A Maintenance Fluids Calculator (or MIVF calculator) is a clinical tool utilized in healthcare settings to determine the appropriate amount of fluid required by a patient to sustain normal bodily functions and hydration levels during periods of rest or minimal activity. This calculator employs established medical formulas such as the Holliday-Segar method or the "4-2-1" rule, which are grounded in empirical data and medical research.

The primary objective of a Maintenance Fluids calculator is to ensure that patients receive sufficient hydration to support physiological processes such as circulation, kidney function, and electrolyte balance.

## The Holliday-Segar method

The Holliday-Segar method, also known as the Holliday-Segar formula, is a widely recognized and validated formula utilized in medical practice to calculate maintenance fluid requirements for patients. This method was first described by M.A. Holliday and W.P. Segar in their seminal publication titled "The Maintenance Need for Water in Parenteral Fluid Therapy" published in Pediatrics in 1957 (Holliday & Segar, 1957).

The Holliday-Segar formula is based on the principle that fluid requirements are proportional to body weight.

The Holliday-Segar method is commonly expressed as follows:

- For the first 10 kilograms of body weight: 100 milliliters of fluid per kilogram per day.
- For the next 10 kilograms of body weight (11 to 20 kilograms): An additional 50 milliliters of fluid per kilogram per day.
- For every additional kilogram beyond 20 kilograms: An extra 20 milliliters of fluid per kilogram per day.

### Example of maintenance fluids calculation using the Holliday-Segar method

Let's walk through an example calculation using the Holliday-Segar method. Suppose we have a child who weighs 18 kilograms.

According to the Holliday-Segar method:

- For the first 10 kilograms of body weight: 100 milliliters of fluid per kilogram per day.
- For the next 10 kilograms of body weight (11 to 20 kilograms): An additional 50 milliliters of fluid per kilogram per day.

So, for the first 10 kilograms: 10 kg * 100 mL/kg/day = 1000 mL/day

And for the next 8 kilograms (since the patient's weight is 18 kg): 8 kg * 50 mL/kg/day = 400 mL/day

Now, add these two amounts together: 1000 mL/day + 400 mL/day = 1400 mL/day

Therefore, according to the Holliday-Segar method, the estimated maintenance fluid requirement for this pediatric patient weighing 18 kilograms would be 1400 milliliters per day - check with the calculator .

## 4-2-1 rule

The 4-2-1 rule is a simplified method for estimating hourly maintenance fluid requirements in pediatric patients.

The 4-2-1 rule provides an alternative approach to the Holliday-Segar formula, which calculates daily fluid requirements.

Instead, it estimates the hourly fluid rate based on the patient's weight.

The rule is as follows:

Hourly fluid requirement = 4 mL/kg/hour for the first 10 kg of body weight + 2 mL/kg/hour for the next 10 kg of body weight + 1 mL/kg/hour for each additional kg above 20 kg

### 4-2-1 calculation example

For example, for a child weighing 15 kg, the hourly fluid requirement would be calculated as:

Hourly fluid requirement = (4 mL/kg/hour × 10 kg) + (2 mL/kg/hour × 5 kg) = 40 mL/hour + 10 mL/hour = 50 mL/hour - check

The 4-2-1 rule is a convenient and easy-to-remember method for estimating maintenance fluid rates in pediatric patients.

However, it is important to note that this rule is a simplified approach and may not account for individual variations in fluid requirements due to factors such as age, clinical condition, and ongoing fluid losses.

While the 4-2-1 rule can be useful in clinical practice, it should be used judiciously and in conjunction with careful monitoring of the patient's hydration status, electrolyte levels, and overall clinical condition. Adjustments to the fluid rate may be necessary based on the individual patient's response and ongoing assessment.

## Holliday-Segars method and 4-2-1 rule table

Weight (kg) | Holliday-Segars method (daily) | 4-2-1 rule (hourly) |
---|---|---|

First 10 kg (3-10 kg) | 100 ml/kg/24h | 4 ml/kg/h |

Next 10 kg (11-20 kg) | 50 ml/kg/24h | 2 ml/kg/h |

Above 20 kg | 20 ml/kg/24h | 1 ml/kg/h |

## Fluid bolus

A fluid bolus is a medical intervention involving the rapid administration of a relatively large volume of intravenous (IV) fluid over a short period of time. The purpose of a fluid bolus is to quickly increase circulating blood volume and improve tissue perfusion, especially in cases of acute dehydration, hypovolemia (low blood volume), or shock.

Calculating a fluid bolus involves determining the volume of fluid to administer rapidly over a short period to address conditions such as dehydration, hypovolemia, or shock.

The volume of the fluid bolus depends on various factors, including the patient's weight, severity of fluid deficit, and clinical condition.

A common starting point for fluid boluses is **20 milliliters per kilogram (mL/kg) of body weight**.

For example, if the patient weighs 12 kilograms and you decide to administer a bolus of 20 mL/kg, the calculation would be:

Bolus volume = 20 mL/kg * 12 kg = 240 mL - calculate

Based on research by

- Malcolm A. Holliday; William E. Segar THE MAINTENANCE NEED FOR WATER IN PARENTERAL FLUID THERAPY Pediatrics (1957) 19 (5): 823–832.
- Meyers RS. Pediatric fluid and electrolyte therapy. J Pediatr Pharmacol Ther. 2009 Oct;14(4):204-11.