FLUID CONTENT OF THE REGULAR DIET - Sample (Container Size and Menus May Vary)
Breakfast
Juice (4 oz)	120 ml
Milk (8 oz)	240 ml
Coffee (6 oz)	180 ml
Water (8 oz)	240 ml
Noon
Soup (6 oz)	180 ml
Tea (8 oz)	240 ml
Water (8 oz)	240 ml
Evening
Milk (8 oz)	240 ml
Tea (8 oz)	240 ml
Water (8 oz)	240 ml
TOTAL	2160 ml

Treatment and Prevention of Fluid Deficit
An appropriate assessment is made by the physician to determine if water depletion alone (dehydration) or the more common sodium/water (volume) depletion is present.  Treatment is accomplished by increasing oral intake of fluid and electrolytes as needed.  Patients with more severe cases and those who are unable to take fluids by mouth are treated by appropriate intravenous fluid replacement.  (Note:  Internal sequestering, also known as third spacing, may create a deficit of water in some compartments, although total body water is unaltered.  Replacement water requirements may be greatly increased in peritonitis, pancreatitis, enteritis, ileus, or portal vein thrombosis.)

    An evaluation of fluid requirements should be made on an individual basis.  Urinary specific gravity (Usg) and urinary osmolality (Uosm) are good indicators of hydration or dehydration in young, healthy and active adult males and females (Grade II) (2).  Urine color (Ucol) correlates well with urinary specific gravity and urinary osmolality and can be used as an indicator of hydration status (Grade II) (2). In addition, body mass loss of over 3% is another good indicator of dehydration (Grade II) (2). In some cases, a precise intake and output record may be necessary to determine and meet fluid requirements. There are several methods to determine fluid requirements (2).  Currently, no evidence exists comparing which methods are best to use when estimating fluid needs in adults (Grade V) (2).  Various methods include: 

General guidelines for calculating fluid needs based on age are:
1.	Pediatrics (1-6)
	Weight (kg)a	Fluid Requirement (ml/kg/day)
	First 10 kg	100
	11 – 20 kg	1000 + 50 ml for each kg above 10 kg
	>20 kg	1500 + 20 ml for each kg >20 kg
	aThis method referred to as Holliday-Segar Method, original citation: Holliday MA, Seger WE.  The maintenance need for water in parenteral fluid therapy.  Pediatrics.  1957;19:823-832.
2.	Adults (7-9)
	Weight (kg)	Fluid Requirement (ml/kg/day)
	First 10 kg  of body weight	100
	Second 10 kg of body weight	50
	Each additional kilogram	20 mL/kg(<50 years of age)
		15 mL/kg(>50 years of age)
*In obese patients, actual weight for height is used
Other Suggested Methods (6,7,8)
Children over 20 kg: 1500 ml/day + 20 ml/kg above 20 kg
Active young adults with large muscle mass: 40 ml/kg per day (6)
Adults between 18 - 55 years: 35 ml/kg per day (8)
For persons 55 - 65 years old with no major cardiac or renal diseases: 30 ml/kg actual weight per day (7)
For persons >65 years old: 25 ml/kg
For residents of long-term care facilities, minimum 1500 ml - 2000 ml daily (9,10)
Patients with pressure ulcers: 30 - 35 ml/kg of body weight
Patients with heart failure: 20 - 25 ml/kg of body weight
RDA: 1 ml/kcal (1,7)
3.	Calculating fluid deficit (5)
	Calculated Water Deficit = (% TBW) ´ (BW) ´ [1 - (Na Predicted/Na Measured)] where TBW = total body water
	% TBW, normal adult male = 60
	% TBW, lean adult male = 70
	% TBW, obese adult male = 50
	% TBW, normal adult female = 50
	% TBW, lean adult female = 60
	% TBW, obese adult female = 42
	BW = actual body weight in kilograms
	Na Predicted = constant average serum sodium of 140 mEq/L
	Na Measured = patient’s actual measured serum sodium
4.	One bed change due to perspiration represents approximately 1 L of fluid lost (12).
5.	Patients receiving mechanical ventilation or other source of humidified oxygen can absorb up to an additional 1000 ml of fluid daily, whereas unhumidified oxygen therapy can result in a net loss of fluid (12).
6.	Patients treated on air-fluidized beds set at higher temperatures are at greater risk of dehydration due to an increase in insensible water loss associated with the warmer bed temperatures.  Patients who require air-fluidized beds set at a higher temperature will need additional fluids, estimated to be approximately 10 to 15 mL/kg (13,14).    For beds set at temperatures (86°F), fluid loss is similar to that on a conventional bed (480 ml/m2/24 h).  However, when the bed temperature is high (94°F), fluid loss may increase up to 80% (938 ml/m2/24 h) in a 70-kg person (13).  (Bed temperatures are adjustable and usually set between 88° and 93°F.)
7.	Minimal fluid requirements: 2000 to 3000 ml/day intake is necessary to yield approximately 1000 to 1500 ml/day in urine output.

Assessment of Fluid Status
The clinical assessment of total body water (TBW) is generally inaccurate (Grade II) (2).  A body mass loss of over 3% is a good indicator of dehydration (Grade II) (2).  More than 10% of TBW may be lost before evidence of hypovolemia appears.  The thirst mechanism is activated when the decrease in TBW reaches approximately 2%.  Serial assessment of body weight is probably the most reliable parameter, especially because water makes up such a large proportion of total body weight (2,12).  Along with serial assessment, the following physical alterations can be assessed to help determine hydration status (15,16).

Volume deficit

• Decreased moisture in the oral cavity
• Decreased skin and tongue turgor (elasticity); skin may remain slightly elevated after being pinched
• Flattened neck and peripheral veins in supine position
• Decreased urinary output (<30 ml/h without renal failure)
• Acute weight loss (>1 lb /day)

Volume excess

• Clinical apparent edema is usually not present until 12 - 15 L of fluid has accumulated
• 1 L fluid = 1 kg weight
• Pitting edema, especially in dependent parts of the body (eg, feet, ankles, and sacrum)
• Distended peripheral and neck veins
• Symptoms of heart failure or pulmonary edema
• Central venous pressure >11 cm H20 

    Laboratory values used to evaluate fluid status include urine specific gravity, urine osmolality, serum electrolytes; serum osmolality; hematocrit; blood, urea nitrogen (BUN); and urine specific gravity.  Serum sodium is the best indicator of intracellular fluid disorders.  The hematocrit reflects the proportion of blood plasma to red blood cells.  Fluid loss causes hemoconcentration and serum osmolality; fluid gain causes hemodilution and decreases serum osmolality.  A rise in BUN level frequently reflects a fluid deficit state and a fluid deficit causes urine to be concentrated (specific gravity >1.030); a fluid excess dilutes urine (specific gravity <1.010) (12). 

    Aging increases the risk for dehydration based on the physical and psychological changes.  The elderly often lack the ability to recognize thirst, have aged kidneys that may have a decreased ability to concentrate urine, fear urinary incontinence and thus do not drink sufficient fluids, have acute or chronic illnesses that alter fluid and electrolyte balance (17), and have a decrease in total body water from 60% to 45%.

See: Enteral Nutrition, for discussion of calculation of free water in tube feeding.

Fluid Restriction
In heart failure, ascites, end-stage renal disease, and other disorders, patients retain fluid.  A fluid restriction is often useful in the management of these conditions.

See: HEART FAILURE MANAGEMENT OF ADULT RENAL FAILURE: ACUTE RENAL FAILURE AND CHRONIC KIDNEY DISEASE

References

1. Institute of Medicine.  Dietary Reference Intakes:  Water, Potassium, Sodium, Chloride, and Sulfate.  Washington, D. C: National Academy Press; 2004.   
2. Hydration Evidence-Analysis Project. American Dietetic Association Evidence Analysis Library.  American Dietetic Association; 2007.   Available at: http://www.adaevidencelibrary.com.  Accessed November 9, 2007.
3. Kleiner SM, Water an essential but overlooked nutrient. J Am Diet Assoc. 1999;99:200-205.
4. Hendricks KM, Walker WA. Manual of Pediatric Nutrition. 2nd ed. Philadelphia: Pa: BC Becker Inc;1990.
5. Blackburn G, Bell SJ, Mullen JL. Appendix B: Macronutrient requirements. In:  Blackburn GL, Bell SJ, Mullen JL, eds. Nutritional Medicine: A Case Management Approach. Philadelphia, Pa: W. B. Saunders Co; 1989.
6. Pediatric Manual of Clinical Dietetics.  2nd ed. Chicago: Il: The American Dietetic Association; 2003.
7. Food and Nutrition Board, National Academy of Sciences.  Recommended Dietary Allowances.  10th ed.  Washington, DC: National Academy Press; 1989.
8. Chidester JC, Spangler AA. Fluid intake in the institutionalized elderly. J Am Diet Assoc. 1997;97:23-28.
9.  Dietitians in nutrition support: fluid requirements.  Support Line. 1991;13:18.
10. Chernoff R. Meeting the nutritional needs of the elderly in the institutionalized setting. Nutr Rev. 1994;52:132-136.
11. Holben DH, Hassell JT, Williams JL, Helle B. Fluid intake compared with established standards and symptoms of dehydration among elderly residents of a long-term care facility. J Am Diet Assoc. 1999;99:1447-1449.
12. Dolan JT. Fluid and Electrolyte Physiology and pathophysiology. In: Dolan JT, ed. Critical Care Nursing. Philadelphia, Pa: FA Davis Co.; 1991:434.
13. Ayello EA, Thomas Dr, Litchford MA.  Nutrition aspects of wound healing.  Home Healthc Nurse.  1999;17:719-729.
14. Breslow RA. Nutrition and air-fluidized beds: a literature review. Adv Wound Care. 1994;3:57-60.
15. Methany NM. Fundamental concepts and definitions. In: Methany NM, ed. Fluid and Electrolyte Balance: Nursing Considerations. Philadelphia, Pa: JB Lippincott; 1989:29-34.
16. Lysen L. Quick Reference to Clinical Dietetics. Gaithersburg, Md: Aspen Publishers; 1997.
17. Position of The American Dietetic Association: nutrition, aging, and the continuum of care. J Am Diet Assoc. 2000;100:580-595.