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# Mometrix ## Hypovolemia, Dehydration, and Hypervolemia - Dry mucous membranes - 3-10% decrease in body weight Hypovolemia occurs when the loss of extracellular fluid is greater than the intake of fluid. With hypovolemia, fluid and electrolytes are lost in equal proportions so that serum electrol...

# Mometrix ## Hypovolemia, Dehydration, and Hypervolemia - Dry mucous membranes - 3-10% decrease in body weight Hypovolemia occurs when the loss of extracellular fluid is greater than the intake of fluid. With hypovolemia, fluid and electrolytes are lost in equal proportions so that serum electrolyte levels usually remain within normal range unless there are other complications. Hypovolemia can occur as the result of gastrointestinal disorders with diarrhea and/or vomiting, suctioning, and decreased intake. It may also result from fluid shifts that occur with burns and ascites. **Dehydration is loss of fluid alone, causing increased concentrations of electrolytes, such as sodium. Dehydration often relates to hyperthermia, inadequate intake of fluids, or severe diarrhea.** Hypervolemia is retention of extracellular fluid and sodium in normal proportions, so edema is pronounced, but serum sodium levels are usually normal. Hypervolemia may be caused by fluid overload, impairment of fluid balance regulation, heart failure, or cirrhosis of the liver. ## Maintenance Fluid Deficit, Fluid Requirements, and Fluid Replacement Pediatric fluid deficit must also be carefully estimated and managed. Fluid deficit should be replaced over 3 hours with half the first hour and a quarter in the remaining 2 hours. Fluid deficit is calculated by first finding the maintenance fluid requirement: *Maintenance fluid mL X hours NPO = fluid deficit.* Preoperative deficits usually are treated with lactated Ringer's or 1/3 normal saline (which may cause hyperchloremic acidosis). Glucose containing fluids may contribute to hyperglycemia. For weight 10 kg and hourly requirement is 40 mL and 2 mL/kg for each kg >10 kg. For weight >20 kg, the 24-hour fluid requirement is 1500 mL and 20 mL/kg for each kg >20 kg and the hourly requirement is 60 mL and 1 mL/kg for each kg above 20 kg. ### Fluid replacement must account for both blood loss and third-space loss: - **Blood:** Replacement may be with lactated Ringers (3 mL to 1 mL blood loss) or 5% albumin colloid (1 mL to 1 mL blood loss) to maintain hematocrit at predetermined adequate minimal level: - Infants and neonates: >30% (may be as high as 40-50%) - Older children: 20-26% ## Appendicitis Appendicitis is inflammation of the appendix caused by luminal obstruction and pressure within the lumen as secretions build up and can eventually perforate the appendix. Appendicitis can occur in all ages, but infants