Fluid calculation in neonates
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This document discusses fluid calculation and homeostasis in neonates. It notes that water and electrolyte balance is vital but different in neonates compared to older children and adults due to rapid developmental changes. It outlines the physiology of total body water, intracellular water, and extracellular water. It also discusses changes that occur at birth and how to assess hydration status in neonates through monitoring things like urine output, weight, physical exam findings and lab tests. Maintaining appropriate fluid and electrolyte balance is important for health in preterm infants.
Fluid calculation in neonates
- 1. FLUID CALCULATION IN NEONATES Mrs. Arifa T N First year M.Sc Nursing, MIMS CON
- 2. Introduction Water and electrolytes are vital components of the body at any age. The laws that regulate fluid and electrolyte balance in the newborn are the same as those that control this process in children and adults the newborn’s body water distribution is both quantitatively and qualitatively different Furthermore, rapid changes occur at the time of birth, and sick newborns pose additional challenges. Consequently, water and electrolyte homeostasis is of vital importance and special care is required to maintain an appropriate balance, especially in very- low-birth-weight (VLBW) infants.
- 3. Water Physiology. Water is the main component of the human body. It is distributed both inside and outside the cells: Therefore a practical simplification is to classify total body water (TBW) as, intracellular water (ICW) and extracellularwater (ECW). ICW is the total amount of water in all the body’s cells. ECW is the total amount of water outside the cells; it comprises the water in the interstitial space and in the intravascular space (plasma).
- 4. In each compartment, a main solute acts to keep water in the compartment: The volume of the intracellular compartment is maintained mainly by potassium salts and is regulated by the Na-K cellular pump. The volume of the extracellular compartment is maintained mainly by sodium salts and is regulated by the kidneys. In the extracellular space, the volume of the intravascular compartment is maintained main
- 5. Changes in Water distribution
- 8. Postnatal Adaptation Fluid management is easier if one remembers a few simpleprinciples: (1) to separate water from sodium requirements; (2) to keep maintenance fluids separate from fluids given to correct electrolyte abnormalities; (3) to recognize the pattern of neonatal diuresis. Monitoring a newborn’s urine output(UOP) can help to individualize fluid requirements
- 10. Appropriate administration of fluid is important, because both excessive fluid restriction and fluid overload lead to clinical consequences. Excessive fluid restriction may lead to dehydration, hyperosmolality, hypoglycemia, and hyperbilirubinemia. In preterm infants, high volumes of parenteral fluids have been associated with a higher incidence of PDA, BPD, and necrotizing enterocolitis.
- 11. It is important to realize that the occurrence of BPD has been correlated with fluid volume administered during the first 4 days of life. Maintaining the fluid and electrolyte balance, therefore, is extremely important in preterm infants. Close monitoring of clinical hydration, body weight, UOP, and the serum sodium concentration should allow the best possible decisions on fluid administration
- 12. Assessment and Evaluation in Fluid and Electrolyte Therapy The estimation of a patient’s fluid and nutritional needs depends on the infant’s age and weight and the disease process involved Fluid needs can be calculated using body weight, body surface area, or caloric expenditure Caloric expenditure is an easy method in which the infant’s caloric needs are calculated, and fluid and electrolyte requirements are related to it.
- 13. To begin these calculations, it must be remembered that 1 kcal is the amount of heat needed to raise 1 L of water 1°C. Caloric expenditures up to 10 kg = 100 cal/kg/24 hr. For example, a 1,700-g infant would expend 170 calories in 24 hours, whereas a 460-g infant would expend 46 calories in 24 hours. This can be expressed as Energy intake= energy stored + Energy expended + Energy excreted
- 14. Caloric expenditures can be modified by an increase or decrease in body temperature and by specific disease states. Caloric expenditure can be used to determine water needs, because for every 100 calories metabolized, 100 mL of fluid is needed Water needs are determined by calculating IWL from the skin and pulmonary system and actual losses from the urine, stool, and sweat
- 16. Fluids usually are calculated on a daily basis, taking into consideration past losses, projected losses, and maintenance requirements. Electrolyte requirements usually are calculated on the basis of 100 calories metabolized: Sodium: 2 to 3 mEq/100 cal/24 hr (2–3 mEq/kg/d) Potassium: 1 to 2 mEq/100 cal/24 hr (1–2 mEq/kg/d) Standard IV solutions containing a predetermined amount of sodium are routinely used in neonatal intensive care units (e.g., 5% dextrose in 0.45% NaCl) with potassium chloride and other electrolytes or minerals added as indicated
- 17. Caloric requirements cannot be met solely by the IV solutions commonly used in NICUs (i.e., 5% or 10% dextrose). These solutions are relatively low in calories, as there are only 4 calories per gram of glucosecarbohydrate). The number of calories in IV solutions is calculated on a percent solution and based on grams per 100 mL. Therefore 5% dextrose in water (D5W) contains 5 g of dextrose per 100 mL of fluid, 10% dextrose in water (D10W) contains 10 g/100 ml, and so on. To carry this calculation further, D5W and D10W IV solutions contain 20 and 40 calories, respectively (D5W = 5 g/100 mL at 4 cal/g = 20 cal).
- 18. An essential test of the infant’s response to IV glucose therapy can easily be done at the bedside with a urine dipstick and a few drops of urine Determination of the specific gravity is another essential bedside test that requires only a few drops of urine. The specific gravity, which normally is between 1.008 and 1.012, is an early indicator of hydration status. Fluid intake and output should be strictly monitored to ensure adequate hydration
- 19. UOP is monitored and calculated hourly over a 24- hour period. It should be no less than 1 mL/kg/hr/d. For example, for a 2-kg infant: UOP = 240 mL/24 hr = 10 mL/2 kg = 5 mL/kg/hr Weight is an important indicator of overall fluid status. Infants are usually weighed daily
- 20. The physical examination can reveal changes in the infant’s fluid status and should be used in conjunction with laboratory data to plan interventions in fluid and electrolyte therapy. Color: Pink and well perfused, rather than pale and mottled (indicates dehydration) Skin turgor: Good turgor, rather than “tenting” (indicates dehydration) or edematous and shiny (indicates fluid overload) Activity: Active with good tone, rather than lethargic and hypotonic (indicates dehydration or overhydration) Mucous membranes: Pink and moist, rather than dry and gray (indicates dehydration)
- 21. Fontanelles: Soft and flat, rather than depressed (indicates dehydration) or tense and full (may indicate overhydration) Vital signs: Heart rate, rhythm, blood pressure and temperature within normal range for gestational age UOP: Normal (e.g., ~1 cc/kg/hr), rather than excessive (indicates overhydration), diminished, or absent (indicating dehydration)
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