Pergamon Appl. Radiat. lsot. Vol. 49, No. 5/6, pp. 607-610, 1998

~. 1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain

P I I : S0969-8043(97)00192-9 0969-8043/98 $19.00 + 0.00

The Use of Bioimpedance Spectroscopy to Monitor Water Changes Induced by Rehydration in Young Children with

Abnormal Water Disturbances Associated with Diarrheal Disease

A N D R E A M E Y E R 2, M A N O L O M A Z A R I E G O S j, N O E L W. S O L O M O N S I and P E T E R F U R S T 2.

'Center for Studies of Sensory Impairment, Aging and Metabolism--CeSSIAM, Diagonal 21, 19-19 Zona 11, Guatemala City, Guatemala 01011 and 2The Department of Biological Chemistry and

Nutrition, Hohenheim University, Garbenstrasse 30, 70599 Stuttgart, Germany

Introduction

One of the most claimed uses of bioelectrical impedance has been the evaluation of fluid status and therefore the ability to monitor fluid changes associated with therapy. It has been the capability of bioelectrical impedance spectroscopy (BIS) not just to determine body water, but also to discrimi- nate fluid disturbances across membranes (intra- extracellular fluid distribution), that has attracted the attention of nutrition and medical researchers and practitioners. As the current methodology for the evaluation of fluid distribution is not readily available everywhere, the incorporation of BIS as a non-invasive technique offers the opportunity of introducing body composition techniques into medicine, principally in the care of acutely ill patients.

On the other hand, although the use of BIS has been disseminated and focused in the First World on the study fluid imbalances associated with cardiac, renal metabolic and medical problems, etc., very little is known about its application to relevant health problems in developing countries. Severe malnutrition and acute dehydration, still leading causes of morbidity and mortality in the child population of developing countries, may offer a unique opportunity of evaluating the usefulness of BIS in assessing fluid changes.

Acute dehydration represents a clinical condition characterized by a significant reduction in body fluids, at the expense of the extracellular compart- ment. The severity of the clinical picture corre- sponds to the degree of fluid loss. The principal

*To whom all correspondence should be addressed.

causes of dehydration in developing countries is still infectious diarrheal disease caused principally by viruses, bacteria, including cholera, etc. Fluid therapy is lifesaving in these cases, as the recovery can be seen in a very short period of time. In this study we have evaluated the use of BIS to detect and monitor fluid imbalances in dehydrated chil- dren.

Perhaps the four main challenges for the appli- cation of BIS in child populations are:

1. use of BIS in young and sick children (cooperation constraint);

2. the relatively small size of the conductor length in very young children;

3. the abnormality in water distribution in children with hydrational disorders;

4. the small magnitude of the changes associated with fluid therapy.

Methods

Population

A group of 20 children, 12 boys and 8 girls, were admitted to the General Hospital "San Juan de Dios" in Guatemala City, for acute dehydration associated to diarrheal disease, ranging in severity from moderate to severe dehydration (hypovolemic shock). Nine out of the 20 children were categorized on admission as having moderate dehydration and 11 as severely dehydrated. The age of the groups ranged from 3 to 47 months and the weights from 4 to 20 kg, respectively. Before discharge of the child from hospital the recovery status was evaluated. The children were classified either as fully recovered (n = 8) or as partly recovered (n = 12) from

607

608 Andrea Meyer et al.

Table 1. Mean differences ~ between initial and final measurement for each segment for Rtcw (~) of children who fully recovered from dehydration

n = 8 In i t ia l m e a s u r e m e n t 5 ± S D F ina l m e a s u r e m e n t g ± S D p - V a l u e "~ M a g n i t u d e o f changes C h a n g e s ( % )

W h o l e - b o d y 855.6 + 104.5 660 .9 + 82.1 + - 194.75 - 22.8 A r m l e s s - b o d y 433 .8 + 71.7 343 .0 + 36.4 + - 90 .80 - 20.9 A r m 447 .0 + 64.1 349.3 + 37.5 + - 97 .75 - 21.9 Leg 349 .0 + 74.1 268.3 + 49 .0 + - 80 .64 23.1 T r u n k ips i l a te ra l 84.8 + 6.7 67 .9 + 10.1 + - 16.96 - 20.0 T r u n k med ia l 59.2 _+ 3.4 48.5 + 4.1 + - 10.67 - 18.0

" C o m p a r i s o n be tween m e a n s by pa i r ed t- test : + = p < 0 .05 is cons ide red s ignif icant ; n.s. = no t s ignif icant .

dehydration. For comparison purposes, a group of six fully recovered children from acute malnutrition were recruited from a Nutrition Unit. At the time of the evaluation, the control children were in good clinical condition. The age of the comparison group ranged from 7 to 33 months, and their weight from 4 to 10 kg.

out. Correlation coefficients were calculated between the first and second measurement.

Mean comparisons of BIS parameters between the control and study group were carried out by using an independent t-test. In all cases the significant p value was adjusted by the Bonferroni correction (McGuigan, 1990).

Procedures

Weight and BIS indices were measured at admission and at intervals, as an indicator of recovery from dehydration. BIS measurements were made using a Xitron 4000B analyzer (Xitron Technologies, CA, USA), at the level of whole body and segmental measurements at the level of arm, trunk, leg and armless-body as reported in the literature (Mazariegos el al., 1996). Measurements were taken in duplicates, one after another. In order to obtain proper measurements in young, sick children with very little cooperation, it was necessary to hold the child by using a wrapping blanket, only leaving exposed the specific segment being assessed. For the purposes of this study, bandage electrodes (BIS4000 electrodes, Xitron Technologies, CA, USA), which are selfadhesive gummed aluminum foil, were kept in position for the planned longitudinal measurements until recovery. Usually, most children recovered within the first 6 h of fluid therapy.

The control group was assessed for weight, height and BIS on only two occasions, 4 h apart in order to determine the variability of impedance measurements under stable conditions (with no fluid interventions) in a period of time similar to that usually taken to recover in the study group.

Statistical data analysis. Mean comparisons were done between the initial and the final measurement (at discharge or when the child was considered recovered), by using a paired t-test. Analysis of variance for repeated measurements was also carried

Results

Tables 1 and 2 show the comparisons between the initial and final BIS indices for both whole body and segmental approaches, for the study group. There was an overall decrease in Rzcvv associated with recovery and there seems to be a different pattern between those children who were fully or partly recovered, with the marked changes in the fully recovered group. The mean decline expressed as percent of the baseline values at the level of whole body for REcw in both the fully and partly recovered group were - 2 2 . 8 % and - 7 . 9 % ranging for all segments from - 18.0% to - 2 3 . 1 % and from - 9 . 7 % to - 1 2 . 0 % , respectively. The greatest changes were seen at the level of whole body and leg and the minimum change was seen at the level of trunk. There was also a trend towards greater changes in the group with severe dehydration in comparison to the moderate and the control group.

The mean differences between initial and final BIS indices ranged for R~cw from - 1 8 . 2 % to 52.1%, with the greatest changes at the level of whole-body (data not shown). Independent of the outcome of treatment no identical pattern of changes could be observed. In some children R,cw increased between initial and final measurement, in others a decrease or no change was noticed.

Figures 1 and 2 show the complex impedance loci at initial treatment stage and during recovery in a child who was fully recovered and in one child who was partly recovered.

T a b l e 2. M e a n differences" be tween in i t ia l and f inal m e a s u r e m e n t for each segmen t for REcw (1)) o f ch i l d r en w h o par t ly r ecovered f rom d e h y d r a t i o n

n = 12 Ini t ia l m e a s u r e m e n t .7 + S D F ina l m e a s u r e m e n t ~7 _+ S D p - V a l u e "~ M a g n i t u d e o f changes C h a n g e s ( % )

W h o l e - b o d y 871.5 + 117.1 803.0 + 127.2 + - 6 8 . 5 1 - 7.9 A r m l e s s - b o d y 508.3 + 135.3 457.1 + 93 .5 + - 51.21 - 10.1 A r m 446 .2 _+ 108.8 392 .6 _% 108.0 + -- 53 .69 - 12.0 Leg 427 .2 + 138.1 385 .6 + 101.7 + -- 41 .63 - 9 .7 T r u n k ips i l a te ra l 85 .03 + 11.62 75 .0 + 12.7 + - 9 .99 - t 1.7 T r u n k med ia l 61 .0 + 10.1 54.2 + 8.6 + - 6 .84 - I 1.2

" C o m p a r i s o n be tween m e a n s by pa i r ed t- test : + = p _< 0 .05 is cons ide red s ignif icant ; n.s. = no t s ignif icant .

160 --

140 -- B A

120 - -

• -= I 0 0 --

8 0 -

6 0 - -

4 0 - -

20 --

0 500 600 700 800 900 1000

Resistance [ohms]

Fig. 1. Complex impedance loci of the whole-body of a fully recovered child: before treatment (A), after 1 h i.v. treatment

(B), after 2.5 b (C) and after finishing with treatment.

Use of BIS to monitor water changes in young children

12 - [ ] initial -r [ ] final

W h e n REC w is adjusted by the length of the segment (BIS-Index-REcw [cm2/f~]), a clear trend toward greater changes in the fully recovered group with respect to the partly recovered or control group is seen (Fig. 3).

Figure 4 shows the relationship between BIS changes in terms of REC w and weight change during fluid therapy. Weight gain was associated with REcw decrease. The Pearson correlation co- efficient was highly significant at the level of 0.82 (p<0 .001 ) . Interestingly the same pattern was observed in both whole body and segmental measurements (r values ranging from 0.54 to 0.87, corresponding to the armless body approach the highest r value).

The pattern of changes in terms of other BIS indices (intracellular resistance, and membrane capacitance), was much less consistent, and therefore we are presenting only data on REcw.

9 0 --

8 0 --

7 0 --

~ 60

"g 50

~ 4o

~ 3o

~ 2o

io

o I I i 4 0 0 5 0 0 6 0 0 7 0 0

Resistance [ohms]

Fig. 2. Complex impedance loci of the whole-body of a partly recovered child: before treatment (A), after 1 h i.v. treatment (B), after 2.5 h (C) and after finishing with

treatment.

609

E 3 1o

8

2

r, o

i I

fully partly recovered recovered

apparently healthy

Fig. 3. Initial and final BIS-Index-R~cw between fully recovered and partly recovered children and the control

group.

D i s c u s s i o n

After performing more than one thousand measurements in the present study we have been able to demonstrate the feasibility of using BIS in a young and sick child population. The magnitude and direction of changes of REcw were according to what we expected (a decrease of about 20%). Gaining of fluid and thence recovery from dehy- dration (through oral or intravenous infusions) induced a pattern toward reduction in REcw. The decrease in ECW induced by dehydration usually leads toward an increase in REcw, therefore fluid therapy should show changes in the opposite direction. This pattern has been previously ob- served by using single frequency analyzers (Mc- Donald et al., 1993; Arango, 1987), but now this study demonstrated that the most consistent change corresponds to the extracellular compart- ment. R,cw determinations did not show a consist- ent pattern, and therefore its use in this specific population is still uncertain.

The changes documented in the present study were greater than those observed in the control group. The magnitude of changes followed a stepwise pattern: was null in the control group, more obvious in the group partly recovered and very marked in the fully

50 -- Changes in weight [kg]

F ° ' l " , ~ " I I I l - 0 . 1 0 . 0 m ~ 0 . 2 0 .3 0 . 4 n0[ .5

- 5 0 ~- • ~ , , ~ 0 . 6

o

- ' ° ° - Z L . 4 _ _ •

- 1 5 0 -- • ~ nu .~ •

-200 - y = 3 7 8 . 7 9 x - 13 .9

o~

~= -250 - ~" r = 0.82

-300 -

- 3 5 0 --

Fig. 4. Weight changes vs changes in REcw.

I

0 . 7

610 Andrea Meyer et al.

recovered group. This suggests that BIS was capable in detecting actual fluid gains and shifts associated with hydrational therapy.

Kanai et al. (1987) have published some obser- vations which in some way confirmed the theoretical basis of BIS. This author observed in his study subjects that fluid shifts (fluid loss) were accompanied by shifts in the complex impedance loci. The present study presents two cases as examples: a subject fully recovered and another partly recovered. In both cases there was a shift of the complex impedance loci toward the left, however the shift was greater in the fully recovered subject. This indicates that fluid recovery induced changes in the impedance charac- teristics of the study group.

Given that segmental measurements were compar- able to whole body approach, their use in young and sick children can make the technique easier and also assure reliability when monitoring fluid shifts associated with treatment.

Based on the findings, we are confident that a nomogramic relationship can be established between estimates of water distribution (ECW and ICW) using gold standard methods and BIS-REcw, in this particular population. However further studies are needed to investigate the limitations of the remaining BIS parameters which according to our preliminary analysis are very unstable.

Acknowledgements--We would like to thank the authorities and the medical staff of the Emergency Unit at The General Hospital "San Juan de Dios", in Guatemala City, for their support. We are thanking also the instrumental support of Mr James Mathie from Xitron Technologies Inc for their support giving as a loan the BIS-4000B instrument and providing the disposable electrodes used in the present study.

References

Arango, T. (1987) Measurements of electrical resistance and reactance in dehydrated children and first changes after rehydration. Thesis, San Carlos, Guatemala: Faculty of Medicine, University of San Carlos, pp. 1-70.

Kanai, H., Haeno, M. and Sakomoto, K. (1987) Electrical measurement of fluid distribution in legs and arms. Med. Progr. Tech. 12, 159-170.

Mazariegos, M. et al. (1996), Bioelectrical impedance spectroscopy (BIS) in young children with acute and semi-acute hydration disorders: potentials and limi- tations. In Proceedings in vivo Body Composition Studies, Maim6, September 1996. Appl. Radiat. Isot.. to be published.

McGuigan, T. J. (1990) Experimental psychology. In Methods of Research, 5th edn, pp. 139-146. Prentice Hall, Englewood Cliffs, NJ.

McDonald, J. J. et al. (1993) Bioimpedance monitoring of rehydration in cholera. Lancet 341, 104%1051.