Maintenance and Replacement Therapy

Maintenance intravenous fluids are used in a child who cannot be fed enterally. Along with maintenance fluids, children may require concurrent replacement fluids(ongoing loss) if they have continued excessive losses, such as may occur with drainage from a nasogastric (NG) tube or with high urine output because of nephrogenic diabetes insipidus. If dehydration is present, the patient also needs to receive deficit replacement.

MAINTENANCE THERAPY Goals of Maintenance Fluids: 1- Prevent dehydration 2- Prevent electrolyte disorders 3- Prevent ketoacidosis 4- Prevent protein degradation

Body Weight Method for Calculating Daily Maintenance Fluid Volume BODY WEIGHT FLUID PER DAY 0-10 kg 100 mL/kg 11-20 kg 1,000 mL + 50 mL/kg for each kg >10 kg >20 kg 1,500 mL + 20 mL/kg for each kg >20 kg Example 7 kg--------- 700 ml 13 kg-------1150 ml 23 kg-------1560 ml

SELECTION OF MAINTENANCE FLUIDS D5 1/2NS + 20 mEq/L KCl is recommended in the child who is NPO and does not have volume depletion or risk factors for non-osmotic ADH production. Children with volume depletion, baseline hyponatremia, or at risk for non-osmotic ADH production (lung infections such as bronchiolitis or pneumonia; central nervous system infection) should receive D5 NS + 20 mEq/L KCl.

Children with renal insufficiency may be hyperkalemic or unable to excrete potassium and may not tolerate 10 or 20 mEq/L of potassium. Patients with persistent ADH production because of an underlying disease process (syndrome of inappropriate ADH secretion, congestive heart failure, nephrotic syndrome, liver disease) should receive less than maintenance fluids( 1/2 to 2/3). Children with meningitis are fluid restricted unless intravascular volume depletion is present . Fever increases evaporative losses from the skin. These losses are somewhat predictable, leading to a 10-15% increase in maintenance water needs for each 1°C (1.8°F) increase in temperature above 38°C

Adjusting Fluid Therapy for Altered Renal Output OLIGURIA/ANURIA Replacement of insensible fluid losses (25-40% of maintenance) with D5 1/2NS Replace urine output mL/mL with D5 1/2NS ± KCl

Neonatal period Fluid intake in term infants is usually begun at 60-70 mL/kg on day 1 and increased to 100-120 mL/kg by days 2-3. Smaller, more premature infants may need to start with 70-80 mL/kg on day 1 and advance gradually to 150 mL/kg/day Type of fluid: dextrose 10% in the first 24-48 hours then (0.18% NS with D5 ----D5 1/5 NS)

REPLACEMENT FLUIDS(ONGOING LOSS) APPROACH TO REPLACEMENT OF ONGOING LOSSES 1- Replacement Fluid for Diarrhea Solution: D5 1/2NS + 30 mEq/L sodium bicarbonate + 20 mEq/L KCl Replace stool mL/mL every 1-6 hr 2- Replacement Fluid for Emesis or Nasogastric Losses Solution: normal saline + 10 mEq/L KCl Replace output mL/mL every 1- 6 hr

Deficit Therapy Dehydration, most often caused by gastroenteritis, is a common problem in children. Most cases can be managed with oral rehydration Even children with mild to moderate hyponatremic or hypernatremic dehydration can be managed with oral rehydration solution(ORS).

The first step in caring for the child with dehydration is to assess the degree of dehydration Mild dehydration (<5% in an infant; <3% in an older child or adult Moderate dehydration (5-10% in an infant; 3-6% in an older child or adult Severe dehydration (>10% in an infant; >6% in an older child or adult)

The first step in caring for the child with dehydration is to assess the degree of dehydration

CALCULATION OF THE FLUID DEFICIT Determining the fluid deficit necessitates clinical determination of the percentage of dehydration and multiplication of this percentage by the patient’s weight; a child who weighs 10 kg and is 10% dehydrated has a fluid deficit of 1 L. NOTE: 10% mean 100 ml/kg so if the weight is 10 10 x 100= 1000ml ( 1liter)

APPROACH TO SEVERE DEHYDRATION This resuscitation phase requires rapid restoration of the circulating intravascular volume and treatment of shock with an isotonic solution, such as normal saline (NS) or Ringer lactate (LR) The child is given a fluid bolus, usually 20 mL/kg of the isotonic fluid, over approximately 20 min. The child with severe dehydration may require multiple fluid boluses and may need to receive the boluses as fast as possible.

The initial resuscitation and rehydration phase is complete when the child has an adequate intravascular volume. Typically, the child shows clinical improvement, including a lower heart rate, normalization of blood pressure, improved perfusion, better urine output, and a more alert affect.

PLAN SUMMARY

In isonatremic or hyponatremic dehydration, the entire fluid deficit is corrected over 24 hr; a slower approach is used for hypernatremic dehydration Potassium is not usually included in the intravenous fluids until the patient voids and normal renal function is documented via measurement of BUN and creatinine

Monitoring Therapy Vital signs: Pulse Blood pressure Intake and output: Fluid balance Urine output Physical examination: Weight Clinical signs of depletion or overload Electrolytes

Oral Rehydration Therapy Dehydration must be evaluated rapidly and corrected in 4-6 hr according to the degree of dehydration and estimated daily requirements. Limitations to oral rehydration therapy include shock, an ileus, intussusception, carbohydrate intolerance (rare), severe emesis, and high stool output (>10 mL/kg/hr) require initial intravenous rehydration, but oral rehydration is the preferred mode of rehydration and Replacement of ongoing losses.

Risks associated with severe dehydration that might necessitate intravenous resuscitation include: age <6 mo; prematurity; chronic illness; fever >38°C if younger than 3 mo or >39°C if 3-36 mo of age; bloody diarrhea; persistent emesis; poor urine output; and a depressed level of consciousness.

The low-osmolality World Health Organization (WHO) oral rehydration solution (ORS) containing 75 mEq of sodium, 64 mEq of chloride, 20 mEq of potassium, and 75 mmol of glucose per liter, with total osmolarity of 245 mOsm/L, is now the global standard of care and more effective than home fluids, including decarbonated soda beverages, fruit juices, and tea. These are not suitable for rehydration or maintenance therapy because they have inappropriately high osmolalities and low sodium concentrations.

Oral rehydration should be given to infants and children slowly, especially if they have emesis. It can be given initially by a dropper, teaspoon, or syringe, beginning with as little as 5 mL at a time. The volume is increased as tolerated