Paul Heidenheim

The Role of Support in Influencing Outcome of End-Stage Renal Disease

An important part of health behavior variability is a supportive environment. This paper examines the concept and discusses its application to a general and geriatric home dialysis population. Social environment is analyzed along three interrelated dimensions: social support, social integration, and social network. The authors conclude that a multimethod approach for assessing environmental support is preferred over a single-item index. Furthermore, a supportive interpersonal environment is important for patients and family, both as a preventive agent and as a protective buffer against the impact of ESRD related stress.

Optimal timing of initiation of chronic hemodialysis

Despite the availability of clinical guidelines for the timing of dialysis initiation in both the United States and Canada, patients continue to start dialysis at very low levels of predicted glomerular filtration rate (GFR). A cross‐sectional study was performed to determine the demographic and clinical characteristics of patients who started hemodialysis, their level of GFR, and mortality at 1 and 2 years following the initiation of dialysis. Retrospective data were collected on all eligible patients who commenced chronic hemodialysis in 1 tertiary care center in Canada from March 2001 to February 2005. Only those patients who had been followed by a nephrologist in the chronic kidney disease clinic before dialysis initiation were included (n=271). Seventeen percent of patients started hemodialysis late (GFR<5 mL/min/1.73 m2). Compared with the group of patients who started dialysis earlier, the late start group were significantly younger (p=0.008), had more females (p=0.013), more employed (p=0.051), less cardiac (p<0.001), and peripheral vascular disease (p=0.031), and were taking medication for hypertension (p=0.041). Serum albumin was lower in the late start group (p=0.023). At year 1, there was no difference in mortality rate while at year 2, the earlier the dialysis, the greater the mortality rate (p=0.022). After adjustment for demographic variables and comorbidities, only antihypertensive use had an independent but weak association with the 2 year mortality. Adjustment for all these variables eliminated the significant association noted for the 2 year mortality in the early versus late dialysis start. The survival benefit for late versus early dialysis start appears to be multifactorial and relates to a preponderance of clinical and demographic factors favoring a lengthened survival occurring in the late dialysis group. Our survival benefit findings suggest the premorbid health condition is a more important determinant of 2 year survival than the timing of dialysis initiation.

Cystatin C Levels in Functionally Anephric Patients Undergoing Dialysis: The Effect of Different Methods and Intensities

BACKGROUND AND OBJECTIVES Cystatin C, a low molecular weight protein, is produced by nucleated cells, filtered by glomeruli, and degraded by tubules at a constant rate. Its serum concentration has been proposed as a marker of GFR. Its size should make it dialyzable. It is hypothesized that serum cystatin C levels are influenced by the method and intensity of dialysis received. DESIGN This is a cross-sectional pilot study of cystatin C in functionally anephric dialysis patients. It was measured predialysis in 14 patients on conventional (3 to 5 h, 3 x wk) hemodialysis; eight on nocturnal hemodialysis (three to seven nights, 6 to 8 h); three on daily hemodialysis (6 d, 1(1/2) to 2(1/2) h); and 10 on automated peritoneal dialysis. All had urea kinetic studies and values for single pool Kt/V (Sp Kt/V), standard weekly Kt/V (Std Kt/V), and protein equivalent of nitrogen appearance (nPNA; g/kg/d). C reactive protein (CRP; mg/L) and thyroid stimulating hormone (TSH; mIU/L) were measured as factors known to influence cystatin C. RESULTS There was no correlation between cystatin C and Sp Kt/V, but there was a significant inverse linear correlation with Std Kt/V and there were significant differences between treatment modalities in cystatin C levels and in Std Kt/V. The estimation of cystatin C was reliable and stable over 3 to 6 wk and its levels uninfluenced by nPNA, CRP, or TSH. CONCLUSION Serum cystatin C levels are influenced by the method and intensity of dialysis and may have a role in treatment adequacy monitoring.

Can extracellular fluid volume expansion in hemodialysis patients be safely reduced using the hemocontrol biofeedback algorithm? A randomized trial.

Extracellular fluid volume (ECFV) expansion in hemodialysis patients is associated with increased mortality. Attempts to remove excess fluid often result in intradialytic hypotension (IDH). Blood volume monitoring has been used to aid selection of ultrafiltration rates and dialysate conductivity to minimize IDH. Automating ultrafiltration and dialysate conductivity using the Hemocontrol Biofeedback System (HBS) has reduced IDH in IDH-prone subjects. We undertook a randomized controlled trial to determine if the HBS could safely reduce ECFV in ECF-expanded subjects. Patients with ECFV >45% of total body water were randomized to receive hemodialysis by either HBS or best clinical practices for 6 months. The primary endpoint was change in ECFV; exploratory variables included frequency of IDH, interdialytic weight gain, and changes in serum Na. Treatment with HBS did not result in any change in ECFV, even after multivariable adjustment. The frequency of IDH was however significantly lower with HBS when compared with best clinical practices without differences in other variables.

Measurement of extravascular lung water in hemodialysis patients using blood ultrasound velocity and optical density dilution

In hemodialysis patients, volume homeostasis is an important clinical problem. The aim is to have patients at an ideal “dry weight” postdialysis, but current methods for accurately measuring dry weight are disappointing. Krivitski et al. (ASAIO J 1998;44:M535-M540) have described a novel technique whereby extravascular lung water (EVLW) may be measured using blood ultrasound velocity and electrical impedance dilution. They have tested this method in animals and achieved agreement between obtained versus gravimetric measurements. Isotonic saline is used as a nondiffusible indicator and hypertonic (5%) saline is used as a diffusible indicator. By injecting these solutions and following their transits through the cardiopulmonary circulation, a theoretic basis for the calculation of EVLW may be derived from the cardiac output, the water transferred to blood, the amount of sodium chloride moved from blood to lung, and the increase in blood osmolality measured at the moment of osmotic equilibrium. We have used this new technique to measure EVLW for the first time in humans in 18 stable hemodialysis patients with no cardiac problems. Measurements were carried out twice in each patient, the first early in dialysis, the second toward the end of a dialysis session where fluid removal took place. The values for EVLW were 260 ± 49 ml early in dialysis and 230 ± 48 ml late in dialysis. This fall of 30 ± 45 ml was statistically significant (p = 0.011). EVLW normalized to body weight was 3.29 ± 1.0 ml/kg early and 3.02 ± 1.04 ml/kg late in dialysis, a nonsignificant difference (p − 0.073). The normalized EVLW values are almost identical to those obtained in animals (3.1 ± 1.4 ml/kg) by Krivitski et al. (see above). We conclude that this new technique can conveniently and noninvasively give an estimate of EVLW in hemodialysis patients. The clinical value of this measurement has now to be determined.

Pre to post-dialysis plasma sodium change better predicts clinical outcomes than dialysate to plasma sodium gradient in quotidian hemodialysis.

Sodium balance across a hemodialysis treatment influences interdialytic weight gain (IDWG), pre‐dialysis blood pressure, and the occurrence of intradialytic hypotension, which associate with patient morbidity and mortality. In thrice weekly conventional hemodialysis patients, the dialysate sodium minus pre‐dialysis plasma sodium concentration (δDPNa+) and the post‐dialysis minus pre‐dialysis plasma sodium (δPNa+) are surrogates of sodium balance, and are associated with both cardiovascular and all‐cause mortality. However, whether δDPNa+ or δPNa+ better predicts clinical outcomes in quotidian dialysis is unknown. We performed a retrospective analysis of clinical and demographic data from the Southwestern Ontario Regional Home Hemodialysis program, of all patients since 1985. In frequent nocturnal hemodialysis, δPNa+ was superior to δDPNa+ in predicting IDWG (R2 = 0.223 vs. 0.020, P = 0.002 vs. 0.76), intradialytic change in systolic (R2 = 0.100 vs. 0.002, P = 0.02 vs. 0.16) and diastolic (R2 = 0.066 vs. 0.019, P = 0.02 vs. 0.06) blood pressure, and ultrafiltration rate (R2 = 0.296 vs. 0.036, P = 0.001 vs. 0.52). In short hours daily hemodialysis, δDPNa+ was better than δPNa+ in predicting intradialytic change in diastolic blood pressure (R2 = 0.101 vs. 0.003, P = 0.02 vs. 0.13). However, δPNa+ was better than δDPNa+ in predicting IDWG (R2 = 0.105 vs. 0.019, P = 0.04 vs. 0.68) and pre‐dialysis systolic blood pressure (R2 = 0.103 vs. 0.007, P = 0.02 vs. 0.82). We also found that the intradialytic blood pressure fall was greater in frequent nocturnal hemodialysis patients than in short hours daily patients, when exposed to a dialysate to plasma sodium gradient. These results provide a basis for design of prospective trials in quotidian dialysis modalities, to determine the effect of sodium balance on cardiovascular outcome.

Quality of Life in Peritoneal Dialysis Patients: Instruments and Application

For the past 25 years, dialysis has been advocated as an artificial replacement therapy for the functional loss of kidneys. Thousands of patients with chronic renal failure have been kept alive who otherwise would-have died. At present, in excess of 80 000 persons in the United States are on dialysis, a dramatic increase from the 2398 of 15 years ago [1]. This increase, in large measure, is due to the technological and treatment advances in renal replacement therapy. However, technologies such as automated dialysis systems [2, 3], bacteriologically safe catheters [4], and modified peritoneal dialysis procedures such as CAPD [5] or its automated nocturnal form, ‘prolonged dwell’ peritoneal dialysis [6], do more than sustain life. They enhance patients’ physical status and tolerance for home treatment [7] and free them from the constraints of extracorporeal hemodialysis [8], thus contributing to overall improvement in patients’ cognitive acuity and psychosocial functioning [9–12].

Is There a Necessity for Individual Blood Water Corrections when Conductivity-Based Access Blood Flow Measurements Are Made?

Background/Aims:Access blood water flow rate (Qaw) can be measured during hemodialysis using an online effective ionic dialysance (EID) methodology. Fresenius employ this methodology in their 2008K dialysis machine. The machine computer converts Qaw to an access blood flow rate (Fresenius Qa) using a generic blood water constant (BWC). We wished to validate this BWC. Methods: 18 patients had Fresenius Qa measurements using the EID and these were compared with a ‘gold standard’ ultrasound dilution methodology (Transonic Qa). Qa values were also obtained by removing the BWC from Fresenius Qa values to obtain the Qaw and recorrecting it with individualized patient factors using hematocrit and total protein values (HctTp Qa). The measurements were repeated after 1 h. Results:There were no significant differences between Fresenius and Transonic, nor between HctTp and Transonic Qa values (p > 0.17). There were strong correlations between both sets of values (r > 0.856; p < 0.001). There was a significant correlation between the pairs of Transonic Qa values (r = 0.823; p < 0.007), but not for Fresenius Qa pairs (r = 0.573; p > 0.07). It was surmised that the BWC was not valid post-dialysis. Conclusion:The generic BWC is comparable to individualized blood water correction factors when Qa measures are made early in dialysis and prior to ultrafiltration treatment.