Once a patient has been prescribed dialysis by a nephrologist, specialists must calculate how much water to remove from the body in order to achieve the patient’s dry weight. Ideally, this weight allows normal blood pressure to be maintained without using antihypertensive medication.
The field of nephrology focuses largely on body water and dialysis. Dialysis is a treatment that filters the blood of all excess fluid, toxins, and waste and is prescribed when the kidneys can no longer do those processes on their own. Dialysis treatments must be performed multiple times a week, for hours at a time, for the rest of the patient’s life.
Clinical Methods for determining dry weight include:
Body composition formulas are generally recommended for estimating total body water and blood pressure monitoring is used to pinpoint the amount of water that must be removed to return blood pressure to normal.
As you would imagine, accurately determining how much fluid is considered excessive for one person is difficult. For this reason, nephrologists rely heavily on changes in body water to diagnose the frequency of dialysis, determine how much water needs to be filtered out, and to maintain blood volume in their patients. However, many of the methods are indirect, based on expected ratios based on height and weight, are expensive or are based on trial and error. They are also invasive and cause discomfort for the patient.
InBody devices are non-invasive and tests are completed in less than 60 seconds. InBody data can be used to fluctuations and fine tune the process of bringing dialysis patients to the appropriate dry weight. InBody devices can also be used to determine where a patient is holding excess water and track fluid movement. This accurate, reproducible information doesn’t rely on empirical data and therefore, reflects the patient.
Biometric data is gathered by InBody’s four core technologies:
Multi-frequency Measurements are able to measure extracellular water (ECW) and intracellular water (ICW), providing an accurate and quantitative measure of total body water.
Direct Segmental Measurement divides the body into five separate cylinders and measures the impedance for each segment.
The 8-Point Tactile System with thumb electrodes offers reliable reproducibility by ensuring that tests are always beginning at the same anatomical starting points.
These technologies combined eliminate any need for empirical data(assumptions for body composition based on factors like age, gender or ethnicity).
Want to know more about InBody's four core technologies?
InBody Result Sheets quickly generate accurate outputs like dry weight, fluid distribution (ICW and ECW), and total body water measured in pounds.
This makes it easier to safely bring patients to the appropriate dry weight. Additional outputs can assess risks for other morbidities commonly associated with kidney failure, such as heart disease and diabetes. While professionals are more accurately able to determine and bring the patient to dry weight, the patient can also see the difference that their treatment is making.
The InBody 3.0 was used to assess fluid measures in both hemodialysis and peritoneal dialysis patients in order to guide dry weight determination. Through the use of multiple frequency technology, the InBody is able to distinguish between the intracellular and extracellular compartments. This study shows the value of using these objective measures and the ratios between fluid compartments in order to establish a goal weight.
Tsai (2004) Evaluation of ideal body weight in dialysis patients through bioelectrical impedance analysis
In a group of patients with OSA in Hemodialysis, the effects of both compression stockings (CS) and continuous positive airway pressure (CPAP) were assessed to see improvements in neck circumference, Apnea-hypopnea index (AHI), and fluid retention in the body. After each intervention, it was seen that CPAP displayed superior performance to the CS. However, CS did reduce AHI by avoiding fluid retention in the legs, keeping it in the intracellular compartment of the trunk. This emphasizes a feasible alternative treatment for hemodialysis patients with OSA.
Silva (2017) Impact of Compression Stockings vs. Continuous Positive Airway Pressure on Overnight Fluid Shift and Obstructive Sleep Apnea among Patients on Hemodialysis
This study evaluated the effectiveness of segmental BIA to track chronic fluid overload and outcomes in end stage renal disease patients on hemodialysis. Researchers confirmed BIA to be an accurate method for tracking fluid in end state renal disease patients. Findings indicated that those with an ECW/TBW > 0.400 had higher systolic blood pressure and had a higher morbidity rate, emphasizing that chronic fluid overload can be a predictor for death.
Kim (2017) Monitoring Volume Status Using Bioelectrical Impedance Analysis in Chronic Hemodialysis Patients