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Indian Pediatr 2015;52: 349 -350 |
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Reduced Volume Isotonic Saline as Maintenance
Fluids in Children: Author’s reply
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*Ahmar Shamim and Kamran Afzal
Department of Pediatrics, Jawaharlal Nehru Medical
College, AMU, Aligarh, Uttar Pradesh, India.
Email: * [email protected]
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We thank the author for his interest and comments on our paper [1]. He
has raised some very valid points. We had highlighted in our article
that the risk of hyponatremia with use of hypotonic fluids was almost
twice that with use of isotonic fluid (RR 0.48, 95% CI 0.27, 0.83; P=
0.01). The risk difference and the number-needed-to-harm (NNH) have been
summarized in Table I [1]. As rightly pointed out, the NNH
for hyponatremia was higher (1 in 4) compared to study by Montana, et
al. [2] (1 in 7), possibly because their trial used same volume
fluids in both groups. Similarly from the data of Kanan, et al.
[3], figures for NNH would be 1 in 7 with isotonic fluid in standard
volume and 1 in 9 when reduced volume hypotonic fluid is used. Higher
figures of NNH in our study underline the additional benefit of reducing
the volume of maintenance fluids apart from using isotonic solutions.
Kanan, et al. [3] also showed that use of isotonic saline in
‘standard volume’ reduced the risk of hyponatremia by 12.6% compared to
hypotonic fluid, whereas reducing the volume of hypotonic fluids also
resulted in a risk difference of 10.5%. Our study demonstrated the
cumulative effect of using isotonic fluid in reduced volume but there
was no comparative ‘standard volume’ isotonic fluids group to
demonstrate the benefit of either strategy.
TABLE I Risk of Hyponatremia with Hypotonic vs Isotonic Maintenance Fluid
Time |
Fluid type* |
Hyponatremia (%) |
Risk difference (95% CI) |
NNH(95% CI) |
P value |
At 24 h |
IF |
7 (23.3%) |
30% (6.6% - 53.4%) |
4 (1.9-15.2) |
0.03 |
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HF |
16 (53.3%) |
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At 48 h |
IF |
4 (13.3%) |
30% (8.5% - 51.5%) |
4 (1.9-11.8) |
0.02 |
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HF |
13 (43.3%) |
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Overall |
IF |
10 (33.3%) |
36.7% (13.1% - 60.2%) |
3 (1.7-7.6) |
0.01 |
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HF |
21 (70%) |
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*IF, Isotonic fluid; HF, Hypotonic fluid; N =30 for each
fluid type; NNH: number-needed-to-harm. |
We agree that same amount of potassium was not used
in both arms of this study. If the same amount of potassium were to be
used in both groups, the concentration of potassium would have been 60%
higher in the isotonic fluids group (33.3 meq/L as against 20 meq/L).
Moreover, this would have also increased the tonicity of the fluid by
approximately 7.5%. For maintaining infusion concentration at 20 meq/L,
potassium supplementation needed to be reduced.
We agree that urine osmolality should also have been
measured to estimate free water clearance and could have explained
hyponatremia despite using isotonic fluids.
References
1. Shamim A, Afzal K, Manzir AS. Safety and efficacy
of isotonic (0.9%) vs. hypotonic (0.18%) saline as maintenance
intravenous fluids in children: A randomized controlled trial. Indian
Pediatr. 2014;51:969-74.
2. Montanana PA, Modesto AV, Ocon AP, Lopez PO, Lopez
PJL, Toledo PJD. The use of isotonic fluid as maintenance therapy
prevents iatrogenic hyponatremia in pediatrics: a randomized, controlled
open study. Pediatr Crit Care Med. 2008;9: 589-97.
3. Kannan L, Lodha R, Vivekanandhan S, Bagga A, Kabra
SK, Kabra M. Intravenous fluid regimen and hyponatraemia among children:
A randomized controlled trial. Pediatr Nephrol. 2010;25:2303-9.
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