This IV maintenance fluids calculator computes fluid requirement for children and infants based on their weight and 2 different formulas for fluid rate. In the text below the form you can discover, amongst other indications, the formulas used and an example calculation.

## How does this IV maintenance fluids calculator work?

This health tool estimates the fluid requirement in the case of pediatric patients based on the formulas beyond the Holliday-Segar nomogram and the 4 – 2 – 1 rule.

The only requirement in the IV maintenance fluids calculator is to input the weight of the pediatric patient in either kg or lbs. Given that the formulas use kg as standard weight unit, lbs will be transformed to kg.

Weight based dosing of fluids has proven to be most accurate as total body water relies on weight.

Please note that the calculator cannot be applied to newborns (0 – 28 zile after full term pregnancy), therefore the minimum weight value to input is 3.5 kg.

In order to calculate the daily volume, the following formulas are applied:

Weight |
Fluid Maintenance By Holliday-Segar Nomogram |

3.5 – 10 kg | 100 mL/kg |

>10 – 20 kg | 100 mL/kg for the first 10 kg, then 50 mL for each kg past 10 kg |

>20 – 65 kg | 1500 mL plus 20 mL for each kg past 20 kg |

>65 kg | 2400 mL |

The fluid rate in mL/hr = Daily volume / 24

The 4 – 2 – 1 rule has the following indications:

Weight |
Fluid Maintenance By 4 – 2 – 1 Rule |

3.5 – 10 kg | 4 mL/hr for each kg |

>10 – 20 kg | 4 mL/hr for each of the first 10 kg, then 2 mL/hr for each kg past 10 kg |

>20 – 65 kg | 60 mL/hr plus 1 mL/hr for each kg past 20 kg |

>65 kg | 105 mL/hr |

This calculator allows determination of maintenance fluids for pediatric patients, however, past, current and prospective hydration statuses need to be taken in consideration and given the consequences of under dosing (dehydration, renal insufficiency) and over dosing (edema, fluid overload) the calculations may need to be adjusted.

At the same time, specific patient pathology, such as renal conditions or burn injury need to be accounted separately.

As a rule of thumb, water loss (and water requirement) is function of caloric expenditure and the total daily water requirement to replace insensible and urinary water loss in hospitalized patients is approximately 100 mL/ 100 kcal/day.

## Example of a IV fluid calculation

These are the two methods for calculating pediatric maintenance fluid rates, applied in the case of a child weighing 26 kg.

1) Daily volume formula: (100 mL for each of the first 10 kg) + (50 mL for each kg between 11 and 20) + (20 mL for each additional kg past 20 kg) = 1,000 mL + 500 mL + 120 mL = 1,620 mL.

Fluid rate = 1,620 / 24 = 68 mL (67.5).

2) 4 – 2 – 1 rule:

First 10 kg with 4 mL/hr, the following 10 kg with 2 mL/hr and the rest of 6 kg with 1 mL/hr = 10 x 4 + 10 x 2 + 6 = 66 mL/hr.

## Maintenance fluid therapy

Fluid therapy is instituted in order to preserve the normal volume of body fluids and their electrolyte composition. The two components are homeostasis preserving maintenance and repletion.

The first replaces the ongoing losses of water and electrolytes due to physiologic processes (respiration, sweat, urine and stool) while the second corrects deficits caused by illnesses and physiologic abnormalities.

Intravascular fluid balance (essential for cardiac output optimization and tissue oxygenation) is influenced by three types of circumstances:

■ Preoperative;

■ Intraoperative;

■ Postoperative.

Usually fluid loss takes place at a normal rate, however, febrile infants and children have a greater transcutaneous evaporative water loss.

Total water loss is broken into three components:

■ Respiratory loss: 20%;

■ Transcutaneous loss: 30%;

■ Urine: 50%.

The most common cause of dehydration in pediatric patients is diarrheal fluid loss. In these cases, depending on the maintained serum sodium level (normal range between 135 – 145 mEq/L), electrolyte loss can vary from isotonic to hypo-osmolar.

## References

1) Meyers RS. (2009) Pediatric Fluid and Electrolyte Therapy. J Pediatr Pharmacol Ther; 14(4): 204–211.

2) Holliday MA, Segar WE. (1957) The maintenance need for water in parenteral fluid therapy. Pediatrics. May; 19(5):823-32.

3) Oh TH. (1980) Formulas for calculating fluid maintenance requirements. Anesthesiology; 53(4):351.

4) Aker J, O'Sullivan C. (1998) The selection and administration of perioperative intravenous fluids for the pediatric patient. J Perianesth Nurs; 13(3):172-81.

24 May, 2016