The management of dehydrated children depends on the degree of fluid loss, as well as a patient's ability to tolerate oral liquids. Mildly dehydrated patients (<5 percent) who tolerate Pedialyte can usually be discharged home on clear liquids, with close follow-up. Moderately dehydrated patients generally require intravenous therapy, although oral rehydration (discussed below) is an option.
Severely dehydrated patients require aggressive resuscitation. Boluses of 20 mL/kg of 0.9 normal saline (NS) are given until improved mental status, vital signs, and peripheral perfusion indicate stable intravascular volume.4 In extreme situations, an intraosseous line may be necessary. Fluid replacement then consists of replacing 50 percent of the estimated volume deficit in the first 8 h, and the remainder of the deficit in the next 16 h. If diarrhea continues, the ongoing losses must also be replaced. Maintenance fluids are added to the deficit replacement.5
For example, a 12-kg infant is estimated to be 10 percent dehydrated. After a 20 mL/kg bolus of 0.9 NS, she is alert and perfusion is adequate. Fluid orders can then consist of
1. Maintenance is 100 mL/kg x 10 kg/24 h = 1000 mL + (50 mL/kg x 2 kg/24 h) = 100 mL, for a total of 1100 mL/24 h or 46 mL/h.
2. Deficit = 10 percent of body weight (1.2 kg) = 1200 mL; replace 600 mL over the first 8 h or 75 mL/h; replace 600 mL over the next 16 h or 38 mL/h.
Thus, for the first 8 h, maintenance + deficit = 121 mL/h; for the next 16 h, maintenance + deficit = 84 mL/h.
Appropriate rehydrating solutions in infants are 5% D/0.2NS or 5% D/0.45NS. In infants, 5% D in 0.2NS is isotonic for maintainance rehydration in isotonic dehydration. In children, 5% D/0.45NS can be used for maintainance rehydration in isotonic dehydration. Glucose is added to the solution to minimize further catabolism. Remember that 0.9NS is used for bolus rehydration. After the patient has urinated, potassium can be added at a maximum concentration of 40 meq/L. Most patients will begin to tolerate oral feeding with clear liquids within 24 h. All severely dehydrated patients are admitted to the hospital.
Patients who are moderately dehydrated can be managed in a number of ways. Oral rehydration is an effective modality, but is labor intensive and time-consuming. Some patients can be aggressively rehydrated with normal saline over a period of 2 to 4 h in the emergency department and safely discharged. 46 The success of rapid rehydration may be correlated with an initial serum bicarbonate level of greater than 13 meq/L, but further study is needed to clarify this. Extreme caution should be exercised in using rapid rehydration in neonates and young infants, since the underlying gastroenteritis is likely to continue and these patients are at relatively great risk of cardiovascular compromise. If they are discharged, follow-up must be expedient and absolutely certain. Patients with persistent profuse diarrhea and those with intractable vomiting are candidates for admission. Fluid management is then the same as for severely dehydrated patients, with 50 percent of the deficit replaced in the first 8 h and the remaining 50 percent replaced over the next 16 h.
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