Downs JH|Veldman F|Kassier S
Poster presentation at the Critical Care Congress
Objective: To compare excess fluid to be removed in HD as estimated by the HD staff versus the volume measured per multiple frequency BIA.
- A prospective, non-randomized observational study was conducted.
- Repeated measures of 24 BIA pre- and post HD measurements were conducted over 3 months on 20 chronic HD subjects (50% male; ages 21 to 63 yrs) at the KEH HD unit. A total of 960 pre-and post BIA measurements were measured.
- The Quadscan 4000® (Bodystat) multiple frequency (5 to 200Hz) BIA machine was used to measure BIA.
- Ethics approval was obtained from the UKZN Ethic’s Committee; Ethics no.: BE041/14
- Data were analysed using repeated measures ANOVA (Statistica v7).
- There was no significant difference when combined effects including days were considered, but there was a clinically significant difference (1.29L) between the excess fluid measured per BIA vs the HD staff estimate. This difference was more pronounced in subjects with a body fat % (BF) ≥30% and a BMI >28 kg/m2 vs their leaner counterparts, (the combined effect accounting for days was p= 0.780; but the difference between the 2 groups was p=0.00*; Fig. 1a, b).
- Subjects with a body fat % ≥30% and a BMI >28 kg/m2, had a negative 3rd water space vs those with lower BF % and BMI’s. There was no significant difference when combined effects including days were considered but there was a significant difference between the two groups (p=0.000*; Fig. 1c).
- All subjects’ intracellular fluid was below the normal range despite their hydration status. There was no significant difference when combined effects including days were considered but there was a significant difference between pre and norm (p=0.003*).
- The prediction (illness) marker showed a post dialysis improved trend.
- There was a clinically significant difference between the excess fluid measured per BIA vs the HD staff estimate.
- All the subjects irrespective of whether they were overhydrated or dehydrated, had an intracellular fluid % below the normal range. We postulate that this patient group has an excessive sodium intake, resulting in fluid shifts from the intra- to the extracellular space.
- The reason for a survival benefit of a higher body fat % & BMI in HD patients has alluded scientists for the past 20 years. Subjects with a body fat percentage ≥30% and a BMI >28 kg/m2, had a negative 3rd water space vs those with lower BF % and BMI’s. We postulate that this is an important factor in improving this sub-groups better survival amongst HD patients, and that it is due to greater perspiration, and consequent higher water and sodium losses in this group versus their leaner counterparts.
- BIA is an invaluable tool for guiding both HD staff and patients towards an optimal fluid status in HD patients, as both extracellular and 3rd water space can be accurately measured and monitored.