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Various Equations to Estimate Fluid Requirements in the Adult (19 Years and Older)



No evidence meeting the inclusion-exclusion criteria was found for this question (see Search Plan & Results). However, relevant historical information is presented in the following section on background.

Historical Background

Two historically important narrative review articles, one of negative and one of neutral quality, evaluated the literature that was available at the time that was relevant to methods and/or equations for estimating fluid requirements of humans and mammals.

The first study, an extensive narrative review of negative quality, published in 1933, may be the original reference for the fluid recommendation of 1 milliliter of water per calorie consumed. This recommendation is included in the 10th edition of the Recommended Daily Allowances and is frequently used in clinical practice. Note that this “recommendation” is not based on the findings of a primary research. Rather, it was derived from a composite table titled, Coefficients for Calculating the Water Requirement of an Individual, which the author developed with information extracted from a variety of human and animal studies. In the review article, the author presents his opinion regarding a liberal fluid requirement for an average man. He concluded that the average man required "something like 3400 cc. of water per square meter per 24 hours, making allowance for three times the basal consumption of energy. A typical 3000 Calorie diet as consumed at the table contains perhaps 2000 cc. of preformed plus potential water. Hence 1400 cc. remains to be drunk as such. Roughly, a convenient liberal standard of total water intake for any mammal is 1 cc. per Calorie." (Adolph, 1933).

The second study, a narrative review of neutral quality, examined selected literature related to methods for estimating energy expenditure, insensible water loss, and urinary water loss in hospitalized patients. The authors used this information to derive equations for estimating total energy expenditure and fluid requirements that could be easily remembered in a clinical setting. The equations for estimating total energy expenditure, based on body weight, are: “For weights ranging from 0 to 10 kg, the caloric expenditure is 100 cal per kg per day; from 10 to 20 kg the caloric expenditure is 1000 cal plus 50 cal per kg for each kilogram of body weight more than 10; over 20 kg the caloric expenditure is 1500 cal plus 20 cal/kg for each kilogram more than 20.” The estimated energy requirement was then used to estimate maintenance water needs via the following equation: 100 milliliters of fluid per 100 calories consumed per day (Holliday and Segar, 1957).

In summary, as mentioned above these papers did not meet the criteria for inclusion in this evidence analysis project; however they are presented here for their historic relevance. Adolph (1933) appears to be the original reference for the hydration recommendation of 1 milliliter of water per calorie consumed per day, which has been used in research studies and clinical settings for 70+ years. No papers were identified that validate this recommendation, although Holiday and Segar (1957) presents the same recommendation 20 years later -- 100 milliliters of fluid per 100 calories per day. In coming to the same conclusion, the authors used data taken from different sets of published primary studies and reviews.

Narrative Review

Adolph EF (1933) (negative quality) is an extensive narrative review of the published literature intended to define issues related to the metabolism and distribution of water in body and tissues of mammals. In one section of the paper, the author presents a table with components extracted from various papers, including human and animal studies. The brief "average man" example and author’s considered opinion following the table may be the original reference for the commonly used fluid recommendation of 1 cc of water per calorie consumed. The following are excerpts from the paper:

Introduction, page 336 – “The present review of experimental results emphasizes the data upon normal-man. Where these are not available, data from pathological man and from some mammals are referred to. It must be kept in mind that differences among species and individuals in the quantitative relationships of water are great, enough to discourage broad generalizations based upon observations from diverse sources.”

Table 2 and discussion from pg. 345 of the paper.

Coefficients for Calculating the Water Requirement of an Individual

A = surface area of the body (A) measured in square meters.

E = the energy requirement (E) in large Calories.

Values are in cubic centimeters (cc) per 24 hours. 1 cubic centimeter = 1 milliliter of volume

Fluid Utilized for

Minimum Amount

(cc)

Average to Liberal Amount

(cc)

Growth (or storage)

0

15 A to 30 A

Urinary

400 A

1000 A to 1500 A

Fecal

30 A

90 A to 150 A

Basal extrarenal

250 A

390 A or 1.73 X 0.25 E basal

Exercise (sweat)

1.73 x 0.4 E excess

I.73 x 0.55 E excess

Temperature control (sweat)

0

1800 A (atmospheric “C-32°C.)

24-HOUR TOTAL (approximate)

2100 cc.

3400 to 5000 cc.

“An average man requires, therefore, something like 3400 cc. of water per square meter per 24 hours, making allowance for three times the basal consumption of energy. A typical 3000 Calorie diet as consumed at the table contains perhaps 2000 cc. of preformed plus potential water. Hence 1400 cc. remains to be drunk as such. Roughly, a convenient liberal standard of total water intake for any mammal is 1 cc. per Calorie.”

Holliday MA and Segar WE (1957) (neutral quality) is a narrative review of selected literature related to methods for estimating energy expenditure, insensible water loss, and urinary water loss. The authors used this information to develop formulas for estimating total energy expenditure and fluid requirements that could be easily remembered in a clinical setting. The formula for estimating total energy expenditure (for hospitalized patients) based on body weight alone was: “For weights ranging from 0 to 10 kg, the caloric expenditure is 100 cal/kg/day; from 10 to 20 kg the caloric expenditure is 1000 cal plus 50 cal per kg for each kilogram of body weight more than 10; over 20 kg the caloric expenditure is 1500 cal plus 20 cal per kg for each kilogram more than 20.” The estimated total energy expenditure was then used to estimate maintenance fluid requirements with the following equation: 100 milliliters of fluid per 100 calories expended per day (100ml/100 cal per day). Maintenance requirements for water depend upon insensible loss of water and renal loss. An allowance of 50ml per 100 cal per day will replace insensible loss of water, and 66.7ml per 100 cal per day will replace the average renal loss so that the total requirement is 116.7ml/ per 100 cal per day. As water of oxidation will supply approximately 16.7ml per 100 cal per day, the remaining 100ml per 100 cal per day must be supplied to meet the remaining water losses of patients on parenteral fluid therapy.”




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