European Journal of Clinical Investigation (1 977) 7, 161 - 165

A reassessment of intravascular volume measurements in protein-calorie malnutrition P. FONDU, The CEMUBAC Medical Mission to IRSAC, Lwiro, Republic of Zaire, and Pediatric Department, Free Universities of Brussels Received 19 April 1976 and in revised form 21 September 1976

Abstract. Accurate determination of plasma volume is

difficult in oedematous protein -calorie malnutrition, but present studies on the equilibration of labelled red cells have shown that red cell volume measurements are valid in this syndrome. The red cell volumes have been measured in afflicted Bantu children during a refeeding programme. Expression of the results in ml/kg, ml/m2 or ml/cm is misleading and has been replaced by expressing the results as a percentage of the means of the normal values for the height. The results show that the red cell volume increase that ought to occur at the end of refeeding programme (and hence the iron requirement) is far higher than suggested by the packed cell volume. With treatment the red cell volume increases slowly. The red cell volume and plasma volume changes that occur during treatment d o not take place at the same rate. Key words. Protein-calorie malnutrition, intravascular

volumes, radioactive chromium. Introduction

Several authors have measured intravascular volumes in protein-calorie malnutrition (PCM) using Evans blue or radioactive albumin [ 1-10] . The results obtained in kwashiorkor should be interpreted with caution: as albumin may diffuse into the extravascular space, the volume of distribution may be greater than the plasma volume in oedematous patients [ l l , 121. The radioactive chromium technique measuring red cell volume (RCV) could provide more accurate results in PCM [13, 141. These studies have led to conflicting interpretations of the haematological and haemodynamic state, due to methological difficulties and partly to the problem of the choice of the appropriate standards of reference in children with a profoundly altered body composition. Our aim is t o make clear the usefulness and limitations of intravascular volume measurements in children with oedematous PCM, and to define the therapeutic implications of such studies. Correspondence: Dr P. Fondu, Department of Pediatrics, H8pital Saint-Pierre, 320 rue Haute, 1000 Brussels, Belgium.

Material and Methods

The Bantu children studied were aged 1-10 years. Details of the clinical and biological characteristics of the patients have been documented elsewhere [15-171 and are summarized in Table 1. The refeeding programme consisted of skimmed milk and local foods, without iron supplementation [ 181 . Group I consisted of twenty-eight patients studied the day after admission. On the day of admission they received nothing but tea and rice; the RCV was measured before any other blood sample was taken. The packed cell volume (PCV) was further determined every 3 days during the refeeding period. Group I1 consisted of twenty patients studied on the fourteenth day of refeeding, and group 111 of ten patients who had been refed for at least 2 months; the height gain during this period was negligible. Group IV consisted of seven well-nourished Bantu children of similar age range, whose results have been previously presented [ 161 . Informed consent was obtained from controls’ parents. Each group comprised an approximately equal number of boys and girls. No patient received a transfusion and blood samFling was kept t o a minimum. No child had malaria, sickle-cell anaemia or ankylostomiasis. The methods used have already been published [15, 161. Local growth curves were used to determine the average normal weight for height. The plasma albumin level was measured by paper electrophoresis. For the RCV determination, the children were in fasting conditions and were kept in a lying position throughout the procedure. 8 ml blood were taken into 2 ml of ACD NiH A, incubated for 30-45 min with 1 pCi/kg of SICr-chromate, then washed three times and reinjected. The radioactivity injected was determined in two weighed aliquots taken before and after the patient had been reinjected. Two to three blood samples were taken from another vein between the tenth and the sixtieth minute. To see whether there was some abnormality of red cell distribution, the radioactivity per ml of red cells in circulation 10 min after the reinjection of the labelled cells (a) was compared with the radioactivity observed in the last sample (a’). The value of the a’/a ratio was 1.01?0.008 in group I and 0.99*0.011 in the controls; neither of these ratios was significantly different from 1. In several patients studied on admission, the precordial 161

162

P. FONDU Table 1. Characteristics of children studied (mean

Weight deviation (%)*

Group

I: Patients studied on admission (n = 28) 11: Patients refed

for 14 days (n = 20)

-14

5

1.9t

-15

5

2.5

1.78 f 0.107

~

least 2 months (n = 10) IV: Controls ( R = 7)

Packed cell volume (vol %)

Serum albumin, (g/dl)

3 c 4.0 (-13 5 2.5) + 253.6

111: Patients refed for at

SEMI

f

2.09 (1.83

5

2.84 (2.16 3.55

f

f

k 5

33.4 f 0.94

0.1561 0.116)

29.1 f 1.19 ( 3 1 . 0 ~1.14) 30.8 f 1.31 (34.8 2 0.80) 40.4 f 0.99

0.186 0.178) 0.180

The values in parentheses are those observed before treatment. (patient’s weight-average normal weight for height)X 100 *Weight deviation = average normal weight for height The patient’s weight is the minimum weight (groups I and 11) o r the weight measured on day of test (groups I11 and IV). i n = 25: three patients died before their oedema completely resolved.

activity, measured continuously in the hour following reinjection, was constant between the tenth and the sixtieth minute. PCV was measured after centrifugation for 5 min in a high speed micro-capillary haematocrit centrifuge (International Micro-Capillary Centrifuge, Model MB). Assuming that A is the injected radioactivity, i the average value of the activity per ml of circulating red cells, and F the ratio of body PCV to venous PCV, following equations were used to calculate RCV and ‘plasma volume’: RCV = A / i ‘Plasma volume’ =

RCVX (1 - F X PCV)

F X PCV

The value of F was assumed to be 0.90; as it has not been directly measured in PCM, the ‘plasma volume’ values based on this assumption are conjectural. Results

The RCV, ‘plasma volume’ and PCV values are given in Table 2 . The volumes are expressed in ml/kg, the weight considered being the minimum weight observed during refeeding (groups I and 11), or the weight measured on the day the volumes were determined (groups I11 and IV). The results are also expressed as percentages of the mean of the normal values for the height (normalized RCV per cent, or RCV (%)),in the present study. The normal mean value for height is found by multiplying the average weight, in kg, of normal chldren of the same

Table 2. RCV, ‘Plasma volume’ and PCV on admission, during refeeding, and in controls (mean

Results expressed in:

RCV

ml/kg %

‘Plasma volume’

ml/kg %

PCV

vol %

I: Children studied on admission (n = 28)

11: Children

19.4 f 0.74t t = 3.706*** 65.3 f 2.43 t = 5.939*** 45,4 5 1.441 t = 0.529 86.3 5 2.01 t = 2.127* 33.4 f 0.94 t = 3.539**

20.3 f 1.15 t = 2.293* 70.9 5 4.48 t = 3.169*** 58.1 f 2.54 t = 3.200** 112.4 f 4.69 t = 1.840 29.1 f 1.19 t = 5.325***

refed for 14 days ( n = 20)

111: Children

refed for at least 2 months (n = 10)

20.7 5 1.27 t = 2.396* 84.1 5 3.99 t = 2.136* 54.5 f 3.67 t = 2.331* 126.6 f 7.81 t = 2.877* 30.8 f 1.31 t = 5.338***

IV: Controls

5

SEM)

t l-I1

t 11-111

t 1-111

( n = 7) 25.0

f

1.10

0.688

0.253

0.972

95.9

f

3.28

1.179

1.897

3.992***

43.9

f

1.73

4.575***

0.820

2.815**

96.5 5 5.44

5.658***

1.649

7.102***

40.4

2.917**

0.924

1.473

f

0.99

Comparisons by Student’s t-test. The t values concern the comparison of the mean observed in the patients with the mean found in the controls. *0.01 < P < 0 . 0 5 ; * * 0 . 0 0 1

A reassessment of intravascular volume measurements in protein--calorie malnutrition.

European Journal of Clinical Investigation (1 977) 7, 161 - 165 A reassessment of intravascular volume measurements in protein-calorie malnutrition P...
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