Radioisotope blood volume measurement in hemodialysis patients

Hemodialysis International

Leimbach³

et al. 2015

The reduction of blood volume below a critical threshold is assumed to trigger intradialytic morbid events (IME). Recently, we presented a simple method to determine the absolute blood volume during routine hemodialysis (HD) carried out without blood sampling and without injection of dyes or radiolabeled markers. Such information could be used to detect excessive volume reduction during HD and to prevent IME. Therefore, we performed a pilot study in IME-prone patients to identify the absolute blood volume at which they developed clinical symptoms. A volume of 240 mL of ultrapure dialysate was automatically infused into the extracorporeal circulation using the bolus function of a commercial online hemodiafiltration machine incorporating a blood volume monitor (BVM). The increase in relative blood volume (RBV) caused by the infusion was measured and used to determine the absolute blood volume at that time. The blood volume per kilogram body mass at the time of symptomatic IME was also determined. All IME-prone patients of a single-dialysis center were included in the study. Ten out of 12 patients became symptomatic at a specific blood volume between 65 and 56 mL/kg (mean 62 mL/kg) whereas RBV showed a wide scatter (82-97%). A specific blood volume of 65 mL/kg seems to represent the threshold for IME by this method. The technique could be completely automated without altering the hardware of the dialysis device. Present feedback systems for automated blood volume-controlled ultrafiltration could be adapted to maintain absolute blood volume above this critical volume to safely prevent volume-dependent IME.

Section: Discussionsupporting

confidence: 76%

Determination of the critical absolute blood volume for intradialytic morbid events

Kron

Hemodialysis International

Leimbach³

et al. 2015

“…For example, the magnitude of priming solution infused while establishing the extracorporeal circulation depends on the size of the dialyzer and whether the patient is connected with or without “hemorrhage.” And the rinse back at the end of dialysis is also variable. These uncertainties may help to explain some paradoxical observations reported elsewhere …”

Section: Discussionmentioning

confidence: 88%

“…Unlike other studies where measurements were compared with conditions before and after dialysis, the comparison in this study was carried out for corresponding time points and experimental conditions during dialysis. This has important consequences for blood volumes and concentrations.…”

Section: Discussionmentioning

confidence: 99%

“…This discrepancy is due to the limited repeatability of absolute volume measurements compared with the high repeatability of online concentration measurements in the range of 1%. 1,2 Unlike other studies where measurements were compared with conditions before and after dialysis, 22 the comparison in this study was carried out for corresponding time points and experimental conditions during dialysis. This has important consequences for blood volumes and concentrations.…”

Section: Discussionmentioning

confidence: 99%

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Concordance of absolute and relative plasma volume changes and stability of F_cells in routine hemodialysis

Hemodialysis International

Ribitsch

Schilcher

et al. 2015

Central hematocrit (H c ) measurements are currently used to track the degree of ultrafiltrationinduced hemoconcentration with the aim to detect and prevent excessive intravascular fluid depletion during hemodialysis (HD). Failure to maintain hemodynamic stability is commonly attributed to the misinterpretation of H c caused by the un-accountable increase in F cells , the ratio of whole body hematocrit to H c .It was the aim to examine F cells under everyday conditions in a group of stable HD patients. Absolute plasma volume (V p ) and H c were concomitantly measured during routine HD in the extracorporeal system in hourly intervals using optical means to derive relative plasma volumes from V p and H c (RPV p , RPV H ), and to calculate F cells .Thirteen patients were studied during two mid-week treatments (n=26). Both absolute V p (p<0.05) and relative plasma volumes RPV H (p<0.001) decreased during HD. V p at any time point was positively correlated to RPV H (r=0.72). Moreover, relative plasma volumes RPV H and RPV p determined by independent techniques were identical and showed negligible bias (−0.2 %) but considerable limits of agreement (−15.6 to +15.3%). F cells was in the range of 0.9±0.05 throughout HD and stable in subjects and not different from the value assumed at the beginning of HD.In conclusion, while relative plasma volumes (RPV H and RPV p ) determined by independent techniques are comparable and F cells remains constant, individual variability and limited accuracy of absolute volume measurements appears to complicate the control problem. Alternative strategies to control for excessive hemoconcentration need to be considered.

“…In 10 patients, Puri et al measured specific blood volumes of 75 and 67 ml/kg before and after dialysis, respectively [24,] while Dasselaar et al measured 81 ml/kg pre and 67 ml/kg post dialysis in 7 patients [25] when their data are normalized for body mass. …”

Section: Discussionmentioning

confidence: 99%

A Simple and Feasible Method to Determine Absolute Blood Volume in Hemodialysis Patients in Clinical Practice

Kron¹,

Leimbach³

et al. 2014

Blood Purif

Background: We developed a simple method to determine the absolute blood volume (V) during hemodialysis in everyday clinical practice and examined its relationship with volume overload, clinical relevance, and accuracy. Methods: The increase in relative blood volume (RBV_post - RBV_pre) measured before and after infusion of 240 ml of ultra-pure dialysate using the bolus function of a commercial online hemodiafiltration machine incorporating a relative blood volume monitor was applied to determine absolute blood volume. The specific blood volume (V_s, blood volume per kg body mass at dry weight, in ml/kg) was compared to volume status as assessed by bioimpedance analysis and clinical criteria. Results: The blood volume measured in 30 stable hemodialysis patients was 6.51 ± 1.70 l at the beginning, corresponding to a specific blood volume of 80.1 ± 12.8 ml/kg, and dropped to 5.84 ± 1.61 l or 72.0 ± 12.1 ml/kg at the end of the dialysis session, respectively. Specific blood volume correlated with volume status assessed both clinically and by bioimpedance analysis. Intradialytic morbid events occurred only in treatments where specific blood volume fell below 65 ml/kg. The reproducibility of the technique was better than 4% and the in vitro accuracy corresponds to a resolution in V_s of better than 1 ml/kg. Conclusion: Absolute blood volume can be easily measured at the beginning of the dialysis session using the current dialysis technology. Information about V and V_s could be a promising tool to avoid intradialytic morbid events. This technique could be completely automated without altering the hardware of currently available online dialysis devices. Therefore, it is recommended that this technique be integrated into all hemodiafiltration machines.