐averaging the clearance is not appropriate. This was first demonstrated several years ago by the observation that a weekly eKt/V of 2.0 in continuous ambulatory peritoneal dialysis (CAPD) is therapeutically equal to a weekly eKt/V of 3.0 in twHD. That paradox has been resolved by the standard Kt/V (stdKt/V), which accounts for the first order nature of solute removal by dialysis, and which correctly predicts a normalized weekly stdKt/V of 2.0 for both CAPD and twHD. The equivalent renal clearance (EKR) has also been advanced as a method to normalize dose for varying treatment schedules. However, mathematical consideration shows that EKR is an exact time‐averaged clearance. Analysis of data reported for daily dialysis by Piccoli et al. in the present issue of Hemodialysis International shows that the EKR_ct/V calculated for daily dialysis is identical to the sum of eKt/V's for the individual dialyses. We therefore conclude that EKR is not a suitable parameter for normalizing the dialysis dose, because it fails to reflect the effect of dialysis frequency in HD therapy.     

Psychological Symptoms Are Greater in Caregivers of Patients on Hemodialysis Than Those of Peritoneal Dialysis

Background: The purpose of this study was to evaluate and compare psychosocial characteristics in caregiving relatives (caregivers) of hemodialysis (HD) and peritoneal dialysis (PD) patients. Methods: Thirty‐three caregivers (17 women, 16 men) of HD patients, 27 caregivers (11 women, 16 men) of PD patients, and a control group of 49 subjects who do not care for family members with chronic illness (23 women, 26 men) are included in this study. The brief symptom inventory (BSI), social disability schedule (SDS), and brief disability questionnaire (BDQ) were used for the psychosocial evaluation. Results: The mean age, men‐to‐women ratios, duration of education, and distribution of marital status did not differ significantly among the three groups. In addition, dialysis duration and distribution of caregiver type were not different between the HD and PD groups. Although the mean global severity index scores of the three groups were similar, somatization and depression scores from BSI subitems were greater in the HD group than the scores of the PD and control groups. Although the mean SDS and BDQ scores were higher in the HD group, the differences did not achieve statistical significance. BSI subitems such as somatization, obsession–compulsion, interpersonal sensitivity, depression, and anxiety were positively correlated among themselves. Hostility and somatization were negatively correlated with age and education, respectively. Nevertheless, somatization was positively correlated with age. Social disability was negatively correlated with duration of education. Conclusion: Somatization and depression are greater in the caregivers of center HD patients compared to PD and control groups. According to the findings of this study, we suggest that caregiving family members of dialysis patients especially on HD also should be evaluated for psychosocial problems and supported as needed. Further studies are needed to explore whether psychosocial parameters of caregivers predict outcomes for caregivers and patients.     

Restless leg syndrome presenting as chronic severe limb pain in a dialysis patient

“Chronic pain” is a commonly reported symptom among hemodialysis patients. Despite its high prevalence and the poor health-related quality of life associated with it, chronic pain remains an ineffectively assessed and managed entity in dialysis patients. We report a case of a 55-year-old gentleman on maintenance hemodialysis who presented with 3 months history of “excruciating flitting and fleeting type” of pain largely involving both lower limbs and occasionally neck, shoulder, chest, and upper limbs. The pain was so intolerable that it even triggered suicidal intentions in the patient. Common causes of chronic pain in dialysis patients were considered, but the initial history and clinical examination remained elusive. The patient was empirically started on oral analgesics, benzodiazepines, calcitriol, and levocarnitine supplementation but had no significant effect on his symptoms. A comprehensive repeat clinical history revealed the nocturnal periodicity of symptoms, specific aggravation of pain with inactivity, and its temporary relief with movement. This helped us narrow down the diagnosis to restless leg syndrome (RLS) amidst the myriad causes of chronic pain in dialysis patients. The “constant urge to move the legs” which is the defining characteristic of RLS was inconspicuous in our patient and excruciating pain was the predominant manifestation. This atypical presentation of RLS with agonizing pain involving multiple sites of the body led to a delay in the diagnosis and initiation of appropriate therapeutic measures. The patient had a dramatic response to therapy with dopamine agonists and withdrawal of the drug led to reappearance of his symptoms which further confirmed the diagnosis of RLS. RLS should be considered in the evaluation of chronic pain in dialysis patients and renal health care providers should familiarize themselves with the varied atypical, forme fruste manifestations of RLS to avoid diagnostic delay of this disabling but treatable condition.     

The natural fluid nitrous oxide—an option as substitute for low temperature synthetic refrigerants

A theoretical investigation was performed concerning the coefficient of performance (COP) of cascade refrigerating systems using N₂O as refrigerant for the low temperature cascade stage and various natural refrigerants like ammonia, propane, propene, carbon dioxide and nitrous oxide itself for the high temperature stage. The basis of the comparison was a conventional R23/R134a-cascade refrigerating system for heat rejection temperatures of +55, +35 and +25 °C for air cooling, cooling tower water cooling and city water cooling, respectively. It can be stated that such an application of N₂O at the primary stage and ammonia or hydrocarbons as refrigerants at the secondary stage in refrigerating systems achieves similar COP-values compared to the R23/R134a-cascade refrigerating system, whereas CO₂ and N₂O in a transcritical cycle in general perform worse.An application of N₂O in a two-stage compression cycle with interstage injection and city water cooling at low and high interstage temperatures has a nearly equal COP as a conventional R23/R134a-cascade refrigerating system and is an interesting alternative for small laboratory refrigerating systems.     

Sugarcane bagasses sewage sludge compost as a plant growth substrate and an option for waste management

The possible utilization of sugarcane bagasses sewage sludge-based compost (BSC) as a substitution for widely using expensive peat in growth media for a horticultural crop, lettuce (Lactuca sativa L.), was evaluated. Five different treatments having different percentages of BSC and peat were established. Percentages of BSC addition to peat were 0, 10, 25, 40, and 60%?v/v, respectively. Physical and chemical characteristics of different growth media were undertaken. Plant growth parameters and nutrient composition of lettuce plants were determined. In general, the proposed growing media created with peat and BSC had adequate physical and chemical properties and notable contents of plant nutrients, mainly P, K, Ca, and Mg. Moreover, BSC addition to peat enhanced the nutrient content in lettuce plants compared to plants grown in peat-only substrate. The highest increases of growth and yield parameters were obtained in the treatment having BSC and peat at 25 and 75% of the total volume, respectively. The shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight obtained from the media having BSC and peat at 25 and 75% were increased by 53.25, 43.32, 36.27, and 56.88%, respectively, compared to peat control. In addition, the mixture with the most BSC (60%) gave the greatest contents of K, Mg, Ca, Cu, Zn, Cr, and Pb. Trace element concentrations in plant tissues grown in media with BSC and peat were far below than the ranges considered phytotoxic for plants. These results indicate that these BSC-based media is a viable alternative to expensive peat for cultivation of lettuce.     

Hospitalizations before and after initiation of chronic hemodialysis

Hospitalization rate is high in patients on chronic hemodialysis (HD). We investigated whether initiation of HD changes the rate and length of hospitalization. We analyzed hospitalizations in HD patients in one hospital over 15 years. We compared annual rate and length of hospitalizations, both presented as mean (95% confidence interval [CI]) between the pre-HD and HD period. Three hundred ninety-two patients, 98% men, 59% diabetic, and 66.3 ± 11.2 years old at the onset of HD, had 1016 hospitalizations in the pre-HD period (60.0 ± 42.9 months) and 1627 hospitalizations in the HD period (32.5 ± 25.9 months). Higher values were found in the HD than the pre-HD period for rate, (pre-HD 0.557 [95% CI 0.473-0.611], HD 2.198 [95% CI 1.997-2.399] admissions/[patient-year], P<0.001) and length (pre-HD 4.63 [95% CI 3.71-5.55], HD 28.07 [95% CI 23.55-32.59] days/patient-year], P<0.001) of hospitalizations for all causes, cardiac disease, infections, vascular access, peripheral vascular disease, metabolic disturbances, gastrointestinal diseases, and miscellaneous conditions, mainly respiratory illness and malignancy. Similar differences were found when we compared the year before and the year after the start of HD. Diabetics had higher all cause rate and length of hospitalizations than non-diabetics in the pre-HD and HD periods. The rate and length of hospitalizations was higher in the HD than the pre-HD period for both HD-specific conditions and conditions encountered in both HD and general populations. Study of factors specific to HD that may affect these conditions should constitute the first step toward improving the morbidity of patients on HD.     

A Comparative Study of C‐Reactive Protein Plasma Levels in Patients on Hemodialysis and Peritoneal Dialysis

In dialysis patients, C‐reactive protein (CRP), a well‐recognized marker of inflammation, predicts mortality. Higher levels have been described in hemodialysis (HD) patients as compared with peritoneal dialysis (PD) patients. Our aim was to determine, based on CRP plasma levels, the degree of inflammation in HD patients using low‐permeability polysulfone membranes and relatively pure dialysate, and that in PD patients. A secondary objective was to study factors associated with hypoalbuminemia and inflammation in both populations. We studied 69 stable patients on dialysis (32 on HD and 37 on PD). The mean age was 69.9 ± 8.2 years, and the mean time on dialysis was 27 months. The two populations were comparable for overall and cardiovascular comorbidities. Nephelometry was used to measure CRP plasma levels (normal levels < 0.6 mg/dL). The Kt/V_urea, corrected for residual renal clearance, and the equivalent of protein nitrogen appearance (PNA) were also calculated. Of the patients studied, 53% showed CRP plasma levels higher than 0.6 mg/dL; in 36%, the levels were higher than 1 mg/dL. No significant differences in these percentages were noted between the two dialysis groups. Patients with CRP levels higher than 1 mg/dL showed lower serum albumin, iron, hemoglobin, and transferrin levels, and higher ferritin values and leukocyte counts. Under logistic regression analysis, CRP levels higher and lower than 1 mg/dL were significantly associated with serum albumin [p = 0.01; odds ratio (OR): 0.15], iron (p = 0.006; OR: 0.96), transferrin (p = 0.004; OR: 0.97), and hemoglobin (p = 0.02; OR: 0.67). Serum albumin levels were significantly lower in PD patients. Under regression analysis, serum albumin levels correlated with cholesterol (r: 0.25; p = 0.04), serum iron (r: 0.5; p = 0.0001), transferrin (r: 0.3; p = 0.015), ultrafiltration capacity (r: 0.42; p = 0.008), and CRP values above 0.6 mg/dL (r: –0.65; p = 0.001). In conclusion, the frequent elevation of CRP plasma levels observed in both HD and PD patients suggests the presence of a silent inflammatory state. Hemodialysis performed with biocompatible, low‐permeability membranes is not associated with higher CRP plasma levels than those seen in PD. In both groups, hypoalbuminemia is related to CRP level. Levels of serum albumin, slightly lower in PD patients, are also related to peritoneal ultrafiltration capacity.     

Importance of early dialysis for acute renal failure after an open-heart surgery

Coronary artery disease is a major cause of death in patients with a renal dysfunction. Among the patients who undergo coronary artery bypass grafting, renal dysfunction is known to be a major predictor of in-hospital and out-of-hospital mortality. From 2004 to 2007, we performed elective open-heart surgeries on 2380 patients in whom there was no primary renal failure. Of those patients, only 185 in whom acute renal failure (ARF) was developed were included in the study. The patients were divided into 2 groups: a late dialysis group (n=90) and an early dialysis group (n=95). The mean age of the patients was 62.3±6.4 in the late dialysis group and 64.5±5.2 in the early dialysis group. There were 32 female and 58 male patients in the late dialysis group and 36 female and 59 male patients in the early dialysis group. Acute renal failure developed only in 185 patients out of 2380 open-heart surgery patients. The overall mortality in the 2380 open-heart surgery patients was 1.97%. Mortality among the ARF patients was 5.9%. However, there was no significant difference in hospital mortality between the 2 groups. Major complications, such as postoperative pneumonia, prolonged ventilation time, arrhythmia, the number of times postoperative hemodialysis was performed, development of chronic renal failure, time spent in the intensive care unit and the period of hospitalization, sepsis, and low cardiac output, were significantly higher in the late dialysis group. There was no difference in mortality between the 2 groups. Early dialysis for open-heart surgery patients who develop ARF postoperatively does not decrease mortality. However, it decreases morbidity, the amount of time spent in intensive care, and the period of hospitalization and thus reduces patient costs.     

A real-life example of choosing an inherently safer process option

While choosing an inherently safer alternative may seem straightforward, sometimes what seems to be the most obvious alternative may not provide the best risk reduction. The process designer must maintain a broad perspective to be able to recognize all potential hazards when evaluating design options. All aspects of operation such as start-up, shut-down, utility failure, as well as normal operation should be considered. Choosing the inherently safer option is best accomplished early in the option selection phase of a project; however, recycle back to the option selection phase may be needed if an option is not thoroughly evaluated early in the process. In this paper, a project to supply ammonia to a catalytic reactor will be reviewed. During the course of the project, an "inherently safer" alternative was selected and later discarded due to issues uncovered during the detail design phase. The final option chosen will be compared to (1) the original design and (2) the initial "inherently safer" alternative. The final option was inherently safer than both the original design and the initial "inherently safer" alternative even though the design team initially believed that it would not be.     

The influence of socioeconomic status on patient survival on chronic dialysis

Socioeconomic status (SES) has been linked to worse end‐stage kidney disease survival. The effect of SES on survival on chronic dialysis, including the impact of transplantation, was examined. A retrospective, observational study investigated the association of SES with dialysis patient survival, with censoring at time of transplantation. Adult patients commencing dialysis from 1990 to 2009 in an Irish tertiary center received a spatial SES score using the 2011 Pobal Haase‐Pratschke Deprivation Index and were compared by quartile. Cox proportional hazard models and Kaplan–Meier survival analysis examined any association of SES with survival. The 1794 patients included had a median follow‐up of 3.8 years. Patients in the lowest SES area quartile were significantly younger than the highest, mean age 56.7 vs. 59 years, P = 0.006, respectively. There was no association between SES area score and survival in an unadjusted model (hazard ratio [HR] 1.00, 95% confidence interval [CI] 0.99–1.01). Survival in the highest SES area quartile was superior to the lowest SES in a multivariable adjusted model including age, gender, and dialysis modality (HR 0.83, 95% CI 0.70–0.99, P = 0.04). These results were only mildly attenuated by censoring at time of transplantation (highest SES area quartile deprived vs. lowest SES area quartile, HR 0.85, 95% CI 0.70–1.03, P = 0.09). Superior patient survival was identified in the highest SES areas compared with the lowest following age‐adjusted analyses, despite the older population in the most affluent areas. Further research should focus on identifying modifiable targets for intervention that account for this socioeconomic‐related survival advantage.     

The Glycemic Indices in Dialysis Evaluation (GIDE) study: Comparative measures of glycemic control in diabetic dialysis patients

The validity of hemoglobin A1c (HgbA1c) is undergoing increasing scrutiny in the advanced CKD/ESRD (chronic kidney disease/end‐stage renal disease) population, where it appears to be discordant from other glycemic indices. In the Glycemic Indices in Dialysis Evaluation (GIDE) Study, we sought to assess correlation of HgbA1c with casual glucose, glycated albumin, and serum fructosamine in a large group of diabetic patients on dialysis. From 26 dialysis facilities in the United States, 1758 diabetic patients (hemodialysis = 1476, peritoneal dialysis = 282) were enrolled in the first quarter of 2013. The distributions of HgbA1c and the other glycemic indices were analyzed. Intra‐patient coefficients of variation and correlations among the four glycemic indices were determined. Patients with low HgbA1c values were both on higher erythropoietin (ESA) doses and more anemic. Serum glucose exhibited the highest intra‐patient variability over a 3‐month period; variability was modest among the other glycemic indices, and least with HgbA1c. Statistical analyses inclusive of all glycemic markers indicated modest to strong correlations. HgbA1c was more likely to be in the target range than glycated albumin or serum fructosamine, suggesting factors which may or may not be directly related to glycemic control, including anemia, ESA management, and iron administration, in interpreting HgbA1c values. These initial results from the GIDE Study clarify laboratory correlations among glycemic indices and add to concerns about reliance on HgbA1c in patients with diabetes and advanced kidney disease.     

Prevalence of the metabolic syndrome in an incident dialysis population

The National Heart, Lung, and Blood Institute's National Cholesterol Education Program 2001 Adult Treatment Panel III report defined the metabolic syndrome as having at least 3 of the following 5 criteria: abdominal obesity, elevated triglyceride levels, low high-density lipoprotein cholesterol levels, an elevated blood pressure, and an elevated fasting glucose. Evidence is accumulating to suggest that the metabolic syndrome predisposes to cardiovascular disease (CVD). End-stage kidney disease (ESKD) patients requiring dialysis have a substantially elevated risk of CVD morbidity and mortality. Dialysis patients' increased risk can be partially explained by traditional and nontraditional risk factors. The prevalence of the metabolic syndrome in dialysis patients is unknown. This retrospective, cross-sectional study of 202 incident dialysis patients examined the prevalence of the metabolic syndrome at the time of renal replacement therapy initiation. The study group was compared with all incident dialysis patients in 2002 on file with the U.S. Renal Data System. Females represented 39.1% of the study population. Blacks composed 34.7% of the study group. Diabetes was the etiology of ESKD in 44.6% of our patients. Surrogate criteria were used for the Adult Treatment Panel III risk factors of abdominal obesity and elevated fasting glucose levels. Overall, the prevalence of the metabolic syndrome was 69.3% in our population and was especially prevalent among diabetic, female, and white ESKD patients. Study limitations included the use of surrogate markers for 2 criteria of the metabolic syndrome and dependence on the Medical Evidence Report (Form 2728) for baseline characteristics. In summary, the metabolic syndrome is highly prevalent in incident dialysis patients.     

Determinants of C-reactive protein in chronic hemodialysis patients: relevance of dialysis catheter utilization

Biomarkers of inflammation, especially C-reactive protein (CRP), have been consistently shown to predict poor outcomes in chronic hemodialysis (CHD) patients. However, the determinants of CRP and the value of its monitoring in CHD patients have not been well defined. We conducted a retrospective cohort study to evaluate possible determinants of the inflammatory response in CHD patients with a focus on dialysis catheter utilization. Monthly CRP were measured in 128 prevalent CHD patients (mean age 56.6 years [range 19-90], 68% African Americans, 39% diabetics [DM]) over a mean follow-up of 12 months (range 2-26 months). There were a total of 2405 CRP measurements (median 5.7 mg/L; interquartile range [IQR] 2.4-16.6 mg/L). The presence of a dialysis catheter (p<0.002), cardiovascular disease (p=0.01), male gender (p=0.005), higher white blood cell count (p<0.0001), elevated phosphorus (p=0.03), and lower cholesterol (p=0.02) and albumin (p<0.0001) concentrations were independent predictors of elevated CRP in the multivariate analysis. Additionally, CRP levels were significantly associated with the presence of a catheter, when comparing the levels before and after catheter insertion (p=0.002) as well as before and after catheter removal (p=0.009). Our results indicate that the presence of a hemodialysis catheter is an independent determinant of an exaggerated inflammatory response in CHD patients representing a potentially modifiable risk factor.     

Some indications from instability results about the effectiveness of wall heating as a control option for channel flow

This paper is a review of some of our recent work on the effect of wall heating on the stability of laminar flow in a channel. The summary of our results, some of them unexpected, is as follows. Viscosity stratification has very little effect on transient growth, whereas it results in linear mode stabilising or destabilising by an order of magnitude. It has hitherto been accepted that heat diffusivity does not affect stability. This is however true only for linear instability, transient growth is affected by an order of magnitude. Unusually, the growth is spanwise-independent and not in the form of streamwise vortices. It is also shown that flow is destabilised by secondary modes as the viscosity ratio increases. However, the viscosity ratio has no role in the selection of the pattern of Λ vortices.