Background: The water-deficit equation {WD(1) = 0.6 × B(m) × [1 – (140 ÷ Na(+))]; B(m) denotes body mass} is used in medicine and nutrition to estimate the volume (L) of water required to correct dehydration during the initial stages of fluid-replacement therapy.

Table of Contents

## How do you calculate free water deficit?

Background: The water-deficit equation {WD(1) = 0.6 × B(m) × [1 – (140 ÷ Na(+))]; B(m) denotes body mass} is used in medicine and nutrition to estimate the volume (L) of water required to correct dehydration during the initial stages of fluid-replacement therapy.

**How do you calculate free water in IV fluids?**

Free water deficit (FWD) is calculated using the following equation:

- FWD (L) = 0.6 × weight (kg) × [(Napatient/Nanormal) − 1]
- 0.6 × 20 × [(180/145) − 1] = 2.9 L.
- Napatient − Nanormal = 180 − 145 = 35 mEq/L.
- 35 mEq/L × 0.5 mEq/L/h = 70 hours.

### What is free water deficit Hypernatremia?

Calculates free water deficit by estimated total body water. Pearls/Pitfalls. This tool provides an estimate of free water deficit based on a patient’s body weight; this can be incorrect in patients with signfiicant weight gain or loss (especially from fluid sources).

**How do you calculate volume deficit?**

Deficit (mL) = weight (kg) x % dehydration x 10 In the first 24 hours replace 5% dehydration.

## What is a water deficit?

Definition. Water deficits occur when water demand exceeds supply. The disparity between human activity and water resources has resulted in increasing incidences of local and regional water crises. Collectively, this has been defined as the global water crisis.

**How do you calculate total body water?**

The easy way to calculate total body water is simply to multiply 0.6 times your weight in kilograms, since roughly 2/3 of your body weight is water.

### What is IV free water?

The physician’s concern with giving sodium or dextrose to a patient with CHF and a high blood sugar led to an order to change the patient’s peripheral IV to “free water” at 100 mL/hr. “Free water” refers to water not associated with organic or inorganic ions.

**What is a normal free water deficit?**

Correction of free water deficit 10–12 mEq/L per 24 hours). Oral rehydration with free access to water may be sufficient in stable and alert patients.

## How do you calculate free water flushes for hypernatremia?

Calculation of free water deficit in hypernatremia

- Estimate the patient’s total body water (TBW): TBW (L) = k x weight (kg).
- Calculate FWD (L) = TBW (L) x ((serum Na+ concentration/140)-1).
- Estimate ongoing free water losses (input/output chart, insensible losses).

**How do you calculate sodium deficit?**

The approximate Na+ deficit can be estimated by using the following formula (0.5 L/kg for females): Na+ Deficit (mEq) = (Desired Na+ – Measured Na+) x 0.6 L/kg x Weight (kg)

### How do you calculate volume of dehydration?

This is calculated by dividing the difference between the pre-illness and illness weights by the pre-illness weight, then multiplying by 100 (Table 5). For example, a 10-kg patient who has lost 1 kg is 10% dehydrated. Every 1 kg of weight lost is equivalent to 1 L of fluid loss.

**How is electrolyte deficit calculated?**

## What is water deficit and water surplus?

surplus means that the value of rainfall is greater than the potential evapotranspiration during a given period, while the water deficit means that potential evapotranspiration is greater than the rainfall.

**How do you calculate hydration percentage?**

To get the percentage of water in your body, assume 1 liter equals 1 kilogram and then divide your TBW by your weight. It’s a simplistic estimate, but it will give you an idea if you’re in a healthy range for percentage of water in your body.

### What is TBW in weight loss?

This is the total amount of water in the body expressed as a percentage of total weight. Up to 60% of the human body contains water.

**How much free water is in normal saline?**

Sixty-eight percent (n=34) of dietitians chart the water content in enteral feedings as “free water.” Although normal saline contains no “free water,” only 15% (n=10) of the dietitians surveyed consider normal saline to be 0% FW.

## What is free water fluids?

• Tea • Water • Soda Page 2 Free water describes fluids with minimal to no sodium content. You may be on a “Free water restriction” to correct low sodium levels. These fluids are listed under “Low Sodium Fluids”.

**How is Fwf calculated?**

Variables and formula

- Free water deficit = TBW x (Measured Na / Ideal Na – 1)
- ■ Female FWD = 0.5 x Weight in kg x (Measured Na / Ideal Na – 1)
- ■ Male FWD = 0.6 x Weight in kg x (Measured Na / Ideal Na – 1)

### How do you calculate sodium correction in hypernatremia?

This man is found to have hypernatremia due to insensible water loss. To reduce the man’s serum sodium, D5W will be used. Thus, the retention of 1 L of D5W will reduce his serum sodium by (0 – 165) ÷ (35 + 1) = -4.6 mmol. The goal is to reduce his serum sodium by no more than 10 mmol/L in a 24-hour period.

**How do you calculate free water deficit in hyponatremia?**

V. Calculation: Free Water Deficit (Hypernatremia)

- Free Water Deficit (FWD in L) = (Normal TBW) – (Current TBW)
- Free Water Deficit (FWD in L) = (Normal TBW) * (sNa – 140) / 140.
- Free Water Deficit (FWD in L) = (Normal TBW) * (sNa/140 – 1)
- Adjustments to Total Body Water.

## How to calculate the free water deficit?

– Young men – 0.6% – Young women and elderly men – 0.5% – Elderly women – 0.4%

**How to correct free water deficit?**

– Free water via oral or peg tube if mentating well – D5, 1/4 NS, or 1/2 NS if unable to take by mouth – Only use normal saline if the patient is hypotensive, orthostatic, or with frank hemodynamic compromise.

### How to calculate free water?

Always carrying a water bottle wit you where ever you go

**How to calculate water deficit?**

– Adrogue HJ, Madias NE. Hypernatremia. N Engl J Med. 2000;342 (20):1493-1499. – If you prefer podcast form http://emcrit.org/podcasts/hypernatremia/ – Free water deficit calculator http://www.mdcalc.com/free-water-deficit-hypernatremia/ – Sodium correction in hyper/hyponatremia http://www.mdcalc.com/sodium-correction-rate-hyponatremia-hypernatremia/