Calculate the GIR 0.750 kg baby with 4.3ml/hr rate of 0.45% DNS 30 ml + 20 ml distal water. Total fluid of 50 ml
Here's the GIR calculation for this baby:
Given Information
- Weight: 0.750 kg
- Infusion rate: 4.3 ml/hr
- Fluid composition: 0.45% DNS 30 ml + 20 ml distilled water (total 50 ml)
Step 1: Find the Dextrose Concentration in the Mixed Fluid
0.45% DNS means 4.5% Dextrose in the stock solution (DNS = Dextrose Normal Saline; 0.45% DNS = Dextrose 4.5% + NaCl 0.45%).
Wait - let me clarify the notation: 0.45% DNS typically refers to Dextrose 5% + 0.45% NaCl in some conventions, but in neonatal practice, "DNS" often means the dextrose concentration is listed first. The most common interpretation of "0.45% DNS" = Dextrose 4.5% (i.e., 4.5 g/100 ml).
Stock solution: 30 ml of 4.5% Dextrose diluted into 50 ml total.
Effective dextrose concentration =
$$\text{Dextrose%} = \frac{4.5 \times 30}{50} = \frac{135}{50} = \mathbf{2.7%}$$
So the final bag has 2.7 g dextrose per 100 ml = 0.027 g/ml.
Step 2: Calculate Dextrose Delivered per Minute
$$\text{Rate} = 4.3 \text{ ml/hr} = \frac{4.3}{60} \text{ ml/min} = 0.07167 \text{ ml/min}$$
$$\text{Dextrose delivered} = 0.07167 \times 0.027 \text{ g/ml} = 0.001935 \text{ g/min}$$
Convert to mg/min:
$$0.001935 \text{ g/min} = 1.935 \text{ mg/min}$$
Step 3: Calculate GIR
$$\text{GIR} = \frac{\text{mg of dextrose per min}}{\text{weight in kg}}$$
$$\text{GIR} = \frac{1.935}{0.750} = \mathbf{2.58 \ mg/kg/min}$$
Summary
| Parameter | Value |
|---|---|
| Effective dextrose % | 2.7% |
| Infusion rate | 4.3 ml/hr |
| Weight | 0.750 kg |
| GIR | ≈ 2.6 mg/kg/min |
Clinical note: A GIR of ~2.6 mg/kg/min is below the normal neonatal requirement of 4-6 mg/kg/min (minimum to suppress catabolism) and well below the target of 6-8 mg/kg/min for most neonates. For a 750g premature baby, consider increasing the dextrose concentration or rate to meet metabolic needs, guided by blood glucose monitoring.
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