Establishing the euvolemic state in hemodialysis patients -the so called "dry weight"- is an important clinical conundrum in every nephrologist's daily practice. Underestimation of dry weight (with excessive ultrafiltration) results in dialysis-induced hypotension. Currently used methods to establish dry weight, including clinical assessment, bio-impedance spectroscopy and online relative blood volume (RBV) measurements, all have their limitations. RBV measurement reflects changes in blood volume during dialysis without providing any information about the initial hydration status, or the initial absolute blood volume (ABV). Recently, researchers proposed a new method to calculate ABV, by using the principle of dilution-indicator with RBV measurement. In a small cohort study they identified a total blood volume threshold of 65 millilitres per kilogram dry weight predicting for intra-dialytic hypotension associated symptoms. The goal of current clinical trial is to re-investigate the accuracy of the above-described method and to confirm the hypothesis of a critical threshold of 65 ml blood volume per kg dry weight in haemodialysis patients. Researchers will compare adjustment of dry weight based on the ABV measurement with standard care to see if dialysis-induced hypotension will be reduced.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
59
adjustment of dry weight based on absolute blood volume measurement
HagaZiekenhuis
The Hague, Netherlands
difference in the incidence of intradialytic hypotension-associated adverse events between the intervention and control group
The incidence of intradialytic hypotension-associated adverse events (IHAAE) will be compared at baseline and after intervention, using questionnaires. Participants will undergo a 4-week run-in period to assess baseline incidence. The incidence of IHAAE will be calculated by dividing the number of dialysis treatments with one or more symptoms attributable to IHAAE as a percentage of the total number of dialysis treatments with a completed questionnaire. After randomization and the intervention, the occurence of IHAAE will be measured in both arms for another four weeks. Differences in incidence of IHAAE between groups will be analyzed using ANCOVA, adjusting for baseline IHAAE, pre-dialysis blood pressure and the use of anti-hypertensive agents. IHAAE is defined as a systolic blood pressure \< 90 mmHg Either symptomatic or asymptomatic, or solely symptoms associated to (impeding) hypotension like dizziness, lightheadedness, sweating, cramps or visuel disturbances.
Time frame: 10 weeks
Baseline incidence of intradialytic hypotension associated adverse events (IHAAE) in the entire study population.
Eligible participants will undergo a 4-week run-in period to assess baseline incidence of IHAAE, using questionnaires. The incidence of IHAAE will be calculated by dividing the number of dialysis treatments with one or more symptoms attributable to IHAAE as a percentage of by the total number of dialysis treatments with a completed questionnaire.
Time frame: baseline
Reproducibility of absolute blood volume measurement
Absolute blood volume (ABV) will be measured twice in the entire study population, at the start of two mid-weekly hemodialysis treatments. We will investigate the correlation between these two test results, using Bland Altman Analysis.
Time frame: 2 weeks
Correlation of absolute blood volume measurement with other diagnostic tests to determine blood volume
We will calculate antropomorphic blood volume in the whole study population, using the Nadler's formula. We will randomly select 10 participants for ABV measurement with the reference method.This technique is based on the isotope-dilution principal using I-251 radiolabeled human serum albumin. Adverse events due to the infusion of radioactive labelled albumin are very rare (0.01-0.1%, \<0.01 % anaphylactic reactions). For a 70kg-patient the dose will be 0,02 millisievert. This falls within risk category I according to the International Commission on Radiological Protection (ICRP). This is the lowest risk category with a statistical probability of less than five in a million to develop radiation induced cancer. Annual background radiation level in the Netherlands is about 2,5 mSv. We will correlate the results of these diagnostic tests to our ABV measurement, using Bland Altman analysis.
Time frame: 2 weeks
Sensitivity, specificity
We will use the values of absolute volume measurement and incidence of IHAAE to calculate sensitivity, specificity of the previously defined critical threshold of normalized blood volume of 65 ml/kg for the occurrence of IHAAE.
Time frame: 10 weeks
positive predictive value, negative predictive value
We will use the values of absolute volume measurement and incidence of IHAAE to calculate positive and negative predictive value of the previously defined critical threshold of normalized blood volume of 65 ml/kg for the occurrence of IHAAE.
Time frame: 10 weeks
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